JPH11249529A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing damage on a photoreceptor surface by parting a main charger and a transfer charger from the photoreceptor drum with a simple constitution, at the time of attaching/detaching the photoreceptor drum with respect to the device main body. SOLUTION: This image forming device is, provided with the photoreceptor drum unit 81 freely attachable/detachable to/from the device main body, equipping the photoreceptor drum 30 on a periphery of which an electrostatic latent image is formed, a main charger main body 71 electrifying the periphery of the photoreceptor drum 30, and a transfer charger main body 82 transferring the toner image on the photoreceptor drum 30 surface visualized by the developing device on a transported paper sheet. In this case, the device is constituted so that the main charger main body 71 and the transfer charger main body 82 are shiftable between the setting position where both the bodies approach the photoreceptor drum 30, and the retreating position where they part from the photoreceptor drum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a main charger for charging a photosensitive drum and a transfer charger, wherein the photosensitive drum is detachable from an apparatus main body. About.

[0002]

2. Description of the Related Art In image forming apparatuses such as copiers, printers, and facsimile machines, the surface of a photosensitive drum is charged by a main charger, and an electrostatic latent image is formed on the surface of the photosensitive drum based on a read document image. I do. The electrostatic latent image formed on the surface of the photosensitive drum is visualized into a toner image by a developing device. A transfer charger is provided near the photoconductor drum, and transfers a toner image to a sheet conveyed between the photoconductor drum and the transfer device. The toner image transferred onto the sheet is heated and melt-fixed by the fixing unit.

In such an image forming apparatus, a photosensitive drum unit including a photosensitive drum is detachable from a main body of the apparatus, and the photosensitive drum is replaced as necessary.

[0004]

The transfer charger is mounted on, for example, an opening / closing frame provided to be openable and closable with respect to the apparatus, and is separated from the photosensitive drum by opening the opening / closing frame. It is configured as follows. Further, the photosensitive drum unit is movable in a direction away from the main charger, and when the photosensitive drum unit is attached to or detached from the apparatus main body, the opening and closing frame is opened to separate the transfer charger from the photosensitive drum, The work is performed while the photosensitive drum unit is moved in a direction in which the photosensitive drum unit is separated from the main charger.

In this case, since the rotation center of the photosensitive drum is configured to move, it is difficult to maintain high positioning accuracy of the photosensitive drum. Further, a space for moving the photosensitive drum unit is required in the apparatus main body, and a complicated mechanism for moving the photosensitive drum unit is required. SUMMARY OF THE INVENTION It is an object of the present invention to prevent damage to the surface of a photoconductor drum by detaching a main charger and a transfer charger from the photoconductor drum with a simple configuration when a photoconductor drum unit is attached to and detached from an apparatus main body. An object of the present invention is to provide an image forming apparatus.

[0006]

According to the present invention, there is provided an image forming apparatus comprising: a photosensitive drum unit having a photosensitive drum on which an electrostatic latent image is formed on a peripheral surface thereof; A main charger for charging the peripheral surface of the photosensitive drum, a developing device for developing an electrostatic latent image formed on the surface of the photosensitive drum into a toner image, and a toner image on the surface of the photosensitive drum developed by the developing device. An image forming apparatus including a transfer charger that transfers a sheet to a conveyed sheet, wherein a main charger and a transfer charger are respectively located between a setting position close to the photosensitive drum and a retreat position separated from the photosensitive drum. It is configured to be movable.

In this case, when the photosensitive drum unit is attached to and detached from the apparatus main body, the main charger and the transfer charger are located at the respective retracted positions, so that the work can be performed without damaging the photosensitive drum surface. Since the rotation center of the photosensitive drum is constant, the positional accuracy of the photosensitive drum can be maintained high. Here, when the photoconductor drum unit is removed from the apparatus main body, the main charger is moved in a direction away from the peripheral surface of the photoconductor drum and locked at the retreat position, and when the photoconductor drum is mounted on the apparatus main body, It can be configured to move in a direction approaching the peripheral surface of the body drum and be locked at the setting position.

