JP5472909B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a stirring and supplying mechanism for replenishing toner and developer in a two-component developing device in the electrophotographic field.

  A conventional two-component developing device using a mixture of toner and carrier as a developer is configured as shown in FIG. The developing device includes a developing roller 15 that supplies toner to develop the electrostatic latent image formed on the photoconductor 10, a first mixing and agitating unit 14 that supplies developer to the developing roller 15, The developer conveyed from the mixing and agitating unit 14 and the replenishment toner supplied from the replenishing port 22 from the toner replenishing device (not shown) through the replenishment path 20 are mixed and agitated, so that the first mixing and agitating unit 14 And a second mixing and agitation unit 16 that conveys to

  In addition, on the periphery of the photoconductor 10, a charging roller 12 that charges the periphery of the photoconductor 10, an exposure device 13 that exposes the periphery of the charged photoconductor 10, and the photoconductor 10 developed by the developing roller 15. After the toner image is transferred to the transfer belt 30, a cleaning blade 17 is provided to remove the remaining toner on the photoconductor 10. Further, the transfer roller 40 is disposed to face the photoconductor 10 through the transfer belt 30.

  In the developing area where the photoconductor 10 and the developing roller 15 face each other, only the toner is consumed and the carrier is reused. In order to replenish the toner consumed in the development area, the developing device predicts the amount of toner used for printing in advance by measuring the bit count or the like, or measuring the density with a toner density sensor, so Is supplied from the toner replenishing device.

  In recent years, MFPs, printers, and the like have been digitized, and apparatuses that form images with digital exposure apparatuses such as laser scanners and LED heads have become mainstream. Therefore, the amount of toner consumed over time can be predicted by grasping and calculating the drawing amount as a digital value. However, the actual toner consumption varies depending on the usage environment and the usage state of the electrophotographic member. The toner replenishing device is also a mechanical component, and since the replenishment amount changes, it is necessary to check the amount of toner supplied by a toner density sensor or the like. The toner concentration sensor measures the density of carriers near the sensor using a magnetic permeability sensor. Actually, the carrier concentration is measured instead of the toner density.

  In addition, the toner replenishing device is configured such that a replenishing roller of a shaft with a cut groove or a groove is passed through a narrow gap in order to quantitatively replenish toner. The replenishing toner supplied from the toner replenishing device is put into the developer in the developing device in a state where the secondary particles or more are aggregated. This is due to the fact that the toners are rubbed in the toner tank and are charged to opposite polarities or agglomerated by being left standing or by pressure. The charged toner particle group comes into contact with the carrier surface of the developer and is charged to adhere to the surface of the carrier. In this process, each toner is properly charged and carried on the carrier surface. The charged toner particle group is in a developable state only in this state.

  In recent years, there has been a tendency to reduce the amount of developer by downsizing the apparatus. In particular, the image density can be maintained even with a small amount of developer by increasing the pigment of the toner and reducing the particle size of the carrier because of high image quality and low cost.

  However, in the two-component developing device, it is necessary to accurately measure the consumed toner, put it in a carrier, stir and charge and disperse it. This requires stirring time. When the stirring time is short, the toner is not sufficiently charged, and is transported to the development area in a state where it is not carried on the carrier surface. In order to lengthen the developer stirring time, it is proposed to provide a sub-mixing stirring unit that further mixes and stirs the developer in addition to the main stirring and conveying unit that supplies the developer to the developing roller. (For example, Patent Document 1).

JP-A-9-325612

  However, in the above-mentioned Patent Document 1, there is a problem that the apparatus size becomes large because a main stirring and conveying unit and a separate sub-mixing stirring unit are provided. In addition, the developer is a mixture of a powder carrier whose surface is coated with a resin such as ferrite or magnetite, and a toner containing a resin as a main component. Therefore, when the toner is mixed in the developer flow, there is a difference in specific gravity with the developer already present in the developing device. Therefore, as shown in FIG. 10, the replenished toner Tadd supplied from the toner replenishing device. Is not entrained in the developer D and is transported to the development area with insufficient charging and dispersion. Therefore, there are problems that image B / G increase, image contamination, and in-machine contamination occur. In particular, in the case of an A4 size high-speed developing device, the agitation time is about 25% shorter than that of an A3 size developing device.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved apparatus that can efficiently supply replenishment toner into a developer and impart charging. Another object of the present invention is to provide a developing device and an image forming apparatus.

