Process cartridge, photoreceptor unit, and developing unit

Abstract

To provide a process cartridge capable of improving at least either of a photoreceptor unit and a development unit constituting the process cartridge.SOLUTION: The process cartridge includes: a photoreceptor 61; a transfer roller 63; a first gear 65 and a second gear 66 that are provided at one end of the photoreceptor 61 with respect to the axial direction of the photoreceptor 61; and a third gear 67 provided at one end of the transfer roller 63 being meshed with the second gear 66 with respect to the axial direction of the photoreceptor 61. Each of the first gear 65, the second gear 66, and the third gear 67 is an oblique tooth gear; the tilting direction of the oblique teeth of the first gear 65 and the tilting direction of the oblique teeth of the second gear 66 are opposite; and the tilting direction of the oblique teeth of the first gear 65 and the tilting direction of the oblique teeth of the third gear 67 are the same.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to cartridges such as a photoreceptor unit and a developing unit that can be attached to or detached from an electrophotographic image forming apparatus.

Background Art

[0002] In a laser beam printer or a copying machine as an electrophotographic image forming apparatus, an image is formed on a recording material by forming a toner image on a photosensitive drum and transferring this toner image to a sheet as the recording material.

[0003] In a laser beam printer, in order to facilitate maintenance, a method is widely adopted in which some parts of the image forming apparatus are provided in a cartridge, the cartridge is taken out of the apparatus main body, and maintenance and replacement are performed. Patent Document 1 discloses a process cartridge in which a developing unit for storing toner in a photoreceptor unit having a photosensitive drum is detachable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a process cartridge having a detachable structure of a developing unit that stores toner in a photoreceptor unit having a photosensitive drum, there is still room for improvement in terms of size, cost, accuracy, usability, etc. The present disclosure aims to improve at least one of the photoreceptor unit and the developing unit that constitute the process cartridge.

Means for Solving the Problems

[0006] One of the inventions according to the present application is as follows. A process cartridge, comprising: a drum unit having a photosensitive drum rotatable about a rotation axis extending in the axial direction, a drum frame supporting the photosensitive drum, a pressing member, and a lever rotatable with respect to the drum frame; a developing unit detachable from the drum frame, the developing unit having a developing roller and a developing frame supporting the developing roller, wherein, in a state where the developing unit is mounted on the drum frame, the developing roller is pressed against the photosensitive drum by pressing the developing frame with the pressing member; and in a state where the developing unit is mounted on the drum frame, the lever is configured to be able to contact the developing unit; when the drum unit is placed on a horizontal plane in a state where the developing unit is mounted on the drum frame, when viewed in the vertical direction, the lever and the pressing member at least partially overlap. and The developing frame includes a side wall extending in a direction intersecting the axial direction of the developing roller, a protruding portion protruding from the side wall in the axial direction, and a portion to be pressed that is pressed by the pressing member. The portion to be pressed is provided at a position away from the protruding portion, the lever is capable of abutting against the protruding portion A process cartridge characterized by the above.

Advantages of the Invention

[0007] The present disclosure can improve at least one of a photoreceptor unit and a developing unit.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

[0009] [First Embodiment] The first embodiment of the present invention will be described in detail with appropriate reference to the drawings.

[0010] In the following description, directions are defined based on the user who uses the image forming apparatus 1. That is, the front side of the image forming apparatus 1 is defined as "front", the back side as "rear", the upper surface (top surface) side as "upper", and the lower surface (bottom surface) side as "lower". Also, when viewing the image forming apparatus 1 from the front side, the left side of the image forming apparatus 1 is defined as "left" and the right side as "right". Regarding the process cartridge 5 as well, directions are defined in the same manner as the image forming apparatus 1 assuming the same posture as when it is mounted on the image forming apparatus 1. Each direction in each drawing is defined by the arrow shown in the drawing. The front-rear direction, the up-down direction, and the left-right direction indicated by this arrow are directions orthogonal to each other. These directions indicate the same directions in all the drawings. The up-down direction is parallel to the vertical direction, and the left-right direction and the front-rear direction are parallel to the horizontal direction. Also, the left-right direction is parallel to the rotation axis direction of the photosensitive drum 61 and the rotation axis direction of the developing roller 71, respectively. Further, what is formed by integrating the developing unit 7 with the photosensitive unit 6 is referred to as the process cartridge 5. The insertion direction (mounting direction) S1 and the removal direction S2 when mounting this process cartridge 5 on the apparatus main body 2 are parallel to the front-rear direction and orthogonal to the left-right direction and the up-down direction.

[0011] <Overall Configuration of Image Forming Apparatus> FIG. 1 is a cross-sectional view of the image forming apparatus 1 with the process cartridge 5 mounted thereon, and the cross-section is parallel to the up-down direction and the front-rear direction. As shown in FIG. 1, the image forming apparatus 1 mainly includes a paper feeding unit 3 for feeding the paper S into the apparatus main body 2, an exposure device 4, a process cartridge 5 for transferring a toner image onto the paper S, and a fixing device 8 for thermally fixing the toner image transferred onto the paper S.

[0012] The paper feeding unit 3 is provided at the lower part inside the apparatus main body 2 and mainly includes a paper feeding tray 31 and a paper feeding mechanism 32. The paper S stored in the paper feeding tray 31 is fed by the paper feeding mechanism 32 toward the process cartridge 5 (between the photosensitive drum 61 and the transfer roller 63).

[0013] The exposure device 4 is disposed at the upper part within the device main body 2, and includes a laser light emitting unit (not shown), a polygon mirror (not shown with reference numerals), a lens, a reflecting mirror, etc. In this exposure device 4, the laser light based on the image data emitted from the laser light emitting unit is scanned at high speed on the surface of the photosensitive drum 61, thereby exposing the surface of the photosensitive drum 61.

[0014] The process cartridge 5 is disposed below the exposure device 4. When the door (opening / closing member) 21 provided on the device main body 2 is opened (described by a two-dot chain line in FIG. 1), it is inserted into the accommodating portion 23 of the device main body 2 in the insertion direction S1 from the opening that can be formed, and is configured to be mounted on the device main body 2. When removing the process cartridge 5 from the device main body 2, the process cartridge 5 is moved in the removal direction S2 and taken out.

