JP5742003B2 - Developing device, and process cartridge and image forming apparatus including the same - Google Patents

Description

  The present invention relates to a developing device using a two-component developer including toner and a carrier, and a process cartridge and an image forming apparatus provided with the developing device.

  Conventionally, supply / recovery provided with a supply conveyance path for supplying the developer to the developer carrier and a collection conveyance path for collecting the developed developer on the surface of the developer carrier that has consumed toner in the development region A separation-type developing device is known (for example, Patent Document 1). In the developing device of Patent Document 1, a recovery conveyance path is arranged in parallel below a supply conveyance path that extends in the direction of the rotation axis of the developer carrier along the developer carrier. The downstream side of the supply conveyance path and the upstream side of the collection conveyance path communicate with each other through an opening, and the upstream side of the supply conveyance path and the downstream side of the collection conveyance path communicate with each other through an opening, and a developer Circulates. The developer that has been supplied from the supply conveyance path and has passed through the development area and has a reduced toner concentration is not returned to the supply conveyance path, but is collected in the collection conveyance path and is sufficiently stirred with new toner again. ) Will not return. Therefore, the toner density fluctuation on the developer carrying member can be reduced.

  In the above-described supply / recovery separation type developing device, the developer is transported to the downstream end while recovering the developer from the developer carrier disposed along the recovery transport path in the recovery transport path. Therefore, the amount of developer flowing in the collection conveyance path increases toward the downstream side. In addition, since the supply conveyance path is located above the collection conveyance path, it is necessary to lift and transfer the developer against the weight of the developer at the downstream end of the collection conveyance path. For this reason, the developer conveyance speed drops significantly at the downstream end of the collection conveyance path, and the developer stays at the downstream end of the collection conveyance path. When the developer stays at the downstream end of the recovery transport path, the staying developer staying at the downstream end of the recovery transport path faces the downstream portion of the developer carrying body recovery transport path. In other words, the developed developer on the surface of the developer carrying member closes the space to be collected in the collection conveyance path. As a result, there is a problem that the developed developer at a location facing the downstream side of the developer carrying path of the developer carrying member is not collected to the collection carrying path and is transported again to the development area (hereinafter referred to as developer accompanying). Occur. Since the toner density of the developed developer has decreased, if the developer that has been developed is transported to the development area again due to the rotation of the developer, the density of the image at that portion will decrease, and image unevenness will occur. Will occur.

  Therefore, by increasing the cross-sectional area of the opening that communicates the upstream side of the supply conveyance path and the downstream side of the collection conveyance path, and increasing the amount of developer conveyed from the collection conveyance path to the supply conveyance path, the collection conveyance path It is conceivable to reduce the amount of developer staying downstream. However, as shown in the experiment described later, if the cross-sectional area of the opening is increased to reduce the amount of developer staying downstream in the collection conveyance path, the toner in the developer conveyance path is reduced to the charge amount necessary for development. It has been found that the time until charging becomes longer. This is because, as shown in an experiment described later, when the cross-sectional area of the opening is increased to reduce the amount of staying developer downstream of the recovery conveyance path, the pressure density applied to the developer on the downstream side of the recovery conveyance path is reduced. . As a result, the number of rubbing times and the rubbing force between the carrier and the toner are reduced as compared with the case where the amount of the staying developer is large, and the time for charging the toner in the developer transport path to the charge amount necessary for development. (Hereinafter referred to as charging start-up time) was found to be long. As described above, as a result of the charging start-up time becoming longer, the developer transport / stirring time in the developing transport path for raising the toner to a predetermined charge amount becomes longer, and the warm-up time of the apparatus becomes longer. As a result, the time until the first print is started is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device capable of suppressing an increase in the time until the first print is started and suppressing the rotation of the developer. The present invention also provides a process cartridge and an image forming apparatus provided with the same.

In order to achieve the above-mentioned object, the invention of claim 1 is characterized in that a developer containing toner and a carrier is carried on the surface and rotated, and the surface of the latent image carrier is developed in a development region facing the latent image carrier. A developer carrying member for supplying toner to the latent image of the toner and developing the developer carrying member, and facing the developer carrying member, while carrying the developer by a supply carrying member along the axial direction of the developer carrying member. A supply conveyance path for supplying the developer to the developer carrier, and a region between the development area of the developer carrier and a supply area from which the developer is supplied to the supply area; A recovery transport path for recovering the developer after passing through the development region from the developer support, and transporting the developer recovered from the developer support by a recovery transport member along the axial direction of the developer support; The downstream end of the supply conveyance path in the developer conveyance direction, A second communicating portion communicates with the upstream end in the developer transport direction of the recovery transport path, the upstream end in the developer transport direction of the supply transport path, and the downstream end in the developer transport direction of the recovery transport path. A developing unit that circulates and conveys the developer between the supply conveyance path and the recovery conveyance path, and further on the downstream side in the developer conveyance direction than the downstream end of the recovery conveyance path in the developer conveyance direction. A developer retention portion is provided to retain the developer conveyed from the collection conveyance path, the supply conveyance path is disposed above the collection conveyance path in the gravity direction, and the second communication section It is provided above the gravity direction at the downstream end in the developer conveyance direction of the conveyance path, and the surface provided above the gravity direction of the developer retaining portion is separated from the downstream end in the developer conveyance direction of the collection conveyance path. Inclination descending downward in the direction of gravity It is characterized in that the the.
According to a second aspect of the present invention, in the developing device of the first aspect, the developer retaining portion is configured such that the cross-sectional area decreases as the distance from the downstream end in the developer transport direction of the recovery transport path increases. To do.
According to a third aspect of the present invention, in the developing device according to the first or second aspect, the collecting and conveying member is extended to the developer retaining portion.
According to a fourth aspect of the present invention, there is provided the developing device according to the third aspect, wherein the collecting and conveying member includes a spiral screw portion on a rotating shaft, and the screw portion is located in the developer retaining portion of the collecting and conveying member. The winding direction of the screw is opposite to the winding direction of the screw part located in the collection conveyance path.
According to a fifth aspect of the present invention, in the developing device according to the third or fourth aspect of the present invention, the collecting and conveying member is configured not to contact an inner wall surface of the developer retaining portion.
According to a sixth aspect of the present invention, in the developing device according to any of the first to fifth aspects, the wall surface of the developer retaining portion is provided with irregularities.
The invention of claim 7, and a developing device for developing a latent image on the latent image bearing member and the latent image bearing member supported integrally, it is detachable from the image forming apparatus main body process In the cartridge, the developing device according to any one of claims 1 to 8 is used as the developing device.
Further, the invention of claim 8 provides a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a two-component developer containing a toner and a carrier. An image forming apparatus including: a developing device that develops a latent image; and a toner image formed on the latent image carrier by the developing device is finally transferred to a recording material to form an image on the recording material In the apparatus, the developing device according to any one of claims 1 to 7 is used as the developing device.
According to a ninth aspect of the present invention, in the image forming apparatus of the eighth aspect , at least the developing device and the latent image carrier are integrally supported, and a process cartridge that is detachable from the apparatus main body is provided. It is characterized by.
According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect, a plurality of the developing devices are provided.