  In order to solve the above-described problems, according to one aspect of the present invention, a developer comprising a carrier and a toner is provided on a peripheral surface and is provided opposite to an electrostatic latent image carrier that carries an electrostatic latent image. A developer carrier that is supplied to the electrostatic latent image carrier, a first agitation transport unit that is provided opposite to the developer carrier, and that supplies the developer to the developer carrier, and a first agitation transport A second agitating / conveying unit that conveys the developer and replenishment toner conveyed from the unit to the first agitating / conveying unit while mixing and agitating, and a second agitating unit from the first agitating / conveying unit. A sub-stirring conveyance unit that is provided in a conveyance path toward the conveyance unit and that mixes and stirs the developer and replenishment toner conveyed from the first agitation conveyance unit, and the sub-agitation conveyance unit includes the first agitation conveyance unit A vertical transport unit that transports the developer transported from the top vertically, and lead that has been introduced from above There is provided a developing device comprising: an agitation unit that agitates developer and replenishment toner conveyed by the conveyance unit and communicates with the second agitation conveyance unit through a through-hole formed below. The

  Here, the developer conveyance capacity increases in the order of the first agitation conveyance unit, the vertical conveyance unit, and the agitation unit, and the agitation unit and the second agitation conveyance unit are configured to have substantially the same conveyance capability. The

  In addition, a toner replenishment unit that supplies replenishment toner may be provided above the agitation unit.

  Further, a toner concentration detection unit for detecting the toner concentration is provided in the conveyance path of the first agitation conveyance unit, and replenishment toner is supplied from the toner replenishment unit based on the detection result by the toner concentration detection unit. Also good.

  Alternatively, a consumed toner amount estimation unit that estimates an amount of consumed toner consumed by the electrostatic latent image carrier based on an exposure area and / or exposure intensity for exposing the electrostatic latent image on the electrostatic latent image carrier. A toner concentration detection unit for detecting the toner density in the conveyance path of the second agitation conveyance unit, and the toner replenishment unit is a toner of the developer in the second agitation conveyance unit by the toner concentration detection unit The replenishment toner amount may be determined based on the density detection result and the estimation result by the consumed toner amount estimation unit.

  Furthermore, the vertical conveyance part and stirring part which comprise a substirring conveyance part can also be arrange | positioned substantially in parallel.

  Moreover, the vertical conveyance part and stirring part which comprise a substirring conveyance part can also be arrange | positioned concentrically.

  In order to solve the above problems, according to another aspect of the present invention, an electrostatic latent image carrier that carries an electrostatic latent image on a peripheral surface, and an electrostatic latent image on the electrostatic latent image carrier. A developing device for developing the toner, and the developing device is provided to face the electrostatic latent image carrier, carries a developer composed of a carrier and toner on the peripheral surface, and supplies the developer to the electrostatic latent image carrier. A developer carrier, a first agitation transport unit that is provided opposite to the developer carrier and supplies the developer to the developer carrier, and the developer and replenishment toner that are transported from the first agitation transport unit A second agitating and conveying unit that conveys the mixture to the first agitating and conveying unit while mixing and agitating, and provided in a conveying path from the first agitating and conveying unit to the second agitating and conveying unit, A sub-stirring and transporting unit that mixes and stirs the developer transported from the first stirring and transporting unit and the replenishment toner. Agitates the developer and replenishment toner carried by the vertical conveyance unit, which is supplied from above, and forms the lower part. The vertical conveyance unit conveys the developer conveyed from the first agitation conveyance unit vertically upward. An image forming apparatus is provided, comprising: a stirring unit that communicates with the second stirring and conveying unit through the formed through hole.

  As described above, according to the present invention, it is possible to provide a developing device and an image forming apparatus capable of efficiently supplying replenishment toner into a developer and charging it.

