Image forming apparatus, drum unit, and drum assembly including drum unit

Abstract

A drum unit includes: a photosensitive drum rotatable about a drum axis extending in a first direction; a frame including a first side plate and a second side plate, the first side plate being located at a first end of the frame in the first direction, the second side plate being spaced apart from the first side plate in the first direction, the frame rotatably supporting the photosensitive drum between the first side plate and the second side plate in the first direction; and a locking lever pivotable between a locked position and a released position about a pivot axis extending in a second direction intersecting the first direction, wherein in the locked position a developer cartridge held by the frame is locked to the frame, and in the released position the developer cartridge is unlocked from the frame.

Description

[0001] This application is a divisional application of the following patent application:

[0002] Application Number: 201910243282.0

[0003] Application date: March 28, 2019

[0004] Invention Title: Drum Unit and Drum Assembly Including Drum Unit

[0005] Cross-reference to related applications

[0006] This application claims priority to Japanese Patent Application No. 2018-067899, filed on March 30, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0007] This disclosure relates to a drum unit. Background Technology

[0008] Prior art electrophotographic image forming apparatuses include laser printers and light-emitting diode (LED) printers. The image forming apparatus includes a developer cartridge and a drum unit. The drum unit includes multiple photosensitive drums. Each photosensitive drum is rotatable about a drum axis extending in an axial direction. The developer cartridge can be removed from the drum unit. When the developer cartridge is attached to the drum unit, the developing roller of the developer cartridge contacts the photosensitive drum of the drum unit.

[0009] The drum unit includes a frame for holding multiple developer cartridges and locking levers for locking the developer cartridges held in the frame. Each developer cartridge is attached to a corresponding slot in the frame. Each locking lever is pivotable about a pivot axis extending in the axial direction between a locked position and a released position. When the locking lever is in the locked position, the developer cartridge is locked to the frame. When the locking lever is in the released position, the developer cartridge can be removed from the frame. Summary of the Invention

[0010] To allow each locking lever to pivot about a pivot axis from a locked position to a released position, the image forming apparatus incorporates a gap between each locking lever between the developer cartridges held in the frame. In this configuration, adjacent developer cartridges cannot be arranged close to each other. A technique is needed to reduce the size of the drum unit in the direction in which the photosensitive drum is positioned.

[0011] In response to the above problems, one or more aspects of the present invention are directed to a drum unit comprising adjacent developer cartridges arranged close to each other, and thus reducing the size in the direction in which the photosensitive drum is positioned.

[0012] A first aspect of this disclosure provides a drum unit having the following structure. The drum unit includes a photosensitive drum, a frame, and a locking lever. The photosensitive drum is rotatable about a drum axis extending in a first direction. The frame includes a first side plate located at a first end in the first direction and a second side plate spaced apart from the first side plate in the first direction. The frame rotatably supports the photosensitive drum between the first and second side plates in the first direction. The frame holds a developer cartridge. The locking lever is movable and, in some examples, pivotable about a pivot axis extending in a second direction intersecting the first direction. The locking lever is movable between a locked position, in which the developer cartridge is locked to the frame, and in the released position, the developer cartridge is unlocked from the frame.

[0013] A second aspect of this disclosure provides a drum unit having the following structure. The drum unit includes a photosensitive drum, a frame, and a locking lever. The photosensitive drum is rotatable about a drum axis extending in a first direction. The frame includes a first side plate located at a first end in the first direction of the frame and a second side plate spaced apart from the first side plate in the first direction. The frame rotatably supports the photosensitive drum located between the first and second side plates in the first direction. The locking lever is received in an opening in the first side plate of the frame. The locking lever has a first end and a second end. The second end of the locking lever is positioned relative to the first end. The second end of the locking lever is movable and, in some examples, pivotable about a pivot axis extending in a second direction intersecting the first direction. The locking lever is pivotable between a locked position and a released position, in which at least a portion of the second end of the locking lever is located between the first and second side plates, and in the released position, at least a portion of the second end of the locking lever extends away from the first side plate in the first direction.

[0014] A third aspect of this disclosure provides a drum unit having the following structure. The drum unit includes a plurality of photosensitive drums, a frame, and a plurality of locking levers. Each of the plurality of photosensitive drums is rotatable about a drum axis extending in a first direction. The plurality of photosensitive drums are positioned along a second direction intersecting the first direction. The frame includes a first side plate located at a first end in the first direction of the frame and a second side plate spaced apart from the first side plate in the first direction. The frame rotatably supports the plurality of photosensitive drums located between the first and second side plates in the first direction. The frame holds a plurality of developer cartridges. Each of the plurality of locking levers is movable and, in some examples, is pivotally supported by the frame and spaced apart in the second direction. Each of the plurality of locking levers is movable between a locked position and a released position. Each of the plurality of locking levers is positioned such that, when viewed from the first direction, a first outer surface of the corresponding developer cartridge held by the frame completely overlaps with the locking lever. Attached Figure Description

[0015] Figure 1 This is a conceptual diagram of an image forming device;

[0016] Figure 2 It is a three-dimensional view of the drum unit and developer cartridge;

[0017] Figure 3 It is a 3D view of the developer cartridge;

[0018] Figure 4 From and Figure 3 A three-dimensional view of the developer cartridge viewed from different angles;

[0019] Figure 5 This is a side view of the developer cartridge at one end in the first direction;

[0020] Figure 6 This is a side view of the developer cartridge at the other end in the first direction;

[0021] Figure 7 It is a 3D view of the drum unit;

[0022] Figure 8 This is a side view of the drum unit illustrating the internal structure of the drum unit during the attachment of the developer cartridge to the drum unit;

[0023] Figure 9 This is a side view of the internal structure of the drum unit, where the developer cartridge is attached to the drum unit.

