JP6112298B2 - Developing device, process unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device, a process unit including the developing device, and an image forming apparatus.

  2. Description of the Related Art In electrophotographic image forming apparatuses such as copying machines, printers, facsimiles, and complex machines thereof, a developing device that visualizes a latent image formed on a photoconductor as an image carrier is provided.

  As shown in FIG. 11, the developing device includes a developing roller 410 carrying toner as a developer on the surface, a supply roller 420 that supplies toner to the developing roller 410, and a uniform thickness of toner on the developing roller 410. The restriction blade 430 and the like for restricting the height are basic constituent elements.

12 is a cross-sectional view taken along the line AA in FIG.
As shown in FIG. 12, the supply roller 420 generally has a core material 420a and an elastic layer 420c disposed on the outer periphery of the core material 420a via an adhesive layer 420b. The elastic layer 420c is formed of foamed polyurethane or the like. The elastic layer 420c holds toner in the developing device and supplies the toner to the developing roller 401.

  The basic operation of the developing device will be described. First, the toner contained in the developing device is frictionally charged by the sliding of both rollers at the contact portion (nip portion) between the supply roller 420 and the developing roller 410 and developed. Supplied to the surface of row 410. Next, the toner carried on the surface of the developing roller 410 is regulated to a uniform thickness by the regulating blade 430 and charged. In the developing area between the photosensitive member 200 and the developing roller 410, the toner on the developing roller 410 is transferred to the latent image on the photosensitive member 200 by the developing electric field, and the latent image is visualized as a toner image. In this way, a desired image can be obtained by a good transfer of toner from the supply roller 420 to the developing roller 410 and from the developing roller 410 to the photosensitive member 200.

  On the other hand, the toner remaining on the developing roller 410 without being transferred onto the photoreceptor 200 is scraped off by the supply roller 420 when it is conveyed again to the contact portion (nip portion) between the supply roller 420 and the development roller 410. And recovered.

  As shown in FIG. 12, the developing device is provided with end seals 500 that seal at the positions of both end portions in the axial direction of the developing roller 410. The end seal 500 seals between the developing roller 410 and the case (developing container) 400 of the developing device, thereby suppressing toner leakage from the end of the developing roller 410.

  Here, paying attention to the arrangement of the end seal 500 and the supply roller 420, the supply roller 420 is disposed in a non-contact manner with respect to the end seal 500 via the gap S in the axial direction. Thus, by disposing the supply roller 420 in a non-contact manner with respect to the end seal 500, friction due to the end of the supply roller 420 (elastic layer 420c) coming into contact with the end seal 500 does not occur. Thus, an increase in rotational torque and heat generation due to friction are prevented (for example, see Patent Document 1).

  However, as shown in FIG. 12, when the supply roller 420 is disposed with respect to the end seal 500 via the gap S, the toner component is present in the end region J on the developing roller 401 corresponding to the gap S. However, there is a problem that filming occurs on the developing roller in the form of a film, so-called filming occurs. This is because, in the end region J, the supply roller 420 is not in contact with the developing roller 401, and thus the toner collecting function on the developing roller 401 by the supply roller 420 cannot be obtained. That is, even if the toner in the developing device adheres to the end region J on the developing roller 401, the toner is not collected by the supply roller 420, so the adhered toner continues to exist on the developing roller 410 and eventually forms a film. Filming occurs due to sticking.

  As the filming progresses, the toner charging function of the developing roller decreases, the electrostatic adhesion force of the toner to the developing roller weakens, and the toner easily moves from the developing roller to the photoreceptor. As a result, a phenomenon called background smearing occurs in which toner adheres to a blank paper portion (non-image forming portion) on the edge side of the paper.

  In particular, in the configuration in which the developing roller is shortened in the axial direction and the size is reduced, the difference between the end region J where the filming may occur and the maximum sheet passing region is small. Only by causing skew (skew), background smearing is likely to occur on the edge side of the paper.

  In view of such circumstances, the present invention intends to provide a developing device capable of preventing filming on the end side of a developer carrying member, a process unit including the developing device, and an image forming apparatus. It is.

