JP6107076B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device, a process cartridge including the developing device, and an image forming apparatus such as a copying machine, a printer, and a facsimile including the developing device or the process cartridge.

  2. Description of the Related Art Conventionally, there are known two-component developing type developing devices using a two-component developer containing a carrier and toner (hereinafter referred to as “developer” as appropriate), and image forming apparatuses such as copiers, printers, and facsimiles. It is used for. In the two-component developing type developing apparatus, two or three horizontally arranged screws as developer conveying members are arranged, and one of them is set as a supply screw so as to face a developing sleeve as a developer carrier. Was common. In the developing device having such a configuration, the supply and recovery of the developer proceed simultaneously between the developing sleeve and the supply screw.

  Also, in order to improve the image quality of continuous solid images (solid images) and halftone images as colorization progresses, a supply screw that supplies developer to the developing sleeve and a collection screw that collects developer from the developing sleeve are provided. A developing device arranged in the vertical direction has been proposed. In this developing device, the developer is circulated and conveyed in one direction in the developing device in order to separately supply and collect the developer to the developing sleeve.

For example, in Patent Document 1, two screws whose developer transport directions are opposite to each other are arranged above and below, a developer reservoir for stirring for developer stirring, and a developer for supplying for supplying developer. A developing device is disclosed in which the developer is circulated and conveyed between the agent reservoir.
In Patent Document 2, a stirring chamber for stirring a developer is arranged vertically above a developing chamber for performing development on an image carrier by a developing sleeve, and the developer is formed between the stirring chamber and the developing chamber. A developing device provided with a conveying screw whose conveying directions are opposite to each other is disclosed. This developing device has a partition that partitions the agitating chamber and the developing chamber except for the developer passages provided at both ends in the longitudinal direction in the developing container for transferring the developer from the agitating chamber to the developing chamber. ing. The developer carrying member conveys the developer so that the developer cut off in the developing chamber passes through the developing region and is taken into the stirring chamber.

  In the developing devices of Patent Document 1 and Patent Document 2, in order to circulate the developer in one direction and supply a sufficient amount of developer to the developing sleeve after stirring, it is necessary to improve the developer conveying ability by the screw. There is. As a configuration for improving the developer conveying capability by this screw, it is conceivable to increase the screw diameter, optimize the screw pitch, increase the screw rotation speed, etc. However, in recent years, downsizing of the apparatus is desired from the viewpoint of resource saving. Therefore, in many cases, the screw rotation speed is increased rather than the expansion of the screw diameter.

  However, when the rotational speed of the screw is increased, there is a problem that the durability of the seal member that seals the bearing portion of the screw shaft is lowered. That is, in a developing device equipped with a screw, a seal member made of rubber or sponge is slidably brought into contact with the screw shaft so that the developer does not leak from the bearing portion of the screw shaft to the outside of the developing device. It is common. When the screw shaft bearing is sealed with such a seal member, if the rotational speed of the screw is increased, the wear of the seal member sealing the screw shaft bearing proceeds and the durability of the seal member decreases. Resulting in.

  In particular, a developing device mounted on an image forming apparatus capable of high-speed output is required to have high image quality and high durability. In order to achieve high durability of the developing device, it is necessary to improve the durability of the seal member. In order to improve the durability of the seal member, it is effective to improve the sealability between the seal member and the screw shaft. In order to improve the sealing performance between the seal member and the screw shaft, for example, the contact area between the seal member and the screw shaft is increased, the elastic deformation amount of the seal member with respect to the screw shaft is increased, or the number of seal members is increased. It is conceivable to increase the load applied to the screw shaft of the seal member by increasing the load.

  However, if the sealing performance between the seal member and the screw shaft is improved, the load torque of the developing device increases, or the temperature of the developing device increases due to frictional heat between the seal member and the screw shaft. There is a problem to do. An increase in the load torque of the developing device means that the input energy increases, which is not preferable from the viewpoint of energy saving. Further, the temperature rise of the developing device may cause the toner in the developer to harden and cause an abnormal image such as a black spot. Further, when the temperature of the developing device rises, there is a possibility that the screw shaft is locked due to toner adhering to the seal member and the developing device (developing unit) is damaged.

  Note that the above problem associated with the improvement in sealing performance between the seal member and the screw shaft is that the developing device having a developer conveying member that conveys the developer in one direction can be used in a two-component developing type developing device. The problem is not limited to the one-component developing system.

  The present invention has been made in view of the above problems, and the object thereof is to develop even if the rotation speed of the developer conveying member is increased in order to improve the developer conveying ability of the developer conveying member. Developing device, process cartridge, and image forming apparatus capable of suppressing increase in load torque and temperature while maintaining high durability of seal member for preventing leakage of developer from both ends of rotation shaft of agent transport member Is to provide.

In order to solve the above problems, the invention described in claim 1 is directed to a developer accommodating member that accommodates a developer, and a developer accommodated in the developer accommodating member that faces the image carrier. A developer carrying member transported to the developing region and a bearing provided on the developer containing member are rotatably supported at both axial ends of the rotation shaft, and the developer contained in the developer containing member is pivoted. A developing device comprising: a plurality of developer conveying members that are conveyed in a direction; and each rotation shaft of the plurality of developer conveying members and a seal member that is slidably in contact with the outer peripheral surface of each rotation shaft. The plurality of developer conveying members include a first developer conveying member that supplies the developer to the developer carrying member, a second developer conveying member that collects the developer from the developer carrying member, and At the end of the first developer conveying member on the downstream side in the developer conveying direction. The elastic deformation amount with respect to the rotation axis of the location has been sealing member is smaller than the elastic deformation amount with respect to the rotation axis of the second developer conveying member of the developer conveyance direction downstream side end portion in the arranged sealing member It is characterized by comprising.

