JP2531723B2 - Process cartridge and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic copying apparatus or an electrostatic recording apparatus. More specifically, at least an image carrier is built-in, has a process cartridge that is attachable to and detachable from the apparatus main body, and is provided with a protective cover that covers an exposed portion of the image carrier from the cartridge when the process cartridge is removed. It relates to the device.

[Conventional technology]

FIG. 4 is a vertical sectional view of an electrophotographic copying machine showing an example of a conventional image forming apparatus of this type.

In the figure, reference numeral 1 is an apparatus main body, 2 is a process cartridge detachably mounted in the main body 1, a photosensitive drum 3 as an image bearing member is provided in the cartridge 2, and not shown in the drawing. Known process devices such as a primary charger, a developing device, and a cleaner are built in.

The process cartridge 2 is configured such that a part (the lower surface side in the figure) of the photosensitive drum 3 is exposed, and the protective cover 4 that covers the exposed portion has a pair of swing arms 5 and 6.
It is attached to the cartridge 2 via the so as to be openable and closable.

The protective cover 4 has a screw coil spring 7 for constantly biasing the swing arm 5 counterclockwise in the drawing around the swing shaft 5a when the cartridge 2 is removed from the apparatus main body 1.
As a result, as shown in FIG. 5, the exposed portion of the photosensitive drum 3 is held in a state of being covered, and light from the outside is incident on the exposed portion to deteriorate the photoreceptor, or it is directly touched and soiled. Is being prevented.

Also, when setting the cartridge 2 in the apparatus main body 1,
The swing arm 5 is rotated in the clockwise direction in the figure from the state of FIG. 5 against the torsion coil spring 7 by a member (not shown) on the apparatus main body side that abuts on the cam surface 5b of the swing arm 5. As shown in FIG. 4, the cover 4 is held in a state of being retracted from the exposed portion of the photosensitive drum 3, and an image can be formed.

In FIG. 4, 8a and 8b are guides for manually feeding a sheet material such as transfer paper, and the sheet material manually fed into the guides 8a and 8b is fed by a pair of registration rollers 9a and 9b. It is fed between the photosensitive drum 3 and the transfer charger 11 along a pair of upper and lower transfer guides 10a and 10b. On the other hand, a toner image is formed on the surface of the photosensitive drum 3 according to a known electrophotographic process, and the toner image is sequentially transferred onto the sheet material by the transfer charger 11. The sheet material on which the image is transferred is subsequently sent to the fixing device 13 by the conveyor belt 12 and the like, the toner image on the sheet material is fixed, and the sheet material is discharged to the outside of the apparatus.

[Problems to be solved by the invention]

The conventional image forming apparatus has the above-described configuration, and the protective cover 4 of the photosensitive drum 3 performs the above-described functions such as light shielding when the process cartridge 2 is removed from the apparatus main body 1. Device body 1
In the state where the protective cover 4 is set to, the protective cover 4 is retracted and moved so as not to perform any function merely by mechanically retracting and moving so as not to hinder the transfer process or the sheet material conveying process. There is a problem that a space for storing and arranging the device inside is required in the main body of the device, which hinders downsizing of the device.

On the other hand, a guide member for guiding a sheet material such as a transfer paper, particularly a pair of upper and lower transfer guides 10 for guiding the sheet material from the registration rollers 9a and 9b between the photosensitive drum 3 and the transfer charger 11.
The shape and position accuracy of a and 10b have a great influence on the final image quality, so accurate positioning is required.

In this case, the arrangement position of the transfer guide is basically set by the distance from the center of the photosensitive drum that serves as a reference for image formation. However, in the above-mentioned conventional example, the transfer guide is arranged along with other sheet material conveying systems in the apparatus main body. On the other hand, since the photosensitive drum is disposed in the process cartridge that can be attached to and detached from the main body of the apparatus, the photosensitive drum is centered on the drum via at least two intermediate members of the process cartridge and the main body of the apparatus. Since the distance from the to the transfer guide is set, it is very difficult to ensure the positional accuracy.
That is, in order to make the process cartridge detachable and to keep the distance between the photosensitive drum and the transfer guide constant and to position and hold them at a predetermined position, usually about five intermediate members are required, and each intermediate member itself. It is extremely difficult to accurately set the distance between the photosensitive drum and the transfer guide because the errors of the component accuracy and the mounting accuracy are accumulated.

 The present invention aims to solve the above problems.

