JP2021028696A - Development device - Google Patents

Abstract

To suppress a developer from being flipped up in the vicinity of a developer discharge port.SOLUTION: A development chamber 23 has, regarding a first direction D1, a first area 71 that is an area from an upstream end of a developer discharge port 40 to a downstream end thereof, a second area 72 that is an area adjacent to an upstream side of the first area 71, a third area 73 that is an area adjacent to a downstream side of the first area 71, and a fourth area 74 that is an area adjacent to an upstream side of the second area 72, in which at least one part of the area overlaps a maximum image area A1. A first conveyance screw 25 has: a revolving shaft 70 that is provided over at least the fourth area 74, second area 72, first area 71, and third area 73; and a screw blade 76 that is formed around the revolving shaft 70 in at least the fourth area 74. In the first area 71, second area 72 and third area 73, the screw blade 76 is not formed in the revolving shaft 70, and regarding the first direction D1, the third area 73 is longer than the second area 72.SELECTED DRAWING: Figure 4

Description

The present invention relates to a developing device applied to an image forming device such as a copier, a printer, a facsimile, and a multifunction device having a plurality of these functions.

As a developing device applied to an electrophotographic image forming apparatus, the developing agent is replenished by a replenishing device in order to suppress deterioration of the charging performance of the developing agent, and the surplus developing agent in the developing container that becomes excessive due to the replenishment is removed. It is known that the developer is discharged from a developer discharge port provided on the wall surface of the developing container. As a developing device of this type, a configuration has been proposed in which the screw blades of the transport screw facing the developer discharging port are omitted to prevent excessive discharge of the developing agent from the developing agent discharging port (Patent Document). 1).

Japanese Unexamined Patent Publication No. 2015-22239

By the way, in the developing apparatus, the air pressure in the developing container may rise due to the air being taken into the developing container by the rotation of the developing sleeve (developer carrier). The air taken into the developing container by the developing sleeve is discharged from the developing agent discharge port through the developing agent transport path in the developing container, so that the internal pressure in the developing container is maintained constant. However, when air is discharged from the developer discharge port, the developer splashed by the rotation of the transport screw in the vicinity of the developer discharge port may be discharged from the developer discharge port in the air flow. There is.

Here, in the configuration described in Patent Document 1, since the screw blade is omitted in the portion facing the developer discharge port, it is possible to suppress the jumping up of the developer in the portion facing the developer discharge port. It is possible. However, with the configuration described in Patent Document 1, it is not possible to sufficiently suppress the flip-up of the developer due to the rotation of the screw blades in the vicinity of the upstream side and the downstream side of the developer discharge port in the developer transport direction. Then, when the developer is flipped up in the vicinity of the upstream side and the downstream side of the developer discharge port in this way, the splashed developer rides on the air flow when air is discharged from the developer discharge port. There is a risk that it will be discharged from the developer discharge port.

An object of the present invention is to provide a developing device capable of suppressing the splashing of a developing agent in the vicinity of a developing agent discharge port.

The developing apparatus of the present invention is a developing container for accommodating a developing agent, and is provided in a first chamber and above or below the first chamber, and forms a circulation path for the developing agent together with the first chamber. The developing container having a chamber, a developing agent carrier that carries and rotates a developing agent supplied from the first chamber or the second chamber, and a developing agent carrier that is arranged in the first chamber and is arranged in the first chamber. A first transport screw for transporting the developer in the first direction, and a second transport screw arranged in the second chamber for transporting the developer in the second chamber in a second direction opposite to the first direction. A transport screw, a first communication port that vertically separates the first chamber and the second chamber inside the developing container, and delivers a developer from the second chamber to the first chamber, and the first communication. A partition wall provided on the downstream side of the first direction from the mouth and having a second communication port for passing the developing agent from the first chamber to the second chamber, and in the first chamber, with respect to the first direction. A developing apparatus provided between the second communication port and the maximum image region of the developing agent carrier, and provided with a developing agent discharging unit for discharging excess developing agent in the developing container from the developing container. The first chamber is adjacent to the first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction, and is the first. A second region, which is at least a part of the region from the region to the maximum image region, and a third region, which is adjacent to the downstream side of the first region and is a region within a predetermined range from the downstream end of the first region. And a fourth region adjacent to the upstream side of the second region and at least a part of which overlaps with the maximum image region, and the first transport screw is at least the fourth region, said. It has a rotating shaft provided over a second region, the first region, and the third region, and a screw blade spirally formed around the rotating shaft in at least the fourth region. In one region, the second region, and the third region, the screw blade is not formed on the rotation axis, and the length of the third region is larger than the length of the second region in the first direction. It is characterized by being long.

Further, the developing apparatus of the present invention is a developing container for accommodating a developing agent, which is provided in a first chamber and above or below the first chamber, and forms a circulating path for the developing agent together with the first chamber. The developing container having the second chamber, the developing agent carrier that carries and rotates the developing agent supplied from the first chamber or the second chamber, and the developing agent carrier that is arranged in the first chamber and is arranged in the first chamber. A first transport screw that transports the developer in one chamber in the first direction, and a second that is disposed in the second chamber and transports the developer in the second chamber in a second direction opposite to the first direction. The transport screw of 2, the first communication port that separates the first chamber and the second chamber vertically inside the developing container, and delivers the developer from the second chamber to the first chamber, and the first passage. A partition wall provided on the downstream side in the first direction from the first communication port and having a second communication port for delivering a developing agent from the first chamber to the second chamber, and the first chamber in the first chamber. Development provided between the second communication port and the maximum image region of the developer carrier in terms of direction, and a developer discharge unit for discharging the surplus developer in the developing container from the developing container. The first chamber of the apparatus is adjacent to a first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction. A second region, which is at least a part of the region between the first region and the maximum image region, and a region adjacent to the downstream side of the first region and within a predetermined range from the downstream end of the first region. The first transport screw has at least the fourth region, which has three regions and a fourth region which is adjacent to the upstream side of the second region and at least a part of which overlaps with the maximum image region. A rotating shaft provided over the second region, the first region, and the third region, and a screw blade spirally formed around the rotating shaft in at least the fourth region. In the first region, the second region, and the third region, the screw blade is not formed on the rotation axis, and the length of the third region is 10 mm or more in the first direction. It is a feature.

Further, the developing apparatus of the present invention is a developing container for accommodating a developing agent, which is provided in a first chamber and above or below the first chamber, and forms a circulating path for the developing agent together with the first chamber. The developing container having the second chamber, the developing agent carrier that carries and rotates the developing agent supplied from the first chamber or the second chamber, and the developing agent carrier that is arranged in the first chamber and is arranged in the first chamber. A first transport screw that transports the developer in one chamber in the first direction, and a second that is disposed in the second chamber and transports the developer in the second chamber in a second direction opposite to the first direction. The transport screw of 2, the first communication port that separates the first chamber and the second chamber vertically inside the developing container, and delivers the developer from the second chamber to the first chamber, and the first passage. A partition wall provided on the downstream side in the first direction from the first communication port and having a second communication port for delivering a developing agent from the first chamber to the second chamber, and the first chamber in the first chamber. Development provided between the second communication port and the maximum image region of the developer carrier in terms of direction, and a developer discharge unit for discharging the surplus developer in the developing container from the developing container. The first chamber of the apparatus is adjacent to a first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction. A second region, which is at least a part of the region between the first region and the maximum image region, and a region adjacent to the downstream side of the first region and within a predetermined range from the downstream end of the first region. The first transport screw has at least the fourth region, which has three regions and a fourth region which is adjacent to the upstream side of the second region and at least a part of which overlaps with the maximum image region. A rotating shaft provided over the second region, the first region, and the third region, and a first screw blade spirally formed around the rotating shaft in at least the fourth region, and the above. In at least a part of the first region, the second region, and the third region, a second screw blade having an outer diameter smaller than the outer diameter of the first screw blade formed spirally around the rotation axis is provided. It is characterized in that the length of the third region is longer than the length of the second region in the first direction.

