JP5347751B2 - Image forming cartridge - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming cartridge, and more particularly to an image forming cartridge including a photosensitive member serving as a core for forming an image by electrophotography.

  In an image forming apparatus such as a copying machine or a printer that forms an image by electrophotography, an image forming cartridge in which a photosensitive member, a developing unit, a charger, and the like are integrated is detachably provided in the apparatus main body. In these image forming cartridges, the charging roller and the cleaning roller are in pressure contact with the photosensitive member at a predetermined pressure, and when held in the pressure contact state for a long time, creep or bleed occurs on the roller. In many cases, these problems occur in a period from when the apparatus is assembled and inspected until it is operated under the user.

  Conventionally, for example, in Patent Document 1, when a separation member is attached to a process cartridge, the separation member is supported at both ends by one frame body, and the other frame body is supported by a portion between them. A structure has been proposed in which a developing roller and a charging roller used in pressure contact with a drum are kept in a separated state.

  However, the press release mechanism described in Patent Document 1 is independent for each press contact portion, and a plurality of press release mechanisms are necessary and are structurally complicated. In addition, it is difficult to control the pressure contact state and the separation state. For example, the pressure contact state and the separation state cannot be controlled by a simple operation of pulling out the separation member.

JP 2006-308755 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming cartridge capable of pressing / releasing a roller with respect to a photosensitive member with a simple configuration and simple operation.

In order to achieve the above object, an image forming cartridge according to an aspect of the present invention includes:
A photosensitive member, a roller biased to press against the photosensitive member, a pair of bearings rotatably holding the roller, a spring member biasing the pair of bearings toward the photosensitive member, and the photosensitive member A body that supports the body, the bearing, and the spring member, a pressure release member that engages with the housing and the bearing, and that regulates the bearing at a position away from a position where the roller is pressed against the photoreceptor; With
Said pressure release member is pulling freely positioned relative to the housing, the engaging portion between the bearing has irregularities at a predetermined pitch in the withdrawal direction,
The unevenness formed on the pressure release member causes the roller to be pressed against the photoconductor when the concave portion is engaged with the bearing, and the roller is separated from the photoconductor when the convex portion is engaged with the bearing. Letting
It is characterized by.

  The target roller is, for example, a charging roller, a developing roller, or a cleaning roller.

In the image forming cartridge, the pressure release member has an uneven portion at a predetermined pitch at the engaging portion with the roller bearing. When the concave portion is engaged with the bearing, the roller is pressed against the photoconductor, and when the convex portion is engaged with the bearing, the roller is separated from the photoconductor. This operation can be performed by a simple operation of pulling out the pressure release member from the housing.

  According to the present invention, it comprises a simple configuration in which a press release member having irregularities that engage with a roller bearing is provided, and press contact / release is possible by a simple operation of pulling out the press release member at a predetermined pitch. It is possible to prevent the occurrence of creep or bleed on the roller.

1 is a schematic configuration diagram illustrating a printer including an image forming cartridge according to the present invention. FIG. 2 is a schematic explanatory diagram illustrating a photosensitive drum, a charging roller, and a pressure release member in the image forming cartridge. It is a perspective view which shows the said press-contact cancellation | release member. FIG. 2 is a perspective view illustrating a photosensitive drum, a charging roller, and a pressure release member in the image forming cartridge. FIG. 6 is an explanatory diagram showing a pressure roller pressing / releasing operation.

  Embodiments of an image forming cartridge according to the present invention will be described below with reference to the accompanying drawings. In addition, in each drawing, the same code | symbol is attached | subjected regarding the same member and part, and the overlapping description is abbreviate | omitted.

(Schematic configuration of image forming apparatus, see FIG. 1)
An image forming apparatus equipped with an image forming cartridge according to the present invention will be described with reference to FIG. This image forming apparatus is a tandem type color printer, and roughly includes an image forming cartridge 10 (10y, 10m, 10c, 10k) and a laser scanning unit for forming toner images of Y, M, C, and K colors. 20 and the intermediate transfer unit 30 as a center.