[0015] This process cartridge 5 mainly includes a photoreceptor unit 6 and a developing unit 7. The photoreceptor unit 6 mainly includes a photosensitive drum 61, a charging roller 62, and a transfer roller 63. The developing unit 7 is configured to be detachably mounted on the photoreceptor unit 6. The developing unit 7 mainly includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, a toner accommodating portion (developer accommodating portion) 74 that accommodates toner (developer), and a first agitator 75A and a second agitator 75B provided in the toner accommodating portion 74.

[0016] <Image forming process> Next, the image forming process using this process cartridge 5 will be described. The photosensitive drum 61 is rotationally driven during the execution of the image forming process. First, the surface of the photosensitive drum 61 is uniformly charged by the charging roller 62, and then, by being exposed with the laser light corresponding to the image data emitted from the exposure device 4, an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 61.

[0017] On the other hand, the toner in the toner container 74 is agitated by the second agitator 75B and the first agitator 75A, and then supplied to the developing roller 71 via the supply roller 72. Then, the toner supplied to the developing roller 71 enters between the developing roller 71 and the layer thickness regulating blade 73 and is carried on the developing roller 71 as a thin layer of a certain thickness.

[0018] The toner carried on the developing roller 71 is supplied to the electrostatic latent image formed on the photosensitive drum 61. As a result, the toner adheres to the electrostatic latent image and is visualized, and a toner image is formed on the photosensitive drum 61. Then, the paper S is conveyed between the photosensitive drum 61 and the transfer roller 63, and the toner image on the photosensitive drum 61 is transferred onto the paper S.

[0019] The fixing device 8 is disposed behind the process cartridge 5 and mainly includes a heating roller 81 and a pressure roller 82. The paper S onto which the toner image is transferred passes through this fixing device 8. At this time, the paper S is heated and pressurized between the heating roller 81 and the pressure roller 82, and the toner image is fixed onto the paper S. The paper S that has passed through the fixing device 8 is discharged onto the paper discharge tray 22.

[0020] <Configuration of the process cartridge> Next, each unit of the process cartridge 5 will be described. As described above, the process cartridge 5 includes a photosensitive unit 6 and a developing unit 7 that is detachable from the photosensitive unit 6.

[0021] <Configuration of the developing unit> First, the configuration of the developing unit 7 will be described. FIG. 2 is a cross-sectional view of the developing unit 7, where (a) is a cross-sectional view taken along the A-A section of FIG. 3, and (b) is a cross-sectional view taken along the B-B section of FIG. 3. Note that the A-A section and the B-B section are parallel to the vertical direction and the front-rear direction. FIG. 3 is a perspective view of the developing unit 7. FIG. 4 is an exploded perspective view of the developing unit 7. FIG. 5 is a cross-sectional view of the developing unit 7 mounted on the photoreceptor unit 6, and the cross-section is parallel to the vertical direction and the front-rear direction. FIG. 6 is a top view of the developing unit 7, showing a state where the top surface of the housing 700 is removed for explanation. FIG. 13 is a perspective view of the developing unit 7 seen from below.

[0022] As shown in FIGS. 2(a) and 2(b), the developing unit 7 has a gripping portion 701 for the user to grip in front of the housing 700 as a developing frame body, and a developing roller 71 is rotatably supported at the rear. Hereinafter, regarding the configuration of the developing unit 7, the description will be made by referring to the axial direction along the rotation axis of the developing roller 71 as the axial direction.

[0023] The gripping portion 701 is arranged at a position overlapping the housing 700 when viewed in a cross-section perpendicular to the axial direction. Also, in the axial direction, it is arranged at approximately the central portion of the housing 700. That is, as shown in FIG. 3, in the axial direction, the gripping portion 701 is arranged between the first housing portion 700A and the second housing portion 700B that have spaces 700A1 and 700B1 for accommodating toner inside. Note that the space 700A1 is the internal space of the first housing portion 700A, and since it has the same arrangement relationship as the second housing portion 700B and the space 700B1 shown in FIG. 2(b), it is not shown.

[0024] With such a configuration, the space around the gripping portion 701 can be used as a toner storage space. When there are restrictions on the width of the developing unit in the front-rear direction in this way, by adopting this configuration, more toner can be stored. Note that when viewed in a cross-section orthogonal to the axial direction, the above-described effect can be obtained if at least a part of the gripping portion 701 overlaps with the first housing portion 700A and the second housing portion 700B. In order to accommodate more toner, it is desirable that the axial length of the gripping portion 701 be as small as possible without impairing usability.

[0025] As shown in FIGS. 4 and 6, the developing roller 71, the supply roller 72, the first agitator (first stirring member) 75A, and the second agitator (second stirring member) 75B are each rotatably supported at both ends thereof by the left side wall 704 and the right side wall 705 of the housing 700. To the left of the left side wall 704 of the housing 700, a developing coupling 710, a developing roller gear 711, a supply roller gear 712, a first agitator gear 713, a second agitator gear 714, and idler gears 715A, 715B, 715C are provided. The developing roller gear 711 is fixed to the end of the developing roller 71, and the supply roller gear 712 is fixed to the end of the supply roller 72. Further, the first agitator gear 713 is fixed to the end of the stirring rod 78A (see FIG. 5) of the first agitator 75A, and the second agitator gear 714 is fixed to the end of the stirring rod 78B (see FIG. 5) of the second agitator 75B.

[0026] In conjunction with the operation of closing the door 21 provided on the apparatus main body 2, an unillustrated developing drive transmission member provided on the apparatus main body 2 moves to a position for engaging with the developing coupling 710. Conversely, in conjunction with the operation of opening the door 21, the developing drive transmission member moves to a position for releasing the engagement with the developing coupling 710.

