Development device and image formation apparatus

Abstract

To appropriately ensure adhesion between a layer thickness regulating member and a sealing member.SOLUTION: A development device includes: a toner carrier 21; a layer thickness regulating member 24 that regulates the layer thickness of toner on the toner carrier surface by means of a regulating portion 24b pressed against the surface of the toner carrier; and a sealing member 26 that is disposed between an end surface 21a of the toner carrier and a seal holding surface 29a facing the end surface. The layer thickness regulating member has a protrusion 24a on the rear surface of the regulating portion. The sealing member is arranged so as to sandwich a protrusion portion existing at a position opposed to the end surface of the toner carrier in the protrusion of the layer thickness regulating member between itself and the end surface. The seal holding surface includes protruding portions 29a1, 29a2 at positions opposed to at least one of an upstream adjacent portion and a downstream adjacent portion in a toner carrier surface movement direction of the protrusion portion.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a developing device and an image forming apparatus.

Background Art

[0002] Conventionally, there is known a device having a toner carrier, a layer thickness regulating member that regulates the layer thickness of toner on the surface of the toner carrier by a regulating portion pressed against the surface of the toner carrier, and a seal member disposed between the end surface of the toner carrier and a seal holding surface facing the end surface.

[0003] For example, Patent Document 1 discloses a developing device that thins a toner layer on a developing roller by pressing the tip of a developing blade (layer thickness regulating member) against the surface of the developing roller (toner carrier) near the cutting edge portion (regulating portion). In this developing device, in order to ensure the flatness near the cutting edge portion, a bent portion (convex portion) is formed at the cutting edge portion of the developing blade. This developing device is provided with a seal member for preventing toner leakage from the axial end of the developing roller so as to be in close contact with the axial end region (end surface) of the circumferential surface of the developing roller. Further, a developing blade is interposed between this seal member and the axial end region of the circumferential surface of the developing roller. Therefore, the portion of the seal member that contacts the bent portion (convex portion) at the axial end of the developing blade is crushed and deformed by the bent portion, thereby ensuring the adhesion between the developing blade and the seal member near the bent portion.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional developing device, when the layer thickness regulating member has a convex portion such as the bent portion, it has been difficult to appropriately ensure the adhesion between the layer thickness regulating member and the seal member near the convex portion.

Means for Solving the Problems

[0005] In order to solve the above problems, the present invention includes a toner carrier, a layer thickness regulating member that regulates the layer thickness of toner on the surface of the toner carrier by a regulating portion pressed against the surface of the toner carrier, and a seal member disposed between an end surface of the toner carrier and a seal holding surface facing the end surface. The layer thickness regulating member has a convex portion on the back surface of the regulating portion, and the seal member is disposed so as to sandwich a convex portion portion existing at a position facing the end surface of the toner carrier among the convex portions of the layer thickness regulating member between the seal member and the end surface. In the developing device, the seal holding surface has a protrusion at a position facing at least one of an upstream adjacent portion and a downstream adjacent portion of the toner carrier surface movement direction of the convex portion portion (hereinafter, also appropriately referred to as a "convex portion adjacent portion").

Advantages of the Invention

[0006] According to the present invention, it is possible to appropriately ensure the adhesion between the layer thickness regulating member and the seal member in the vicinity of the convex portion portion while suppressing the problem caused by the excessive contact pressure between the layer thickness regulating member of the convex portion portion and the surface of the toner carrier.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0008] 〔Embodiment 1〕 Hereinafter, an embodiment of an image forming apparatus including a developing device according to the present invention (hereinafter, this embodiment is referred to as "Embodiment 1") will be described. First, the basic configuration of a printer as an image forming apparatus according to Embodiment 1 will be described. FIG. 1 is a schematic schematic diagram showing the printer according to Embodiment 1. In the figure, this printer includes a photoreceptor 1 as a latent image carrier, a paper feed cassette 100 configured to be detachable from the main body housing 50, and the like. The paper feed cassette 100 stores a plurality of recording sheets S in a sheet bundle state as a recording material.

[0009] The recording sheet S in the paper feed cassette 100 is sent out from the paper feed cassette 100 by the rotational drive of the main body paper feed roller 41, and only the topmost sheet is separated and sent out at the separation nip between the main body paper feed roller 41 and the separation pad 48, and reaches the main body paper feed path R1, which is the first conveying path. Thereafter, the recording sheet S is sandwiched (held) in the conveying nip of the relay roller pair 42, which is the upper conveying roller pair, and is conveyed in the main body paper feed path R1 from the upstream side to the downstream side in the conveying direction.

[0010] The downstream end of the main body paper feed path R1 communicates with a common transport path R3, on which a pair of registration rollers 43 are disposed. A registration sensor 49 for detecting the recording sheet S is disposed on the common transport path R3, upstream of the pair of registration rollers 43 in the transport direction. The transport of the recording sheet S is temporarily stopped with its leading edge abutting against the nip of the stopped pair of registration rollers 43. At the time of abutment, the skew of the recording sheet S is corrected. The registration sensor 49 is also used for initial operation and for checking the remaining sheets when the device is stopped due to an abnormality.

[0011] The pair of registration rollers 43 start rotating at a timing when the recording sheet S can be superimposed on the toner image on the surface of the photoconductor 1 at the transfer nip, and feed the recording sheet S toward the transfer nip. At this time, the pair of relay rollers 42 simultaneously start rotating and resume the transport of the recording sheet S that was temporarily stopped.