[0024] Figure 10 This is a side view of the developer cartridge during the attachment of the developer cartridge to the drum unit;

[0025] Figure 11 This is a side view of the developer cartridge attached to the drum unit;

[0026] Figure 12 This is a schematic diagram illustrating the forces interacting during the attachment of the developer cartridge to the drum unit;

[0027] Figure 13 This is a perspective view of the drum unit showing the locking lever during the attachment of the developer cartridge to the drum unit;

[0028] Figure 14 This is a three-dimensional view of the drum unit when the developer cartridge is attached to it.

[0029] Figure 15 It is in the release position. Figure 13 An enlarged view of the locking lever shown. Detailed Implementation

[0030] Embodiments of this disclosure will now be described in conjunction with the accompanying drawings.

[0031] The first direction here refers to the direction along the drum axis of the photosensitive drum. The second direction here refers to the direction in which multiple photosensitive drums are mounted. The third direction here refers to the longitudinal direction of each end face of the developer cartridge attached to the drum unit. The first, second, and third directions intersect each other (at right angles in some embodiments).

[0032] 1. Structure of an image forming device

[0033] Figure 1 This is a conceptual diagram of an image forming apparatus 100. The image forming apparatus 100 can be a laser printer or a light-emitting diode (LED) printer. Figure 1 As shown, the image forming apparatus 100 includes a drum unit 3 and a plurality of developer cartridges 1. The drum unit 3 includes a frame configured to hold the developer cartridges 1.

[0034] Figure 2 This is a perspective view of the drum unit 3 and the developer cartridge 1. The developer cartridge 1 can be attached separately to the drum unit 3. The drum unit 3, which holds the developer cartridge 1, is configured to be mounted on the image forming apparatus 100 (see [reference]). Figure 1 The image forming apparatus 100 uses the toner supplied from the developer cartridges 1 to form (output) an image on the recording surface of a printed sheet. Each developer cartridge 1 contains a different color (e.g., cyan, magenta, yellow, or black) of toner. In this embodiment, the drum unit 3 holds four developer cartridges 1. In some embodiments, the drum unit 3 may hold one to three or more developer cartridges 1.

[0035] 2. Structure of the developer cartridge

[0036] Figure 3 and 4 This is a three-dimensional view of developer cartridge 1. Figure 5 and 6 The end face of developer cartridge 1 in a first direction is shown. For example... Figures 3 to 6 As shown, the developer cartridge 1 according to this embodiment includes a housing 11, a developing roller 12, a stirrer (not shown), and a connector 24.

[0037] The housing 11 is a shell configured to contain a toner. The housing 11 has a chamber (not shown) configured to contain the toner. The housing 11 extends in a first direction. The housing 11 has a first outer surface 111 and a second outer surface 112 located away from the first outer surface 111 in the first direction. The first outer surface 111 is one end face (first end face) of the housing 11 in the first direction. The longitudinal direction of the first outer surface 111 corresponds to a third direction. The second outer surface 112 is the other end face (second end face) of the housing 11 in the first direction. The longitudinal direction of the second outer surface 112 corresponds to a third direction. The housing 11 has a first end 113 in the third direction and a second end 114 located away from the first end 113 in the third direction.

[0038] The developing roller 12 is rotatable about a roller axis extending in a first direction. The developing roller 12 is located between the first outer surface 111 and the second outer surface 112 of the housing 11 in the first direction. The developing roller 12 is closer to the first end 113 in the third direction than the second end 114.

[0039] More specifically, the developing roller 12 includes a developing roller body and a developing roller shaft 12c. The developing roller body is cylindrical, and the developing roller shaft 12c is cylindrical. The developing roller shaft 12c extends through the center of the developing roller body. The developing roller shaft 12c rotates together with the developing roller body. The developing roller shaft 12c has two ends in a first direction that are rotatably supported by the two end faces of the housing 11.

[0040] The developing roller 12 (developing roller body) has an exposed surface 12a and a covered surface 12b. The exposed surface 12a is located at one end (first end) of the developing roller 12 in a second direction, which is exposed outside the housing 11. The covered surface 12b is located at the other end (second end) of the developing roller 12 in the second direction, inside the housing 11. When the developer cartridge 1 is attached to the drum unit 3, the outer peripheral surface (exposed surface 12a) of the developing roller 12 contacts the outer peripheral surface of the photosensitive drum 31.

[0041] A stirrer (not shown) is rotatable about a stirrer axis extending in a first direction. The stirrer includes multiple agitator blades. The stirrer is located between a first outer surface 111 and a second outer surface 112 of the housing 11 in the first direction. In the third direction, the stirrer is positioned closer to the second end 114 of the housing 11 than to the developing roller 12. The stirrer rotates to agitate the toner contained in the chamber of the housing 11.