In order to solve the above-described problems, the present invention provides a developer carrying member that carries a developer on the surface, and a developer supply that supplies the developer onto the developer carrying member in contact with the surface of the developer carrying member. Members,
In the developing device, comprising: an end seal contacting the end side of the developer carrying member, wherein the developer supply member includes a core material and an elastic layer bonded to an outer periphery of the core material. Non-adhesive non-adhering to the core material over a predetermined range from the end of the elastic layer contacting the end seal with the end of the elastic layer of the agent supply member in contact with the end seal A region is provided.

  According to the present invention, it is possible to prevent the occurrence of filming on the end portion side of the developer carrying member by bringing the end portion of the developer supply member into contact with the end seal.

  Furthermore, according to the present invention, the developer supply member and the end seal come into contact with each other by providing the non-adhesive region over a predetermined range from the end of the developer supply member that contacts the end seal of the elastic layer. The stress generated by this can be dispersed in the axial direction of the elastic layer. As a result, it is possible to reduce a load caused by friction generated between the developer supply member and the end seal.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a developing device and a toner cartridge. It is BB sectional drawing of FIG. It is sectional drawing which shows the axial direction length of a non-bonding area | region. It is a figure which shows the test result done in order to confirm the effect of this invention. It is sectional drawing of the developing device which concerns on other embodiment of this invention. It is a perspective view of a supply roller provided with a low friction member. It is the figure which looked at the supply roller provided with the low friction member from the axial direction. It is a figure which shows embodiment which provided the edge part exposure means which exposes the both ends part of a photoconductor. It is a figure which shows the structure of a comparative example. It is a figure which shows the structure of the conventional image development apparatus. It is AA sectional drawing of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description is omitted.

  FIG. 1 is a schematic configuration diagram of a printer as an image forming apparatus according to an embodiment of the present invention. First, the overall configuration and operation of the printer will be described with reference to FIG.

  As shown in FIG. 1, images of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to color separation components of a color image are formed on the image forming apparatus main body 100. Four process units 1Y, 1M, 1C, and 1Bk as image forming units to be attached are detachably mounted. Each of the process units 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoreceptor 2 as a latent image carrier that carries a latent image on the surface, a charging roller 3 as a charging unit that charges the surface of the photoreceptor 2, A developing device 4 as a developing unit that visualizes the latent image on the photoconductor 2 and a cleaning device 5 as a cleaning unit for cleaning the surface of the photoconductor 2 are provided. In FIG. 1, only the photoconductor 2, the charging roller 3, the developing device 4, and the cleaning device 5 included in the process unit 1 </ b> Y for yellow image are denoted by reference numerals. In the other process units 1 </ b> M, 1 </ b> C, and 1 </ b> Bk, The reference numerals are omitted.

  At the top of each developing device 4, toner cartridges 6Y, 6M, 6C, 6Bk as developer supply containers are detachably mounted. The toner cartridges 6Y, 6M, 6C, and 6Bk contain toners (developers) of colors used for the corresponding process units 1Y, 1M, 1C, and 1Bk, respectively.

  An exposure device 7 serving as a latent image forming unit that forms a latent image on the surface of each photoconductor 2 is disposed on the upper portion of the image forming apparatus main body 100. The exposure device 7 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoreceptor 2 with laser light based on image data.

  A transfer device 8 is disposed below each photoconductor 2. The transfer device 8 includes an intermediate transfer belt 9 composed of an endless belt as a transfer member, a driving roller 10 and a driven roller 11 that stretch the intermediate transfer belt 9, and four primary transfer rollers 12 as primary transfer means. And a secondary transfer roller 13 as a secondary transfer means. The drive roller 10 is rotated counterclockwise in the figure by a drive source (not shown), whereby the intermediate transfer belt 9 runs (rotates) in the direction indicated by the arrow in the figure. .