  According to the present invention, the developer in the collection conveyance path is conveyed to the developer retention section provided downstream from the collection conveyance path, and the developer is retained in the developer retention section. Accordingly, the amount of staying developer staying downstream of the collection conveyance path can be reduced by the volume of the developer staying portion without reducing the amount of staying developer. As a result, while the number of rubbing times and the rubbing force between the carrier and the toner are suppressed, the staying developer in the collection conveyance path reaches the portion facing the downstream portion of the collection conveyance path of the developer carrier. Can be suppressed. As a result, it is possible to suppress the space where the developed developer on the developer carrier is collected while suppressing an increase in the charge start-up time. Therefore, it is possible to suppress the occurrence of developer rotation while suppressing an increase in the time until the first print is started.

  According to the present invention, it is possible to suppress the rotation of the developer while suppressing an increase in the time until the first print is started.

1 is a schematic configuration diagram of a printer according to an embodiment. FIG. 2 is a schematic cross-sectional view illustrating an example of a developing device applicable to the printer. FIG. 3 is an explanatory cross-sectional view in the vicinity of the rotation axis of each conveying screw when the developing device is viewed from the direction of arrow F in FIG. 2. FIG. 3 is a schematic diagram illustrating a developer flow in a developing container of the developing device when the developing device is viewed from the direction of arrow F in FIG. 2. FIG. 4 is a schematic diagram showing the magnetic flux density of each magnetic pole in the developing roller. FIG. 3 is a schematic cross-sectional view of a developing device configured to drop a developer that has not been held by a developing roller, out of a developer supplied to a buffer unit, into a collection conveyance path. FIG. 6 is a schematic diagram illustrating a sampling location of a developer for measuring a toner charge amount. The graph which shows the result of having investigated the charge start-up of the toner by varying the cross-sectional area of the lifting opening. 6 is a graph showing the relationship between the toner charge amount and the stirring time. Graph showing the toner saturation charge amount, the toner saturation charge amount when the cross-sectional area of the lift opening is 2 [cm ^2] when the cross-sectional area of the lift opening is 2 [cm ^2]. Graph showing the time constant of the time constant of the cross-sectional area of the lift opening is 2 [cm ^2], the cross-sectional area of the lift opening is 2 [cm ^2]. FIG. 6 is a schematic diagram for explaining a height of a developer surface in a collection conveyance path with respect to a distance from a lifting opening. The height of the developer surface in the recovery conveyance path with respect to the distance from the lifting opening when the sectional area of the lifting opening is 2 [cm ² ], and the sectional area of the lifting opening is 1 [cm ² ]. The graph which shows the height of the developer surface in a collection | recovery conveyance path with respect to the distance from the lifting opening part at the time. The graph which shows the result of having measured the pressure of the lifting opening vicinity. FIG. 4 is an explanatory cross-sectional view of the vicinity of the rotation axis of each conveyance screw in the developing device 3 of Embodiment 1. Sectional explanatory drawing of the rotating shaft vicinity of each conveyance screw in the developing device 3 of Example 2. FIG. 6 is a graph showing the results of examining the toner charge start-up time for the developing devices of Examples 1 and 2 and Comparative Example. 3 is a graph showing saturation charge amounts of developing devices of Examples 1 and 2 and a comparative example. 6 is a graph showing time constants of developing devices of Examples 1 and 2 and a comparative example. 6 is a graph showing the height of the developer surface in the collection conveyance path with respect to the distance from the lifting opening of the developing devices of Examples 1 and 2 and Comparative Example. Sectional explanatory drawing of the rotating shaft vicinity of each conveyance screw in the developing device of the modification 1. FIG. Sectional explanatory drawing of the rotating shaft vicinity of each conveyance screw in the developing device of the modification 2. FIG.

  Hereinafter, an embodiment in which the present invention is applied to a printer 100 as an image forming apparatus will be described. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description thereof will be simplified or omitted as appropriate.

FIG. 1 is a schematic configuration diagram of the printer 100.
The printer 100 is a color image forming apparatus that can form a full-color image using a tandem method, and forms toner images of each color of black, magenta, yellow, and cyan (hereinafter referred to as K, M, Y, and C, respectively). The image forming devices 17K, M, Y, and C are provided. Below these image forming devices 17K, 17M, 17C, and 17C, the recording paper P is carried on the surface and conveyed around the downstream stretching roller 18 and the upstream stretching roller 19, and each image forming device is conveyed. A transfer / conveying belt 15 that moves on the surface while facing the devices 17K, M, Y, and C is disposed. Transfer bias rollers 5K, M, Y, and C that face the image forming devices 17K, M, Y, and C with the transfer conveyance belt 15 interposed therebetween are provided.

  Further, a fixing device 24 that fixes unfixed toner on the recording paper P separated from the transfer conveyance belt 15 is provided downstream of the downstream tension roller 18 in the recording paper conveyance direction by the transfer conveyance belt 15. . In addition, a discharge tray 25 for stacking recording paper P that has passed through the fixing device 24 and has a toner image fixed thereon is provided at the top of the main body of the printer 100.

  A plurality of paper feed cassettes 20, 21, and 22 that store the recording paper P are provided below the transfer conveyance belt 15. Further, a paper feeding / conveying device 26 that supplies recording paper P as a recording material from each of the paper feeding cassettes 20, 21, and 22 to a transfer region where the transfer / conveying belt 15 and the image forming devices 17 </ b> K, M, Y, and C are opposed to each other. And a registration roller 23 for supplying the recording paper P conveyed from each of the paper feeding cassettes 20, 21, and 22 in accordance with the image forming timings of the image forming apparatuses 17K, 17M, 17C, and 17C.

