Developing device, process cartridge and image forming apparatus

Abstract

To provide a developing device that can ensure the strength of a cover part 120 and prevent deterioration of drive transmission members.SOLUTION: A developing device has a cover part 120 that covers a plurality of drive transmission members 114, 115 on the outside of a side wall part of a developer storage part. The cover part 120 has a cover side wall part and cover bottom wall parts 121, 122, and the cover bottom wall parts 121, 122 have two or more through holes 121a, 122a formed in correspondence with, of the plurality of drive transmission members 114, 115, two or more drive transmission members opposite to a bottom face. A developer receiving part 130 may be provided below the through holes 121a, 122a.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a developing device, a process cartridge, and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a developing device is known that has a cover portion that covers a plurality of drive transmission members on the outer side wall of a developer container. For example, Patent Document 1 discloses a developing device that includes a face plate (cover portion) that covers a gear train (plurality of drive transmission members) of the developing device. Summary of the Invention [Problem to be solved by the invention]

[0003] However, there is still room for improvement in terms of ensuring the strength of the cover portion and suppressing deterioration of the drive transmission members. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, the present invention provides a developing device having a cover portion that covers multiple drive transmission members on the outside of a side wall portion of a developer accommodating portion, the cover portion having a cover side wall portion and a cover bottom wall portion, and the cover bottom wall portion having two or more through holes formed to correspond to two or more drive transmission members that face the bottom surface among the multiple drive transmission members. Effect of the Invention

[0005] According to the present invention, it is possible to ensure the strength of the cover portion and to suppress deterioration of the drive transmission member. [Brief description of the drawings]

[0006] [Figure 1] FIG. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an internal configuration of the process unit shown in FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 13 is an explanatory diagram of a copying machine having another configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment will be described in which the present invention is applied to a copying machine (hereinafter, referred to as "copying machine 100") that executes an electrophotographic process as an image forming apparatus. 1 is a schematic diagram of a copying machine 100. The copying machine 100 includes a printer section 20, a paper feed section 60 disposed below the printer section 20, and an image reading section 40 disposed above the printer section 20. The printer section 20 includes a process unit 10 serving as a process cartridge integrally including a photoconductor 11 serving as a drum-shaped latent image carrier and a developing device 13 serving as developing means (described later), and a transfer unit 30 having a transfer roller 31 serving as transfer means.

[0008] On the left side of the process unit 10 in FIG. 1, there is provided an optical writing device 50 which is a latent image forming means. A toner bottle 93 for storing toner (fresh toner) to be supplied to the developing device of the process unit 10 is provided above the optical writing device 50. A waste toner bottle 94 for storing toner collected by the collection means of the process unit 10 is provided below the optical writing device 50. A fixing device 80 is provided above the transfer nip where the photoconductor 11 and the transfer roller 31 face each other. The paper feed section 60 includes a paper feed tray 61(a, b) in which paper P as a recording medium is stored in a stacked manner, a pair of paper feed rollers 70(a, b), a pair of transport rollers 71(a, b), etc.

[0009] During image formation, in the printer unit 20, an electrostatic latent image is formed on the surface of the photoconductor 11 by exposure light irradiated from the optical writing device 50 based on image information (image data) read by the image reading unit 40 or image information input from an external device. This electrostatic latent image is visualized as a toner image by the developing device 13.

[0010] Meanwhile, in the paper feed section 60, a pickup roller feeds paper P one sheet at a time from any of the selected paper feed trays 61. Then, the paper P is transported toward a pair of registration rollers 72 by a pair of paper feed rollers 70(a, b) and a pair of transport rollers 71(a, b). After the paper P reaches the pair of registration rollers 72, any skew is corrected, and the paper P is sent to the transfer nip at a timing when its position coincides with the toner image on the photoconductor 11.

[0011] At the transfer nip, a transfer bias is applied to the transfer roller 31, and the toner image on the photoconductor 11 is transferred to the paper P by electrostatic force. The paper P with the transferred toner image is sent to the fixing device 80, where the toner image is fixed to the paper P by heat and pressure. The paper P with the fixed toner image is discharged by a pair of discharge rollers 91 to a paper discharge tray 92 located below the image reading unit 40 and stacked there.