  The four primary transfer rollers 12 are in contact with the photoreceptor 2 via the intermediate transfer belt 9. As a result, the respective photoreceptors 2 and the intermediate transfer belt 9 are in contact with each other, and a primary transfer nip for transferring a toner image is formed between them. Each primary transfer roller 12 is connected to a power source (not shown) so that a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the primary transfer roller 12.

  The secondary transfer roller 13 is in contact with the driving roller 10 via the intermediate transfer belt 9. As a result, a secondary transfer nip for transferring a toner image is formed between the secondary transfer roller 13 and the intermediate transfer belt 9. Similarly to the primary transfer roller 12, the secondary transfer roller 13 is connected to a power source (not shown), and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the secondary transfer roller 13. It has come to be.

  Further, a belt cleaning device 14 for cleaning the surface of the intermediate transfer belt 9 is provided at the right side of the drawing of the transfer device 8. The belt cleaning device 14 includes a cleaning blade 15 that contacts the outer peripheral surface of the intermediate transfer belt 9, a cleaning backup roller 16 that supports the tip of the cleaning blade 15 from the inner peripheral surface side of the intermediate transfer belt 9, and the intermediate transfer belt 9. A transport coil 17 for transporting the removed toner. A waste toner container 18 is provided below the transfer device 8, and a waste toner transfer hose (not shown) extending from the belt cleaning device 14 is connected to the inlet of the waste toner container 18. .

  A toner mark sensor 19 is provided at the left side of the drawing of the transfer device 8. The toner mark sensor 19 is a reflection type optical sensor, and the toner mark sensor 19 detects the toner adhesion amount and position on the intermediate transfer belt 9 to adjust the density and position of the toner image.

  A lower portion of the image forming apparatus main body 100 is provided with a paper feed tray 20 that stores paper P as a recording medium, a paper feed roller 21 that feeds the paper P from the paper feed tray 20, and the like. In addition to plain paper, the recording medium includes cardboard, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, and the like.

  In the image forming apparatus main body 100, a conveyance path R is disposed for discharging the paper P from the paper feed tray 20 through the secondary transfer nip to the outside of the apparatus. In the transport path R, a registration roller pair 22 that is a timing roller pair is provided between the position of the paper feed roller 21 and the position of the secondary transfer roller 13. In the transport path R, a fixing device 23 for fixing the unfixed image transferred onto the paper P is provided downstream of the position of the secondary transfer roller 13 in the paper transport direction. Further, at the end of the conveyance path R, a paper discharge roller pair 24 for discharging the paper P to the outside of the apparatus is provided, and the paper P discharged outside the apparatus is stocked on the upper surface portion of the image forming apparatus main body 100. A paper discharge tray 25 is provided.

The image forming apparatus operates as follows.
When the image forming operation is started, the photosensitive members 2 of the process units 1Y, 1M, 1C, and 1Bk are rotated in the clockwise direction in FIG. 1, and the surface of each photosensitive member 2 is made to have a predetermined polarity by the charging roller 3. It is charged like this. Next, an electrostatic latent image is formed on the charged surface of each photoconductor 2 by exposure from the exposure device 7 based on image information from a reading device or a computer (not shown). At this time, the image information to be exposed on each photoconductor 2 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. As the electrostatic latent image formed on the photosensitive member 2 is supplied with toner by each developing device 4, the electrostatic latent image is visualized (visualized) as a toner image.

  When the image forming operation is started, the driving roller 10 that stretches the intermediate transfer belt 9 is rotationally driven, so that the intermediate transfer belt 9 runs in the direction of the arrow in the figure. The primary transfer roller 12 is applied with a constant voltage having a polarity opposite to the toner charging polarity or a voltage controlled by a constant current, whereby the primary transfer nip between each primary transfer roller 12 and each photoreceptor 2 is applied. A transfer electric field is formed.

  Thereafter, when each color toner image on the photoconductor 2 reaches the primary transfer nip as the photoconductor 2 rotates, the toner image on each photoconductor 2 is generated by the transfer electric field formed in the primary transfer nip. Are sequentially superimposed and transferred onto the intermediate transfer belt 9. Thus, a full-color toner image is carried on the surface of the intermediate transfer belt 9. Further, the toner on each photoconductor 2 that could not be transferred to the intermediate transfer belt 9 is removed by the cleaning device 5.