[0027] When the door 21 is closed, a driving force is transmitted (input) from the developing drive transmission member to the developing coupling 710 as a driving force receiving member. The developing roller 71 is rotatable via the developing roller gear 711 from the gear provided on the circumferential surface of the developing coupling 710, and the supply roller 72 is rotatable via the supply roller gear 712. The developing drive transmission member is configured to allow displacement within a predetermined range of the developing coupling 710 and transmit the driving force to the developing coupling 710. The developing coupling 710, the developing roller gear 711, and the supply roller gear 712 are restricted from moving in the axial direction by a side holder 719 attached to the housing 700.

[0028] In order to reduce the height of the apparatus main body 2 while accommodating more toner, it is important to reduce the height of the developing unit 7. Therefore, as shown in FIG. 5, it is necessary to arrange the developing unit 7 in a substantially horizontal state when the developing unit 7 is attached to the photosensitive unit 6. The developing unit 7 employs two first agitators 75A and second agitators 75B to stir the toner in the toner storage portion 74 so that it can be used up to the last. The first agitator 75A includes a stirring rod 78A and a stirring sheet 79A. The first agitator 75A is configured to be rotatable by receiving a driving force from the developing coupling 710 via an idle gear 715A and a first agitator gear 713. The second agitator 75B includes a stirring rod 78B and a stirring sheet 79B. The second agitator 75B is configured to be rotatable by receiving a driving force from the first agitator gear 713 via idle gears 715B and 715C and a second agitator gear 714.

[0029] The second agitator 75B supplies the toner in the toner storage portion 74 to the first agitator 75A side. The toner near the first agitator 75A in the toner storage portion 74 is stirred by the first agitator 75A and then supplied to the supply roller 72 side, and further supplied to the developing roller 71 by the supply roller 72.

[0030] <Configuration of the photosensitive unit> Next, the detailed configuration of the photoreceptor unit 6 will be described. FIG. 8 is a perspective view of the process cartridge 5. FIG. 9 is a partial perspective view of the photoreceptor unit 6. FIG. 10 is a perspective view of the developing unit 7 and the photoreceptor unit 6. FIG. 11 is a perspective view of the process cartridge 5. FIG. 12 is a top view showing the left-right arrangement relationship of the photoreceptor unit 6, the developing unit 7, the developing roller 71, and the end seal 717. In FIG. 12, for the sake of explanation, the developing roller 71 and the end seal 717 are shown in a state where they are taken out from the developing unit 7 without changing their left-right positions.

[0031] As shown in FIG. 8, the photoreceptor unit 6 mainly includes a frame 610 having a pair of left side walls 611 and right side walls 612, and a photoreceptor drum 61 rotatably supported behind the frame 610. In front of the frame 610, there are a mounting portion 615 where the developing unit 7 can be mounted, a gripping portion 617 for the user to grip the photoreceptor unit 6, a pressing member 640 for pressing the developing unit 7, and a lift member (moving member) 642 for lifting the developing unit 7. The lift member 642 lifts the developing unit 7 mounted on the mounting portion 615. The toner storage portion 74 of the developing unit 7 mounted on the mounting portion 615 is arranged between the left side wall 611 and the right side wall 612 in the left-right direction.

[0032] The life of the developing unit 7 determined by the amount of toner stored in the developing unit 7 is set shorter than the life of the photoreceptor unit 6 determined by the thickness of the photosensitive layer of the photoreceptor drum 61. Therefore, it is necessary to replace only the developing unit 7 that has reached the end of its life separately from the photoreceptor unit 6. In that case, open the door 21, take out the process cartridge 5 from the apparatus main body 2, remove the developing unit 7 that has reached the end of its life from the photoreceptor unit 6, and attach another developing unit 7 to the photoreceptor unit 6 as shown in the mounting direction AD in FIG. 10. Then, mount the photoreceptor unit 6 with the developing unit 7 mounted thereon as the process cartridge 5 into the apparatus main body 2.

[0033] As shown in FIGS. 8, 10, and 11, on the left side wall 611 and the right side wall 612 of the frame 610, receiving portions 641 for receiving the rotation bearing members 746A and 746B of the developing roller 71 are formed in front of the photosensitive drum 61. The receiving portion 641 is a substantially U-shaped recess with the front side open when viewed from the left side. During the process of mounting the developing unit 7 onto the photoreceptor unit 6, the rotation shaft 746 of the developing roller 71 is inserted therein. The receiving portion 641 guides the movement of the developing unit 7 in the mounting direction AD shown in FIG. 10.

[0034] As shown in FIG. 12, the pressing member 640 is provided at both ends in the left-right direction in front of the frame 610 and is biased in the front-to-back direction by a compression spring 640A as a biasing member. Therefore, due to the biasing force of the compression spring 640A, the pressing member 640 presses the pressed ribs 716A and 716B provided on the first housing portions 700A and 700B of the housing 700 of the developing unit 7, respectively. By pressing the developing unit 7 with the pressing member 640, the developing roller 71 is biased toward the photosensitive drum 61.

[0035] Also, as shown in FIG. 9, a helical photoreceptor gear (first gear) 65 and a helical transfer gear (second gear) 66 are fixed to the left end portion of the photosensitive drum 61 and are configured to rotate integrally with the photosensitive drum 61. When the process cartridge 5 is mounted on the apparatus main body 2, a driving gear (not shown) of the apparatus main body 2 meshes with the photoreceptor gear 65, so that a driving force is transmitted to the photosensitive drum 61 and the transfer gear 66 to make them rotatable. Further, the transfer gear 66 meshes with a transfer roller gear (third gear) 67 fixed to the left end portion of the transfer roller 63, and the transfer roller 63 is also in a rotatable state.