[0012] Fig. 2 is a cross-sectional view for explaining the internal configuration of the process unit 10 shown in Fig. 1. As shown in Fig. 2, the process unit 10 includes a charging member 12, a developing device 13, and a cleaning unit 14 in addition to the photoconductor 11. The charging member 12 uniformly charges the surface of the photoconductor 11 prior to the exposure process by the optical writing device 50 shown in Fig. 1, and the cleaning unit 14 cleans the surface of the photoconductor 11 after transfer at the transfer nip shown in the figure. The toner removed from the surface of the photoconductor 11 by cleaning in the cleaning unit 14 is transported by a recovered toner transport screw 15 and transported as recovered toner to a waste toner bottle 94 shown in Fig. 1, or supplied as recycled toner to the developing device 13.

[0013] The developing device 13 includes a casing 5, which is a developer container that contains a dry two-component developer consisting of a carrier and a toner. The casing 5 is composed of a lower case 5a that contains the developer, and an upper case 5b that covers the opening side of the lower case 5a. The lower case 5a is provided with a supply screw 1 and an agitating screw 2 as transport members that transport the developer in the casing 5 while stirring it.

[0014] The upper case 5b holds the developing roller 3, which is a developer carrier, and a plate-shaped doctor blade 4, which serves as a developer regulating member that regulates the layer thickness (amount) of the developer on the developing roller 3. The developing roller 3 carries the developer on its surface and rotates in the direction indicated by arrow A in Fig. 2, supplying the toner in the developer to the photoconductor 11, which is disposed opposite and rotates in the direction indicated by arrow B in Fig. 2. The doctor blade 4 is fixed to the upper case 5b of the casing 5 so as to form a development gap of a certain interval between the surface of the developing roller 3 and the doctor blade 4.

[0015] The interior of the lower case 5a is divided by a partition plate 23 into a supply passage 21 in which the supply screw 1 is disposed and an agitation passage 22 in which the agitation screw 2 is disposed. The supply screw 1 and the agitation screw 2 are rotatably supported in the lower case 5a by a supply bearing and an agitation bearing, respectively. A rear opening and a front opening are formed at the rear end and the front end in the longitudinal direction of the partition plate 23, respectively, and the supply passage 21 and the agitation passage 22 communicate with each other through these two openings. A path is formed through which the developer circulates between the supply passage 21 and the agitation passage 22 in the developing device 13.

[0016] The developer in the supply path 21 is transported in the axial direction by the rotation of the supply screw 1, and is pumped up by the magnetic force of the magnet roller inside the developing roller 3, and is supplied onto the surface of the developing roller 3. The developer pumped up onto the surface of the developing roller 3 is regulated to a certain height (layer thickness) by the doctor blade 4, and is used to develop the electrostatic latent image on the surface of the photoconductor 11 in the development area. The developer on the surface of the developing roller 3 that has passed through the development area is separated from the surface of the developing roller 3 by the action of a separation pole formed by the magnetic force of the magnet roller, and returns into the supply path 21.

[0017] Fig. 3 is a view of the drive transmission system of the developing device seen from the rear, with Fig. 1 being the front view. A developing roller gear 110 is fixed to the developing roller shaft 110a. The developing roller shaft 110a extends rearward beyond the attachment point of the developing roller gear 110, and the extended tip engages with a coupling that is rotated by a drive source arranged on the copier body side, thereby transmitting drive force.

[0018] The developing roller gear 110 meshes with a first idler gear 111. This first idler gear 111 is rotatably attached to a developing roller unit 112 in which the developing roller 3 and the doctor blade 4 are held by a common side plate 112a. A supply screw gear 115 fixed to a supply screw shaft 115a and a second idler gear 113 mesh with the first idler gear 111. The second idler gear 113 is rotatably held by a stud 113a protruding from the outside of the rear end wall of the part of the upper case 5b that corresponds to the cover above the mixing screw 2. The rear end of this stud 113a is supported by the upper end of an upward protruding part 120b of the rear wall part of a gear cover 120 formed integrally with the lower case 5a. An agitating screw gear 114 fixed to an agitating screw shaft 114a meshes with this second idler gear 113.