  Further, in the printer 100 of the first embodiment, the transfer conveyance belt 15 is disposed in an oblique direction so that the size in the left-right direction in FIG. 1 can be reduced, and the conveyance direction of the recording paper P on the transfer conveyance belt 15 Is an oblique direction as indicated by an arrow in FIG. Accordingly, in the printer 100, the width of the housing in the left-right direction in FIG. 1 is slightly longer than the length in the longitudinal direction of the A3 size recording paper. With this configuration, the printer 100 according to the first embodiment can be configured to have a minimum size required to accommodate recording paper therein, and is greatly reduced in size.

  Each image forming device 17K, M, Y, C has a drum-shaped photoconductor 1K, M, Y, C as a latent image carrier. In order with respect to the rotation direction of the photoreceptors 1K, M, Y, and C, there are charging devices 2K, M, Y, and C, developing devices 3K, M, Y, and C, cleaning devices 6K, M, Y, and C, respectively. doing. Further, the writing light L is radiated from the exposure devices 16K, M, Y, C between the charging devices 2K, M, Y, C and the developing devices 3K, M, Y, C. The photoreceptors 1K, M, Y, and C may be belt-shaped instead of drum-shaped.

  In the printer 100 having such a configuration, each color toner image is formed by each image forming device 17K, M, Y, and C at the start of image formation. In each of the image forming devices 17K, M, Y, and C, the photoreceptors 1K, M, Y, and C are rotationally driven by a main motor (not shown) and are uniformly charged by the charging devices 2K, M, Y, and C. Thereafter, the exposure device 16K, M, Y, C emits the writing light L in accordance with the image information for each color obtained by color separation of the image, and an electrostatic latent image is formed. The electrostatic latent images formed on the photoreceptors 1K, M, Y, and C are developed by the developing devices 3K, M, Y, and C, and toner images of the respective colors are formed on the surfaces of the photoreceptors 1K, M, Y, and C. Is formed. On the other hand, the recording paper P fed and conveyed from any of the paper feeding cassettes 20, 21, and 22 is transferred by the registration roller 23 in accordance with the image forming timings of the image forming devices 17 K, M, Y, and C. Supplied on the surface. Then, the recording paper P carried on the transfer conveyance belt 15 is conveyed to the transfer area of each color by the surface movement of the transfer conveyance belt 15.

  The toner images formed on the photoconductors 1K, 1M, 1C, 1C are transferred to the transfer bias rollers 5K, 5M, 5B, and 5C, which are transfer bias means, at the facing portions of the photoconductors 1K, 1M, 1C, 1C and the transfer conveyance belt 15, respectively. The images are sequentially transferred onto the recording paper P carried on the transfer conveyance belt 15 by Y and C. In this way, the toner images formed on the photoreceptors 1K, M, Y, and C are transferred in the order of K, M, Y, and C, and a superimposed color toner image is formed on the recording paper P. The recording paper P onto which the toner image has been transferred is separated from the transfer conveyance belt 15 and conveyed to the fixing device 24 where the toner image is fixed and discharged to a paper discharge tray 25 outside the apparatus.

  On the other hand, after the toner image is transferred onto the recording paper P, the transfer residual toner is removed by the cleaning devices 6K, M, Y, and C, and the charge removal (not shown) is performed as necessary. After being neutralized by the lamp, the operation of being uniformly charged by the charging devices 2K, M, Y, and C is repeated again.

  Next, the developing device 3 will be described in detail. The developing devices 3K, M, Y, and C of the printer 100 according to the first exemplary embodiment use toners of different colors (K, M, Y, and C) as image forming materials, but otherwise have the same configuration. ing. For this reason, hereinafter, the subscripts K, M, Y, and C are omitted unless otherwise required, and the developing device 3 will be described.

FIG. 2 is a schematic cross-sectional view showing an example of the developing device 3 applicable to the printer 100 according to the first embodiment.
FIG. 3 is an explanatory cross-sectional view of the developing device 3 in the vicinity of the rotation axis of each conveying screw as seen from the direction of arrow F in FIG.
FIG. 4 is a schematic diagram illustrating the flow of the developer in the developing container 33 that is the casing of the developing device 3 when the developing device 3 is viewed from the direction of arrow F in FIG.
FIG. 5 is a schematic diagram showing the magnetic flux density of each magnetic pole in the developing roller 34.
Note that the arrows in FIGS. 3 and 4 indicate the flow of the developer in the developing container 33.

  As shown in FIG. 2, the developing device 3 is disposed opposite to the photoreceptor 1, and the photoreceptor 1 is driven to rotate clockwise in FIG. 2 as indicated by an arrow a in the figure. A developer container 33 that is a casing of the developing device 3 contains a developer 32 that is a powdery two-component developer composed of a magnetic carrier and magnetic or non-magnetic toner. The developing device 3 carries the developer 32 in the developing container 33 to the developing area A where the toner is supplied to the electrostatic latent image formed on the surface of the photoreceptor 1 to perform development, and is transported by moving the surface. A developing sleeve 34a is provided as a developer carrying member. The developing sleeve 34a includes a magnet roller 34b as a magnetic field generating unit composed of a plurality of magnets fixed to the developing device 3, and the developing sleeve 34a and the magnet roller 34b constitute the developing roller 34. Further, a developing doctor 35 is provided as a developer regulating member for regulating the layer thickness of the developer carried on the developing sleeve 34a.

  The magnet roller 34b of the present embodiment includes three magnetic poles S1, N1, and N2 along the developing sleeve surface movement direction. As shown in FIG. 5, the magnetic pole S <b> 1 acts in the development area A, causes the developer 32 that passes through the development area A to rise, and brings the toner held by the magnetic carrier into contact with the surface of the photoreceptor 1. This is the developing magnetic pole that has the function of developing the toner. The magnetic pole N1 acts in a region downstream of the developing region to ensure the transportability of the developer 32 by the rotation of the developing sleeve 34a and to separate the developer from the surface of the developing sleeve 34a. This is the magnetic pole away from the agent that plays a role. The magnetic pole N2 acts in the vicinity of the buffer portion D and the developing doctor 35, functions as a pumping magnetic pole that moves the developer 32 in the supply conveyance path 37 to the buffer portion D and pumps it onto the developing sleeve, and also develops the developing doctor 35. This is a pumping / regulating magnetic pole that also functions as a regulating magnetic pole that ensures the stability of the developer passing amount in the regulating gap by applying a magnetic force to the developer 32 that passes through the regulating gap.

  A supply screw 39 as a supply conveyance member and a recovery screw 40 as a recovery conveyance member are provided substantially parallel to the rotation axis direction of the developing sleeve 34a. As shown in FIG. 3, each conveying screw has a rotating shaft and a screw portion spirally provided on the rotating shaft. By rotating, each conveying screw develops in one direction along the axial direction of the rotating shaft. The agent 32 is conveyed. In the developing container 33, a supply conveyance path 37 and a collection conveyance path 38 are formed vertically with a partition wall 36 interposed therebetween.