[0036] When the driving force is transmitted, the photosensitive drum 61 receives a force to be pressed to the right by the action of the helical teeth of the photoreceptor gear 65. Also, the direction in which the helical teeth of the transfer gear 66 incline is set to be opposite to the direction in which the helical teeth of the photoreceptor gear 65 incline, and the direction in which the helical teeth of the transfer roller gear 67 incline is set to be the same as the direction in which the helical teeth of the photoreceptor gear 65 incline. Therefore, the transfer roller 63 receives a force to be pressed to the right by the action of the helical teeth of the transfer roller gear 67. By adopting such a configuration, the transfer roller 63 is biased in the same direction (right side) as the photosensitive drum 61. As a result, with respect to the rotational axis direction of the photosensitive drum 61, the photosensitive drum 61 and the transfer roller 63 can be positioned by abutting against the right side wall 612 of the frame 610 respectively, so that the positional accuracy between the transfer roller 63 and the photosensitive drum 61 can be improved. As a result, the tolerances that need to be noted in the design can be reduced, so that the transfer roller 63 etc. can be miniaturized and the cost can be reduced. Also, since the transfer roller gear 67 has helical teeth, when the transfer roller 63 is rotating, the position of the transfer roller 63 in the rotational axis direction (left - right direction) is stable, so that image defects are less likely to occur.

[0037] Also, the outer diameter of the transfer gear 66 is set to be smaller than the outer diameter of the photoreceptor gear 65. Thereby, the photoreceptor gear 65 can be surely meshed with the drive gear of the apparatus main body 2. Note that, with respect to the rotational axis direction of the photosensitive drum 61, the direction in which the photosensitive drum 61 and the transfer roller 63 are respectively biased by the biasing force of the helical gear may be the left side instead of the right side.

[0038] Also, as shown in FIG. 8, in a state where the developing unit 7 is attached to the photoreceptor unit 6, the gripping portion 617 of the photoreceptor unit 6 is disposed on the front side of the gripping portion 701 of the developing unit 7. And, the length of the gripping portion 617 in the left-right direction is configured to be larger than the length of the gripping portion 701 in the left-right direction. Here, the photoreceptor unit 6 with the developing unit 7 attached is heavier than the developing unit 7 alone. Thus, with such a relationship of the lengths in the left-right direction, when the user grips the photoreceptor unit 6 with the heavier developing unit 7 attached, the user can grip the gripping portion 617 in a more stable way than when gripping the gripping portion 701. Therefore, the usability of the user in handling the process cartridge 5 can be improved.

[0039] <Position relationship between each bias contact and the developing coupling 710> FIG. 20 is a view of a part of the developing unit 7 installed on a horizontal plane as seen from the right side in the rotation axis direction of the developing roller 71. The developing unit 7 is provided with a first electrical contact 720A that is electrically connected to the developing roller 71 and to which a voltage applied to the developing roller 71 is supplied, and a second contact 720B that is electrically connected to the supply roller 72 and to which a voltage applied to the supply roller 72 is supplied. By these electrical contacts coming into contact with power supply contacts (not shown) provided on the apparatus main body 2, power is supplied to the developing roller 71 and the supply roller 72.

[0040] In FIG. 20, in order to explain the positional relationship between the developing coupling (driving force receiving member) 710 and the first electrical contact 720A and the second electrical contact 720B in the vertical direction and the front-rear direction, the driving force receiving portion of the developing coupling 710 and the rotation center 710E are marked with a dashed line. As shown in FIG. 20, in the front-rear direction (horizontal direction), the rotation center 710E is disposed within the region of the width W1 where the first contact 720A and the second contact 720B are disposed. Also, in the vertical direction (vertical direction), the rotation center 710E is disposed within the region of the width W2 where the first electrical contact 720A and the second electrical contact 720B are disposed. The width W1 is the distance between the most front end and the most rear end in the front-rear direction among the first electrical contact 720A and the second electrical contact 720B. The width W2 is the distance between the most upper end and the most lower end in the vertical direction among the first electrical contact 720A and the second electrical contact 720B. The region where the first electrical contact 720A and the second electrical contact 720B are disposed in the front-rear direction and the vertical direction is a region within the width W1 in the front-rear direction and within the width W2 in the vertical direction. By doing so, the developing coupling 710 that needs to contact the apparatus main body 2, the first electrical contact 720A, and the second electrical contact 720B can be disposed at almost the same position in the vertical direction and the front-rear direction. Therefore, it is possible to suppress the increase in the size of the developing unit 7 in the vertical direction and the front-rear direction.

[0041] Note that the voltage applied to the developing blade that regulates the thickness of the toner carried on the developing roller 71 may be supplied from the second electrical contact 720B.

[0042] <Pressing Configuration of Developing Unit 7> Next, the pressed ribs 716A and 716B, which are the pressed portions of the developing unit 7, will be described with reference to FIGS. 6, 15, and 19. FIG. 15 is a perspective view of the photosensitive unit 6 with the developing unit 7 mounted thereon. FIG. 19 is a side view of the developing unit 7 as viewed from the left side. As shown in FIG. 6, near the left side wall 704 and the right side wall 705 of the housing 700, the pressed ribs 716A and 716B are provided at both ends in the left-right direction, which is a portion having relatively high strength in the front-rear direction. Thereby, it is possible to ensure the strength of the housing 700 and suppress deformation due to the pressing force of the pressing member 640.

[0043] Also, the portions of the pressed ribs 716A and 716B that come into contact with and are pressed by the pressing member 640 are defined as the pressed portions 716A1 (first pressed portion) and 716B1 (second pressed portion), and the contact portion where the developing roller 71 contacts the photosensitive drum 62 is defined as the contact portion 71b. With respect to the pressing direction of the pressing member 640, in order for the developing roller 71 to be stably pressed against the photosensitive drum 61, it is better for the pressed portions 716A1 and 716B1 to be as far away from the contact portion 71b as possible. That is, the farther the pressed portions 716A1 and 716B1 are from the contact portion 71b, the larger the volume of the housing 700 existing between the pressed ribs 716A and 716B and the bearing portion of the developing roller 71. For this reason, it is less susceptible to variations in the biasing force of the two compression springs 640A, and it is less likely for a difference in the force biasing the developing roller 71 against the photosensitive drum 61 to occur between the left and right. Here, the pressing direction of the pressing member 640 is parallel to the front-rear direction.