Since the first developer transport member supplies the developer to be transported to the developer carrying member, the developer amount decreases toward the downstream side in the developer transport direction. Therefore, the possibility that the developer collides with the seal member is low. On the other hand, since the second developer transport member collects the developer from the developer carrying member, the developer amount increases toward the downstream side in the developer transport direction. Therefore, there is a high possibility that the developer collides with the seal member. Therefore, compared to the seal member disposed at the downstream end of the second developer transport member in the developer transport direction, the first developer transport member is disposed at the downstream end of the developer transport direction. The seal member is not easily deteriorated. That is, even if the load applied to the rotating shaft of the first developer conveying member is lowered, the developer does not leak. Therefore, even when the rotation speed of the developer conveying member is increased in order to improve the developer conveying capability of the developer conveying member, the seal member prevents leakage of the developer from the end of the rotating shaft of the developer conveying member. High durability can be maintained.
In addition, by reducing the load load on the rotation shaft of the seal member arranged at the downstream end of the rotation shaft of the first developer conveyance member in the developer conveyance direction, the rotation shaft of the seal member and the developer conveyance member is reduced. And sliding friction is reduced. Therefore, even when the rotation speed of the developer conveying member is increased in order to improve the developer conveying ability of the developer conveying member, the load torque of the developer conveying member can be reduced and the temperature rise due to frictional heat can be suppressed. it can.
As described above, according to the present invention, even when the rotation speed of the developer transport member is increased in order to improve the developer transport capability of the developer transport member, the developer transport member is separated from the end of the rotation shaft of the developer transport member. While maintaining high durability of the seal member that prevents developer leakage, it is possible to suppress an increase in load torque and temperature.

1 is a schematic cross-sectional view showing an overall configuration of a color printer as an image forming apparatus according to an embodiment of the present invention. (A) is sectional drawing which shows one structural example of the inside of the developing device which has the some developer conveyance member used for the color printer which concerns on this embodiment, (b) is from X direction of Fig.2 (a). It is a side view which shows the positional relationship of the developer conveyance member in the internal structure of the developing device seen, (c) is a schematic diagram for demonstrating the mode of the circulation and conveyance of the developer in a developing device. (A), (b) and (c) are each a central part in the longitudinal direction of the developing device, showing another configuration example of the inside of the developing device having a plurality of developer conveying members used in the color printer according to this embodiment. It is sectional drawing of a longitudinal direction front side edge part and a longitudinal direction back side edge part. FIG. 4D is a side view showing the positional relationship of the developer conveying member in the internal configuration of the developing device as viewed from the direction of the arrow X in FIG. (A) is sectional drawing of the screw bearing which can be used for the support part of the collection | recovery screw in the image development apparatus of this embodiment, (b) is the state in which the collection | recovery screw shaft of the collection | recovery screw is assembled | attached to the screw bearing. FIG. (A) is a fragmentary sectional view which shows one structural example of the developer conveyance direction downstream edge part of the collection | recovery screw shaft of a collection | recovery screw, (b) is a developer conveyance direction downstream edge part of the supply screw axis | shaft of a supply screw. It is a fragmentary sectional view which shows one structural example. It is sectional drawing which shows the structural example of the screw bearing provided with the some sealing member. (A) is a fragmentary sectional view which shows one structural example of the developer conveyance direction downstream edge part of the collection | recovery screw shaft of a collection | recovery screw, (b) is a developer conveyance direction downstream edge part of the supply screw axis | shaft of a supply screw. It is a fragmentary sectional view which shows one structural example.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
Moreover, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

  FIG. 1 is a schematic cross-sectional view showing the overall configuration of a color printer as an image forming apparatus according to an embodiment of the present invention. The color printer of the present embodiment is a tandem printer that includes a plurality of sets of independent scanning optical systems and image carriers for the respective color components of black, cyan, yellow, and magenta. The color printer is an electrophotographic printer that performs multiplex printing in which toner images of respective colors formed on a plurality of image carriers are transferred in an overlapping manner on an intermediate transfer body as a transfer target. A color print can be obtained by transferring the superimposed toner image on the intermediate transfer body of the color printer onto a sheet as a recording medium (transfer body).

The color printer shown in FIG. 1 includes toner image forming units 100k, 100y, 100m, and 100c that form visible toner images of different colors (black, yellow, magenta, and cyan). The toner image forming units 100k, 100y, 100m, and 100c respectively include photosensitive drums 1k, 1y, 1m, and 1c as image carriers. Around the photoconductor drums 1k to 1c, charging devices 2k, 2y, 2m, 2c, scanning optical devices 3k, 3y, 3m, 3c, developing devices 4k, 4y, 4m, 4c, transfer devices 5k, 5y, 5m, respectively. 5c and cleaning devices 6k, 6y, 6m, and 6c are arranged in this order.
The charging units 2k to 2c are charging units, the scanning optical devices 3k to 3c are exposure units, the developing units 4k to 4c are developing units, the transfer units 5k to 5c are transfer units, and the cleaning units 6k to 6c. Is a cleaning means. The photosensitive drums 1k to 1c are each driven to rotate in the direction A in the drawing. Note that the subscripts k, y, m, and c attached to the reference numerals in FIG. 1 indicate devices corresponding to the respective colors of black, yellow, magenta, and cyan.

