JP2011022394A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a developer from flowing back due to a shape of inside of a device, and to prevent a conveyance speed of the developer from being reduced. <P>SOLUTION: A developing frame 18 includes, in its inside: a toner storing chamber 18a; a first opening 44 provided above the toner storing chamber 18a; a conveying member 22 to the toner storing chamber, the conveying member being provided inside the toner storing chamber 18a and supplying the developer from the toner storing chamber 18a to the first opening 44; a buffer chamber 18c connected to the toner storing chamber 18a through the first opening 44; a second opening 45 provided in a position different from that of the first opening 44 of the buffer chamber 18c; and a developing chamber 18b connected to the buffer chamber 18c through the second opening 45. The lower end 44a of the first opening 44 is positioned higher than a conveyance support shaft 22b of the conveying member 22 and the upper end 45a of the second opening 45. The lower end 45b of the second opening 45 abuts on the developing chamber bottom surface 26c of the developing chamber 18b. The angle formed between a line, drawn through the lower end 45b and the developing chamber bottom surface 26c, and a horizontal line (a) is set larger than a repose angle of a single component developer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device used in an electrophotographic image forming apparatus and an image forming apparatus including the developing device.

  Conventionally, an electrophotographic image forming apparatus is known. In such an image forming apparatus, after the primary charging device uniformly charges the surface of the image carrier, the exposure device irradiates the image carrier with light and writes an electrostatic image on the surface of the image carrier. Then, the toner is developed from the developer carrier provided inside the developing device to the image carrier. The developed toner is transferred to a sheet by a transfer device, and the sheet is separated from the image carrier. Heat and pressure are applied to the sheet on which the toner has been transferred by a fixing device, and the toner is fixed to the sheet.

  Some of the above-described developing devices have a plurality of toner chambers for stirring the toner, and the toner is moved from the developer carrier to the image carrier after being sufficiently stirred in each toner chamber. Has been. The invention described in Patent Document 1 is disclosed as an invention relating to such a developing device.

  A developing device described in Patent Document 1 includes a developing unit that develops a one-component toner on an electrostatic image on the surface of an image carrier, and a toner cartridge that is connected to the developing unit and conveys the toner to the developing unit. . A control valve is provided between the toner cartridge and the developing unit. Further, this control valve is controlled to open and close by a transport paddle inside the developing unit. In addition, a rotary stirring member is disposed below the control valve.

  According to such a configuration, it is possible to make it difficult for the toner to return from the developing unit to the toner cartridge based on the function of the control valve. Also, based on the function of the rotating stirring member, the deteriorated toner inside the developing unit and the new toner received from the toner cartridge are sufficiently stirred and mixed to match the chargeability of the toner and to destabilize the charging. Eliminate and prevent problems caused by toner degradation.

JP 2008-107442 A

  Here, in the developing device described in Patent Document 1, when the opening / closing operation of the control valve is small, it is possible to prevent the toner from returning from the developing unit to the toner cartridge, but sufficient toner supply from the toner cartridge to the developing unit is possible. Can't do at speed. On the other hand, when the opening / closing operation of the control valve is large, toner can be supplied from the toner cartridge to the developing unit at a sufficient speed, but the return of toner from the developing unit to the toner cartridge cannot be prevented.

  In view of the above circumstances, the present invention suppresses the return of toner from the third chamber to the first chamber and the replenishment of toner from the first chamber to the third chamber depending on the shape inside the apparatus. It is an object of the present invention to provide a developing device capable of performing the above.

  To achieve the above object, the present invention is provided in a first chamber for storing a one-component developer, a first opening formed in an upper portion of the first chamber, and the first chamber. A first chamber conveying member for supplying a one-component developer from the inside of the first chamber to the first opening, a second chamber connected to the first chamber via the first opening, A second opening formed at a position different from the first opening of the second chamber, and a third chamber connected to the second chamber via the second opening. The lower end of the first opening is set higher than the rotation center of the first chamber transfer member and the upper end of the second opening, and the lower end of the second opening is the third The angle formed by the bottom of the second opening and the horizontal line at the lower end of the second opening is a single component developer. Characterized in that it is set larger than the angle of repose.

  As described above, according to the present invention, the lower end of the first opening is set higher than the rotation center of the first chamber conveying member and the upper end of the second opening. From this, the return of toner from the third chamber to the first chamber can be suppressed.

  The lower end of the second opening is formed continuously with the bottom surface of the third chamber, and the angle at which the bottom surface of the developing chamber forms a horizontal line at the lower end of the second opening is greater than the repose angle of the one-component developer. It is set large. Thus, toner can be supplied from the first chamber to the third chamber at a sufficient speed.

  As a result, depending on the internal shape of the apparatus, the return of toner from the third chamber to the first chamber can be suppressed, and the toner can be supplied from the first chamber to the third chamber at a sufficient speed.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus to which a developing unit according to Embodiment 1 of the present invention is applied. FIG. 6 is a cross-sectional view of the process cartridge as viewed along the longitudinal direction (rotation axis direction) of the photosensitive drum. FIG. 6 is a side view showing the configuration of a toner storage chamber transport member in a state where a developing frame is removed. It is sectional drawing which shows the structure of the image development unit of a 1st comparative example and a 2nd comparative example. It is sectional drawing which shows the structure of the developing unit of a 3rd comparative example and a 4th comparative example. It is sectional drawing which shows the structure of the developing unit of a 5th comparative example and a 6th comparative example. FIG. 10 is a cross-sectional view illustrating a configuration of a process cartridge including a developing unit according to Embodiment 2. It is an expanded sectional view showing the composition of the development unit of the 7th comparative example. 6 is a cross-sectional view illustrating a configuration of a developing unit according to Embodiment 3. FIG. It is sectional drawing which shows the structure of a developing unit. It is a front view which shows the structure of a stirring member. 6 is a cross-sectional view illustrating a configuration of a developing unit according to Embodiment 4. FIG. It is sectional drawing which shows the structure of the modification of a developing unit. It is a partially expanded sectional view which shows the structure of the modification of a developing unit. It is the schematic etc. which show the various structures of 1st opening. It is a side view which shows the structure of the stirring member of Examples 2-4, and the structure of the modification.

  Hereinafter, exemplary embodiments of the present invention will be described in detail by way of example. However, since the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are appropriately changed according to the configuration of the mechanism to which the present invention is applied and various conditions, there are particularly specific descriptions. As long as there is not, it is not the meaning which limits the scope of the present invention only to them.

  FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus 100 to which a developing unit 4 according to Embodiment 1 of the present invention is applied. As shown in FIG. 1, the image forming apparatus 100 is a full-color laser beam printer that employs an inline method and an intermediate transfer method. The image forming apparatus 100 can form a full color image on a sheet (for example, recording paper, plastic sheet, cloth, etc.) based on the image information. The image information is obtained from an image reading apparatus connected to the image forming apparatus main body (hereinafter simply referred to as “apparatus main body 100A”) or a host device such as a personal computer connected to the image forming apparatus so as to be communicable. Is input.

  The image forming apparatus 100 includes a first image forming unit SY, a second image forming unit SM, and a third image forming unit for forming an image of each color of yellow (Y), magenta (M), cyan (C), and black (K). It has an image forming unit SC and a fourth image forming unit SK. In the first exemplary embodiment, the first to fourth image forming units SY to SK are arranged in a row inclined at a predetermined angle with respect to the vertical direction, and form an image on the intermediate transfer belt 5. The configurations and operations of the first to fourth image forming units SY to SK are substantially the same except that the colors of the images to be formed are different. Accordingly, in the following, unless there is a particular need to be distinguished, the subscripts Y, M, C, and K are omitted, and the image forming unit S will be collectively referred to. Regarding the omission of the suffixes Y, M, C, and K, the photosensitive drums 1Y to 1K, the charging rollers 2Y to 2K, the developing units 4Y to 4K, the cleaning members 6Y to 6K, and the process cartridges 7Y to 7K, which will be described later, The same shall apply. If the intermediate transfer method using the intermediate transfer belt 5 is not employed, the first to fourth image forming units SY to SK directly form images on the conveyed sheet.

  Each image forming unit S has a photosensitive drum 1 which is an “image carrier”. The photosensitive drum 1 is driven to rotate in the direction of arrow A, and is constituted by a drum-type electrophotographic photosensitive member. Around the photosensitive drum 1, a charging roller 2 as a “charging device”, a scanner unit 3 as an “exposure device”, a developing unit 4 as a “developing device”, and a cleaning member 6 as a “cleaning device” are arranged. Has been. The charging roller 2 is a roller that uniformly charges the surface of the photosensitive drum 1. The scanner unit 3 is a unit that forms an electrostatic image on the photosensitive drum 1 by irradiating a laser based on image information. The developing unit 4 is a unit that develops an electrostatic image as a toner image. The cleaning member 6 is a member that removes toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner).

  Further, an endless intermediate transfer belt 5, which is an “intermediate transfer member” for transferring the toner image on the photosensitive drum 1 to the sheet 12, is disposed at a position facing the four photosensitive drums 1. Yes. In the rotation direction of the photosensitive drum 1, the charging position by the charging roller 2, the exposure position by the scanner unit 3, the development position by the development unit 4, the transfer position of the toner image to the intermediate transfer belt 5, and the cleaning position by the cleaning member 6 are They are provided in this order.

  The developing unit 4 contains non-magnetic one-component toner as “non-magnetic one-component developer” which is “developer”. The developing unit 4 is assumed to perform reversal development by bringing a developing roller (described later) as a “developer carrying member” into contact with the photosensitive drum 1. The developing unit 4 exposes the toner charged to the same polarity (negative polarity in this embodiment) as the charged polarity of the photosensitive drum 1 on the surface of the photosensitive drum 1 to reduce the charge (image portion, exposure). Part). As a result, the electrostatic image on the surface of the photosensitive drum 1 is developed.

  The photosensitive drum 1, the charging roller 2 as process means acting on the photosensitive drum 1, the developing unit 4, and the cleaning member 6 are integrally formed into a cartridge to form a process cartridge 7. The process cartridge 7 can be attached to and detached from the image forming apparatus 100 via mounting means such as a mounting guide and a positioning member provided in the apparatus main body 100A. The process cartridges 7 for the respective colors have the same shape, and the process cartridges 7 for the respective colors have yellow (Y), magenta (M), cyan (C), and black (K) colors, respectively. Toner is contained. Although the process cartridge will be described, the developing unit 4 may be detachably attached to the apparatus main body.

  The intermediate transfer belt 5 is in contact with all the photosensitive drums 1 and circulates (rotates) in the direction of arrow B (counterclockwise). The intermediate transfer belt 5 is stretched around a plurality of support members (a driving roller 51, a secondary transfer counter roller 52, and a driven roller 53). Four primary transfer rollers 8, which are “primary transfer means”, are arranged in parallel on the inner peripheral surface side of the intermediate transfer belt 5 so as to face the respective photosensitive drums 1. The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photosensitive drum 1 to form a nip (primary transfer nip) at the primary transfer portion N1 where the intermediate transfer belt 5 and the photosensitive drum 1 are in contact with each other. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) which is a “primary transfer bias applying unit” (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  A secondary transfer roller 9, which is a “secondary transfer unit”, is disposed at a position facing the secondary transfer counter roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 9 is in pressure contact with the secondary transfer counter roller 52 via the intermediate transfer belt 5 and nips (secondary transfer nip) to the secondary transfer portion N2 where the intermediate transfer belt 5 and the secondary transfer roller 9 are in contact with each other. Form. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) as a secondary transfer bias applying unit (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondary transfer) to the sheet 12. The primary transfer roller 8 and the secondary transfer roller 9 have the same configuration.

  At the time of image formation, first, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2. Next, the surface of the charged photosensitive drum 1 is scanned and exposed by laser light corresponding to the image information emitted from the scanner unit 3, and an electrostatic image according to the image information is formed on the photosensitive drum 1. Next, the electrostatic image formed on the photosensitive drum 1 is developed as a toner image by the developing unit 4. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5 by the action of the primary transfer roller 8.

  For example, when forming a full-color image, the above-described processes are sequentially performed in the first to fourth image forming units SY to SK, and the toner images of the respective colors are sequentially superimposed and primarily transferred onto the intermediate transfer belt 5. The Thereafter, the movement of the intermediate transfer belt 5 is synchronized with the sheet 12, and the sheet 12 is conveyed to the secondary transfer portion N2. The four-color toner images on the intermediate transfer belt 5 are secondarily transferred onto the sheet 12 collectively by the action of the secondary transfer roller 9 that is in contact with the intermediate transfer belt 5 via the sheet 12. The sheet 12 to which the toner image is transferred is conveyed to a fixing device 10 as a fixing unit. The toner image is fixed on the sheet 12 by applying heat and pressure to the sheet 12 in the fixing device 10. The primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer step is removed by the cleaning member 6 and collected in a removed toner chamber (described later). The secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is cleaned by the intermediate transfer belt cleaning device 11. Note that the image forming apparatus 100 can also form a single-color or multi-color image using only a desired single or some (but not all) image forming units.

  FIG. 2A is a cross-sectional view of the process cartridge 7 as viewed along the longitudinal direction (rotational axis direction) of the photosensitive drum 1. The configuration and operation of the process cartridge 7 for each color are substantially the same except for the type (color) of the developer. As described above, the process cartridge 7 includes the photosensitive unit 13 including the photosensitive drum 1 and the developing unit 4 including the developing roller 17.

  The photoreceptor unit 13 includes a photoreceptor drum 1, a charging roller 2, and a cleaning frame body 14. The cleaning frame body 14 which is a “frame body” supports various internal components. The photosensitive drum 1 is rotatably attached to the cleaning frame body 14 via a photosensitive drum bearing (not shown), and the charging roller 2 is rotatably attached via a charging roller bearing (not shown). Further, a removal toner chamber 14 a is formed inside the cleaning frame body 14, and the cleaning member 6 is attached to the cleaning frame body 14. The photosensitive drum 1 receives a driving force of a driving motor (not shown), which is a “driving unit”, and can rotate in the direction of arrow A (the clockwise direction in FIG. 2A) according to the image forming operation. Yes. A charging roller 2 and a cleaning member 6 are arranged at a position facing the peripheral surface of the photosensitive drum 1 so as to be in contact with the photosensitive drum 1.

  The above-described removed toner chamber 14a is a chamber for storing the transfer residual toner when the transfer residual toner removed by the cleaning member 6 from the surface of the photosensitive drum 1 falls. The charging roller bearing described above is attached to the cleaning frame 14 and is movable along a line passing through the rotation center of the charging roller 2 and the rotation center of the photosensitive drum 1. The charging roller 2 is rotatably attached to the charging roller bearing. The charging roller bearing is urged toward the photosensitive drum 1 by a charging roller pressurizing spring (not shown) as an “urging means”.

  The developing unit 4 includes a developing frame 18, a supply roller 20, a developing roller 17, and a developing blade 21. The developing frame 18 which is a “frame” supports various internal components. A developing roller 17, which is a “developer carrier” that rotates in the direction of arrow D (counterclockwise) in contact with the photosensitive drum 1 is attached to the developing frame 18. That is, a developing side plate (not shown) is attached to each of both sides of the developing frame 18. The developing roller 17 is rotatably supported by the developing frame body 18 at both ends in the longitudinal direction (rotational axis direction) via the developing side plate. Further, the developing roller 17 and the photosensitive drum 1 rotate so that the surfaces of the developing roller 17 and the photosensitive drum 1 move in the same direction (in the present embodiment, the direction from the bottom to the top) in the facing portion (contact portion). Although the developing roller 17 is arranged in contact with the photosensitive drum 1, the developing roller 17 may be arranged close to the photosensitive drum 1 with a predetermined interval.