B. Structure of the Invention [Means for Solving Problems] The present invention includes a guide member for guiding the sheet material conveyance direction, and is attachable to and detachable from an image forming apparatus for forming an image on a sheet material. In the process cartridge,
A photoconductor, a process unit acting on the photoconductor, a protection position for protecting a transfer area of the photoconductor for transferring a toner image formed on the photoconductor to the sheet material, and a retreat from the protection position. And a protection cover that can take a retracted position, and the protection cover is provided on the upstream side of the transfer area with respect to the sheet material conveyance direction in accordance with the operation of mounting the process cartridge in the image forming apparatus. A protective cover driving means for retracting the protective cover to a retracted position facing the guide member, the protective cover being provided in the image forming apparatus on the upstream side of the transfer area with respect to the conveying direction of the sheet material. The process cartridge is configured to be retracted to a retracted position facing the guide member and also used as a sheet material conveyance guide.

Still another aspect of the present invention is an image forming apparatus for forming an image on a sheet material, wherein a process cartridge is attachable / detachable, and a, a photoconductor, a process unit acting on the photoconductor, and the photoconductor are formed on the photoconductor. A protective cover for protecting the transfer area of the photoconductor for transferring the toner image to the sheet material, and a retractable position for retracting from the protective position, and the process cartridge mounted on the image forming apparatus. A protective cover driving unit that retracts the protective cover to the retreat position that is on the upstream side of the transfer area in the sheet material conveyance direction and that faces the guide member. And retreat the protective cover to a retreat position upstream of the transfer region in the sheet material conveying direction and facing a guide member provided in the image forming apparatus. In addition, a mounting portion for removably mounting the process cartridge configured also as a conveyance guide for the sheet material, b, and protection protected by the retracted position of the process cartridge mounted in the mounting portion. It was installed to face the cover,
An image forming apparatus comprising: the guide member for guiding the sheet material conveyance direction.

[Work]

When the process cartridge is removed, the protective cover that covers the exposed part of the image carrier is also used as the sheet material conveyance guide when the process cartridge is installed, so that the protective cover is always used as a functional component, and the cartridge is installed as before. Sometimes, a space for simply accommodating and arranging the sheet in the main body of the apparatus is unnecessary without using any protective cover, and the sheet material conveying guide can be accurately arranged with respect to the image carrier in the process cartridge. .

〔Example〕

FIG. 1 is a vertical sectional front view of an electrophotographic copying machine showing an embodiment of the present invention, and FIG. 2 is a front view of a process cartridge removed from the apparatus main body, which is the same as FIGS. 4 and 5 above. The members having the function of are given the same reference numerals, and the description thereof will be omitted.

In the embodiments described below, at least an image carrier is built-in, and a process cartridge that can be attached to and detached from the apparatus main body is provided, and a protective cover that covers an exposed portion of the image carrier from the cartridge when the process cartridge is removed is provided. An image forming apparatus having the above-mentioned structure is characterized in that the protective cover is also used as a sheet material conveyance guide in the process cartridge apparatus.

In the illustrated example, the protective cover 4 of the photosensitive drum 3 is also used as one of the pair of upper and lower transfer guides 10a and 10b (upper guide 10a) in the conventional example.

When the process cartridge 2 is removed from the apparatus main body 1 as shown in FIG. 2, the protective cover 4 constantly urges the swing arm 5 about the swing shaft 5a in the clockwise direction in the figure. The screw coil spring 7 holds the exposed portion of the photosensitive drum 3 in the same manner as in the conventional example.

In the illustrated example, the process cartridge 2 is configured to be inserted into the apparatus main body 1 from the front side in FIG. 1 and then lowered to be set at a predetermined position. When the process cartridge 2 is lowered, the cam surface 5b of the swing arm 5 is By lowering the swing arm 5 while contacting a member (not shown) on the apparatus body side, the swing arm 5 moves to the second position.
From the state shown in the figure, it rotates counterclockwise around the swing shaft 5a against the torsion coil spring 7 in the figure, and is protected by a link mechanism composed of both swing arms 5 and 6 and the protective cover 4. 4 is moved to a predetermined position above the transfer guide 10b and positioned and fixed as shown in FIG. As a result, the protective cover 4 and the transfer guide 10b constitute a pair of upper and lower guides for guiding the sheet material from the registration rollers 9a and 9b to an optimum position between the photosensitive drum 3 and the transfer charger 11, and the photosensitive drum. It is possible to always transfer the above toner image excellently.

In the above embodiment, the swing center shafts 5a and 6a of both swing arms 5 and 6 are provided on the side wall surface of the process cartridge 2. However, one of the swing arms 5 rotates the photosensitive drum 3. You may make it rock | fluctuate about a shaft.

FIG. 3 is a vertical cross-sectional view of the essential parts showing another embodiment of the present invention.

In this example, the protective cover 4 is configured to be movable along the cam groove 16 directed to the side wall surface of the process cartridge 2 through the support member 15, and the protective cover 4 is provided on the main body side of the electromagnetic solenoid 17. The transfer guide 10 is moved from a position where the exposed portion of the photosensitive drum 3 is covered by the protective cover moving operation lever 18.
It is designed to be moved to a predetermined position on b.
The protective cover moving operation lever 18 is provided on the main body 1 of the shaft 18a.
Is provided so as to be swingable about a center, and an electromagnetic solenoid 17 is connected to an intermediate portion thereof with a plunger 17a by a pin 19 or the like. 2
Reference numeral 0 denotes a protrusion formed on the support member 15 that abuts on the free end of the lever 18, and reference numeral 21 denotes a return coil spring of the protective cover 4. Other configurations are the same as in the case of the above example.