  Moreover, as shown in FIG. 3, the opening part as a communication part is provided in the both ends of the partition wall 36, respectively. Here, the upstream side in the developer conveyance direction of the supply conveyance path 37 and the downstream side in the developer conveyance direction of the recovery conveyance path 38 communicate with each other by a lifting opening 41 as a second communication part. The recovery conveyance path 38 communicates with the upstream side in the developer conveyance direction by a drop opening 42 as a second communication portion. A toner replenishing port 45 for replenishing replenished toner is disposed above the drop opening 42.

  Here, as shown in FIG. 2, the partition wall 36 is erected so that the end on the developing sleeve 34 a side wraps the supply screw 39 from below, and a barrier 43 is formed by this erected portion. The upper space of the developing sleeve 34a formed by the barrier 43, the inner wall of the developing device 3, and the upper peripheral surface of the developing sleeve 34a (pre-regulation space adjacent to the upstream side of the developing sleeve 35 in the moving direction of the developing sleeve) The developer 32 is sequentially supplied from the supply conveyance path 37. In the upper space of the developing sleeve 34a, the stored developer 32 comes into contact with the peripheral surface of the developing sleeve 34a, and the developer 32 that comes into contact with the peripheral surface of the developing sleeve 34a as the developing sleeve 34a rotates rotates. It is formed over the development width so as to be carried and conveyed over the entire width of the rotation axis direction 34a. The space above the developing sleeve 34a functions as a buffer portion D that is a supply storage portion that temporarily stores the developer 32 supplied from the supply conveyance path 37, and the stored developer 32 is stably supplied to the developing sleeve 34a. To supply.

  In the developing device 3 in the present embodiment, the amount of the developer 32 in the supply conveyance path 37 tends to decrease as it goes downstream, so that the height of the end portion of the barrier 43 is upstream so that the amount decreases. You may form so that it may become low as it goes downstream from. As shown in FIG. 3, the developer 32 in the collection conveyance path 38 is conveyed by the collection screw 40 in the direction opposite to the conveyance direction of the supply screw 39. Further, the supply screw 39 rotates clockwise in FIG. 2, and the recovery screw 40 rotates counterclockwise similarly to the developing sleeve 34a. As shown in FIG. 4, the developer 32 in the developing container 33 is transported toward the transporting direction of the supply transporting path 37 and the recovery transporting path 38 by the rotation of the supply screw 39 and the recovery screw 40, so Circulate.

  The developer 32 is transported from the recovery transport path 38 to the supply transport path 37 by the transport pressure of the developer 32 accumulated at the downstream end in the transport direction by the recovery screw 40 provided in the recovery transport path 38. The developer 32 is pushed upward in the vertical direction so as to pass through a lifting opening 41 that communicates with the recovery conveyance path 38. The developer 32 transported in the supply transport path 37 sequentially passes over the end of the barrier 43 between the supply screw 39 and the developing sleeve 34a by the rotation of the supply screw 39 along the developer transport direction. To D. The developer 32 supplied to the buffer portion D is attracted to the developing sleeve 34a directly or by the magnetic force of the magnet roller 34b provided in the developing sleeve 34a, and is supplied to the developing sleeve 34a.

  The developer 32 supplied to the developing sleeve 34a via the buffer portion D is carried on the surface of the developing sleeve 34a by the rotation of the developing sleeve 34a and the magnetic force of the magnet roller 34b provided therein. 2 in the direction of arrow B. Then, a certain amount of the developer 32 supplied and carried to the developing sleeve 34a via the buffer portion D is carried on the developing sleeve 34a, while being carried on the developing sleeve 34a, as indicated by the arrow B, It passes through a regulation gap with the developing doctor 35. At this time, excess developer out of the developer 32 carried on the surface of the developing sleeve 34a is blocked from passing by the developing doctor 35 when passing through the regulation gap, as shown by an arrow B1 in FIG. It remains in the buffer part D.

  The developer 32 that has passed through the regulation gap passes through the developing area A between the developing sleeve 34a and the photoreceptor 1 as indicated by an arrow B2 in FIG. To the collection conveyance path 38. More specifically, first, the developer 32 that has passed through the regulation gap is carried on the developing sleeve 34a, conveyed to the developing area A, and passes through the developing area A. Thereafter, the developer 32 remaining on the developing sleeve 34a without being supplied to the surface of the photoreceptor 1 in the developing region A is not collected again in the supply conveyance path 37 as the developing sleeve 34a rotates, but is collected. It is collected in the conveyance path 38. Then, the collected developer 32 is conveyed while being agitated in the collected conveyance path 38 with the replenished toner, and is transferred to the supply conveyance path 37 again. In this way, the developer 32 that has passed through the development region A circulates through the supply conveyance path 37 and the collection conveyance path 38 in the developing container 33, and therefore, the supply conveyance path 37 is always sufficiently agitated in the collection conveyance path 38. Only the developer is present.

  Further, since the developer 32 in the collection conveyance path 38 includes the developer 32 that has passed through the development region A and has a reduced toner concentration, it is necessary to replenish the toner. Accordingly, the toner is supplied to the developer 32 on the upstream side of the recovery conveyance path 38 according to the toner consumption calculated from the image information of the latent image or according to the measurement result of the toner concentration of the developer 32 in the recovery conveyance path 38. Supply is made. As shown in FIG. 3, the toner replenished into the developing container 33 falls from the toner replenishing port 45 through the drop opening 42 to the upstream end of the collection transport path 38 in the transport direction. The dropped replenishment toner is replenished to the developer 32 in the collection conveyance path 38 and is agitated and conveyed in the collection conveyance path 38. In this way, the developer 32 having an appropriate toner concentration can be transferred to the supply conveyance path 37.

  In the developing device 3 of the present embodiment, the developer that has been supplied from the supply conveyance path 37 to the development sleeve 34 a and has passed through the development region A and has a decreased toner concentration is located at a position facing the recovery conveyance path 38 from the surface of the development sleeve 34 a. It separates and is collected in the collection conveyance path 38. The developer collected in the collection conveyance path 38 is agitated in the collection conveyance path 38 with the toner replenished at the upstream end in the conveyance direction in the collection conveyance path 38, and in a state where a desired toner concentration is obtained. It is supplied to the supply conveyance path 37. As described above, in the developing device 3 of the present embodiment, the developer whose toner density has decreased after passing through the developing area A is not collected in the supply conveyance path 37 and is thus supplied on the upstream side and the downstream side in the conveyance direction by the supply screw 39. The toner density of the developer 32 in the transport path 37 does not change.

