JP6736316B2 - Process cartridge and image forming apparatus - Google Patents

Description

The present invention relates to a process cartridge and an image forming apparatus including the process cartridge.

Here, the process cartridge is a cartridge in which a photosensitive drum and a process unit that acts on the photosensitive drum are integrally formed into a cartridge, and the cartridge is detachably attached to the apparatus main body of the image forming apparatus.

For example, a cartridge in which a photosensitive drum and at least one of a developing means, a charging means, and a cleaning means as the process means are integrated into a cartridge may be used. The image forming apparatus is an apparatus that forms an image on a recording medium using, for example, an electrophotographic image forming method.

Examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (LED printer, laser beam printer, etc.), a facsimile machine, a word processor, and the like.

In an electrophotographic image forming apparatus (hereinafter, also simply referred to as “image forming apparatus”), an electrophotographic photosensitive member which is generally a drum type as an image carrier, that is, a photosensitive drum is uniformly charged. Then, the charged photosensitive drum is selectively exposed to form an electrostatic latent image (electrostatic image) on the photosensitive drum. Next, the electrostatic latent image formed on the photosensitive drum is developed as a toner image with toner as a developer. Then, the toner image formed on the photosensitive drum is transferred to a recording material such as recording paper or a plastic sheet, and heat or pressure is applied to the toner image transferred onto the recording material to form the toner image on the recording material. Image recording is performed by fixing.

Such an image forming apparatus generally requires toner replenishment and maintenance of various process means. In order to facilitate toner replenishment and maintenance, a photosensitive drum, a charging unit, a developing unit, a cleaning unit, and the like are collectively formed into a cartridge, and a process cartridge that is detachable from the main body of the image forming apparatus is put into practical use. ing.

According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself, so that the operability can be remarkably improved and the image forming apparatus excellent in usability can be provided. Therefore, this process cartridge system is widely used in image forming apparatuses.

As the above-mentioned process cartridge, there is generally known one in which a cleaning unit that holds a photosensitive drum, a cleaning unit, and the like, and a developing unit that holds a developing roller, which is a developer carrying member, are joined by a coupling shaft. .. The coupling shafts are provided at one end portion (hereinafter, drive side) and the other end portion (hereinafter, non-drive side) in the photosensitive drum axial direction, respectively. And is rotatably supported. Further, the developing unit rotatably supported by the coupling shaft is urged toward the cleaning unit by its own weight and a pressing member such as a spring. Therefore, the developing roller in the developing unit can come into contact with both ends of the cleaning unit with a constant pressure, and the image forming apparatus can stably form an image.

However, in such a process cartridge, the position of the coupling shaft that couples the cleaning unit and the developing unit and the position of the hole that engages the coupling shaft may be different from the dimension ( , Reference dimensions). If the position of the coupling axis or the like shifts, the coupling between the cleaning unit and the developing unit will be affected. As a result, the pressure applied to the photosensitive drum by the developing roller may differ greatly between the driving side and the non-driving side.

Therefore, in the conventional process cartridge, as disclosed in Patent Document 1 or Patent Document 2, a measure is taken in which the hole on the non-driving side of the developing unit with which the coupling shaft is engaged is elongated. As a result, even if the position of the coupling member or the like deviates from the reference dimension, when the coupling member engages the elongated hole, the engagement position between the elongated hole and the coupling member moves It is possible to absorb the deviation. As a result, the pressure applied to the photosensitive drum by the developing roller becomes stable at both ends.

Japanese Patent Laid-Open No. 08-339149 JP, 09-050224, A

In recent years, it has been desired to realize a process cartridge having a larger capacity. However, in order to realize this, the amount of toner is increased and the weight of the developing unit is increased. Here, FIG. 16 shows a sectional view of the conventional process cartridge R as viewed from the non-driving side. The developing unit 90 is rotatably supported by a coupling shaft 93 fixed to the cleaning unit 92. As shown in FIG. 16, the weight of the developing unit 90 in the initial stage (toner amount full) is M1, and the weight of the developing unit 90 in the latter half of the durability (empty toner amount) is M2. At this time, M1>>M2 holds, and the gravity center positions of M1 and M2 also change from L1 to L2. As a result, the optimum long hole angle greatly differs between the long hole 91 when the toner amount is full (FIG. 16B) and the long hole 91 when the toner amount is empty (FIG. 16C). become.

Therefore, an object of the present invention is to provide a process cartridge in which the pressing force of a developer carrier such as a developing roller against an image carrier such as a photosensitive drum is stable at both ends even in a large capacity process cartridge.