[0012] The main body casing 50 of this printer is provided with a manual feed unit 30 including a manual feed tray 31, a manual feed roller 32, a separation pad 33, a manual feed bottom plate 34, a manual feed bottom plate cam 35, and the like. The recording sheet S manually inserted into the manual feed tray 31 of the manual feed unit 30 is sent out from the manual feed tray 31 to the manual feed path R2, which is the second conveyance path, by the rotational drive of the manual feed roller 32. The downstream end of the manual feed path R2 merges with the downstream end of the main body feed path R1 into a common conveyance path R3. The recording sheet S sent out by the manual feed roller 32 passes through a separation nip formed by the contact between the manual feed roller 32 and the separation pad 33 in the manual feed path R2, and then is sent into the common conveyance path R3 and conveyed to the registration roller pair 43. Thereafter, this recording sheet S, like the recording sheet S sent out from the paper feed cassette 100, is sent to the transfer nip after passing through the registration roller pair 43.

[0013] FIG. 2 is an enlarged schematic view showing an enlarged view of the photosensitive member 1 and its surrounding configuration in this printer. Around the drum-shaped photosensitive member 1 that is rotationally driven in the clockwise direction in the figure, a cleaning blade 2, a recovery screw 3, a charging roller 4, a charging cleaning roller 5, a scraper 6, a latent image writing device 7, a developing device 20, a transfer roller 10, and the like are arranged. The charging roller 4 having a conductive rubber roller portion rotates while contacting the photosensitive member 1 to form a charging nip. A voltage is applied to this charging roller 4 from a charging power source. Thereby, the surface of the photosensitive member 1 is uniformly charged by the charging bias generated between the surface of the photosensitive member 1 and the surface of the charging roller 4 at the charging nip.

[0014] The latent image writing device 7 includes an LED array and performs optical writing on the uniformly charged surface of the photosensitive member 1 with LED light. Among the uniformly charged surface portions of the photosensitive member 1, the potential of the region irradiated with the writing light decays, and an electrostatic latent image is formed on the surface of the photosensitive member 1.

[0015] The electrostatic latent image passes through the development region facing the developing device 20 as the photoreceptor 1 rotates. The developing device 20 has a circulation conveyance section and a developing section within the developing case 29. The circulation conveyance section houses toner, which is a one-component developer. The circulation conveyance section includes toner conveyance members 23A and 23B for conveying the toner, a toner supply roller 22 for supplying the toner to the developing roller 21, and the like.

[0016] The developing roller 21 as a toner carrier is supplied with toner at the contact location with the toner supply roller 22. The toner supplied to the developing roller 21 is conveyed as the developing roller 21 rotates, and when passing through the opposing region with the toner layer regulating blade 24 as a layer thickness regulating member that is pressed against and disposed on the surface of the developing roller 21, its layer thickness is regulated. Thereafter, in the development region facing the photoreceptor 1, it is conveyed while rubbing against the surface of the photoreceptor 1.

[0017] A development bias having the same polarity as the uniform charging potential (background potential) of the toner and the photoreceptor 1 is applied to the developing roller 21. The absolute value of this development bias is larger than the absolute value of the latent image potential and smaller than the absolute value of the background potential. For this reason, in the development region, a development potential that moves the toner from the developing roller 21 side to the photoreceptor 1 side acts between the electrostatic latent image of the photoreceptor 1 and the developing roller 21. On the other hand, a background potential that electrostatically moves the toner from the photoreceptor 1 side to the developing roller 21 side acts between the background portion of the photoreceptor 1 and the developing roller 21. Thereby, in the development region, the toner selectively adheres to the electrostatic latent image of the photoreceptor 1 and the electrostatic latent image is developed.

[0018] Above the developing device 20, a toner cartridge 9 is disposed. This toner cartridge 9 agitates the toner housed inside by an agitator 9b fixed to the rotary shaft member 9a. Then, the toner supply member 9c is rotationally driven in response to the supply operation signal output from the control unit 80, thereby supplying an amount of toner corresponding to the rotational drive amount into the developing case 29 of the developing device 20.

[0019] The toner image (image) formed on the photoreceptor 1 by development enters the transfer nip where the photoreceptor 1 and the transfer roller 10 come into contact as the photoreceptor 1 rotates. A voltage of the opposite polarity to the latent image potential of the photoreceptor 1 is applied to the transfer roller 10, whereby a transfer bias is formed in the transfer nip.

[0020] As described above, the resist roller pair 43 feeds the recording sheet S toward the transfer nip at a timing such that the recording sheet S can be superimposed on the toner image on the photoreceptor 1 within the transfer nip. The toner image on the photoreceptor 1 is transferred to the recording sheet closely attached to the toner image at the transfer nip due to the action of the transfer bias and nip pressure.

[0021] Transfer residual toner that has not been transferred to the recording sheet S adheres to the surface of the photoreceptor 1 after passing through the transfer nip. The transfer residual toner is scraped off the surface of the photoreceptor 1 by the cleaning blade 2 in contact with the photoreceptor 1, and then conveyed by the recovery screw 3 and sent to the waste toner bottle.

[0022] The surface of the photoreceptor 1 cleaned by the cleaning blade 2 is discharged by the discharging means and then uniformly charged again by the charging roller 4. Foreign substances such as toner additives and toner that could not be completely removed by the cleaning blade 2 adhere to the charging roller 4 in contact with the surface of the photoreceptor 1. This foreign substance transfers to the charging cleaning roller 5 in contact with the charging roller 4 and is then scraped off the surface of the charging cleaning roller 5 by the scraper 6 in contact with the charging cleaning roller 5. The scraped foreign substance falls onto the above-described recovery screw 3.