The main charger includes a main charger main body, a setting position at which the main charger main body is close to the peripheral surface of the photoreceptor drum, and a predetermined distance in a direction away from the apparatus main body of the photoreceptor drum unit from the setting position. A guide member for guiding between a retreat position separated by a predetermined distance in a direction away from the drum, an urging means for urging the main charger main body in a direction of detaching from the apparatus main body of the photosensitive drum unit, and a main charger main body An engaging member that engages with the photosensitive drum unit, wherein the engaging member engages with the photosensitive drum unit when the photosensitive drum unit is mounted on the apparatus main body when the main charger body is in the retracted position. The main charger body to the setting position, and Tsu bets is configured engaging member when the main charger body is moved while being guided by the guide member to the retracted position from the setting position when it is detached from the apparatus main body is separated from the photosensitive drum unit.

In this case, when the photosensitive drum unit is mounted on the apparatus main body, the main charger is automatically positioned at the setting position close to the photosensitive drum, and simultaneously when the photosensitive drum unit is detached from the apparatus main body. The main charger can be located at the retracted position. In addition, the transfer charger has a casing that is biased toward the photosensitive drum unit, and when the photosensitive drum unit is attached to and detached from the apparatus main body, the transfer charger contacts the casing of the transfer charger and presses the transfer charger away from the photosensitive drum. Can be configured. Specifically, a projection is provided on the side of the transfer charger side of the photosensitive drum unit that can press the casing of the transfer charger. When the photosensitive drum unit is attached to the apparatus main body, the projection slides on the casing while the transfer charger slides. Can be configured to be pressed in a direction away from the photosensitive drum. In this case, the transfer charger can be automatically set to the standby position when the photosensitive drum unit is attached or detached.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Overall Configuration] FIG. 1 is a cross-sectional view of a copying machine to which an embodiment of the present invention is applied. The copying machine 1 has a main body 10 and a document holder 11 mounted on the upper part of the main body 10 so as to be openable and closable.

An original platen 15 on which an original is placed is disposed on the main body 10 at an upper portion thereof. Inside the main body 10, an image forming unit 16 is provided at the left end as viewed from the front and substantially at the center in the vertical direction. Further, a paper feed cassette 17 for storing paper is detachably provided at a lower portion, and a bypass paper feed section 18 is provided on the left side thereof. An optical system 19 for reading image information of a document placed on the document table 15 is provided below the document table 15. A fixing device 20 for fixing an image on a sheet is provided diagonally above the left side of the image forming unit 16, and a discharge roller 21 is further provided diagonally above the left side thereof. In addition, on the outside of the main body of the discharge roller 21,
A discharge tray (not shown) is provided.
A bypass tray (not shown) is provided on the outside of the main body.

Paper feed cassette 17 and bypass paper feed section 18
A vertical transport path 25 that transports the supplied paper vertically toward the image forming unit 16 is provided between the image forming unit 16 and the image forming unit 16. Further, the image forming unit 16 and the discharge roller 21
A diagonal transport path 26 for transporting and discharging the sheet on which an image is formed diagonally upward is provided between them. [Image Forming Unit] The image forming unit 16 includes a photosensitive drum 30 on which an electrostatic latent image is formed as shown in FIG.
And a main charging device 31, a blank lamp 32, a developing device 33, a transfer device 34, and a cleaning device 35 disposed around the photosensitive drum 30.

The main charging device 31 is a device for charging the surface of the photosensitive drum 30, and is disposed diagonally above and to the left of the photosensitive drum 30. In addition, blank lamp 3
Reference numeral 2 denotes a lamp for neutralizing a desired area on the surface of the photosensitive drum 30 and is disposed adjacent to the right side of the main charging device 31. A developing device 33 for forming a toner image on the photosensitive drum 30 is disposed diagonally below and to the right of the photosensitive drum 30 with a predetermined gap from the blank lamp 32. The transfer device 34 is a device for transferring the toner image on the photosensitive drum 30 to paper,
The photosensitive drum 30 is disposed diagonally below and to the left of the photosensitive drum 30. The downstream side of the vertical transport path 25 is located between the transfer device 34 and the developing device 33. The cleaning device 35 is a device for removing residual toner and the like on the surface of the photosensitive drum 30, and is disposed diagonally above and to the left of the photosensitive drum 30.