[0044] Therefore, the pressed ribs 716A and 716B are provided on the front side of the stirring rods 78A and 78B of the first agitator 75A and the second agitator 75B with respect to the pressing direction of the pressing member 640. Specifically, the rotation center 78B1 of the stirring rod 78B of the second agitator 75B is arranged at a position farther from the rotation center of the developing roller 71 than the rotation center 78A1 of the stirring rod 78A of the first agitator 75A. And in the front-rear direction, the distance from the contact portion 71b to the pressed portion 716A1 is longer than the distance from the contact portion 71b to the rotation center 78B1 of the stirring rod 78B of the second agitator 75B. Similarly, the distance from the contact portion 71b to the pressed portion 716B1 (see FIG. 6) is longer than the distance from the contact portion 71b to the rotation center 78B1 of the stirring rod 78B of the second agitator 75B. Note that the same relationship also holds for the distances from the rotation center of the developing roller 71 to the rotation center 78B1 and the pressed portion 716B1.

[0045] Furthermore, as shown in FIG. 6, the pressed ribs 716A and 716B are arranged offset in the front-rear direction parallel to the pressing direction of the pressing member 640. Specifically, the pressed rib 716B is arranged on the rear side of 716A. As shown in FIG. 19, with respect to the pressing direction of the pressing member 640 (the direction of the force F1), let the distance from the contact portion 71b of the developing roller 71 with the photosensitive drum 61 to the pressed portion (first pressed portion) 716A1 of the pressed rib 716A be D4. Also, let the distance from the contact portion 71b to the pressed portion (second pressed portion) 716B1 of the pressed rib 716B be D5. Then, the distance D4 is longer than the distance D5. Although the pressed portion 716B1 is not visible when originally viewing the developing unit 7 from the left side, the position of the pressed portion 716B1 is shown in FIG. 19 for the sake of explanation. Also, the pressed portion 716A1 and the pressed portion 716B1 receive the force F1 parallel to each other from the pressing member 640.

[0046] Depending on the positional relationship of the bearings of the developing roller 71 in the housing 700 and the like, the developing roller may rub against one side. Rubbing against one side means the case where the contact pressure against the photosensitive drum 61 is different between the left side portion and the right side portion of the developing roller 71.

[0047] By shifting the positions of the pressed portions 716A1 and 716B1 in the pressing direction (the direction from front to back) of the pressing member 640 in this way, it becomes possible to suppress the occurrence of the above-described rubbing against one side. In order to suppress rubbing against one side, it is also effective to make the spring pressure of the compression spring 640A pressing the left pressing member 640 different from the spring pressure of the compression spring 640A pressing the right pressing member 640. However, with the configuration of shifting the positions of the pressed portions 716A1 and 716B1 in the front-rear direction as described above, the distances from the contact portion 71b can be made different, and it becomes possible to use the same compression spring 640A while suppressing rubbing against one side. Therefore, while stabilizing the left and right contact states between the developing roller 71 and the photosensitive drum 61, cost reduction can be achieved. Depending on the situation of rubbing against one side, the relationship between the distances of the pressed portions 716A1 and 716B1 and the contact portion 71b may be reversed with respect to the pressing direction of the pressing member 640.

[0048] Furthermore, as shown in FIG. 15, the pressed ribs 716A and 716B are displaced and arranged in a removal direction Y1 that is orthogonal to the pressing direction of the pressing member 640 (the direction of the force F1) and the axial direction of the developing roller 71 (the left-right direction). The removal direction Y1 is the direction in which the pressed portions 716A1 and 716B1 of the developing unit 7 move when the developing unit 7 starts to be removed from the photoreceptor unit 6. The removal direction Y1 coincides with the direction of the force received by the supported portions 718A and 746A1 of the developing unit 7 that are supported by the photoreceptor unit 6 when they are supported by the photoreceptor unit 6. In the process of removing the developing unit 7 from the photoreceptor unit 6, the movement trajectories of the pressed portions 716A1 and 716B1 are in an arc shape centered on the rotation center of the developing roller 71 as shown by the separation direction LD.

[0049] Specifically, the pressed rib 716A is disposed above the 716B. As a result, the pressed portion 716A1 is disposed above the pressed portion 716B1. That is, the pressed portion 716A1 is disposed downstream in the removal direction Y1 from the pressed portion 716B1. In other words, as shown in FIG. 19, with respect to the removal direction Y1, the distance D6 between the pressed portion 716A1 and the contact portion 71b is longer than the distance D7 between the pressed portion 716B1 and the contact portion 71b. The front-rear direction and the direction of the force F1 are parallel to the horizontal line when the photoreceptor unit 6 with the developing unit 7 mounted thereon is placed on a horizontal surface, and the up-down direction is parallel to the vertical direction. Also, the position above the pressed portion 716B1 in the up-down direction is the upper position in the vertical direction when the photoreceptor unit 6 with the developing unit 7 mounted thereon is placed on a horizontal surface.

[0050] This will be described with reference to FIG. 19. When considering the moment about the contact portion 71b where the developing roller 71 contacts the photosensitive drum 61, the forces F1 received by the pressed portions 716A1 and 716B1 from the pressing member 640 act as a moment M1. The moment M1 becomes larger as the positions of the pressed portions 716A1 and 716B1 are arranged more downstream than the contact portion 71b with respect to the removal direction Y1.

[0051] Here, on the left side of the developing unit 7, a plurality of gears are arranged, such as a developing roller gear 711, a supply roller gear 712, a first agitator gear 713, a second agitator gear 714, and idler gears 715A, 715B, 715C. There are no gears arranged on the right side of the developing unit 7. Therefore, compared with the right side of the developing unit 7, the weight of the left side becomes heavier. The left side and the right side of the developing unit 7 respectively refer to the portion on one end side and the portion on the other end side of the developing unit 7 with respect to the center of the developing unit 7 in the axial direction of the developing roller 71. Here, by arranging the pressed portion 716A1 on the left side of the developing unit 7 at a position downstream with respect to the pressed portion 716B1 on the right side in the removal direction Y1, a larger moment M1 is generated compared with the right side of the left side of the developing unit 7. As a result, when removing the developing unit 7 from the frame 610, a moment for lifting the heavier left side of the developing unit 7 acts, so that the developing unit 7 is suppressed from tilting in the left - right direction, and the usability is good.

