Drum Cartridge

Abstract

To prevent a reduction in urging force to pull an electrification wire of a torsion spring, while preventing an increase in size of a drum cartridge in a second direction.SOLUTION: A drum cartridge 50 comprises: a photoreceptor drum 51 that is rotatable about a drum axis X1 extending in a first direction; an electrification wire 52A for electrifying the photoreceptor drum 51, the electrification wire 52A extending in the first direction; a torsion spring 54 that pulls the electrification wire 52A, the torsion spring 54 having a coil part 54A centered on an axis X2 along a second direction intersecting with the first direction; and a drum frame 55. The outer diameter of the coil part 54A is longer than the length in the second direction of the coil part 54A. The drum frame 55 has a boss 55A that extends in the second direction, the boss 55A fitted into the coil part 54A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a drum cartridge with a charged wire. [Background technology]

[0002] Conventionally, a drum cartridge is known that includes a charging wire that charges a photosensitive drum and a torsion spring that pulls the charging wire (see Patent Document 1). In this technology, the charging wire extends in a first direction. The torsion spring has a coil portion centered on an axis along a second direction perpendicular to the first direction. The length of the coil portion in the second direction is greater than the outer diameter of the coil portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-039139 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, the length of the coil portion in the second direction is greater than the outer diameter of the coil portion, which may result in an increase in the size of the drum cartridge in the second direction. Therefore, in order to prevent the drum cartridge from becoming larger in the second direction, it is conceivable to shorten only the length of the coil portion in the second direction while maintaining the outer diameter of the coil portion. However, if the length of the coil portion in the second direction is shortened while maintaining the outer diameter of the coil portion, there is a risk that the biasing force that pulls the charging wire of the torsion spring will become weaker.

[0005] Therefore, an object of the present disclosure is to prevent the drum cartridge from becoming larger in size in the second direction, while preventing the biasing force of the torsion spring that pulls the charging wire from becoming smaller. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the drum cartridge of the present disclosure includes a photosensitive drum rotatable about a drum axis extending in a first direction, a charging wire for charging the photosensitive drum, the charging wire extending in the first direction, a torsion spring for pulling the charging wire, the torsion spring having a coil portion centered on an axis along a second direction intersecting the first direction, and a drum frame. The outer diameter of the coil portion is greater than the length of the coil portion in the second direction, and the drum frame has a boss that extends in the second direction and enters the coil portion.

[0007] According to this configuration, by making the outer diameter of the coil part longer than the length of the coil part in the second direction, it is possible to prevent the drum cartridge from becoming large in size in the second direction and to ensure the biasing force that pulls the charging wire. Also, since the drum frame has a boss that fits into the coil part, the boss can prevent the torsion spring from shifting out of position.

[0008] Additionally, an outer diameter of the coil portion may be 1.5 times or more the length of the coil portion in the second direction.

[0009] The second direction may be perpendicular to the first direction.

[0010] Additionally, an outer diameter of the coil portion may be three or more times the length of the coil portion in the second direction.

[0011] Additionally, an outer diameter of the coil portion may be five times or more the length of the coil portion in the second direction.

[0012] The boss may also hold the coil portion.

[0013] The charged wire may have a straight portion extending in the first direction, and the boss may overlap the straight portion in the first direction.

[0014] The drum cartridge may be detachably attached to a main body housing having a main body electrode, and the torsion spring may have a charged electrode in contact with the main body electrode.

[0015] The drum cartridge may further include a cover that covers the torsion spring from the second direction, and the cover may have an arc-shaped rib that extends along an outer periphery of the coil portion.

[0016] According to this configuration, for example, when a conductive member of another cartridge is adjacent to the outside of the cover, the rib can increase the insulation distance between the conductive member and the coil portion.

[0017] The rib may be made of an insulating resin.

[0018] The cover may be made of an insulating resin.

[0019] The number of turns of the coil portion may be 3 or less.

[0020] The number of turns of the coil portion may be two or less.

[0021] The torsion spring may be connected to one end of the charging wire in the first direction.