[0042] Figure 3 and 5The connector 24 shown receives a driving force applied by the body of the image forming apparatus 100. The connector 24 is rotatable about a connector axis extending in a first direction. The connector 24 is closer to the second end 114 of the housing 11 in a third direction than the developing roller 12. The connector 24 has a recess 115 in the first direction. When the developer cartridge 1, attached to the drum unit 3, is mounted on the body housing 101 of the image forming apparatus 100, the drive shaft of the body housing 101 of the image forming apparatus 100 is received in the recess 115. Thus, the connector 24 is connected to the drive shaft in a manner that does not rotate relative to each other. Rotation of the drive shaft causes the connector 24 to rotate. Then, rotation of the connector 24 causes the developing roller 12 and the agitator to rotate.

[0043] 3. Structure of the drum unit

[0044] Now we will mainly refer to Figure 7 Describe the structure of drum unit 3. Figure 7 This is a 3D view of drum unit 3.

[0045] According to this embodiment, drum unit 3 is a drum housing. For example... Figures 7 to 9 As shown, the drum unit 3 includes multiple photosensitive drums 31, a first side plate 33, a second side plate 34, and a pull-out plate 35. In this embodiment, the drum unit 3 includes four photosensitive drums 31.

[0046] The photosensitive drum 31 transfers the toner supplied from the developer cartridge 1 to the printing sheet. The photosensitive drums 31 are spaced apart in a second direction. Each photosensitive drum 31 is cylindrical. Each photosensitive drum 31 has an outer peripheral surface. Each photosensitive drum 31 extends in a first direction. The outer peripheral surface of the photosensitive drum 31 is coated with a photosensitive material. Each photosensitive drum 31 is rotatable about a drum rotation axis extending in the first direction.

[0047] The first side plate 33, the second side plate 34, and the pull-out plate 35 together define a frame 38 for holding the photosensitive drum 31. The frame 38 has an opening at one end located in a third direction (in this embodiment, the direction opposite to gravity).

[0048] A first side plate 33 supports a first end of the photosensitive drum 31 in a first direction. The first side plate 33 extends perpendicular to the first direction. The first side plate 33 extends in a second direction. The first side plate 33 is a plate. The first side plate 33 includes a plurality of (four in this embodiment) developer cartridge holders 30. The developer cartridge holders 30 are located on the inner surface of the first side plate 33 in the first direction. The developer cartridge holders 30 are spaced apart in the second direction. The developer cartridge holders 30 of the first side plate 33 receive the first end of the developer cartridge 1 in the first direction (one end at the first outer surface 111).

[0049] The second side plate 34 supports the second end of the photosensitive drum 31 in a first direction. The second side plate 34 extends perpendicular to the first direction. The second side plate 34 extends in a second direction. The second side plate 34 is a plate. The second side plate 34 includes a plurality of (four in this embodiment) developer cartridge holders (not shown). The developer cartridge holders are located on the inner surface of the second side plate 34 in the first direction. The number of developer cartridge holders of the second side plate 34 is equal to the number of developer cartridge holders 30 of the first side plate 33. The developer cartridge holders of the second side plate 34 receive the second end (one end at the second outer surface 112) of the developer cartridge 1 in the first direction.

[0050] The pull-out plate 35 connects to the second end of the first side plate 33 in a second direction and the second end of the second side plate 34 in a second direction. The pull-out plate 35 extends perpendicular to the second direction. The pull-out plate 35 extends in a first direction. The pull-out plate 35 is a plate. The pull-out plate 35 has a handle 36. The handle 36 is located on the outer surface of the pull-out plate 35 in the second direction. The handle 36 is gripped by the user to pull out or push the drum unit 3 into the body housing 101.

[0051] When the developer cartridge 1 is attached to the drum unit 3, the first end of the housing 11 in the first direction is held by the developer cartridge holder 30 of the first side plate 33, and the second end of the housing 11 in the first direction is held by the developer cartridge holder of the second side plate 34. When the developer cartridge 1 is attached to the drum unit 3, the outer peripheral surface (exposed surface 12a) of the developing roller 12 contacts the outer peripheral surface of the photosensitive drum 31.

[0052] The image forming apparatus 100 having the above structure forms an image on a printing sheet in the following manner. As the connector 24 and the photosensitive drum 31 rotate, toner is supplied from the chamber of the housing 11 to the outer peripheral surface of the photosensitive drum 31 via the developing roller 12. Based on the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 31, the toner held on the outer peripheral surface of the developing roller 12 moves from the developing roller 12 to the photosensitive drum 31. Thus, the electrostatic latent image appears on the outer peripheral surface of the photosensitive drum 31. The photosensitive drum 31 then transfers the toner onto the printing sheet.

[0053] 4. Detailed structure for attachment and removal

[0054] Now refer to Figures 3 to 15 The structure according to this embodiment is described for attaching the developer cartridge 1 to and removing it from the drum unit 3. Figure 8 This is a side view of the drum unit 3 illustrating the internal structure of the drum unit 3 during the attachment of a developer cartridge 1 to the drum unit 3. Figure 9 This is a side view of the drum unit 3, in which the developer cartridge 1 is attached to the internal structure of the drum unit 3. Figure 10 This is a side view of the developer cartridge 1 during the period when the developer cartridge 1 is attached to the developer cartridge holder 30 of the drum unit 3. Figure 11 This is a side view of the developer cartridge 1 attached to the developer cartridge holder 30 of the drum unit 3. Figure 12 This is a schematic diagram illustrating the forces interacting during the attachment of the developer cartridge 1 to the developer cartridge holder 30 of the drum unit 3. Figure 13 This is a perspective view of the drum unit 3, showing the locking lever 48 during the attachment of the developer cartridge 1 to the drum unit 3. Figure 14 This is a perspective view of the drum unit 3 with the locking lever 48 shown when the developer cartridge 1 is attached to the drum unit 3. Figure 15 It is in the release position. Figure 13 An enlarged view of the locking lever 48 shown.