  In the lower part of the image forming apparatus, the paper feed roller 21 starts to rotate, and the paper P is sent out from the paper feed tray 20 to the transport path R. The sheet P sent to the transport path R is timed by the registration roller pair 22 and sent to the secondary transfer nip between the secondary transfer roller 13 and the drive roller 10. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 9 is applied to the secondary transfer roller 13, thereby forming a transfer electric field in the secondary transfer nip.

  Thereafter, when the toner image on the intermediate transfer belt 9 reaches the secondary transfer nip as the intermediate transfer belt 9 circulates, the transfer electric field formed in the secondary transfer nip causes a transfer on the intermediate transfer belt 9. The toner images are transferred onto the paper P all at once. At this time, the residual toner on the intermediate transfer belt 9 that could not be transferred onto the paper P is removed by the cleaning blade 15 of the belt cleaning device 14, and the removed toner is transferred to the waste toner container 18 by the conveying coil 17. Transported and collected.

  Thereafter, the paper P is conveyed to the fixing device 23, and the toner image on the paper P is fixed to the paper P by the fixing device 23. Then, the paper P is discharged out of the apparatus by the paper discharge roller pair 24 and stocked on the paper discharge tray 25.

  The above description is an image forming operation when a full-color image is formed on a recording medium. A single color image is formed using any one of the four process units 1Y, 1M, 1C, and 1Bk, and 2 Two or three process units can be used to form a two or three color image.

Hereinafter, the configuration of the developing device and the toner cartridge will be described in detail.
The developing devices 4 and the toner cartridges 6Y, 6M, 6C, and 6Bk have substantially the same configuration except that they store different color toners. A description will be given of the configuration of one developing device and a toner cartridge, omitting the symbols (Y, M, C, Bk) indicating identification.

FIG. 2 is a schematic sectional view of the developing device and the toner cartridge.
As shown in FIG. 2, a stirring paddle 31 that is a stirring member that stirs toner and a transport screw 32 that is a transport member that transports toner are provided in the container body 30 of the toner cartridge 6. Further, the container body 30 is provided with a discharge port 33 connected to a supply port 46 provided in the developing device 4 in a state where the toner cartridge 6 is mounted on the upper portion of the developing device 4. When the transport screw 32 rotates, the toner in the container body 30 is transported in the axial direction, and the toner is supplied from the discharge port 33 into the developing device 4. The conveying screw 32 can be connected to a driving unit (not shown) provided in the image forming apparatus main body by a known means such as a clutch in a state where the toner cartridge 6 is mounted. The toner replenishment amount can be controlled based on the drive time of the drive unit. For example, the driving time may be varied in accordance with the change in toner fluidity depending on the color of the toner or the temperature and humidity environment.

  The developing device 4 includes a developing container 40 in which a developer containing portion 47 for containing toner is formed, a developing roller 41 as a developer carrying member for carrying toner, and a developer for supplying toner to the developing roller 41. A supply roller 42 as a supply member, a regulation blade 43 as a regulation member that regulates the thickness of toner carried on the developing roller 41, a conveyance screw 44 as a conveyance member that conveys toner, and agitating the toner An agitator 45 as a stirring member is provided.

  When the image forming operation is started, the toner in the developer container 47 is agitated by the rotating agitator 45, and the toner is supplied to the supply roller 42 by the rotating conveying screw 44. As the supply roller 42 rotates, the toner supplied to the supply roller 42 is supplied to the development roller 41 at the nip when the supply roller 42 and the development roller 41 come into contact with each other. The toner supplied onto the developing roller 41 moves with the rotation of the developing roller 41, and has a uniform thickness by the regulating blade 43 when passing through the nip portion where the regulating blade 43 contacts the developing roller 41. Regulated by When the toner on the developing roller 41 is conveyed to a position (development area) facing the photoreceptor 2, the toner is transferred to an electrostatic latent image on the photoreceptor 2 to form a toner image.