[0052] Also, in this embodiment, a contact surface (force receiving portion) 751A (see FIG. 7) that receives a force in the Y1 direction from the lift member 642 of the photoreceptor unit 6 is only on the right side of the developing unit 7. For this reason, the left side of the developing unit 7 is more difficult to be lifted compared with the right side, and is also more likely to tilt in the left - right direction. Therefore, by adopting a configuration in which a larger moment M1 is generated compared with the right side of the left side of the developing unit 7 as described above, the developing unit 7 is suppressed from tilting in the left - right direction, and the usability is good.

[0053] Also, depending on the weight balance on the left and right sides of the developing unit 7 and the position of the lift member 642, the positional relationship between the pressed portions 716A1 and 716B1 in the vertical direction may be reversed from the above. The developing coupling 710 engages with a developing drive transmission member provided on the apparatus main body 2 and receives a rotational driving force. When the developing coupling 710 receives a rotational driving force, a moment in the opposite direction of the moment M1 is received on the left side of the developing unit 7 with the contact portion 71b as the center. For this reason, since a force acts to cancel out the moment M1 acting on the left side of the developing unit 7 described above, the developing unit 7 can be stably fixed to the frame 610.

[0054] <Configuration of the developing coupling 710> As shown in FIG. 19, the developing coupling 710 is provided with driving force receiving portions 710A to 710D that receive a driving force from a developing drive transmission member. The driving force receiving portions 710A to 710D are arranged symmetrically with respect to the center of the developing coupling 710. By doing so, the loss of the driving force can be reduced. The driving force receiving portions 710A to 710D are composed of four surfaces, and at least three of them are used to transmit the driving force. Inlets of the driving force receiving portions 710A to 710D are each provided with an inclined surface for guiding the developing drive transmission member in order to engage with the developing drive transmission member provided on the apparatus main body 2.

[0055] <Support configuration of the developing unit 7> Next, the support structure of the developing unit 7 will be described with reference to FIG. 12. In the left-right direction, the pressing portion P of the pressing member 640 is disposed inside the region where the toner on the developing roller 71 is coated. In the left-right direction, the width of the region for coating the toner on the developing roller 71 is determined by the inner end portion 717A of the end seal 717 that contacts the developing roller of the housing 700 and restricts the leakage of toner in the left-right direction from inside the housing 700. Dashed lines extending in the front-rear direction passing through the two pressing portions P that press the pressed portions 716A1 and 716B1 of the pressing member 640 are defined as dashed lines X1a and X1b, respectively, and dashed lines extending in the front-rear direction passing through the position of the inner end portion 717A of the end seal 717 are defined as dashed lines X2a and X2b, respectively. Note that the dashed lines X1a and X1b also pass through the pressed portions 716A1 and 716B1. Then, in the left-right direction, the dashed line X1a is disposed inside the dashed line X2a, and the dashed line X1b is disposed inside the dashed line X2b.

[0056] The biasing force of this compression spring 640A is set so that when the operation portion 642A of the lift member 642 is operated, the developing unit 7 can be moved in a direction away from the photosensitive unit 6.

[0057] As shown in FIG. 12, protrusions 643 protruding upward are provided at both ends in the left-right direction of the bottom surface 613 of the frame 610. The protrusions 643 support the housing 700 by contacting ribs 718 provided at the bottom of the housing 700 of the developing unit 7 shown in FIG. 13. When dashed lines extending in the front-rear direction passing through the centers of the protrusions 643 are defined as dashed lines X3a and X3b, in the left-right direction, the dashed line X3a is disposed outside the dashed line X1a, and the dashed line X3b is disposed outside the dashed line X1b. Note that the outer and inner sides are based on the center of the frame 610 in the left-right direction. By doing so, the distance D3 between the dashed lines X3a and X3b, which is the distance between the support points of the housing 700 by the frame 610 in the left-right direction, can be made larger than the distance D1 between the dashed lines X1a and X1b, and the developing unit 7 can be stably supported.

[0058] If the distance D3 is greater than the distance D1, the broken line X3a may be arranged inside the broken line X1a, or the broken line X3b may be arranged inside the broken line X1b.

[0059] <Lift mechanism of developing unit 7> FIG. 14 is a partial perspective view of the developing unit 7 and the lift member 642. FIG. 16 is a top view of the photosensitive member unit 6 with the developing unit 7 mounted thereon. In (a), the lift member 642 is shown in transparency, and in (b), the lift member 642 is not shown in transparency. FIG. 17 is a cross-sectional view of the photosensitive member unit 6 and the developing unit 7, and the cross-section is parallel to the vertical direction and the front-rear direction. FIG. 17(a) shows a state where the developing unit 7 is mounted on the photosensitive member unit 6, and FIG. 17(b) shows a state where the developing unit 7 is placed on the photosensitive member unit 6.

[0060] The developing unit 7 mounted on the photosensitive member unit 6 is removed from the photosensitive member unit 6 after being shifted to the lifted state by the lift mechanism. This lift mechanism will be described in detail below.

[0061] As shown in FIG. 14, the lift member 642 is rotatably supported by the right side wall 612 while receiving the force of the compression spring 650. The rotation axis 642X of the lift member 642 is parallel to the left-right direction (the axial direction of the photosensitive drum 61). The lift member 642 is biased to rotate in the R1 direction by the force of the compression spring 650. The frame 610 is provided with a notch 614 as shown in FIG. 15 so that the rotation locus of the lift member 642 can be secured.

[0062] When the user presses the operation portion 642A of the lift member 642 against the force of the compression spring 650 to rotate the lift member 642 in the R2 direction, the lift member 642 presses the protruding portion 751, and the developing unit 7 is moved in the detachment direction LD away from the photosensitive member unit 6. As a result, the developing unit 7 can be removed from the photosensitive member unit 6. The operation portion 642A is arranged on the right end side (one end side) of the photosensitive member unit 6.

[0063] The developing unit 7 has a horizontally long and vertically thin configuration with more toner. Therefore, when the user operates the operation part 642A of the lift member 642, it is important that the developing unit 7 can be detached from the photoreceptor unit 6 without feeling more load.