1 is an explanatory diagram showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic plan view showing a schematic configuration of a developing unit according to the same embodiment. FIG. 3 is a side view of FIG. 2. It is a schematic perspective view which shows the structure of the sub stirring conveyance part which concerns on the same embodiment. FIG. 6 is an explanatory diagram illustrating a mixed state of replenishment toner and developer in a sub-stirring conveyance unit. It is the schematic plan view and schematic side view which show the structure of the sub stirring conveyance part which concerns on the 2nd Embodiment of this invention. It is a schematic perspective view which shows the structure of the sub stirring conveyance part which concerns on the same embodiment. It is a schematic perspective view which shows the modification of the sub stirring conveyance part which concerns on the same embodiment. The schematic structure of the conventional developing device is shown, the upper figure is a partial schematic plan view, and the lower figure is a schematic side view. It is explanatory drawing which shows the mixing state of the conventional replenishment toner and developer.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. First Embodiment>
[Configuration of Image Forming Apparatus]
First, a schematic configuration of an image forming apparatus 100 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory diagram illustrating a schematic configuration of the image forming apparatus 100 according to the present embodiment.

  The image forming apparatus 100 according to the present embodiment is a laser printer, a copier, a facsimile, or the like, for example. As an example of the image forming apparatus 100, in FIG. 1, a toner image primarily transferred onto a transfer belt 130 suspended by four rollers 132a, 132b, 132c, and 132d is secondarily transferred onto a sheet P to form an image. 1 shows an image forming apparatus 100 of an obtained type. The image forming apparatus 100 includes a paper supply unit 110, an image forming unit 120, and a fixing unit 160.

  The paper supply unit 110 is a unit that stacks paper P onto which a toner image formed by an image forming unit 120 described later is transferred and outputs the paper P to the transfer roller 150.

  The image forming unit 120 is a unit that forms a toner image to be transferred onto the paper P. For example, four image forming units 120BK, 120C, 120M, and 4M are formed to form toner images of four colors (black, cyan, magenta, and yellow). 120Y. The image forming units 120BK, 120C, 120M, and 120Y have the same configuration.

  For example, the image forming unit 120Y will be described. The photosensitive member 121Y on which an electrostatic latent image is formed, the charging roller 122Y that charges the peripheral surface of the photosensitive member 121Y, and the peripheral surface of the charged photosensitive member 121Y are exposed. And an exposure device 123Y for forming an electrostatic latent image. Further, the image forming unit 120Y attaches the toner supplied from the stirrers 124Y and 126Y that stirs the toner as the developer to the electrostatic latent image formed on the photoreceptor 121Y to the toner image. And a cleaning blade 127Y that removes the toner remaining on the photoreceptor 121Y after the toner image is transferred to the transfer belt 130.

  Further, transfer rollers 140BK, 140C, 140M, and 140Y for transferring the toner image to the transfer belt 130 are disposed to face the photoconductors 121BK, 121C, 121M, and 121Y with the transfer belt 130 interposed therebetween.

  The developer and the replenishment toner supplied from the toner replenishing device 180 via the replenishment path 182 are efficiently mixed and agitated between the agitators 124 and 126 of the image forming unit 120 according to the present embodiment. A sub-stirring conveyance unit 170 is provided. A detailed configuration of the sub-stirring conveyance unit 170 will be described later.

  The image forming apparatus 100 generates a toner image of each color by the image forming unit 120 in accordance with the image data, and sequentially transfers the toner image onto the transfer belt 130 that is an intermediate transfer member, thereby generating a full color toner image. The full-color toner image is collectively transferred onto the paper P transported from the paper supply unit 110 by the secondary transfer unit constituted by the transfer roller 150 and the roller 132a. The sheet P on which the full color toner image is transferred is conveyed to the fixing unit 160. A full color toner image is fixed on the paper P conveyed to the fixing unit 160 by means of heat, pressure, or the like by rollers 162 and 164. On the other hand, the transfer belt 130 transfers the full color toner image onto the paper P at the secondary transfer portion, and then the toner remaining on the transfer belt 130 is removed by a cleaner (not shown).