  Further, in the developing device 3 shown in FIG. 2, the developer 32 supplied to the buffer unit D is supplied to the buffer unit D by setting the gap between the partition wall 36 and the developing sleeve 34 a to 0.5 to 1.0 [mm]. As shown in FIG. 6, the gap between the developing sleeve 34a and the partition wall 36 is set to 3.0 [mm] or more, and the pumping magnetic pole of the developer 32 supplied to the buffer portion D is drawn. The developer 32 that could not be held by N2 may be dropped from the gap to the collection conveyance path 38. Note that when the gap between the developing sleeve 34a and the partition wall 36 is less than 3.0 [mm], the developer 32 cannot be stably dropped onto the collection conveyance path 38.

  In this embodiment, since the force of gravity is also used when the developer is conveyed / supplied from the supply screw 39 to the developing roller 34, the developer can be conveyed even if the magnetic flux density of the pumping magnetic pole is lowered. Accordingly, the magnetic flux density in the developing doctor 35 can be reduced, the stress applied to the developer in the developing doctor 35 can be reduced, and deterioration of the developer can be suppressed, so that the life of the developer can be extended. However, since the rubbing force at the developing doctor 35 is small, the toner charging function at the developing doctor 35 is lowered. Therefore, it is necessary to charge the toner to a predetermined charge amount in the supply conveyance path 37 and the collection conveyance path 38.

  Therefore, the present inventors conducted the following experiment on the toner charging performance in the supply conveyance path 37 and the collection conveyance path 38, and as a result, the smaller the sectional area of the lifting opening 41, the more the toner is charged. It has been found that the charging performance can be increased. Hereinafter, the experiments conducted by the inventors will be described in detail.

First, the present inventors investigated the charging start-up of the toner by changing the cross-sectional area of the lifting opening 41. Specifically, in the developing device 3 from which the developing roller 34 has been removed, the supply screw 39 and the recovery screw 40 are rotated in a high-humidity environment, and the developer whose toner charge amount has been reduced is stirred and conveyed, and the stirring time is increased. The relationship between the toner charge amount and the toner charge amount was obtained with a V blow device. As the shape of the lifting opening 41, as shown in FIG. 7, a rectangular shape having a cross-sectional area X of 2 [cm ² ] and a rectangular shape having a cross-sectional area X of 1 [cm ² ] were prepared. . Further, the developer in a region slightly downstream of the developer conveyance direction 37 in the developer conveyance direction (region S surrounded by the slanted line in FIG. 7) of the supply conveyance path 37 is sampled, and immediately after passing through the elevation opening 41. The charge amount of the toner was measured. The result is shown in FIG.

It is said that the rise of toner charge (the relationship between the toner charge amount and the stirring time) can be expressed by the relationship shown in FIG. 9, and the relational expression showing the relationship shown in FIG. Equation (1) is obtained.
Q = Q ₀ + pot (1−exp (−t / τ)) (1)
Q0: initial charge amount pot: saturation charge amount-initial charge amount τ: time constant (half value of rise time)
t: Stirring time

The saturation charge amount Pot and the time constant τ were obtained from the above relational expression and the experimental results shown in FIG. The results are shown in FIGS.
As can be seen from FIG. 8, FIG. 10, and FIG. 11, it can be seen that when the opening has a rectangular shape of 1 [cm ² ], the rising of the charge is quicker and the saturation charge amount is higher.

Next, in the case where the cross-sectional area of the lifting opening 41 is a rectangular shape of 2 [cm ² ], the amount of developer staying on the downstream side of the collection conveyance path 38 (region 101 surrounded by the dotted line in FIG. 7), The amount of developer staying at the downstream end of the collection conveyance path 38 in the case where the lifting opening 41 has a rectangular shape with a cross-sectional area of 1 [cm ² ] was examined.
Since it is difficult to measure the amount of developer staying on the downstream side of the collection conveyance path 38, the developer is stirred and conveyed until the agent balance is achieved, and then in a state of being stationary, as shown in FIG. The height of the developer surface in the collection conveyance path 38 with respect to the distance from 41 was measured. The measurement results are shown in FIG. From the experimental results, it can be seen that the developer surface is higher in the cross-sectional area of 1 [cm ² ] even at a position farther from the lifting opening 41 than 2 [cm ² ]. In other words, it can be seen that the smaller the opening area, the larger the amount of developer staying on the downstream side of the collection conveyance path 38.

Next, a small compression load cell (manufactured by Kyowa Denki) is provided in the vicinity of the opening of the holding upper part, and the developer is stirred and conveyed by the supply screw 39 and the recovery screw 40 using the developing device 3 from which the developing roller 34 is removed. The pressure was measured. The result is shown in FIG. In this experiment, rectangular objects having a cross-sectional area of the lifting opening 41 of 1 [cm ² ], 1.3 [cm ² ], 2 [cm ² ] are prepared, and pressure is applied in each shape. It was measured.

  As shown in FIG. 14, it can be seen that the pressure is higher when the cross-sectional area of the lifting opening 41 is reduced. This is considered to be that by reducing the cross-sectional area of the lifting opening 41, the amount of developer staying at the downstream end of the recovery conveyance path 38 is increased and the pressure is increased.

  From the above experimental results, by reducing the opening area of the lifting opening 41, the developer accumulates at the downstream end of the collection conveyance path 38 and becomes in a compacted state, so that the rising of the charge is quick and the saturation charge amount is increased. It turns out that the function improves.

  As described above, the charging function is improved by narrowing the cross-sectional area of the lifting opening 41 and storing the developer at the downstream end of the collection conveyance path 38 to be in a compacted state, but the downstream end of the collection conveyance path 38 is improved. When the developer accumulates on the surface, a problem that the developer accompanies is generated. As shown in FIG. 13, the location where the developer surface is high and the developer stays extends to a location far from the lifting opening 41. Therefore, the portion where the developer stays extends to the area facing the developing roller 34, and the space for collecting the developed developer on the surface of the developing sleeve 34 a to the collection conveyance path 38 is blocked. As a result, the developed developer is not collected in the collection conveyance path 38 but is conveyed again to the development area A and used for development. Since the developer that has been developed has once passed through the development area A and consumed toner, the toner concentration is low. Therefore, when the developed developer is transported again to the development area A, a predetermined amount of toner can be attached to the latent image, and the image density becomes lighter than other parts, and the image Density unevenness occurs.