  The developing unit 4 is provided with a supply roller 20 that is a “developer supply body”, and the supply roller 20 rotates in the direction of arrow E (counterclockwise). The supply roller 20 is disposed so as to contact the circumferential surface of the developing roller 17. The supply roller 20 and the developing roller 17 rotate so that the surfaces of the supply roller 20 and the developing roller 17 move in opposite directions at the opposing portion (contact portion). The supply roller 20 has a function of supplying toner to the surface of the developing roller 17 and peeling off toner remaining on the surface of the developing roller 17 without being developed from the surface of the developing roller 17. Further, the developing unit 4 is provided with a developing blade 21 that is a “developer regulating member” that regulates the layer thickness of the toner supplied to the surface of the developing roller 17 by the supply roller 20. The developing blade 21 is disposed so as to contact the surface of the peripheral surface of the developing roller 17.

  A developing frame 18 that is a “developing device body” includes a toner storage chamber 18 a that is a “first chamber” that stores a one-component developer, a buffer chamber 18 c that is a “second chamber”, and a “third chamber”. A developing chamber 18b is formed. The toner storage chamber 18a stores nonmagnetic one-component toner as “nonmagnetic one-component developer” which is “developer”. Further, a toner storage chamber transport member 22 that is a “first chamber transport member” is supported inside the toner storage chamber 18 a so as to be rotatable with respect to the developing device frame 18. The toner storage chamber transport member 22 has a function of stirring the toner stored in the toner storage chamber 18a and transporting the toner to the buffer chamber 18c. Here, the toner storage chamber conveyance member 22 uses the outside of the buffer chamber 18c as a rotation region. Note that the present invention can also be applied to a developer container (toner cartridge) that includes only the toner storage chamber 18a and the toner storage chamber conveyance member 22 and is detachable from the apparatus main body 100A. The developing unit 4 is swingably coupled to the photosensitive unit 13 around a coupling shaft (not illustrated) that fits into a hole (not illustrated) provided in the developing side plate (not illustrated). At the time of image formation, the developing unit 4 is urged by a developing unit pressure spring 24 that is an “urging means” and rotates clockwise about a coupling shaft (not shown). As a result, the developing roller 17 comes into contact with the photosensitive drum 1.

[Toner Conveying Configuration from Toner Storage Chamber 18a to Buffer Chamber 18c]
A configuration in which the one-component toner is transported from the toner storage chamber 18a to the buffer chamber 18c inside the developing unit 4 of the process cartridge 7 according to the first embodiment will be described. Regarding the configuration and operation of the developing unit 4 or the process cartridge 7, terms indicating directions such as up, down, vertical, and horizontal represent directions when viewed in their normal use state unless otherwise specified. . That is, the normal use state of the developing unit 4 or the process cartridge 7 is a state in which the developing unit 4 or the process cartridge 7 can be properly attached to the properly arranged apparatus main body 100A and used for an image forming operation.

  The developing chamber 18b accommodates a developing roller 17, a supply roller 20, a developing blade 21, and the like. One-component toner supplied to the buffer chamber 18c is stored in the toner storage chamber 18a. Inside the toner storage chamber 18a, a toner storage chamber transport member 22 that is a “first chamber transport member” for supplying toner into the buffer chamber 18c is provided. The toner storage chamber 18a is disposed below the buffer chamber 18c in the vertical direction. Between the buffer chamber 18c and the toner storage chamber 18a, a partition wall 26 having a first opening 44 which is a “first opening” through which toner passes is disposed. The first opening 44 is formed in the upper part of the toner storage chamber 18a. Therefore, the toner needs to be conveyed from the toner storage chamber 18a to the buffer chamber 18c against gravity.

  An elastic toner storage chamber transport member 22 is rotatably provided in the toner storage chamber 18a so as to supply one-component toner from the toner storage chamber 18a to the buffer chamber 18c through the first opening 44. It has been. The toner storage chamber transport member 22 is supported by a transport support shaft 22b whose base end is the “rotation center”, and a sheet portion 22a extends from the base end to the front end. The toner storage chamber transport member 22 has a fixed end at the base end and a free end at the tip end. The lower end 44 a of the first opening 44 is set higher than the transport support shaft 22 b of the toner storage chamber transport member 22 and the upper end 45 a of the second opening 45. The supply of toner from the buffer chamber 18c to the developing chamber 18b will be described later.

  A guide portion 18a2 and a restoring portion 18a4 are formed in the toner storage chamber 18a. A boundary between the guide portion 18a2 and the restoration portion 18a4 is a boundary portion 18a3. First, the guide portion 18a2 is a straight portion of the inner wall of the toner storage chamber 18a and points to a boundary line portion 18a3 where the toner storage chamber conveyance member 22 is separated from the lower corner portion J. The guide portion 18a2 is disposed below the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c, and functions as a “deformation portion” that deforms in contact with the toner storage chamber conveyance member 22. As the toner storage chamber transport member 22 rotates, it abuts against the guide portion 18a2 and receives force from the guide portion 18a2. As a result, the toner storage chamber transport member 22 is deformed against the elastic force of the toner storage chamber transport member 22. Further, since the toner storage chamber conveyance member 22 rotates while being in contact with the guide portion 18a2, the toner storage chamber conveyance member 22 conveys the toner to the downstream side in the rotation direction.

  Next, the restoring portion 18a4 is a straight portion of the inner wall of the toner storage chamber 18a, and refers to a portion from the boundary line portion 18a3 where the toner storage chamber conveyance member 22 is separated to the upper corner K which is obliquely above. In other words, the restoring portion 18 a 4 is provided inside the toner storage chamber 18 a and downstream of the guide portion 18 a 2 and upstream of the first opening 44 in the rotation direction of the toner storage chamber transport member 22. The restoration unit 18a4 functions as an “opening unit” that opens the contact between the toner storage chamber conveyance member 22 and the inner wall of the toner storage chamber 18a. More specifically, the restoring portion 18a4 is disposed above the horizontal plane including the rotation axis of the toner storage chamber transport member 22. The boundary line 18a3 is provided at the same height as the horizontal plane passing through the rotation center of the toner storage chamber transport member 22 or above the horizontal plane.

  Due to the presence of such a restoring portion 18a4, the toner storage chamber transport member 22 operates as follows. When the toner storage chamber transport member 22 rotates, the tip 22c of the toner storage chamber transport member 22 moves while contacting and bending the guide portion 18a2, and when the toner storage chamber transport member 22 passes through the boundary portion 18a3, the toner by the toner storage chamber transport member 22 is moved. The contact with the inner wall of the storage chamber 18a is released. That is, the toner storage chamber transport member 22 is released from the deformed state by the guide portion 18a2, and is restored to its original shape by the elastic restoring force of the sheet portion 22a. In addition, the toner carried on the surface of the toner storage chamber transport member 22 by the restoring force to restore the shape of the toner storage chamber transport member 22 against the gravity, It flies to the 1st opening 44 between the chamber 18a and the buffer chamber 18c. The first opening 44 between the toner storage chamber 18a and the buffer chamber 18c is located downstream of the restoring portion 18a4 in the toner transport direction.

  The boundary line portion 18a3 corresponds to the boundary between the guide portion 18a2 and the restoration portion 18a4. The boundary portion 18a3 is provided below the lower end 44a of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c. When the toner storage chamber transport member 22 moves away from the boundary line portion 18a3, the toner storage chamber transport member 22 is rotated to a position where it can come into contact with the periphery of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c due to its elastic recovery. is doing. Therefore, at the moment when the toner storage chamber transport member 22 is separated from the boundary portion 18a3, the toner storage chamber transport member 22 hits the periphery of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c by its elastic force. . As a result, the toner can surely fly to the first opening 44.

  The toner storage chamber transport member 22 is rotatably supported by the developing frame 18 that forms the toner storage chamber 18a at both ends in the longitudinal direction (rotation axis direction). The toner storage chamber conveyance member 22 is rotationally driven in a direction indicated by an arrow G (clockwise) by a drive unit (drive source) (not shown).

  The toner storage chamber conveying member 22 includes a flexible sheet portion 22a serving as a conveying portion for conveying toner, and a conveyance support shaft (rotating shaft) to which the sheet portion 22a is attached and receives a rotational driving force. ) 22b. The conveyance support shaft 22b is disposed over the entire region in the longitudinal direction of the toner storage chamber 18a substantially parallel to the longitudinal direction (rotational axis direction) of the photosensitive drum 1, the developing roller 17, and the supply roller 20. The sheet portion 22a is a continuous sheet (plate-like member) that extends over substantially the entire region in the longitudinal direction (rotational axis direction) of the conveyance support shaft 22b. The sheet portion 22a is attached to the conveyance support shaft 22b at one end in a direction (rotational radius direction) substantially orthogonal to the longitudinal direction of the conveyance support shaft 22b.

  The sheet portion 22a can be suitably manufactured using a flexible resin sheet such as a polyester film, a polyphenylene sulfide film, or a polycarbonate film. The thickness of the sheet portion 22a is preferably 50 μm to 250 μm.

  The length L1 from the center of the conveyance support shaft 22b which is the “rotation center” of the toner storage chamber conveyance member 22 to the free end of the sheet portion 22a is a straight line from the center of the conveyance support shaft 22b to the lower end 44a of the first opening 44. It is set to be larger than the distance L2. The lower end 44a corresponds to the lowest point of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c. Here, the above-described length L1 corresponds to the maximum value of the rotation radius of the toner storage chamber transport member 22 in a natural state where the sheet portion 22a is not deformed. As a result, the toner can be more reliably sent to the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c.

  The toner storage chamber 18a and the buffer chamber 18c are connected via a first opening 44 that is a “first opening”, and the buffer chamber 18c and the developing chamber 18b are a second opening 45 that is a “second opening”. Are connected through. The second opening 45 is formed at a position different from the first opening 44 around the buffer chamber 18c. A lower end 45b of the second opening 45 is formed continuously with the developing chamber bottom surface 26c of the developing chamber 18b. The angle formed by the lower end 45b of the second opening 45 and the developing chamber bottom surface 26c of the developing chamber 18b with the horizontal line a is set to be larger than the repose angle of the one-component developer. The developing frame 18 is formed with a partition wall 26 including the developing chamber bottom surface 26c. The partition wall 26 partitions the developing chamber 18b and the toner storage chamber 18a, and the buffer chamber 18c and the toner storage chamber. Between 18a is divided. The partition wall 26 is formed in a concave shape below the supply roller 20. The partition wall 26 includes a developing chamber bottom surface 26c below the supply roller 20, a developing chamber bottom surface 26f below the developing blade 21, a buffer chamber bottom surface 26d positioned below the buffer chamber 18c, a toner storage chamber 18a, and a buffer chamber 18c. And a partition wall 26e for partitioning.

[Single component developer]
Next, the toner used in Example 1 will be described. The toner of Example 1 has a volume average particle size of 4.0 μm or more and 10.0 μm or less, and an average circularity of 0.950 or more. When the volume average particle diameter of the toner of this embodiment is less than 4 μm, the chargeability due to the deterioration of the fluidity of the toner particles tends to be non-uniform, for example, image fogging easily occurs in a high humidity environment. Therefore, there is concern. Further, when the volume average particle diameter of the toner exceeds 10 μm, high-definition output becomes difficult, and there is a concern that the required image quality cannot be satisfied.

  For example, a Coulter Counter TA-II type or Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) is used to measure the volume average particle diameter of the toner. The volume average particle diameter of the toner T can be measured with a measuring device in which an interface (manufactured by Nikka Ki Bios Co., Ltd.) for outputting the number distribution and volume distribution and a personal computer are connected. In this measurement, an electrolytic solution is used. For this electrolytic solution, for example, a 1% NaCl aqueous solution prepared using primary sodium chloride or ISOTON R-II (manufactured by Coulter Scientific Japan Co., Ltd.) can be used. .

  As a measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant in an electrolytic aqueous solution of 100 to 150 ml, and further 2 to 20 mg of a measurement sample is added. The electrolytic solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser, and the volume distribution is determined by measuring the volume of toner of 2 μm or more with the Coulter Counter TA-II type using an aperture of 100 μm as an aperture. calculate. Then, the volume average particle diameter obtained from the volume distribution of this example is obtained.

  For the shape control of the toner of the present embodiment, it is preferable that the average circularity of the toner in the equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring apparatus is 0.950 or more. A toner having an average circularity of less than 0.950 means a toner whose shape has moved away from a spherical shape and has approached an indeterminate shape. Such irregular shaped toner tends to be crushed in the developing device during development, so that the particle size distribution fluctuates or the charge amount distribution becomes broad. This is not preferable because an undesired phenomenon such as an increase tends to occur.

  The circularity of the toner in this embodiment is used as a simple method for quantitatively expressing the shape of the toner particles. In the present Example, it measured using the flow type particle image measuring device FPIA-1000 type | mold (Toa Medical Electronics (made by Sysmex) Corporation), and computed using the following Formula. The measurement conditions were such that the toner particle concentration during measurement was adjusted to 5000 to 15000 particles / μl, and 1000 or more toner particles were measured. Circularity = (peripheral length of a circle having the same area as the particle projection area) / (peripheral length of the particle projection image). Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add about 0.02 g of sample and disperse uniformly. As a means to disperse, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a titanium alloy tip of φ5 mm as a vibrator is used. A dispersion is obtained.

  As an achievement means for bringing the volume average particle diameter and the average circularity of the present embodiment into the preferred ranges of the present invention, in addition to a production method by a so-called pulverization method, a toner is produced using the following method or the like. It is also possible. That is, a method of directly producing toner using the suspension polymerization method disclosed in JP-A-36-10231 and JP-A-59-53856, or a heavy polymer that is soluble in a monomer. This is a dispersion polymerization method in which a toner is directly produced using a water-based organic solvent in which the coalescence is insoluble. Further, it is an emulsion polymerization method typified by a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator.

  In this embodiment, the shape of the toner can be easily controlled, and a suspension polymerization under normal pressure or under pressure, which can relatively easily obtain a fine particle toner having a sharp particle size distribution and a volume average particle size of 4 to 10 μm. The method was used. Then, styrene and n-butyl acrylate as monomers, a salicylic acid metal compound as a charge control agent, a saturated polyester as a polar resin, and a wax and a colorant were added to produce colored suspended particles. The toner particles have a volume average particle diameter of 6.5 μm and an average circularity of 0.980.

  Subsequently, the external additive attached to the developer base particles (hereinafter referred to as toner base particles), which is a feature of this embodiment, will be described below. Silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are 1.0 part by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of toner base particles (100 parts by mass of developer base particles). It is attached. Further, fine particles other than silica having an average primary particle size of 5 nm or more and less than 500 nm are externally added in an amount of less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles.

  When silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are not externally added, good toner fluidity cannot be obtained, and it becomes difficult to sufficiently charge the toner particles. Concerned. If good toner fluidity cannot be obtained, and toner particles are not sufficiently charged, there is a concern that problems such as increased fog, decreased image density, and toner scattering are likely to occur. .

  When silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to less than 1.0 part by mass with respect to 100 parts by mass of the toner base particles, when the developer is used for a long period of time, There is a concern that good toner fluidity cannot be obtained in the latter half of use of the developing unit. In such a case, there is a concern that it is difficult to sufficiently charge the toner particles. If the toner particles are not sufficiently charged, problems such as an increase in fog, a decrease in image density, and toner scattering are likely to occur.

