Developing cartridge capable of releasing meshing between gear and rack gear

Abstract

A developing cartridge includes: a casing; a developing roller; a developing electrode; a gear; a rack gear including a protrusion; and a cam having first and second cam surfaces. The rack gear meshes with the gear and is movable in a direction from one end toward another end of the casing. The cam is movable from a first position to a second position. The first cam surface of the cam at the first position contacts the protrusion, and causes the cam to move to the second position as the rack gear moves in the direction in a state where the first cam surface is in contact with the protrusion. A second cam surface moves the developing electrode in a direction away from the cam different from moving directions of the rack gear and the cam while contacting the developing electrode as the cam moves to the second position.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application inin, where the center portion of each of the surfaces 78A, 78B, 78C is defined relative to the direction from the one end E10 of the casing 11 toward the other end E20 of the casing 11. The recessed portion 78D is positioned between an edge of the first flat surface 78A closer to the casing 11 and an edge of the second flat surface 78B farther from the casing 11. Further, the spring support portion 78 has a side surface 78E closer to the casing 11. The spring support portion 78 includes an engagement claw 78F positioned at the side surface 78E and protruding from the side surface 78E.

The through-hole 63A of the third cover portion 63 of the gear cover 60 is formed to have a size corresponding to the spring electrode 80.

The spring electrode 80 is made of an electrically-conductive material. The spring electrode 80 is electrically connected to the developing roller 12. The spring electrode 80 is movable together with the cam 170. The spring electrode 80 includes a developing electrode 81 and a spring 82. The developing electrode 81 has a shape in conformance with the shape of the spring support portion 78. The spring 82 is formed integrally with the developing electrode 81.

The developing electrode 81 includes a first plate-like portion 81A, a second plate-like portion 81B, a third plate-like portion 81C, a fourth plate-like portion 81D, and a fifth plate-like portion 81E. The first plate-like portion 81A and the second plate-like portion 81B extend parallel with the base portion 71. The third plate-like portion 81C connects the first plate-like portion 81A and the second plate-like portion 81B. The fourth plate-like portion 81D extends from an end of the first plate-like portion 81A closer to the casing 11 toward the base portion 71. The fifth plate-like portion 81E extends from an end of the second plate-like portion 81B farther from the casing 11 toward the base portion 71.

The first plate-like portion 81A, the second plate-like portion 81B, and the third plate-like portion 81C are received by the recessed portion 78D of the spring support portion 78 and are positioned at a bottom surface of the recessed portion 78D.

In a state where the first plate-like portion 81A is positioned at the bottom surface of the recessed portion 78D, a surface of the first plate-like portion 81A opposite to a surface thereof facing the cam 170 is flush with the first flat surface 78A of the spring support portion 78. In a state where the second plate-like portion 81B is positioned at the bottom surface of the recessed portion 78D, a surface of the second plate-like portion 81B opposite to a surface thereof facing the cam 170 is flush with the second flat surface 78B of the spring support portion 78. In a state where the third plate-like portion 81C is positioned at the bottom surface of the recessed portion 78D, a surface of the third plate-like portion 81C opposite to a surface thereof facing the cam 170 is flush with the inclined surface 78C of the spring support portion 78.

Alternatively, in a state where the first plate-like portion 81A is positioned at the bottom surface of the recessed portion 78D, the surface of the first plate-like portion 81A opposite to the surface thereof facing the cam 170 is positioned farther from the base portion 71 than the first flat surface 78A of the spring support portion 78. In a state where the second plate-like portion 81B is positioned at the bottom surface of the recessed portion 78D, the surface of the second plate-like portion 81B opposite to the surface thereof facing the cam 170 is positioned farther from the base portion 71 than the second flat surface 78B of the spring support portion 78. In a state where the third plate-like portion 81C is positioned at the bottom surface of the recessed portion 78D, the surface of the third plate-like portion 81C opposite to the surface thereof facing the cam 170 is positioned farther from the base portion 71 than the inclined surface 78C of the spring support portion 78. Further, the surface of the third plate-like portion 81C inclined relative to the axial direction and opposite to the surface thereof facing the cam 170 serves as a second cam surface 81G.