[0064] As one of the devices for reducing the load, it is easier for the user to operate when the area of the operation part 642A is larger. Therefore, as shown in FIGS. 16(a) and 16(b), in the direction of the rotation axis of the lift member 642, the outermost end 642B, which is the outermost end of the operation part 642A, is arranged outside (to the right) of the right side wall 612 arranged on the right end side of the photoreceptor unit 6. Further, in the direction of the rotation axis of the operation part 642A, the outermost end 642B is arranged outside (to the right) of the outermost surfaces of the first contact point 720A and the second contact point 720B. Here, the outside and the inside are based on the center of the frame 610 in the left-right direction. Thereby, the area of the operation part 642A of the lift member 642 can be increased while suppressing an increase in the left-right width of the rear part, which is the front end side (downstream side) in the insertion direction S1 of the process cartridge 5.

[0065] Also, when the process cartridge 5 is placed on a horizontal surface, at least a part of the operation part 642A of the lift member 642 is arranged so as to overlap the pressing member 640 when viewed from above. In this configuration, "when viewed from above" is synonymous with "when viewed from a direction orthogonal to the insertion direction S1 and the left-right direction of the process cartridge 5". In other words, the operation part 642A is arranged at a position where it overlaps the pressing member 640 when the operation part 642A and the pressing member 640 are projected onto the horizontal plane in a state where the photoreceptor unit 6 is placed on the horizontal plane. By adopting such a configuration, it is possible to increase the area of the operation part 642A while suppressing an increase in the occupied area when the process cartridge 5 is viewed from above. And by ensuring a large area of the operation part 642A, the user can easily operate the lift member 642.

[0066] As shown in FIG. 17(a), in the mounted state where the developing unit 7 is mounted on the photoreceptor unit 6, the housing 700 is pressed by the pressing member 640, so that the developing roller 71 is pressed toward the photosensitive drum 61. Further, the developing unit 7 is locked by the pressing member 640 so as not to be detached from the photoreceptor unit 6.

[0067] As shown in FIGS. 14 and 15, one end of the lift member 642 moves the contact surface (contact portion) 751A of the protruding portion 751 of the housing 700 upward. As a result, the developing unit 7 can be moved in the detachment direction LD from the mounting position mounted on the mounting portion 615 (see FIG. 10) and detached from the photoreceptor unit 6.

[0068] As shown in FIG. 17(b), when detaching, the developing unit 7 is held at a temporary support position where the supported surface 700c of the housing 700 is supported by the holding portion 640B of the pressing member 640. Further, the developing unit 7 in the temporary support position is in a state where the rotation shaft 746B (746A) of the developing roller 71 is supported by the receiving portion 641. This state is a lifted state (lift-up state) while the lock (restriction on removing the developing unit 7 from the photoreceptor unit 6) is released. Therefore, the gripping portion 701 of the developing unit 7 is disposed above the mounted state shown in FIG. 17(a). As a result, it is easier for the user to grip the gripping portion 701. Further, if the gripping portion 701 is gripped from the lift-up state and the developing unit 7 is lifted as it is, the developing unit 7 can be removed from the photoreceptor unit 6 without moving other members. In this way, the user can remove the developing unit 7 from the photoreceptor unit 6 and mount a new developing unit 7 on the photoreceptor unit 6.

[0069] FIG. 18 is a view seen from the right side in a state where the photoreceptor unit 6 with the developing unit 7 mounted thereon is placed on a horizontal surface. For the sake of explanation, the description of the right side wall 612 of the photoreceptor unit 6 is omitted.

[0070] As shown in FIG. 18, with the developing unit 7 mounted, the center of rotation of the rotation axis 642B of the lift member 642 is defined as center C1, and the center of the protruding portion 751, that is, the center of rotation of the second agitator 75B is defined as center C2. Further, the center of the protruding portion 752, that is, the center of rotation of the first agitator 75A is defined as center C3, and the center of the shaft portion 71A of the developing roller 71 (the center of rotation of the developing roller 71) is defined as center C4. Also, the straight line connecting center C2 and center C4 is designated as Y1, and the straight line connecting center C3 and center C4 is designated as Y2.

[0071] With the photosensitive unit 6 with the developing unit 7 mounted placed on a horizontal surface, the higher center C1 is installed upward, the operation portion 642A can be arranged upward, and it is easier for the user to operate. Therefore, with the photosensitive unit 6 with the developing unit 7 mounted placed on a horizontal surface, center C1 is configured to be arranged above center C2, center C3, straight line Y1, and straight line Y2 in the vertical direction. With such a configuration, while suppressing the height of the photosensitive unit 6 and the developing unit 7, the operation portion 642A can be arranged at a high position to ensure ease of operation by the user.

[0072] Also, in order to operate the operation portion 642A with a light force to detach the developing unit 7, it is desirable that the contact surface 751A that contacts the lift member 642 of the housing 700 be provided at a position as far as possible from the center C4 of the shaft portion 71A of the developing roller 71. For this reason, the contact surface 751A is provided at a position farther from center C4 than center C3. That is, when viewed from the axial direction of the photosensitive drum 61, under the condition that the distance from center C4 to center C3 is shorter than the distance from center C4 to center C2, the distance from center C4 to the contact surface 751A is longer than the distance from center C4 to center C3, which is farther from center C4.

[0073] FIG. 7 is a perspective view showing the developing unit 7 and the lift member 642 mounted on the photosensitive unit 6. For the purpose of explanation, the developing unit 7 is shown in a state of being cut along a cross section passing through the rotation axis of the second agitator 75B.

[0074] As shown in FIG. 7, the protruding portion 751 pressed by the lift member 642 protrudes rightward (in the axial direction of the developing roller 71) from the right side wall 705 of the housing 700. The protruding portion 751 has a cylindrical shape with a closed right end, and an abutting surface 751A that abuts against and is pressed by one end of the lift member 642 is provided on its outer peripheral surface. That is, the abutting surface 751A has an arc surface shape. The inner peripheral surface of the protruding portion 751 is a bearing portion 751B that rotatably supports the stirring rod 78B as the rotation axis of the second agitator 75B. That is, the bearing portion 751B has an arc surface shape. Note that the bearing portion 751B, which is the inner peripheral surface of the protruding portion 751, may not be the bearing of the stirring rod 78B, but may be the bearing of a rotating member such as the stirring rod 78A, the rotation axis of the supply roller 72, or the rotation axis of the developing roller 71.