As shown in FIG. 1, a toner cartridge 36 for storing replenishment toner is provided above the developing device 33. [Sheet Feeding Unit] The sheet feeding cassette 17 is provided such that the end on the paper outlet side is located on the left side of the apparatus and on the right side of the vertical transport path 25, and the other end is located on the right side of the apparatus. Extending. A feed roller 37 for sending out the paper in the cassette to the vertical transport path 25 is provided above the end on the paper outlet side. The bypass paper feed unit 18 is for manually feeding paper from the lower left side of the apparatus, or supplying paper placed on a bypass tray to the image forming unit 16.
It is continuous with the vertical transport path 25.

[Optical System] The optical system 19 includes a lamp unit 40 having a light source and a reflector, a mirror unit 41,
42, a lens unit 43, and a reflection mirror 44. The light from the reflection mirror 44 passes between the blank lamp 32 and the developing device 33 and irradiates the photosensitive drum 30.

[Conveying Path] As shown in FIG. 2, the vertical conveying path 25 includes a first conveying roller pair 50, a second conveying roller pair 51 disposed above the first conveying roller pair 50, and Guide member 5 disposed before and after transport roller pair 50, 51
And 3. And, this vertical transport path 25 is
As schematically shown in FIG. 1, a first transport unit 25a formed to extend diagonally upward and to the left between the paper feed cassette 17 and the first transport roller pair 50, a first transport roller pair 50, and a second transport unit. A second transport unit 25b is formed to extend diagonally upward to the right between the roller pair 51, and extends diagonally upward to the left between the second transport roller pair 51 and the image forming unit 16 (photosensitive drum 30). And a third transport unit 25c formed as described above,
It extends vertically as a whole.

As shown in FIG. 2, the oblique transport path 26 has a guide member 5 formed by a part of the open / close frame 55.
5a, a guide member 20a formed by a part of the frame of the fixing unit 20, and a guide member 56 provided between the fixing unit 20 and the discharge roller 21. As shown in FIG. 2, the opening / closing frame 55 is supported rotatably about the support shaft 54 with respect to the main body frame. The transfer device 34, the left roller 50a of the first transport roller pair 50, the left roller 51a of the second transport roller pair 51, and the left member of the guide member 53 are mounted on the opening / closing frame 55, respectively. ing. Therefore, by opening and closing the opening and closing frame 55, these members can be set on the copying machine main body or separated.

Incidentally, as shown in FIG.
A cover 57 is provided to be freely opened and closed outside the
By opening the cover 57, the fixing unit 20 and the discharge roller 21 can be exposed. [Fixing Unit] The fixing unit 20 includes a heating roller 61 and a pressure roller 62 that can be pressed against the heating roller 61. The heating roller 61 has a fixing heater 63 built therein.
The periphery is covered by the upper fixing housing 64.
On the paper discharge side of the upper fixing housing 64, a peeling claw 65 that is rotatably supported is disposed. This peeling claw 65
The tip is heated roller 6 by a torsion spring (not shown).
1 is urged so as to be pressed against the peripheral surface. The peeling claw 65 allows the paper to be wound around the heating roller 61 to be peeled and conveyed to the paper discharge side.

The pressure roller 62 has a shaft 67 having a bearing 68.
And is supported by the lower fixing housing 66 via a spring 69. The bearing 68 is vertically movable with respect to the lower fixing housing 66, and is constantly urged toward the heating roller 61 by a spring 69. The bearing 68 and the spring 69 are arranged at both ends in the axial direction of the roller.

[Main Charger] Main Charger 3
1 has a main charger main body 71 in which a discharge wire for charging the photosensitive drum 30 by performing corona discharge is stretched. The main charger main body 71 has guided portions 73 and 74 projecting from the side opposite to the photosensitive drum 30. A guide member 72 is arranged on a side of the main charger 71 opposite to the photosensitive drum 30. The guide member 72 is connected to the guided portion 7 of the main charger main body 71.
Guide grooves 75 and 76 for guiding the members 3 and 74 are provided. The guide grooves 75 and 76 are provided in the length direction of the main charger 71, bulge toward the photosensitive drum 30 at a predetermined position, and have leaf springs 77 and 78 attached at this position.