[0022] The torsion spring may be configured to pull the charged wire in a direction different from the first direction. Effect of the Invention

[0023] According to the present disclosure, it is possible to prevent the drum cartridge from becoming large in size in the direction perpendicular to the charging wire. [Brief description of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing a color printer including a drum cartridge according to an embodiment of the present disclosure. [Diagram 2] FIG. 1A is a perspective view showing the structure around the torsion spring, and FIG. 1B is a perspective view showing the state in which the cover is attached to the drum frame. [Diagram 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the structure around the torsion spring. [Diagram 5] FIG. [Figure 6] FIG. 4 is a plan view showing a part of the cover in section. [Figure 7] 1A and 1B are a perspective view and a plan view showing a modified example of the first rib. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, the color printer 1 includes a main body housing 10, a sheet supply section 20, an image forming section 30, and a discharge section 90.

[0026] The main body housing 10 has an opening 10A and an upper cover 11. The opening 10A is an opening through which a process cartridge 40, which will be described later, can pass. The upper cover 11 is a cover for opening and closing the opening 10A. The upper surface of the upper cover 11 serves as a discharge tray 11A onto which the sheet S discharged from the main body housing 10 is discharged. The upper cover 11 has an LED mounting member 11B that holds the LED unit 31.

[0027] The sheet supply unit 20 includes a supply tray 21 and a sheet conveying roller 22. The supply tray 21 stores the sheet S. The sheet conveying roller 22 conveys the sheet S from the supply tray 21 toward the photoconductor drum 51.

[0028] The image forming section 30 includes four LED units 31, four process cartridges 40, a transfer unit 70, and a fixing device 80.

[0029] The LED unit 31 includes a plurality of LEDs (not shown) that expose the photoconductor drum 51. The LED unit 31 is rotatably connected to the LED mounting member 11B.

[0030] The process cartridges 40 are arranged side by side in the front-rear direction between the upper cover 11 and the sheet supply unit 20. The process cartridge 40 includes a drum cartridge 50 and a developing cartridge 60. The drum cartridge 50 is detachably attached to the main body housing 10. The drum cartridge 50 includes a photosensitive drum 51, a charger 52, and a cleaning roller 53.

[0031] The photoconductor drum 51 is rotatable about a drum axis X1 that extends in a first direction. The charger 52 includes a charging wire 52A for charging the photoconductor drum 51. The charging wire 52A extends in a first direction.

[0032] The cleaning roller 53 is a roller for cleaning the photosensitive drum 51. The cleaning roller 53 is in contact with the photosensitive drum 51.

[0033] The developing cartridge 60 is detachably attached to the drum cartridge 50. The developing cartridge 60 is configured to include a developing roller 61, a supply roller 62, and a toner storage chamber 63.

[0034] The developing roller 61 is a roller that supplies toner to the photoconductor drum 51. The supply roller 62 is a roller that supplies toner to the developing roller 61.

[0035] The transfer unit 70 includes a drive roller 71, a driven roller 72, a conveyor belt 73, and four transfer rollers 74. The drive roller 71 and the driven roller 72 are rollers for rotating the conveyor belt 73. The conveyor belt 73 is an endless belt. The transfer roller 74 is disposed inside the conveyor belt 73. The transfer roller 74 sandwiches the conveyor belt 73 between itself and the photosensitive drum 51.

[0036] The fixing device 80 includes a heating roller 81 and a pressure roller 82. The heating roller 81 is a roller that fixes a toner image onto the sheet S conveyed from the photosensitive drum 51. The pressure roller 82 sandwiches the sheet S between the heating roller 81 and the pressure roller 82.

[0037] In the image forming unit 30, the charger 52 charges the surface of the photoconductor drum 51. After that, the LED unit 31 exposes the surface of the photoconductor drum 51 to light. As a result, an electrostatic latent image is formed on the photoconductor drum 51.

[0038] The supply roller 62 and the developing roller 61 supply the toner in the toner storage chamber 63 to the electrostatic latent image on the photosensitive drum 51. As a result, a toner image is formed on the photosensitive drum 51.

[0039] The conveyor belt 73 conveys the sheet S. The sheet S passes between the photosensitive drum 51 and the transfer roller 74. At this time, the toner image on the photosensitive drum 51 is transferred to the sheet S. Thereafter, the sheet S passes between the heating roller 81 and the pressure roller 82. At this time, the toner image transferred onto the sheet S is thermally fixed onto the sheet S.

[0040] The discharge section 90 includes discharge rollers 91. The discharge rollers 91 discharge the sheet S conveyed from the fixing device 80 onto a discharge tray 11A.