  Further, the toner remaining on the developing roller 41 without being transferred onto the photosensitive member 2 is collected by the supply roller 42 when it is conveyed again to the nip portion where the supply roller 42 and the developing roller 41 are in contact with each other. In the present embodiment, the supply roller 42 rotates in the supply nip so as to move in the direction opposite to the surface movement direction of the developing roller 41 (in the counter direction). Thus, the residual toner on the developing roller 41 is collected by being scraped off by the supply roller 42 rotating in the counter direction.

3 is a cross-sectional view taken along the line BB in FIG.
As shown in FIG. 3, the supply roller 42 includes a core material 42 a serving as a rotation shaft, and an elastic layer 42 c disposed on the outer periphery of the core material 42 a via an adhesive layer 42 b. The core material 42a is formed of a metal material or the like, and the elastic layer 42c is formed of a foamed elastic member such as foamed polyurethane, foamed silicone, or foamed EPDM (ethylene-propylene-diene rubber). The adhesive layer 42b is an adhesive such as hot melt made of a thermoplastic resin, a double-sided adhesive tape, or the like. The supply roller 42 is rotatably supported by holding both end portions of the core member 42 a in the developing container 40.

  Further, as shown in FIG. 3, the developing container 40 is provided with an end seal 50 that contacts the peripheral surface of the developing roller 41 on the end side. The end seal 50 is attached to a seal attachment portion 40 b provided so as to protrude from the side wall inner surface 40 a of the developing container 40 in the axial direction of the supply roller 42. The end seal 50 seals between the developing roller 41 and the developing container 40, thereby suppressing toner leakage from the end of the developing roller 41. Note that the end seal 50 is also provided on the end side opposite to the end of the developing roller 41 shown in FIG.

Hereinafter, the structure of the characteristic part of this invention is demonstrated.
As shown in FIG. 3, in the present invention, the end of the supply roller 42, specifically, the axial end of the elastic layer 42c is in contact with the end seal 50 and is compressed in the axial direction.

  Specifically, as shown by a two-dot chain line in FIG. 4, the elastic layer 42 c of the supply roller 42 is formed to have a length that overlaps the end seal 50 in the axial direction. In the state where 42 is assembled, the overlapping portion U of the elastic layer 42c is compressed in the axial direction. In the present embodiment, the portion Q (the lower portion in the figure) Q of the elastic layer 42c that does not contact the end seal 50 is also accompanied by the compressive deformation in the axial direction due to the contact with the end seal 50. It is slightly deformed by being pulled in the upper right direction.

  As described above, in the present invention, the end of the supply roller 42 is brought into contact with the end seal 50 without a gap, so that the toner adheres as in the conventional example shown in FIG. The end region J on the developing roller that is not in contact with the supply roller is not generated. That is, in the case of the present invention, the supply roller 42 is in contact with the entire area of the developing roller 41 where the toner adheres, so that the toner remaining on the end side of the developing roller 41 is also collected by the supply roller 42. Will be able to. As a result, it is possible to prevent the occurrence of filming on the end side of the developing roller 41 and to avoid the occurrence of background stains on the paper.

  The supply roller 42 and the end seal 50 do not necessarily have to be in close contact as long as they are in contact with each other. However, as in the present embodiment, the end of the supply roller 42 is compressed in the axial direction, and the end portion By closely contacting the seal 50, the occurrence of filming can be more reliably prevented.

  As described above, it is possible to prevent the occurrence of filming by bringing the end of the supply roller 42 into contact with the end seal 50. On the other hand, however, the supply roller 42 comes into contact with the end seal 50 to generate friction between them. In particular, as shown in FIG. 3, the end of the supply roller 42 is in contact with the axially compressed state, or the end of the supply roller 42 is also in contact with the seal mounting portion 40b of the developing container 40. If so, the load due to friction tends to increase. The friction between the two causes an increase in the rotational torque of the supply roller 42, heat generation, breakage of the roller end portion, and the like, and measures to reduce the friction are necessary.