Further, the developing apparatus of the present invention is a developing container for accommodating a developing agent, which is provided in a first chamber and above or below the first chamber, and forms a circulating path for the developing agent together with the first chamber. The developing container having the second chamber, the developing agent carrier that carries and rotates the developing agent supplied from the first chamber or the second chamber, and the developing agent carrier that is arranged in the first chamber and is arranged in the first chamber. A first transport screw that transports the developer in one chamber in the first direction, and a second that is disposed in the second chamber and transports the developer in the second chamber in a second direction opposite to the first direction. The transport screw of 2, the first communication port that separates the first chamber and the second chamber vertically inside the developing container, and delivers the developer from the second chamber to the first chamber, and the first passage. A partition wall provided on the downstream side in the first direction from the first communication port and having a second communication port for delivering a developing agent from the first chamber to the second chamber, and the first chamber in the first chamber. Development provided between the second communication port and the maximum image region of the developer carrier in terms of direction, and a developer discharge unit for discharging the surplus developer in the developing container from the developing container. The first chamber of the apparatus is adjacent to a first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction. A second region, which is at least a part of the region between the first region and the maximum image region, and a region adjacent to the downstream side of the first region and within a predetermined range from the downstream end of the first region. The first transport screw has at least the fourth region, which has three regions and a fourth region which is adjacent to the upstream side of the second region and at least a part of which overlaps with the maximum image region. A rotating shaft provided over the second region, the first region, and the third region, and a first screw blade spirally formed around the rotating shaft in at least the fourth region, and the above. In at least a part of the first region, the second region, and the third region, a second screw blade having an outer diameter smaller than the outer diameter of the first screw blade formed spirally around the rotation axis is provided. It is characterized in that the length of the third region is 10 mm or more with respect to the first direction.

According to the present invention, it is possible to suppress the splashing of the developer in the vicinity of the developer discharge port.

It is sectional drawing of the schematic structure of the image forming apparatus which concerns on 1st Embodiment. It is sectional drawing of the schematic structure of the developing apparatus which concerns on 1st Embodiment. It is sectional drawing of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on 1st Embodiment, and a developer discharge port. It is an enlarged sectional view of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on 1st Embodiment, and a developing agent discharge port. It is an enlarged sectional view of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on 2nd Embodiment, and a developing agent discharge port. It is sectional drawing of the schematic structure which shows the 1st transport screw in the developing container of the developing apparatus which concerns on 2nd Embodiment, (a) is a screw blade on the upstream side of a developer discharge port, (b) is a developer. It is a screw blade on the downstream side of the discharge port. It is an enlarged sectional view of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on 3rd Embodiment, and the developing agent discharge port. It is an enlarged cross-sectional view of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on 4th Embodiment, and the developing agent discharge port. It is sectional drawing of the schematic structure which shows the relationship between the 1st transport screw in the developing container of the developing apparatus which concerns on a comparative example, and a developing agent discharge port.

<First Embodiment>
The first embodiment of the present invention will be described with reference to FIGS. 1 to 4. First, the schematic configuration of the image forming apparatus 100 of the present embodiment will be described with reference to FIG.

[Image forming device]
The image forming apparatus 100 of the present embodiment is a full-color image forming apparatus adopting an electrophotographic method, and includes four image forming units P (Pa, Pb, Pc, Pd). Since the configurations of the image forming units P are substantially the same except that the developing colors are different, the image forming unit Pa will be described below as a representative.

The image forming unit Pa includes a drum-shaped electrophotographic photosensitive member that rotates in the arrow direction (counterclockwise direction) as an image carrier that supports a toner image, that is, a photosensitive drum 1a. The photosensitive drum 1a has a diameter of, for example, 30 mm. An image forming means including a charging device 2a, a laser beam scanner 3a as an exposure means, a developing device 4a, a transfer roller 6a, a cleaning means 19a, and the like is provided around the charger.

Next, an image forming sequence in the normal mode of the entire image forming apparatus 100 having the above configuration will be described. First, the photosensitive drum 1a is uniformly charged by the charger 2a. In the normal mode, the photosensitive drum 1a rotates in the counterclockwise direction indicated by the arrow at a process speed (peripheral speed) of, for example, 217 rpm. The uniformly charged photosensitive drum 1a is then subjected to scanning exposure by a laser beam scanner 3a with a laser beam modulated by an image signal.

The laser beam scanner 3a has a built-in semiconductor laser, and the semiconductor laser is controlled based on the input image data to emit laser light. For example, a laser that is controlled in response to a document image information signal (image data) input from a document reader having a photoelectric conversion element such as a CCD, or in response to an image information signal input from an external terminal. It emits light. As a result, the surface potential of the photosensitive drum 1a charged by the charger 2a changes in the image portion, and an electrostatic latent image is formed on the photosensitive drum 1a. In the present embodiment, such a charger 2a and a laser beam scanner 3a constitute an electrostatic latent image forming means.

The electrostatic latent image thus formed on the photosensitive drum 1a is reverse-developed with toner by the developing device 4a to obtain a visible image, that is, a toner image. In the present embodiment, the developing apparatus 4a uses a two-component developing method in which a developing agent containing toner and a carrier is used as the developing agent. That is, each of the developing devices 4a, 4b, 4c, and 4d contains a two-component developer containing toner of each color. Specifically, yellow (Y) toner is used for the developing device 4a, magenta (M) toner is used for the developing device 4b, cyan (C) toner is used for the developing device 4c, and black is used for the developing device 4d. Each of the toners (K) is stored. Therefore, by performing the above steps for each image forming unit Pa, Pb, Pc, and Pd, four color toner images of yellow, magenta, cyan, and black are formed on the photosensitive drums 1a, 1b, 1c, and 1d, respectively. It is formed.

Further, an intermediate transfer belt 5 which is an intermediate transfer body is arranged at a position below each image forming unit Pa, Pb, Pc, and Pd. The intermediate transfer belt 5 is suspended on the rollers 61, 62, 63 and is movable in the direction of the arrow. The toner image on the photosensitive drum 1a is once sequentially transferred to the intermediate transfer belt 5 which is an intermediate transfer body by the transfer roller 6a as the primary transfer means. As a result, the toner images of four colors of yellow, magenta, cyan, and black are superimposed on the intermediate transfer belt 5 to form a full-color image. Further, the toner remaining without being transferred onto the photosensitive drum 1a is collected by the cleaning means 19a.