[0019] 3(b) is a top view of the gear cover 120 formed integrally with the lower case 5a with the upper case 5b removed. The gear cover 120 has bottom walls 122, 121 below the supply screw gear 115 and below the mixing screw gear 114. The top surfaces of the bottom walls 122, 121 have an arc-shaped cross section close to the cutting edges of the gears. These bottom walls correspond to the cover side wall portion located outside the drive transmission member in the axial direction of the rotor, and the cover bottom wall portion connecting the end wall of the developing unit case and the side wall portion below the drive transmission member.

[0020] In addition, reference numeral 120a in Fig. 3 indicates the upper surface of the gear cover 120. In the illustrated example, the height of the upper surface is the center height of the supply screw shaft 115a and the mixing screw shaft 114a. For this reason, the gear cover 120 alone can only cover the lower half of these gears. The remaining upper half and other upper gears can be covered by another member, for example, a cover portion formed integrally with the upper case 5b. This cover portion is formed with a through hole or a relief portion through which the developing roller shaft 110a protrudes for drive input.

[0021] Such a gear cover is provided for the following purposes: to protect the gears, to prevent direct contact with the gears for safety, to prevent the gears from being dirty by touching them if they are coated with a lubricant such as grease, to support the idler shaft at both ends if an idler gear is provided, etc. It is preferable that the gear cover is formed integrally with the developing case in order to reduce costs and increase strength.

[0022] In order to reduce costs, the gear cover formed integrally with the developing case by resin molding or the like is often bag-shaped with an open top and a peripheral wall and a bottom wall. In this case, when developer leaks from the seal section, bearing section, or upper cleaning section of the developing device, the developer accumulates on the bottom wall of the bag-shaped gear cover, causing problems in the following order: the developer leaks, the developer accumulates on the upper surface of the bottom wall and adheres to the gear, the developer becomes an abrasive and wears out the gear, and the gear is damaged.

[0023] Therefore, in this embodiment, two or more through holes are provided in the bottom wall of the gear cover, each of which corresponds to two or more of the drive transmission members that face the bottom surface among the multiple drive transmission members. The through holes are preferably of a diameter that is large enough that fingers cannot enter, for example, about 5 mm. They are preferably formed below the gears, or at the lowest point of the entire bottom wall of the developing case. Even if developer leaks from various places, the developer falls from the through holes in the bottom surface of the developing case that covers the various developing gears, so that the gaps between the gears and the developer are not filled with developer. It is preferable to provide a developer receiving portion below the through holes.

[0024] FIG. 4 is an explanatory diagram of one configuration example. FIG. 4(a) is an explanatory diagram from the back, FIG. 4(b) is a diagram of the gear cover 120 as seen from above, and FIG. 4(c) is a perspective view of a receiver 130 as a developer receiver below the through hole. Through holes 122a, 121a are formed in the bottom walls 122, 121. The entire top surface of this receiver 130 is open. The receiver 130 may be fixed to the developing device or may be detachable. Providing a developer receiver ensures a place to store the developer. In addition, if the developer receiver is detachable, the accumulated developer can be easily disposed of.

[0025] FIG. 5 is an explanatory diagram of another configuration example. In the configuration example of FIG. 5(a), the developer receiving portion has a ceiling portion 131a with receiving holes 131b, 131c larger than the through holes, and is also removable. A perspective view is also shown on the right. As for the holes through which the developer passes, the lower holes are slightly larger than the opposing upper holes, and all holes other than the holes through which the developer passes are closed, so that the developer is less likely to scatter than if the opening of the developer receiving portion is fully open. In the figure, 121b and 122b indicate guide pipe portions extending downward from the through holes in the bottom wall.

[0026] The configuration example of Fig. 5(b) is an example in which the developer receiving portion provided below the through-hole is provided on the image forming apparatus main body side. In the illustrated example, the developer receiving portion has a ceiling portion 131a with receiving holes 131b, 131c larger than the through-holes 121a, 122a, and is removable. A perspective view is also shown on the right. Alternatively, a receiving tray without a ceiling portion may be used as shown in Fig. 4(c). The guide pipe portion with 121b and 122b in the figure extends to the developing device installation level 20a (for example, the height of the installation surface) of the copier main body. The receiving tray 131 is placed below it.

[0027] Although the copying machine 100 described below is a monochrome copying machine, the present invention can also be applied to a color copying machine equipped with a plurality of developing devices or process cartridges. Fig. 6 is a schematic diagram of the copying machine 100. The copying machine 100 is composed of a copying machine main body (hereinafter referred to as a printer unit 20), a paper feed table (hereinafter referred to as a paper feed unit 60), and a scanner (hereinafter referred to as an image reading unit 40) that is attached to the printer unit 20.