[0023] In FIG. 1, the recording sheet S that has passed through the transfer nip where the photoreceptor 1 and the transfer roller 10 are in contact is sent to the fixing device 44. The fixing device 44 forms a fixing nip by the contact between a fixing roller 44a that incorporates a heat source such as a halogen lamp and a pressure roller 44b that is pressed against it. A toner image is fixed on the surface of the recording sheet S sandwiched between the fixing nips by the action of heating and pressing. After that, the recording sheet S that has passed through the fixing device 44 is sandwiched between the discharge nips of the discharge roller pair 46 after passing through the discharge path R4.

[0024] This printer can be switched between a single-sided mode of forming an image only on one side of the recording sheet S and a double-sided mode of forming images on both sides of the recording sheet S and executed. In the case of the single-sided mode or in the double-sided mode where images have already been formed on both sides of the recording sheet, the discharge roller pair 46 continues to be driven forward to discharge the recording sheet S in the discharge path R4 outside the machine. The discharged recording sheet S is stacked on the stack portion provided on the upper surface of the main body housing 50.

[0025] On the other hand, in the double-sided mode and when an image is formed only on one side of the recording sheet S, at the timing when the rear end portion of the recording sheet S enters the discharge nip of the discharge roller pair 46, the discharge roller pair 46 is driven in reverse. At this time, the switching claw 47 disposed near the downstream end of the discharge path R4 operates to block the discharge path R4 and open the inlet of the reverse re-feed path R5. The recording sheet S that has started to reverse by the reverse drive of the discharge roller pair 46 is fed into the reverse re-feed path R5. The downstream end of the reverse re-feed path R5 merges with the upstream side of the registration roller pair 43 in the common conveyance path R3, and after being conveyed in the reverse re-feed path R5, it is re-fed to the registration roller pair 43 in the common conveyance path R3. After that, after the toner image is transferred to the other side at the transfer nip, it is discharged outside the machine through the fixing device 44, the discharge path R4, and the discharge roller pair 46.

[0026] The fixing device 44 of the first embodiment includes a cleaning roller 44d for removing deposits such as toner and paper dust adhering to the surface of the pressure roller 44b. This cleaning roller 44d comes into contact with and separates from the pressure roller 44b by a contact-and-separation mechanism.

[0027] Also, the fixing device 44 includes members that constitute the portion from the fixing nip in the paper discharge path R4 to the switching claw 47. Specifically, the fixing device 44 includes a paper discharge guide member 59, a paper discharge reversing guide member 58, and a relay conveyance roller pair 51. The paper discharge guide member 59 faces the contact surface of the recording sheet S that has passed through the fixing nip with the fixing roller 44a and has a guide portion 59a for guiding the recording sheet S to the switching claw 47. The paper discharge reversing guide member 58 includes a paper discharge guide portion 58b and a reversing guide portion 58a. The paper discharge guide portion 58b faces the contact surface of the recording sheet S that has passed through the fixing nip with the pressure roller 44b and guides the recording sheet S to the switching claw 47. The reversing guide portion 58a faces and guides the image formation surface of the recording sheet on the reversing re-feed path R5 that has passed through the switching claw 47. Also, the paper discharge reversing guide member 58 is attached with a driven roller 52b of the reversing conveyance roller pair 52 for conveying the recording sheet in the reversing re-feed path R5.

[0028] Also, an opening / closing cover 55 is provided on the left side surface in FIG. 1 of the main body housing 50 of this printer. This opening / closing cover 55 is provided with a reversing guide member 57 that faces and guides the non-image formation surface of the recording sheet on the reversing re-feed path R5, and a driving roller 52a of the reversing conveyance roller pair 52 is attached to the reversing guide member 57.

[0029] FIG. 3 is a front view showing the configuration near the axial end of the developing roller 21, that is, near the end in the width direction of the developing roller (hereinafter, also simply referred to as the "width direction") in the developing case 29 of the developing device 20 of the first embodiment. FIG. 4 is a perspective view showing the configuration near the axial end of the developing roller 21 in a state where the developing roller 21 is removed from the developing case 29 of the developing device 20 of the first embodiment. FIG. 5 is a side view of the toner layer regulating blade 24 of the first embodiment as viewed from the axial direction (developing roller width direction) of the developing roller. FIG. 6 is a perspective view of the seal member 26 of the first embodiment as viewed from the side facing the end surface 21a of the developing roller 21.

[0030] The toner layer regulating blade 24 is, for example, a plate-like member made of a stainless alloy plate, and the root portion of the toner layer regulating blade 24 is supported by the blade support portion 25 of the developing case 29. As shown in FIG. 5, the toner layer regulating blade 24 of the first embodiment is formed with a bent portion 24a (convex portion) whose tip portion is bent in a direction away from the surface of the developing roller 21.

[0031] The toner layer regulating blade 24 is arranged to press the vicinity (regulating portion) 24b of the root portion of the bent portion 24a against the surface (circumferential surface) of the developing roller 21 by utilizing the elasticity of the toner layer regulating blade 24 itself. The layer thickness of the toner on the surface of the developing roller 21 is regulated at the vicinity (regulating portion) 24b of the root portion of the bent portion 24a of the toner layer regulating blade 24.

[0032] As shown in FIGS. 3 and 4, in the developing device 20, a seal member 26 is disposed between the end surface 21a of the developing roller 21 and the seal holding surface 29a of the developing case 29 facing the end surface 21a in order to prevent toner leakage from the axial end of the toner in the developing case 29 to the outside of the developing roller 21.