In order to achieve the above-mentioned object, the present invention is a process cartridge that is attachable to and detachable from an apparatus body of an image forming apparatus, and includes a first frame body that rotatably supports an image carrier and a developing unit that faces the image carrier. A second frame body that rotatably supports the agent carrier, a coupling shaft that is fixed to the first frame body, and that rotatably couples the first frame body and the second frame body, A biasing member that biases the developer bearing member to the image bearing member, and the second frame member is fitted to the coupling shaft at one end in the axial direction of the image bearing member, a first support hole is rotatably positioned with a gap to the coupling shaft at the other end is rotatably supported in the axial direction of said image bearing member and the second support hole that having a circular shape, has, the gap between the coupling shaft of the second support hole in the radial direction of the coupling shaft, the much larger than the gap between the coupling shaft of the first support hole, in use In the posture, when viewed from the rotation axis of the image carrier, the image carrier is positioned so as to be aligned in the horizontal direction with respect to the coupling axis, and the developer carrier is located below the image carrier. Are located in a line in the horizontal direction with respect to the coupling axis, the rotation center of the developer carrier is located below the axis of the coupling axis, and the image carrier is rotated. It is characterized in that it is located below the center and the axis of the coupling shaft is located above the center of rotation of the image carrier .

According to the present invention, it is possible to provide a process cartridge in which the pressing force of the developer carrying member against the image carrying member is stable at both ends even in a large capacity process cartridge.

FIG. 3 is a cross-sectional view of a non-driving side end portion of the process cartridge according to the first embodiment. FIG. 3 is a sectional view of an image forming apparatus main body and a process cartridge of the image forming apparatus according to the first embodiment. FIG. 3 is a cross-sectional view of the process cartridge according to the first embodiment. FIG. 3 is a cross-sectional view of the inside of the cleaning container of the process cartridge according to the first embodiment. FIG. 3 is a perspective view of the image forming apparatus main body with the opening/closing door of the image forming apparatus according to the first exemplary embodiment open. FIG. 3 is a perspective view of the image forming apparatus main body in a state where the opening/closing door of the image forming apparatus according to the first embodiment is opened and the tray is pulled out. FIG. 4 is a perspective view of the image forming apparatus main body and the process cartridge when the process cartridge is attached to and detached from the tray with the opening/closing door of the image forming apparatus according to the first exemplary embodiment being opened and the tray being pulled out. FIG. 3 is a perspective view of a drive side positioning portion of the process cartridge and the image forming apparatus main body in a state where the process cartridge is attached to the image forming apparatus main body according to the first embodiment. FIG. 3 is a perspective view of a non-driving side positioning portion of the process cartridge and the image forming apparatus main body in a state where the process cartridge is attached to the image forming apparatus main body according to the first embodiment. FIG. 3 is an exploded view of the process cartridge according to the first embodiment. FIG. 3 is an exploded view of the process cartridge according to the first embodiment. FIG. 3 is an exploded view of the process cartridge according to the first embodiment. FIG. 3 is an exploded view of the process cartridge according to the first embodiment. FIG. 3 is a cross-sectional view of a driving side end portion of the process cartridge according to the first example. FIG. 11 is a partially enlarged view of a process cartridge non-driving side end portion according to another embodiment. FIG. 14 is a cross-sectional view of a conventional example of a process cartridge when viewed from a non-driving side.

Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments should be appropriately changed depending on the configuration of the device to which the present invention is applied and various conditions. Therefore, unless otherwise specified, the scope of the present invention is not intended to be limited thereto.

[Example 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the direction of the rotation axis of the electrophotographic photosensitive drum as the image carrier is the longitudinal direction. Further, in the longitudinal direction, the side where the electrophotographic photosensitive drum receives the driving force from the image forming apparatus main body is the driving side, and the opposite side is the non-driving side.

The overall configuration of the image forming apparatus including the process cartridge and the image forming process will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view of an image forming apparatus body (hereinafter, referred to as apparatus body A) and a process cartridge (hereinafter, referred to as cartridge B) of an electrophotographic image forming apparatus according to an embodiment of the present invention. .. FIG. 3 is a sectional view of the cartridge B. Here, the apparatus main body A is a portion excluding the cartridge B from the electrophotographic image forming apparatus.

<Overall structure of electrophotographic image forming apparatus>
The electrophotographic image forming apparatus shown in FIG. 2 is a laser beam printer using the electrophotographic technique in which the cartridge B is detachably attached to the apparatus main body A. When the cartridge B is attached to the apparatus main body A, the exposure device 3 (laser scanner unit) for forming a latent image on the electrophotographic photosensitive drum 62 of the cartridge B is arranged. Further, below the cartridge B, a sheet tray 4 accommodating a recording medium (hereinafter, referred to as a sheet material P) to be image-formed is arranged.

Further, in the main assembly A of the apparatus, along the conveyance direction D of the sheet material P, the pickup roller 5a, the feeding roller pair 5b, the conveyance roller pair 5c, the transfer guide 6, the transfer roller 7, the conveyance guide 8, the fixing device 9, A pair of discharge rollers 10 and a discharge tray 11 are sequentially arranged. The fixing device 9 is composed of a heating roller 9a and a pressure roller 9b.