  Therefore, in the present invention, as shown in FIG. 3, a non-adhesive region E in which the elastic layer 42c is non-adhered to the core member 42a is provided over a predetermined range from the end of the supply roller 42. Further, in this non-bonded region E, the elastic layer 42c is not bonded to the core member 42a over the entire circumferential direction.

  Thus, by providing the non-adhesion area | region E in the supply roller 42, in the non-adhesion area | region E, the deformation | transformation to the axial direction of the elastic layer 42c is no longer restrained by the core material 42a. That is, since the range in which the elastic layer 42c is allowed to deform when the supply roller 42 contacts the end seal 50 is long, stress due to compression can be dispersed in the axial direction. As a result, the contact pressure between the supply roller 42 and the end seal 50 is reduced, and the load due to friction can be reduced.

  On the other hand, in the configuration in which the non-adhesive region E is not provided on the supply roller 42 as in the comparative example shown in FIG. 10 (the configuration in which the elastic layer 42c is bonded over the entire axial direction), the end of the elastic layer 42c. Is deformed in the axial direction by the core material 42a. In this case, since the deformation | transformation range of the elastic layer 42c when the supply roller 42 contacts the edge part seal | sticker 50 is short, the stress concentration by compression generate | occur | produces. As a result, the contact pressure between the supply roller 42 and the end seal 50 increases, and the load due to friction also increases.

  Thus, unlike the comparative example described above, the present invention can reduce the load caused by friction at the location where the supply roller 42 and the end seal 50 are in contact with each other. Heat generation, breakage of the roller end portion, and the like can be suppressed.

  Further, the axial length L of the non-bonded region is a portion where the supply roller 42 is compressed by contact with the end seal 50 in a state where the end seal 50 indicated by a two-dot chain line in FIG. Is set to be longer than the axial length N.

  Specifically, the axial length L of the non-bonded region E (in a state where the elastic layer 42c is not compressed in the axial direction) is preferably 3 mm or more and 30 mm or less. This is because if the axial length L of the non-bonding region E is less than 3 mm, the pressure generated at the end of the supply roller 42 cannot be effectively dispersed, and the roller end may be damaged. It is. Further, when the axial length L of the non-adhesion region E is longer than 30 mm, a circumferential twist occurs in the non-adhesion region E due to frictional resistance with the end seal 50 when the supply roller 42 rotates, and the toner supply amount This is because unevenness may occur.

FIG. 5 shows the results of tests conducted to confirm the effects of the present invention.
In this test, the axial length of the non-bonded region, the amount of biting of the end seal (the axial length of the portion where the supply roller is compressed), and the repulsive force of the supply roller are set separately. About Examples 1-4, the presence or absence of the edge part breakage of a supply roller and edge part soiling was investigated.

Hereinafter, this test will be described in detail.
In each of Examples 1 to 6, a color printer (Ricoh IPSiO SP C310) was used so that the process unit and toner cartridge shown in FIG. 2 could be inserted. The process unit is driven by an image forming drive motor, and the toner cartridge is driven by enabling the process cartridge drive source to be connected to the toner cartridge by a clutch. The toner cartridge can be replenished by connecting the drive gear of the toner cartridge. As the toner, black toner having an average particle diameter of 6.3 μm was used.

  The supply roller in each Example 1-6 used what was formed in the length which an elastic layer overlaps with an end part seal in an axial direction as shown in FIG. Detailed conditions of the supply roller are as shown in FIG. As for the repulsive force of the supply roller, the entire elastic layer of the supply roller was applied to the SUS flat plate, and the repulsive force when pushed in by 1.1 mm was measured with a push-pull gauge. Further, in order to secure a pushing amount of 1.1 mm, rollers having an outer diameter 2.2 mm smaller than the outer diameter of the supply roller were attached to both ends of the supply roller, and the supply roller was applied to the flat plate.

  Then, in an environment of a temperature of 10 ° C. and a humidity of 15%, printing of an image with a printing rate of 2% was performed three times for each job until the traveling distance of the photosensitive member (surface moving distance) reached 5000 m. . Thereafter, the supply roller and the photosensitive member were observed, and it was confirmed whether the end portion of the supply roller was damaged and the end portion was soiled.

