JP7613136B2 - Drum Cartridge - Google Patents

Description

This disclosure relates to a drum cartridge equipped with a charged wire.

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 that is 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.

JP 2006-039139 A

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.
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 smaller.

Therefore, the present disclosure aims to prevent the drum cartridge from becoming larger in the second direction while preventing the biasing force pulling the charged wire of the torsion spring from becoming smaller.

In order to solve the above-mentioned problem, 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.

With this configuration, by making the outer diameter of the coil section longer than the length of the coil section in the second direction, it is possible to prevent the drum cartridge from becoming larger in the second direction and to ensure the biasing force that pulls the charging wire. In addition, because the drum frame has a boss that fits into the coil section, the boss can prevent the torsion spring from shifting out of position.

Furthermore, the outer diameter of the coil portion may be 1.5 times or more the length of the coil portion in the second direction.

The second direction may also be perpendicular to the first direction.

Furthermore, the outer diameter of the coil portion may be three times or more the length of the coil portion in the second direction.

Furthermore, the outer diameter of the coil portion may be 5 times or more the length of the coil portion in the second direction.

The boss may also hold the coil portion.

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

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 that contacts the main body electrode.

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

With 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 section.

The ribs may also be made of insulating resin.

The cover may also be made of insulating resin.

The number of turns of the coil portion may be three or less.

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

The torsion spring may also be connected to one end of the charged wire in the first direction.

The torsion spring may also be configured to pull the charged wire in a direction different from the first direction.

This disclosure makes it possible to prevent the drum cartridge from becoming larger in the direction perpendicular to the charging wire.

1 is a cross-sectional view showing a color printer including a drum cartridge according to an embodiment of the present disclosure. 1A is a perspective view showing the structure around a torsion spring, and FIG. 1B is a perspective view showing the state in which a cover is attached to a drum frame. FIG. FIG. 4 is a cross-sectional view showing the structure around the torsion spring. FIG. FIG. 4 is a plan view showing a part of the cover in section. 13A and 13B are a perspective view and a plan view showing a modified example of the first rib.

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.

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 (described later) can pass. The upper cover 11 is a cover for opening and closing the opening 10A. The top surface of the upper cover 11 is an ejection tray 11A into which the sheet S ejected from the main body housing 10 is ejected. The upper cover 11 has an LED mounting member 11B that holds the LED unit 31.

The sheet supply unit 20 includes a supply tray 21 and a sheet transport roller 22. The supply tray 21 stores the sheet S. The sheet transport roller 22 transports the sheet S from the supply tray 21 toward the photosensitive drum 51.

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

The LED unit 31 has multiple LEDs (not shown) that expose the photoconductor drum 51. The LED unit 31 is rotatably connected to the LED mounting member 11B.

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 cartridges 40 include a drum cartridge 50 and a developing cartridge 60. The drum cartridge 50 is detachable from the main body housing 10. The drum cartridge 50 includes a photosensitive drum 51, a charger 52, and a cleaning roller 53.

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.

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.

The developing cartridge 60 is detachable from the drum cartridge 50. The developing cartridge 60 is configured with a developing roller 61, a supply roller 62, and a toner storage chamber 63.

The developing roller 61 is a roller that supplies toner to the photosensitive drum 51. The supply roller 62 is a roller that supplies toner to the developing roller 61.

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.

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.

In the image forming unit 30, the charger 52 charges the surface of the photoconductor drum 51. Then, the LED unit 31 exposes the surface of the photoconductor drum 51 to light. This forms an electrostatic latent image on the photoconductor drum 51.

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 photoconductor drum 51. This forms a toner image on the photoconductor drum 51.

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. The sheet S then passes between the heating roller 81 and the pressure roller 82. At this time, the toner image transferred to the sheet S is thermally fixed onto the sheet S.

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

As shown in Figs. 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, metal. The drum frame 55 is made of, for example, non-conductive resin. The cover 56 is made of, for example, insulating resin.

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

The coil portion 54A is a coil portion centered on an axis X2 along a second direction that intersects with 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.

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

As shown in FIG. 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.

The number of turns of the coil portion 54A should be 3 turns or less, and preferably 2 turns or less. Here, the number of turns refers to the number of turns of the coil portion 54A when it is fitted into the boss 55A of the drum frame 55.

As shown in FIG. 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.

2(a) and (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 the 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 the development 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 the development 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 development 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.

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.

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 located near the conductive spring 57 of the second drum cartridge 50Y when the first drum cartridge 50X and the second drum cartridge 50Y are attached to the main body housing 10. As a result, it is 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.

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 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.

As shown in FIG. 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.

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 that intersects with the first and second directions. Preferably, the third direction is perpendicular to the first and second directions. In this embodiment, the third direction is perpendicular to the first and second directions.

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 arranged at one end of the charged wire 52A in the first direction and at the other end of the charged wire 52A in the first direction. In more 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.

The charged wire 52A has a straight portion W1 extending in the first direction and an inclined portion W2 inclined relative 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.

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.

The inclined portion W2 has a ring-shaped ring portion W21 into which a portion 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.

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.

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.

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.

Because the cover 56 has the first rib 56D and the second rib 56E, the insulation distance between the conductive spring 57Y of the second drum cartridge 50Y, which is adjacent to the outside of the cover 56, and the coil portion 54A of the first drum cartridge 50X can be increased.

This disclosure is not limited to the above-described embodiments, but can be used in various forms, as exemplified below.

In the above embodiment, the first rib 56D that covers 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 to this. The length of the arc-shaped rib in the circumferential direction of the coil portion can be set arbitrarily. For example, as shown in Figures 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 that covers approximately 1/4 of the outer circumference of the coil portion 54A. Specifically, in the second embodiment shown in Figure 7, the drum cartridge 50 has a first rib 56F that is different from the above embodiment.

The first rib 56F has an arc rib 561 and a first linear rib 562, a second linear rib 563, and a third linear 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.

The arc rib 562 is located on the opposite side of the first linear rib 562 from the charged wire 52A in the first direction. 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.

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

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 inside the coil portion with a gap between the outer peripheral surface of the boss and the inner peripheral surface of the coil portion.

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

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

The elements described in the above embodiments and variations may be combined in any manner.

50 Drum cartridge 51 Photoconductor drum 52A Charging wire 54 Torsion spring 54A Coil portion 55 Drum frame 55A Boss X1 Drum shaft X2 Shaft

Claims (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;
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 . The drum cartridge according to claim 1, characterized in that the outer diameter of the coil portion is 1.5 times or more the length of the coil portion in the second direction. The drum cartridge according to claim 1 or 2, characterized in that the second direction is perpendicular to the first direction. The drum cartridge according to claim 2, characterized in that the outer diameter of the coil portion is at least three times the length of the coil portion in the second direction. The drum cartridge according to claim 4, characterized in that the outer diameter of the coil portion is at least five times the length of the coil portion in the second direction. The drum cartridge according to any one of claims 1 to 5, characterized in that the boss holds the coil portion. 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. 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. The drum cartridge according to claim 8 , wherein the rib is made of an insulating resin. 10. The drum cartridge according to claim 9 , wherein the cover is made of an insulating resin. 11. The drum cartridge according to claim 1, wherein the number of turns of the coil portion is 3 or less. 12. The drum cartridge according to claim 11 , wherein the number of turns of the coil portion is two or less. 3. The drum cartridge according to claim 1, wherein the torsion spring is connected to one end of the charging wire in the first direction. The drum cartridge according to claim 1 , wherein the torsion spring pulls the charging wire in a direction different from the first direction. 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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