  Each of the image forming cartridges 10 includes a photosensitive drum 12, a charging roller 13, a developing unit 14, a cleaning roller 15 for residual toner and residual charge, and the like disposed in a housing indicated by a dotted line in FIG. Can be taken in and out of the apparatus main body in a direction perpendicular to the paper surface. In the image forming cartridge 10, the electrostatic latent image drawn on the photosensitive drum 12 by the laser irradiated from the laser scanning unit 20 is developed by the developing roller 14a to form a toner image.

  The intermediate transfer unit 30 includes an intermediate transfer belt 31 that is rotationally driven endlessly in the direction of arrow B, and an electric field applied from a transfer roller 32 facing each photoconductor drum 12 causes each photoconductor drum 12 to be placed on each photoconductor drum 12. The formed toner image is primarily transferred onto the intermediate transfer belt 31 and synthesized. Note that such an electrophotographic image forming process is well known, and a detailed description thereof will be omitted.

  An automatic paper feeding unit 40 that feeds recording sheets one by one is arranged at the lower part of the apparatus main body. The recording sheet passes from the paper feeding roller 41 through the timing roller 42 to the intermediate transfer belt 31 and the secondary transfer roller 35. The toner image (color composite image) is secondarily transferred here. Thereafter, the recording sheet is conveyed to the fixing unit 45 where the toner is heated and fixed, and is discharged to a tray portion 46 disposed on the upper surface of the apparatus main body.

  In the image forming cartridge 10, the charging roller 13 is made of a conductive elastic body, and shaft portions 13 a (see FIG. 4) at both ends are rotatably supported by bearings 16. The charging roller 13 is pressed against the photosensitive drum 12 with a predetermined pressure by the bearing 16 being biased toward the photosensitive drum 12 by the coil spring 17.

(Charging roller contact / separation mechanism, see FIGS. 2 to 5)
If the charging roller 13 is kept rotating and the pressure contact state with the photosensitive drum 12 is continued for a long period of time, problems such as creep and bleeding occur. Since the charging roller 13 is operated (rotated) on a daily basis after the apparatus is delivered to the user, such a problem does not occur. However, if it takes a long time for the device to be delivered to the user after being assembled and inspected at the factory, the above-described problem may occur.

  Accordingly, in this embodiment, the bearing 16 is attached to the housing 11 (see FIG. 4) of the cartridge 10 so as to be movable in the vertical direction, and is elastically biased toward the photosensitive drum 12 from below by the coil spring 17. At the same time, the pressure release member 50 was attached to be slidable in the attaching / detaching direction of the cartridge 10 (arrow A: pull-out direction, arrow A ′: insertion direction). The housing 11 rotatably supports the photosensitive drum 12 and also supports a bearing 16 and a coil spring 17.

  As shown in FIG. 3, the pressure release member 50 is formed of a long body having a circular gripping portion 51 at one end, and concave portions 52a, 52b and convex portions 53a, 53b, 53c are formed at a predetermined pitch in the longitudinal direction on the lower surface. p is formed. The pressure release member 50 is attached to the housing 11 in a state along the charging roller 13 when the cartridge 10 is assembled, and in the directions of arrows A and A ′ at the opening 11a of the housing 11 (see FIG. 4). Guided and movable.

  On the other hand, a protrusion 16a is formed on the bearing 16, and the protrusion 16a can be engaged with the concave portions 52a and 52b and the convex portions 53a, 53b, and 53c of the pressure release member 50. As shown in FIG. 2, the bearings 16 are disposed at both ends of the charging roller 13, and the concave portions 52 a and 52 b and the convex portions 53 a, 53 b, and 53 c are positioned to face the protrusions 16 a of the respective bearings 16.

  Next, the contact / separation operation of the charging roller 13 with respect to the photosensitive drum 12 by the pressure release member 50 will be described. When the pressure release member 50 is incorporated in the cartridge 10, the convex portion 53 a engages with the protrusion 16 a of the bearing 16 from above, and the bearing 16 moves slightly downward against the spring force of the coil spring 17. 13 is separated from the surface of the photosensitive drum 12 (see FIG. 5A).