The second cam surface 81G has a fifth edge E105, and a sixth edge E106. The sixth edge E106 is positioned farther away from the casing 11 than the fifth edge E105 is from the casing 11 in the axial direction. The second cam surface 81G is inclined so as to protrude toward the opening 62A in a direction from the sixth edge E106 toward the fifth edge E105.

The fourth plate-like portion 81D and the fifth plate-like portion 81E interpose the spring support portion 78 therebetween in the axial direction. An engagement hole 81F engages with the engagement claw 78F of the spring support portion 78. The fourth plate-like portion 81D has the engagement hole 81F.

The spring 82 includes a flat plate-like portion 82A, a first curved portion 82B, and a second curved portion 82C. The flat plate-like portion 82A extends parallel with the first plate-like portion 81A. The first curved portion 82B is curved so as to protrude away from the cam 170. The second curved portion 82C is curved so as to protrude toward the casing 11. The flat plate-like portion 82A extends toward the casing 11 from an end of the fourth plate-like portion 81D closer to the cam 170. The first curved portion 82B is connected to an end of the flat plate-like portion 82A closer to the casing 11. The second curved portion 82C extends from an end of the first curved portion 82B closer to the casing 11 in a direction away from the cam 170.

As illustrated in FIG. 13A, the spring 82 is positioned between the side surface 78E of the spring support portion 78 and the bearing 40. An end of the spring 82 closer to the casing 11 is in contact with the bearing 40. The spring 82 urges the cam 170 in the direction away from the casing 11 in the axial direction in a state where the cam 170 is at its initial position (i.e. the position illustrated in FIG. 13A). That is, the spring 82 urges the cam 170 from the initial position as an example of a first position toward an outside position as an example of a second position.

As illustrated in FIG. 11B, the rack gear 150 includes the main body portion 51, the rack gear portion 52, and a cam portion 55. The cam portion 55 is not included in the rack gear 50 according to the first embodiment, while the main body portion 51 and the rack gear portion 52 of the rack gear 150 are similar to those of the rack gear 50 according to the first embodiment. The cam portion 55 is positioned at an upstream portion of the rack gear 150 in a moving direction of the rack gear 150 in an end portion of the main body portion 51 farther from the casing 11 in the axial direction. In the following description, “upstream in the moving direction of the rack gear” and “downstream in the moving direction of the rack gear” will also be simply referred to as “upstream” and “downstream”, respectively.

The cam portion 55 protrudes from the main body portion 51. A surface of the cam portion 55 closer to the casing 11 includes a first holding surface 55A, a second holding surface 55B, a third holding surface 55C, a connecting surface 55D, and a cam surface 55E. The first holding surface 55A, the second holding surface 55B, and the third holding surface 55C are planer surfaces orthogonal to the axial direction. The connecting surface 55D connects the first holding surface 55A and the second holding surface 55B. The cam surface 55E connects the second holding surface 55B and the third holding surface 55C.

The first holding surface 55A and the third holding surface 55C are positioned at positions the same as each other in the axial direction. The first holding surface 55A is positioned downstream relative to the third holding surface 55C. The first holding surface 55A and the third holding surface 55C come into contact with the protrusion 77 to hold the cam 170 at the initial position (first position).

The second holding surface 55B is positioned between the first holding surface 55A and the third holding surface 55C in the moving direction of the rack gear 150. The second holding surface 55B is positioned farther away from the casing 11 than the first holding surface 55A is from the casing 11 (see FIG. 12A). The second holding surface 55B comes into contact with the protrusion 77 to hold the cam 170 at the outside position (second position).