When the guided portions 73 and 74 are located at the bulging portions of the guide grooves 75 and 76, the guided portions 73 and 74 abut against the leaf springs 77 and 78 and are urged toward the photosensitive drum 30. When the guided portions 73 and 74 are separated from the bulging portions of the guide grooves 75 and 76, the photosensitive drum 3 is released from the urging force of the leaf springs 77 and 78 and is guided by the guide grooves 75 and 76.
Move in the direction away from zero.

The main charger body 71 is urged by a spring 80 rightward in FIG. Further, the main charger main body 71 has an engaging portion 79 on the right end side in FIG. 5 that can abut on the abutting portion 82 of the photosensitive drum unit 81. When the photosensitive drum unit 81 is mounted on the apparatus main body, the abutting portion 82 abuts on the engaging portion 79 of the main charger main body 71, and the main charger main body 71 is moved to the right against the urging force of the spring 80. (See FIG. 5). At this time, the main charger body 7
The first guided portions 73 and 74 are provided in the guide grooves 7 of the guide member 72.
5 and 76, and leaf springs 77 and 78
Is biased toward the photosensitive drum 30 side.
Thus, the main charger main body 71 is at the setting position close to the photosensitive drum 30.

When the photosensitive drum unit 81 is to be detached from the apparatus main body, the photosensitive drum unit 81 is pulled out from the front of the apparatus main body. When the photoconductor drum unit 81 is pulled out from the apparatus main body, the main charger main body 71 moves in the same direction as the photoconductor drum unit 81 by the urging force of the spring 80. At this time, the guided portions 73 and 74 are separated from the leaf springs 77 and 78, and move to the right ends of the guide grooves 75 and 76 in FIG. Here, the guided parts 73 and 74 are restricted from moving in the guide grooves 75 and 76, and the movement in the length direction of the main charger main body 71 is restricted. At the same time, the main charger main body 71 is separated from the photosensitive drum 30 to be in a predetermined retreat position (see FIGS. 6 and 7). When the photosensitive drum unit 81 is further pulled out in this state, the contact portion 82 is disengaged from the engaging portion 79 of the main charger main body 71, and only the photosensitive drum unit 81 can be pulled out from the apparatus main body.

When the photosensitive drum unit 81 is removed, the main charger main body 71 is in a retracted position as shown in FIG. When the photosensitive drum unit 81 is mounted on the apparatus main body, when the photosensitive drum main body 81 is inserted to a position as shown in FIG. 7, the contact portion 82 comes into contact with the engaging portion 79 of the main charger main body 71. As the rear photosensitive drum unit 81 moves, the main charger main body 71 is moved against the urging force of the spring 80 as shown in FIG.
Move left. Guided portions 73 and 74 are provided with guide grooves 75,
When the bulging portion 76 is reached, it comes into contact with the leaf springs 77 and 78 and is urged toward the photosensitive drum 30. Thereby, as shown in FIG. 5, the main charger main body 71 is positioned at the setting position close to the photosensitive drum 30 side.

Therefore, when the photosensitive drum unit 81 is attached or detached, the main charger main body 71 is automatically placed in the retracted position, so that the surface of the photosensitive drum 30 is not damaged. [Transfer Charger] The transfer device 34 has a transfer charger main body 82 in which a discharge wire for transferring a toner image to a sheet by performing corona discharge is stretched. The transfer charger main body 82 is attached to the guide member 55a. The guide member 55a is supported by a support shaft 84 and is rotatable with respect to the opening / closing frame 55. The transfer charger main body 82 is rotatable with respect to the opening / closing frame 55 together with the guide member 55a.
3 urges the photosensitive drum 30 in a direction approaching the photosensitive drum 30. The upper end surface of the transfer charger main body 82 forms a contact surface that comes into contact with the outer wall of the photosensitive drum unit 81, and the transfer charger main body 82 is positioned by the contact surface contacting the photosensitive drum unit 81.