  In the color printer of this embodiment, the photosensitive drums 1k to 1c are uniformly charged by the chargers 2k to 2c, respectively, and image exposure is performed by the scanning optical devices 3k to 3c, and the photosensitive drums 1k to 1c are placed on the photosensitive drums 1k to 1c. An electrostatic latent image is formed. The electrostatic latent images on the photosensitive drums 1k to 1c are developed by the developing devices 4k to 4c, so that toner images of respective colors are formed. The toner images on the photosensitive drums 1k to 1c are superimposed and transferred onto the belt-like intermediate transfer body 7 by the transfer units 5k to 5c, respectively, so that the toner images are superimposed on the intermediate transfer body 7. A color image is formed. This color image is conveyed in the direction of arrow B in the figure by an intermediate transfer member 7 that is driven to rotate around a plurality of support rollers, and is collectively transferred to a sheet (not shown) at a predetermined secondary transfer position. The color image transferred to the paper is fixed by a fixing device (not shown) as fixing means. The cleaning devices 6k to 6c clean the residual toner remaining on the surfaces of the photosensitive drums 1k to 1c after the toner image is transferred.

  FIG. 2A is a cross-sectional view showing one configuration example of the inside of the developing device 4 having a plurality of developer conveying members used in the color printer according to the present embodiment. 2B is a side view showing the positional relationship of the developer conveying member in the internal configuration of the developing device 4 as viewed from the X direction in FIG. 2A, and FIG. It is a schematic diagram for demonstrating the mode of circulation and conveyance of the developing agent. Since the configuration and operation of the developing device 4 are the same for the developing devices 4k, 4y, 4m, and 4c of the respective colors, the subscripts k, y, m, and c is abbreviate | omitted and only the code | symbol is described (Hereafter, it is the same also in FIGS. 3-7). In addition, arrows S1, S2, and S3 in FIG. 2 indicate the transport directions of the developer transported by the plurality of developer transport members (screws 9, 10, and 11), respectively. In addition, arrows S4, S5, and S6 in FIG. 2 respectively indicate the developer at the longitudinal ends of the spaces (spaces V1, V2, and V3) in which the developer transport members (screws 9, 10, and 11) are disposed. The movement direction is shown.

  As shown in FIG. 2A, the developing device 4 includes a developing magnet roller 8 as a developer carrying member, a supply screw 9 as a first developer conveying member, and a recovery as a second developer conveying member. A screw 10 and a stirring screw 11 as a third developer conveying member are provided. The developing device 4 further includes a blade 12 as a developer regulating member and a case member 22 as a developer containing member.

The developing magnet roller 8 uses, for example, a non-magnetic sleeve that has a cylindrical shape and can be rotationally driven in the direction of the arrow in the figure, and a magnet member that is fixedly disposed in the sleeve and has N and S magnetic poles at predetermined positions. It is configured.
The blade 12 is a member that regulates the height (the amount of developer) of the developer magnetic brush that is carried by the developing magnet roller 8 and conveyed to the developing area E facing the photosensitive drum 1.
The case member 22 contains a two-component developer (hereinafter, referred to as “developer” in the embodiment) that includes toner of any one of black, cyan, yellow, and magenta and a carrier that is magnetic particles. . The developing magnet roller 8 is disposed in a space facing the photosensitive drum 1 in the case member 22 so that a part of the outer peripheral surface of the developing magnet roller 8 is exposed to the developing region E side.

The case member 22 includes a first space V1, a second space V2, and a third space V3 therein. A supply screw 9, a recovery screw 10, and a stirring screw 11 are disposed in each of the first space V1, the second space V2, and the third space V3.
The first space V1 in which the supply screw 9 is disposed and the second space V2 in which the recovery screw 10 is disposed are a first partition member that restricts the flow of the developer between the spaces V1 and V2. One partition wall 15a is provided. Furthermore, the second space V2 in which the recovery screw 10 is disposed and the third space V3 in which the stirring screw 11 is disposed are partition members that regulate the flow of the developer between the spaces V2 and V3. The second partition wall 15b is provided. Further, the third space V3 in which the stirring screw 11 is disposed and the first space V1 in which the supply screw 9 is disposed are partition members that restrict the flow of the developer between the spaces V3 and V1. The third partition wall 15c is provided.
In the illustrated example, these three partition walls 15 a, 15 b and 15 c are formed integrally with the case member 22.

The partition wall 15 (15a, 15b, 15c) has an opening for circulating and conveying the developer among the first space V1, the second space V2, and the third space V3.
For example, as shown in FIG. 2C, the first partition wall 15 a that partitions the first space V <b> 1 and the second space V <b> 2 is formed at the end on the downstream side in the developer transport direction by the supply screw 9. An opening N3 for discharging the developer from the space V1 and transferring it to the second space V2 is provided. Further, the opening N3 is formed at an end portion on the downstream side in the developer transport direction by the recovery screw 10. The developer is transferred from the downstream end portion of the supply screw 9 in the developer transport direction to the downstream end portion of the recovery screw 10 in the developer transport direction.
Further, the second partition wall 15b that partitions the second space V2 and the third space V3 discharges the developer from the second space V2 to the downstream end in the developer transport direction by the recovery screw 10. An opening N1 is provided for delivery to the third space V3. Further, the opening N <b> 1 is formed at the end on the upstream side in the developer transport direction by the stirring screw 11. The developer is transferred from the downstream end of the recovery screw 10 in the developer transport direction to the upstream end of the stirring screw 11 in the developer transport direction.
The third partition wall 15c that partitions the third space V3 and the first space V1 discharges the developer from the third space V3 to the downstream end in the developer transport direction by the stirring screw 11. An opening N2 is provided for delivery to the first space V1. Further, the opening N <b> 2 is formed at the end on the upstream side in the developer transport direction by the supply screw 9. The developer is transferred from the downstream end portion of the stirring screw 11 in the developer transport direction to the upstream end portion of the supply screw 9 in the developer transport direction.