The connecting surface 55D extends from an upstream edge of the first holding surface 55A and is connected to a downstream edge of the second holding surface 55B. The connecting surface 55D is inclined so that an upstream edge of the connecting surface 55D is positioned farther away from the casing 11 than a downstream edge of the connecting surface 55D is from the casing 11.

The cam surface 55E is inclined relative to the moving direction of the rack gear 150. Specifically, the cam surface 55E extends from an upstream edge of the second holding surface 55B and is connected to a downstream edge of the third holding surface 55C. The cam surface 55E is inclined so that an upstream edge of the cam surface 55E is positioned closer to the casing 11 than a downstream edge of the cam surface 55E is to the casing 11.

In this embodiment, as illustrated in FIG. 12A, in a case where the developing cartridge 1 is in a brand-new state, the cam 170 is at its initial position since the protrusion 77 of the cam 170 is supported at the first holding surface 55A of the rack gear 150. Specifically, an urging force applied to the cam 170 from the spring electrode 80 is received by the first holding surface 55A.

In a case where the developing cartridge 1 is attached to the main body casing of the image forming apparatus in a state where the cam 170 is at the initial position, the actuator AC is pushed by the second plate-like portion 81B of the spring electrode 80 supported at the cam 170 as illustrated in FIG. 13A. As a result, the actuator AC swingably moves from a first posture to a second posture. The optical sensor detects the change in posture of the actuator AC. At this time, the electrode of the actuator AC and the spring electrode 80 are electrically connected to each other.

Thereafter, as illustrated in the sequence of FIGS. 12A and 12B, in a case where the driving force is transmitted to the agitator gear 31, the rack gear 150 moves in the direction from the one end E10 of the casing 11 toward the other end E20 of the casing 11. In a case where the first holding surface 55A separates from the protrusion 77 in accordance with the movement of the rack gear 150, the cam 170 moves in the direction away from the casing 11 in the axial direction due to the urging force of the spring electrode 80. Thereafter, in a case where the protrusion 77 comes into contact with the second holding surface 55B, the movement of the cam 170 is stopped, and the cam 170 is placed at the outside position farther away from the casing 11 than the initial position from the casing 11.

While the cam 170 moves from the initial position to the outside position, the actuator AC is pushed by the inclined third plate-like portion 81C of the spring electrode 80 supported at the cam 170 as illustrated in FIG. 13B. As a result, the actuator AC swingably moves from the second posture to a third posture, and the optical sensor detects the change in posture of the actuator AC.

Thereafter, as illustrated in the sequence of FIGS. 12B and 12C, in a case where the rack gear 150 further moves in the direction from the one end E10 of the casing 11 toward the other end E20 of the casing 11, the cam 170 returns to the initial position from the outside position since the protrusion 77 is pushed by the cam surface 55E of the rack gear 150 in the direction toward the casing 11 in the axial direction against the urging force of the spring electrode 80. As a result, the actuator AC swingably moves from the third posture to the second posture as illustrated in FIG. 13A, and the optical sensor detects the change in posture of the actuator AC.

As described above, in the second embodiment, similarly to the first embodiment, meshing between the rack gear 150 and the agitator gear 31 can be released since the rack gear 150 moves in the direction from the one end E10 of the casing 11 toward the other end E20 of the casing 11. Further, in the second embodiment, since the spring 82 and the developing electrode 81 are configured as a single component (spring electrode 80), the number of components can be reduced. The spring and the developing electrode may be separate components. Further, the spring as a separate component may be a coil spring or a wire spring.

<Modifications>

While the description has been made in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that many modifications and variations may be made therein without departing from the scope of the disclosure.

In the first embodiment, the fourth cam surfaces 24A are provided at the developing electrode 20, and the second cam surfaces 76A are provided at the cam 70. However, for example, a protrusion engaging with the second cam surface of the cam may be provided at the developing electrode.

In the first embodiment, the rack gear 50 in its entirety is covered with the gear cover 60. However, the gear cover may cover a portion of the rack gear and may expose the remaining portion of the rack gear to outside.