[0055] The developer cartridge 1 according to this embodiment includes a first protrusion 13, a first ring 14, a first pressure receiving surface 15, a second protrusion 16, a second ring 17, a first protrusion 18, a third protrusion 19, a second pressure receiving surface 21, a fourth protrusion 22, and a second protrusion 23.

[0056] The first protrusion 13 extends in a first direction. In this embodiment, the first protrusion 13 is a component separate from and fixed to the housing 11. In some embodiments, the first protrusion 13 may be integral with the housing 11. The first protrusion 13 may move together with the housing 11. The first protrusion 13 is located on the first outer surface 111. More specifically, the first protrusion 13 protrudes outward from the first outer surface 111 in a first direction. As described in detail below, the first protrusion 13 bears the weight of the developer cartridge 1. The first protrusion 13 is located away from the developing roller 12 in second and third directions. As described in detail below, when the developer cartridge 1 is attached to the drum unit 3, the first protrusion 13 is supported by the support surface 41 of the drum unit 3 (described later).

[0057] The first ring 14 is cylindrical. The first ring 14 is rotatable about the first protrusion 13. The first ring 14 is hollow. The first ring 14 receives the first protrusion 13. In some embodiments, the first ring 14 may not be cylindrical. For example, the first ring 14 may be polygonal. The developer cartridge 1 may not include the first ring 14. In this case, the outer peripheral surface of the first protrusion 13 can be used as the first ring.

[0058] The first pressure receiving surface 15 has an arcuate surface that curves along an arc along a straight line in a first direction. The first pressure receiving surface 15 is located inside the first outer surface 111 in the first direction. In the second direction, the first pressure receiving surface 15 is located further away from the developing roller 12 than the first protrusion 13.

[0059] The first protrusion 13 is located at a first distance D1 from the developing roller 12 in a third-direction orientation. The first pressure receiving surface 15 is located at a second distance D2 (D2≤D1) from the developing roller 12 in a third-direction orientation, at a distance of either the first distance D1 or less than the first distance D1. In this embodiment, as... Figure 5 and 6 As shown, the distance between the first pressure receiving surface 15 facing upwards and the developing roller 12 is approximately equal to the first distance D1.

[0060] In this embodiment, the first distance D1 can be defined as the distance between the outer surface of the first protrusion 13 and the outer peripheral surface of the developing roller 12, and the second distance D2 can be defined as the distance between the outer surface of the first pressure receiving surface 15 and the outer peripheral surface of the developing roller 12. In some embodiments, these distances may be defined differently. For example, the first distance D1 may be the distance between the rotation center of the first protrusion 13 and the rotation center of the developing roller 12, and the second distance D2 may be the distance between the center of the arc defined by the outer surface of the first pressure receiving surface 15 and the rotation center of the developing roller 12. In other embodiments, the first distance D1 may be the distance between the outer surface of the first protrusion 13 and the outer peripheral surface of the developing roller shaft 12c, and the second distance D2 may be the distance between the outer surface of the first pressure receiving surface 15 and the outer peripheral surface of the developing roller shaft 12c.

[0061] The second protrusion 16 extends in a first direction. In this embodiment, the second protrusion 16 is a component separate from the housing 11 and is fixed to the housing 11. In some embodiments, the second protrusion 16 may be integral with the housing 11. The second protrusion 16 may move together with the housing 11. The second protrusion 16 is located on the first outer surface 111. More specifically, the second protrusion 16 protrudes outward from the first outer surface 111 in a first direction. Compared to the first protrusion 13, the second protrusion 16 is positioned further away from the developing roller 12 in both the second and third directions. In other words, the second protrusion 16 is opposite to the developing roller 12 in the second direction relative to the first protrusion 13. The second protrusion 16 is opposite to the developing roller 12 in the third direction relative to the first protrusion 13. As described in detail below, when the developer cartridge 1 is attached to the drum unit 3, the second protrusion 16 receives a pressing force in the third direction from the second end 114 to the first end 113.

[0062] The second ring 17 is cylindrical and rotatable about the second protrusion 16. The second ring 17 is hollow. The second ring 17 receives the second protrusion 16. In some embodiments, the second ring 17 may not be cylindrical. For example, the second ring 17 may be polygonal. The developer cartridge 1 may not include the second ring 17. In this case, the outer peripheral surface of the second protrusion 16 may be used as the second ring.

[0063] The first protrusion 18 extends in a first direction. The first protrusion 18 is located at a first end of the developing roller 12 in a first direction. More specifically, the first protrusion 18 is located at a first end of the developing roller shaft 12c in a first direction. The first protrusion 18 is a component separate from the developing roller 12 and is attached to the developing roller 12. More specifically, the first protrusion 18 is a component separate from the developing roller shaft 12c and is attached to the developing roller shaft 12c. In some embodiments, the first protrusion 18 may be integral with the developing roller 12. More specifically, the first protrusion 18 may be integral with the developing roller shaft 12c. As described in detail below, when the developer cartridge 1 is attached to the drum unit 3, the first protrusion 18 contacts the guide 49 of the drum unit 3. Thus, the first protrusion 18 positions the developer cartridge 1 on the drum unit 3.