  The configuration of the image forming apparatus 100 according to the present embodiment has been described above. In the image forming apparatus 100 according to the present embodiment, a sub-stirring conveyance unit 170 that supplies toner is provided between the stirrers 124 and 126 of the developing unit that develops the electrostatic latent image formed on the photosensitive member 121, thereby supplying the toner. The replenishment toner supplied from the apparatus and the developer flowing through the stirrers 124 and 126 can be efficiently mixed and stirred. The configuration of the developing unit according to this embodiment will be described below with reference to FIGS. FIG. 2 is a schematic plan view showing a schematic configuration of the developing unit according to the present embodiment. FIG. 3 is a side view of FIG. FIG. 4 is a schematic perspective view illustrating a configuration of the sub-stirring conveyance unit according to the present embodiment. FIG. 5 is an explanatory diagram showing a mixed state of the replenishment toner and the developer in the sub-stirring conveyance unit.

[Configuration of development unit and sub-stirring transport unit]
As shown in FIGS. 2 and 3, the developing unit according to the present embodiment includes a developing roller 125 that conveys toner and supplies the toner to the photosensitive member 121 in a developing region facing the photosensitive member 121. The developing roller 125 is a magnet roller having a fixed magnet inside, and a nonmagnetic sleeve carrying a developer on its surface, which is rotatable. The developing unit also includes a first stirrer 124 that supplies the developer mixed and stirred to the developing roller 125, the developer conveyed from the first stirrer 124, and the replenishment toner supplied from the toner replenishing device. And a second stirrer 126 that conveys the mixture to the first stirrer 124. Each of the transport paths of the first stirrer 124 and the second stirrer 126 is provided with a screw as a transport blade on the support shaft, and the developer is transported by rotating the screw. The developing unit according to this embodiment includes a sub-stirring conveyance unit 170 between the conveyance paths through which the developer is conveyed from the first agitator 124 to the second agitator 126.

  As shown in FIG. 4, the sub-stirring conveyance unit 170 includes a vertical conveyance unit 171 that conveys the developer conveyed from the first agitator 124 vertically upward, and a developer and toner conveyed by the vertical conveyance path 171. A stirring unit 174 that mixes and stirs the replenishing toner supplied from the replenishing device and discharges it to the second stirrer 126.

  As shown in FIGS. 3 and 4, the vertical conveyance unit 171 is a cylindrical member extending in the z-axis direction, and the y-axis negative direction end of the first stirrer 124 extending in the horizontal direction (y-axis direction). The upper part is provided in communication with the developer conveyance path of the first stirrer 124. A screw 172 for conveying the developer vertically upward is provided inside the vertical conveyance unit 171. A through-hole 171 a is formed above the outer peripheral surface of the vertical transport unit 171, and the internal space of the vertical transport unit 171 and the internal space of the stirring unit 174 are connected by a connecting unit 173.

  The communication unit 173 is an internal member that connects the internal space of the vertical conveyance unit 171 and the internal space of the stirring unit 174 in a substantially horizontal direction (a direction substantially orthogonal to the z-axis direction). At this time, the z-axis negative direction side surface 173a of the communication part 173 may be inclined in the z-axis negative direction from the vertical transport part 171 side toward the first stirring chamber 174a. As a result, the developer conveyed upward by the vertical conveyance unit 171 can be easily moved to the first stirring chamber 174a.

  The stirring unit 174 includes a first stirring chamber 174a and a second stirring chamber 174b. The first stirring chamber 174a and the second stirring chamber 174b are respectively cylindrical members extending in the z-axis direction, and are arranged side by side in the x-axis direction so as to intersect. The interior of the first stirring chamber 174a and the second stirring chamber 174b intersect with each other, and the developer can move inside each of the stirring chambers 174a and 174b.

  In the first stirring chamber 174a and the second stirring chamber 174b, stirring members 175a and 175b for stirring the developer and the toner are provided, respectively. The stirring members 175a and 175b can be configured, for example, by arranging plate-like paddles 175c in the axial direction at a predetermined angular interval (for example, 90 °) on a rotating shaft extending in the z-axis direction. By rotating the rotating shaft, the developer and toner inside the stirring unit 174 can be stirred by the paddle 175c.

