JP3748784B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus in which a transfer material is pressed against an image carrier by a transfer member to transfer a toner image onto the transfer material.
[0002]
[Prior art]
In a copying machine or the like as an example of an image forming apparatus, a transfer roller (transfer member) is used to transfer a toner image formed on a peripheral surface of a photosensitive drum (an example of an image carrier) onto paper or the like (an example of a transfer material). The paper or the like is guided to a predetermined transfer position by a paper guide (an example of a guide member) brought close to an example), and the paper or the like is pressed against a part of the peripheral surface of the rotating photosensitive drum by the transfer roller. The toner image is transferred. At this time, in order to keep the image quality of the transferred image on the paper or the like above a certain level, it is necessary to accurately position the transfer roller, the paper guide, and the like with respect to the photosensitive drum.
On the other hand, when a paper jam occurs between the transfer roller and the photosensitive drum or the paper guide, or when the transfer roller peripheral surface is contaminated, the jammed paper is removed or the transfer roller peripheral surface is cleaned. Maintenance is required. Therefore, it is necessary to support the transfer roller and the paper guide adjacent to the transfer roller so that they can be separated, and it is desirable that the separation is easy. In view of such needs, Japanese Patent Application Laid-Open No. 11-93940 (Prior Art A) has a non-circular cross-sectional small diameter portion at the end of the rotation shaft of the transfer roller as a method for easily supporting the transfer roller. It has been proposed to provide a collar, a handle portion, and the like, and to make the transfer roller easy to attach and detach by rotating the small diameter portion in an attachable and detachable direction by operating the handle portion.
[0003]
[Problems to be solved by the invention]
However, in the prior art A, there is a problem that it is necessary to attach and detach the paper guide with a screw or the like when attaching and detaching the transfer roller during the maintenance, which requires a lot of trouble for the maintenance. Furthermore, there may be a problem in that the positional relationship between the transfer roller and the paper guide is shifted due to screw tightening.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately position the transfer member and the guide member that guides the transfer material to the transfer position with respect to the image carrier, and to maintain the transfer member. To provide an image forming apparatus that can easily separate a guide member adjacent to the transfer member.
[0005]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an image carrier supporting means for rotatably supporting an image carrier about a horizontal first rotation axis, and a toner image on the image carrier on a transfer material. The transfer member supporting means for rotatably supporting the transfer member to be transferred around a second rotation axis parallel to the first rotation axis, and the transfer material fed from the lower side close to the transfer member A guide member that leads to a transfer position by a transfer member, and the guide member is supported by the transfer member support means so as to be vertically rotatable within a predetermined rotation range,
The transfer member support means and the guide member are respectively positioned with respect to the image carrier support means by abutting against the image carrier support means, and the transfer member support means is positioned with respect to the image carrier support means. The guide member is configured to rotate to its lower position separated from the transfer member by its own weight when separated from the means in the horizontal direction.
As a result, the transfer member support means and the guide member are positioned with high accuracy with respect to the image carrier support means. As a result, the transfer member and the guide member are positioned with high accuracy with respect to the image carrier. The image quality is kept above a certain level.
Furthermore, when the transfer member path is maintained by separating the transfer member support means and the image carrier support means, the guide member is separated from the transfer member, so that the maintenance of the transfer position is facilitated.
And a spring for pressing the transfer material support means toward the image carrier support means at a position between the abutment portions of the transfer member support means and the guide member with respect to the image carrier support means. Thus, the pressing by the spring is not biased to one of the contact portions and is stabilized.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments and examples of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. The following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.
1 is a cross-sectional view of the main part of the image forming apparatus A according to the embodiment of the present invention with the cover portion opened, and FIG. 2 is a cover part of the image forming apparatus A according to the embodiment of the present invention. FIG. 3 is a perspective view of the transfer device of the image forming apparatus A according to the embodiment of the present invention, in which the paper guide is open, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a perspective view of the image forming apparatus A according to the present invention in which the paper guide is closed, FIG. 5 is a cross-sectional view of the image forming apparatus A according to the embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view of the image forming apparatus A according to the embodiment of the present invention with a cover portion closed.
[0007]
Image forming apparatus A is a copier that is an example of an image forming apparatus according to an embodiment of the present invention.
First, a schematic configuration of the image forming apparatus A will be described with reference to FIG. In FIG. 5, the left side is the front of the image forming apparatus A. The image forming apparatus A is mainly composed of a main body 1 and a cover 60. The cover 60 is provided with rails 61. The cover 60 is supported by the rail 61 supported by the main body 1 in a horizontal direction from the front of the image forming apparatus A to the main body 1 ( It is supported so that it can be detached and attached in the direction of separation). When the cover 60 is pressed against the main body 1, the latch lever 62 rotatably supported by the cover 60 is hooked on the latch pin 2 provided on the main body 1, as shown in FIG. The cover 60 is bonded and held to the main body 1 (cover closed state). Further, by removing the latch lever 62 from the latch pin 2 and pulling the cover part 60 away from the main body part 1, the cover part 60 can be separated from the main body part 1 (cover open state). .
Next, the configuration of the main part of the image forming apparatus A will be described with reference to FIG. The main body 1 includes a photosensitive drum 11 (an example of the image carrier) that forms a toner image on the peripheral surface thereof, a charging device 91 that applies an electrostatic charge to the photosensitive drum 11, and a toner on the peripheral surface of the photosensitive drum 11. A developing device 92 that forms an image, a cleaning device 93 that removes toner on the photosensitive drum 11 remaining after the transfer of the toner image onto paper or the like (an example of the transfer material), and a transfer of paper or the like from below to above A paper feed roller 94 that feeds to a position and a main body frame 10 (an example of the image carrier support means) that is a member that supports the photosensitive drum 11 and the like are installed.