  When the assembled cartridge 10 is tested at the factory (first test), the pressure release member 50 is pulled out in the direction of arrow A by 1 pitch p. As a result, the recess 52a faces the protrusion 16a, and the bearing 16 is urged by the coil spring 17 to move upward, so that the charging roller 13 comes into pressure contact with the photosensitive drum 12 with a predetermined pressure (FIG. 5 ( B)). When the first test is completed, the pressure release member 50 is further pulled out in the direction of arrow A by one pitch p. At this time, the convex portion 53 b engages with the protrusion 16 a and the charging roller 13 is separated from the surface of the photosensitive drum 12.

  Further, when the cartridge 10 is mounted on the printer and an image formation test (second test) is performed, the pressure release member 50 is further pulled out in the arrow A direction by 1 pitch p. As a result, the recess 52b faces the protrusion 16a, and the charging roller 13 comes into pressure contact with the photosensitive drum 12 again. When the second test is completed, the pressure release member 50 is further pulled out by one pitch p, the convex portion 53c is engaged with the projection 16a, and the charging roller 13 is separated from the surface of the photosensitive drum 12. In this state, the printer waits for shipment.

  When the printer is delivered to the user, the pressure release member 50 is completely pulled out from the cartridge 10. As a result, the charging roller 13 is maintained in a pressure contact state with the photosensitive drum 12 at a predetermined pressure.

  As described above, in this embodiment, the contact / separation mechanism of the charging roller 13 has a simple configuration in which the protrusion 16a is formed on the bearing 16 and the pressure release member 50 having the unevenness that engages with the protrusion 16a is provided. In addition, the charging roller 13 can be brought into pressure contact / release with the photosensitive drum 12 by a simple operation of pulling out the pressure release member 50 by a predetermined pitch p. This prevents a problem that creep or bleed occurs on the charging roller 13.

(Other examples)
The image forming cartridge according to the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the gist thereof.

  In particular, in the present invention, the member to be brought into contact with or separated from the photosensitive drum 12 is not limited to the charging roller 13 but may be the developing roller 14a or the cleaning roller 15. Further, the number of concave portions and convex portions formed on the pressure release member 50 is not limited to the above-described embodiment, and if the test at the factory is one time, or the two times are short in time. If it is done in, it will be less. Further, the pressure release member 50 may be mounted on the cartridge 10 as long as it is set so that the concave portion faces the protrusion 16a during operation by the user.

  As described above, the present invention is useful for an image forming cartridge, and is particularly excellent in that the roller can be pressed / released with respect to the photosensitive member with a simple configuration and a simple operation.

DESCRIPTION OF SYMBOLS 10 ... Image forming cartridge 11 ... Housing 12 ... Photosensitive drum 13 ... Charging roller 16 ... Bearing 16a ... Protrusion 17 ... Coil spring 50 ... Pressure contact release member 52a, 52b ... Concave part 53a, 53b, 53c ... Convex part

Claims (3)

A photosensitive member, a roller biased to press against the photosensitive member, a pair of bearings rotatably holding the roller, a spring member biasing the pair of bearings toward the photosensitive member, and the photosensitive member A body that supports the body, the bearing, and the spring member, a pressure release member that engages with the housing and the bearing, and that regulates the bearing at a position away from a position where the roller is pressed against the photoreceptor; With
Said pressure release member is pulling freely positioned relative to the housing, the engaging portion between the bearing has irregularities at a predetermined pitch in the withdrawal direction,
The unevenness formed on the pressure release member causes the roller to be pressed against the photoconductor when the concave portion is engaged with the bearing, and the roller is separated from the photoconductor when the convex portion is engaged with the bearing. Letting
An image forming cartridge characterized by the above.   The image forming cartridge according to claim 1, wherein the roller is at least one of a charging roller, a developing roller, and a cleaning roller. The image forming cartridge according to claim 1 or claim 2, wherein the convex and the concave are formed alternately at a predetermined pitch.

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