  A through hole is formed above the outer peripheral surface of the first stirring chamber 174a, and the internal space of the first stirring chamber 174a is communicated with the internal space of the vertical transfer unit 171 by a connecting portion 173. Further, an opening is formed on the upper surface of the first stirring chamber 174a, and the replenishment path 182 through which replenished toner is conveyed from the toner replenishing device (reference numeral 180 in FIG. 1) communicates with the inside of the agitating chamber 174. . Thereby, the replenishment toner is supplied from the toner replenishing device via the replenishment path 182 from above the first stirring chamber 174a. On the other hand, a through hole 176 for communicating with the conveyance path of the second stirrer 126 is formed in the bottom surface of the second stirring chamber 174b.

  Such a sub-stirring transport unit 170 transports the developer transported from the first stirrer 124 vertically upward by the screw 172 of the vertical transport unit 171, and then from the through-hole 171 a via the communication unit 173. The developer is dropped into the internal space of the first stirring chamber 174a from the through hole of the first stirring chamber 174a. On the other hand, the replenishment toner supplied from the toner replenishing device via the replenishment path 182 is dropped from above the first agitation chamber 174a into the internal space of the first agitation chamber 174a. Then, the developer and the replenishing toner are stirred by the stirring members 175a and 175b provided inside the first stirring chamber 174a and the second stirring chamber 174b. The stirred developer and replenishment toner fall into the transport path of the second stirrer 126 through a through hole 176 formed in the bottom surface of the second stirring chamber 174b.

  That is, in the sub-stirring conveyance unit 170 of the present embodiment, the toner is sufficiently mixed and stirred using the gravity moving force of the developer as compared with the conventional toner replenishing device, and the main stirring unit (first stirring unit) is used. And the second stirrer 126). Therefore, even if the main stirrer is designed around the function of supplying the developer to the developing roller 125 and the layer regulating member, the toner can be dispersed on the carrier surface even if the main stirrer is increased in speed and capacity. In addition, an appropriate charge amount can be maintained. In particular, if the height in the vertical direction (z-axis direction) of the sub-stirring conveyance unit 170 is secured about 50 to 70 mm, the developer capacity for one axis of the conventional mixing and stirring device can be secured, and the development area Miniaturization can be realized.

  Further, in the image forming apparatus 100 shown in FIG. 1, the vertical space of the annular transfer belt 130 is a dead space, and the sub-stirring conveyance unit 170 is provided for the width w without increasing the apparatus size. be able to. Further, the length of the stirring unit 174 in the x-axis direction is determined from the length in the x-axis direction from the first stirrer 124 to the second stirrer 126 to the x from the developing roller 125 to the second stirrer 126. By making it fit within the length in the axial direction, the sub-stirring conveyance unit 170 can be provided with almost no change in the apparatus size.

  Here, in order not to retain the flow of the developer from the first stirrer 124 to the vertical transport unit 171, the stirrer 174, and the second stirrer 126, the transport capability of the developer in each unit is It is comprised so that it may become large in order of the stirrer 124, the vertical conveyance part 171, and the stirring part 174. FIG. Moreover, the conveyance capability of the stirring part 174 and the 2nd stirrer 126 is comprised so that it may become substantially the same.

  In the sub-stirring conveyance unit 170 according to this embodiment, the toner replenishing unit is provided above the first stirring chamber 174a. For this reason, as shown in FIG. 5, the developer D conveyed by the vertical conveyance unit 171 and the replenishment toner Tadd supplied from the toner replenishment unit may be put into the stirring unit 174 so as to be stacked. it can. Therefore, separation due to the difference in specific gravity between the replenishment toner Tadd and the developer D can be forcibly mixed and effectively agitated by the agitating members 175a and 175b of the agitating unit 174. It can be dispersed efficiently and charged.

  Here, the amount of replenished toner supplied from the toner replenishing device is, for example, the detection result of the toner density sensor 191 (see FIG. 2) provided on the downstream side in the developer transport direction of the transport path of the first stirrer 124. Can be determined. The toner concentration sensor 191 can detect the toner concentration in the developer after the toner is consumed for developing the electrostatic latent image. Therefore, the replenishing toner is supplied from the toner replenishing device so that the toner amount detected by the toner concentration sensor 191 becomes the amount of toner to be included in the developer.