[0075] With this configuration, rather than forming the protruding portion for providing the abutting surface 751A and the protruding portion for providing the bearing portion 751B as separate protruding portions protruding from the right side wall 705, the space on the right side of the right side wall 705 of the housing 700 can be made available. Therefore, the degree of freedom in the design of the housing 700 and the photosensitive unit 6 can be increased, or miniaturization can be achieved. Note that the inner peripheral surface and the outer peripheral surface of the protruding portion 751 do not necessarily have to be arc (cylindrical) surface shapes as described above. That is, the inner peripheral surface and the outer peripheral surface of the protruding portion 751 may be formed as flat surfaces, and the abutting surface 751A and the bearing portion 751B may be provided thereon.

[0076] <Modification Example 1> FIG. 21 is a view of the photoreceptor unit 6 with the developing unit 7 of Modification 1 attached, as seen from the right side. As shown in FIG. 21, a cylindrical first protrusion 7511 whose inner peripheral surface is a bearing portion 751B, a second protrusion 7512 having a contact surface 751A provided on its outer peripheral surface, and an intermediate portion 7513 connecting the first protrusion 7511 and the second protrusion 7512 may be provided. The first protrusion 7511, the second protrusion 7512, and the intermediate portion 7513 are all provided so as to protrude rightward (in the axial direction of the developing roller 71) from the right side wall 705 of the housing 700. With this configuration, compared to a configuration in which the protrusion for providing the contact surface 751A and the protrusion for providing the bearing portion 751B are formed as separate protrusions protruding from the right side wall 705, the strength of the two protrusions (the first protrusion 7511 and the second protrusion 7512) can be increased.

[0077] <Modification 2> Next, the photoreceptor unit 206 of Modification 2 will be described. FIG. 22 is a view of the photoreceptor unit 206 of Modification 2 with the developing unit 7 attached, as seen from the right side in a state where it is placed on a horizontal surface. For the sake of explanation, the description of the right side wall of the photoreceptor unit 206 is omitted.

[0078] The photoreceptor unit 206 of Modification 2 is different from the above-described photoreceptor unit 6 in that it includes a corona charger 262 instead of the charging roller 62 and further includes a pre-exposure unit 201 and a recovery roller 202. The other configurations of the photoreceptor unit 206 of Modification 2 are the same as those of the above-described photoreceptor unit 6, and the description thereof is omitted.

[0079] The corona charger 262 is a charging unit that charges the surface of the photosensitive drum 61 non-contactingly. The front exposure unit 201 includes a light-emitting diode as a light source and a light guide as a light guiding member, guides the light emitted from the light-emitting diode with the light guide, and irradiates the surface of the photosensitive drum 61 with light. The current supplied to the light-emitting diode is supplied from the apparatus main body 2. The surface of the photosensitive drum 61 is discharged by the irradiation of light from the front exposure unit 201. Also, a predetermined voltage is applied to the recovery roller 202 from the apparatus main body 2 to recover foreign matters such as paper powder and dust and toner attached to the surface of the photosensitive drum 61. With respect to the rotation direction (arrow 61a) of the photosensitive drum 61 during image formation, they are arranged in order from upstream to downstream as the transfer roller 63, the front exposure unit 201, the recovery roller 202, the corotron charger, and the developing roller 71.

Explanation of Signs

[0080] 1 Image forming apparatus 2 Apparatus main body 5 Process cartridge 6 Photoconductor unit 7 Developing unit 61 Photosensitive drum 63 Transfer roller 71 Developing roller 610 Frame 700 Housing 640 Pressing member 642 Lifting member

Claims

1. A process cartridge, a drum unit including a photosensitive drum rotatable around a rotation axis extending in an axial direction, a drum frame supporting the photosensitive drum, a pressing member, and a lever rotatable relative to the drum frame; a developing unit detachably attached to the drum frame, the developing unit having a developing roller and a developing frame supporting the developing roller, the developing unit being attached to the drum frame such that the developing roller is pressed against the photosensitive drum by the pressing member pressing the developing frame; Equipped with the lever is configured to be able to come into contact with the developing unit when the developing unit is attached to the drum frame, When the drum unit is placed on a horizontal surface with the developing unit attached to the drum frame, the lever and the pressing member at least partially overlap each other when viewed in the vertical direction, the developing frame includes a side wall extending in a direction intersecting a rotational axis direction of the developing roller, a protruding portion protruding from the side wall in the rotational axis direction, and a pressed portion pressed by the pressing member, the pressed portion being provided at a position spaced from the protruding portion, a process cartridge comprising: a lever capable of abutting against the protruding portion;

2. 2. The process cartridge according to claim 1, wherein the lever is configured to be capable of moving the developing unit in a direction in which the developing unit is removed from the drum frame when the developing unit is attached to the drum frame.

3. 3. A process cartridge according to claim 1, wherein said lever protrudes outward from an end of said drum frame in the axial direction.

4. the developing unit includes a developing contact electrically connected to the developing roller; 4. A process cartridge according to claim 1, wherein said lever protrudes outward from an end of said developing contact in the axial direction.

5. the developing unit includes a supply roller in contact with the developing roller, and a supply contact electrically connected to the supply roller; 5. A process cartridge according to claim 1, wherein said lever protrudes outward from an end of said supply contact in the axial direction.

6. the developing frame has a pressed portion that is pressed by the pressing member, 6. A process cartridge according to claim 1, wherein an end of said lever is farther from said rotation axis than said pressed portion in a direction perpendicular to said axial direction.

7. 7. A process cartridge according to claim 1, wherein the lever includes an operating portion having a surface on which projections and recesses are formed.

8. 8. A process cartridge according to claim 7, wherein said surface is a curved surface.

9. 9. The process cartridge according to claim 1, wherein the drum unit includes a charging member that is in contact with the photosensitive drum.

Images