  By providing the lifting opening 41 at a position away from one end of the developing roller 34, the developer staying on the downstream side of the collection conveyance path does not reach the area facing the developing roller, and the developer is not rotated. In this case, since both the recovery conveyance path 38 and the supply conveyance path 37 become longer in the axial direction, the developing device becomes larger in the axial direction.

  Therefore, in the present embodiment, a developer retention portion for storing the developer that stays in the recovery conveyance path 38 is provided downstream of the lifting opening 41 of the recovery conveyance path 38 in the developer conveyance direction. The developer was retained in the developer retaining portion, and the amount of retained developer in the recovery conveyance path was reduced. This will be specifically described below.

[Example 1]
FIG. 15 is a cross-sectional explanatory view of the vicinity of the rotation shaft of each conveying screw in the developing device 3 of the first embodiment.
As shown in FIG. 15, in the developing device 3 according to the first embodiment, a developer retention portion 102 is provided on the downstream side of the downstream end of the collection conveyance path 38 in the developer conveyance direction. The developer retaining part 102 is parallel to the developer transport direction and has a triangular cross section when cut in the vertical direction. More specifically, the upper side surface 103 on the upper side in the gravity direction of the developer retaining portion 102 is an inclined surface such that the cross-sectional area of the developer retaining portion 102 becomes larger toward the collection conveyance path 38.

  Further, the recovery screw 40 is extended to the developer retention part 102. Further, the height of the screw portion 40b-2 located in the developer retaining portion 102 of the recovery screw 40 is adjusted so as not to contact the wall surface of the developer retaining portion 102. That is, the height a from the rotating shaft 40a of the screw part located at a position away from the collection conveyance path 38 is shorter than the height b of the screw part on the collection conveyance path 38 side.

  The developer 32 in the collection conveyance path 38 is conveyed to the developer retention unit 102 by the collection screw 40. The developer retaining portion 102 has a shape in which the cross-sectional area decreases as the developer retention portion 102 moves away from the collection conveyance path 38. For this reason, the developer 32 that has been transported to the developer retaining portion 102 is transported to the back side of the developer retaining portion 102 by the recovery screw 40, thereby bringing the developer into a compacted state. As a result, the number of rubbing times and the rubbing force between the toner and the carrier are increased on the back side of the developer retaining portion 102, and the toner can be quickly brought to a predetermined charge amount. The developer 32 conveyed to the back side of the developer retention part 102 is pushed by the developer 32 conveyed later and pushed up to the inclined upper side surface 103 side. Then, as indicated by an arrow G, while being moved along the inclined upper side surface 103, it is conveyed to the lifting opening 41 and conveyed to the supply conveyance path 37. As described above, in the developer retention portion 102, the developer conveyance direction on the upper side is opposite to the developer conveyance direction on the recovery screw 40 side. The number of times of rubbing can be increased, and the toner can be quickly brought to a predetermined charge amount.

  Further, by setting the upper side surface 103 to be an inclined surface, the developer in the developer retaining portion 102 can be smoothly conveyed toward the lifting opening 41 from the recovery conveyance path. As a result, it is possible to suppress the developer from staying in the developer staying portion 102 for a long time. Further, by extending the collection screw 40 in the developer retaining portion 102, the developer in the developer retaining portion 102 can be agitated, and the friction between the toner and the carrier can be promoted. As a result, the toner can be frictionally charged satisfactorily.

  In this way, by transporting the developer to the developer retaining portion 102 and retaining the developer in the developer retaining portion 102, the amount of developer remaining in the collection transport path can be reduced. Thereby, it is possible to suppress the staying developer in the collection conveyance path from reaching the area facing the developing roller 34. As a result, it is possible to suppress the staying developer in the recovery conveyance path from blocking the space where the developed developer on the surface of the developing sleeve 34a is recovered, and to suppress the occurrence of the developer accompanying the developer. Can do.

  In addition, since the cross-sectional area of the developer retaining portion 102 is reduced as the distance from the collection conveyance path 38 increases, a compacted state can be created even if the amount of the developer retained in the developer retaining portion 102 is small, and the toner can be removed. Good triboelectric charging. As a result, as shown in an experiment to be described later, even when the sectional area of the lifting opening 41 is widened and the amount of developer to be retained is reduced, the toner can be quickly charged to a predetermined charge amount. Moreover, since the volume of the developer retaining portion can be reduced, the development device can be prevented from being enlarged. Further, by providing the developer retaining portion 102, the lower side of the developing device becomes longer in the axial direction, but the upper side having the supply conveyance path 37 has the same axial length as the conventional developing device. Can do. Therefore, by separating the lifting opening 41 from one end of the developing roller, the size of the developing device in the axial direction can be minimized as compared with the case where the accompanying rotation of the developer is suppressed.

[Example 2]
FIG. 16 is an explanatory cross-sectional view of the vicinity of the rotation shaft of each conveying screw in the developing device 3 of the second embodiment.
In the second embodiment, the upper side surface 103 is provided with irregularities. Thus, by providing irregularities, when the developer 32 moves to the lifting opening along the upper side surface 103, it is possible to increase the number of times and the rubbing force between the toner and the carrier, The toner can be quickly brought to a predetermined charge amount. Other configurations are the same as those of the developing device of the first embodiment. Further, in the configuration shown in FIG. 16, irregularities are provided only on the upper side surface 103, but irregularities may be provided on all the wall surfaces of the developer retaining portion 102.

  The following experiment was conducted using the developing device of Example 1 shown in FIG. 15, the developing device of Example 2 shown in FIG. 16, and the developing device of the comparative example not having the developer retaining portion 102. It was.

In the experiment, the developing roller 34 is removed from each developing device, and the developer whose toner charge amount is reduced is charged into the supply conveyance path 37 and the collection conveyance path 38, and the supply screw 39 and the collection are collected under the experimental conditions shown in Table 1. The developer was stirred and conveyed by rotating the screw 40, and the relationship between the stirring time (driving time of the supply screw 39 and the recovery screw 40) and the charge amount of the toner was acquired by a V blow device. The lifting opening 41 of each developing device has a rectangular shape with a cross-sectional area of 2 [cm ² ]. Further, the toner in the region slightly downstream of the supply conveyance path 37 in the developer conveyance direction (same location as the region S surrounded by the diagonal line in FIG. 7) was sampled. That is, the charge amount of the toner immediately after passing through the lifting opening 41 was measured. The experimental results are shown in FIG.