<Image forming process>
Next, the outline of the image forming process will be described. Based on the print start signal, the electrophotographic photosensitive drum (hereinafter referred to as drum 62) is rotationally driven in the direction of arrow R at a predetermined peripheral speed (process speed).

The charging roller 66 to which the bias voltage is applied contacts the outer peripheral surface of the drum 62 and uniformly charges the outer peripheral surface of the drum 62.

The exposure device 3 outputs a laser beam L according to image information. The laser light L passes through a laser opening 71h provided in the cleaning frame 71 of the cartridge B to scan and expose the outer peripheral surface of the drum 62. As a result, an electrostatic latent image corresponding to the image information is formed on the outer peripheral surface of the drum 62.

On the other hand, as shown in FIG. 3, in the developing unit 20 as the developing device, the toner T in the toner chamber 29 is agitated and conveyed by the rotation of the first conveying member 43, the second conveying member 44, and the third conveying member 50. Then, the toner is supplied to the toner supply chamber 28.

The toner T is carried by the magnetic force of the magnet roller 34 (fixed magnet) on the surface of the developing roller 32, which is a developer carrying body and faces the drum 62. The layer thickness of the toner T on the peripheral surface of the developing roller 32 is regulated while being triboelectrically charged by the developing blade 42. The toner T is developed on the drum 62 according to the electrostatic latent image and is visualized as a toner image.

Further, as shown in FIG. 2, the sheet material P stored in the lower portion of the apparatus main body A is moved to the sheet tray by the pickup roller 5a, the feeding roller pair 5b, and the conveying roller pair 5c at the output timing of the laser light L. It is sent out from 4. Then, the sheet material P is conveyed to the transfer position between the drum 62 and the transfer roller 7 via the transfer guide 6. At this transfer position, the toner image is sequentially transferred from the drum 62 to the sheet material P.

The sheet material P to which the toner image is transferred is separated from the drum 62 and is conveyed to the fixing device 9 along the conveyance guide 8. Then, the sheet material P passes through a nip portion between the heating roller 9a and the pressure roller 9b which form the fixing device 9. The toner image is fixed on the sheet material P by performing pressure/heat fixing processing in this nip portion. The sheet material P that has undergone the toner image fixing process is conveyed to the discharge roller pair 10 and discharged to the discharge tray 11.

On the other hand, as shown in FIG. 3, the residual toner on the outer peripheral surface of the drum 62 after the transfer is removed by the cleaning member 77, and the drum 62 is used again in the image forming process. The toner removed from the drum 62 is stored in the waste toner chamber 71b of the cleaning unit 60.

In the above, the charging roller (charging means) 66, the developing roller (developing means) 32, the transfer roller (transfer means) 7, and the cleaning member (cleaning means) 77 are process means acting on the drum 62.

<Cartridge attachment/detachment>
Next, attachment/detachment of the cartridge B to/from the apparatus main body A will be described with reference to FIGS. 5 and 6.

FIG. 5 is a perspective view of the apparatus main body A in which the opening/closing door 13 is opened to attach/detach the cartridge B. FIG. 6 is a perspective view of the apparatus main body A and the cartridge B in a state in which the opening/closing door 13 is opened and the tray 18 is pulled out in order to attach/detach the cartridge B. FIG. 7 is a perspective view of the apparatus main body A and the cartridge B when the cartridge B is attached and detached with the opening/closing door 13 opened and the tray 18 pulled out. The cartridge B can be attached to and detached from the tray 18 in the attachment/detachment direction E.

An opening/closing door 13 is rotatably attached to the apparatus main body A, and a cartridge insertion opening 17 is provided when the opening/closing door 13 is opened. A tray 18 for mounting the cartridge B in the apparatus main assembly A is provided in the cartridge insertion opening 17. When the tray 18 is pulled out to a predetermined position, the cartridge B can be attached and detached. The cartridge B mounted on the tray 18 is mounted in the main assembly A of the apparatus along a guide rail (not shown) in the direction of arrow C in the drawing.

Further, the apparatus main body A is provided with a first drive shaft 14 and a second drive shaft 19 for transmitting drive to the first coupling 70 and the second coupling 21 (FIG. 8) provided in the cartridge B. ing. The first drive shaft 14 and the second drive shaft 19 are driven by a motor (not shown) of the apparatus main body A. As a result, the drum 62 connected to the first coupling 70 receives the driving force from the apparatus main body A and rotates. Further, the drive is transmitted from the second coupling 21 and the developing roller 32 rotates. Further, the charging roller 66 and the developing roller 32 are supplied with power from a power supply unit (not shown) of the apparatus main assembly A.