Both end portions in the axial direction of the respective rotation shafts of the screws 9, 10, 11 and the developing magnet roller 8 are rotatably supported (axially supported) by the case member 22. Each of the screws 9, 10, 11 and the developing magnet roller 8 can be rotationally driven in the direction of the arrow in FIG. 2A by a rotational drive means having a drive source and a drive transmission mechanism (not shown). Each of the screws 9, 10, 11 stirs and conveys the developer in one axial direction of each rotating shaft (screw shaft 16, 17, 13).
The supply screw 9 stirs and conveys the developer along the supply screw shaft 16, which is its own rotation shaft, and supplies the developer to the developing magnet roller 8. Further, the recovery screw 10 agitates and conveys the developer along the recovery screw shaft 17 that is its own rotation shaft, and recovers the developer from the developing magnet roller 8. In addition, the agitation screw 11 conveys the developer along the agitation screw shaft 13 that is the rotation shaft of the agitation screw 11, and mixes the toner replenished from the replenishing port N4 with the existing developer and agitates.

  The screw shafts 16, 17, and 13 that are the rotation shafts of the three screws 9, 10, and 11 are provided in parallel to the rotation shaft of the photosensitive drum 1. Further, these three screws 9, 10, 11 are stirred at a position at a substantially intermediate height between the supply screw 9 on the upper side, the recovery screw 10 on the lower side, and the supply screw 9 and the recovery screw 10 in the vertical relationship. The screw 11 is arranged. The three screws 9, 10, 11 are rotated by a driving force from a driving source (not shown) to stir and convey the developer in the developing device 4. Thereby, the developer in the case member 22 is circulated and conveyed as shown by arrows S1, S2, S3, S4, S5, and S6 in the figure.

  As shown in FIG. 2A, the supply screw 9 supplies the developer to the developing magnet roller 8 while stirring and conveying the developer. The sleeve of the developing magnet roller 8 that rotates clockwise in the figure forms a magnetic brush by holding the developer supplied from the supply screw 9 by a magnetic force. The blade 12 regulates the height of the magnetic brush formed on the developing magnet roller 8 and returns the regulated developer to the supply screw 9. As shown in FIG. 2C, the developer that has not been supplied to the developing magnet roller 8 is stirred and conveyed to the downstream side (left side in the figure) of the supply screw 9 in the developer conveying direction. The developer agitated and transported downstream of the supply screw 9 in the developer transport direction moves due to staying, is discharged from the opening N3 as a developer delivery portion, and falls around the end of the recovery screw 10.

  Further, the developer whose toner density has been reduced by the development is collected from the developing magnet roller 8 by the agitating and conveying of the collecting screw 10 and conveyed to the downstream side of the collecting screw 10 in the developer conveying direction (the left side in FIG. 2C). Is done. The developer transported to the downstream side in the developer transport direction of the collection screw 10 moves to the stirring screw 11 obliquely upward through the opening N1 when the staying amount reaches a certain amount. The developer that has moved through the opening N1 is transported downstream (right side in FIG. 2C) by the agitating and conveying of the agitating screw 11 together with the toner replenished into the third space V3 from the replenishing port N4. It is conveyed to. The developer agitating and conveying by the agitating screw 11 was blocked by a partition 15 provided so as not to be mixed with the developer agitating and conveying other screws in the width of the image area where the photosensitive drum forms a latent image. Done in state.

  FIGS. 3A, 3 </ b> B, and 3 </ b> C are cross-sectional views illustrating another configuration example of the inside of the developing device 4 having a plurality of developer conveying members used in the color printer according to the present embodiment. The center part in the longitudinal direction, the front end part in the longitudinal direction, and the rear end part in the longitudinal direction of the developing device 4 are shown. FIG. 3D is a side view showing the positional relationship of the developer conveying member in the internal configuration of the developing device 4 as viewed from the direction of the arrow X in FIG. 3 (a) to 3 (d), the same parts as those in FIG.

  In the developing device 4 shown in FIG. 3, at least one screw (stirring screw) 11 </ b> A among the plurality of screws has a rotating shaft on the downstream side of the rotating shaft end portion 13 </ b> A on the upstream side in the developer transport direction. The end 13B is installed at a high position. Further, the developer stirred and conveyed by the other supply screw 9 and the recovery screw 10 is blocked by the partition wall 15 so that the developer is stirred and conveyed.

  The developer having a reduced toner concentration used for development in the development region E is recovered by stirring and transporting the recovery screw 10 and transported downstream of the recovery screw 10 in the developer transport direction. The developer transported downstream of the recovery screw 10 in the developer transport direction is retained at the downstream position of the developer screw 10, so that the rotation shaft on the upstream side of the developer transport direction of the stirring screw 11 </ b> A passing through the opening N <b> 1. It moves to the end portion 13A (left side in FIG. 3D). The developer that has moved to the rotating shaft end portion 13A of the stirring screw 11A is stirred and conveyed by the stirring screw 11A together with the toner replenished from the replenishing port N4, and the rotating shaft end portion 13B on the downstream side in the developer conveying direction (FIG. 3 ( d) It is conveyed to the periphery of the right side). The conveyance by the agitation screw 11A is performed in a state where it is blocked by the partition wall 15 so as not to be mixed with the developer that the other screws 9 and 10 are agitating and conveying. The developer conveyed to the periphery of the rotary shaft end portion 13B on the downstream side in the developer conveying direction of the stirring screw 11A passes through the opening N2 due to the stay at that position, and upstream in the developer conveying direction of the supply screw 9 located on the side. Move to the side. The developer moved to the supply screw 9 is supplied to the developing magnet roller 8.