[0064] Figure 4 and 6 The third protrusion 19 shown extends in a first direction. In this embodiment, the third protrusion 19 is a component separate from and fixed to the housing 11. In some embodiments, the third protrusion 19 may be integral with the housing 11. The third protrusion 19 may move together with the housing 11. The third protrusion 19 is located on the second outer surface 112. More specifically, the third protrusion 19 protrudes outward from the second outer surface 112 in a first direction. The third protrusion 19 is located on the axis in the first direction, like the first protrusion 13. The developer cartridge 1 includes a third ring that can rotate about the third protrusion 19. As described in detail below, the third protrusion 19 and the first protrusion 13 together bear the weight of the developer cartridge 1.

[0065] The second pressure receiving surface 21 has an arcuate surface that curves along an arc along a straight line in the first direction. The second pressure receiving surface 21 is located away from the first pressure receiving surface 15 in the first direction. The second pressure receiving surface 21 is located inside the second outer surface 112 in the first direction. When viewed in the first direction, the second pressure receiving surface 21 overlaps with the first pressure receiving surface 15. In other words, the second pressure receiving surface 21 is farther from the developing roller 12 than the third protrusion 19 in the second direction.

[0066] The third protrusion 19 is located at a first distance D1 from the developing roller 12 in the third direction. The second pressure receiving surface 21 is located at a first distance D1 or a second distance D2 (D2≤D1) from the developing roller 12 in the third direction.

[0067] The fourth protrusion 22 extends in a first direction. In this embodiment, the fourth protrusion 22 is a component separate from the housing 11 and is fixed to the housing 11. In some embodiments, the fourth protrusion 22 may be integral with the housing 11. The fourth protrusion 22 can move together with the housing 11. The fourth protrusion 22 is located on the second outer surface 112. More specifically, the fourth protrusion 22 protrudes outward from the second outer surface 112 in a first direction. The fourth protrusion 22 is located on the same axis as the first protrusion 13 extending in the first direction. The developer cartridge 1 has a ring that can rotate about the fourth protrusion 22.

[0068] The second protrusion 23 extends in a first direction. The second protrusion 23 is located at a second end of the developing roller 12 in the first direction. More specifically, the second protrusion 23 is located at a second end of the developing roller shaft 12c in the first direction. The second protrusion 23 is a component separate from the developing roller 12 and is attached to the developing roller 12. More specifically, the second protrusion 23 is a component separate from the developing roller shaft 12c and is attached to the developing roller shaft 12c. In some embodiments, the second protrusion 23 may be integral with the developing roller 12. More specifically, the second protrusion 23 may be integral with the developing roller shaft 12c. The second protrusion 23 is located on the same axis as the first protrusion 18 extending in the first direction. As described in detail below, the second protrusion 23 and the first protrusion 18 together position the developer cartridge 1 on the drum unit 3.

[0069] The image forming apparatus 100 according to this embodiment includes a developer cartridge holder 30 on a first side plate 33 and a developer cartridge holder on a second side plate 34. More specifically, as Figure 8 and 9 As shown, in this embodiment, the developer cartridge holder 30 of the first side panel 33 and the developer cartridge holder of the second side panel 34 each include a support 46, a pressing member 47, a locking lever 48, and a guide 49. The support 46, pressing member 47, locking lever 48, and guide 49 in each developer cartridge holder 30 of the first side panel 33 are paired with these components in the corresponding developer cartridge holder of the second side panel 34. The developer cartridge holder 30 of the first side panel 33 will be described primarily without repeating the description of the developer cartridge holder of the second side panel 34.

[0070] like Figure 10 As shown, the support member 46 has a support surface 41. The support member 46 protrudes from the inner surface of the first side plate 33 in a first direction. In this embodiment, the support surface 41 faces the direction opposite to gravity. The support surface 41 is a flat surface perpendicular to a third direction. When the developer cartridge 1 is attached to the developer cartridge holder 30, the support surface 41 supports the first protrusion 13 via the first ring 14.

[0071] The pressing member 47 has a first pressing surface 42. The pressing member 47 is located on the inner surface of the first side plate 33. The first pressing surface 42 is a plane substantially perpendicular to the second direction. The first pressing surface 42 can slide in the second direction. The pressing member 47 includes a spring (not shown) as an elastic member. When the first pressing surface 42 is not subjected to a pressing force in the second direction, the spring has a second length L2. In other words, the spring has the second length L2 when the developer cartridge 1 has not been attached to the drum unit 3 yet. When the developer cartridge 1 has been attached to the drum unit 3, the first pressing surface 42 presses against the first pressure receiving surface 15 and slides toward the second end of the drum unit in the second direction. This causes the spring to shorten to a first length L1, and the first length L1 is less than the second length L2 (L1 < L2). The spring having the first length L1 presses the first pressing surface 42 toward the first end of the drum unit 3 in the second direction. When the developer cartridge 1 is attached to the developer cartridge holder 30, the first pressing surface 42 contacts the first pressure receiving surface 15 to apply a pressing force to the first pressure receiving surface 15, and this pressing force points from the second end to the first end of the drum unit 3 in the second direction.