[0033] As shown in FIG. 6, the seal member 26 has a structure in which a surface layer portion 26a that contacts the end surface 21a of the developing roller 21, an elastic portion 26b, and a double-sided tape 26c that is an adhesive layer are laminated. The surface layer portion 26a can be formed of a member made of fibers such as a pile shape, a felt shape, a brush shape, or a material having a low coefficient of friction such as a polymer polyethylene. The elastic portion 26b can be formed of an elastic member such as a sponge or a foamed urethane. The double-sided tape 26c is for adhering the seal member 26 to the seal holding surface 29a of the developing case 29.

[0034] Before the development roller 21 is assembled, the seal member 26 is held on the seal holding surface 29a by the double-sided tape 26c, and then, when the development roller 21 is assembled, it is compressed so as to be crushed by the end surface 21a of the development roller 21. As a result, the end surface 21a of the development roller 21 and the seal member 26 are in close contact with each other, suppressing toner leakage.

[0035] Here, as shown in FIGS. 3 and 4, in the width direction of the development roller, the width-direction end portions of the toner layer regulating blade 24 extend to the end surface 21a of the development roller 21 facing the seal member 26. Therefore, the seal member 26 is arranged so as to sandwich the extended portion (the end portion of the bent portion 24a existing at a position facing the end surface 21a of the development roller 21, which is a convex portion) of the bent portion 24a of the toner layer regulating blade 24 between the end surface 21a of the development roller 21. Therefore, the seal member 26 is crushed and deformed by the bent portion 24a of the toner layer regulating blade 24.

[0036] FIG. 7 is an enlarged cross-sectional view when the axial end portion (width-direction end portion of the development roller 21) of the development roller 21 and the toner layer regulating blade 24, etc. in a conventional developing device are cut by a cross-section orthogonal to the axis of the development roller 21. If the contact pressure between the end surface 21a of the development roller 21 and the seal member 26 is insufficient, the deformation of the seal member 26 cannot sufficiently follow the shape of the bent portion 24a of the toner layer regulating blade 24. Therefore, conventionally, as shown in FIG. 7, gaps E1 and E2 are formed between the seal member 26 and the adjacent portions on the downstream side or the upstream side in the rotation direction (surface movement direction) of the development roller of the bent portion 24a of the toner layer regulating blade 24. Therefore, there is a possibility that toner leakage may occur from the gaps E1 and E2 between the toner layer regulating blade 24 and the seal member 26.

[0037] On the other hand, in order to reduce or eliminate these gaps E1 and E2, if an attempt is made to deform the seal member 26 so that it can sufficiently follow the shape of the bent portion 24a of the toner layer regulating blade 24, the seal member 26 will contact the bent portion 24a of the toner layer regulating blade 24 with a strong contact pressure. Therefore, the root portion (regulation portion 24b) of the bent portion 24a of the toner layer regulating blade 24 will contact the end surface 21a of the developing roller 21 with an excessive contact pressure. As a result, various problems will occur, such as an increase in the rotational driving torque of the developing roller 21, a temperature rise due to frictional heat generated at the contact portion between the toner layer regulating blade 24 and the end surface 21a of the developing roller 21, and wear of the developing roller 21 due to rubbing at the contact portion.

[0038] FIG. 8 is an enlarged cross-sectional view of the axial end portion of the developing roller 21 and the toner layer regulating blade 24, etc. in the developing device 20 of the first embodiment, when cut along a cross-section orthogonal to the axis of the developing roller 21. FIG. 9 is a partial perspective view showing the vicinity of the seal holding surface 29a of the developing case 29 in the developing device 20 of the first embodiment. FIG. 10 is a partial front view showing the vicinity of the seal holding surface 29a of the developing case 29 in the developing device 20 of the first embodiment. FIG. 11 is a partial front view showing the vicinity of the seal holding surface 29a of the developing case 29 and the toner layer regulating blade 24 in the developing device 20 of the first embodiment.

[0039] In the first embodiment, on the seal holding surface 29a that holds the seal member 26 at a position facing the end surface 21a of the developing roller 21, protrusions 29a1 and 29a2 are provided at positions corresponding to the upstream adjacent portion and the downstream adjacent portion (hereinafter referred to as "bent portion adjacent portions") of the bent portion 24a of the toner layer regulating blade 24 in the rotational direction of the developing roller. According to this, the portion of the seal member 26 facing the bent portion adjacent portions of the toner layer regulating blade 24 can be pushed toward the bent portion adjacent portions side by the protrusions 29a1 and 29a2 on the seal holding surface 29a.

[0040] As a result, even if the contact pressure between the root portion (restriction portion 24b) of the bent portion 24a of the toner layer regulating blade 24 and the end surface 21a of the developing roller 21 is configured to be within an appropriate range (within the range where the above-mentioned problem is suppressed), as shown in FIG. 8, the gaps E1 and E2 between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26 can be made smaller than those in the conventional apparatus of FIG. 7 or eliminated. Therefore, according to the first embodiment, while suppressing the above-mentioned problems, the adhesion between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26 is ensured, and toner leakage can be suppressed.