<Cartridge support>
As shown in FIG. 5, the apparatus main body A is provided with a driving side plate 15 and a non-driving side plate 16 for supporting the cartridge B. As shown in FIGS. 8 and 9, the drive side plate 15 is provided with a drive side first support portion 15a, a drive side second support portion 15b, and a rotation support portion 15c of the cartridge B. The non-driving side plate 16 is provided with a non-driving side first supporting portion 16a, a non-driving side second supporting portion 16b, and a rotation supporting portion 16c.

On the other hand, as supported parts of the cartridge B, a supported part 73b of the drum bearing 73, a supported part 73d, a driving side boss 71a of the cleaning frame 71, a non-driving side protrusion 71f and a non-driving side boss 71g are provided, respectively. ing. The supported portion 73b is supported by the drive-side first support portion 15a, the supported portion 73d is supported by the drive-side second support portion 15b, and the drive-side boss 71a is supported by the rotation support portion 15c. The non-driving side protrusion 71f is supported by the non-driving side first supporting portion 16a and the non-driving side second supporting portion 16b, and the non-driving side boss 71g is supported by the rotation supporting portion 16c. It is positioned in the apparatus main body A.

<Structure of entire cartridge>
Next, the overall configuration of the cartridge B will be described with reference to FIGS. 3, 4, 10, 11, 12, and 13. FIG. 3 is a sectional view of the cartridge B. 10, 11, 12, and 13 are perspective views for explaining the configuration of the cartridge B. 11 and 13 are partially enlarged views in which portions within the dotted line portions of FIGS. 10 and 12 are enlarged at different angles. In the present embodiment, description will be made while omitting screws for connecting the respective parts.

The cartridge B has a cleaning unit 60 and a developing unit 20. A process cartridge is a cartridge of an electrophotographic photosensitive member and at least one of a charging unit, a developing unit, and a cleaning unit, which act on the electrophotographic photosensitive member, and is integrally formed as a cartridge with respect to the main body of the electrophotographic image forming apparatus. It is detachable. In the present invention, the process cartridge has at least the cleaning unit 60 according to the present invention.

As shown in FIG. 3, the cleaning unit 60 includes a drum 62, a charging roller 66, a cleaning member 77, a cleaning frame 71 supporting these, and a lid member 72 fixed to the cleaning frame 71 by welding or the like. Have. In the cleaning unit 60, the charging roller 66 and the cleaning member 77 are arranged in contact with the outer peripheral surface of the drum 62, respectively.

The cleaning member 77 includes a rubber blade 77a, which is a blade-shaped elastic member formed of rubber as an elastic material, and a support member 77b that supports the rubber blade. The rubber blade 77a is in contact with the drum 62 in the counter direction with respect to the rotation direction of the drum 62. That is, the rubber blade 77a is in contact with the drum 62 so that its tip end faces the upstream side in the rotation direction of the drum 62.

FIG. 4 is a sectional view of the cleaning frame 71. As shown in FIGS. 3 and 4, the waste toner removed from the surface of the drum 62 by the cleaning member 77 has a first screw 86, a second screw 87, and a third screw 88 as a waste toner conveying member (conveying member). Transported by. Then, it is stored in a waste toner chamber 71b formed by the cleaning frame 71 and the lid member 72. Further, the first screw 86 is rotated by a drive (not shown) from the coupling 21 shown in FIG. The second screw 87 receives a driving force from the first screw 86 and the third screw 88 receives a driving force from the second screw 87, and rotates. The first screw 86 is disposed in the vicinity of the drum 62, the second screw 87 is disposed at the end of the cleaning frame 71 in the longitudinal direction, and the third screw 88 is disposed in the waste toner chamber 71b. Here, the rotation axes of the first screw 86 and the third screw 88 are parallel to the rotation axis of the drum 62, and the rotation axis of the second screw 87 is orthogonal to the rotation axis of the drum 62.

Further, as shown in FIG. 3, a squeeze sheet 65 for preventing the waste toner from leaking from the cleaning frame 71 is provided at the edge of the cleaning frame 71 so as to contact the drum 62.

The drum 62 receives a driving force from a main body driving motor (not shown) that is a driving source, and thus is rotationally driven in the direction of arrow R in the drawing in accordance with an image forming operation.

The charging roller 66 is rotatably attached to the cleaning unit 60 via charging roller bearings 67 at both ends in the longitudinal direction of the cleaning frame 71 (substantially parallel to the rotation axis direction of the drum 62 ). The charging roller 66 is pressed against the drum 62 by pressing the charging roller bearing 67 toward the drum 62 by the urging member 68. The charging roller 66 is rotated by the rotation of the drum 62.