[0072] The locking lever 48 can move between a locking position and a release position. In the example shown here, the locking lever 48 can pivot between the locking position and the release position. The locking lever 48 has a second pressing surface 43 and a guiding surface 51. The guiding surface 51 is arc-shaped. The second pressing surface 43 is a flat surface continuous with the guiding surface 51. When the locking lever 48 is in the locking position, the guiding surface 51 is at least partially located between the first side plate 33 and the second side plate 34, and the second pressing surface 43 is substantially perpendicular to the third direction and faces the second end of the drum unit 3 in the third direction. When the locking lever 48 is in the release position, the guiding surface 51 is further away from the second side plate 34 compared to when the locking lever 48 is in the locking position. When the developer cartridge 1 is inserted into the developer cartridge holder 30 of the drum unit 3, the second pressing surface 43 contacts the second projection 16 via the second ring 17. Thus, a pressing force is applied to the second projection 16 that points from the first end to the second end of the drum unit 3 in the third direction. The locking lever 48 prevents the developer cartridge 1 from being easily separated under impact or vibration.

[0073] The guide member 49 has a first guiding surface 44 and a second guiding surface 45. The guide member 49 is located on the inner surface of the first side plate 33. The guide member 49 projects from the inner surface of the first side plate 33 in the first direction. The first guiding surface 44 is a flat surface substantially perpendicular to the third direction. When the developer cartridge 1 rotates around the first projection 13, the guide member 49 contacts the first protrusion 18. Thus, the guide member 49 positions the developer cartridge 1 with respect to the drum unit 3.

[0074] The second guide surface 45 has a flat surface and an inclined surface continuous with the flat surface. The flat surface is generally perpendicular to a third direction. One end of the inclined surface in the second direction is connected to the flat surface. The inclined surface slopes from one end of the inclined surface in the second direction toward the other end of the inclined surface in the third direction. When the developer cartridge 1 rotates about the first protrusion 13, the second guide surface 45 is spaced apart from the first protrusion 18 in the third direction. This prevents significant misalignment between the developer cartridge 1 and the drum unit 3.

[0075] 5. Detailed structure of the locking device

[0076] The structure of the locking lever 48 according to this embodiment will now be described in detail. The locking device according to this embodiment includes the locking lever 48.

[0077] like Figures 8 to 10 As shown, the locking lever 48 is positioned corresponding to the developer cartridge 1 to be attached to the drum unit 3. The locking lever 48 located on the first side plate 33 is paired with a corresponding locking lever 48 located on the second side plate 34. The locking lever 48 located on the first side plate 33 will be described primarily without repeating the description of the locking lever 48 located on the second side plate 34.

[0078] The first side plate 33 has a plurality of openings 33a located at a first end (the end opposite to gravity) in a third direction. The plurality of openings 33a are spaced apart from each other in a second direction. Each opening 33a is rectangular and extends through the first side plate 33 in the first direction. In this embodiment, the first side plate 33 has four openings 33a to receive four developer cartridges 1 to be attached to the drum unit 3. A locking lever 48 is exposed through each opening 33a.

[0079] In detail, each opening 33a is defined by a first inner wall of the first side plate 33 located at a first end in a second direction and a second inner wall of the first side plate 33 located at a second end in a second direction. A locking lever 48 includes a pivot (not shown) located in a second direction between the first and second inner walls. The locking lever 48 is pivotable about the pivot.

[0080] The locking lever 48 includes an arcuate guide surface 51. The locking lever 48 is pivotable about a pivot axis between a locked position and a released position. When the locking lever 48 is in the locked position, the guide surface 51 is at least partially located between the first side plate 33 and the second side plate 34 in a first direction. When the locking lever 48 is in the released position, the guide surface 51 is further away from the first side plate 33 in the first direction compared to when the locking lever 48 is in the locked position.

[0081] The locking lever 48, in the locked position, applies pressure to the developer cartridge 1 attached to the drum unit 3, with the pressure pointing from a first end of the drum unit 3 facing upwards to a second end of the drum unit 3 facing upwards. This prevents the developer cartridge 1 from easily separating from the drum unit 3 under impact or vibration.

[0082] The locking lever 48 in the released position allows the developer cartridge 1 to be inserted into or removed from the developer cartridge holder 30 of the drum unit 3.

[0083] During the attachment of developer cartridge 1 to developer cartridge holder 30 of drum unit 3, guide surface 51 of locking lever 48 guides developer cartridge 1 (first outer surface 111 and second outer surface 112).

[0084] The locking lever 48 includes a spring (not shown) that applies a pressing force from a first end of the drum unit 3 pointing to a second end of the drum unit 3 pointing to a third-direction upward direction when the developer cartridge 1 is attached to the developer cartridge holder 30 of the drum unit 3. In other words, the locking lever 48 is continuously pressed toward the locked position by a spring force.

[0085] 6. The interaction forces of the attached developer cartridge

[0086] The main references are as follows Figures 8 to 15 Describes the forces that interact during the attachment of the developer cartridge 1 to the developer cartridge holder 30 of the drum unit 3.

[0087] To attach the developer cartridge 1 to the drum unit 3, the user first holds the developer cartridge 1 with the first end 113 of the housing 11 facing the third-facing second end of the drum unit 3 and the second end 114 of the housing 11 facing the third-facing first end of the drum unit 3. The user then moves the developer cartridge 1 from the third-facing first end of the drum unit 3 toward the third-facing second end of the drum unit 3 (see...). Figure 8 The developer cartridge holders (developer cartridge holder 30 on the first side plate 33 and developer cartridge holder on the second side plate 34) are inserted. As a result, the guide surface 51 of the locking lever 48 contacts the second protrusion 16 (second ring 17), causing the guide surface 51 of the locking lever 48 to pivot outward in the drum unit 3. In this way, the locking lever 48 pivots toward the release position and the end faces of the developer cartridge 1 (first outer surface 111 and second outer surface 112) are guided along the arcuate guide surface 51. As a result, the user smoothly pushes the developer cartridge 1 toward the third-upward second end of the drum unit 3.