[0028] The printer section 20 includes four process units 10 (Y, M, C, K), an intermediate transfer belt 200, an optical writing device 50 as an exposure means, a fixing device 80 as a fixing means, etc. The intermediate transfer belt 200 is an intermediate transfer body that is stretched around a plurality of tension rollers and moves in the direction of arrow A in FIG. The subscripts Y, M, C, and K added after the reference numbers of the four process units 10 indicate that they are for yellow, magenta, cyan, and black. The four process units 10 (Y, M, C, and K) have almost the same configuration except for the toner colors they use, so the following description will omit the subscripts Y, M, C, and K.

[0029] The process unit 10 is configured as a unit by integrally supporting a photoconductor 11 serving as a latent image carrier, a charging member 12 serving as a charging means, a developing device 13 serving as a developing means, and a cleaning section 14 serving as a cleaning means.

[0030] The photoconductor 11 rotates in a clockwise direction in the figure, as indicated by the arrow in the figure. The charging member 12 is in pressure contact with the surface of the photoconductor 11, and is rotated by the rotation of the photoconductor 11. The charging member 12 charges the surface of the photoconductor 11 during image formation.

[0031] The optical writing device 50 exposes the surface of the photoreceptor 11 based on image information of the original image read by the image reading unit 40 or image information input from an external device such as a personal computer, and forms an electrostatic latent image on the surface of the photoreceptor 11. The cleaning unit 14 cleans the transfer residual toner remaining on the surface of the photoreceptor 11 that has passed a position facing the intermediate transfer belt 200.

[0032] The four process units 10 form toner images of each color, yellow, cyan, magenta, and black, on the photoconductors 11. The four process units 10 are arranged in parallel in the direction in which the surface of the intermediate transfer belt 200 moves, and transfer the toner images formed on the respective photoconductors 11 to the intermediate transfer belt 200 in order to be superimposed on top of each other, thereby forming a visible image on the intermediate transfer belt 200.

[0033] A transfer roller 31 serving as a primary transfer means is disposed at a position facing each photoconductor 11 with the intermediate transfer belt 200 interposed therebetween. A primary transfer bias is applied to the transfer roller 31, forming a primary transfer electric field between the photoconductor 11 and the transfer roller 31. This primary transfer electric field transfers the toner image formed on the surface of the photoconductor 11 onto the surface of the intermediate transfer belt 200. The copier 100 forms a full-color image on the surface of the intermediate transfer belt 200 by transferring toner images of each color in succession, superimposed on top of each other, onto the surface of the moving intermediate transfer belt 200.

[0034] A secondary transfer roller 201 is disposed downstream in the surface movement direction of the intermediate transfer belt 200 from a position where the four process units 10 face the intermediate transfer belt 200. The secondary transfer roller 201 is disposed at a position facing a secondary transfer opposing roller 201a, which is one of the tension rollers, across the intermediate transfer belt 200, and forms a secondary transfer nip between the secondary transfer roller 201 and the intermediate transfer belt 200. The copier 100 applies a predetermined voltage between the secondary transfer roller 201 and the secondary transfer opposing roller 201a to form a secondary transfer electric field.

[0035] Paper P, which is a transfer material that is fed from paper feed trays 61a and 61b of paper feed unit 60 and transported in the direction of arrow S in Fig. 6, passes through the secondary transfer nip. When this paper P passes through the secondary transfer nip, a full-color image formed on the surface of intermediate transfer belt 200 is transferred to paper P by a secondary transfer electric field formed between secondary transfer roller 201 and secondary transfer opposing roller 201a.

[0036] A fixing device 80 is disposed downstream of the secondary transfer nip in the transport direction of the paper P. The paper P that has passed through the secondary transfer nip reaches the fixing device 80. The full-color image transferred onto the paper P is then fixed by heat and pressure in the fixing device 80, and the paper P with the fixed image is outputted outside the copier 100. On the other hand, the toner that is not transferred to the paper P at the secondary transfer nip and remains on the surface of the intermediate transfer belt 200 is collected by a transfer belt cleaning device 202 .