The full-color image on the intermediate transfer belt 5 is transferred to a recording material S such as a sheet (paper, OHP sheet, etc.) taken out from the paper feed cassette 12 and advanced via the paper feed roller 13 and the paper feed guide 11. It is transferred by the action of the next transfer roller 10. The toner remaining on the surface of the intermediate transfer belt 5 without being transferred is collected by the intermediate transfer belt cleaning means 18. On the other hand, the recording material S to which the toner image is transferred is sent to the fixing device (thermal roller fixing device) 16, the image is fixed, and the recording material S is discharged to the paper ejection tray 17.

In the present embodiment, the photosensitive drum 1a, which is a drum-shaped organic photoconductor that is usually used, is used as the image carrier, but of course, an inorganic photoconductor such as an amorphous silicon photoconductor can also be used. It is also possible to use a belt-shaped photoconductor. The charging method, transfer method, cleaning method, and fixing method are not limited to the above methods.

[Developer]
Next, the developing apparatus 4a will be described with reference to FIG. The developing apparatus 4a includes a developing container 22 for accommodating a two-component developing agent, a developing sleeve 28 as a developing agent carrier, and first and second transport screws 25 and 26 as transport members. Further, since the developing apparatus 4a of the present embodiment is a vertical stirring type, the inside of the developing container 22 is a developing chamber (No. 1) which is an accommodating portion by a partition wall 27 whose substantially central portion extends in the direction perpendicular to the paper surface. It is divided into upper and lower chambers (1 chamber) 23 and a stirring chamber (2nd chamber) 24. The developer is housed in the developing chamber 23 and the stirring chamber 24. That is, the developing container 22 has a developing chamber 23 and a stirring chamber 24 provided below the developing chamber 23 and forming a circulation path for the developer together with the developing chamber 23. The developing chamber 23 provided above the stirring chamber 24 supplies the developing agent to the developing sleeve 28, and the stirring chamber 24 collects the developing agent from the developing sleeve 28. Further, the developing sleeve 28 supports and rotates the developer supplied from the developing chamber 23.

The first and second transfer screws 25 and 26 are arranged in the stirring chamber 24 and the developing chamber 23, respectively. The first transfer screw 25 is arranged substantially parallel to the bottom of the upper developing chamber 23 along the longitudinal direction (rotational axis direction) of the developing sleeve 28, and rotates clockwise in FIG. 2 to develop the developing chamber 23. The developer in the inside (first chamber) is conveyed while being stirred in one direction along the axial direction. The reason for clockwise rotation is that it is advantageous from the viewpoint of supplying the developing agent to the developing sleeve 28. As shown in FIG. 3, the first transport screw 25 has a rotary shaft 70 and screw blades 76 formed spirally around the rotary shaft 70, and transports the developer in the first direction D1. Further, the second transfer screw 26 is arranged at the bottom of the lower stirring chamber 24 substantially parallel to the first transfer screw 25, and rotates in the opposite direction (counterclockwise) to the first transfer screw 25. .. Then, the developer in the stirring chamber 24 (second chamber) is conveyed while being stirred in the second direction D2 in the direction opposite to the first direction D1 which is the conveying direction of the first conveying screw 25.

The partition wall 27 is provided on the downstream side of the first communication port 27a for passing the developer from the stirring chamber 24 to the developing chamber 23 and the first communication port 27a in the first direction D1, and develops from the developing chamber 23 to the developing chamber 24. It has a second communication port 27b for delivering the agent. Both ends of the partition wall 27 do not reach the inner walls of both ends in the longitudinal direction of the developing container 22, whereby the first communication port 27a for passing the developer from the stirring chamber 24 to the developing chamber 23 and stirring from the developing chamber 23. A second communication port 27b for delivering the developer to the chamber 24 is formed. By the rotation of the first and second transfer screws 25 and 26, the developer circulates between the developing chamber 23 and the stirring chamber 24 through the first communication port 27a and the second communication port 27b at both ends of the partition wall 27. Will be done. In this embodiment, the developing chamber 23 and the stirring chamber 24 are arranged one above the other, and the function of supplying the developing agent to the developing sleeve 28 and the function of collecting the developing agent after development are separated. The case is described, but it is not limited to this. For example, the configuration may not be functional separation.

Further, as shown in FIG. 2, there is an opening at a position corresponding to the development position of the developing container 22 facing the photosensitive drum 1a, and the developing sleeve 28 is partially exposed in the photosensitive drum direction in this opening. It is rotatably arranged. The developing sleeve 28 carries and conveys the developing agent in the developing container, and supplies the developing agent to the developing position of the photosensitive drum 1a. The length (coating amount) of the developing agent spikes (magnetic brush) supported on the developing sleeve 28 is regulated by the regulating blade 29 which is a spike cutting member. Here, the diameter of the developing sleeve 28 is, for example, 20 mm, the peripheral speed is 565 rpm, the diameter of the photosensitive drum 1a is, for example, 30 mm, the peripheral speed is 217 rpm, and the closest region between the developing sleeve 28 and the photosensitive drum 1a is, for example, about 400 μm. The distance. As a result, the spikes of the developer carried on the developing sleeve 28 and whose length is regulated by the regulating blade 29 and conveyed to the developing position are brought into contact with the photosensitive drum 1a to bring the electrostatic latent image on the photosensitive drum 1a. It is set so that it can be developed.

Such a developing sleeve 28 is made of a non-magnetic material such as aluminum or stainless steel, has a diameter of 20 mm, and a magnet roller 28 m, which is a magnetic field generating means, is installed inside the developing sleeve 28 in a non-rotating manner. The magnet roller 28m has a developing electrode S2 arranged so as to face the photosensitive drum 1a at the developing position. Further, it has a magnetic pole S1 arranged to face the regulation blade 29, a magnetic pole N2 arranged between the magnetic poles S1 and S2, and magnetic poles N1 and N3 arranged to face the developing chamber 23 and the stirring chamber 24, respectively. ing.

In this way, the developing sleeve 28 having the magnet roller 28m inside is rotated in the direction of the arrow (clockwise) in FIG. 2 during development, so that the developing agent is carried while being carried. Then, the developer whose layer thickness is regulated by cutting the spikes of the magnetic brush by the regulating blade 29 is conveyed to the developing region facing the photosensitive drum 1a, and the developer is applied to the electrostatic latent image formed on the photosensitive drum 1a. Supply and develop the latent image.

The regulation blade 29 is composed of a non-magnetic member made of plate-shaped aluminum or the like extending along the longitudinal axis of the developing sleeve 28 and a magnetic member such as an iron material, and is a developing sleeve rather than the photosensitive drum 1a. It is arranged on the upstream side in the rotation direction. Then, both the toner and the carrier of the developing agent pass between the tip of the regulating blade 29 and the developing sleeve 28 and are sent to the developing position.

By adjusting the gap between the regulating blade 29 and the surface of the developing sleeve 28, the amount of the developing agent magnetic brush carried on the developing sleeve 28 is regulated and the amount of the developing agent conveyed to the developing position is adjusted. Will be done. In the present embodiment, the regulating blade 29 regulates the amount of the developer coated on the developing sleeve 28 per unit area to, for example, 30 mg / cm ² . Further, the gap between the regulation blade 29 and the developing sleeve 28 is set to 200 to 1000 μm, preferably 300 to 700 μm. In this embodiment, it was set to 400 μm.