  Alternatively, the replenishment toner amount supplied from the toner replenishing device based on the detection result of the toner density sensor 192 (see FIG. 2) provided on the downstream side in the developer transport direction of the transport path of the second stirrer 126. May be determined. The consumed toner amount used for developing the electrostatic latent image can be estimated by a consumed toner amount estimation unit (not shown) based on the exposure area and / or the exposure intensity of the exposure apparatus. The toner amount supplied by the toner replenishing device may be substantially the same as the consumed toner amount estimated by the consumed toner amount estimation unit. However, as described above, the estimated consumed toner amount and actual The amount of consumed toner may be different. In view of this, it is possible to correct the consumed toner amount estimated by the consumed toner amount estimation unit based on the toner concentration detected by the toner concentration sensor 192 so as to supply the replenishment toner more accurately.

  The configuration of the sub-stirring conveyance unit 170 provided in the developing unit according to the present embodiment and the operation due to this have been described above. By providing such a sub-stirring conveyance unit 170, the replenishment toner can be efficiently dispersed in the developer and charged. As a result, the image forming apparatus 100 can be speeded up and downsized.

<2. Second Embodiment>
Next, based on FIG. 6 and FIG. 7, the structure of the substirring conveyance part 270 which concerns on 2nd Embodiment is demonstrated. The sub-stirring conveyance unit 270 according to this embodiment can be provided in place of the sub-stirring conveyance unit 170 in the developing unit of the image forming apparatus 100 described in the first embodiment. Below, the structure and effect | action of the sub stirring conveyance part 270 which concern on this embodiment are demonstrated in detail. FIG. 6 is a schematic plan view and a schematic side view showing the configuration of the auxiliary stirring and conveying unit 270 according to the present embodiment. FIG. 7 is a schematic perspective view illustrating the configuration of the sub-stirring conveyance unit 270 according to the present embodiment.

  Similarly to the sub-stirring and transporting unit 170 of the first embodiment, the sub-stirring and transporting unit 270 according to the present embodiment transports the developer from the first stirrer 124 to the second stirrer 126 as shown in FIG. Provided between the transport paths. The sub-stirring transport unit 270 is a vertical transport unit 271 that transports the developer transported from the first stirrer 124 vertically upward, and the replenishment supplied from the developer transported by the vertical transport path 271 and the toner replenishing device. A stirring unit 274 that mixes and stirs the toner and discharges the toner to the second stirrer 126.

  The vertical conveyance unit 271 is a cylindrical member extending in the z-axis direction, like the vertical conveyance unit 171 according to the first embodiment, and the y-axis of the first stirrer 124 extending in the horizontal direction (y-axis direction). Above the negative end, the first stirrer 124 is provided in communication with the developer conveyance path. A screw 272 for transporting the developer vertically upward is provided inside the vertical transport unit 271. A through-hole 271 a is formed above the outer peripheral surface of the vertical transport unit 271, and the internal space of the vertical transport 271 and the internal space of the stirring unit 274 are connected by a connecting unit 273.

  The stirring unit 274 is a cylindrical member extending in the z-axis direction, and a stirring member 275 that stirs the developer and toner is provided therein. As shown in FIG. 7, the stirring member 275 according to the present embodiment is configured by disposing plate-like members 275a so as to extend vertically downward from four support portions extending in the radial direction from the rotation shaft. By rotating the rotation shaft, the four plate-like members 275a also rotate around the rotation shaft, and the developer and the replenishment toner charged into the stirring unit 174 can be stirred.

  A through hole is formed above the outer peripheral surface of the agitating unit 274, and the internal space of the agitating unit 274 is communicated with the internal space of the vertical conveying unit 271 by the connecting unit 273. In addition, an opening 274 c is formed on the upper surface of the agitation unit 274 for communicating the replenishment path 182 of the toner replenishing device with the internal space of the agitation unit 274. As a result, toner is supplied from the toner replenishing device from above the stirring unit 274. A through hole 276 for communicating with the conveyance path of the second stirrer 126 is formed on the bottom surface of the stirring unit 274.