  In addition, when silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to 3.0 parts by mass or more with respect to 100 parts by mass of the toner base particles, silica on the surface of the photoreceptor or developer carrying member There is a concern that contamination is likely to occur. When silica contamination occurs on the surface of the photosensitive member or the developer carrying member, it causes development problems due to fusion to the surface of the photosensitive member or contamination of the lower layer of the developer carrying member in continuous printing of images. There is concern.

  Thus, silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to 1.0 part by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the toner base particles. Good toner fluidity can be obtained. Therefore, it is possible to sufficiently charge the toner particles.

  Here, in order to maintain the performance of each process of development, transfer, fixing, and cleaning, a small amount of other fine particles may be externally added to finely adjust the fluidity and chargeability of the toner. However, if the average primary particle size of the fine particles is 500 nm or more, it is easy to detach from the toner surface, and it becomes difficult to maintain the fluidity and chargeability of the toner for a long period of time, so the average primary particle size is 5 nm or more and less than 500 nm. It is preferable to externally add the fine particles.

  In addition, when fine particles having an average primary particle size of less than 5 nm are externally added, the fine particles have a high cohesive property and have a wide particle size distribution having a strong cohesive property that is difficult to break even by crushing treatment instead of the primary particles. It tends to behave as an aggregate. For this reason, there is a concern that the image may become defective due to development of the aggregate, damage to the fixing member, the image carrier, the developer carrier, or the like.

  In general, if the fine particles having an average primary particle size of 5 nm or more and less than 500 nm are externally added to less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles, the average primary particle size is 5 nm or more and less than 100 nm. The effect of silica fine particles is great. Therefore, good toner fluidity and chargeability can be obtained. Thereby, a sufficiently good image can be output.

  Examples of the fine particles having an average primary particle size of 5 nm or more and less than 500 nm include the following. It is a lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder. It is also an abrasive such as cerium oxide powder, silicon carbide powder, strontium titanate powder. It is also a fluidity-imparting agent such as titanium oxide powder or aluminum oxide powder. It is also an anti-caking agent. In addition, it is a cleaning aid such as fine particles close to an inorganic or organic sphere such as spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles. In addition, organic fine particles having opposite polarity and inorganic fine particles can be used in small amounts as a developability improver. These additives can also be used after hydrophobizing the surface.

  A method for measuring the average primary particle size of the external additive fine particles in this example is described below. It is a photograph of the toner magnified with a scanning electron microscope, and contrasted with a photograph of the toner mapped with the elements contained in the external additive fine particles by elemental analysis means such as XMA attached to the scanning electron microscope. Done. Then, while comparing these photographs, 100 or more primary particles of the external additive fine particles adhering to or liberating from the toner surface are measured, and the number average particle diameter is obtained.

  The silica fine particles are preferably hydrophobized. For example, the surface of silica fine particles can be hydrophobized by treating with silicone oil. Silica fine particles are generally added to improve the fluidity of the toner and to make the toner base particles uniformly charged. By treating the inorganic fine particles with a silicone oil as in this embodiment, the following functions are achieved. Can be granted. The functions include not only adjustment of the toner charge amount and environmental stability, but also improvement of releasability from the fixing belt of this embodiment. It is more preferable that the silica fine particles are hydrophobized in order to keep the charge amount of the toner particles high even in a high-humidity environment and to prevent toner scattering.

  Here, 1.5 parts by mass of silica A having an average primary particle diameter of 10 nm and 0.4 parts by mass of silica B having an average primary particle diameter of 50 nm are weighed with respect to 100 parts by mass of the toner base particles, and dry-processed with a Henschel mixer. By mixing, toners of Examples and Comparative Examples were obtained.

FIG. 2B is an explanatory diagram for explaining an example of a method for measuring the angle of repose of the toner. In Example 1, a one-component toner having an angle of repose of 30 ° is used. The angle of repose θ of the one-component toner is derived, for example, by the following method. As a measuring apparatus, for example, a powder tester PT-N type (Hosokawa Micron Corporation) was used. The measurement method conforms to the measurement of the angle of repose in the instruction manual attached to the powder tester PT-N type (the opening of the sieve 61 is 710 μm, the vibration time is 180 s, and the amplitude is 2 mm or less). The toner is dropped from the funnel 62 onto the disk 63, and the angle formed between the generatrix of the toner 64 deposited on the disk 63 and the surface of the disk 63 is determined as the repose angle. However, after the sample is left to stand overnight at a temperature of 23 ° C. and a relative humidity of 50% (hereinafter referred to as 50% RH), the measurement apparatus is in an environment where the temperature is 23 ° C. and the relative humidity is 50% RH. The angle of repose is measured with, and the value obtained by repeating the measurement five times and taking the arithmetic average is defined as θ. The toner volume resistance value of this toner is 10 ¹⁴ Ω · cm or more. The measurement conditions of the volume resistance value of the toner are: diameter φ = 6 mm, measurement electrode plate area = 0.283 cm ² , pressure = 1500 g weight, pressure = 96.1 kPa, powder layer thickness at measurement = 0.5 It was set to -1.0 mm. Then, a 400V DC voltage was measured with a microammeter (YHP (Yokogawa Hewlett-Packard Co., Ltd.) 4140pA / METER / DC / VOLTAGE / SOUCE), and the volume resistance value (specific resistance) from the measured current value. Is calculated.

  FIG. 3A is a side view showing the configuration of the toner storage chamber transport member 22 with the developing frame 18 removed as viewed from the direction of the arrow V shown in FIG. The length M in the longitudinal direction of the sheet portion 22a is preferably longer than the length N in the longitudinal direction of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c. As shown in FIG. 3A, the toner supply path that continues from the buffer chamber 18 c to the developing chamber 18 b is connected via the first opening 44. When the toner storage chamber conveyance member 22 rotates inside the toner storage chamber 18a, the toner flies to the first opening 44 by the sheet portion 22a.

  FIG. 3B is a cross-sectional view showing the positional relationship between the buffer chamber 18c and the developing chamber 18b. A partition wall 43 and a second opening 45 are formed between the buffer chamber 18c and the developing chamber 18b. The lower end of the partition wall 43 corresponds to the upper end 45 a of the second opening 45. Here, an intersection where a vertical line passing through the upper end 45a of the second opening 45 intersects the developing chamber bottom surface 26c of the developing chamber 18b is defined as a lower end 45b of the second opening 45 of the buffer chamber 18c and the developing chamber 18b. Therefore, the lower end 45b of the second opening 45 between the buffer chamber 18c and the developing chamber 18b serves as a boundary between the developing chamber bottom surface 26c and the buffer chamber bottom surface 26d below the supply roller 20.

  A second opening 45 is provided on the opposite side of the contact portion between the supply roller 20 and the developing roller 17 across the supply roller 20. Through the second opening 45, the toner inside the buffer chamber 18c is supplied to the developing chamber 18b.

  The supply roller 20 rotates in a direction in which the surface moves from the upper side to the lower side at a portion facing the second opening 45. That is, the supply roller 20 rotates so as to take in the toner supplied from the second opening 45 to the developing chamber 18 b downward along the developing chamber bottom surface 26 c below the supply roller 20. The lower end 45 b of the second opening 45 is disposed above the lower end of the supply roller 20.

  The angle β at which the tangent line b of the developing chamber bottom surface 26c at the lower end 45b of the second opening 45 intersects the horizontal line a is set to 55 °. As described above, the repose angle of the non-magnetic one-component toner used in Example 1 is 30 °. Therefore, when there is sufficient toner in the developing chamber 18b near the second opening 45, the toner does not move from the buffer chamber 18c to the developing chamber 18b. However, when there is no toner in the developing chamber 18b near the second opening 45, the toner inside the buffer chamber 18c near the lower end 45b of the second opening 45 moves from the buffer chamber 18c to the developing chamber 18b. Since the toner falls, the toner moves from the buffer chamber 18c to the developing chamber 18b. Therefore, the height of the toner surface inside the developing chamber 18 b is always kept at the lower end 45 b or more of the second opening 45. Further, the surface of the toner is disposed above the lower end of the supply roller 20. Therefore, the contact area between the surface of the supply roller 20 and the toner increases, and the efficiency of supplying the toner to the supply roller 20 is improved.

  The principle of preventing the toner from returning from the developing chamber 18b to the toner storage chamber 18a will be described below. At the initial use of the developing unit 4, the toner storage chamber 18a is filled with a predetermined amount of toner, and the buffer chamber 18c and the developing chamber 18b have no toner. When the use of the developing unit 4 is started from that state, the toner is sequentially sent to the toner storage chamber 18a, the buffer chamber 18c, and the developing chamber 18b. Then, the heights of the toner agent surfaces of the developing chamber 18b and the buffer chamber 18c are accumulated until they are approximately equal to the height of the lower end 44a of the first opening 44.

  The toner surface that accumulates in the buffer chamber 18 c only accumulates to the same extent as the height of the lower end 44 a of the first opening 44. Therefore, the toner that cannot be stored in the buffer chamber 18c falls to the lower portion of the toner storage chamber 18a. The lower end 44a of the first opening 44 is set to be higher than the conveyance support shaft 22b, which is the “rotation center” of the toner storage chamber conveyance member 22, and the conveyance of the toner from the toner storage chamber 18a is conveyance by toner flight. Therefore, a large powder pressure is not applied to the toner inside the buffer chamber 18c. For this reason, the toner in the toner storage chamber 18a and the buffer chamber 18c is mixed only in the vicinity of the toner agent surface of the buffer chamber 18c. Further, the toner in the buffer chamber 18c is prevented from returning to the toner storage chamber 18a due to the toner conveyance from the toner storage chamber 18a. Further, the toner inside the buffer chamber 18c can only move downward due to its own weight. Thus, since toner does not circulate up and down inside the buffer chamber 18c, toner does not mix up and down inside the buffer chamber 18c.

  The lower end 44 a of the first opening 44 is higher than the upper end 45 a of the second opening 45. For this reason, the toner agent surface is not connected from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. That is, the toner inside the developing chamber 18b does not return to the toner storage chamber 18a unless it passes through the second opening 45 between the buffer chamber 18c and the developing chamber 18b below the toner agent surface. However, as described above, toner is not mixed up and down in the buffer chamber 18c. Therefore, the toner inside the developing chamber 18b does not return to the toner storage chamber 18a.

  The toner inside the buffer chamber 18c is slightly vibrated under the influence of the rotation of the supply roller 20, and does not form a non-moving layer. Accordingly, when there is no toner in the developing chamber 18b in the vicinity of the second opening 45, the toner in the buffer chamber 18c near the lower end 45b of the second opening 45 is easily transferred from the buffer chamber 18c to the developing chamber 18b. Therefore, the toner moves from the buffer chamber 18c to the developing chamber 18b. Further, since the toner in the buffer chamber 18c is vibrated minutely by the rotation of the supply roller 20, the toner in the buffer chamber 18c is not clogged, and the toner is supplied from the toner storage chamber 18a to the developing chamber 18b. Will not be disturbed.

(First comparative example)
FIG. 4A is a cross-sectional view illustrating a configuration of the developing unit 104 of the first comparative example. The developing unit 104 of the first comparative example is different from the developing unit 4 of Example 1 in that the buffer chamber 18c is not provided and an opening valve 42 is provided between the toner storage chamber 18a and the developing chamber 18b. An angle β ′ formed by the tangent line b of the developing chamber bottom surface 26c below the supply roller 20 and the horizontal line a at the lower end 50a of the opening 50 between the toner storage chamber 18a and the developing chamber 18b is 60 °. The opening valve 42 between the toner storage chamber 18a and the developing chamber 18b is in contact with the developing chamber bottom surface 26c below the supply roller 20, and the opening 50 is closed in a normal state. The opening valve 42 has elasticity. The opening valve 42 is disposed so as not to contact the toner storage chamber transport member 22. Only when the toner is conveyed to the vicinity of the opening valve 42 by the toner storage chamber conveying member 22, the opening valve 42 is elastically deformed and the opening 50 is opened.

(Second comparative example)
FIG. 4B is a cross-sectional view showing the configuration of the developing unit 204 of the second comparative example. The developing unit 204 of the second comparative example is different from the developing unit 4 of Example 1 in that the buffer chamber 18c is not provided and an opening valve 42 is provided between the toner storage chamber 18a and the developing chamber 18b. The angle β ′ formed by the tangent line b of the developing chamber bottom surface 26c at the lower end 50a of the opening 50 between the toner storage chamber 18a and the developing chamber 18b with the horizontal line a is 60 °. The opening valve 42 is in contact with the developing chamber bottom surface 26c below the supply roller 20, and the opening 50 is closed in a normal state. The opening valve 42 has elasticity. The opening valve 42 includes an opening valve protrusion 42a on the surface of the toner storage chamber 18a, and the toner storage chamber conveyance member 22 is configured to have a size capable of contacting the opening valve protrusion 42a. When the tip of the toner storage chamber conveying member 22 contacts the opening valve protrusion 42a, the opening valve 42 is elastically deformed and the opening 50 is opened.

(Third comparative example)
FIG. 5A is a cross-sectional view showing a configuration of the developing unit 304 of the third comparative example. The developing unit 304 of the third comparative example is different from the developing unit 4 of Example 1 in that the lower end 44a of the first opening 44 is lower than the upper end 45a of the second opening 45.

(Fourth comparative example)
FIG. 5B is a cross-sectional view showing a configuration of the developing unit 404 of the fourth comparative example. In the developing unit 404 of the fourth comparative example, the lower end 44a of the first opening 44 is lower than the transport support shaft 22b of the toner storage chamber transport member 22, and the leading end of the sheet portion 22a of the toner storage chamber transport member 22 is in the buffer chamber 18c. It differs from the developing unit 4 of Embodiment 1 in that it enters the inside.

(Fifth comparative example)
FIG. 6A is a cross-sectional view showing the configuration of the developing unit 504 of the fifth comparative example. In the developing unit 504 of the fifth comparative example, the lower end 44a of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c is more than the transport support shaft 22b that is the “rotation center” of the toner storage chamber transport member 22. It differs from the developing unit 4 of the first embodiment in that it is low.

(Sixth comparative example)
FIG. 6B is a cross-sectional view illustrating a configuration of the developing unit 604 of the sixth comparative example. The developing unit 604 of the sixth comparative example is different from the developing unit 4 of Example 1 in the following points. In the developing unit 604, the angle β ′ at which the tangent line b of the developing chamber bottom surface 26c below the supply roller 20 at the lower end 45b of the second opening 45 between the buffer chamber 18c and the developing chamber 18b forms with the horizontal line a is the rest of the toner. It differs from the developing unit 4 of the first embodiment in that it is smaller than the corner. The angle β ′ formed with the horizontal surface of the bottom surface 26c of the developing chamber below the supply roller 20 at the lower end 45b of the second opening 45 is 15 °, and the repose angle of the toner is 30 °.

  The return of toner from the developing chamber 18b to the toner storage chamber 18a was evaluated by the following method. When there is no return of toner from the developing chamber 18b to the toner storage chamber 18a, the toner inside the toner storage chamber 18a can maintain a new state. On the contrary, when the toner returns from the developing chamber 18b to the toner storing chamber 18a, the toner deteriorated in the developing chamber 18b is mixed into the toner storing chamber 18a, so that the toner inside the toner storing chamber 18a is in a new state. It cannot be maintained. Therefore, an endurance test close to actual use conditions is performed, and toner deterioration of the toner inside the toner storage chamber 18a is evaluated to evaluate the return of toner from the developing chamber 18b to the toner storage chamber 18a.