Further, in the developing region facing the photosensitive drum 1a, the developing sleeve 28 moves in the forward direction with the moving direction of the photosensitive drum 1a, and the peripheral speed ratio moves 1.75 times with respect to the photosensitive drum 1a. doing. The peripheral speed ratio is set between 0 and 3.0 times, and preferably any number of times as long as it is set between 0.5 and 2.0 times. The larger the moving speed ratio, the higher the developing efficiency, but if it is too large, problems such as toner scattering and deterioration of the developing agent occur. Therefore, it is preferable to set the moving speed ratio within the above range.

Next, a two-component developer containing a toner and a carrier used in the present embodiment will be described. The toner has colored resin particles containing a binder resin, a colorant, and other additives as necessary, and colored particles externally supplemented with an external agent such as colloidal silica fine powder. There is. The toner is a negatively charged polyester resin, and the volume average particle size is preferably 4 μm or more and 10 μm or less. It is more preferably 8 μm or less. In the present embodiment, the average particle size of the toner is set to about 6 μm in consideration of image quality and handleability.

Further, as the carrier, for example, surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium and rare earth, alloys thereof, oxide ferrite and the like can be preferably used, and their magnetism can be used. The method for producing the particles is not particularly limited. Carrier has a weight average particle size of 20 to 60 [mu] m, preferably from 30 to 50 [mu] m, resistivity of 10 ⁷ [Omega] cm or more, preferably 10 ⁸ [Omega] cm or more. In this embodiment, those of 10 ⁸ Ωcm, 50% particle diameter (D50) is used 40μm particles of approximately. In the present embodiment, such toner and carriers are mixed in a developing container 22 at a weight ratio of about 9:91, and the toner concentration (ratio (ratio) of toner weight to total developer weight: TD). It is used as a two-component developer with a ratio of 9%, and contains 350 g as the amount.

Next, the drive control system of the developing device 4a will be described. The developing sleeve 28 is driven by a first drive means motor M1 (not shown) as a developing unit drive means, and the first and second transfer screws 25 and 26 are driven by a second drive means motor M2 (not shown) as a stirring transfer means. It is being driven. In the present embodiment, both of these motors are stepping motors in which the angular acceleration can be set according to the acceleration / deceleration rate when the drive is stopped, and the drive rotation speeds in the steady state at the time of image formation are 565 rpm and 900 rpm, respectively. Further, in the present embodiment, the first drive means motor M1 and the second drive means motor M2 are directly connected to the developing sleeve 28 and the first transfer screw 25, respectively, and further, the first transfer screw 25 and the second transfer screw 25 are used. The transport screw 26 is connected by a gear. Therefore, the developing sleeve 28 and the first transfer screw 25 are driven at 565 rpm and 900 rpm, respectively, and the second transfer screw 26 is driven at 900 rpm.

[Replenishment of developer]
Next, the method of replenishing the developer in this embodiment will be described with reference to FIGS. 2 and 3. A hopper 31 for accommodating a replenishing two-component developer in which toner and carriers are mixed is arranged above the developing device 4a. The hopper 31 constituting the toner replenishment means is provided with a screw-shaped transport member 32 at the lower portion, and one end of the transport member 32 extends to the position of a developer replenishment port 30 provided at the front end portion of the developing device 4a.

The amount of toner consumed by image formation is replenished to the developing container 22 from the hopper 31 through the developing agent replenishing port 30 by the rotational force of the transport member 32 and the gravity of the developing agent. In this way, the developer is supplied from the hopper 31 to the developing device 4a. The replenishment amount of the developer is approximately determined by the number of rotations of the transport member 32, and this number of rotations is determined by a toner replenishment amount control unit (not shown). As a method of controlling the amount of toner replenished, a method of optically or magnetically detecting the toner concentration of the two-component developer, a method of developing a reference latent image on the photosensitive drum 1a, and a method of detecting the density of the toner image, etc. Can be selected as appropriate.

[Discharge of developer]
Next, the method of discharging the developer in this embodiment will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, a developer discharge port 40 is provided on the side wall of the developing container 22 as an example of a developer discharge unit, and the deteriorated developer is discharged from the developer discharge port 40 according to an arrow. .. When the amount of the developing agent in the developing apparatus 4a increases due to the developing agent replenishment step, the developing agent is discharged so as to overflow from the developing agent discharge port 40 according to the increased amount. That is, the developer discharge port 40 discharges the surplus developer accompanying the replenishment of the developer from the developing container 22. The discharged developer is transported to a recovery developer storage (not shown) by a recovery screw 41 which is a transport member.

The developer discharge port 40 is formed at a predetermined height position of the developing container 22 according to a predetermined agent surface height when the developer reaches a steady state. In the present embodiment, the developer discharge port 40 is provided on the side wall of the developing chamber 23 so that the bottom of the opening of the developer discharge port 40 comes at a position 15 mm in height from the bottom surface of the developing chamber 23. The developer discharge port 40 has an opening width of 10 mm in the developer transport direction and 5 mm in height. The shape and size of the developer discharge port 40 are not limited to those described above, and when the internal pressure in the developing container 22 rises, air is discharged from the developer discharge port 40 in order to reduce the internal pressure. It should be.

The position of the developer discharge port 40 is on the upstream side in the developer transport direction from the position of the developer supply port 30, and on the downstream side in the developer transport direction of the side wall of the developing chamber 23 in which the first transport screw 25 is arranged. Is formed in. This is to prevent the replenished new developer from being discharged immediately. As shown in FIG. 3, the developer discharge port 40 is provided in the developing chamber 23 between the second communication port 27b and the maximum image area A1 of the developing sleeve 28 with respect to the first direction D1. In the present embodiment, the maximum image region A1 of the developing sleeve 28 corresponds to the maximum image region of the image regions capable of forming an image on the surface of the photosensitive drum 1a in the direction of the rotation axis of the developing sleeve 28. It is a region of the developing sleeve 28.

[Relationship between developer outlet and first transport screw]
Next, the relationship between the developer discharge port 40 and the first transfer screw 25 will be described with reference to FIG. As described above, the first transport screw 25, which is a transport member, is arranged in the developing chamber 23 of the developing container 22. Further, a developer discharge port 40 is provided on the side wall in the developing chamber 23, and a part of the first transport screw 25 is arranged so as to face the developer discharge port 40.

The first transfer screw 25 has a screw blade 76 formed spirally on the rotating shaft 70, and by rotating, the developer in the developing chamber 23 is conveyed along the rotating shaft 70. In the present embodiment, for example, in the first transport screw 25, screw blades 76 having a pitch of 40 mm and an outer diameter of 18 mm are provided with two threads over the axial direction of the rotating shaft 70 having a shaft diameter of 6 mm. It is formed. The first transfer screw 25 is evenly provided from the first communication port 27a to the front upstream of the developer discharge port 40 beyond the range of the maximum image region A1 of the developing sleeve 28. The second transport screw 26 is formed by providing a screw blade, which is a stirring blade having a pitch of 30 mm and an outer diameter of 18 mm, on a rotating shaft having a shaft diameter of 6 mm in the axial direction and having a number of threads of 1. The developer in the stirring chamber 24 is conveyed.