  Next, with reference to FIG. 4, a description will be given of the support portion of the rotating shaft end portion of the screws 9, 10, 11 in the developing device 4 having the above-described configuration and the seal member provided on the support portion. In the following, the screw bearing of the recovery screw 10 among the three screws 9, 10, 11 will be described. However, the screw bearings of the supply screw 9 and the stirring screw 11 have the same configuration, and thus described. Is omitted.

FIG. 4A is a cross-sectional view of a screw bearing 21 (bearing portion) that can be used as a support portion of the recovery screw 10 in the developing device 4 having the above configuration. The screw bearing 21 includes a holder member 18 as a support member attached to the opening of the case member 22, a bearing member 19, and a seal member 20. As the holder member 18, a resin member such as POM (Polyoxymethylene) is often used and may also serve as a bearing. As the bearing member 19, a ball bearing or a plain bearing is used. As the seal member 20, an elastic member such as a rubber member or a sponge member is used. As an example, an oil seal manufactured by NOK Co., Ltd. may be used. The seal member 20 seals the gap between the outer peripheral surface of the screw shaft 17 and the support portion of the case member 22 that supports the screw shaft 17 by slidingly contacting the outer peripheral surface of the recovery screw shaft 17.
As the seal member 20, a seal member (for example, a G-type seal or an oil seal) having a lip portion 20a (elastic lip portion) that slidably contacts the outer peripheral surface of the screw shaft 17 can be used.

  FIG. 4B is a partial cross-sectional view showing a state in which the recovery screw shaft 17 that is the rotation shaft of the recovery screw 10 is assembled to the screw bearing 21. The inner diameter (hereinafter referred to as “sealing member inner diameter”) D of the seal member 20 is set smaller than the diameter (hereinafter referred to as “screw shaft diameter”) d of the recovery screw shaft 17 (d> D). The developer is prevented from leaking out of the case member 22 by fitting the seal member 20 into the outer peripheral surface of the recovery screw shaft 17 and elastically deforming the region (region H indicated by a dotted line in the figure). reference). If toner enters the sliding portion between the inner peripheral surface of the seal member 20 and the outer peripheral surface of the recovery screw shaft 17, the toner may be fixed and the recovery screw shaft 17 may be locked, and the developing device 4 may be damaged. Therefore, sealing by the seal member 20 is important.

The amount of elastic deformation of the seal member 20 with respect to the recovery screw shaft 17 is determined by the difference between the screw shaft diameter d and the seal member inner diameter D before installation (screw shaft diameter d−seal member inner diameter D). In other words, the elastic deformation amount is the amount of deformation of the seal member between the state where the recovery screw shaft 17 is not inserted into the seal member 20 and the state where it is inserted. As the elastic deformation amount of the seal member 20 increases, the sealing performance is improved (increased). However, as a disadvantage, the load torque when the recovery screw 10 is rotationally driven increases. Measurement of the amount of elastic deformation and load torque is a measure for evaluating the sealing performance.
In order to improve the sealing performance between the seal member and the screw shaft, for example, the elastic deformation amount of the seal member with respect to the screw shaft is increased, the contact area between the seal member and the screw shaft is increased, or the number of seal members is increased. Or just increase it. By doing in this way, the load load (load torque, contact pressure, frictional force, or sliding resistance) which the sealing member 20 gives to the collection | recovery screw axis | shaft 17 can be raised, and a sealing performance can be improved as a result.
For example, when the seal member 20 having the elastic lip portion 20a is used, the contact area of the elastic lip portion 20a can be increased by increasing the amount of elastic deformation of the seal member 20, and the recovery screw shaft of the seal member 20 can be increased. The load applied to 17 can be increased. Conversely, in order to reduce the load applied to the recovery screw shaft 17 of the seal member 20, it is only necessary to reduce the amount of elastic deformation of the seal member 20 and reduce the contact area of the elastic lip portion 20a.

Next, with reference to FIGS. 5 to 7, the relationship between the sealing properties of the sealing members provided on the support portions at the ends of the rotating shafts of the screws 9 and 10 in the developing device 4 having the above-described configuration will be described.
Embodiment 1
FIG. 5A is a partial cross-sectional view illustrating a configuration example of the downstream end portion of the recovery screw shaft 17 of the recovery screw 10 in the developer conveying direction, and FIG. 5B is a view of the supply screw shaft 16 of the supply screw 9. FIG. 6 is a partial cross-sectional view illustrating a configuration example of a downstream end portion in a developer transport direction. In addition, illustration of the screw blade | wing of the screws 9 and 10 is abbreviate | omitted in FIG. In addition, arrows S1 and S2 in the figure indicate the transport direction of the developer. In the present embodiment, the seal member 20 gives the screw shaft the elastic deformation amount of the seal member 20 or the contact area of the seal member 20 with respect to the screw shaft between the supply screw shaft 16 and the recovery screw shaft 17. It is characterized in that the load weight is increased or decreased.
In the configuration shown in FIG. 5A, the screw shaft diameter, which is the diameter of the recovery screw shaft 17 on the downstream side in the developer conveying direction of the recovery screw 10, is d1. On the other hand, in the configuration shown in FIG. 5B, a part of the screw shaft diameter of the supply screw shaft 16 at the downstream side in the developer conveying direction of the supply screw 9 is in contact with the seal member 20 of the screw bearing 21. Reduced to d2. That is, the condition (d1> d2 (> D)) that the screw shaft diameter d1 on the downstream side in the developer conveyance direction of the recovery screw 10 is larger than the screw shaft diameter d2 on the downstream side in the developer conveyance direction of the supply screw 9 is satisfied. With this configuration, “d1-D> d2-D” is satisfied.
As a result, the elastic deformation amount of the seal member 20 at the downstream end of the supply screw shaft 16 of the supply screw 9 in the developer conveyance direction is transferred to the downstream end of the recovery screw shaft 17 of the recovery screw 10 in the developer conveyance direction. It is smaller than that. In other words, the load applied to the supply screw shaft 16 of the seal member 20 disposed at the downstream end of the supply screw 9 in the developer conveyance direction is used as the seal disposed at the downstream end of the recovery screw 10 in the developer conveyance direction. The member 20 is configured to be lower than the load applied to the recovery screw shaft 17. By adopting such a configuration, the durability of the seal member 20 at the end of the recovery screw shaft 17 and the supply screw shaft 16 on the downstream side in the developer transport direction is ensured, and a problem due to a temperature rise with a low load torque is ensured. It is possible to realize a developing device 4 that is not present.