  Next, the saturation charge amount Pot and the time constant τ were obtained based on the previous equation (1) and the experimental results shown in FIG. The results are shown in FIGS.

As shown in FIGS. 17 to 19, by providing the developer retaining portion 102, the toner charging time constant τ becomes faster compared to the developing device of the comparative example in which the developer retaining portion is not provided, and the saturated charge amount Pot. It turns out that becomes high. Moreover, the developing device of Example 2 with the upper surface 103 provided with irregularities is substantially the same as the developing device in which the sectional area of the lifting opening 41 shown in FIGS. 10 and 11 is 1 [cm ² ]. The time constant τ and the saturation charge amount Pot could be achieved. As described above, in the developing devices according to the first and second embodiments, in which the developer retention portion 102 is provided that decreases in cross-sectional area toward the inner side, the toner is predetermined even when the cross-sectional area of the lifting opening 41 is increased. It was found that it can be charged quickly to the amount of charge. As described above, even if the amount of the developer retained in the developer retaining portion 102 is small, the developer can be brought into a compacted state at a portion where the cross-sectional area on the back side of the developer retaining portion 102 is small. Therefore, even if the amount of the developer staying is small, the number of times of rubbing between the toner and the carrier can be increased, and the rubbing force can be increased. It is thought that the charge amount could be charged quickly. As described above, even when the cross-sectional area of the lifting opening 41 is widened to reduce the amount of developer to be retained, the toner can be quickly charged to a predetermined charge amount. Accordingly, the developer can be prevented from staying on the downstream side of the collection conveyance path 38, and the toner can be quickly charged to a predetermined charge amount. Therefore, it is possible to prevent the developer staying in the collection conveyance path 38 from blocking the space for collecting the developed developer on the developing sleeve 34a while obtaining the function of quickly charging the toner to a predetermined charge amount. And the rotation of the developer can be suppressed. Further, the developing device of Example 2 was able to increase the time constant τ and increase the saturation charge amount Pot as compared with the developing device of Example 1. This is probably because the number of rubbing times and rubbing force between the toner and the carrier can be increased by making the wall surface of the developer retaining portion 102 uneven.

Next, using the developing devices of Examples 1 and 2 and the developing device of the comparative example, the amount of developer staying on the downstream side of the collection conveyance path 38 was examined.
Since it is difficult to measure the amount of the developer staying on the downstream side of the collection conveyance path 38, the developer is stirred and conveyed until the agent balance is achieved, and then lifted as shown in FIG. The height of the developer surface in the collection conveyance path 38 with respect to the distance from the opening 41 was measured. The measurement results are shown in FIG.

  As can be seen from FIG. 20, the height of the developer on the downstream side of the collection conveyance path 38 of the developing devices of Examples 1 and 2 can be made lower than that of the developing device of the comparative example. This is considered to be because by providing the developer retaining portion 102, the height of the developer on the downstream side of the collection conveyance path 38 can be reduced by the volume of the developer retaining portion 102. As described above, in the developing devices of Examples 1 and 2, compared to the developing device of the comparative example, the height of the developer on the downstream side of the collection conveyance path 38 can be suppressed. Thereby, when the developer in the collection conveyance path 38 is stirred and conveyed, the scattered developer can be prevented from adhering to the surface of the developing sleeve.

FIG. 21 is an explanatory cross-sectional view of the vicinity of the rotation axis of each conveying screw in the developing device according to the first modification.
The developing device of Modification 1 shown in FIG. 21 is obtained by reversing the winding direction of the screw part 40b-2 of the recovery screw 40 located in the developer retaining part 102 with respect to the screw part 40b-1 located in the recovery conveyance path 38. It is. With this configuration, when the collection screw 40 rotates, the developer in the developer retaining portion 102 is conveyed toward the collection conveyance path 38 by the collection screw 40. Thereby, it is possible to suppress the developer from staying in the developer retaining portion 102. In addition, the developer at the downstream end 101 of the collection conveyance path 38 is sandwiched between the developer conveyed from the developer retention section 102 and the developer conveyed from the collection conveyance path 38, and is in a compacted state. Can be. As a result, the number of rubbing times and rubbing force between the carrier and the toner can be increased, and charging of the toner can be promoted.

FIG. 22 is an explanatory cross-sectional view of the vicinity of the rotation axis of each conveying screw in the developing device of Modification 2.
In the developing device of Modification 2 shown in FIG. 22, the recovery screw 40 is not extended to the position in the developer retaining portion 102. Even in such a configuration, the developer 32 transported to the downstream end 101 of the recovery transport path is transported to the developer retention unit 102 by the recovery screw 40. Then, the developer in the developer retaining portion is pushed by the developer 32 that has been transported to the developer retaining portion 102 later, so that the developer is transported to the inner side of the developer retaining portion 102 as indicated by an arrow G. Then, when it reaches the far side, it is lifted by the developer 32 that has been transported to the developer retaining portion 102 and transported along the upper side surface 103. And it is conveyed along the upper side surface 103 to the lifting opening part 41, and is conveyed from the lifting opening part 41 to the upstream end of a supply conveyance path.

  As described above, the developing device of the present embodiment carries the developer 32 including the toner and the carrier on the surface and rotates, and the latent image on the surface of the photosensitive member 1 is developed in the developing region facing the photosensitive member 1 as the latent image carrier. A developing roller 34 is provided as a developer carrier for supplying toner to the image and developing the image. Further, the supply and transport for supplying the developer 32 to the developing roller 34 while transporting the developer 32 by the supply screw 39 which is disposed opposite to the developing roller 34 and is a supply and transport member along the axial direction of the developing roller 34. A path 37 is provided. Further, the developer roller 34 is disposed opposite to a region from the development region to the supply region to which the developer 32 is supplied from the supply conveyance path 37, and the developer 32 after passing through the development region from the development roller 34. And a recovery conveying path 38 for conveying the developer recovered from the developing roller 34 by a recovery screw 40 as a recovery conveying member along the axial direction of the developing roller 34. Further, a drop opening 42 serving as a first communication portion that communicates the downstream end of the supply transport path 37 in the developer transport direction and the upstream end of the recovery transport path 38 in the developer transport direction, and development of the supply transport path 37. A lifting opening 41 is provided as a second communicating portion that communicates the upstream end in the agent transport direction and the downstream end in the developer transport direction of the recovery transport path 38. In addition, a developer retaining portion 102 that retains the developer 32 is provided on the downstream side in the developer transport direction with respect to the lifting opening 41 of the collection transport path 38. As a result, the developer in the recovery conveyance path 38 is conveyed to the developer retention part 102 and stays in the developer retention part. As a result, the amount of the developer staying in the recovery conveyance path can be reduced by the volume of the developer retention portion, and the staying developer in the recovery conveyance path can reach the area facing the developing roller 34. Can be suppressed. Therefore, the staying developer in the collection conveyance path 38 can be prevented from closing the space where the developed developer on the surface of the developing sleeve 34a is collected, and the occurrence of development accompanying rotation can be suppressed.