As shown in FIG. 3, the developing unit 20 includes a developing roller 32, a developing container 23 that supports the developing roller 32, a developing blade 42, and the like. A magnet roller 34 is provided in the developing roller 32. Further, in the developing unit 20, a developing blade 42 for regulating the toner layer on the developing roller 32 is arranged. As shown in FIGS. 10 and 12, a spacing member 38 is attached to the developing roller 32 at both ends of the developing roller 32, and when the spacing member 38 and the drum 62 contact each other, the developing roller 32 faces each other. The drum 62 is held with a minute gap. Further, as shown in FIG. 3, a blowing prevention sheet 33 for preventing the toner from leaking from the developing unit 20 is provided at the edge of the bottom member 22 so as to contact the developing roller 32. Further, the toner chamber 29 formed by the developing container 23 and the bottom member 22 is provided with a first carrying member 43, a second carrying member 44, and a third carrying member 50. The first transport member 43, the second transport member 44, and the third transport member 50 stir the toner contained in the toner chamber 29 and transport the toner to the toner supply chamber 28.

As shown in FIGS. 10 and 12, the cartridge B is configured by combining the cleaning unit 60 and the developing unit 20.

The cleaning unit 60 is provided with a cleaning frame 71 as a first frame, a lid member 72, a drum 62, a drum bearing 73 for rotatably supporting the drum 62, and a drum shaft 78. As shown in FIG. 13, on the drive side, the drive side drum flange 63 provided on the drive side of the drum 62 is rotatably supported by the hole portion 73 a of the drum bearing 73. On the other hand, as shown in FIG. 11, on the non-driving side, the drum shaft 78 press-fitted into the hole portion 71c provided in the cleaning frame 71 can rotate the hole portion (not shown) of the non-driving side drum flange 64. It is configured to support. In this way, the drum 62 is rotatably supported by the cleaning frame body 71 as the first frame body and the drum bearing 73.

As shown in FIGS. 3, 10, and 12, on the other hand, the developing unit 20 includes a bottom member 22, a developing container 23 as a second frame, a driving side developing side member 26, a developing blade 42, a developing roller 32, and the like. Become. The developing roller 32 is rotatably attached to the developing container 23 as a second frame by bearing members 27 and 37 provided at both ends.

Then, as shown in FIGS. 11 and 13, the cartridge B is configured by rotatably connecting the cleaning unit 60 and the developing unit 20 to each other with a connecting pin 69 as a connecting shaft.

Specifically, at both ends of the developing unit 20 in the longitudinal direction, a developing container 23 as a second frame is provided with a developing first supporting hole 23a as a positioned hole and a developing second supporting hole 23b as a backlashed hole. It is provided. Further, at both ends in the longitudinal direction of the cleaning unit 60, a cleaning frame 71 as a first frame is provided with a first hanging hole 71i and a second hanging hole 71j. In the cartridge B, at one end portion in the axial direction of the drum 62, the connecting pin 69 as a connecting shaft press-fitted and fixed in the first hanging hole 71i and the developing first supporting hole 23a are fitted. Further, in the cartridge B, at the other end of the drum 62 in the axial direction, the connecting pin 69 as a connecting shaft press-fitted and fixed in the second hanging hole 71j and the second developing support hole 23b are engaged with each other. As a result, the cleaning unit 60 and the developing unit 20 are rotatably connected to each other.

Further, the first hole portion 46Ra of the driving side biasing member 46R is hooked on the boss 73c of the drum bearing 73, and the second hole portion 46Rb is hooked on the boss 26a of the driving side developing side member 26.

The first hole portion 46Fa of the non-driving side biasing member 46F is hooked on the boss 71k of the cleaning frame 71, and the second hole portion 46Fb is hooked on the boss 37a of the bearing member 37.

In this embodiment, the driving side urging member 46R and the non-driving side urging member 46F are formed by tension springs. By urging the developing unit 20 toward the cleaning unit 60 by the urging force of the spring, the developing roller 32 is surely pressed toward the drum 62. The developing roller 32 is held at a predetermined distance from the drum 62 by the distance holding members 38 attached to both ends of the developing roller 32.

<Structure of pressing developing roller against photosensitive drum>
The structure for pressing the developing roller against the photosensitive drum will be described in detail with reference to FIGS. 1A is a cross-sectional view (a cross-sectional view taken along line A2-A2 of FIG. 9) of the process cartridge at the non-driving side end portion, and FIGS. 1B to 1D are coupling pins 69 described in FIG. FIG. 6 is a partially enlarged view showing a second developing support hole 23b. FIG. 14A is a sectional view (a sectional view taken along line A1-A1 of FIG. 8) of the process cartridge at the drive side end portion, and FIG. 14B is a sectional view of the connecting pin 69 and the developing first support shown in FIG. 14A. It is a partial enlarged view showing a hole 23a.