  This will be described in detail below. The toner storage chamber 18a was filled with 200 g of toner corresponding to 8000 A4 size images with an image printing ratio of 5%, and a durability test was performed. The image for evaluation was an A4 size character pattern with an image printing ratio of 1%. The intermittent mode is set to stop for 5 seconds once every time two images are output. The test environment was a temperature of 23 ° C. and a humidity of 50% RH.

  After printing a character pattern up to 24,000 images, the toner inside the developing unit was 80 g. If the toner in the developing unit is 80 g, the toner can be collected from the inside of the toner storage chamber 18a in any of Example 1 and the first to sixth comparative examples. Under the conditions at this time, the toner deterioration of the toner inside the toner storage chamber 18a was evaluated. That the external additive is liberated from the surface of the toner base particles or the external additive is embedded in the toner base particles is called toner deterioration. When toner deterioration occurs, the specific surface area of the toner surface decreases and approaches the non-externally added toner (toner base particles). Therefore, in order to evaluate the degree of toner deterioration, the BET specific surface area of the toner was measured.

  The BET specific surface area of the toner in the present invention is measured using a degassing device Bacuprep 061 (manufactured by Micromeritic) and a BET measuring device Gemini 2375 (manufactured by Micromeritic). The specific measurement procedure is described in the operation manual of the measurement apparatus such as Gemini 2375 (V5.0) in the instruction manual, and is as follows.

  It is a sample preparation procedure. First, after measuring the weight of an empty sample cell, it is filled with a measurement sample (in the case of toner, so as to fall between 1.00 and 1.01 g), and the degassing apparatus is A sample cell filled with a sample is set, and degassing is performed at room temperature for 3 hours. After completion of degassing, the mass of the entire sample cell is measured, and the accurate mass of the sample is calculated from the difference from the empty sample cell.

  A procedure for measuring the BET specific surface area will be described. First, empty sample cells are set in the balance port and analysis port of the BET measuring device. Next, a Dewar bottle containing liquid nitrogen is set at a predetermined position, and P0 is measured by a saturated vapor pressure (P0) measurement command. After the P0 measurement is completed, the prepared sample cell is set in the analysis port, the sample mass and P0 are input, and the measurement is started by the BET measurement command. After that, the BET specific surface area is automatically calculated. The method for measuring the BET specific surface area is a dynamic constant pressure method based on the ISO 9277 (1995) standard.

The evaluation of toner deterioration was performed according to the following criteria. S1 = uncoated BET specific surface area of the toner (toner base ^{particles) [m 2 / g],} S2 = is defined as external addition already BET specific surface area of the new toner ^[m 2 / g]. S3 = BET specific surface area [m2 / g] of toner collected from the toner storage chamber 18a after the durability test, and (S3-S1) / (S2-S1) is defined as a toner deterioration index.

  “Good” indicates that the toner deterioration index is 0.8 or more, “X” indicates a problem, and the toner deterioration index is less than 0.8. When toner deterioration occurs, the specific surface area of the toner surface decreases and approaches the non-externally added toner (toner base particles). Accordingly, if the toner inside the toner storage chamber 18a after the durability test has not deteriorated, the toner deterioration index is 1. Conversely, the toner deterioration index approaches 0 as the toner in the toner storage chamber 18a after the durability test deteriorates. Here, if the toner deterioration index can be maintained at 0.8 or more, a new toner can be supplied to the developing chamber 18b from the toner storage chamber 18a, and a developing device that can be used stably over a long period of time is provided. can do.

[Method for Evaluating Supply of Toner from Toner Storage Chamber 18a to Development Chamber 18b]
Next, the supply of toner from the toner storage chamber 18a to the developing chamber 18b was evaluated by the following method. The toner consumption rate from the developing chamber 18b is the fastest when continuous images are output continuously. If the toner supply speed from the toner storage chamber 18a to the development chamber 18b is insufficient, the toner consumption speed inside the development chamber 18b is higher than the toner supply speed from the toner storage chamber 18a to the development chamber 18b. In addition, toner shortage inside the developing chamber 18b occurs. If the amount of toner in the developing chamber 18b is too small, when a solid image is output, the solid image is whitened due to insufficient toner. In the present invention, even if solid images are output continuously, the solid image is realized so that it does not fall out white due to toner shortage.

  Therefore, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is evaluated by continuously outputting solid images and checking the presence or absence of image defects in the solid images. The evaluation will be described in detail below. A solid image continuous output test was conducted by filling the toner storage chamber 18a with 200 g of toner corresponding to 8000 A4 size images with an image printing ratio of 5%. The evaluation image was an A4 size solid image with an image printing ratio of 100%. The test environment was a temperature of 23 ° C. and a humidity of 50% RH.

  After 400 solid images were printed, continuous solid image output was stopped, but the toner amount inside the developing unit 4 was 80 g. Next, image evaluation of 400 printed solid images was performed. The presence or absence of an image defect in which all or part of the solid image is white was confirmed. If the amount of toner in the developing unit 4 was able to print a solid image from 200 g in the initial use to 80 g in the latter half of the use, it was evaluated that the toner supply from the toner storage chamber 18 a to the development chamber 18 b was sufficient.

  The evaluation of toner supply was performed according to the following criteria. ○ is good and there is no occurrence of an image defect in which the solid image is whitened. △ is almost good and an image defect in which a part of the solid image is slightly whitened is generated. × is a problem. An image defect in which all or a part of the image is markedly white is considered to have occurred.

[Evaluation results of Example 1 and first to sixth comparative examples]
Table 1 is a table showing the evaluation results of Example 1 and the first to sixth comparative examples.

表１に示されるように、実施例１の現像ユニット４では、現像室１８ｂからトナー収納室１８ａへのトナーの戻り防止に関しては良好（○）である。また、トナー収納室１８ａから現像室１８ｂへのトナーの供給に関してはほぼ良好（△）である。実施例１では、供給ローラ２０は、バッファ室１８ｃ及び現像室１８ｂの間の第２開口４５に対向する対向部分の表面が、上から下へと回転する。また、第２開口４５の下端４５ｂは、供給ローラ２０の下端よりも上方に配置される。これにより、供給ローラ２０は、第２開口４５から現像室１８ｂに供給されたトナーを、現像室底面２６ｃに沿って供給ローラ２０の下方に取り込みながら回転する。

As shown in Table 1, in the developing unit 4 of Example 1, the prevention of toner return from the developing chamber 18b to the toner storage chamber 18a is good (◯). Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is almost good (Δ). In the first embodiment, the surface of the supply roller 20 facing the second opening 45 between the buffer chamber 18c and the developing chamber 18b rotates from top to bottom. Further, the lower end 45 b of the second opening 45 is disposed above the lower end of the supply roller 20. As a result, the supply roller 20 rotates while taking the toner supplied from the second opening 45 to the developing chamber 18b along the developing chamber bottom surface 26c below the supply roller 20.

  In deriving the evaluation result of Example 1, the angle β formed by the tangent line b of the developing chamber bottom surface 26c at the lower end 45b of the second opening 45 with the horizontal line a is 55 °. As described above, the repose angle of the non-magnetic single component toner is 30 °. Therefore, when there is no toner in the developing chamber 18b near the second opening 45, the toner inside the buffer chamber 18c collapses into the developing chamber 18b near the lower end 45b of the second opening 45. The toner moves from the buffer chamber 18c to the developing chamber 18b. For this reason, the height of the toner agent surface inside the developing chamber 18 b is always kept at the lower end 45 b or more of the second opening 45. Further, the height of the toner agent surface is maintained above the lower end of the supply roller 20. As a result, the contact area where the surface of the supply roller 20 comes into contact with the toner increases, and the efficiency of supplying the toner to the supply roller 20 is improved.

  The evaluation result of the developing unit 104 of the first comparative example will be described below. As shown in Table 1, the developing unit 104 of the first comparative example is good (◯) in terms of preventing the return of toner from the developing chamber 18b to the toner storage chamber 18a. Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is defective (x). In the developing unit 104 of the first comparative example, as shown in FIG. 4A, the opening valve 42 is in contact with the developing chamber bottom surface 26c, and the opening 50 is closed in a normal state. The opening valve 42 has elasticity. Further, the opening valve 42 is not in contact with the toner storage chamber conveyance member 22. The opening valve 42 is elastically deformed and the opening 50 is opened only when the toner is conveyed to the vicinity of the opening valve 42 by the toner storage chamber conveying member 22. The toner is transported from the toner storage chamber 18a to the developing chamber 18b by flying. Therefore, a large powder pressure is not applied to the opening valve 42 between the toner storage chamber 18a and the developing chamber 18b, and the opening valve 42 is elastically deformed only slightly. As a result, the opening 50 opens only slightly, and the return of toner from the developing chamber 18b to the toner storage chamber 18a is suppressed. However, since the opening 50 opens only slightly, the toner supply speed from the toner storage chamber 18a to the developing chamber 18b becomes insufficient.

  The evaluation result of the developing unit 204 of the second comparative example will be described below. As shown in Table 1, in the developing unit 204 of the second comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is defective (x). In the developing unit 204 of the second comparative example, as shown in FIG. 4B, the opening valve 42 is in contact with the developing chamber bottom surface 26c, and the opening 50 is closed in a normal state. The opening valve 42 has elasticity. The opening valve 42 includes an opening valve protrusion 42a on the surface of the toner storage chamber 18a. When the toner storage chamber conveyance member 22 rotates, the sheet portion 22a can come into contact with the opening valve protrusion 42a. At the time of contact, the opening valve 42 between the toner storage chamber 18a and the developing chamber 18b is elastically deformed to open the opening. 50 opens greatly. At this time, a large amount of toner returns from the developing chamber 18b to the toner storage chamber 18a. However, since the opening 50 is greatly opened, when there is no toner in the developing chamber 18b, the toner is supplied from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed.

  The evaluation result of the developing unit 304 of the third comparative example will be described below. As shown in Table 1, in the developing unit 304 of the third comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is almost good (Δ). In the developing unit 304 of the third comparative example, as shown in FIG. 5A, a first opening 44 is formed between the toner storage chamber 18a and the buffer chamber 18c, and between the buffer chamber 18c and the developing chamber 18b. A second opening 45 is formed in the. The lower end 44 a of the first opening 44 is set lower than the upper end 45 a of the second opening 45. With this configuration, the toner agent surface is connected from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. In this case, the toner near the toner agent surface can easily move from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. Further, the toner is transported from the toner storage chamber 18 a onto the toner agent surface of the toner existing inside the buffer chamber 18 c, and the height of the toner agent surface of the buffer chamber 18 c is set at the lower end of the first opening 44. It can only accumulate up to the same height as 44a. Therefore, the toner that cannot be stored in the buffer chamber 18c falls to the lower part of the toner storage chamber 18a. As a result, the toner inside the developing chamber 18b easily returns to the toner storage chamber 18a. However, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is almost satisfactory. Other principles are the same as in the first embodiment.

  The evaluation result of the developing unit 404 of the fourth comparative example will be described below. As shown in Table 1, in the developing unit 404 of the fourth comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. The toner supply from the toner storage chamber 18a to the developing chamber 18b is good (◯). In the developing unit 404 of the fourth comparative example, as shown in FIG. 5B, the first opening 44 is formed between the toner storage chamber 18a and the buffer chamber 18c, and the lower end 44a of the first opening 44 is the toner. It is lower than the conveyance support shaft 22 b which is the “rotation center” of the storage chamber conveyance member 22. In this case, the toner is transferred from the toner storage chamber 18a to the buffer chamber 18c so that a large powder pressure is applied to the buffer chamber 18c by the toner storage chamber transfer member 22. Further, the leading end of the sheet portion 22a of the toner storage chamber transport member 22 enters the buffer chamber 18c. Therefore, the toner is circulated and mixed in the buffer chamber 18c up and down, and further, the toner circulates in the buffer chamber 18c and the developing chamber 18b. In the developing unit 404 of the fourth comparative example, the lower end 44a of the first opening 44 is higher than the upper end 45a of the second opening 45, as shown in FIG. With this setting, the toner agent surface is not connected from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. That is, the toner inside the developing chamber 18b does not return to the toner storage chamber 18a unless it passes through the second opening 45 below the toner agent surface. However, as described above, the toner is mixed up and down inside the buffer chamber 18c, and the toner inside the buffer chamber 18c and the toner inside the developing chamber 18b circulate. Accordingly, the toner inside the developing chamber 18b returns to the toner storage chamber 18a. However, the toner is transferred from the toner storage chamber 18a to the buffer chamber 18c by the toner storage chamber transfer member 22 so that a large powder pressure is applied to the buffer chamber 18c. Therefore, the toner can be supplied to the developing chamber 18b at a sufficient speed, and the toner supply from the toner storage chamber 18a to the developing chamber 18b is good.

  The evaluation result of the developing unit 504 of the fifth comparative example will be described below. As shown in Table 1, in the developing unit 504 of the fifth comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is almost good (Δ). In the developing unit 504 of the fifth comparative example, as shown in FIG. 6A, a first opening 44 is formed between the toner storage chamber 18a and the buffer chamber 18c, and the lower end 44a of the first opening 44 is a toner. It is lower than the conveyance support shaft 22 b which is the “rotation center” of the storage chamber conveyance member 22. In this case, the toner is transferred from the toner storage chamber 18a to the buffer chamber 18c so that a large powder pressure is applied to the buffer chamber 18c by the toner storage chamber transfer member 22. Therefore, the toner is circulated up and down inside the buffer chamber 18c, the toner is mixed up and down, and the toner inside the buffer chamber 18c and the toner inside the developing chamber 18b circulate. In the developing unit 504 of the fifth comparative example, the lower end 44a of the first opening 44 is higher than the upper end 45a of the second opening 45, as shown in FIG. With this setting, the toner agent surface is not connected from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. That is, the toner inside the developing chamber 18b does not return to the toner storage chamber 18a unless it passes through the second opening 45 below the toner agent surface. However, as described above, the toner is mixed up and down inside the buffer chamber 18c, and the toner inside the buffer chamber 18c and the toner inside the developing chamber 18b circulate. Accordingly, the toner inside the developing chamber 18b returns to the toner storage chamber 18a. However, the toner is transferred from the toner storage chamber 18a to the buffer chamber 18c by the toner storage chamber transfer member 22 so that a large powder pressure is applied to the buffer chamber 18c. Therefore, the toner can be supplied to the developing chamber 18b at a sufficient speed, and the toner supply from the toner storage chamber 18a to the developing chamber 18b is almost satisfactory.

  The evaluation result of the developing unit 604 of the sixth comparative example will be described below. As shown in Table 1, in the developing unit 604 of the sixth comparative example, the toner return prevention from the developing chamber 18b to the toner storage chamber 18a is good (◯). Further, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is defective (x). The developing unit 604 of the sixth comparative example is similar in principle to the first embodiment as shown in FIG. 6B. However, as shown in FIG. 6B, at the lower end 45b of the second opening 45 between the buffer chamber 18c and the developing chamber 18b, the angle β ′ that the developing chamber bottom surface 26c forms with the horizontal line a is 15 °, The angle of repose is 30 °, and β ′ is smaller than the angle of repose of toner 30 °. Therefore, when there is no toner in the developing chamber 18b near the second opening 45, the toner in the buffer chamber 18c near the lower end 45b of the second opening 45 collapses from the buffer chamber 18c to the developing chamber 18b. The toner does not move from the buffer chamber 18c to the developing chamber 18b. As a result, toner is not supplied from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed.