In the first and second embodiments, the agitator gear 31 is exemplified as an example of a gear. However, any gears other than the agitator gear 31 may be available.

In the first and second embodiment, the compression coil spring SP and the spring 82 are exemplified as a spring. However, the spring may be, for example, a wire spring or a torsion spring.

In the first embodiment, the cam 70 is movably supported at the gear cover 60. However, the cam may be movably supported at the casing.

Further, the respective elements described in the above embodiments and modifications may be arbitrarily combined and implemented.

Claims

1. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at one end of the casing;

a developing electrode electrically connected to the developing roller;

a gear rotatable about a second axis parallel with the first axis;

a rack gear meshing with the gear, the rack gear being movable in a direction from the one end of the casing toward another end of the casing opposite to the one end of the casing, the rack gear including a protrusion; and

a cam movable from a first position to a second position, the second position being farther away from the casing than the first position is from the casing in the axial direction, the cam having:

a first cam surface contacting the protrusion in a case where the cam is at the first position, the first cam surface causing the cam to move from the first position to the second position in a case where the rack gear moves in the direction from the one end of the casing toward the another end of the casing in a state where the first cam surface is in contact with the protrusion; and

a second cam surface moving the developing electrode in a direction away from the cam while contacting the developing electrode in a case where the cam moves from the first position to the second position, the direction away from the cam being a direction different from a moving direction of the rack gear and a moving direction of the cam.

2. The developing cartridge according to claim 1, further comprising a spring for electrically connecting the developing electrode to the developing roller.

3. The developing cartridge according to claim 2, further comprising a bearing for supporting the developing roller,

wherein the spring has:

one end in contact with the developing electrode; and

another end opposite to the one end of the spring, the another end being in contact with the bearing.

4. The developing cartridge according to claim 3, wherein, in a state where the one end of the spring is in contact with the developing electrode and the another end of the spring is in contact with the bearing, the spring has a length smaller than a natural length of the spring.

5. The developing cartridge according to claim 3, wherein the bearing is made of an electrically-conductive resin.

6. The developing cartridge according to claim 1, wherein the developing electrode is made of an electrically-conductive resin.

7. The developing cartridge according to claim 1, wherein the first cam surface has:

a first edge; and

a second edge positioned farther away from the casing than the first edge is from the casing in the axial direction, and

wherein the first cam surface is inclined so that the first edge is positioned downstream relative to the second edge in the moving direction of the rack gear.

8. The developing cartridge according to claim 1, wherein the cam has a third cam surface positioned downstream relative to the first cam surface in the moving direction of the rack gear, the third cam surface contacting the protrusion in a case where the cam is at the second position, and

wherein the third cam surface causes the cam to move from the second position to the first position in a case where the rack gear moves in the direction from the one end of the casing toward the another end of the casing in a state where the third cam surface is in contact with the protrusion.

9. The developing cartridge according to claim 8, wherein the third cam surface has:

a third first edge; and

a fourth second edge positioned farther away from the casing than the third first edge is from the casing in the axial direction, and

wherein the third cam surface is inclined so that the fourth second edge of the third cam surface is positioned downstream relative to the third first edge of the third cam surface in the moving direction of the rack gear.

10. The developing cartridge according to claim 8, wherein the first cam surface is positioned at a position different from the third cam surface in the moving direction of the cam.

11. The developing cartridge according to claim 1, further comprising:

an agitator configured to agitate toner accommodated in the casing; and

an agitator gear mounted to an end portion of the agitator and rotatable together with the agitator,

wherein the agitator gear serves as the gear.

12. The developing cartridge according to claim 1, further comprising a coupling positioned opposite to the developing electrode relative to the casing.

13. The developing cartridge according to claim 1, wherein the developing gear has a fourth further cam surface contacting the second cam surface and extending parallel with the second cam surface.