First, the configuration on the drive side will be described with reference to FIGS. As described above, on the drive side, the connecting pin 69 press-fitted and fixed in the first hanging hole 71i and the developing first supporting hole 23a are fitted, and the developing unit 20 is positioned with respect to the cleaning unit 60. It is in a state. At this time, the developing roller 32 is pressed toward the drum 62 by the moment M1 due to the developing unit weight G1 and the urging force F1 due to the driving side urging member 46R (not shown in FIG. 14, see FIG. 8), and the pressing force P1 is applied. It will be. Here, FIG. 14B is a partially enlarged view showing the connecting pin 69 and the developing first supporting hole 23a, and the fitting amount of the connecting pin 69 and the developing first supporting hole 23a is t1. Here, the fitting amount t1 is a gap between the coupling pin 69 and the coupling pin (coupling shaft) 69 of the developing first support hole 23a on the driving side in the radial direction of the coupling pin 69 (FIG. 14B). reference).

Next, the configuration on the non-driving side will be described with reference to FIGS. On the non-driving side, the diameter r2 of the second developing support hole 23b is larger than the diameter r1 of the connecting pin 69, and the developing unit 20 has a backlash amount t2 (=r2-r1) with respect to the cleaning unit 60. Supported in a certain state. At this time, similarly to the driving side, the developing roller 32 is pressed toward the drum 62 by the moment M2 by the developing unit weight G2 and the urging force F2 by the non-driving side urging member 46F (not shown in FIG. 1, see FIG. 9). , The pressing force P2 is applied.

Here, when the amount of toner in the developing unit 20 is full, the developing unit 20 moves in the direction of the arrow N1 in FIG. 1(c) due to its weight, and the connecting pin 69 and the second developing support hole 23b are located in FIG. It abuts at a point c1 in (c). On the other hand, when the amount of toner in the developing unit 20 is empty, the developing unit 20 moves in the direction of the arrow N2 in FIG. 1(d), and the connecting pin 69 and the second developing support hole 23b are located in FIG. 1(d). The contact is made at the point d1. At this time, even if the developing unit 20 is moved during physical distribution or by user operation, since the backlash amount t2 is provided by the connecting pin 69 and the second developing support hole 23b, it may return to the predetermined position (c1, d1). You can

Here, the positional relationship between the coupling pin 69, the drum 62, the developing roller 32, and the third screw 88 when the cartridge B is attached to the apparatus main body A will be described with reference to FIG. To do. The state shown in FIGS. 1A and 2 is a state in which the cartridge B is attached to the apparatus main body A.

As shown in FIG. 1A, the drum 62 is positioned so as to be horizontally aligned with the coupling pin 69. The developing roller 32 is located below the drum 62, and is aligned with the connecting pin 69 in the horizontal direction. The center 32c of the developing roller 32 is located below the center 69c of the coupling pin 69 and below the center 62c of the drum 62. The center 69c of the coupling pin 69 is located above the center 62c of the drum 62 and below the center 88c of the third screw 88. The cartridge B is a process cartridge in which the positional relationship between the coupling pin 69, the drum 62, the developing roller 32, and the third screw 88 in the state of being mounted in the apparatus main body A is as described above. is there.

Next, the play amount t2 of the developing unit 20 with respect to the cleaning unit 60 on the non-driving side will be described in detail. Here, the backlash amount t2 is a gap between the coupling pin 69 and the coupling pin (coupling shaft) 69 of the second developing support hole 23b on the non-driving side in the radial direction of the coupling pin 69 (FIG. 1B). reference). More specifically, the gap t2 between the second developing support hole 23b and the connecting pin 69 is such that the center of the second developing support hole 23b and the center of the connecting pin 69 overlap each other, as shown in FIG. 1B. It is the difference between the radius r2 of the second developing support hole 23b and the radius r1 of the connecting pin 69 when viewed from above.

First, in the cleaning unit 60, the coupling pin 69 (see FIG. 14A) is press-fitted and fixed in the first hanging hole 71i (see FIG. 13), and this is used as a reference. With respect to this reference, the coupling pin 69 (see FIG. 1A) press-fitted and fixed in the second suspension hole 71j (see FIG. 11) is a3=a1+a2 (FIG. 1A) depending on the dimensional tolerance of each component. 14(a) may be displaced in the direction of the middle arrow X). Hereinafter, the connecting pin 69 press-fitted and fixed to the first suspension hole 71i on the drive side is referred to as a drive-side connecting pin, and the connecting pin 69 press-fitted and fixed to the second suspension hole 71j on the non-drive side is referred to as a non-drive-side connecting pin. .. Here, a1 (see FIG. 14A) is a dimensional tolerance of each component from the drive side coupling pin 69 to the drum 62 (direction of arrow X in FIG. 14A). Further, a2 (see FIG. 1A) is a dimensional tolerance of each component from the non-driving side coupling pin 69 to the drum 62 (direction of arrow X in FIG. 1A).