  FIG. 7A is a cross-sectional view illustrating a configuration of the process cartridge 7 including the developing unit 74 according to the second embodiment. Among the configurations of the developing unit 74 of the second embodiment, the same configurations and effects as those of the developing unit 4 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate. Since the second embodiment can be applied to the same image forming apparatus as that of the first embodiment, the description of the image forming apparatus is omitted. The developing unit 74 of the second embodiment is different from the developing unit 4 of the first embodiment in that the developing unit 4 is not provided with a stirring member in the developing chamber 18b. The stirring member 31 which is a member is provided.

  As shown in FIG. 7A, the developing unit 74 includes a stirring member 31 inside the developing chamber 18b. That is, the stirring member 31 is rotatably supported by the developing frame 18 having the developing chamber 18b at both ends in the longitudinal direction (rotational axis direction). The stirring member 31 is rotationally driven in the direction of the arrow (clockwise) by a driving means (driving source) not shown. The stirring member 31 includes a rotatable rotating shaft 31b, and a sheet portion 31a that is attached to the rotating shaft 31b and has flexibility and stirs the toner. Further, the stirring member 31 is composed of “plurality”, that is, two sheet portions 31a having different shapes in the longitudinal direction. That is, as shown in FIG. 7A, one sheet portion 31a is provided upward from the rotating shaft 31b and one sheet below the rotating shaft 31b. The stirring member 31 rotates in a direction from the bottom to the top of the second opening 45 at a position before the second opening 45.

  The rotation shaft 31b is disposed substantially in parallel with the longitudinal direction (rotation axis direction) of the photosensitive drum 1, the developing roller 17, and the supply roller 20 and over the entire region in the longitudinal direction of the developing chamber 18b. The sheet portion 31a is a continuous sheet (plate-like member) extending over substantially the entire region in the longitudinal direction (rotation axis direction) of the rotation shaft 31b. And the sheet | seat part 31a is attached to the rotating shaft 31b in the one end part of the direction (rotating radial direction, a transversal direction) substantially orthogonal to the longitudinal direction of the rotating shaft 31b.

  One sheet portion 31a, that is, a total of two sheets, is attached to two surfaces of the rotating shaft 31b having different phases by 180 °. Moreover, the shape of the rotating shaft 31b is not limited to a quadrangular section, and may be, for example, a cylindrical section or a polygonal section. Further, the number of sheet portions 31a is not limited to two, and may be any number as long as it is one or more. The agitating member 31 is designed so that the sheet portion 31a comes into contact with the developing chamber bottom surface 26b, but is not greatly elastically deformed. However, the sheet portion 31a may not be in contact with the developing chamber bottom surface 26b. In addition, the stirring member 31 uses only the inside of the developing chamber 18b as a stirring region, and at the same time, sets the outside of the buffer chamber 18c as a rotating region.

  The sheet portion 31a can be suitably manufactured using a flexible resin sheet such as a polyester film, a polyphenylene sulfide film, or a polycarbonate film. The thickness of the sheet portion 31a is preferably 50 μm to 250 μm. The one-component developer used in Example 2 is the same as the one-component developer used in Example 1. In addition, the toner conveyance configuration from the toner storage chamber 18a to the buffer chamber 18c is the same as that of the first embodiment.

[Configuration of toner supply from buffer chamber 18c to developing chamber 18b]
Next, the toner supply configuration from the buffer chamber 18c to the developing chamber 18b in the developing unit 204 of Embodiment 2 will be described in detail. In the second embodiment, the partition wall 26 includes a developing chamber bottom surface 26 b formed in a concave shape below the stirring member 31, and a developing chamber bottom surface 26 a formed in a concave shape below the supply roller 20. The partition wall 26 includes a buffer chamber bottom surface 26d located below the buffer chamber 18c, and a partition wall 26e that partitions the toner storage chamber 18a and the buffer chamber 18c.

  FIG. 7B is an enlarged cross-sectional view showing the configuration of the developing unit 74. As shown in FIG. 7B, a partition wall 43 and a second opening 45 are formed between the buffer chamber 18c and the developing chamber 18b. The lowermost part of the partition wall 43 corresponds to the upper end 45 a of the second opening 45. Here, a vertical line passing through the boundary point between the buffer chamber bottom surface 26 d and the developing chamber bottom surface 26 b and the lower end portion of the partition wall 43 is assumed. The lower end portion of the partition wall 43 is defined as the upper end 45a of the second opening 45, and the boundary point between the buffer chamber bottom surface 26d and the developing chamber bottom surface 26b is defined as the lower end 45b of the second opening 45. The stirring member 31 rotates so that the surface moves from the bottom to the top at a position facing the second opening 45. Further, the lower end 45b of the second opening 45 is disposed above the lowest lowest position of the developing chamber bottom surface 26b. Further, the angle δ formed by the tangent line b of the developing chamber bottom surface 26b at the lower end 45b of the second opening 45 with the horizontal line a is 60 °. The angle of repose of the non-magnetic one-component toner used in Example 2 is 30 °.

  When there is sufficient toner in the developing chamber 18b near the second opening 45, the toner does not move from the buffer chamber 18c to the developing chamber 18b. However, when there is no toner in the developing chamber 18b in the vicinity of the second opening 45, the toner in the buffer chamber 18c near the lower end 45b of the second opening 45 is transferred from the buffer chamber 18c to the developing chamber 18b. Since the toner falls, the toner moves from the buffer chamber 18c to the developing chamber 18b. In particular, the rotation of the stirring member 31 causes the buffer chamber 18c to collapse into the developing chamber 18b. The toner near the second opening 45 can be quickly supplied to the supply roller 20. Further, the height of the toner agent surface inside the developing chamber 18 b can always be kept at the lower end 45 b or more of the second opening 45. Therefore, the toner accumulated near the developing chamber bottom surface 26 b below the stirring member 31 can be always supplied to the supply roller 20 by the stirring member 31.

[Method for preventing toner return from developing chamber 18b to toner storage chamber 18a]
The sheet portion 31a of the stirring member 31 is set so as to be in contact with the developing chamber bottom surface 26b but not to be greatly elastically deformed. Even if the stirring member 31 rotates, the force for pushing the toner out of the rotation radius of the stirring member 31 is weak. That is, the force for pushing the toner from the developing chamber 18b to the buffer chamber 18c is weak, and a large powder pressure is not applied from the developing chamber 18b to the buffer chamber 18c. Further, as shown in FIG. 7B, the rotation radius of the stirring member 31 is approximately the same as the radius of the supply roller 20. The amount of toner that can be stirred by the stirring member 31 is about the same as the amount of toner in the rotation region of the stirring member 31. Accordingly, the amount of toner that can be pushed out from the developing chamber 18b to the buffer chamber 18c is small, and a large powder pressure is not applied from the developing chamber 18b to the buffer chamber 18c.

  Further, the stirring region of the stirring member 31 is only inside the developing chamber 18b and outside the buffer chamber 18c. Therefore, the toner inside the buffer chamber 18 c is not circulated up and down by the stirring member 31.

  The toner in the buffer chamber 18c is slightly vibrated by the influence of the rotation of the stirring member 31 and does not form a non-moving layer. Therefore, when there is no toner inside the developing chamber 18b near the second opening 45, the toner inside the buffer chamber 18c near the lower end 45b of the second opening 45 easily moves from the buffer chamber 18c to the developing chamber 18b. Therefore, the toner moves from the buffer chamber 18c to the developing chamber 18b.

  Further, since the toner inside the buffer chamber 18c is minutely vibrated by the rotation of the stirring member 31, it is not clogged and does not hinder the toner supply from the toner storage chamber 18a to the developing chamber 18b.

(Seventh comparative example)
FIG. 8 is an enlarged cross-sectional view showing the configuration of the developing unit 704 of the seventh comparative example. In the developing unit 704 of the second embodiment, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b is immovable, but is movable in the seventh comparative example. That is, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b has elasticity. In Example 2, the stirring region of the stirring member 31 is only inside the developing chamber 18b and outside the buffer chamber 18c. On the other hand, in the seventh comparative example, the sheet portion 31a of the stirring member 31 is made longer than that in Example 2, and the stirring region of the stirring member 31 is set to enter the buffer chamber 18c. Furthermore, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b comes into contact with the stirring member 31, and is elastically deformed when in contact.

(Eighth comparative example)
The configuration of the developing unit of the eighth comparative example is substantially the same as the developing unit 704 of the seventh comparative example. However, the developing unit of the eighth comparative example is different from the developing unit 704 of the seventh comparative example that the partition wall 43 does not move and the developing unit 704 of the seventh comparative example is movable as in the developing unit 74 of the second embodiment. In Example 2, the stirring region of the stirring member 31 was only inside the developing chamber 18b and outside the buffer chamber 18c. On the other hand, in the eighth comparative example, the sheet portion 31a of the stirring member 31 is made longer than that in Example 2, and the stirring region of the stirring member 31 is set to enter the buffer chamber 18c. In Example 2, the seventh comparative example, and the eighth comparative example, a method for evaluating the return of toner from the developing chamber 18b to the toner storage chamber 18a, and the supply of toner from the toner storage chamber 18a to the developing chamber 18b. The same method as in Example 1 was used as a method for evaluating the above.

[Evaluation results of Example 2 and seventh comparative examples to 8]
Table 2 is a table showing the evaluation results applied to Example 2, the seventh comparative example, and 8.

表２に示されるように、実施例２の現像ユニット７４では、現像室１８ｂからトナー収納室１８ａへのトナーの戻り防止に関しては良好（○）である。また、トナー収納室１８ａから現像室１８ｂへのトナーの供給に関しては良好（○）である。

As shown in Table 2, in the developing unit 74 of Example 2, the prevention of the return of toner from the developing chamber 18b to the toner storage chamber 18a is good (◯). The toner supply from the toner storage chamber 18a to the developing chamber 18b is good (◯).

  In particular, the presence of the stirring member 31 of the second embodiment makes it possible to supply the toner from the toner storage chamber 18a to the developing chamber 18b with the following actions. The principle will be described with reference to FIG. The lower end 45b of the second opening 45 is disposed above the lowest lowest position of the developing chamber bottom surface 26b. The angle δ formed by the tangent line b of the developing chamber bottom surface 26b at the lower end 45b of the second opening 45 with the horizontal line a is 60 °. The angle of repose of the non-magnetic one-component toner used in Example 2 is 30 °.

  Accordingly, when there is sufficient toner in the developing chamber 18b near the second opening 45, the toner does not move from the buffer chamber 18c to the developing chamber 18b. However, when there is no toner inside the developing chamber 18b near the second opening 45, the toner inside the buffer chamber 18c near the lower end 45b of the second opening 45 collapses from the buffer chamber 18c to the developing chamber 18b. Therefore, the toner moves from the buffer chamber 18c to the developing chamber 18b. In particular, the toner in the vicinity of the second opening 45, which has collapsed from the buffer chamber 18c to the developing chamber 18b as the stirring member 31 rotates, can be quickly supplied to the supply roller 20. When the developing unit 74 of Embodiment 2 is used, toner is supplied from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed. Further, the height of the toner agent surface inside the developing chamber 18b can always be maintained at the lower end 45b or more of the second opening 45 between the buffer chamber 18c and the developing chamber 18b. Therefore, the toner accumulated near the developing chamber bottom surface 26 b is always supplied to the supply roller 20 by the stirring member 31.

  The evaluation result of the developing unit 704 of the seventh comparative example will be described below. As shown in Table 2, in the developing unit 704 of the seventh comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. The toner supply from the toner storage chamber 18a to the developing chamber 18b is good (◯).

  In the second embodiment, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b is immovable, but in the seventh comparative example, it is movable. That is, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b has elasticity. In Example 2, the stirring region of the stirring member 31 was only inside the developing chamber 18b and outside the buffer chamber 18c. On the other hand, in the seventh comparative example, the sheet portion 31a of the stirring member 31 is made longer than that in the second embodiment so that the stirring region of the stirring member 31 enters the buffer chamber 18c. Furthermore, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b comes into contact with the stirring member 31, and is elastically deformed when in contact.

  When the partition wall 43 between the buffer chamber 18c and the developing chamber 18b is elastically deformed, the toner inside the buffer chamber 18c is agitated, and the toner is mixed up and down inside the buffer chamber 18c. At the same time, the movement of the toner inside the buffer chamber 18c becomes intense and mixes with the toner inside the developing chamber 18b. In particular, when the stirring region of the stirring member 31 is set so as to enter the buffer chamber 18c, the movement of the toner inside the buffer chamber 18c becomes intense and mixes up and down inside the buffer chamber 18c. Further, the internal toner in the buffer chamber 18c and the internal toner in the developing chamber 18b are likely to be mixed. Accordingly, the toner inside the developing chamber 18b returns to the toner storage chamber 18a.

  However, in the seventh comparative example, the toner supply from the toner storage chamber 18a to the developing chamber 18b is good. The principle is the same as in the second embodiment.

  The evaluation result of the developing unit of the eighth comparative example will be described below. As shown in Table 2, in the developing unit of the eighth comparative example, it is impossible (×) to prevent the toner from returning from the developing chamber 18b to the toner storage chamber 18a. The toner supply from the toner storage chamber 18a to the developing chamber 18b is good (◯).

  In the seventh comparative example, the partition wall 43 between the buffer chamber 18c and the developing chamber 18b is movable, but in the eighth comparative example, it is immovable. In Example 2, the stirring region of the stirring member 31 was only inside the developing chamber 18b and outside the buffer chamber 18c. On the other hand, in the eighth comparative example, the sheet portion 31a of the stirring member 31 is made longer than that in Example 2, and the stirring region of the stirring member 31 is set to enter the buffer chamber 18c.

  When the stirring region of the stirring member 31 is set so as to enter the buffer chamber 18c, the movement of the toner inside the buffer chamber 18c becomes intense, and the toner inside the buffer chamber 18c is moved up and down, and the toner inside the buffer chamber 18c. The toner inside the developing chamber 18b is likely to be mixed. Accordingly, the toner inside the developing chamber 18b returns to the toner storage chamber 18a. However, in the eighth comparative example, the toner supply from the toner storage chamber 18a to the developing chamber 18b is good. The principle is the same as in the second embodiment.

  FIG. 9A is a cross-sectional view illustrating a configuration of the developing unit 84 according to the third embodiment. Among the configurations of the developing unit 84 of the third embodiment, the same reference numerals are used for the same configurations and effects as those of the developing unit 4 of the first embodiment and the developing unit 74 of the second embodiment, and description thereof is omitted as appropriate. Since the third embodiment can be applied to the same process cartridge and image forming apparatus as those in the first embodiment, the description of the process cartridge and the image forming apparatus is omitted. The development unit 84 of the third embodiment is different from the development unit 4 of the first embodiment in the following points. In the developing chamber 18b in the second embodiment, a stirring chamber 18d which is a “fourth chamber” is partitioned by a partition wall 48 which is a “partition wall” having a third opening 46 which is a “third opening”. Is formed. For this purpose, the developing frame 18 is composed of a toner storage chamber 18a as a “first chamber”, a buffer chamber 18c as a “second chamber”, an agitation chamber 18d as a “fourth chamber”, and a “third chamber”. A developing chamber 18b. The toner storage chamber 18 a and the buffer chamber 18 c are connected via the first opening 44. The buffer chamber 18c and the stirring chamber 18d are connected via a fourth opening 49 which is a “fourth opening”. Further, the stirring chamber 18 d and the developing chamber 18 b are connected via the third opening 46.