[0088] Then, the first protrusion 13 is supported by the support surface 41 via the first ring 14. The support surface 41 bears the weight of the developer cartridge 1.

[0089] As the user pushes the developer cartridge 1 toward the third-upper end of the drum unit 3 during the movement of the locking lever 48 from the locked position to the released position against the pressure applied by the spring of the locking lever 48, the second protrusion 16 moves to the third-upper end of the drum unit 3 further than the locking lever 48. The locking lever 48 then pivots to the locked position under the pressure applied by its spring. The locking lever 48 then moves to the locked position under the pressure applied by its spring, thus causing the second pressing surface 43 to apply a pressing force to the second protrusion 16 (second ring 17) from the third-upper end of the drum unit 3 toward the third-upper end of the drum unit 3.

[0090] More specifically, the second protrusion 16 (second ring 17) contacts the second pressing surface 43 of the locking lever 48 in the locked position to receive a pressing force from the second pressing surface 43 in the third direction from the second end 114 of the housing 11 to the first end 113 of the housing 11. In this position, the first protrusion 13 is supported by a support surface 41 located at the second end of the drum unit 3 in the third direction. These opposing forces result in a torque in the developer cartridge 1 about the first protrusion 13. This causes the developer cartridge 1 to rotate slightly about the first protrusion 13 in the drum unit 3 and to move the developing roller 12 toward the photosensitive drum 31. As the developing roller 12 moves toward the photosensitive drum 31, the first protrusion 18 contacts the first guide surface 44 to prevent the developer cartridge 1 from rotating about the first protrusion 13. This determines the contact angle between the developing roller 12 and the photosensitive drum 31 and appropriately positions the developing roller 12 relative to the photosensitive drum 31. In other words, the developer cartridge 1 is located in the drum unit 3.

[0091] When the user inserts the developer cartridge 1 into the drum unit 3 from its first end in the third direction toward its second end in the third direction, the first pressing surface 42 is pushed by the first pressure receiving surface 15 against the pressing force of the spring of the pressing member 47 toward the second end in the second direction of the drum unit 3. Simultaneously or subsequently, as the developer cartridge 1 rotates slightly about the first protrusion 13, the first pressure receiving surface 15 receives from the first pressing surface 42 the pressing force in the second direction from the covering surface 12b toward the exposed surface 12a. In this position, the support surface 41 receives the weight of the developer cartridge 1 applied through the first protrusion 13. As the first protrusion 13 is supported by the support surface 41, the first protrusion 13 (first ring 14) thus slides toward the first end in the second direction of the drum unit 3. This causes the developing roller 12 to move further toward the photosensitive drum 31 and allows the outer peripheral surface of the developing roller 12 (developing roller body) to contact the outer peripheral surface of the photosensitive drum 31 with appropriate contact pressure. In this position, the support surface 41 bears the weight of the developer cartridge 1. The weight of the developer cartridge 1 is even less likely to affect the contact pressure between the developing roller 12 and the photosensitive drum 31. In other words, the contact pressure between the developing roller 12 and the photosensitive drum 31 is determined solely by the pressing force applied by the spring of the pressing member 47 and the pressing force applied by the spring of the locking lever 48. This prevents the contact pressure between the developing roller 12 and the photosensitive drum 31 from changing significantly depending on the remaining toner dosage in the developer cartridge 1.

[0092] Just before the outer peripheral surface of the developing roller 12 (developing roller body) contacts the outer peripheral surface of the photosensitive drum 31, the first protrusion 18 is held in a third-order direction between the first guide surface 44 and the second guide surface 45 (see...). Figure 10 This structure properly positions the developing roller 12 relative to the photosensitive drum 31. An inclined surface included in the second guide surface 45 smoothly guides the developing roller 12 between the first guide surface 44 and the second guide surface 45.

[0093] In the manner described above, when the developer cartridge 1 is attached to the drum unit 3, the developer cartridge 1 is properly positioned relative to the drum unit 3. When the developer cartridge 1 is attached to the drum unit 3, the locking lever 48 is in a locked position, restricting the developer cartridge 1 from moving toward the first end of the drum unit 3 in a third-direction upward direction (in the direction opposite to gravity). The second pressing surface 43 thus locks the developer cartridge 1. Therefore, the developer cartridge 1 will not easily separate from the drum unit 3 under vibration or impact applied to the image forming apparatus 100. The structure according to this embodiment allows for reliable attachment and removal of the developer cartridge 1 to and from the drum unit 3, as well as reliable locking.

[0094] In order to remove the developer cartridge 1 from the drum unit 3, during the movement of the first outer surface 111 and the second outer surface 112 along the curve of the arcuate guide surface 51, the locking lever 48 temporarily pivots toward the release position to move the developer cartridge 1 toward the first end of the drum unit 3 in a third-upward direction.