[0037] 6, toner bottles 93 (Y, M, C, K) containing toner of each color are detachably disposed above the intermediate transfer belt 200. The toner contained in the toner bottles 93 of each color is supplied to the developing device 13 of each color.

[0038] In an image forming apparatus equipped with a plurality of developing devices or process cartridges each including a developing device, the developer receiving portion may be shared by at least two of the plurality of developing devices or process cartridges.

[0039] As described above, in this embodiment, in a developing device including a drive transmission member arranged on the outside of an end wall of a developing device case having a developer storage unit with a rotating member inside, and a cover portion covering the drive transmission member, the cover portion has a cover side wall portion located outside the axial direction of the rotating body from the drive transmission member, and a cover bottom wall portion connecting the end wall of the developing device case and the side wall portion below the drive transmission member. The strength of the cover portion can be ensured by this cover bottom wall portion. The drive transmission members are provided in multiple positions on the cover bottom wall portion so as to face each other from above, and the cover bottom wall portion has through holes formed corresponding to each of the multiple drive transmission members. Since the developer can fall from the through holes, deterioration of the drive transmission member due to developer accumulating on the cover side wall portion can be suppressed. [Explanation of symbols]

[0040] 1: Supply screw 2: Mixing screw 3: Developing roller 4: Doctor Blade 5: Casing 5a: Lower case 5b: Upper case 10: Process unit 11: Photoreceptor 12: Electrostatic member 13: Developing device 14: Cleaning section 15: Collected toner transport screw 20: Printer section 20a: Developing device installation level 21: Supply route 22: Mixing channel 23: Partition plate 30: Transcription unit 31: Transfer roller 40: Image reading unit 50: Optical writing device 60:Paper feed section 61: Paper feed tray 61a: Paper feed tray 61b: Paper feed tray 70: Paper feed roller pair 71: Transport roller pair 72: Registration roller pair 80: Fixing device 91: Paper discharge roller pair 92: Output tray 93: Toner bottle 94: Waste toner bottle 100: Copy machine 110: Developing roller gear 110a: developing roller shaft 111: First idler gear 112: Developing roller unit 112a: Common side plate 113: Second idler gear 113a : Stud 114: Mixing screw gear 114a: Agitating screw shaft 115: Supply screw gear 115a: Supply screw shaft 120: Gear cover 120b:Protrusion 121: Bottom wall 121a: Through hole 122: Bottom wall 122a: Through hole 130: Tray 131: Tray 131a: Ceiling part 131b:Reception hole 131c: Receiving hole 200: Intermediate transfer belt 201: Secondary transfer roller 201a: Secondary transfer opposing roller 202: Transfer belt cleaning device A: Arrow B: Arrow P:Paper S: Arrow [Prior art documents] [Patent documents]

[0041] [Patent Document 1] JP 2014-09265 A

Claims

1. In a developing device having a cover portion for covering a plurality of drive transmission members on the outer side of a side wall portion of a developer accommodating portion, The cover portion has a cover side wall portion and a cover bottom wall portion, a bottom wall portion of the cover having two or more through holes formed in correspondence with two or more of the drive transmission members that face the bottom surface of the developing device;

2. 2. The developing device according to claim 1, The developing device further comprises a developer receiving portion provided below the through hole.

3. 3. The developing device according to claim 2, The developing device, wherein the developer receiving portion has a ceiling portion provided with a receiving hole larger than the through hole.

4. 4. The developing device according to claim 2, The developing device, wherein the developer receiving portion is detachable.

5. 5. The developing device according to claim 1, a developing device comprising a developing case in which the developer container and the cover are integrally formed.

6. 6. A process cartridge integrally comprising the developing device according to claim 1 and at least one other device used in an electrophotographic process.

7. 7. An image forming apparatus comprising: the developing device according to claim 1; or the process cartridge according to claim 6.

8. 8. The image forming apparatus according to claim 7, The image forming apparatus according to claim 1, wherein a developer receiving portion provided below the through hole is provided on a main body side of the image forming apparatus.

9. 9. The image forming apparatus according to claim 7, An image forming apparatus comprising a plurality of the developing devices or the process cartridges.

10. 9. The image forming apparatus according to claim 8, a plurality of the developing devices or the process cartridges; The image forming apparatus is characterized in that the developer receiving portion is shared by at least two of the plurality of developing devices or process cartridges.

Images