[0041] 2(a) and (b), the drum cartridge 50 further includes a torsion spring 54, a drum frame 55, and a cover 56. The torsion spring 54 is made of, for example, a metal. The drum frame 55 is made of, for example, a non-conductive resin. The cover 56 is made of, for example, an insulating resin.

[0042] The torsion spring 54 is a spring that pulls the charged wire 52 A. The torsion spring 54 has a coil portion 54A, a first arm portion 54B, and a second arm portion 54C.

[0043] The coil portion 54A is a coil portion having an axis X2 that is aligned along a second direction intersecting the first direction. Preferably, the second direction is perpendicular to the first direction. In this embodiment, the second direction is perpendicular to the first direction.

[0044] The drum frame 55 has a boss 55A. The boss 55A extends in the second direction. The boss 55A enters the coil portion 54A. More specifically, the boss 55A fits into the coil portion 54A. The boss 55A holds the coil portion 54A.

[0045] 3, the outer diameter D1 of the coil portion 54A is longer than the length L1 of the coil portion 54A in the second direction. The outer diameter D1 is preferably 1.5 times or more, more preferably 3 times or more, and even more preferably 5 times or more, of the length L1. The upper limit of the outer diameter D1 is preferably 7 times or less of the length L1.

[0046] The number of turns of the coil portion 54A is preferably 3 turns or less, and more preferably 2 turns or less. Here, the number of turns refers to the number of turns of the coil portion 54A in a state where it is fitted into the boss 55A of the drum frame 55.

[0047] 2(a), the first arm portion 54B is connected to one end of the charged wire 52A in the first direction. The second arm portion 54C has a charged electrode 54D that contacts the main body electrode 12 (see FIG. 6) described later.

[0048] As shown in FIGS. 2(a) and 2(b), the cover 56 covers the torsion spring 54 from the second direction. As shown in FIG. 4, the drum cartridge 50 further includes a conductive spring 57 for supplying electricity to the developing roller 61. The conductive spring 57 contacts a main body contact of the main body housing 10 (not shown) when the drum cartridge 50 is mounted in the main body housing 10. The conductive spring 57 contacts a developing electrode of the developing cartridge 60 (not shown) when the developing cartridge 60 is mounted in the drum cartridge 50. The developing roller 61 is electrically connected to a developing electrode (not shown). That is, when the drum cartridge 50 with the developing cartridge 60 mounted is mounted in the main body housing 10, the main body contact of the main body housing 10 (not shown) is electrically connected to the developing roller 61 via the conductive spring 57 and the developing electrode of the developing cartridge 60 (not shown). The conductive spring 57 is located upstream of the drum axis X1 in the transport direction of the sheet S transported by the photosensitive drum 51. The torsion spring 54 is located downstream of the drum axis X1 in the conveying direction.

[0049] When the conductive spring 57 and the torsion spring 54 are arranged in this manner, there is a risk of discharge between two drum cartridges 50 adjacent in the transport direction. This problem will be described below. In the following description, of the two drum cartridges 50 adjacent in the transport direction, the upstream drum cartridge 50 will also be referred to as the "first drum cartridge 50X" and the downstream drum cartridge 50 will also be referred to as the "second drum cartridge 50Y." In the following description, the reference numbers of the members constituting the first drum cartridge 50X may be suffixed with "X" and the reference numbers of the members constituting the second drum cartridge 50Y may be suffixed with "Y" to distinguish them from each other.

[0050] When the conductive spring 57 is located upstream of the drum axis X1 in the transport direction of the sheet S transported by the photosensitive drum 51, and the torsion spring 54 is located downstream of the drum axis X1 in the transport direction, the torsion spring 54 of the first drum cartridge 50X is disposed near the conductive spring 57 of the second drum cartridge 50Y in a state in which the first drum cartridge 50X and the second drum cartridge 50Y are mounted in the main body housing 10. This makes it difficult to ensure an insulation distance between the torsion spring 54X of the first drum cartridge 50X and the conductive spring 57Y of the second drum cartridge 50Y. Therefore, there is a risk of discharge between the torsion spring 54X and the conductive spring 57Y. In contrast, in this embodiment, the insulating cover 56 covers the torsion spring 54 from the second direction, thereby suppressing discharge between the torsion spring 54X and the conductive spring 57Y.