Similarly, in the developing unit 20, when the developing first supporting hole 23a is used as a reference (see FIG. 14A), the developing second supporting hole 23b (see FIG. 1A) is b3= due to the dimensional tolerance of each component. A position shift of b1+b2 (direction of arrow X in FIG. 1A and FIG. 14A) may occur. Here, b1 (see FIG. 14A) is a dimensional tolerance of each component from the first developing support hole 23a to the developing roller 32 (direction of arrow X in FIG. 14A). Further, b2 (see FIG. 1A) is a dimensional tolerance (direction of arrow X in FIG. 1A) from the second developing support hole 23b to the developing roller 32.

At this time, by setting t2=a3+b3 for the positional deviations a3 and b3, the respective positional deviations can be absorbed. That is, even if the positional displacements a3 and b3 occur, stable pressures P1 and P2 can be realized. It should be noted that here, only the positional deviation in the X direction has been described, but the positional deviations a3 and b3 may occur in all directions. However, as shown in FIG. 1B, since the developing second support hole 23b is provided with the play amount t2 in all directions with respect to the coupling pin 69, it is stable regardless of which direction displacement occurs. The applied pressures P1 and P2 can be realized.

Here, it is assumed that, for example, the play amount t2 of the developing second supporting hole 23b with respect to the connecting pin 69 is equal to the fitting amount t1 of the connecting pin 69 and the developing first supporting hole 23a (t2=t1). At this time, in order to avoid the positional deviation between the non-driving side coupling pin 69 and the second developing support hole 23b, the developing unit 20 is twisted in the directions of arrows Q1 and Q2 in FIG. 1A. Due to the twists Q1 and Q2 of the developing unit 20, the pressing force P2 is increased or decreased. As a result, the difference between the pressures P1 and P2 (P1>>P2, P1<<P2) becomes large. On the other hand, the play amount t2 of the second developing support hole 23b with respect to the connecting pin 69 is set to be larger than the positional deviation a3+b3 on the driving side and the non-driving side (t2>a3+b3). At this time, the amount of displacement that can be absorbed increases, but the amount of movement of the developing unit 20 increases during physical distribution or user operation. Therefore, there is a concern that the operability will decrease. From the above, it is desirable that the amount of backlash t2 is t2=a3+b3, which is the minimum amount capable of absorbing each positional deviation.

As described above, in this embodiment, the diameter r2 of the second developing support hole 23b is larger than the diameter r1 of the non-driving side coupling pin 69, and the play amount t2 is provided. As a result, it is possible to provide a process cartridge in which the pressing force of the developing roller against the photosensitive drum is stable at both ends even in a large capacity process cartridge.

[Other Examples]
In the above-described embodiment, the second developing support hole 23b has a circular shape. However, the same effect can be obtained with a hole having a different shape.

FIG. 15 is a partially enlarged view showing the configuration of the developing second supporting hole having a different shape. In FIG. 15A, the developing second supporting hole 81 is a square hole, and in FIG. 15B, the developing second supporting hole 82 is a fan-shaped hole. A play amount t3 to t6 is provided for the non-driving side coupling pin 69 in each hole. Here, by setting t3 to t6=t2, it becomes possible to obtain the same effect as that of the circular hole even if the hole has a different shape. It should be noted that the backlash amounts t3 to t6 of the second developing support holes 81 and 82 with respect to the non-driving side coupling pin 69 shown in FIGS. 15A and 15B are different from those of the first embodiment described above, although the holes have different shapes. The same is true. That is, the gap t3 between the developing second support hole 81 and the connecting pin 69 shown in FIG. 15A is obtained by overlapping the center of the developing second supporting hole 81 with the center of the connecting pin 69. It is the difference between the length r3 of the second developing support hole 81 to the center of the side 81a and the radius r1 of the coupling pin 69. Further, the gap t4 between the second developing support hole 81 and the connecting pin 69 shown in FIG. 15A is obtained by superposing the center of the second developing hole 81 and the center of the connecting pin 69 on each other. It is the difference between the length r4 to the center of the side 81b of the second developing support hole 81 and the radius r1 of the coupling pin 69. Further, the gap t5 between the developing second supporting hole 82 and the connecting pin 69 shown in FIG. 15B is obtained by overlapping the center of the developing second supporting hole 82 with the center of the connecting pin 69. It is the difference between the length r5 to the center of the side 82a of the second developing support hole 82 and the radius r1 of the coupling pin 69. Further, the gap t6 between the developing second support hole 82 and the connecting pin 69 shown in FIG. 15B is obtained by superimposing the center of the developing second supporting hole 82 and the center of the connecting pin 69 on each other. It is the difference between the length r6 to the center of the side 82b of the second developing support hole 82 and the radius r1 of the coupling pin 69. The center of the second developing support hole 81 is the intersection of the diagonal lines of the square. The center of the second developing support hole 82 is the intersection of the perpendicular lines from the center of the straight lines (sides 82b) on both sides connecting the arcs (sides 82a).