  The developing frame 18 includes a developing chamber bottom surface 26a, a stirring chamber bottom surface 26g, a buffer chamber bottom surface 26d, and a partition wall 26e. The developing chamber bottom surface 26 a is a wall surface that separates the developing chamber 18 b and the toner storage chamber 18 a and is located below the supply roller 20. The stirring chamber bottom surface 26g is a wall surface separating the stirring chamber 18d and the toner storage chamber 18a, and is located below the stirring member 31. The buffer chamber bottom surface 26d is a wall surface separating the buffer chamber 18c and the toner storage chamber 18a, and corresponds to the floor surface of the buffer chamber 18c. The partition wall 26e is a wall that separates the interior of the toner storage chamber 18a.

  The stirring member 31 of Example 3 shown in FIG. 9A is the same as the stirring member of Example 2 in terms of configuration and operation. The one-component developer used in Example 3 is the same as the one-component developer used in Example 1. The toner conveyance configuration from the toner storage chamber 18a to the buffer chamber 18c in the third embodiment is the same as the toner conveyance configuration in the first embodiment. The toner supply configuration from the buffer chamber 18c to the stirring chamber 18d in the third embodiment is the same as the toner supply configuration from the buffer chamber 18c to the developing chamber 18b in the second embodiment. The toner return prevention method from the stirring chamber 18d to the toner storage chamber 18a in the third embodiment is the same as the toner return prevention method from the developing chamber 18b to the toner storage chamber 18a in the second embodiment.

  A toner supply configuration from the stirring chamber 18d to the developing chamber 18b will be described below. A partition wall 48 is formed between the stirring chamber 18d and the developing chamber 18b, and a third opening 46 is formed. The lowermost part of the partition wall 48 corresponds to the upper end 46 a of the third opening 46. The intersection where the vertical line passing through the upper end 46 a of the third opening 46 intersects the developing chamber bottom surface 26 a corresponds to the lower end 46 b of the third opening 46. Therefore, the lower end 46b of the third opening 46 is a boundary between the developing chamber bottom surface 26a and the stirring chamber bottom surface 26g.

  The supply roller 20 rotates in a direction in which the surface facing the third opening 46 moves from top to bottom. That is, the supply roller 20 rotates so as to take in the toner supplied from the third opening 46 to the developing chamber 18b downward along the developing chamber bottom surface 26a. The lower end 46b of the third opening 46 is disposed above the lowest position of the stirring chamber bottom surface 26g.

  When there is sufficient toner in the developing chamber 18b near the third opening 46, the toner does not move from the stirring chamber 18d to the developing chamber 18b. However, when there is not enough toner in the developing chamber 18b in the vicinity of the third opening 46, the toner in the stirring chamber 18d in the vicinity of the lower end 46b of the third opening 46 is mixed by the stirring member 31 with the stirring chamber 18d. To the developing chamber 18b. The toner in the vicinity of the third opening 46 is stirred by the stirring member 31 and the stirring member 25 (described later), and the toner in the stirring chamber 18d and the toner in the developing chamber 18b are easily mixed. As in the second embodiment, new toner is replenished from the toner storage chamber 18a only when the toner in the stirring chamber 18d is reduced. A large amount of deteriorated toner stays in the developing chamber 18b for a long time in the stirring chamber 18d. However, the stirring toner 31 causes the toner in the stirring chamber 18d and new toner replenished from the toner storage chamber 18a. Is mixed with stirring so as to mix uniformly.

  In general, new toner and deteriorated toner have different chargeability and fluidity. If the new toner and the deteriorated toner are not sufficiently mixed, a problem may occur immediately after the new toner is replenished. In other words, “fogging” on the white background of the image caused by electrostatic aggregation of new toner and deteriorated toner, or “density” in which there is a difference in image density between a portion with a lot of new toner and a portion with a small amount in one image. Image defects such as “unevenness” may occur. Therefore, in the stirring chamber 18d, after the new toner and the deteriorated toner are sufficiently mixed using the stirring member 31, the toner is supplied to the developing chamber 18b, whereby the above-described image defect can be prevented.

[Developing chamber 18b stirring configuration]
Next, with reference to FIGS. 9A to 10B, the stirring of the toner inside the developing unit 84 will be described. FIG. 9A to FIG. 10B are cross-sectional views illustrating the configuration of the developing unit 84 according to the third embodiment. A stirring member 31 that is a “fourth chamber stirring member” is disposed inside the stirring chamber 18d. A stirring member 25 that is a “third chamber stirring member” is disposed in the developing chamber 18b in a region adjacent to the stirring chamber 18d in order to flow and circulate the toner inside the developing chamber 18b. The developing chamber 18 b is disposed in the vicinity of a developing roller 17 that can rotate while carrying a one-component developer, and a supply roller 20 that can supply the one-component developer to the developing roller 17.

  Thereby, it is possible to suppress toner packing, that is, toner clogging more densely than necessary, and supply toner to the developing roller 17 and stabilization of toner regulation on the developing roller 17 can be achieved. The image can be improved by promoting the circulation of the toner around the developing roller 17 and the supply roller 20, suppressing the toner packing, and stably supplying the toner to the developing roller 17. On the other hand, when the toner supply to the developing roller 17 becomes unstable, image defects such as image unevenness may occur. Accordingly, one of the purposes of the third embodiment is to satisfactorily circulate the toner around the developing roller 17 and the like, thereby suppressing image defects such as image unevenness due to poor toner supply.

  In the third embodiment, the developing unit 84 is configured as follows. In the developing unit 84 of the third embodiment, the stirring member 25 is disposed inside the developing chamber 18b. As shown in FIG. 9A, the stirring member 25 includes a stirring support shaft 25b that is a “rotation center” that is rotatably supported by the developing chamber 18b, and a rotation of the stirring support shaft 25b that is fixed to the stirring support shaft 25b. And a stirring unit 25a that swings in conjunction with the toner and stirs the toner inside the developing chamber 18b. The stirring support shaft 25b is positioned downstream of the stirring unit 25a in the rotation direction of the supply roller 20. Thereby, the movement of the stirring unit 25a can be increased on the downstream side of the supply roller 20 in the rotation direction. The stirring unit 25 a is located between the supply roller 20 and the partition wall 26.

  FIG. 11 is a front view showing the configuration of the stirring member 25. As shown in FIG. 11, the stirring portion 25a is provided with a stirring opening 25c for allowing the toner to pass therethrough. When the stirring unit 25a swings as described above, the operation in which the stirring opening 25c approaches the supply roller 20 and the operation in which the stirring opening 25c moves away from the supply roller 20 are repeated. In the operation in which the stirring opening 25 c approaches the supply roller 20, the peripheral edge of the stirring opening 25 c moves the toner toward the supply roller 20. In the operation in which the stirring opening 25c moves away from the supply roller 20, the toner existing below the stirring opening 25c moves toward the supply roller 20 through the stirring opening 25c. As described above, the stirring portion 25a swings and the stirring opening portion 25c moves, so that the toner is satisfactorily supplied to the supply roller 20 while being sufficiently stirred. The agitating unit 25 a advances and retreats along the tangential direction of the supply roller 20. That is, the stirring unit 25a swings along the tangential direction of the circle (rotation locus) of the rotation radius of the supply roller 20. In other words, the stirring unit 25a also swings along the rotation direction of the supply roller 20 (direction intersecting the rotation axis). This movement of the stirring unit 25a can further stir the toner. When the toner is consumed, the toner conveyed to the developing chamber 18b is stored in a region between the supply roller 20 and the developing chamber bottom surface 26a. The supply roller 20 supplies the toner stored in the area below the supply roller to the developing roller 17.

  Further, as shown in FIG. 9A, the agitation unit 25 a described above is disposed in a region below the supply roller 20. The agitator 25a is formed in a substantially “<L” shape when the developing roller 17 and the supply roller 20 are viewed in cross section. In addition, as illustrated in FIG. 11, the stirring unit 25a includes a first surface 25g and a second surface 25h in order from the stirring support shaft 25b side. The first surface 25g and the second surface 25h are connected to each other, and a bent portion 25f that is bent is formed. The first surface 25g is a surface that extends along the direction of the stirring support shaft 25b. Further, the second surface 25h is disposed at a predetermined angle with respect to the first surface 25g, and is similarly a surface extending along the direction of the stirring support shaft 25b. The first surface 25g and the second surface 25h intersect each other. As shown in FIG. 9A, the stirring unit 25 a is bent in a protruding shape toward the normal direction of the supply roller 20. That is, the recess formed by the first surface 25 g and the second surface 25 h faces the supply roller 20. In addition, this stirring part 25a is shape | molded with resin. However, the stirring part 25a may be shape | molded, for example with the metal.

  The agitation support shaft 25b described above is rotatably disposed in a region below the supply roller 20. And the stirring part 25a is rotatably supported by the stirring support shaft 25b. The agitation support shaft 25b is disposed over the entire area in the longitudinal direction of the developing chamber 18b substantially parallel to the longitudinal direction of the developing roller 17 and the supply roller 20. The agitation support shaft 25b is rotatably supported by the developing device frame 18 forming the developing chamber 18b at both ends in the longitudinal direction (rotational axis direction).

  As shown in FIG. 11, an engaging end 25a1 that engages with the stirring support shaft 25b is formed at one edge of the stirring portion 25a. The stirring portion 25a is engaged (coupled) with the stirring support shaft 25b so as to be able to rotate (turn). The stirring support shaft 25b of the stirring member 25 is a shaft to which a stirring portion 25a that is a “stirring member” is coupled at an eccentric position with respect to the rotation center thereof. Then, as shown in FIGS. 9A to 10B, the stirring support shaft 25b is rotationally driven by a driving means (drive source) not shown to engage with the stirring support shaft 25b of the stirring portion 25a. The free end 25a2, which is one end of the non-moving end, reciprocates. That is, the stirring unit 25 a reciprocates along the tangential direction of the supply roller 20. The free end 25a2 of the stirring unit 25a moves in a direction approaching the third opening 46 or in a direction away from the third opening 46 at a position between the developing chamber bottom surface 26a and the supply roller 20 according to a reciprocal movement locus. To do. Then, the agitating unit 25a comes into contact with the toner stored therein. As described above, the agitating unit 25a reciprocates between the supply roller 20 and the developing chamber bottom surface 26a. As a result, it is possible to prevent the toner supplied to the developing chamber 18b from being packed in a narrow region of the supply roller 20 and the developing chamber bottom surface 26a, thereby reducing fluidity. Supply can be promoted.

  In the third embodiment, the stirring unit 25a enters the narrow area between the supply roller 20 and the developing chamber bottom surface 26a. However, the present invention is not limited to this configuration. That is, if the reciprocating motion of the free end 25a2 of the stirring unit 25a can promote the circulation of toner in the developing chamber 18b and suppress the toner packing and the like, the free end 25a2 of the stirring unit 25a is not necessarily provided with the supply roller 20 and the developing chamber. It is not necessary to enter a narrow area between the bottom surfaces 26a.

  Simultaneously with the above-described reciprocating motion, the agitating portion 25 a swings in the direction of contacting and separating from the supply roller 20 along the radial direction of the supply roller 20. As a result, the agitating unit 25 a acts to agitate the toner stored in the region below the supply roller 20 to suppress packing and the like and to press against the supply roller 20. Here, the movement of the stirring unit 25a will be described with reference to FIGS. 9 (a) to 10 (b).

  As shown in FIG. 9A, the second surface 25h (see FIG. 11), which is the “free end side portion” corresponding to the free end 25a2 side portion of the stirring portion 25a, enters the bottom of the toner. Then, the toner is pressed against the supply roller 20. Next, as shown in FIG. 9B, the first surface 25g (see FIG. 11) which is an “engagement end side portion” corresponding to the engagement end 25a1 side portion of the stirring portion 25a is the toner. Is pressed against the supply roller 20. Next, as shown in FIG. 10A, the first surface 25g and the second surface 25h are retracted. At this time, the toner below the stirring unit 25a moves to the surface of the stirring unit 25a through the stirring opening 25c and moves to the supply roller 20. Next, as shown in FIG. 10B, the second surface 25 h again presses the toner against the supply roller 20. In other words, the toner is pressed against the supply roller 20 at different places in the rotation direction of the supply roller 20 in the stirring unit 25a. Thus, when the stirring unit 25a swings, the supply of toner by the supply roller 20 is promoted.

  Regardless of the rotation direction of the agitation support shaft 25b, the effect of suppressing the packing of toner in a narrow region between the supply roller 20 and the developing chamber bottom surface 26a, and the toner supply to the supply roller 20 are promoted. An effect is obtained. The stirring support shaft 25b is rotationally driven in a clockwise direction by a driving unit (drive source) (not shown) to swing (reciprocate) the stirring unit 25a.

  As shown in FIG. 11, the stirring unit 25 a has a plate shape, and the stirring unit 25 a has a stirring opening 25 c formed on the surface facing the supply roller 20. The stirring portion 25a is provided with a stirring opening 25c. The stirring opening 25c includes a plurality of openings (through holes) 25c1, 25c2, and 25c3. Therefore, the stirring unit 25a swings so as to have a step in which the stirring opening 25c approaches the supply roller 20 and a step in which the stirring opening 25c moves away from the supply roller 20. In other words, by providing the stirring opening 25c, the toner can be released from the stirring opening 25c without pushing the toner below the stirring part 25a by the reciprocating motion of the stirring part 25a. Thereby, the fluidity of the toner can be ensured, and the toner supply to the supply roller 20 can be promoted.

  Here, in the rotation direction of the supply roller 20, the opening located in the downstream row is referred to as a first stirring opening 25c1, and the opening disposed upstream of the first stirring opening 25c1 is referred to as a second stirring opening 25c2. And when the 1st stirring opening 25c1 and the 2nd stirring opening 25c2 are projected on the rotating shaft of the supply roller 20, a part of 1st stirring opening 25c1 has overlapped with a part of 2nd stirring opening 25c2. As a result, toner agitation unevenness in the longitudinal direction of the supply roller 20 can be reduced. Furthermore, the opening aligned with the first stirring opening 25c1 in the direction parallel to the rotation axis of the stirring support shaft 25b is defined as a third stirring opening 25c3. When the region R between the first stirring opening 25c1 and the third stirring opening 25c3 and the second stirring opening 25c2 are projected onto the rotation shaft of the supply roller 20, the region R is a part of the second stirring opening 25c2. It overlaps with the department. As a result, it is possible to prevent image unevenness from occurring in the region R.

  Here, the second stirring opening 25c2 is provided in the second surface 25h, and the first stirring opening 25c1 and the third stirring opening 25c3 are provided in the first surface 25g, but each opening is different. It may be provided on a flat surface. That is, the second stirring opening 25c2 may be provided in the first surface 25g, and the first stirring opening 25c1 and the third stirring opening 25c3 may be provided in the second surface 25h.

  According to the present embodiment, the free end side of the agitating unit 25a enters a region where the distance between the supply roller 20 and the developing chamber bottom surface 26a is narrow and reciprocates, so that the space between the supplying roller 20 and the developing chamber bottom surface 26a is between. A narrow area of toner is agitated. As a result, it is possible to prevent the toner from being packed in a narrow region between the supply roller 20 and the developing chamber bottom surface 26a and the fluidity from being lowered.