[0051] As shown in Fig. 5, the cover 56 has a first portion 56A, a second portion 56B, a third portion 56C, a first rib 56D as an example of a rib, and a second rib 56E. The cover 56 is made of an insulating resin. As shown in Fig. 2, the first portion 56A covers the coil portion 54A. As shown in Fig. 4, the first portion 56A contacts the tip of the boss 55A.

[0052] 2, the second portion 56B covers the first arm portion 54B. The third portion 56C covers the second arm portion 54C. The third portion 56C has a hole H1. The hole H1 exposes the charged electrode 54D from the cover 56.

[0053] As shown in FIG. 5, the first rib 56D and the second rib 56E protrude from the first portion 56A toward the drum frame 55. As shown in FIG. 6, the first rib 56D is an arc-shaped rib along the outer periphery of the coil portion 54A. The first rib 56D covers approximately half of the outer periphery of the coil portion 54A. The second rib 56E is a linear rib along the first direction. The coil portion 54A is located between the first rib 56D and the second rib 56E in a third direction intersecting the first direction and the second direction. Preferably, the third direction is perpendicular to the first direction and the second direction. In this embodiment, the third direction is perpendicular to the first direction and the second direction.

[0054] The drum frame 55 has a clamping portion 55B that clamps the charged wire 52A in the third direction. Although not shown, the clamping portions 55B are disposed at one end of the charged wire 52A in the first direction and the other end of the charged wire 52A in the first direction. In detail, the clamping portion 55B has a first clamping portion 55B1 located at one end of the charged wire 52A in the first direction and a second clamping portion 55B2 (not shown) located at the other end of the charged wire 52A in the first direction.

[0055] The charged wire 52A has a straight portion W1 extending in a first direction and an inclined portion W2 inclined with respect to the straight portion W1. The straight portion W1 extends in the first direction over the range from the first clamping portion 55B1 to the second clamping portion 55B2.

[0056] The inclined portion W2 is inclined with respect to the straight portion W1 by being pulled by the torsion spring 54. In other words, the torsion spring 54 is configured to pull the charged wire 52A in a direction different from the first direction.

[0057] The inclined portion W2 has a ring-shaped ring portion W21 into which a part of the torsion spring 54 is inserted. The outer diameter of the boss 55A and the outer diameter of the coil portion 54A are larger than the outer diameter of the ring portion W21.

[0058] The boss 55A overlaps with the straight portion W1 in the first direction. In other words, the straight portion W1 is located within the range of the boss 55A in the third direction.

[0059] The main body housing 10 has a main body electrode 12. The main body electrode 12 is an electrode for supplying electricity to the charged wire 52A via the torsion spring 54. When the drum cartridge 50 is attached to the main body housing 10, the main body electrode 12 comes into contact with the charged electrode 54D of the torsion spring 54.

[0060] As described above, the following effects can be obtained in this embodiment. By making the outer diameter D1 of the coil portion 54A longer than the length L1 of the coil portion 54A in the second direction, it is possible to prevent the drum cartridge 50 from becoming large in size in the second direction and to ensure the biasing force that pulls the charging wire 52A. In addition, since the drum frame 55 has a boss 55A that fits into the coil portion 54A, the boss 55A can prevent the torsion spring 54 from shifting in position.

[0061] Since the cover 56 has the first rib 56D and the second rib 56E, it is possible to increase the insulation distance between the conductive spring 57Y of the second drum cartridge 50Y adjacent to the outside of the cover 56 and the coil portion 54A of the first drum cartridge 50X.

[0062] The present disclosure is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0063] In the above embodiment, the first rib 56D covering approximately half of the outer circumference of the coil portion 54A is exemplified as the arc-shaped rib, but the present invention is not limited thereto. The length of the arc-shaped rib in the circumferential direction of the coil portion can be set arbitrarily. For example, as shown in Figs. 7(a) and (b), the length of the arc-shaped rib in the circumferential direction of the coil portion 54A (hereinafter also referred to as "arc rib 561") may be set to a length covering approximately 1 / 4 of the outer circumference of the coil portion 54A. Specifically, in the second embodiment shown in Fig. 7, the drum cartridge 50 has a first rib 56F different from that in the above embodiment.