Further, the same effect can be obtained by a structure in which an elastic member is provided in the play formed by the non-driving side coupling pin 69 and the second developing support hole 23b.

Further, in the above-described embodiment, the cleaning frame that constitutes the cleaning unit is illustrated as the first frame that rotatably supports the image carrier, but the present invention is not limited to this. For example, another frame body may be used as long as it is a frame body that rotatably supports the image carrier, such as a frame body that forms a drum unit that does not have a cleaning member.

Further, in the above-described embodiment, the configuration in which one process cartridge is attachable to and detachable from the apparatus body of the image forming apparatus is illustrated, but the number of the cartridges used is not limited and may be appropriately changed as necessary. Just set it.

Further, in the above-described embodiment, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this, and other image forming apparatuses such as a copying machine and a facsimile machine, or a combination of these functions. It may be another image forming apparatus such as a multifunction peripheral. Further, it may be an image forming apparatus which uses a recording medium carrier and sequentially transfers the toner images of the respective colors onto the recording medium carried by the recording medium carrier. Alternatively, it is an image forming apparatus that uses an intermediate transfer member, sequentially transfers the toner images of the respective colors onto the intermediate transfer member, and collectively transfers the toner images carried on the intermediate transfer member to a recording medium. Is also good. The same effect can be obtained by applying the present invention to the process cartridges equipped in these image forming apparatuses.

A... Device body B... Cartridge P... Sheet material T... Toner a3, b3... Positional deviation r1, r2... Radius r3, r4, r5, r6... Length t1... Fitting amount (gap)
t2, t3, t4, t5, t6... Play (gap)
20... Developing unit (second frame)
23a... 1st development support hole 23b... 2nd development support hole 32... Development roller (developer carrying member)
46F, 46R... Energizing member 60... Cleaning unit (first frame)
62... Drum (image carrier)
69... Coupling pin (coupling shaft)
71... Cleaning frame 71i... First hanging hole 71j... Second hanging hole 77... Cleaning member 78... Drum shaft 86... First screw 87... Second screw 88... Third screw

Claims (7)

A process cartridge removable from the main body of the image forming apparatus,
A first frame member that rotatably supports the image carrier,
A second frame member that rotatably supports the developer carrier facing the image carrier;
A coupling shaft that is fixed to the first frame body and rotatably couples the first frame body and the second frame body,
An urging member for urging the developer carrier to the image carrier,
The second frame has a first support hole that is fitted to the coupling shaft at one end in the axial direction of the image carrier and is rotatably positioned, and an axis line of the image carrier. and a second support hole that having a pivotally supported by a circular shape with a gap in the coupling shaft at the other end in the direction,
Gap between the coupling axis of the second support hole in the radial direction of the coupling shaft, much larger than the gap between the coupling shaft of the first support hole,
When viewed from the rotation axis of the image carrier in the posture during use,
The image bearing member is positioned so as to be aligned in the horizontal direction with respect to the bonding axis, and the developer bearing member is positioned below the image bearing member and is aligned with the bonding axis in the horizontal direction. The rotation center of the developer carrying body is located below the axis of the coupling shaft, and the rotation center of the image carrying body is located below the rotation center of the image bearing body. A process cartridge, wherein the process cartridge is positioned above the center of rotation of the image carrier . The gap between the coupling shaft of the second support hole and the radius of the second support hole and the coupling shaft when the center of the second support hole and the center of the coupling shaft are viewed in an overlapping manner. The process cartridge according to claim 1, wherein the process cartridge is a difference from a radius. The process cartridge according to any one of claims 1 or 2, characterized in that a resilient member between the second support hole and the coupling shaft. The gap t2 between the second support hole and the coupling shaft is a positional deviation a3 due to the dimensional tolerance of the component from the coupling shaft to the image carrier and the component from the coupling shaft to the developer carrier. a process cartridge according to any one of claims 1 to 3, wherein the relative positional deviation b3 due to dimensional tolerances, is t2 = a3 + b3. The first support hole is provided on the drive side where the image carrier receives a driving force from the apparatus main body, and the second support hole is on the side opposite to the drive side in the axial direction of the image carrier. The process cartridge according to any one of claims 1 to 4 , wherein the process cartridge is provided on a non-driving side. The first frame further has a cleaning member that removes the developer from the image carrier, and a transport member that transports the developer removed by the cleaning member,
The center of the coupling shaft is located above the center of the image carrier and below the center of the conveying member when mounted on the apparatus body of the image forming apparatus. 6. The process cartridge according to any one of items 5 to 5 . The process cartridge is detachably mountable to the apparatus main body, an image forming apparatus for forming an image on a recording medium, image formation, characterized in that it comprises a process cartridge according to any one of claims 1 to 6 apparatus.

Images