[0041] Further, if the double-sided tape 26c is provided over the entire area on the seal holding surface 29a side of the seal member 26, the adhesion between the seal member 26 and the seal holding surface 29a becomes strong. However, an adhesive layer such as the double-sided tape 26c is generally less stretchable and less bendable than the elastic portion 26b of the seal member 26. Therefore, it is difficult for the double-sided tape 26c to deform so as to follow the shapes of the protrusions 29a1 and 29a2 on the seal holding surface 29a. As a result, there is a possibility that it is difficult to push out the portion of the seal member 26 facing the portion adjacent to the bent portion of the toner layer regulating blade 24 toward the side of the portion adjacent to the bent portion by the protrusions 29a1 and 29a2 on the seal holding surface 29a.

[0042] In such a case, it is preferable to provide the double-sided tape 26c avoiding the regions facing the protrusions 29a1 and 29a2 on the seal holding surface 29a and the vicinity thereof. Thereby, when pushing out the portion of the seal member 26 facing the portion adjacent to the bent portion of the toner layer regulating blade 24 toward the side of the portion adjacent to the bent portion by the protrusions 29a1 and 29a2, the double-sided tape 26c does not get in the way, and it is easy to ensure the adhesion between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26.

[0043] In Embodiment 1, as shown in FIG. 9, the position P1 at the widthwise end of the seal holding surface 29a is preferably located outside the developing roller widthwise direction with respect to the protrusions 29a1 and 29a2. According to this, the portion of the seal holding surface 29a outside the developing roller widthwise direction with respect to the protrusions 29a1 and 29a2 and the seal member 26 can be adhered with the double-sided tape 26c. Therefore, even when the double-sided tape 26c is provided while avoiding the region facing the protrusions 29a1 and 29a2 on the seal holding surface 29a and its vicinity region, the seal holding surface 29a and the seal member 26 can be adhered with the double-sided tape 26c over the entire region in the developing roller rotation direction. Thus, the adhesiveness between the seal holding surface 29a and the seal member 26 can be maintained.

[0044] Also, as shown in FIG. 11, the end position P2 of the protrusions 29a1 and 29a2 outside the developing roller widthwise direction is preferably located inside the developing roller widthwise direction with respect to the end position P3 of the bent portion 24a of the toner layer regulating blade 24. In this case, in the developing roller widthwise direction, there are no protrusions 29a1 and 29a2 between the end position P2 of the protrusions 29a1 and 29a2 and the end position P3 of the bent portion 24a, and gaps E1 and E2 of the same size as before are formed between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26. However, on the inner side in the developing roller widthwise direction (the inner side of the developing case) rather than this, since the adhesion between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26 is ensured by the protrusions 29a1 and 29a2, toner leakage is suppressed.

[0045] On the other hand, according to this configuration, a wider portion of the seal holding surface 29a outside the developing roller widthwise direction with respect to the protrusions 29a1 and 29a2 can be secured. Therefore, even when the double-sided tape 26c is provided while avoiding the region facing the protrusions 29a1 and 29a2 on the seal holding surface 29a and its vicinity region, the seal holding surface 29a and the seal member 26 can be adhered with the double-sided tape 26c with a wider adhesion area. Thus, the adhesiveness between the seal holding surface 29a and the seal member 26 can be maintained.

[0046] In addition, in the first embodiment, the protrusions 29a1 and 29a2 are provided at the positions facing both the upstream adjacent position and the downstream adjacent position in the rotation direction of the developing roller of the bent portion 24a of the toner layer regulating blade 24. However, the protrusions may be provided at only one of the positions.

[0047] 〔Second Embodiment〕 Next, another embodiment of the image forming apparatus including the developing device according to the present invention (hereinafter, this embodiment is referred to as "Embodiment 2") will be described. In the following description, the description of the points common to the above-described first embodiment will be omitted.

[0048] FIG. 12 is an enlarged cross-sectional view when the axial end portion of the developing roller 21 and the toner layer regulating blade 24 and the like in the developing device 20 of the second embodiment are cut along a cross-section orthogonal to the axis of the developing roller 21. FIG. 13 is a partial perspective view showing the vicinity of the seal holding surface 29a of the developing case 29 in the developing device 20 of the second embodiment.

[0049] In the second embodiment, a recess 29a3 is provided at a position on the seal holding surface 29a that holds the seal member 26 at a position facing the end surface 21a of the developing roller 21, at a position facing the bent portion 24a of the toner layer regulating blade 24. According to this, when the seal member 26 is pushed in (crushed) by the bent portion 24a of the toner layer regulating blade 24, the portion of the seal member 26 on the side opposite to the bent portion 24a can escape into the recess 29a3 of the seal holding surface 29a. As a result, even when the seal member 26 is pushed in (crushed) by the bent portion 24a of the toner layer regulating blade 24, the amount of compression of the seal member 26 can be kept small. Therefore, the contact pressure at which the root portion (regulating portion 24b) of the bent portion 24a of the toner layer regulating blade 24 abuts against the end surface 21a of the developing roller 21 can be reduced.

[0050] Therefore, in the second embodiment, as shown in FIG. 12, in order to reduce or eliminate the gaps E1 and E2 between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26, even if the seal member 26 is configured to abut against the bent portion 24a of the toner layer regulating blade 24 with a strong contact pressure, the contact pressure between the root portion (regulating portion 24b) of the bent portion 24a of the toner layer regulating blade 24 and the end surface 21a of the developing roller 21 can be kept within an appropriate range (a range in which the above-mentioned problem is suppressed). Therefore, according to the second embodiment, while suppressing the above-mentioned problems, the adhesion between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26 can be ensured, and toner leakage can be suppressed.