  Such a sub-stirring transport unit 270 transports the developer transported from the first stirrer 124 vertically upward by the screw 272 of the vertical transport unit 271, and then stirs from the through hole 271 a via the communication unit 273. The developer is dropped from the through hole of the part 274 into the internal space of the stirring part 274. On the other hand, the replenishment toner supplied from the toner replenishing device is dropped from above the stirring unit 274 into the internal space of the stirring unit 274. Then, the developer and the replenishment toner are agitated by the agitating member 275 provided inside the agitating unit 274. The stirred developer and replenishment toner fall to the transport path of the second stirrer 126 through a through hole 276 formed in the bottom surface of the stirring unit 274.

  The sub-stirring and conveying unit 270 according to the present embodiment also uses the developer's gravitational force to sufficiently mix and stir the toner to the main stirring unit (first stirrer 124 and second stirrer 126). Can be supplied. In addition, since the toner replenishing unit is provided above the agitating unit 274, the developer conveyed by the vertical conveying unit 271 and the replenishing toner supplied from the toner replenishing unit are stacked so as to be stacked. Can be put in. Therefore, the separation due to the difference in specific gravity between the replenishment toner and the developer can be forcibly mixed and effectively agitated by the agitating member 275 of the agitating unit 274, so that the replenishment toner can be efficiently dispersed in the developer, In addition, charging can be imparted.

  Heretofore, the configuration of the sub-stirring conveyance unit 270 provided in the developing unit according to the present embodiment and the operation due to this have been described. By providing such a sub-stirring conveyance unit 270, the replenishment toner can be efficiently dispersed in the developer and charged. As a result, the image forming apparatus 100 can be speeded up and downsized.

  A modification of the sub-stirring conveyance unit 270 according to this embodiment is shown in FIG. The sub-stirring conveyance unit 370 is provided inside a stirring unit 374 in which a vertical conveyance unit 371 that conveys the developer conveyed from the first stirrer 124 vertically upward mixes and stirs the developer and the replenishment toner. It is the composition which was made. In addition, a plate-like member that is provided inside the vertical conveyance unit 371 and that mixes and stirs the developer and supply toner supplied to the agitation unit 374 to a rotating shaft 373 of the screw 372 for conveying the developer vertically upward. A stirring blade is provided. Thereby, a screw and a stirring blade can be rotated by one axis | shaft.

  When the developer conveyed from the first stirrer 124 is conveyed vertically upward by the screw 372 of the vertical conveying unit 371, the sub-stirring conveying unit 370 overflows the developer from the upper end of the vertical conveying unit 371, and The developer is dropped into the stirring space formed by the outer peripheral surface of the transport unit 371 and the inner peripheral surface of the stirring unit 374. On the other hand, replenished toner is dropped from a toner replenishing device provided above the stirring space. Then, the developer and the replenishing toner are stirred by the stirring member 375 provided in the stirring space of the stirring unit 374. The stirred developer and replenishment toner fall to the transport path of the second stirring unit 126 through a through hole 376 formed in the bottom surface of the stirring unit 374.

  Also in this case, it is possible to supply the main stirrer (the first stirrer 124 and the second stirrer 126) after sufficiently mixing and stirring the toner by utilizing the gravity moving force of the developer. In addition, since the toner replenishing unit is provided above the agitation unit 374, the developer conveyed by the vertical conveyance unit 371 and the replenishment toner supplied from the toner replenishment unit are stacked so as to be stacked. Can be put in. Therefore, the separation due to the specific gravity difference between the replenishment toner and the developer can be forcibly mixed and effectively agitated by the agitating member 375 of the agitating unit 374, so that the replenishment toner is efficiently dispersed in the developer, In addition, charging can be imparted.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above embodiment, the shape of the stirring members 175a, 175b, 275, and 375 is a configuration in which a plurality of paddles are provided on the rotation shaft or a plate-like member that extends vertically downward from above is provided. The present invention is not limited to such an example, and any member that can stir the developer and the replenishment toner introduced into the stirring unit may be used.