Here, the phenomenon of the developer being flipped up by the screw blades 76 of the first transfer screw 25 will be described using the developing device 404 shown in FIG. 9, which is a comparative example. As described above, in addition to the surplus developer discharged so as to overflow from the developer discharge port 40, the surplus is caused by the flip-up of the screw blade 76 of the first transport screw 25 facing the developer discharge port 40. The developer that is not used may be discharged. Such a phenomenon of the developer being flipped up by the screw blade 76 occurs in the following process. As the screw blade 76 rotates, the developer in the developing container 22 is conveyed in the first direction D1 which is the transport direction in a form of being pushed by the screw blade 76. At this time, the developer receives a force not only in the first direction D1 but also in the rotation direction as the screw blade 76 rotates. Therefore, the developer is conveyed in the oblique direction by the amount of the force applied in the rotational direction with respect to the first direction D1. As a result, the developer is also flipped up in the side surface direction in which the developer discharge port 40 in the developing chamber 23 is provided. Then, at the portion where the first transport screw 25 faces the developer discharge port 40, the splashed developer is directly discharged from the developer discharge port 40, which causes unnecessary discharge. ing.

As a countermeasure against such a phenomenon of the developer being flipped up, it is conceivable that the screw blade 76 is not provided at the portion where the first transport screw 25 faces the developer discharge port 40. However, even in a configuration in which the screw blade 76 is not provided at the portion facing the developer discharge port 40, a non-surplus developer may be discharged. A phenomenon in which a non-surplus developer is discharged even in a configuration in which the screw blade 76 is not provided at the opposite portion of the developer discharge port 40 will be described below. The inside of the developing container 22 is always maintained at a constant atmospheric pressure while repeatedly inflowing and discharging air even during driving. As shown by the thick arrow in FIG. 9, as the developing sleeve 28 rotates, the developing agent (magnetic spike) coated on the developing sleeve 28 contains air in the magnetic spike and is in the stirring chamber in the developing container 22. It is taken in by 24. As a result, the air pressure in the developing container 22 rises, so that the air taken in by the developing sleeve 28 is discharged from the developing agent discharge port 40 in the developing room 23 through the second communication port 27b from the stirring chamber 24. The internal pressure inside the developing container 22 is kept constant.

At this time, a part of the developer conveyed to the second communication port 27b is flipped up as the screw blades of 0.5 pitch on the downstream side of the first direction D1 from the developer discharge port 40 rotate. Sometimes. The splashed developer is discharged from the developer discharge port 40 along with the air flow flowing from the developing sleeve 28 to the developer discharge port 40, which causes unnecessary discharge. This phenomenon is more likely to occur when the amount of the developer in the developing container 22 is small. Consider a case where an amount of excess developer is stored so that the amount of developer in the developing container 22 overflows from the developer discharge port 40 provided on the side wall of the developing chamber 23. In this case, the height of the developer in the vicinity of the developer outlet 40 in the developing chamber 23 is such that more than half of the screw blades 76 of the first transport screw 25 are filled with the developer. Therefore, even if the 0.5-pitch screw blades on the downstream side of the first direction D1 from the developer discharge port 40 rotate to flip up the developer, they are transported from the upstream of the first transport screw 25. Swallowed by the developer. Therefore, it is possible to prevent the jumped developer from riding on the airflow flowing from the developing sleeve 28 to the developer discharge port 40.

On the other hand, consider a case where the amount of the developer in the developing container 22 is small and the surface of the developing agent is lower than that of the developing agent discharge port 40 provided on the side wall of the developing chamber 23. In this case, since the height of the developer in the vicinity of the developer discharge port 40 of the developing chamber 23 is lower than half of the screw blades 76 of the first transfer screw 25, the developer is conveyed from the upstream of the first transfer screw 25. The amount of developer that comes in is small. Therefore, the developer that the screw blades on the downstream side of the first direction D1 of the developer discharge port 40 rotate and bounce off may be swallowed by the developer that is conveyed from the upstream of the first transfer screw 25. It will be suppressed. Therefore, the splashed developer may be discharged from the developer discharge port 40 on the air flow flowing from the developing sleeve 28 to the developer discharge port 40. In particular, the developer conveyed without the screw blades is likely to be flipped up by suddenly contacting the screw blades located downstream of the developer discharge port 40, and the splashed developer is in the developer discharge port 40. It is easily discharged from the developer discharge port 40 by riding on the airflow flowing from the downstream side to the outside.

In this embodiment, the first transport screw 25 is configured as follows as a countermeasure against the discharge phenomenon of the developer due to such an air flow. As shown in FIG. 4, the developing chamber 23 has a first region 71, a second region 72, a third region 73, and a fourth region 74 with respect to the first direction D1. The first region 71 is a region from the upstream end to the downstream end of the developer discharge port 40 with respect to the first direction D1. For example, in the first direction D1, a plurality of developer discharge ports 40 may be arranged side by side. In this case, it is provided from the upstream end 40b of the developer discharge port 40 located on the most upstream side of the series of developer discharge ports 40 to the downstream end 40a of the developer discharge port 40 located on the most downstream side. It is assumed that it has been done.

The second region 72 is adjacent to the upstream side of the first region 71, and is at least a part of the region between the first region 71 and the maximum image region A1. The third region 73 is adjacent to the downstream side of the first region 71 and is a region within a predetermined range from the downstream end of the first region 71. The fourth region 74 is a region adjacent to the upstream side of the second region 72 and at least a part thereof overlaps with the maximum image region A1. Further, the first transport screw 25 has a rotation shaft 70 provided over at least the fourth region 74, the second region 72, the first region 71, and the third region 73, and the rotation shaft 70 in at least the fourth region 74. It has a screw blade 76 formed spirally around the wheel. Further, in the first region 71, the second region 72, and the third region 73, the screw blade 76 is not formed on the rotating shaft 70.

More specifically, the screw blade 76 is provided so as to end at a position of 15 mm upstream from the center of the developer discharge port 40 in the developer transport direction. That is, starting from a position 15 mm upstream in the developer transport direction from the center of the developer discharge port 40 in the developing chamber 23, to the end of the rotating shaft 70 downstream in the developer transport direction 25 mm away from the center of the developer discharge port 40. It is composed only of a rotating shaft 70 without a screw blade 76. The second communication port 27b is arranged at a position 10 mm away from the center of the developer discharge port 40 downstream in the developer transport direction. Therefore, with respect to the first direction D1, the first region 71 is 10 mm, the second region 72 is 10 mm, and the third region 73 is 20 mm. That is, in the portion without the screw blade 76, the length of the third region 73 is longer than the length of the second region 72 with respect to the first direction D1. Therefore, the screw blades on the downstream side of the developer discharge port 40, which easily flips up the developer, can be sufficiently separated from the developer discharge port 40.

Here, the inventor of the present application has diligently examined the relationship between the dimensions of the second region 72 and the third region 73 and the quality of discharge of the developer that is not a surplus. The results are shown in Table 1. In Table 1, as an evaluation for the discharge of the developer that is not surplus, the ◎ mark means very good suppression, the ○ mark means good suppression, and the × mark means insufficient suppression.