  As a result, as shown in FIG. 5, in any of Examples 1 to 6, the supply roller end portion breakage and end portion soiling did not occur. In each of the examples, the edge soiling did not occur. As described above, the supply roller is brought into contact with the edge seal, so that the filming at the edge of the developing roller can be prevented. It is thought to be because. Further, the end portion of the supply roller was not damaged because the non-adhesive region (in the example, the axial length was in the range of 5.3 to 6.7 mm) was provided, and the stress due to the compression of the supply roller This is probably because the load due to friction could be reduced. Further, the smaller the repulsive force of the supply roller, the pressure applied to the end of the supply roller can be reduced. Therefore, the repulsive force when the elastic layer of the supply roller is compressed by 1.1 mm may be 25 N or less. preferable.

FIG. 6 is a cross-sectional view of a developing device according to another embodiment of the present invention.
In the embodiment shown in FIG. 6, a low friction member 60 is interposed between the end of the supply roller 42 (elastic layer 42 c) and the end seal 50. Other than that, it is the same structure as the said embodiment.

  Thus, by interposing the low friction member 60 between the end portion of the supply roller 42 and the end seal 50, it is possible to further reduce the friction load generated at the end portion of the supply roller 42. As the low friction member 60, for example, a member having a small surface frictional resistance, such as a member having a surface treated with fluorine, a nylon member, or a sponge having a surface skin layer is desirable. Furthermore, the friction coefficient of the low friction member 60 is desirably 0.5 or less under no lubrication. The thickness of the low friction member 60 (axial thickness) is preferably 0.5 mm or less so as not to increase the amount of compression of the supply roller 42.

  As shown in FIG. 7, the low friction member 60 in the present embodiment is formed in a ring shape disposed over the entire circumferential direction of the elastic layer 42 c of the supply roller 42. A hole 60 a is formed in the center of the low friction member 60, and the core member 42 a of the supply roller 42 is inserted into the hole 60 a, so that the low friction member 60 is rotatably held with respect to the supply roller 42. Has been. As described above, the ring-shaped low friction member 60 is arranged over the entire circumferential direction of the elastic layer 42c, so that the amount of axial compression caused by the supply roller 42 contacting the end seal 50 is reduced. It can be made uniform over the entire circumferential direction. Thereby, it is possible to further reduce the frictional load generated at the end of the supply roller 42.

FIG. 8 is a view of the supply roller 42 provided with the low friction member 60 viewed from the axial direction.
In FIG. 8, the dotted line G indicates the radial direction with respect to the outer periphery of the elastic layer of the elastic layer 42 c of the supply roller 42 when the supply roller 42 and the developing roller 41 are assembled in the developing device and in contact with each other. It shows the position to bite in. The low friction member 60 is disposed closer to the inner diameter side than the biting position of the developing roller 41 indicated by a dotted line G so as not to contact the surface of the developing roller 41. As described above, the low friction member 60 is disposed at a position where it does not contact the developing roller 41 so that the low friction member 60 does not hinder the contact between the developing roller 41 and the supply roller 42.

  As described above, according to the present invention, the occurrence of filming on the end side of the developing roller 41 can be prevented, but in order to prevent the occurrence of filming to a higher degree, the embodiment shown in FIG. As described above, end exposure means 70 for exposing both ends of the photoreceptor 2 may be provided. The edge exposure means 70 may be an exposure means that is separate from the exposure apparatus 7 (see FIG. 1) that is driven by a normal image forming operation, or may be the same or integrated. Good.