  According to the present embodiment, toner supply to the region below the supply roller 20 and the supply roller 20 can be promoted. Therefore, the toner supply from the supply roller 20 to the developing roller 17 is stabilized, and it is possible to suppress the occurrence of image defects such as image unevenness due to a defective toner supply.

  FIG. 12 is a cross-sectional view illustrating a configuration of the developing unit 94 according to the fourth embodiment. Among the configurations of the developing unit 94 of the fourth embodiment, the same reference numerals are used for the same configurations and effects as those of the developing unit 4 of the first embodiment, the developing unit 74 of the second embodiment, and the developing unit 94 of the third embodiment. Description is omitted as appropriate. Since the fourth embodiment can be applied to the same process cartridge and image forming apparatus as those in the first to third embodiments, the description of the process cartridge and the image forming apparatus is omitted. The development unit 94 of the fourth embodiment is different from the development units 4, 74, and 84 of the first to third embodiments in the following points. That is, in Examples 2 and 3, one stirring member is provided inside the developing chamber 18b, but in Example 4, two stirring members are provided inside the developing chamber 18b. The operation of the image forming apparatus is the same as in the first to third embodiments. Here, two stirring members are provided, but two or more stirring members may be provided.

  The stirring member 31 of Example 4 has the same configuration and operation as the stirring member 31 of Example 2. The one-component developer used in Example 4 is the same as the one-component developer used in Example 1. The toner transport configuration from the toner storage chamber 18a to the buffer chamber 18c in the fourth embodiment is the same as that in the first embodiment. The toner supply configuration from the buffer chamber 18c to the developing chamber 18b in the fourth embodiment is the same as that in the second embodiment. The toner return prevention method from the developing chamber 18b to the toner storage chamber 18a of the fourth embodiment is the same as that of the second embodiment. The stirring member 25 of Example 4 has the same configuration and effect as the stirring member 25 of Example 3.

[Other Examples]
As mentioned above, although the specific Example of this invention was described, this invention is not limited to the above-mentioned Example, The following Example may be sufficient.

[Continuity of tilt angle between bottom of development chamber and bottom of buffer chamber]
FIG. 13 is a cross-sectional view showing a configuration of a modified example of the developing unit. As shown in FIG. 13, a lower end 45b of the second opening 45 between the buffer chamber 18c and the developing chamber 18b serves as a boundary between the developing chamber bottom surface 26c and the buffer chamber bottom surface 26d. In the vicinity of the lower end 45b of the second opening 45 between the buffer chamber 18c and the developing chamber 18b, in Examples 1 to 4, the inclination angle of the developing chamber bottom surface 26c and the inclination angle of the buffer chamber bottom surface 26d are set to be different. However, it is not limited to this configuration. For example, as shown in FIG. 13, in the vicinity of the lower end 45b of the second opening 45, the inclination angle of the developing chamber bottom surface 26c and the inclination angle of the buffer chamber bottom surface 26d may coincide. In the developing unit 95 of FIG. 13, at the lower end 45b of the second opening 45, the angle β formed by the tangent line b of the developing chamber bottom surface 26c and the horizontal line a is 40 °. Even in such a case, similarly to the first embodiment, it is possible to reduce the return of toner from the developing chamber 18b to the toner storage chamber 18a and to replenish the toner from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed. Can be realized at the same time.

[Relationship between lower end of opening between buffer chamber 18c and developing chamber 18b, and bottom of developing chamber bottom]
FIG. 14A is a partially enlarged cross-sectional view showing a configuration of a modified example of the developing unit. FIG. 14A shows the arrangement relationship between the lower end 45b of the second opening 45 and the lowest lowest position 26b1 of the developing chamber bottom surface 26a. A line connecting the lower end 45b of the second opening 45 and the lowest lowest position 26b1 of the developing chamber bottom surface 26a of the developing chamber 18b is defined as a virtual straight line c. An angle ξ formed by the virtual straight line c with the horizontal line a is 40 °. If there is no toner in the developing chamber 18b near the second opening 45, the toner inside the buffer chamber 18c near the lower end 45b of the second opening 45 collapses from the buffer chamber 18c to the developing chamber 18b. The toner moves from the buffer chamber 18c to the developing chamber 18b. Thus, if the angle ξ formed by the imaginary straight line c connecting the lower end 45b of the second opening 45 and the lowest position 26b1 of the developing chamber bottom surface 26a with the horizontal line a is equal to or greater than the toner repose angle, the toner storage chamber 18a to the developing chamber 18b Therefore, it is possible to supply the toner at a sufficient speed.

[Development chamber bottom shape]
In Example 2, as shown in FIG. 7C, the bottom surface continuous from the lower end 45b of the second opening 45 to the lowest lowest position 26b1 of the developing chamber bottom surface 26c of the developing chamber 18b is the first region R1 and the first region R1. It can be divided into two regions R2. Here, the first region R1 is disposed on the side close to the lower end 45b of the second opening 45, and is formed with an inclination angle larger than the repose angle of the one-component developer. The second region R2 is disposed on the side farther from the lower end 45b of the second opening 45, and has an inclination angle smaller than the repose angle of the one-component developer. As shown in FIG. 7C, between the lower end 45b of the second opening 45 and the lowest position 26b1 of the developing chamber bottom surface 26b, the inclination angle of the developing chamber bottom surface 26b is changed from a region larger than the repose angle of the toner to a smaller region. It has changed. In the region where the inclination angle of the developing chamber bottom surface 26b is larger than the repose angle of the toner, the toner can be moved toward the lowest position 26b1 on the developing chamber bottom surface. Further, toner can be accumulated in a region where the inclination angle of the developing chamber bottom surface 26b is smaller than the repose angle of the toner near the lowest position 26b1 on the developing chamber bottom surface. As described above, when the inclination angle of the developing chamber bottom surface 26b changes from the region larger than the repose angle of the toner to the small region between the lower end 45b of the second opening 45 and the lowest position 26b1 on the developing chamber bottom surface, Replenishment of toner is realized at a sufficient speed from 18a to developing chamber 18b.

[Relationship Between Lower End 44a of Opening 44 and Upper End 45a of Opening 45]
In the developing units of Embodiments 1 to 4, the lower end 44 a of the first opening 44 is set higher than the upper end 45 a of the second opening 45. With this setting, the toner agent surface is not connected from the vicinity of the supply roller 20 to the lower end 44 a of the first opening 44. That is, the toner inside the developing chamber 18b does not return to the toner storage chamber 18a unless it passes through the second opening 45 below the toner agent surface. Therefore, the toner inside the developing chamber 18b is difficult to return to the toner storage chamber 18a. In addition to the above conditions, if the following condition is further satisfied, the toner agent surface can be more reliably prevented from being connected from the vicinity of the supply roller 20 to the lower end 44a of the first opening 44.

  FIG. 14B is a cross-sectional view showing the positional relationship between the lower end 44 a of the first opening 44 and the upper end 45 a of the second opening 45. Here, the angle formed by the imaginary straight line d connecting the lower end 44a of the first opening 44 and the upper end 45a of the second opening 45 with the horizontal line a is set larger than the repose angle of the one-component developer. For example, when a line connecting the lower end 44a of the first opening 44 and the upper end 45a of the second opening 45 is a virtual straight line d, the angle α that the virtual straight line d forms with the horizontal line a is set to 40 °. Suppose. The repose angle of the non-magnetic one-component toner used here is 30 °. Therefore, even if toner collapse is considered, it is possible to more reliably prevent the toner agent surface from being connected from the vicinity of the supply roller 20 to the lower end 44a of the first opening 44. As described above, if the angle α formed by the imaginary straight line d connecting the lower end 44a of the first opening 44 and the upper end 45a of the second opening 45 with the horizontal line a is equal to or larger than the toner repose angle, the developer chamber 18b is more reliably removed. The return of toner to the toner storage chamber 18a can be reduced.

[Relationship between toner storage chamber conveying member and buffer chamber 18c]
In the developing units of Embodiments 1 to 4, the toner storage chamber conveyance member 22 is configured not to enter the buffer chamber 18c. The lower end 44 a of the first opening 44 is set higher than the rotation center of the toner storage chamber transport member 22. Therefore, since the toner is transported from the toner storage chamber 18a by flying the toner, a large powder pressure is not applied to the toner in the buffer chamber 18c. That is, the toner in the toner storage chamber 18a and the toner in the buffer chamber 18c are mixed only in the vicinity of the toner agent surface of the buffer chamber 18c, and the toner in the buffer chamber 18c is transferred from the toner storage chamber 18a to the toner storage chamber 18a. Do not return to. As described above, the toner storage chamber transport member 22 does not enter the buffer chamber 18c, and the lower end 44a of the first opening 44 is set to a position higher than the rotation center of the toner storage chamber transport member 22. Reduction of the return of toner from the toner storage chamber 18a to the toner storage chamber 18a is realized.

[Supplementary Method for Preventing Return of Toner from Developing Chamber 18b to Toner Storage Chamber 18a]
FIGS. 15A to 15D are schematic views illustrating various configurations of the first opening 44. Referring to FIGS. 15A to 15D, the following method is captured as a method for preventing the toner from returning from the developing chamber 18b to the toner storage chamber 18a. The first openings 44 in FIGS. 15A to 15D are different in length and position in the longitudinal direction. 15A to 15D correspond to views seen from the direction of arrow V in FIG. For example, as shown in FIG. 15A, the first opening 44 may be formed only in part in parallel to the longitudinal direction of the toner storage chamber transport member 22. According to such a configuration, once the toner has accumulated in the developing chamber 18b, it can return to the toner storage chamber 18a only from a part of the longitudinal position of the first opening 44. As a result, the return of toner from the developing chamber 18b to the toner storage chamber 18a is prevented.

  FIG. 15B shows an example in which the second opening 45 between the buffer chamber 18c and the developing chamber 18b is provided only in a part of the longitudinal position. 15B shows the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c and the second opening 45 between the buffer chamber 18c and the developing chamber 18b, as viewed from the direction of the arrow V shown in FIG. It is a block diagram which shows a longitudinal positional relationship. As shown in FIG. 15B, the second opening 45 may be formed only in part in parallel with the longitudinal direction of the toner storage chamber transport member 22. According to such a configuration, the toner once accumulated in the developing chamber 18b can return to the toner storage chamber 18a only from the second opening 45 between the buffer chamber 18c and the developing chamber 18b, which is a part of the longitudinal position. Accordingly, it is possible to realize that the toner hardly returns from the developing chamber 18b to the toner storage chamber 18a.

  FIG. 15C shows an example in which the length from the rotation center to the outermost part of the toner storage chamber conveyance member 22 differs in the longitudinal position. FIG. 15C is a configuration diagram showing the longitudinal positional relationship between the toner storage chamber transport member 22 and the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c as viewed from the direction of the arrow V shown in FIG. . As shown in FIG. 15C, the dimension of the toner storage chamber transport member 22 from the transport support shaft 22 b to the outermost peripheral portion may be different for each position in the longitudinal direction of the toner storage chamber transport member 22. According to such a configuration, the toner once accumulated in the developing chamber 18b can return to the toner storing chamber 18a only from the first opening 44 between the toner storing chamber 18a and the buffer chamber 18c, which is a part of the longitudinal position. Further, the shape of the toner storage chamber transport member 22 is adjusted to the longitudinal position of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c as shown in FIG. The toner can be easily conveyed to the buffer chamber 18c. Accordingly, it is possible to simultaneously realize that toner can be replenished from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed and that the toner is difficult to return from the developing chamber 18b to the toner storage chamber 18a.

  FIG. 15D shows an example in which the shape of the first opening 44 between the toner storage chamber 18a and the buffer chamber 18c or the shape of the second opening 45 between the buffer chamber 18c and the developing chamber 18b differs in the longitudinal position. 15D shows a first opening 44 between the toner storage chamber 18a and the buffer chamber 18c and a second opening 45 between the buffer chamber 18c and the developing chamber 18b, as viewed from the direction of the arrow V shown in FIG. It is a block diagram which shows the longitudinal positional relationship of these. As shown in FIG. 15D, the shapes of the first opening 44 and the second opening 45 may be different for each position in the longitudinal direction of the toner storage chamber transport member 22. Specifically, the difference in height between the lower end 44a of the opening between the toner storage chamber 18a and the buffer chamber 18c and the upper end 45a of the opening 45 between the buffer chamber 18c and the developing chamber 18b is greater at the longitudinal center than at both ends. . Here, the larger the difference in height between the lower end 44a of the opening between the toner storage chamber 18a and the buffer chamber 18c and the upper end 45a of the opening between the buffer chamber 18c and the developing chamber 18b, the larger the difference from the developing chamber 18b to the toner storage chamber 18a. The toner is difficult to return. Accordingly, the toner in the center of the longitudinal direction is less likely to return from the developing chamber 18b to the toner storage chamber 18a than the longitudinal ends. The toner once accumulated in the developing chamber 18b can return to the toner storage chamber 18a only from a part of the longitudinal position. In this way, the difference in height between the lower end 44a of the first opening 44 and the upper end 45a of the opening between the buffer chamber 18c and the developing chamber 18b is made different in the longitudinal position, so that the developing chamber 18b and the toner storage chamber are different. It can be realized that the toner hardly returns to 18a.

[Height relationship between the opening 45 and the stirring member 31]
FIG. 15E is a cross-sectional view showing the configuration of the developing unit. FIG. 15 (e) shows the height relationship between the second opening 45 and the stirring member 31. In Embodiments 2 to 4, as shown in FIG. 15E, the second opening 45 between the buffer chamber 18c and the developing chamber 18b is between the horizontal line G1 and the horizontal line G2, and the rotation region of the stirring member 31 Is between the horizontal line G3 and the horizontal line G4. Accordingly, the second opening 45 partially overlaps with the rotation region of the stirring member 31 in the vertical direction. With this setting, when there is no toner in the developing chamber 18b near the second opening 45, toner in the buffer chamber 18c near the lower end 45b of the second opening 45 is transferred from the buffer chamber 18c to the developing chamber 18b. It is easy to collapse. Then, the toner can smoothly move from the buffer chamber 18c to the developing chamber 18b. As a result, toner replenishment is realized from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed.

[Height relationship between stirring member and developer supply body]
FIG. 15E shows the height relationship between the stirring member 31 and the supply roller 20. In Examples 2 to 4, as shown in FIG. 15E, the rotation region of the stirring member 31 is between the horizontal line G3 and the horizontal line G4, and the supply roller 20 is between the horizontal line G5 and the horizontal line G6. . Therefore, the rotation region of the stirring member 31 partially overlaps the supply roller 20 in the vertical direction. With this setting, the toner accumulated on the developing chamber bottom surface 26 b by the stirring member 31 is efficiently sent to the supply roller 20. As a result, the toner supply from the supply roller 20 to the developing roller 17 can be stabilized, and the occurrence of image defects such as image unevenness due to poor toner supply can be suppressed.

[Sheet length of stirring member]
Fig.16 (a) is a side view which shows the structure of the stirring member 31 of Examples 2-4, and the structure of the modification. As shown in FIG. 16 (a), two sheet portions 31a are attached to two surfaces of the rotating shaft 31b having different 180 ° phases. The length from the center of the rotating shaft 31b to the tip of the sheet portion 31a is the same at any longitudinal position. However, the length from the center of the rotating shaft 31b to the tip of the sheet portion 31a is not necessarily limited to this configuration. As will be described in detail below with reference to FIGS. 16B and 16C, the dimension from the rotation center to the outermost periphery of the stirring member 31 is different for each position in the longitudinal direction of the stirring member 31. May be set.