14. The developing cartridge according to claim 1, wherein the rack gear includes:

a main body portion having a plate shape and extending in the moving direction of the rack gear; and

a plurality of gear teeth meshing with the gear, and

wherein the plurality of gear teeth and the protrusion protrude from the main body portion and are positioned at positions different from each other in the moving direction of the rack gear.

15. The developing cartridge according to claim 14, wherein the protrusion is positioned at a position different from the plurality of gear teeth in the axial direction.

16. The developing cartridge according to claim 1, wherein the second cam surface has:

a fifth first edge; and

a sixth second edge positioned farther away from the casing than the fifth first edge of the second cam surface is from the casing in the axial direction, and

wherein the second cam surface is inclined so as to protrude toward the developing electrode in a direction from the sixth second edge of the second cam surface toward the fifth first edge of the second cam surface.

17. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at one end of the casing;

a gear rotatable about a second axis extending in the axial direction;

a developing electrode electrically connected to the developing roller;

a rack gear movable from the one end of the casing toward another end of the casing opposite to the one end of the casing, the rack gear being movable in a direction from the one end of the casing toward the another end of the casing in accordance with rotation of the gear by meshing with the gear, the rack gear including a protrusion;

a cover covering at least a portion of the rack gear, the cover having an opening through which the developing electrode is exposed to an outside; and

a cam movable from a first position to a second position, the second position being farther away from the casing than the first position is from the casing in the axial direction, the cam having:

a first cam surface having a first edge and a second edge, the second edge being positioned farther away from the casing than the first edge is from the casing in the axial direction, the first cam surface being inclined so that the first edge is positioned downstream relative to the second edge in a moving direction of the protrusion, the first cam surface causing the cam to move from the first position to the second position by engaging with the protrusion, the first cam surface being positioned outside of a movement locus of the protrusion in a case where the cam is at the second position; and

a second cam surface movable together with the first cam surface, the second cam surface being positioned farther away from the casing than the first cam surface is from the casing in the axial direction, the second cam surface being movable while contacting the developing electrode, the second cam surface having a fifth first edge and a sixth second edge, the sixth second edge of the second cam surface being positioned farther away from the casing than the fifth first edge of the second cam surface is from the casing in the axial direction, the second cam surface being inclined so as to protrude toward the opening in a direction from the sixth second edge of the second cam surface toward the fifth first edge of the second cam surface.

18. The developing cartridge according to claim 17, further comprising a spring for electrically connecting the developing electrode to the developing roller.

19. The developing cartridge according to claim 17, wherein the cam further includes a third cam surface positioned downstream relative to the first cam surface in a moving direction of the rack gear, the third cam surface being positioned within the movement locus of the protrusion in a case where the cam is at the second position,

wherein the third cam surface has:

a third first edge; and

a fourth second edge positioned farther away from the casing than the third first edge of the third cam surface is from the casing in the axial direction, and

wherein the third cam surface is inclined so that the fourth second edge of the third cam surface is positioned downstream relative to the third first edge of the third cam surface in the moving direction of the rack gear.

20. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at one end of the casing;

a gear rotatable about a second axis parallel with the first axis;

a rack gear meshing with the gear, the rack gear being movable in a direction from the one end of the casing toward another end of the casing opposite to the one end of the casing;

a cam movable from a first position to a second position, the second position being farther away from the casing than the first position is from the casing in the axial direction, the cam including a protrusion;

a spring urging the cam from the first position toward the second position;

a cover having an opening; and

a developing electrode electrically connected to the developing roller, the developing electrode being movable together with the cam, the developing electrode having a second cam surface, the second cam surface having a fifth first edge and a sixth second edge, the sixth second edge being positioned farther away from the casing than the fifth first edge is from the casing in the axial direction, the second cam surface being inclined so as to protrude toward the opening in a direction from the sixth second edge toward the fifth first edge,

the rack gear having:

a first holding surface contacting the protrusion to hold the cam at the first position; and

a second holding surface contacting the protrusion to hold the cam at the second position.