As shown in Table 1, good results were obtained when the third region 73 was longer than the second region 72, and particularly when both the second region 72 and the third region 73 were 10 mm or more. .. Therefore, in the present embodiment, the length of the third region 73 is set to 20 mm, but the length of the third region 73 is not limited to this, and the length of the third region 73 may be longer than the length of the second region 72. Further, the lengths of the second region 72 and the third region 73 are preferably 10 mm or more, respectively.

As described above, in the present embodiment, there is no screw blade 76 in the region of 10 mm or more upstream and downstream of the developer discharge port 40 including the facing portion of the developer discharge port 40 of the first transport screw 25. As a result of diligent studies by the inventors of the present application, by adopting the above-described configuration, it is possible to suppress the developer from splashing up in the vicinity of the developer discharge port 40 even when the amount of the developer in the developing container 22 is small. Therefore, the splashed developer is prevented from riding on the airflow flowing from the developing sleeve 28 to the developer discharge port 40, so that unnecessary developer discharge can be reduced.

In the configuration of the first transport screw 25 of the present embodiment, the transport force is reduced because there is no screw blade 76 for transporting the developer from the downstream of the developer discharge port 40 in the developer transport direction to the second communication port 27b. Will be done. However, since the developer can be transported from the developing chamber 23 to the stirring chamber 24 by the weight of the developer due to gravity, it is possible to prevent the developer from staying downstream of the developing chamber 23.

As described above, according to the developing apparatus 4a of the present embodiment, the first transport screw 25 is a portion without the screw blades 76, and the length of the third region 73 is the second region 72 with respect to the first direction D1. Longer than the length of. As a result, it is possible to suppress the discharge of a non-surplus developer from the developer discharge port 40.

Further, according to the developing apparatus 4a of the present embodiment, the screw blade 76 is not provided on the downstream side of the developing agent discharge port 40. Therefore, the developer is not flipped up by the screw blades 76 on the downstream side of the developer discharge port 40, and the splashing of the developer in the vicinity of the developer discharge port 40 is suppressed even when the amount of the developer is small. can do.

Further, according to the developing apparatus 4a of the present embodiment, since the second region 72 is set to 10 mm, a sufficient distance can be taken between the developer discharge port 40 and the screw blade 76 provided in the fourth region 74. .. Therefore, even if the developer is flipped up by the screw blade 76 on the upstream side of the developer discharge port 40, it hardly reaches the developer discharge port 40, and even when the amount of the developer is small, the developer discharge port 40 It is possible to suppress the splashing of the developer in the vicinity.

<Second embodiment>
A second embodiment of the present invention will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, the developing apparatus 104 of the present embodiment is different from the first embodiment in that the screw blades 77 are provided on the downstream side of the third region 73 of the first transport screw 25. To be different. However, since the other configurations are the same as those in the first embodiment, the same reference numerals are given and detailed description thereof will be omitted.

In the present embodiment, in the first transport screw 25, a spiral screw blade 77 is formed on the rotation shaft 70 in the fifth region 75, which is a region downstream of the third region 73 in the first direction D1. .. The transport direction of the developer by the screw blade 77 is the first direction D1. Here, with respect to the first direction D1, the first region 71 is 10 mm, the second region 72 is 10 mm, and the third region 73 is 10 mm. That is, the screw blade 77 is provided so as to convey the developer at a position 15 mm downstream of the center of the developer discharge port 40 in the first direction D1 so as to overlap the second communication port 27b. .. In this way, the screw blade 77 on the downstream side of the developer discharge port 40, which easily flips up the developer, is provided 10 mm away from the developer discharge port 40.

The screw blade 77 is, for example, assuming that a rotating shaft 70 having a shaft diameter of 6 mm is provided with a spiral blade having a pitch of 40 mm and an outer diameter of 18 mm and having no draft, and having only 0.5 pitch with two threads. There is. Here, the draft is an inclination for smoothly drafting the mold provided in the molded product.

6 (a) and 6 (b) are cross-sectional views with and without a draft, and the directions of the forces received by the developer from the blades are shown by arrows. As shown in FIG. 6A, in the case of the screw blade 76 having a draft, the developer receives a force in the rotation direction (circumferential direction) of the screw blade 76 as the screw blade 76 rotates. Further, since the screw blade 76 has an angle with respect to the perpendicular line v of the rotation shaft 70, the developer is screwed not only in the rotation direction (circumferential direction) but also in the radial direction on the outer peripheral side (outward direction) of the rotation direction. Receives power from the blade 76. Therefore, the developer subjected to the force due to the rotation of the first transport screw 25 is bounced outward.

On the other hand, as shown in FIG. 6B, in the case of the screw blade 77 having no draft, the developer receives a force in the rotation direction (circumferential direction) of the screw blade 77 as the screw blade 77 rotates. .. At this time, since the screw blade 77 having no draft does not have an angle with respect to the perpendicular line of the rotation shaft 70, it does not receive a force in the radial direction on the outer peripheral side (outward) in the rotation direction. Therefore, the developer subjected to the force due to the rotation of the first transfer screw 25 can be conveyed without being flipped up in the outward direction.

The screw blades 76 provided in the fourth region 74 preferably have a draft, and the screw blades 77 provided in the fifth region 75 preferably do not have a draft. The screw blades 76 provided from the first communication port 27a to 15 mm before the center of the developer discharge port 40 with the maximum image region A1 of the developing sleeve 28 sandwiched between them need to be conveyed while supplying the developer to the developing sleeve 28. is there. Since the screw blade 76 has an angle with respect to the perpendicular line v (see FIG. 6A) of the rotating shaft 70, it is possible to efficiently supply the developing agent to the developing sleeve 28 by utilizing the outward radial force. it can.

As described above, according to the developing apparatus 104 of the present embodiment, the first transport screw 25 secures a length of the third region 73 of 10 mm with respect to the first direction D1 and is connected to the developing agent discharge port 40. A sufficient distance from the screw blade 76 provided in the fourth region 74 can be taken. As a result, the screw blade 77 on the downstream side of the developer discharge port 40, which easily flips up the developer, can be sufficiently separated from the developer discharge port 40, and even when the amount of the developer is small, the developer discharge port 40 It is possible to suppress the splashing of the developer in the vicinity.

Further, according to the developing apparatus 104 of the present embodiment, the first transport screw 25 overlaps with the second communication port 27b at a position 15 mm downstream of the first direction D1 from the center of the developer discharge port 40. It has a screw blade 77 that conveys a developer. Therefore, it is particularly effective at a low process speed (rotational speed of the photosensitive drum 1a) at which the transport force is reduced.