  FIG. 16B is a cross-sectional view showing the configuration of the first example in which the length from the center of the rotation shaft 31b to the tip of the sheet portion 31a is different in the longitudinal position. As shown in FIG. 16B, the length from the center of the rotation shaft 31b to the tip of the sheet portion 31a1 is longer at the right end of the sheet portion 31a1 than at the left end. On the contrary, the length from the center of the rotating shaft 31b to the tip of the sheet part 31a2 is longer at the left end of the sheet part 31a2 than at the right end. Here, the right end of the sheet portion 31a1 is in contact with the bottom surface of the developing chamber, but the left end of the sheet portion 31a1 is set not to contact the bottom surface of the developing chamber. The left end of the sheet portion 31a2 is in contact with the bottom surface of the developing chamber, but the right end of the sheet portion 31a2 is set so as not to contact the bottom surface of the developing chamber.

  According to such a configuration, the rotation of the leading end of the sheet portion 31a1 is delayed at the right end of the sheet portion 31a1 than at the left end, and the toner is sent from the left end to the right end. Further, the rotation of the leading end of the sheet portion 31a2 is delayed at the left end of the sheet portion 31a2 than at the right end, and the toner is sent from the right end to the left end. As described above, by using the stirring member 31 having a different length from the center of the rotation shaft 31b to the tip of the sheet portion 31a at the longitudinal position, the toner inside the developing chamber 18b can be stirred in the longitudinal direction. In addition, the toner can be efficiently mixed in the longitudinal direction by having two or more sheet portions 31a capable of feeding toner in different longitudinal directions. As a result, the new toner and the deteriorated toner inside the developing chamber 18b can be sufficiently mixed in the longitudinal direction, and the ratio of the new toner and the deteriorated toner is prevented from being different at the longitudinal position inside the developing chamber 18b. can do. As a result, “fogging” on the white background of the image caused by electrostatic aggregation of new toner and deteriorated toner, or a difference in image density between a portion with a lot of new toner and a portion with a small amount of toner in one image. Image defects such as “density unevenness” can be prevented.

  FIG. 16C is a cross-sectional view showing the configuration of the second example in which the length from the center of the rotation shaft 31b to the tip of the sheet portion 31a is different in the longitudinal position. As shown in FIG. 16C, the sheet part 31a3 and the sheet part 31a4 are longer in the center from the center of the rotation shaft 31b to the tip of the sheet part 31a than at both ends. Here, the centers of the sheet portion 31a3 and the sheet portion 31a4 are in contact with the bottom surface of the developing chamber, but both ends of the sheet portion 31a3 and the sheet portion 31a4 are set so as not to be in contact with the bottom surface of the developing chamber. In such a setting, the rotation of the leading end of the sheet portion 31a is delayed in the center of the sheet portion 31a3 and the sheet portion 31a4 than the both ends, and the toner is sent from both ends to the center. As described above, by using the stirring member 31 whose length from the center of the rotation shaft 31b to the tip of the sheet portion 31a is different in the longitudinal position, the toner inside the developing chamber 18b can be stirred in the longitudinal direction.

[Rotation direction of stirring member]
FIG. 16D is an explanatory diagram showing the rotation direction of the stirring member 31 in the developing unit 98. In Examples 2 to 4, as illustrated in FIG. 16D, the stirring member 31 rotates so that the surface moves from the bottom to the top at the portion facing the second opening 45. With this setting, the toner near the second opening 45 is raised inside the buffer chamber 18c.

  Then, it is possible to prevent the toner inside the buffer chamber 18c from excessively falling into the developing chamber 18b. Therefore, mixing of the toner inside the buffer chamber 18c and the toner inside the developing chamber 18b is prevented. Thereby, the return of toner from the developing chamber 18b to the toner storage chamber 18a can be reduced. However, the direction of rotation of the stirring member 31 is not limited, and the stirring member 31 may rotate so that the surface moves from top to bottom at the portion facing the second opening 45. In the first embodiment, the supply roller 20 rotates so that the surface moves from the top to the bottom at the portion facing the second opening 45. However, the present invention is not limited to this configuration and may rotate in the opposite direction. .

[Shaping member shape and material]
In Examples 2 to 4, the agitating member 31 includes a flexible sheet portion 31a as an agitating portion for agitating the toner, and a rotating shaft 31b to which the sheet portion 31a is attached and for receiving a rotational driving force. have. By using such a stirring member 31, the toner can be efficiently stirred and transported. However, it is not necessarily limited to the shape and material of such a stirring member. For example, a hole through which toner can pass may be provided in the sheet portion 31a. Further, a rigid material that is not flexible may be used.

[Number of sheets of stirring member]
In Examples 2-4, the rotating shaft 31b which attached two sheet | seat parts 31a to 2 surfaces of the rectangular-shaft-shaped rotating shaft 31b was used. By affixing the two sheet portions 31a, the amount of toner supplied to the supply roller 20 can be increased, toner supply from the supply roller 20 to the developing roller 17 can be stabilized, and image unevenness due to poor toner supply. It is possible to suppress the occurrence of image defects such as. However, it is not limited to this configuration. For example, a plurality of sheet portions 31a may be attached to a plurality of surfaces of the polygonal column-shaped rotation shaft 31b.

[Process cartridge type]
In the first to fourth embodiments, the developing unit 4 and the photosensitive unit 13 are integrally formed into a cartridge so that the process cartridge 7 is detachable from the image forming apparatus 100. However, it is not limited to this configuration. For example, the present invention similarly applies to an image forming apparatus having a configuration in which the photosensitive drum 1 is fixedly disposed on the image forming apparatus 100 and only the developing unit 4 is replaced as a cartridge (developing cartridge) that is detachable from the image forming apparatus 100. Can be applied. Alternatively, the present invention can be similarly applied to an image forming apparatus configured to fix the developing unit 4 to the image forming apparatus 100 and supply toner to the developing unit 4.

  As described above, according to the developing units of Embodiments 1 to 4 and the other embodiments, the lower end 44a of the first opening 44 is connected to the transport support shaft 22b of the toner storage chamber transport member 22 and the upper end 45a of the second opening 45. Higher than. Thus, the amount of toner returned from the developing chamber 18b to the toner storage chamber 18a is reduced. On the other hand, the lower end 45b of the second opening 45 is formed continuously with the developing chamber bottom surface 26c of the developing chamber 18b, and the developing chamber bottom surface 26c of the developing chamber 18b is connected to the horizontal line a at the lower end 45b of the second opening 45. The angle to be formed is set larger than the repose angle of the one-component developer. Thus, the toner supply from the toner storage chamber 18a to the developing chamber 18b is performed at a sufficient speed. As a result, depending on the internal shape of the apparatus, the return of toner from the developing chamber 18b to the toner storage chamber 18a can be suppressed, and toner can be replenished from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed. .

  Further, according to the developing units of the first to fourth embodiments, a separate control mechanism for supplying toner is not necessary for supplying toner from the toner storage chamber 18a to the developing chamber 18b. As a result, cost reduction of the developing unit is realized. Further, a development unit that can be used stably over a long period of time is provided. In Examples 1 to 4, supply control is not performed, but supply control may be performed. For example, the developing device is provided with a means for detecting toner deterioration, and when toner deterioration is detected, the toner is forcibly discharged from the developing chamber 18b, and the toner is transferred from the toner storage chamber 18a to the developing chamber 18b using the present invention. May be replenished. As a result, since toner that has deteriorated significantly does not accumulate in the developing chamber 18b, toner fusion to members inside the developing device can be prevented, and the developing device can be used stably over a long period of time. be able to.

  Further, according to the developing units of Embodiments 1 to 4, the process cartridge 7 and the developing unit 4 are disposed vertically below the intermediate transfer belt 5. A fixing device 10 is disposed above the intermediate transfer belt 5. A phenomenon (influence) in which heat of the fixing device 10 is transferred to a distant position such as the process cartridge 7, the developing unit 4, and the scanner unit 3 is reduced due to the region of the intermediate transfer belt 5. Since the space reserved for suppressing such a phenomenon can be eliminated or reduced, the height of the image forming apparatus 100 is reduced, and the size of the image forming apparatus 100 is reduced.

  Further, according to the developing units of Embodiments 1 to 4, since the stirring member 31 uses the outside of the buffer chamber 18c as a rotation region, the stirring member 31 does not rotate inside the buffer chamber 18c. As a result, the phenomenon that the toner returns from the developing chamber 18b to the toner storage chamber 18a through the buffer chamber 18c due to the rotation of the stirring member 31 is suppressed.

  Further, according to the developing units of Embodiments 1 to 4, after the stirring member 31 sufficiently mixes the new toner and the deteriorated toner in the stirring chamber 18d, the toner is supplied into the developing chamber 18b. As a result, the fogging phenomenon on the white background of the image caused by electrostatic aggregation of new toner and deteriorated toner, or the density where the image density is different between the areas with a lot of new toner and the areas with a small amount of new toner. Image defects such as unevenness are suppressed.

  Further, according to the developing units of Embodiments 1 to 4, the stirring member 31 and the stirring member 25 are disposed inside the developing chamber 18b. As a result, the new toner and the deteriorated toner are sufficiently mixed by the rotation of the stirring member 31. At the same time, the toner is efficiently carried on the supply roller 20 by the movement of the stirring member 25.

  According to the developing unit 84 of the third embodiment, after the new toner and the deteriorated toner are sufficiently mixed using the stirring member 31 in the stirring chamber 18d, the toner is supplied to the developing chamber 18b. For this reason, the “fogging” of the image white background caused by electrostatic aggregation of the new toner and the deteriorated toner, or the difference in image density between the portion with a lot of new toner and the portion with a small amount in one image. Image defects such as “density unevenness” can be prevented.

  Further, according to the developing unit 84 of the third embodiment, the stirring unit 25a is swingably disposed between the supply roller 20 inside the developing chamber 18b and the partition wall 26 separating the developing chamber 18b and the toner storage chamber 18a. Has been established. Thereby, the toner supplied to the developing chamber 18b can be agitated, and the toner supply to the supply roller 20 can be promoted. Therefore, the toner supply from the supply roller 20 to the developing roller 17 can be stabilized, and it is possible to suppress the occurrence of image defects such as image unevenness due to the toner supply failure.

  According to the developing unit 94 of Embodiment 4, the stirring member 31 reduces the return of toner from the developing chamber 18b to the toner storage chamber 18a, and the toner from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed. At the same time, replenishment is possible. Further, the toner supplied to the developing chamber 18 b can be stirred by the stirring member 25, and the toner supply to the supply roller 20 can be promoted. As described above, in one of the two stirring members, toner return from the developing chamber 18b to the toner storage chamber 18a can be reduced, and toner can be replenished from the toner storage chamber 18a to the developing chamber 18b at a sufficient speed. It is possible to have a function to realize what is possible at the same time. On the other hand, the function of further promoting the toner supply to the supply roller 20 can be provided. These functions can be realized with a simple configuration in which the developing chamber 18b is not controlled to replenish new toner from the toner storage chamber 18a and the replenishing means is simple. Accordingly, new toner can be supplied from the toner storage chamber 18a to the developing chamber 18b at low cost, and a developing device that can be used stably over a long period of time can be provided. Further, the toner supply from the supply roller 20 to the developing roller 17 can be stabilized, and it is possible to suppress the occurrence of image defects such as image unevenness due to poor toner supply.

18a Toner storage chamber (first chamber)
18b Development chamber (third chamber)
18c Buffer room (second room)
22 Toner storage chamber transport member (first chamber transport member)
22b Transport support shaft 26c Developing chamber bottom 44 First opening (first opening)
44a lower end 45 second opening (second opening)
45a upper end 45b lower end

Claims (18)

A first chamber containing a one-component developer;
A first opening formed in an upper portion of the first chamber;
A first chamber conveying member that is provided inside the first chamber and supplies a one-component developer from the inside of the first chamber to the first opening;
A second chamber connected to the first chamber via the first opening;
A second opening formed at a position different from the first opening of the second chamber;
A third chamber connected to the second chamber via the second opening, and provided inside the developing device main body;
The lower end of the first opening is set higher than the rotation center of the first chamber transfer member and the upper end of the second opening,
The lower end of the second opening is formed continuously with the bottom of the third chamber, and the angle at which the bottom of the third chamber forms a horizontal line at the lower end of the second opening is a one-component developer. A developing device characterized in that it is set to be larger than the angle of repose.   2. The developing device according to claim 1, further comprising a third chamber stirring member provided inside the third chamber and having the outside of the second chamber as a rotation region. The third chamber is a fourth chamber partitioned by a partition wall;
A third opening that is formed in the partition wall and connects the third chamber and the fourth chamber;
Inside the fourth chamber, a fourth chamber stirring member is disposed,
The third chamber agitating member is disposed in the third chamber in a region adjacent to the fourth chamber, and a developer carrying member that is rotatable while carrying a one-component developer, and the developer The developing device according to claim 2, wherein a developer supply body capable of supplying a one-component developer to the carrier is disposed.   The developing device according to claim 1, wherein two or more third chamber agitating members are disposed inside the third chamber.   The angle formed by the imaginary straight line connecting the lowest position of the lower end of the second opening and the bottom surface of the third chamber with the horizontal line is set larger than the repose angle of the one-component developer. The developing device according to any one of claims 1 to 4.   The bottom surface continuous from the lower end of the second opening to the lowest position of the bottom surface of the third chamber is disposed on the side closer to the lower end of the second opening, and the inclination angle is larger than the repose angle of the one-component developer. A first region formed large, and a second region disposed on a side farther from the lower end of the second opening and formed to have an inclination angle smaller than the repose angle of the one-component developer. The developing device according to any one of claims 1 to 5.   The angle formed by the imaginary straight line connecting the lower end of the first opening and the upper end of the second opening with the horizontal line is set larger than the repose angle of the one-component developer. Item 7. The developing device according to any one of Items 6.   8. The developing device according to claim 1, wherein the first chamber transport member has a rotation area outside the second chamber. 9.   9. The developing device according to claim 1, wherein the first opening is formed only in part in parallel to a longitudinal direction of the first chamber conveyance member. 10.   10. The developing device according to claim 1, wherein the second opening is formed only in part in parallel with a longitudinal direction of the first chamber conveyance member. 11.   11. The dimension from the rotation center of the first chamber transport member to the outermost peripheral portion is different for each position in the longitudinal direction of the first chamber transport member. The developing device described.   12. The development according to claim 1, wherein shapes of the first opening and the second opening are different for each position in the longitudinal direction of the first chamber conveyance member. apparatus.   The developing device according to any one of claims 2 to 12, wherein the second opening and the rotation region of the third chamber stirring member partially overlap in the height direction.   Inside the third chamber, a developer carrier that can be rotated while developing a one-component developer on an image carrier, and a developer supply that can be rotated while supplying the one-component developer to the developer carrier. 14. The rotating region of the third chamber stirring member and the developer supply body partially overlap in the height direction. The developing device according to claim 1.   The dimension from the rotation center of the third chamber agitating member to the outermost peripheral portion differs for each position in the longitudinal direction of the third chamber agitating member. The developing device described.   The developing device according to any one of claims 2 to 14, wherein the third chamber stirring member includes a plurality of sheets having different shapes in the longitudinal direction.   The third chamber agitating member rotates in a direction from the bottom to the top of the second opening at a position before the second opening. 2. The developing device according to item 1. An image forming unit for forming an image;
A developing device according to any one of claims 1 to 17,
An image forming apparatus comprising:

Images