[0051] In addition to the configuration including the recess 29a3 of the second embodiment, a configuration including the protrusions 29a1 and 29a2 in the first embodiment described above may be combined. In this case, by appropriately adjusting the shape and dimensions of the recess 29a3 and the shape and dimensions of the protrusions 29a1 and 29a2, it is easy to realize a configuration that can ensure the adhesion between the portion adjacent to the bent portion of the toner layer regulating blade 24 and the seal member 26 while suppressing the above-mentioned problems.

[0052] In the first and second embodiments, an example is shown in which the convex portion formed on the back surface of the regulating portion 24b (the portion that regulates the layer thickness of the toner on the surface of the developing roller 21) of the toner layer regulating blade 24 is constituted by the bent portion 24a obtained by bending the tip of the plate-like member. However, as long as the configuration has a convex portion on the back surface of the regulating portion 24b of the toner layer regulating blade 24, it is not limited to this example. For example, a configuration in which a step is provided on the back surface of the regulating portion 24b of the toner layer regulating blade 24 (a configuration in which the plate thickness of the back surface of the regulating portion 24b of the toner layer regulating blade 24 is thick) may be used.

[0053] Also, if the double-sided tape 26c is provided over the entire area on the seal holding surface 29a side of the seal member 26, the adhesion between the seal member 26 and the seal holding surface 29a becomes strong. However, there is a possibility that it becomes difficult to deform the portion of the seal member 26 facing the bent portion 24a of the toner layer regulating blade 24 toward the recess 29a3 side on the seal holding surface 29a.

[0054] In such a case, it is preferable that the double-sided tape 26c is provided avoiding the region facing the recess 29a3 on the seal holding surface 29a and the vicinity region thereof. Thereby, when the portion of the seal member 26 facing the bent portion 24a of the toner layer regulating blade 24 deforms toward the recess 29a3 side, the double-sided tape 26c does not get in the way, and the contact pressure at which the root portion (regulation portion 24b) of the bent portion 24a of the toner layer regulating blade 24 abuts against the end surface 21a of the developing roller 21 can be appropriately reduced.

[0055] In the second embodiment, as shown in FIG. 13, the position P1 at the widthwise end of the seal holding surface 29a is preferably located outside the developing roller widthwise with respect to the recess 29a3. According to this, the portion of the seal holding surface 29a outside the developing roller widthwise with respect to the recess 29a3 and the seal member 26 can be adhered with the double-sided tape 26c. Therefore, even when the double-sided tape 26c is provided avoiding the region facing the recess 29a3 on the seal holding surface 29a and the vicinity region thereof, the seal holding surface 29a and the seal member 26 can be adhered with the double-sided tape 26c over the entire region in the developing roller rotation direction. Thus, the adhesiveness between the seal holding surface 29a and the seal member 26 can be maintained.

[0056] Also, at the edge portion of the toner layer regulating blade 24 (the developing roller widthwise end of the toner layer regulating blade 24), the contact pressure with the developing roller 21 tends to be high, and an excessive contact pressure is likely to occur. Therefore, as shown in FIG. 14, the end position P4 outside the developing roller widthwise of the recess 29a3 is preferably located outside the developing roller widthwise with respect to the end position P3 of the bent portion 24a of the toner layer regulating blade 24. In this case, since the recess 29a3 exists up to the position facing the developing roller widthwise end of the bent portion 24a of the toner layer regulating blade 24, the contact pressure between the edge portion of the toner layer regulating blade 24 (the developing roller widthwise end of the toner layer regulating blade 24) and the developing roller 21 can be released by the recess 29a3, and the generation of an excessive contact pressure can be suppressed.

[0057] What has been described above is an example, and each of the following aspects has specific effects. [First Aspect] The first aspect is a developing device 20 having a toner carrier (e.g., developing roller 21), a layer thickness regulating member (e.g., toner layer regulating blade 24) that regulates the layer thickness of the toner on the surface of the toner carrier by a regulating portion 24b pressed against the surface of the toner carrier, and a seal member 26 disposed between an end surface 21a of the toner carrier and a seal holding surface 29a facing the end surface. The layer thickness regulating member has a convex portion (e.g., bent portion 24a) on the back surface of the regulating portion, and the seal member is disposed so as to sandwich a convex portion portion existing at a position facing the end surface 21a of the toner carrier among the convex portions of the layer thickness regulating member between the seal member and the end surface. In the developing device 20, the seal holding surface has protrusions 29a1 and 29a2 at a position facing at least one of adjacent portions on the upstream side and the downstream side in the toner carrier surface moving direction of the convex portion portion. The convex portion of the layer thickness regulating member existing at the position facing the end surface of the toner carrier presses against the seal member, and the seal member deforms following the shape of the convex portion, thereby ensuring the adhesion between the layer thickness regulating member near the convex portion and the seal member. However, in order to deform the seal member following the shape of the convex portion to ensure this adhesion, it is necessary to bring the seal member into contact with the convex portion of the layer thickness regulating member with a strong contact pressure. Therefore, the contact pressure between the layer thickness regulating member at the convex portion and the surface of the toner carrier becomes excessive, resulting in various problems such as an increase in the torque of the surface movement of the toner carrier, a temperature rise due to frictional heat at the contact portion, and wear of the toner carrier due to rubbing at the contact portion. On the other hand, if the contact pressure between the layer thickness regulating member at the convex portion and the surface of the toner carrier is configured to be within an appropriate range, the contact pressure between the seal member and the convex portion of the layer thickness regulating member is too small, and deformation of the seal member following the shape of the convex portion of the layer thickness regulating member cannot be achieved. As a result, a gap is formed between the portion adjacent to the convex portion of the layer thickness regulating member and the seal member, and the adhesion between the layer thickness regulating member near the convex portion and the seal member becomes insufficient. Therefore, it has been difficult to ensure the adhesion between the layer thickness regulating member near the convex portion and the seal member while suppressing the above problems. Therefore, in this aspect, on the seal holding surface that holds the seal member at a position facing the end surface of the toner carrier, a protrusion is provided at a position facing at least one of the adjacent portions (convex adjacent portions) on the upstream side and the downstream side in the toner carrier surface movement direction of the convex portion of the layer thickness regulating member. According to this, the protrusion on the seal holding surface can push out the portion of the seal member facing the at least one adjacent portion toward the convex adjacent portion side. As a result, even if the contact pressure between the layer thickness regulating member at the convex portion and the surface of the toner carrier is configured to be within an appropriate range (within the range where the above problems are suppressed), the gap between the convex adjacent portion of the layer thickness regulating member and the seal member can be reduced or eliminated. Therefore, according to this aspect, it is possible to ensure the adhesion between the layer thickness regulating member near the convex portion and the seal member while suppressing the above problems.