That is, the conveying ability in the axial direction of the screw is larger than the conveying ability in other directions (for example, the radial direction and the circumferential direction of the screw shaft). Therefore, at the downstream end of the screw shaft in the developer conveyance direction, the developer advances toward the seal member provided on the screw shaft bearing and collides with the seal member. The collision between the developer and the seal member leads to deterioration of the seal member. In particular, if the developer enters between the seal member and the screw shaft at the time of the developer collision, the developer acts as an abrasive, wears the seal member and / or the screw shaft, and the sealing performance is rapidly deteriorated. May progress.
In the developing device 4 according to this embodiment, the blade 12 is disposed above the developing magnet roller 8. In such a developing device 4, the developer is supplied from the supply screw 9 to the developing magnet roller 8, and the amount of developer is regulated by the blade 12. The developer on the developing magnet roller 8 is converted into a toner image on the photosensitive drum 1, separated from the developing magnet roller 8, and collected by a collecting screw 10 disposed below the supply screw 9.

In the supply screw 9, since the developer is supplied to the developing magnet roller 8, the amount of developer on the downstream side in the developer transport direction is small. Further, the developer that has moved to the downstream side in the developer transport direction of the supply screw 9 falls to the recovery screw 10 disposed below through the opening N3. Therefore, on the downstream side of the supply screw 9 in the developer transport direction, the possibility that the developer collides with the seal member 20 is low, and the seal member 20 is hardly deteriorated.
On the other hand, the recovery screw 10 recovers the developer separated from the developing magnet roller 8, so that the developer amount increases toward the downstream side in the developer transport direction. Therefore, on the downstream side of the recovery screw 10 in the developer transport direction, the developer is highly likely to collide with the seal member 20, and the seal member 20 is likely to deteriorate.
Therefore, the sealing performance of the seal member 20 disposed at the downstream end of the supply screw 9 in the developer transport direction is higher than that of the seal member 20 disposed at the downstream end of the recovery screw 10 in the developer transport direction. Even if it is made smaller, the developer does not leak.

Therefore, even when the rotational speed of the screws 9 and 10 is increased in order to improve the developer conveying capability of the screws 9 and 10, the seal member 20 that prevents the leakage of the developer from the ends of the screw shafts 16 and 17 is provided. High durability can be maintained.
Moreover, the sliding friction between the seal member 20 and the supply screw shaft 16 is reduced by reducing the sealing performance of the seal member 20 disposed at the downstream end of the supply screw shaft 16 of the supply screw 9 in the developer transport direction. Is done. Therefore, even when the rotational speed of the screws 9 and 10 is increased in order to improve the developer conveying capability of the screws 9 and 10, the load torque of the supply screw 9 can be reduced and the temperature rise due to frictional heat can be suppressed. .
Therefore, even when the rotational speed of the screws 9 and 10 is increased in order to improve the developer conveying capability of the screws 9 and 10, the screw shafts 16 and 17 of the screws 9 and 10 are separated from the end on the downstream side in the developer conveying direction. The rise in load torque and temperature can be suppressed while maintaining the high durability of the seal member 20 that prevents the leakage of the developer.

[Embodiment 2]
FIG. 6 is a cross-sectional view illustrating a configuration example of a screw bearing 21 including a plurality of seal members 20A and 20B. As shown in FIG. 6, the sealing performance can be improved by increasing the number of the sealing members. That is, by increasing / decreasing the number of seal members, the total area of the seal members in contact with the screw shaft can be increased / decreased, and the load applied by the seal member to the screw shaft can be increased / decreased.
That is, in the present embodiment, the seal member 20 gives the screw shaft by making the number of the seal members 20 or the total contact area of the seal member 20 with respect to the screw shaft different between the supply screw shaft 16 and the recovery screw shaft 17. The load weight is increased or decreased.

FIG. 7A is a partial cross-sectional view illustrating a configuration example of the downstream end portion of the recovery screw shaft 17 of the recovery screw 10 in the developer transport direction, and FIG. 7B is a partial cross-sectional view of the supply screw shaft 16 of the supply screw 9. FIG. 6 is a partial cross-sectional view illustrating a configuration example of a downstream end portion in a developer transport direction. In addition, illustration of the screw blade | wing of the screws 9 and 10 is abbreviate | omitted in FIG. In addition, arrows S1 and S2 in the figure indicate the transport direction of the developer.
In the configuration shown in FIG. 7B, there is one seal member 20 of the screw bearing 21 on the downstream side in the developer transport direction of the supply screw 9, whereas in the configuration shown in FIG. Two seal members 20A and 20B are arranged on the screw bearing 21 on the downstream side in the conveying direction. With such a configuration, it is possible to realize a developing device that is low in load and free from problems due to temperature rise while ensuring the durability of the seal member 20.

  In the developing device 4 that circulates the developer in one direction by the configuration shown in FIGS. 4 to 7, even when the rotational speed of the screws 9, 10, 11 that are developer conveying members is increased, High durability can be maintained by preventing leakage of the developer. At the same time, an increase in load torque can be suppressed to reduce costs and save energy, and a stable image can be formed.