[0064] The first rib 56F has an arc rib 561, and a linear first rib 562, a second rib 563, and a third rib 564. The first linear rib 562 is located on the opposite side of the coil portion 54A from the second rib 56E in the third direction. The first linear rib 562 extends in the first direction.

[0065] The arc rib 562 is located on the opposite side to the charged wire 52A in the first direction with respect to the first linear rib 562. The arc rib 562 extends in an arc shape from one end of the first linear rib 562 in the first direction toward the second rib 56E.

[0066] The second linear rib 562 extends in the third direction from the other end of the first linear rib 562 in the first direction toward the second rib 56E. The third linear rib 563 extends in the first direction from the end of the second linear rib 562 on the second rib 56E side toward the straight portion W1 of the charged wire 52A.

[0067] In the above embodiment, the boss is configured to fit inside the coil portion, but the present invention is not limited to this. The boss may be inserted into the coil portion with a gap between the outer circumferential surface of the boss and the inner circumferential surface of the coil portion.

[0068] The torsion spring does not have to have a charging electrode. For example, the charging electrode may be a separate member from the torsion spring. In this case, electricity supplied to the charging electrode may be supplied to the charging wire via the torsion spring.

[0069] In the above embodiment, the cover is made of insulating resin, but it is sufficient that at least the rib is made of insulating resin. For example, the rib may be made of insulating resin and the other parts of the cover may be made of another insulating material.

[0070] The elements described in the above-mentioned embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0071] 50 Drum Cartridge 51 Photoconductor drum 52A Charged Wire 54 Torsion spring 54A Coil section 55 Drum Frame 55A Boss X1 Drum shaft X2 axis

Claims

1. a photosensitive drum rotatable about a drum axis extending in a first direction; a charging wire for charging the photoconductor drum, the charging wire extending in the first direction; a torsion spring that pulls the charging wire, the torsion spring having a coil portion centered on an axis along a second direction that intersects with the first direction; A drum frame; The outer diameter of the coil portion is greater than the length of the coil portion in the second direction, The drum frame has a boss extending in a second direction and inserted into the coil portion, the charging wire has a straight portion extending in the first direction, The drum cartridge according to claim 1, wherein the boss overlaps with the straight portion in the first direction.

2. 2. The drum cartridge according to claim 1, wherein an outer diameter of the coil portion is 1.5 times or more the length of the coil portion in the second direction.

3. 3. The drum cartridge according to claim 1, wherein the second direction is perpendicular to the first direction.

4. 3. The drum cartridge according to claim 2, wherein an outer diameter of the coil portion is three times or more the length of the coil portion in the second direction.

5. 5. The drum cartridge according to claim 4, wherein an outer diameter of the coil portion is at least five times the length of the coil portion in the second direction.

6. 6. The drum cartridge according to claim 1, wherein the boss holds the coil portion.

7. the drum cartridge is detachably attached to a main body housing having a main body electrode; 7. The drum cartridge according to claim 1, wherein the torsion spring has a charging electrode that contacts the main body electrode.

8. a cover that covers the torsion spring from the second direction, 8. The drum cartridge according to claim 1, wherein the cover has an arc-shaped rib that extends along an outer periphery of the coil portion.

9. 9. The drum cartridge according to claim 8, wherein the rib is made of an insulating resin.

10. 10. The drum cartridge according to claim 9, wherein the cover is made of an insulating resin.

11. 11. The drum cartridge according to claim 1, wherein the number of turns of the coil portion is 3 or less.

12. 12. The drum cartridge according to claim 11, wherein the number of turns of the coil portion is two or less.

13. 13. The drum cartridge according to claim 1, wherein the torsion spring is connected to one end of the charging wire in the first direction.

14. 14. The drum cartridge according to claim 1, wherein the torsion spring pulls the charging wire in a direction different from the first direction.

15. a photosensitive drum rotatable about a drum axis extending in a first direction; a charging wire for charging the photoconductor drum, the charging wire extending in the first direction; a torsion spring that pulls the charging wire, the torsion spring having a coil portion centered on an axis along a second direction that intersects with the first direction; Drum frame and a cover that covers the torsion spring from the second direction, The outer diameter of the coil portion is greater than the length of the coil portion in the second direction, The drum frame has a boss extending in a second direction and inserted into the coil portion, The drum cartridge according to claim 1, wherein the cover has an arc-shaped rib that extends along an outer periphery of the coil portion.

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