The guide member 55a has a guide groove 85 as shown in FIG. 8 at the tip of the photosensitive drum unit 81 in the mounting direction. The guide groove 85 is provided for the guide member 55.
a has a curved surface that is smoothly continuous with the side wall portion 86. A protrusion 87 corresponding to the guide groove 85 of the guide member 55a is provided on a side wall of the photosensitive drum unit 81 on the opening / closing frame 55 side. The projection 87 is set so as to be located in the guide groove 85 of the guide member 55a when the photosensitive drum unit 81 is set at a predetermined position in the apparatus main body.

When the photosensitive drum unit 81 is set at a predetermined position in the apparatus main body, the projection 87 is located in the guide groove 85 of the guide member 55a, and as shown in FIG. The setting position is close to the photosensitive drum 30 by the urging force of the spring 83. When the photosensitive drum unit 81 is pulled out of the apparatus main body, the protrusion 87 is guided by the curved surface of the guide groove 85 and rides on the side wall 86 of the guide member 55a. At this time, the projection 87 presses the guide member 55a in a direction away from the photosensitive drum unit 81 to rotate the guide member 55a together with the transfer charger main body 82. Accordingly, the transfer charger main body 82 moves against the urging force of the spring 83, as shown in FIG.
It is located at a retracted position separated from the photosensitive drum 30. When the photosensitive drum unit 81 is further pulled out and the projection 87 is separated from the side wall 86 of the guide member 55a, the guide member 55a and the transfer charger main body 82 are moved toward the photosensitive drum 30 by the urging force of the spring 83. At this time, the photosensitive drum unit 81 is substantially separated from the apparatus main body, and the transfer charger main body 82 does not come into contact with the photosensitive drum 30. The rotation position of the guide member 55a is regulated by a regulating member (not shown), and even when the photosensitive drum unit 81 is detached from the apparatus main body, the guide member 55a and the transfer charger main body 82 exceed the predetermined position and the photosensitive member It does not move in the direction of the drum 30.

When the photosensitive drum unit 81 is mounted on the apparatus main body, the photosensitive drum unit 81 is inserted from the front of the apparatus main body. When the photosensitive drum unit 81 is inserted into the apparatus main body, the projection 87 comes into contact with the side wall 86 of the guide member 55a to press the guide member 55a and rotate the guide member 55a away from the photosensitive drum unit 81. As a result, the transfer charger main body 82 moves integrally with the guide member 55a in a direction away from the photosensitive drum 30 (see FIG. 6).

When the photosensitive drum unit 81 is further inserted and the projection 87 is located in the guide groove 85 of the guide member 55a, the guide member 55a is released from the pressing force of the projection 87. As a result, the transfer charger main body 82 and the guide member 55a are rotated toward the photosensitive drum 30 by the biasing force of the spring 83, and the transfer charger main body 8 is moved.
Positioning is performed when the contact surface on the upper surface of the second member 2 contacts the outer wall surface of the photosensitive drum unit 81 (see FIG. 4). In this state, the photosensitive drum unit 81 is set at a predetermined position of the apparatus main body.

As described above, when the photosensitive drum unit 81 is attached or detached, the projection 87 presses the guide member 55a to rotate in a direction away from the photosensitive drum unit 81, and at the same time, moves the transfer charger main body 82 to the photosensitive drum 30.
Move in the direction away from. Therefore, when the photosensitive drum unit 81 is attached or detached, the transfer charger body 8
Reference numeral 2 denotes a retreat position which is separated from the photosensitive drum 30, so that the surface of the photosensitive drum is not damaged.

[Other Embodiments] (A) The main charger main body 71 and the transfer charger main body 82 are locked at a setting position close to the photosensitive drum 30 and a retracted position separated from the photosensitive drum 30. It is also possible to provide a mechanism so that when the photosensitive drum unit 81 is attached or detached, the main charger main body 71 and the transfer charger main body 82 are manually positioned at the retracted position.