The developing device 4 described in the present embodiment can be implemented by being mounted on a process cartridge configured to be detachable from the main body of the color printer. That is, the process cartridge configured to be detachable from the main body of the color printer has a photosensitive drum 1 for developing an electrostatic latent image carried by a developer supplied from the developing device 4 in addition to the developing device 4. In addition, at least one of the charger 2 that uniformly charges the surface of the photoconductor 1 and the cleaning device 6 that cleans the surface of the photoconductor drum 1 may be integrally held.
In the present embodiment, the case of the developing device 4 including three screws (a supply screw 9, a recovery screw 10, and a stirring screw 11) as a developer conveying member has been described. In addition to the above, the present invention can be similarly applied to a developing device including two developer transport members that transport the developer in one direction. Further, the present invention can be similarly applied to a developing device including four or more developer conveying members that convey a developer in one direction.
Further, in the present embodiment, the case of the developing device using the two-component developer has been described. However, in the present invention, the developing device using the one-component developer includes a developer transport member that transports the developer in one direction. It can be similarly applied to.

  Hereinafter, modifications of the embodiment will be described. In each said form, the sealing performance of the sealing member 20 arrange | positioned in the developer conveyance direction downstream of the supply screw shaft 16 of the supply screw 9 has been arrange | positioned in the developer conveyance direction downstream of the collection | recovery screw shaft 17 of the collection | recovery screw 10. It was set to be lower than the sealing performance of the sealing member 20. Similar to the above embodiment, the following relationship may be set and executed.

[Modification 1]
The sealing performance of the seal member 20 disposed on the upstream side in the developer transport direction of the supply screw shaft 16 and / or the recovery screw shaft 17 is the seal of the seal member 20 disposed on the downstream side of the recovery screw shaft 17 in the developer transport direction. You may set so that it may become low compared with property.
That is, as described above, at the downstream end portion of the screw shaft in the developer transport direction, the developer advances toward the seal member provided on the screw shaft bearing and collides with the seal member. The collision between the developer and the seal member leads to deterioration of the seal member. On the other hand, since the developer is transported in the direction opposite to the direction in which the seal member is disposed at the upstream end portion in the developer transport direction of the screw shaft, the possibility that the developer collides with the seal member is low. Therefore, even if the sealing performance between the seal member on the upstream side in the developer transport direction and the screw shaft is lower than that on the downstream side in the developer transport direction of the screw shaft, the developer enters between the seal member and the screw shaft. The fear is low, and the seal member is unlikely to deteriorate.
From the above circumstances, the sealing performance of the seal member 20 arranged at the upstream end of at least one developer transport direction of the screw shafts 16 and 17 is determined as the end of the recovery screw shaft 17 on the downstream side in the developer transport direction. Even if it is lower than the sealing performance of the sealing member 20 arranged in the above, the developer does not leak.
Therefore, even when the rotational speed of the screws 9 and 10 is increased in order to improve the developer conveying capability of the screws 9 and 10, the height of the seal member that prevents leakage of the developer from both ends of the screw shafts 16 and 17 is increased. An increase in load torque and temperature can be suppressed while maintaining durability.

[Modification 2]
Alternatively, as in the first modification, the sealing property of the seal member 20 disposed on the upstream side in the developer conveyance direction of the stirring screw shaft 13 is the seal disposed on the downstream side in the developer conveyance direction of the recovery screw shaft 17 of the recovery screw 10. You may implement by setting so that it may become low compared with the sealing performance of the member 20. Even if it sets in this way, the same effect as modification 1 can be acquired for the same reason as modification 1.

[Modification 3]
The sealing performance of the seal member 20 disposed on the upstream side of the supply screw shaft 16 in the developer conveying direction of the supply screw 9 is lower than the sealing performance of the seal member 20 disposed on the downstream side of the supply screw shaft 16 in the developer conveyance direction. You may set so that.
Similarly, the sealing performance of the seal member 20 disposed on the upstream side in the developer conveyance direction of the stirring screw shaft 13 of the stirring screw 11 is changed to the sealing performance of the seal member 20 disposed on the downstream side in the developer conveyance direction of the stirring screw shaft 13. You may set so that it may become low compared.
That is, as described above, at the downstream end portion of the screw shaft in the developer transport direction, the developer advances toward the seal member provided on the screw shaft bearing and collides with the seal member. The collision between the developer and the seal member leads to deterioration of the seal member. On the other hand, since the developer is transported in the direction opposite to the direction in which the seal member is disposed at the upstream end portion in the developer transport direction of the screw shaft, the possibility that the developer collides with the seal member is low. Therefore, even if the sealing performance between the seal member on the upstream side in the developer transport direction and the screw shaft is lower than that on the downstream side in the developer transport direction of the screw shaft, the developer enters between the seal member and the screw shaft. The fear is low, and the seal member is unlikely to deteriorate.
From the above circumstances, the sealing performance of the seal member 20 disposed at the upstream end of the screw shafts 16 and 13 in the developer transport direction is disposed at the downstream end of the screw shafts 16 and 13 in the developer transport direction. Even if it is lower than the sealing property of the seal member 20, the developer does not leak.
Therefore, even when the rotational speed of the screws 9 and 11 is increased in order to improve the developer conveying capability of the screws 9 and 11, the height of the seal member that prevents the leakage of the developer from both ends of the screw shafts 16 and 13 is increased. An increase in load torque and temperature can be suppressed while maintaining durability.
As long as there is no contradiction, the relationship of the sealing performance of the sealing members provided at the end portions of the screw shafts shown in the embodiment or the modification may be performed simultaneously.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Charger, 3 ... Scanning optical device, 4 ... Developing device, 5 ... Transfer device, 6 ... Cleaning device, 7 ... Intermediate transfer body, 8 ... Developing magnet roller, 9 ... Supply screw, 10 DESCRIPTION OF SYMBOLS ... Recovery screw, 11 ... Stir screw, 12 ... Blade, 13 ... Stir screw shaft, 13A, 13B ... End of rotating shaft, 15a ... First partition, 15b ... Second partition, 15c ... Third partition, 16 DESCRIPTION OF SYMBOLS ... Supply screw shaft, 17 ... Collection | recovery screw shaft, 18 ... Holder member, 19 ... Bearing member, 20 ... Seal member, 21 ... Screw bearing, 22 ... Case member, 100 ... Toner image formation unit, E ... Development area, N1, N2, N3 ... opening, N4 ... supply port, V1 ... first space, V2 ... second space, V3 ... third space