For example, when the image forming apparatus 100 has a plurality of process speeds and the process speed is reduced to half speed for media such as thick paper and coated paper, the peripheral speed with that of the photosensitive drum 1a from the viewpoint of developability and deterioration of the developer. In order to keep the ratio constant, the driving speed of the developing device 104 is also set to half speed. In the present embodiment, when the process speed is constant, the developing sleeve 28, the first transfer screw 25, and the second transfer screw 26 are driven at 565 rpm and 900 rpm, respectively. When the process speed is half speed, the developing sleeve 28, the first transfer screw 25, and the second transfer screw 26 are driven at 282.5 rpm and 450 rpm, respectively. When the process speed is half speed, the carrying force is lower than when the process speed is constant. Therefore, when only the rotating shaft 70 is used from the center of the developing agent discharge port 40 to the end of the rotating shaft 70 downstream in the first direction D1, the developing agent is transferred from the developing chamber 23 to the stirring chamber 24 only by the force of its own weight due to gravity. If you try to transport the developer, the developer may stay in the vicinity of the second communication port 27b. On the other hand, according to the configuration of the present embodiment, the screw blade 77 can efficiently convey the developer in the vicinity of the second communication port 27b from the developing chamber 23 to the stirring chamber 24, so that the developing chamber can be used. It is possible to prevent the developer from staying downstream of 23.

In the developing apparatus 104 of the present embodiment described above, the case where the shape of the screw blade 77 on the downstream side of the developing agent discharge port 40 has no draft has been described, but the present invention is not limited to this. For example, the shape of the screw blade 77 may have a draft.

<Third embodiment>
A third embodiment of the present invention will be described with reference to FIG. In the developing apparatus 204 of the present embodiment, the first transfer screw 25 is formed in that the second screw blade 76b is formed in at least a part of the first region 71, the second region 72, and the third region 73. The configuration is different from that of the first embodiment. However, since the other configurations are the same as those in the first embodiment, the same reference numerals are given and detailed description thereof will be omitted.

In the present embodiment, in the first transfer screw 25, the first screw blade 76a, which is the screw blade of the rotating shaft 70, is formed in the fourth region 74. The second screw blade 76b is spirally formed around the rotation shaft 70 in at least a part of the first region 71, the second region 72, and the third region 73, and is smaller than the outer diameter of the first screw blade 76a. It has a diameter. Therefore, in the region where the second screw blade 76b is provided, the flip-up force of the developer can be reduced as compared with the case where the first screw blade 76a is provided. Further, as compared with the case where the screw blades are not provided at all, the transporting force of the developer can be obtained, so that the transportability can be ensured. The second screw blade 76b may be formed in the entire first region 71, the second region 72, and the third region 73, or may be formed only in the second region 72. Further, when the outer diameter of the second screw blade 76b is slightly larger than the outer diameter of the rotating shaft 70, that is, when the second screw blade 76b is extremely small, substantially only the rotating shaft 70 of the first embodiment is used. Equivalent to what you have. Further, also in the present embodiment, the length of the third region 73 is longer than the length of the second region 72 with respect to the first direction D1.

As described above, according to the developing apparatus 204 of the present embodiment, the length of the third region 73 of the first transport screw 25 is longer than the length of the second region 72 with respect to the first direction D1. As a result, it is possible to suppress the discharge of a non-surplus developer from the developer discharge port 40.

Further, according to the developing apparatus 204 of the present embodiment, a second screw having an outer diameter smaller than the outer diameter of the first screw blade 76a in at least a part of the first region 71, the second region 72, and the third region 73. The blade 76b is formed. Therefore, while ensuring the transportability of the developer, the developer is not significantly flipped up on the downstream side of the developer discharge port 40, and even when the amount of the developer is small, the vicinity of the developer discharge port 40 It is possible to suppress the splashing of the developer in.

<Fourth Embodiment>
A fourth embodiment of the present invention will be described with reference to FIG. In the developing apparatus 304 of the present embodiment, the first transfer screw 25 is formed in that the second screw blade 76b is formed in at least a part of the first region 71, the second region 72, and the third region 73. The configuration is different from that of the second embodiment. However, since the other configurations are the same as those of the second embodiment, the same reference numerals are given and detailed description thereof will be omitted. When the outer diameter of the second screw blade 76b is slightly larger than the outer diameter of the rotating shaft 70, that is, when the second screw blade 76b is extremely small, substantially only the rotating shaft 70 of the second embodiment is used. Equivalent to having.

In the present embodiment, the screw blade (third screw blade) 77 is provided on the downstream side of the third region 73 of the first transport screw 25. Further, in the first transfer screw 25, the first screw blade 76a, which is a rotary shaft 70 screw blade, is formed in the fourth region 74. The outer diameter of the screw blade 77 is larger than the outer diameter of the second screw blade 76b. Therefore, the developer conveyed by the second screw blade 76b is more smoothly conveyed after reaching the screw blade 77.

As described above, according to the developing apparatus 304 of the present embodiment, the first transport screw 25 secures a length of the third region 73 of 10 mm with respect to the first direction D1 and is connected to the developing agent discharge port 40. A sufficient distance from the screw blade 76 provided in the fourth region 74 can be taken. As a result, the screw blade 77 on the downstream side of the developer discharge port 40, which easily flips up the developer, can be sufficiently separated from the developer discharge port 40, and even when the amount of the developer is small, the developer discharge port 40 It is possible to suppress the splashing of the developer in the vicinity.

Further, according to the developing apparatus 304 of the present embodiment, the second screw having an outer diameter smaller than the outer diameter of the first screw blade 76a in at least a part of the first region 71, the second region 72, and the third region 73. The blade 76b is formed. Therefore, while ensuring the transportability of the developer, the developer is not significantly flipped up on the downstream side of the developer discharge port 40, and even when the amount of the developer is small, the vicinity of the developer discharge port 40 It is possible to suppress the splashing of the developer in.

In the developing devices 4a, 104, 204, 304 of the first to fourth embodiments described above, the so-called vertical stirring configuration in which the developing chamber 23 is arranged on the top and the stirring chamber 24 is arranged on the bottom in a vertical row vertically. However, the explanation is not limited to this. The relationship between the developing chamber 23 and the stirring chamber 24 may be in a vertical positional relationship. For example, the developing chamber 23 may be located diagonally above the stirring chamber 24. Alternatively, the developing chamber 23 may be arranged below the stirring chamber 24. Further, the developer discharge port 40 is not limited to being provided in the developing chamber 23, and may be provided in the stirring chamber 24 instead of the developing chamber 23.

4a, 104, 204, 304 ... Development device, 22 ... Development container, 23 ... Development room (first room), 24 ... Stirring room (second room), 25 ... First transport screw, 26 ... Second transport Screw, 27 ... partition wall, 27a ... 1st communication port, 27b ... 2nd communication port, 28 ... development sleeve (developer carrier), 40 ... developer discharge port (developer discharge part), 70 ... rotary shaft, 71 ... 1st region, 72 ... 2nd region, 73 ... 3rd region, 74 ... 4th region, 75 ... 5th region, 76 ... screw blade, 76a ... 1st screw blade, 76b ... 2nd screw blade, 77 ... Screw blade (third screw blade), A1 ... maximum image area, D1 ... first direction, D2 ... second direction.