21. The developing cartridge according to claim 20, wherein the developing electrode is formed integrally with the spring.

22. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at a first end of the casing;

a developing electrode electrically connected to the developing roller;

a gear rotatable about a second axis parallel with the first axis;

a rack gear meshing with the gear, the rack gear being movable in a direction extending between the first end of the casing and a second end of the casing opposite to the first end of the casing, the rack gear including a protrusion; and

a cam movable between a first position and a second position, the cam having:

a first cam surface configured to engage the protrusion to selectively move the cam between the first and second positions in response to movement of the rack gear.

23. The developing cartridge according to claim 22, wherein the rack gear is movable in a direction extending from the first end of the casing to the second end of the casing to move the cam from the first position to the second position.

24. The developing cartridge according to claim 22, wherein the cam further includes a second cam surface that moves the developing electrode in a direction away from the cam in response to the movement of the cam from the first position to the second position.

25. The developing cartridge according to claim 22, wherein the second position is farther away from the casing than the first position is from the casing in the axial direction.

26. The developing cartridge according to claim 22, wherein the cam is configured to move the developing electrode in a direction away from the cam in response to the movement of the cam from the first position to the second position, the direction away from the cam being a direction different from a moving direction of the rack gear and a moving direction of the cam.

27. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at a first end of the casing;

a developing electrode electrically connected to the developing roller;

a gear rotatable about a second axis parallel with the first axis;

a rack gear meshing with the gear, the rack gear including a protrusion; and

a cam movable from a first position to a second position, the cam having a first cam surface contacting the protrusion in a case where the cam is at the first position, the first cam surface causing the cam to move from the first position to the second position in a case where the rack gear moves in a direction extending between the first end of the casing and a second end of the casing opposite to the first end of the casing.

28. The developing cartridge according to claim 27, wherein the protrusion contacts the first cam surface as the rack gear moves in the direction extending from the first end of the casing toward the second end of the casing.

29. The developing cartridge according to claim 27, wherein the second position is farther away from the casing than the first position is from the casing in the axial direction.

30. The developing cartridge according to claim 27, wherein the cam further includes a second cam surface moving the developing electrode in a direction away from the cam while contacting the developing electrode in a case where the cam moves from the first position to the second position, the direction away from the cam being a direction different from a moving direction of the rack gear and a moving direction of the cam.

31. A developing cartridge comprising:

a casing configured to accommodate toner therein;

a developing roller rotatable about a first axis extending in an axial direction, the developing roller being positioned at one end of the casing;

a developing electrode electrically connected to the developing roller;

a gear rotatable about a second axis parallel with the first axis;

a rack gear meshing with the gear and being movable in a direction extending between the one end of the casing and another end of the casing opposite the one end of the casing; and

a cam movable from a first position to a second position, the cam being movable from the first position to the second position to move the developing electrode in a case where the rack gear moves in the direction extending between the one end of the casing and the another end of the casing opposite to the one end of the casing.

32. The developing cartridge according to claim 31, wherein the rack gear includes a protrusion and the cam includes a cam surface, the cam surface being contacted by the protrusion to cause the cam to move from the first position to the second position in a case where the rack gear moves in the direction between the one end of the casing and the another end of the casing opposite to the one end of the casing.

33. The developing cartridge according to claim 32, wherein the cam surface moves the developing electrode in a direction away from the cam in a case where the cam moves from the first position to the second position.

34. The developing cartridge according to claim 31, wherein the second position is farther away from the casing than the first position is from the casing in the axial direction.

35. The developing cartridge according to claim 31, wherein the cam further includes a cam surface configured to move the developing electrode in a direction away from the cam while contacting the developing electrode in a case where the cam moves from the first position to the second position, the direction away from the cam being a direction different from a moving direction of the rack gear and a moving direction of the cam.