  In a normal image forming operation, an image is formed on the photosensitive member 2 within a range indicated by a symbol X in FIG. However, in the present invention, since the supply roller 42 is longer in the axial direction than before and is in contact with the end seal 50, the region V closer to the axial end than the region X where the image is formed. In this case, the toner is supplied from the supply roller 42 onto the developing roller 41. Basically, the toner supplied to the developing roller 41 in this region V is collected again by the supply roller 42, so that filming on the developing roller 41 is rare. However, since the toner collecting function may be deteriorated due to deterioration of the supply roller 42 over time, the end portion (region V) on the photosensitive member 2 is exposed by the end portion exposure unit 70, and the developing roller 41 is exposed. The remaining toner may be forcibly transferred to the photoreceptor 2. The toner transferred from the developing roller 41 to the photoconductor 2 is removed by a cleaning device 5 (see FIG. 1) provided around the photoconductor 2. As described above, the end exposure unit 70 functions as a developer carrying member cleaning unit that transfers the toner carried on the end side (region V) of the developing roller 41 to the photosensitive member 2 and removes the toner. As a result, the occurrence of filming on the end side of the developing roller 41 can be prevented to a higher degree. The timing for driving the edge exposure unit 70 may be set as appropriate according to the cumulative driving time of the image forming apparatus, regardless of the normal image forming operation.

  As described above, according to the present invention, filming on the end side of the developer carrying member (developing roller) is achieved by bringing the end of the developer supplying member (supplying roller) into contact with the end seal. Occurrence can be prevented. As a result, it is possible to avoid the occurrence of background contamination on the edge side of the sheet, and to improve the quality.

  Further, according to the present invention, the developer supply member is in contact with the end seal by providing a non-adhesive region over a predetermined range from the end of the developer supply member that contacts the end seal of the elastic layer. It becomes possible to disperse the stress generated by doing in the axial direction of the elastic layer. As a result, it is possible to reduce the load due to friction, and thus it is possible to suppress an increase in rotational torque, heat generation, breakage of the end portion, and the like of the developer supply member.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. The image forming apparatus to which the present invention can be applied is not limited to the printer shown in FIG. 1, but may be a copier, a facsimile, or a complex machine thereof.

1Y, 1M, 1C, 1Bk Process unit 2 Photoconductor (latent image carrier)
4 Developing Device 41 Developing Roller (Developer Carrier)
42 Supply roller (developer supply member)
42a Core material 42b Adhesive layer 42c Elastic layer 50 End seal 60 Low friction member 70 End exposure means (developer carrier cleaning means)
100 Image forming apparatus body E Non-adhesion area L Length of non-adhesion area in the axial direction

JP 2000-75654 A

Claims (10)

A developer carrying member carrying a developer on the surface;
A developer supply member that contacts the surface of the developer carrier and supplies the developer onto the developer carrier;
An end seal contacting the end side of the developer carrier,
In the developing device, the developer supply member includes a core material and an elastic layer bonded to the outer periphery of the core material.
An end of the elastic layer of the developer supply member is brought into contact with the end seal;
A developing device comprising: a non-adhesive region that is non-adhering to the core member over a predetermined range from an end portion of the elastic layer that contacts the end seal.   The developing device according to claim 1, wherein an axial length of the non-adhesion region is 3 mm or more and 30 mm or less.   The developing device according to claim 1, wherein a low friction member is interposed between an end of the elastic layer and the end seal.   The developing device according to claim 3, wherein a friction coefficient of the low friction member is 0.5 or less.   The developing device according to claim 3, wherein the low friction member is disposed over the entire circumferential direction of the elastic layer.   6. The developing device according to claim 3, wherein the low friction member is disposed on an inner diameter side of a position where the developer carrying member bites into an outer periphery of the elastic layer.   The developing device according to claim 1, wherein a repulsive force when the elastic layer is compressed by 1.1 mm is 25 N or less. A latent image carrier that carries a latent image on the surface;
A developing device for supplying a developer to the latent image on the latent image carrier,
In the process unit configured to be detachable from the image forming apparatus main body,
A process unit comprising the developing device according to claim 1 as the developing device.   An image forming apparatus comprising the developing device according to claim 1 or the process unit according to claim 8.   The image forming apparatus according to claim 9, further comprising a developer carrier cleaning unit that transfers the developer carried on the end side of the developer carrier to the latent image carrier regardless of an image forming operation. apparatus.

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