Claims (11)

The developing container for accommodating the developing agent, which has a first chamber and a second chamber provided above or below the first chamber and forming a circulation path for the developing agent together with the first chamber. With the container
A developer carrier that supports and rotates the developer supplied from the first chamber or the second chamber, and
A first transport screw, which is arranged in the first chamber and transports the developer in the first chamber in the first direction,
A second transport screw, which is arranged in the second chamber and transports the developer in the second chamber in the second direction opposite to the first direction,
Inside the developing container, the first chamber and the second chamber are vertically separated from each other, and the developer is delivered from the second chamber to the first chamber, and the first communication port from the first communication port. A partition wall provided on the downstream side in one direction and having a second communication port for passing the developing agent from the first chamber to the second chamber.
In the first chamber, a surplus developer in the developing container is discharged from the developing container, which is provided between the second communication port and the maximum image region of the developing agent carrier in the first direction. A developing device including a developer discharging unit.
The first chamber is adjacent to the first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction, and the first region to the said. A second region, which is at least a part of the region up to the maximum image region, a third region adjacent to the downstream side of the first region, and a region within a predetermined range from the downstream end of the first region, and the above. It has a fourth region adjacent to the upstream side of the second region and at least partly overlapping the maximum image region.
The first transport screw is provided around a rotation shaft provided at least over the fourth region, the second region, the first region, and the third region, and at least around the rotation shaft in the fourth region. It has a screw blade formed in a spiral shape, and the screw blade is not formed on the rotation axis in the first region, the second region, and the third region.
With respect to the first direction, the length of the third region is longer than the length of the second region.
A developing device characterized by this. With respect to the first direction, the length of the third region is 10 mm or more.
The developing apparatus according to claim 1. The developing container for accommodating the developing agent, which has a first chamber and a second chamber provided above or below the first chamber and forming a circulation path for the developing agent together with the first chamber. With the container
A developer carrier that supports and rotates the developer supplied from the first chamber or the second chamber, and
A first transport screw, which is arranged in the first chamber and transports the developer in the first chamber in the first direction,
A second transport screw, which is arranged in the second chamber and transports the developer in the second chamber in the second direction opposite to the first direction,
Inside the developing container, the first chamber and the second chamber are vertically separated from each other, and the developer is delivered from the second chamber to the first chamber, and the first communication port from the first communication port. A partition wall provided on the downstream side in one direction and having a second communication port for passing the developing agent from the first chamber to the second chamber.
In the first chamber, a surplus developer in the developing container is discharged from the developing container, which is provided between the second communication port and the maximum image region of the developing agent carrier in the first direction. A developing device including a developer discharging unit.
The first chamber is adjacent to the first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction, and the first region to the said. A second region, which is at least a part of the region up to the maximum image region, a third region adjacent to the downstream side of the first region, and a region within a predetermined range from the downstream end of the first region, and the above. It has a fourth region adjacent to the upstream side of the second region and at least partly overlapping the maximum image region.
The first transport screw is provided around a rotation shaft provided at least over the fourth region, the second region, the first region, and the third region, and at least around the rotation shaft in the fourth region. It has a screw blade formed in a spiral shape, and the screw blade is not formed on the rotation axis in the first region, the second region, and the third region.
With respect to the first direction, the length of the third region is 10 mm or more.
A developing device characterized by this. With respect to the first direction, the length of the second region is 10 mm or more.
The developing apparatus according to claim 3. The first transport screw has a spiral screw blade formed on the rotation axis in a fifth region which is a region adjacent to the downstream side of the third region in the first direction.
The developing apparatus according to any one of claims 1 to 4, wherein the developing apparatus is characterized by this. The developing container for accommodating the developing agent, which has a first chamber and a second chamber provided above or below the first chamber and forming a circulation path for the developing agent together with the first chamber. With the container
A developer carrier that supports and rotates the developer supplied from the first chamber or the second chamber, and
A first transport screw, which is arranged in the first chamber and transports the developer in the first chamber in the first direction,
A second transport screw, which is arranged in the second chamber and transports the developer in the second chamber in the second direction opposite to the first direction,
Inside the developing container, the first chamber and the second chamber are vertically separated from each other, and the developer is delivered from the second chamber to the first chamber, and the first communication port from the first communication port. A partition wall provided on the downstream side in one direction and having a second communication port for passing the developing agent from the first chamber to the second chamber.
In the first chamber, a surplus developer in the developing container is discharged from the developing container, which is provided between the second communication port and the maximum image region of the developing agent carrier in the first direction. A developing device including a developer discharging unit.
The first chamber is adjacent to the first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction, and the first region to the said. A second region, which is at least a part of the region up to the maximum image region, a third region adjacent to the downstream side of the first region, and a region within a predetermined range from the downstream end of the first region, and the above. It has a fourth region adjacent to the upstream side of the second region and at least partly overlapping the maximum image region.
The first transport screw is provided around a rotation shaft provided at least over the fourth region, the second region, the first region, and the third region, and at least around the rotation shaft in the fourth region. The spirally formed first screw blade and the first screw blade spirally formed around the rotation axis in at least a part of the first region, the second region, and the third region. It has a second screw blade with an outer diameter smaller than the outer diameter,
With respect to the first direction, the length of the third region is longer than the length of the second region.
A developing device characterized by this. With respect to the first direction, the length of the third region is 10 mm or more.
The developing apparatus according to claim 6. The developing container for accommodating the developing agent, which has a first chamber and a second chamber provided above or below the first chamber and forming a circulation path for the developing agent together with the first chamber. With the container
A developer carrier that supports and rotates the developer supplied from the first chamber or the second chamber, and
A first transport screw, which is arranged in the first chamber and transports the developer in the first chamber in the first direction,
A second transport screw, which is arranged in the second chamber and transports the developer in the second chamber in the second direction opposite to the first direction,
Inside the developing container, the first chamber and the second chamber are vertically separated from each other, and the developer is delivered from the second chamber to the first chamber, and the first communication port from the first communication port. A partition wall provided on the downstream side in one direction and having a second communication port for passing the developing agent from the first chamber to the second chamber.
In the first chamber, a surplus developer in the developing container is discharged from the developing container, which is provided between the second communication port and the maximum image region of the developing agent carrier in the first direction. A developing device including a developer discharging unit.
The first chamber is adjacent to the first region, which is a region from the upstream end to the downstream end of the developer discharging portion, and the upstream side of the first region in the first direction, and the first region to the said. A second region, which is at least a part of the region up to the maximum image region, a third region adjacent to the downstream side of the first region, and a region within a predetermined range from the downstream end of the first region, and the above. It has a fourth region adjacent to the upstream side of the second region and at least partly overlapping the maximum image region.
The first transport screw is provided around a rotation shaft provided at least over the fourth region, the second region, the first region, and the third region, and at least around the rotation shaft in the fourth region. The spirally formed first screw blade and the first screw blade spirally formed around the rotation axis in at least a part of the first region, the second region, and the third region. It has a second screw blade with an outer diameter smaller than the outer diameter,
With respect to the first direction, the length of the third region is 10 mm or more.
A developing device characterized by this. With respect to the first direction, the length of the second region is 10 mm or more.
The developing apparatus according to claim 8. The first transport screw has a third screw blade spirally formed around the rotation axis in a fifth region which is a region adjacent to the downstream side of the third region in the first direction. ,
The outer diameter of the third screw blade is larger than the outer diameter of the second screw blade.
The developing apparatus according to any one of claims 6 to 9, wherein the developing apparatus is characterized by this. The first chamber is provided above the second chamber, and a developer is supplied to the developer carrier.
The second chamber collects the developer from the developer carrier.
The developing apparatus according to any one of claims 1 to 10.

Images