  In addition, the developer retaining portion 102 is configured so that the cross-sectional area decreases as the distance from the downstream end of the recovery conveyance path 38 in the developer conveyance direction increases. Thereby, the developer conveyed to the developer retention part 102 is pushed by the developer conveyed later and is conveyed to the back side having a small cross-sectional area, so that the compacted state can be achieved. As a result, even if the amount of the developer staying in the developer staying portion 102 is small, a compacted state can be created and the toner can be satisfactorily charged with toner. As described above, since the amount of the developer staying in the developer staying portion 102 can be reduced, the volume of the developer staying portion can be reduced, and the enlargement of the apparatus can be suppressed.

  Further, by extending the recovery screw 40 to the developer retaining portion 102, the developer 32 in the developer retaining portion 102 can be stirred, and the friction between the toner and the carrier can be promoted. As a result, the toner can be frictionally charged satisfactorily.

  Further, the winding direction of the screw part 40b-2 located in the developer retaining part 102 of the collection screw 40 may be opposite to the winding direction of the screw part 40b-1 located in the collection conveyance path 38. Thereby, when the collection screw 40 is rotated, the developer 32 in the developer retention portion 102 is conveyed toward the collection conveyance path 38. Thereby, it is possible to prevent the developer from staying in the developer retaining portion 102 for a long time.

  Further, by configuring the recovery screw 40 so as not to contact the inner wall surface of the developer retaining part 102, it is possible to prevent the inner wall surface of the developer retaining part 102 and the recovery screw 40 from being worn.

  By providing irregularities on the wall surface of the developer retaining portion 102, when the developer 32 in the developer retaining portion moves along the wall surface, it is possible to increase the number of times and the rubbing force between the toner and the carrier. As a result, the toner can be quickly charged to a predetermined charge amount.

  Further, the supply conveyance path 37 is disposed above the collection conveyance path 38 in the gravity direction. As a result, the horizontal width of the developing device can be reduced, and the size of the device can be reduced.

  Furthermore, the upper side surface 103 provided above the developer retaining portion 102 in the direction of gravity is an inclined surface that descends downward in the direction of gravity as it moves away from the downstream end of the collection transport path 38 in the developer transport direction. As a result, the developer charged in the developer retaining portion 102 can smoothly transport the toner charged to a predetermined charge amount to the lifting opening 41 along the upper side surface 103.

1: Photoconductor 3: Developing device 34: Developing roller 37: Supply conveyance path 38: Collection conveyance path 39: Supply screw 40: Collection screw 40a: Rotating shaft 40b: Screw part 41: Lifting opening 42: Dropping opening 102 : Developer retention part 103: Upper side

Japanese Patent Laid-Open No. 11-272062

Claims (10)

A developer carrying body that carries a developer containing toner and a carrier on the surface, rotates, supplies the toner to the latent image on the surface of the latent image carrier and develops it in a development area facing the latent image carrier. When,
A supply conveyance path that is disposed to face the developer carrying member and supplies the developer to the developer carrying member while conveying the developer by a supply conveying member along the axial direction of the developer carrying member;
The developer carrying member is disposed opposite to a region from the developing region to the supply region where the developer is supplied from the supply conveyance path, and collects the developer after passing the developing region from the developer carrying member. A recovery transport path for transporting the developer recovered from the developer support by a recovery transport member along the axial direction of the developer support;
A first communicating portion that communicates the downstream end of the supply transport path in the developer transport direction and the upstream end of the recovery transport path in the developer transport direction;
A second communication portion that communicates the upstream end of the supply transport path with respect to the developer transport direction and the downstream end of the recovery transport path with respect to the developer transport direction;
In the developing device that circulates and conveys the developer between the supply conveyance path and the recovery conveyance path ,
Provided on the downstream side of the developer conveyance direction of the recovery conveyance path downstream of the developer conveyance direction is a developer retention portion that retains the developer conveyed from the collection conveyance path ,
The supply transport path is disposed above the collection transport path in the direction of gravity,
The second communication portion is provided above the gravity direction at the downstream end of the recovery conveyance path in the developer conveyance direction,
2. A developing device according to claim 1, wherein a surface provided above the developer retaining portion in the direction of gravity is an inclined surface that descends downward in the direction of gravity as the distance from the downstream end in the developer transport direction of the recovery transport path . The developing device according to claim 1.
2. A developing device according to claim 1, wherein the developer retaining portion is configured such that the cross-sectional area decreases as the distance from the downstream end in the developer transport direction of the recovery transport path increases. The developing device according to claim 1 or 2,
2. A developing apparatus according to claim 1, wherein the collecting and conveying member is extended to the developer retaining portion. The developing device according to claim 3.
The collection conveyance member includes a spiral screw portion on the rotation shaft,
A developing device characterized in that the winding direction of the screw portion located in the developer retaining portion of the collecting and conveying member is opposite to the winding direction of the screw portion located in the collecting and conveying path. The developing device according to claim 3 or 4,
2. A developing apparatus according to claim 1, wherein said collecting and conveying member is configured not to contact an inner wall surface of said developer retaining portion. The developing device according to any one of claims 1 to 5,
A developing device characterized in that an unevenness is provided on the wall surface of the developer retaining portion. In a process cartridge that integrally supports a latent image carrier and a developing device that develops a latent image on the latent image carrier and is configured to be detachable from the image forming apparatus main body,
As the developing apparatus, process cartridge characterized by using any of the developing apparatus of claims 1 to 6. A latent image carrier, a latent image forming unit that forms a latent image on the latent image carrier, and a developing device that develops the latent image on the latent image carrier using a two-component developer containing toner and a carrier. An image forming apparatus for forming an image on the recording material by finally transferring the toner image formed on the latent image carrier by the developing device to the recording material,
As the developing device, an image forming apparatus characterized by using any of the developing apparatus according to claim 1 to 7. The image forming apparatus according to claim 8 .
An image forming apparatus comprising a process cartridge that integrally supports at least the developing device and the latent image carrier and is detachable from the apparatus main body. The image forming apparatus according to claim 8 or 9 ,
An image forming apparatus comprising a plurality of the developing devices.

Images