[0095] In this embodiment, the locking lever 48 is pivotable about a pivot axis extending in the second direction. The locking lever 48 switches between a locked position and a released position to attach or remove the developer cartridge 1 to or from the drum unit 3. This configuration allows each of the locking levers 48 to be positioned such that the first outer surface 111 or second outer surface 112 of the corresponding developer cartridge, held by the frame 38 when viewed in the first direction, completely overlaps with the locking lever 48. In other words, each of the locking levers 48 is integrally located between the third and fourth outer surfaces of the corresponding developer cartridge 1. The third outer surface extends in the first direction between the first and second outer surfaces. The fourth outer surface extends in the first direction between the first and second outer surfaces. The fourth outer surface is spaced apart from the third outer surface in the second direction. This eliminates the gap required for the locking levers 48 to pivot between adjacent developer cartridges 1 in the second direction, and thus allows adjacent developer cartridges 1 to be closer to each other. The drum unit 3 is reduced in size in the direction in which the photosensitive drum 31 is housed.

Claims

1. An image forming apparatus, characterized in that, Include: A frame, the frame including a first side plate and a second side plate, the first side plate being located at a first end of the frame in a first direction, and the second side plate being spaced apart from the first side plate in the first direction; Multiple developer cartridges are attached to the frame; and A plurality of locking levers, each corresponding to one of the plurality of developer cartridges, each locking lever being pivotable about a pivot axis extending in a second direction intersecting the first direction, and each locking lever being pivotable between a locked position, in which the developer cartridge held by the frame is locked to the frame, and in the released position, the developer cartridge is unlocked from the frame. Each of the locking levers is positioned such that, when viewed in the first direction, the first outer surface of the corresponding developer cartridge held by the frame overlaps with the locking lever.

2. The image forming apparatus as claimed in claim 1, characterized in that, in, Each of the locking levers is pivotable between the locked position and the released position.

3. The image forming apparatus as claimed in claim 1, characterized in that, in, Each of the locking levers is positioned such that, when viewed in the first direction, the first outer surface of the corresponding developer cartridge held by the frame completely overlaps with the locking lever.

4. The image forming apparatus as claimed in claim 1, characterized in that, It also includes multiple photosensitive drums, each of which is rotatable about a drum axis extending in the first direction.

5. The image forming apparatus as claimed in claim 4, characterized in that, in, The frame is rotatably supported in the first direction between the first side plate and the second side plate.

6. The image forming apparatus as claimed in claim 5, characterized in that, Each of the locking levers is pivotable between a locked position and a released position, in which the developer cartridge, held by the frame relative to the photosensitive drum, is locked to the frame, and in the released position, the developer cartridge is unlocked from the frame.

7. The image forming apparatus as claimed in claim 1, characterized in that, It also includes the main body casing; The frame holding the plurality of developer cartridges is configured to be mounted on the main body housing.

8. The image forming apparatus as claimed in claim 1, characterized in that, in, During the attachment of the corresponding developer cartridge to the frame, the corresponding locking lever pivots toward the release position.

9. The image forming apparatus as claimed in claim 8, characterized in that, in, During the attachment of the respective developer cartridge to the frame, after the respective locking lever pivots toward the release position, the locking lever pivots toward the locking position.

10. The image forming apparatus as claimed in claim 1, characterized in that, in, When the attachment of the corresponding developer cartridge to the frame is completed, the corresponding locking lever is positioned in the locked position.

11. The image forming apparatus as claimed in claim 1, characterized in that, in, The second direction is orthogonal to the first direction.

12. The image forming apparatus as claimed in claim 1, characterized in that, in, The locking lever is configured to bias in the third direction toward the developer cartridge held by the frame when the locking lever is in the locked position.

13. The image forming apparatus as claimed in claim 1, characterized in that, in, The locking lever includes a pressing surface configured to contact a portion of the developer cartridge when the locking lever is in the locked position, and to disengage from the portion of the developer cartridge when the locking lever is in the released position.

14. The image forming apparatus as claimed in claim 13, characterized in that, in, Compared to when the locking lever is in the locked position, when the locking lever is in the released position, the pressing surface is further away from the area between the first side plate and the second side plate in the first direction.

15. The image forming apparatus as claimed in claim 1, characterized in that, in, The locking lever includes a guide surface configured to guide the developer cartridge during attachment of the developer cartridge to the frame.

16. The image forming apparatus as claimed in claim 1, characterized in that, Further includes: A pressing member configured to press the developer cartridge held by the frame in the second direction.

17. The image forming apparatus as claimed in claim 16, characterized in that, It also includes multiple photosensitive drums, each of which is rotatable about a drum axis extending in the first direction. The pressing member is configured to be biased toward the photosensitive drum in the second direction.

18. The image forming apparatus as claimed in claim 17, characterized in that, in, When the developer cartridge is held by the frame, the pressing member is at a first distance from the photosensitive drum in the second direction, and when the developer cartridge is removed from the frame, the pressing member is at a second distance from the photosensitive drum in the second direction, the second distance being less than the first distance.

19. The image forming apparatus as claimed in claim 1, characterized in that, It also includes a drum unit, The drum unit includes a drum housing.

20. The image forming apparatus as claimed in claim 1, characterized in that, in, The locking lever includes a first locking lever and a second locking lever, and The first locking lever is located at the first side plate, and the second locking lever is located at the second side plate.

21. The image forming apparatus as claimed in claim 1, characterized in that, Further includes: Multiple photosensitive drums, each of which is rotatable about a drum axis extending in the first direction, and each of which is arranged along the second direction; and A plurality of locking levers, each corresponding to one of a plurality of developer cartridges, each locking lever being pivotable about a pivot axis extending in the second direction between a locked position and a released position, wherein the developer cartridge is locked to the frame in the locked position and the developer cartridge is unlocked from the frame in the released position.

Images