[0058] [Second Aspect] In the second aspect, in the first aspect, the end position P1 on the outer side in the width direction of the toner carrier of the seal holding surface is located on the outer side in the width direction of the toner carrier than the protrusion. According to this, it becomes possible to bond the seal holding surface portion on the outer side in the width direction of the toner carrier than the protrusion and the seal member. As a result, for example, even when bonding the seal holding surface and the seal member while avoiding the region facing the protrusion on the seal holding surface and the vicinity thereof, the seal holding surface and the seal member can be bonded over the entire region in the surface movement direction of the toner carrier, and the adhesiveness between the seal holding surface and the seal member can be maintained.

[0059] [Third Aspect] In the third aspect, in the first or second aspect, the end position P2 on the outer side in the width direction of the toner carrier of the protrusion is located on the inner side in the width direction of the toner carrier than the convex portion. According to this, a wider seal holding surface portion on the outer side in the width direction of the toner carrier than the protrusion can be secured. Therefore, for example, even when bonding the seal holding surface and the seal member while avoiding the region facing the protrusion on the seal holding surface and the vicinity thereof, the seal holding surface and the seal member can be bonded with a wider bonding area, and the adhesiveness between the seal holding surface and the seal member can be maintained.

[0060] [Fourth Aspect] In the fourth aspect, in any one of the first to third aspects, the seal holding surface has a concave portion 29a3 at a position facing the convex portion. According to this, when the seal member is pushed in (crushed) by the convex portion of the layer thickness regulating member, the portion of the seal member on the side opposite to the convex portion can escape into the concave portion of the seal holding surface. As a result, even if the seal member is pushed in (crushed) by the convex portion of the layer thickness regulating member, the amount of compression of the seal member can be kept small, and the contact pressure between the layer thickness regulating member of the convex portion and the surface of the toner carrier can be reduced. Therefore, even if the seal member is configured to contact the convex portion of the layer thickness regulating member with a strong contact pressure in order to reduce or eliminate the gap between the portion adjacent to the convex portion of the layer thickness regulating member and the seal member, the contact pressure between the layer thickness regulating member of the convex portion and the surface of the toner carrier can be kept within an appropriate range (within the range where the above-mentioned problem is suppressed). As a result, combined with the effect of the protrusion on the seal holding surface described above (the effect that the gap between the portion adjacent to the convex portion of the layer thickness regulating member and the seal member can be reduced or eliminated by the protrusion), the effect of ensuring the adhesion between the layer thickness regulating member near the convex portion and the seal member can be more appropriately obtained while suppressing the above-mentioned problems.

[0061] [Aspect 5] Aspect 5 has a toner carrier (for example, developing roller 21), a layer thickness regulating member (for example, toner layer regulating blade 24) that regulates the layer thickness of the toner on the surface of the toner carrier with a regulating portion 24b pressed against the surface of the toner carrier, and a seal member 26 disposed between the end surface 21a of the toner carrier and a seal holding surface 29a facing the end surface. The layer thickness regulating member has a convex portion (for example, bent portion 24a) on the back surface of the regulating portion, and the seal member is disposed so as to sandwich the convex portion existing at a position facing the end surface 21a of the toner carrier among the convex portions of the layer thickness regulating member between the seal member and the end surface. In the developing device 20, the seal holding surface is characterized by having a concave portion 29a3 at a position facing the convex portion. According to this aspect, when the seal member is pushed in (crushed) by the convex portion of the layer thickness regulating member, the portion of the seal member on the side opposite to the convex portion can escape into the recess of the seal holding surface. As a result, even when the seal member is pushed in (crushed) by the convex portion of the layer thickness regulating member, the amount of compression of the seal member can be kept small, and the contact pressure between the layer thickness regulating member of the convex portion and the surface of the toner carrier can be reduced. Therefore, even if the seal member is configured to contact the convex portion of the layer thickness regulating member with a strong contact pressure in order to reduce or eliminate the gap between the portion adjacent to the convex portion of the layer thickness regulating member and the seal member, the contact pressure between the layer thickness regulating member of the convex portion and the surface of the toner carrier can be kept within an appropriate range (within the range where the above problems are suppressed). As a result, while suppressing the above problems, the adhesion between the layer thickness regulating member in the vicinity of the convex portion and the seal member can be ensured.