Japanese Patent Laid-Open No. 05-333691 Japanese Patent Laid-Open No. 11-174810

Claims (10)

A developer accommodating member for accommodating the developer;
A developer carrying member that carries the developer contained in the developer containing member and conveys the developer to a developing region facing the image carrier;
A plurality of developer conveying members that are rotatably supported at both axial ends of the rotating shaft by bearing portions provided in the developer containing member, and convey the developer contained in the developer containing member in the axial direction; ,
A developing device comprising: each rotating shaft of the plurality of developer conveying members; and a seal member that slidably contacts the outer peripheral surface of each rotating shaft ;
The plurality of developer conveying members include a first developer conveying member that supplies a developer to the developer carrying member, and a second developer conveying member that collects the developer from the developer carrying member. Including
The amount of elastic deformation of the seal member disposed at the downstream end of the first developer conveying member with respect to the rotation axis is determined on the downstream side of the developer conveying direction of the second developer conveying member. A developing device characterized in that it is configured to be smaller than an elastic deformation amount of the seal member disposed at the end with respect to the rotation shaft. The amount of elastic deformation of each of the first developer transport member and / or the seal member disposed at the upstream end of the second developer transport member in the developer transport direction with respect to each of the rotation shafts is determined by the second the developing device according to claim 1 in which the characterized by being made smaller than the elastic deformation amount with respect to the rotation axis of the deployed seal member to the end of the current image agent conveyance direction downstream side of the developer conveying member. The developer transport member disposed in a third space different from the first space in which the first developer transport member is disposed and the second space in which the second developer transport member is disposed. A third developer conveying member that mixes the developer collected by the second developer conveying member and the toner replenished in the third space and conveys the mixture while stirring;
The amount of elastic deformation of the seal member disposed at the upstream end of the third developer conveying member in the developer conveying direction with respect to the rotation shaft is determined on the downstream side of the developer conveying direction of the second developer conveying member. 3. The developing device according to claim 1 , wherein the developing device is configured to be smaller than an elastic deformation amount of the seal member disposed at an end portion with respect to the rotation shaft.   A developer accommodating member for accommodating the developer;
  A developer carrying member that carries the developer contained in the developer containing member and conveys the developer to a developing region facing the image carrier;
  A plurality of developer conveying members that are rotatably supported at both axial ends of the rotating shaft by bearing portions provided in the developer containing member, and convey the developer contained in the developer containing member in the axial direction; ,
  A developing device comprising: each rotating shaft of the plurality of developer conveying members; and a seal member that slidably contacts the outer peripheral surface of each rotating shaft;
  The plurality of developer conveying members include a first developer conveying member that supplies a developer to the developer carrying member, and a second developer conveying member that collects the developer from the developer carrying member. Including
  The contact area of the seal member disposed at the downstream end of the first developer transport member with respect to the developer transport direction is defined as the downstream end of the second developer transport member with respect to the developer transport direction. A developing device characterized in that it is configured to be smaller than a contact area of the seal member disposed in the portion with respect to the rotating shaft.   The contact area of each of the first developer transport member and / or the seal member disposed at the upstream end in the developer transport direction of the second developer transport member with respect to each of the rotation shafts is defined as the second developer transport member. 5. The developing device according to claim 4, wherein the developing device is configured to have a smaller contact area with respect to the rotation shaft of a seal member disposed at an end of the developer transport member on the downstream side in the developer transport direction.   The developer transport member disposed in a third space different from the first space in which the first developer transport member is disposed and the second space in which the second developer transport member is disposed. A third developer conveying member that mixes the developer collected by the second developer conveying member and the toner replenished in the third space and conveys the mixture while stirring;
  The contact area of the seal member disposed at the upstream end of the third developer conveying member in the developer conveying direction with respect to the rotation shaft is defined as the downstream end of the second developer conveying member in the developer conveying direction. The developing device according to claim 4, wherein the developing device is configured to be smaller than a contact area of the seal member disposed in the portion with respect to the rotation shaft. A second partition member that restricts the passage of the developer between the second space and the third space;
7. The development according to claim 3, further comprising a second opening provided in the second partition member for transporting the developer from the second space to the third space. 8. apparatus.   A first partition member for restricting the flow of the developer between the first space in which the first developer transport member is disposed and the second space in which the second developer transport member is disposed; Prepared,
  The said 1st partition member has a 1st opening part which conveys a developer to the said 2nd space from the said 1st space, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The developing device according to 1.   At least one of an image carrier, a charging unit for uniformly charging the image carrier, a cleaning unit for cleaning the image carrier, and a developing unit for developing an electrostatic latent image formed on the image carrier A process cartridge comprising: the developing device according to claim 1, wherein the process cartridge is configured to be detachable from the image forming apparatus.   An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 9.

Images