  Moreover, in the said embodiment, although the shape of the vertical conveyance parts 171, 271, 371 and the stirring parts 174, 274, 374 was a cylindrical shape, this invention is not limited to this example, an empty prism member, etc. Any shape that can convey the developer may be used.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 120 Image forming unit 121 Photoconductor 124 1st stirrer 125 Developing roller 126 2nd stirrer 170,270,370 Substirring conveyance part 171,271,371 Vertical conveyance part 172,272,372 Screw 173 273 Connecting portion 174, 274, 374 Stirring portion 175a, 175b, 275, 375 Stirring member 176, 276, 376 Through hole 373 Rotating shaft

Claims (8)

A developer carrying body provided opposite to an electrostatic latent image carrying body carrying an electrostatic latent image, carrying a developer composed of a carrier and toner on a peripheral surface and supplying the developer to the electrostatic latent image carrying body;
A first agitating / conveying portion that is provided opposite to the developer carrying member and supplies the developer to the developer carrying member, and the developer conveyed from the first agitating / conveying portion and the replenishment toner are mixed and stirred. A second agitating and conveying unit that conveys to the first agitating and conveying unit,
A sub-stirring conveyance unit that is provided in a conveyance path from the first agitation conveyance unit to the second agitation conveyance unit, and that mixes and agitates the developer conveyed from the first agitation conveyance unit and replenishment toner;
With
The sub-stirring conveyance unit is
A vertical transport unit that transports the developer transported from the first stirring transport unit vertically upward;
An agitation unit that agitates the developer and the replenishment toner that are input from above and that is conveyed by the vertical conveyance unit and communicates with the second agitation conveyance unit at a through hole formed below;
A developing device comprising: The developer transport capability increases in the order of the first stirring transport unit, the vertical transport unit, and the stirring unit.
The developing device according to claim 1, wherein the agitating unit and the second agitating and conveying unit have substantially the same conveyance capability.   The developing device according to claim 1, wherein a toner replenishing unit that supplies replenishing toner is provided above the stirring unit. A toner concentration detection unit configured to detect a toner concentration in the conveyance path of the first agitation conveyance unit;
The developing device according to claim 3, wherein replenished toner is supplied from the toner replenishing unit based on a detection result by the toner density detecting unit. A consumed toner amount estimating unit for estimating a consumed toner amount consumed by the electrostatic latent image carrier based on an exposure area and / or exposure intensity for exposing the electrostatic latent image on the electrostatic latent image carrier; ,
A toner concentration detection unit for detecting a toner concentration in a conveyance path of the second agitation conveyance unit;
With
The toner replenishing unit determines a replenishing toner amount based on a detection result of the toner concentration of the developer in the second stirring and conveying unit by the toner concentration detecting unit and an estimation result by the consumed toner amount estimating unit. The developing device according to claim 3, wherein:   The developing device according to claim 1, wherein the vertical conveyance unit and the agitation unit constituting the sub agitation conveyance unit are arranged substantially in parallel.   The developing device according to claim 1, wherein the vertical conveyance unit and the agitation unit constituting the sub agitation conveyance unit are arranged concentrically. An electrostatic latent image carrier that carries an electrostatic latent image on a peripheral surface;
A developing device for developing the electrostatic latent image on the electrostatic latent image carrier;
With
The developing device includes:
A developer carrying body provided opposite to the electrostatic latent image carrying body, carrying a developer composed of a carrier and toner on a peripheral surface and supplying the developer to the electrostatic latent image carrying body;
A first agitating / conveying portion that is provided opposite to the developer carrying member and supplies the developer to the developer carrying member, and the developer conveyed from the first agitating / conveying portion and the replenishment toner are mixed and stirred. A second agitating and conveying unit that conveys to the first agitating and conveying unit,
A sub-stirring conveyance unit that is provided in a conveyance path from the first agitation conveyance unit to the second agitation conveyance unit, and that mixes and agitates the developer conveyed from the first agitation conveyance unit and replenishment toner;
With
The sub-stirring conveyance unit is
A vertical transport unit that transports the developer transported from the first stirring transport unit vertically upward;
An agitation unit that agitates the developer and the replenishment toner that are input from above and that is conveyed by the vertical conveyance unit and communicates with the second agitation conveyance unit at a through hole formed below;
An image forming apparatus comprising:

Images