[0062] [Aspect 6] Aspect 6 is characterized in that, in the 4th or 5th aspect, the end position on the outer side in the width direction of the toner carrier of the seal holding surface is located on the outer side in the width direction of the toner carrier than the recess. According to this, it becomes possible to adhere the seal holding surface portion on the outer side in the width direction of the toner carrier than the recess and the seal member. As a result, for example, even when the seal holding surface and the seal member are adhered while avoiding the region facing the recess on the seal holding surface and the vicinity region thereof, the seal holding surface and the seal member can be adhered over the entire region in the surface movement direction of the toner carrier, and the adhesiveness between the seal holding surface and the seal member can be maintained.

[0063] [Aspect 7] Aspect 7 is characterized in that, in any one of the 4th to 6th aspects, the end position P4 on the outer side in the width direction of the toner carrier in the recess is located on the outer side in the width direction of the toner carrier than the convex portion. According to this, the recess exists up to the position facing the end portion in the width direction of the toner carrier of the convex portion of the layer thickness regulating member, and the contact pressure between the edge portion of the layer thickness regulating member (the end portion in the width direction of the toner carrier of the layer thickness regulating member) and the end surface of the toner carrier can be released by the recess, and the generation of excessive contact pressure at the edge portion can be suppressed.

[0064] [Aspect 8] In the eighth aspect, in any one of the first to seventh aspects, the seal member is held on the seal holding surface by an adhesive layer (for example, double-sided tape 26c), and the adhesive layer is not provided at a position facing the convex portion, and at positions facing the upstream adjacent portion and the downstream adjacent portion in the surface movement direction of the toner carrier of the convex portion. According to this, even when the adhesive layer is less deformable than the seal member (for example, less likely to stretch and less likely to bend), without the adhesive layer getting in the way, while suppressing the above-mentioned problems, the effect of ensuring the adhesion between the layer thickness regulating member and the seal member in the vicinity of the convex portion can be appropriately obtained.

[0065] [Aspect 9] The ninth aspect is an image forming apparatus (for example, a printer) including a developing device 20 that develops a latent image on a latent image carrier (for example, a photoreceptor 1) with toner, and as the developing device, any one of the developing devices of the first to eighth aspects is used. According to this, it is possible to provide an image forming apparatus that can suppress the above-mentioned problems and ensure the adhesion between the layer thickness regulating member and the seal member in the vicinity of the convex portion.

Explanation of Reference Numerals

[0066] 1: Photoreceptor 2: Cleaning blade 4: Charging roller 7: Latent image writing device 9: Toner cartridge 10: Transfer roller 20: Developing device 21: Developing roller 21a: End surface 22: Toner supply roller 23A: Toner conveyance member 23B: Toner conveyance member 24: Toner layer regulating blade 24a: Bent portion 24b: Regulating portion 25: Blade support portion 26: Seal member 26a: Surface layer portion 26b: Elastic portion 26c: Double-sided tape 29: Developing case 29a: Seal holding surface 29a1: Protrusion 29a2: Protrusion 29a3: Recess 44: Fixing device 80: Control unit 100: Paper feed cassette

Prior art documents

Patent documents

[0067]

Patent Document 1

Claims

1. A toner carrier, a layer thickness regulating member that regulates the layer thickness of toner on the surface of the toner carrier by a regulating portion pressed against the surface of the toner carrier, and a seal member disposed between an end surface of the toner carrier and a seal holding surface facing the end surface, wherein the layer thickness regulating member has a convex portion on the back surface of the regulating portion, and in the developing device in which the seal member is disposed so as to sandwich a convex portion existing at a position facing the end surface of the toner carrier among the convex portions of the layer thickness regulating member between the seal member and the end surface, the seal holding surface has a protrusion at a position facing at least one of an upstream adjacent portion and a downstream adjacent portion in the moving direction of the toner carrier surface of the convex portion.

2. In the developing device according to claim 1, an end position on the outer side in the toner carrier width direction of the seal holding surface is located on the outer side in the toner carrier width direction with respect to the protrusion.

3. In the developing device according to claim 1 or 2, an end position on the outer side in the toner carrier width direction of the protrusion is located on the inner side in the toner carrier width direction with respect to the convex portion.

4. In the developing device according to claim 1 or 2, the seal holding surface has a recess at a position facing the convex portion.

5. A toner carrier, a layer thickness regulating member that regulates the layer thickness of toner on the surface of the toner carrier by a regulating portion pressed against the surface of the toner carrier, and a seal member disposed between an end surface of the toner carrier and a seal holding surface facing the end surface, wherein the layer thickness regulating member has a convex portion on the back surface of the regulating portion, and in the developing device in which the seal member is disposed so as to sandwich a convex portion existing at a position facing the end surface of the toner carrier among the convex portions of the layer thickness regulating member between the seal member and the end surface, the seal holding surface has a recess at a position facing the convex portion.

6. In the developing device according to claim 5, an end position on the outer side in the toner carrier width direction of the seal holding surface is located on the outer side in the toner carrier width direction with respect to the recess.

7. In the developing device according to claim 5 or 6, The developing device is characterized in that an end position on the outer side in the width direction of the toner carrier in the concave portion is located on the outer side in the width direction of the toner carrier than the convex portion.

8. In the developing device according to claim 1 or 5, the seal member is held on the seal holding surface by an adhesive layer, the developing device is characterized in that the adhesive layer is not provided at a location facing the convex portion and at locations facing an upstream adjacent location and a downstream adjacent location in the surface movement direction of the toner carrier of the convex portion.

9. An image forming apparatus including a developing device that develops a latent image on a latent image carrier with toner, the image forming apparatus is characterized in that the developing device according to claim 1 or 5 is used as the developing device.

Images