When the process cartridge 2 is removed from the apparatus main body 1, the protective cover 4 is attached to the photosensitive drum 3 as shown by the chain line in FIG.
It is in a position to cover the exposed part of. When the cartridge 2 is set at a predetermined position in the apparatus main body 1, the solenoid 17 is energized, the plunger 17a is attracted, and the operation lever 18
Rotates clockwise about the shaft 18a from the position shown by the chain line in the figure against the return coil spring 21, and the protective cover 4 becomes a supporting member.
Along with the cam groove 16, it moves from the chain line position in the figure to the solid line position along with the cam groove 16, and is positioned and fixed at a predetermined position above the transfer guide 10b. Also, when the solenoid 17 is de-energized, the return coil spring 21 causes the protective cover 4 to return to the position shown by the chain line in the figure.

The mechanism for moving the protective cover 4 is not limited to the illustrated example, and various configurations are conceivable.

Further, in the illustrated example, the protective cover 4 is also used as the transfer guide, but the present invention is not limited to this, and if it is a kind of sheet material feeding guide, discharge guide, and other guides that regulate the movement of the sheet material, It can also be used as various other guide members.

C. Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

By using the protective cover that covers the exposed portion of the photoconductor when the process cartridge is removed as the sheet material conveyance guide when mounting the process cartridge, it is possible to reduce the parts cost and assembly cost by reducing the number of parts. .

Since the protective cover is always used as a functional component, there is no need for a space inside the device body for simply accommodating and disposing it inside the device body without using the protective cover at the time of mounting the cartridge as in the conventional case described above, and it is possible to reduce the size of the device. It will be possible.

It is possible to improve the arrangement position accuracy of the photoconductor that serves as a reference for image formation at the time of image formation and the sheet material conveying guide with respect to the photoconductor, thereby improving the image quality.

When the protective cover is retracted, the protective cover is retracted to the retracted position which is on the upstream side of the transfer region in the sheet material conveying direction and faces the guide member provided in the image forming apparatus. The cover cooperates with the guide member to reliably guide the sheet material toward the transfer area of the photoconductor.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a front view of a process cartridge, and FIG. 3 is a vertical sectional front view of a main part of an image forming apparatus of another embodiment. Fourth
FIG. 5 is a vertical sectional front view of a conventional image forming apparatus, and FIG. 5 is a front view of a process cartridge thereof. 1 is an apparatus main body, 2 is a process cartridge, 3 is an image carrier (photosensitive drum), and 4 is a protective cover.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP 62-201468 (JP, A) JP 59-195250 (JP, A) JP 57-123238 (JP, U)

Claims (2)

(57) [Claims] 1. A process cartridge detachably mountable to an image forming apparatus for forming an image on a sheet material, the process cartridge comprising: a guide member for guiding a sheet material conveying direction; A processing unit, a protective cover capable of having a protective position for protecting a transfer area of the photosensitive member for transferring a toner image formed on the photosensitive member to the sheet material, and a retracted position retracted from the protected position. According to the operation of mounting the process cartridge in the image forming apparatus, the protective cover is retracted to a retracted position which is on the upstream side of the transfer region in the sheet material conveyance direction and which faces the guide member. A protective cover driving unit, and the protective cover is installed in the image forming apparatus on the upstream side of the transfer area with respect to the sheet material conveyance direction. Was guide member is retracted into the opposite retracted position, the process cartridge being characterized in that a configuration that also serves as a conveyance guide of the sheet material. 2. An image forming apparatus for forming an image on a sheet material, wherein a process cartridge is attachable / detachable, a, a photoconductor, a process unit acting on the photoconductor, and a toner formed on the photoconductor. Protective cover for protecting the transfer area of the photoconductor for transferring an image to the sheet material, and a retractable position for retracting from the protective position, and an operation for mounting the process cartridge in the image forming apparatus According to, the protective cover drive means for retracting the protective cover to the retreat position on the upstream side of the transfer area with respect to the conveyance direction of the sheet material and facing the guide member, The protective cover is retracted to a retracted position on the upstream side of the transfer area with respect to the transport direction of the sheet material and facing a guide member provided in the image forming apparatus. And a mounting portion for detachably mounting the process cartridge configured also as a conveyance guide for the sheet material; b, a protective cover retracted to the retracted position of the process cartridge mounted in the mounting portion. And a guide member that is provided so as to face the conveyance direction of the sheet material, and an image forming apparatus.