[0032]

In the image forming apparatus according to the present invention, when the photosensitive drum unit is attached to and detached from the apparatus main body, the main charger and the transfer charger are located at the retracted positions separated from the photosensitive drum. No damage to the drum surface. Further, since the axial center of the photosensitive drum is not moved, there is no need to provide a space for moving the photosensitive drum unit inside the apparatus main body without impairing the positioning accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a copier employing a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part thereof.

FIG. 3 is a schematic diagram of the paper transport path.

FIG. 4 is a vertical sectional view of a photosensitive drum unit and a transfer device.

FIG. 5 is a plan view of a main charger.

FIG. 6 is a longitudinal sectional view of a photosensitive drum unit and a transfer device.

FIG. 7 is a plan view of a main charger.

FIG. 8 is a perspective view for explaining a main part of a guide member.

FIG. 9 is a perspective view for explaining a main part of the photosensitive drum unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 copier 10 apparatus main body 11 document holder 15 document table 16 image forming unit 17 paper feed cassette 18 bypass paper feed unit 20 fixing unit 30 photoconductor drum 31 main charging device 34 transfer device 55 opening / closing frame 55a guide member 71 main charger main body 72 Guide member 73 Guided part 74 Guided part 75 Guide groove 76 Guide groove 77 Leaf spring 78 Leaf spring 79 Engagement part 80 Spring 81 Photoconductor drum unit 83 Spring 85 Guide groove 86 Side wall part 87 Projection

Claims (5)

[Claims] A photosensitive drum unit having a photosensitive drum having an electrostatic latent image formed on a peripheral surface thereof and being detachably mountable to an apparatus body; a main charger for charging a peripheral surface of the photosensitive drum; A developing device for developing an electrostatic latent image formed on the surface of the drum into a toner image, and a transfer charger for transferring the toner image on the surface of the photosensitive drum developed by the developing device to a sheet of paper conveyed An image forming apparatus comprising: an image forming apparatus, wherein the main charger and the transfer charger are each movable between a setting position close to the photosensitive drum and a retreat position separated from the photosensitive drum. apparatus. 2. The main charger moves in a direction away from the peripheral surface of the photosensitive drum when the photosensitive drum unit is detached from the apparatus main body, and is locked at the retreat position. The image forming apparatus according to claim 1, wherein when mounted on the image forming apparatus, the image forming apparatus moves in a direction approaching a peripheral surface of the photosensitive drum and is locked at the setting position. 3. The main charger includes: a main charger main body; a setting position at which the main charger main body is close to a peripheral surface of the photoconductor drum; and a predetermined distance in a direction away from the apparatus main body of the photoconductor drum unit from the setting position. A guide member that guides the main charger main body from a retreat position separated by a predetermined distance in a direction away from the photoconductor drum, and a biasing device that urges the main charger main body in a direction in which the main charger main body is separated from the apparatus main body of the photoconductor drum unit. Means, and an engaging member provided on the main charger main body and engaging with the photoconductive drum unit, wherein the photoconductive drum unit is mounted on the apparatus main body when the main charger main body is at a retracted position. When the engagement member engages with the photosensitive drum unit, When the main charger main body is guided by the guide member from the setting position to the retreat position when the photosensitive drum unit is detached from the apparatus main body, the engaging member is positioned at the setting position. Is configured to be detached from the photosensitive drum unit.
An image forming apparatus according to claim 1. 4. The transfer charger has a casing which is biased toward the photosensitive drum unit, and the photosensitive drum unit contacts the casing of the transfer charger when the photosensitive drum unit is attached to and detached from the apparatus main body, and transfers the transfer charger. The pressing in a direction away from the photosensitive drum,
3. The image forming apparatus according to any one of 3. 5. A photosensitive drum unit having a projection on a side surface on a transfer charger side, the projection being capable of pressing a casing of the transfer charger, wherein the projection slides on the casing when the photosensitive drum unit is attached to an apparatus main body. The image forming apparatus according to claim 4, wherein the transfer charger is pressed in a direction away from the photosensitive drum while moving.