Also, the cover portion 60 is a member for supporting a predetermined device involved in transferring the transfer device frame 20 (an example of the transfer member supporting means) is supported so as to be floating, the disjunction of the transfer device frame 20 A first spring 31 is provided to press from the direction toward the main body 1. Further, a transfer roller 21 (an example of the transfer member) that transfers the toner image onto paper or the like by being brought into pressure contact with the peripheral surface of the photosensitive drum 11 by the transfer device frame 20, paper fed from the paper feed roller 94, or the like. A paper guide 40 (an example of the guide member) that guides the toner to the transfer position, a second spring 32 that presses the rotating shaft 21a of the transfer roller 21 in a predetermined direction, and a charge removal that removes charge from the paper after the toner image is transferred. The apparatus 50 is supported and constitutes the image transfer apparatus 22.
[0008]
The photosensitive drum 11 is supported by the main body frame 10 so as to be rotatable about a rotation shaft 11a (first rotation shaft) that is horizontal and perpendicular to the separation / contact direction, and around the charging device 91 and the developing device. 92, a cleaning device 93 and the like are disposed, and the paper feed roller 94 is disposed below the photosensitive drum 11.
The transfer device frame 20 is provided with an insertion pin 20 c that protrudes toward the main body 1, and an insertion hole 10 c into which the insertion pin 20 c is inserted is provided in the main body frame 10. The insertion hole 10c is formed in a shape such that when the insertion pin 20c is inserted, the upper surface and the lower surface of the insertion pin 20c are in contact with the inner surface of the insertion hole 10c.
The transfer device frame 20 is provided with a hemispherical abutting portion 20a that abuts against the first abutting surface 10a that is a part of the main body 1 when the cover is closed. Similarly, an abutting portion 40b that abuts against the abutting surface 10b of the main body 1 is provided.
The transfer device frame 20 is supported by the cover portion 60 so as to be slidable in the separation / contact direction. The first spring 31 is provided between the contact portions 20a and 40b when viewed in the vertical direction, one end thereof is supported by the cover portion 60, and the other end is connected to the transfer device frame 20 with respect to the separation / contact. It is installed so as to be pressed from the direction toward the main body 1.
A foam material such as urethane rubber is applied to the peripheral surface of the transfer roller 21 so that paper or the like can be brought into close contact with the peripheral surface of the photosensitive drum 11.
The transfer roller 21 has a rotation shaft 21 a (second rotation shaft) parallel to the rotation shaft 11 a of the photosensitive drum 11, and the second rotation shaft 21 a is applied to the transfer device frame 20. The groove 20d having a width substantially equal to the diameter of the second rotating shaft 21a is supported so as to be rotatable and slidable obliquely upward. One end of the second spring 32 is supported by the groove 22d, and the other end is configured to push up the second rotating shaft obliquely upward. The sliding direction of the rotating shaft 21a is set to a direction toward the rotating shaft 11a of the photosensitive drum 11 when the cover is closed. The first and second springs 31 and 32 are selected so that the pressing force in the separating direction by the second spring 32 is smaller than the pressing force in the separating direction by the first spring 31. Has been.
The paper guide 40 is supported by the transfer device frame 20 so as to be vertically rotatable around a shaft 40a parallel to the rotation shaft 11a of the photosensitive drum 11 within a predetermined rotation range.
The static eliminator 50 supported close to the top of the transfer roller 21 is a discharge tip electrode or the like to which a high voltage is applied, and is supported by the transfer device frame 20.
As shown in FIG. 3, the transfer device frame 20, the paper guide 40, and the static eliminator 50 extend to both ends of the transfer roller 21 along the direction of the rotation shaft 21a of the transfer roller 21. Two contact portions 20c and 20a and 40b are provided at both ends of the transfer roller 21, respectively.
[0009]
When the paper guide 40 is pulled out of the cover portion 60 into the cover open state, the paper guide 40 is rotated to the lower end side of the rotation range by its own weight and is separated from the transfer roller 21. The transfer device frame 20 is rotatably supported so as to hold (paper guide open state). FIG. 3 is a perspective view of the transfer device 22 constituted by the transfer device frame 20 and the transfer roller 21 supported by the transfer device frame 20 in the open state of the paper guide.
When the cover 60 is opened as described above, the transfer roller 21, the photosensitive drum 11 and the paper guide 40 are separated from each other, and the peripheral surface of the transfer roller 21 is widely exposed. In addition, maintenance work such as cleaning of the peripheral surface of the transfer roller 21 is facilitated.
Further, when the cover part 60 is pushed and brought close to the main body part 1, the insertion pin 20 c is inserted into the insertion hole 10 c and a part of the paper guide 40 is brought into contact with the contact surface 10 b of the main body part 1. It contacts and rotates to the upper end side of the rotation range. When the cover 60 is further pressed until the cover is closed, a part of the peripheral surface of the transfer roller 21 is part of the peripheral surface of the photosensitive drum 11 by the pressing of the second spring 32 as shown in FIG. And the contact portion 20a contacts the first contact surface 10a. At the same time, the contact portion 40b contacts the second contact surface 10b to determine the inclination of the paper guide 40, and the paper guide 40 is pressed toward the upper end side of the rotation range to transfer the transfer roller 21 is held in proximity (paper guide closed state). FIG. 4 is a perspective view of the transfer device 22 in the paper guide closed state. In this state, the paper or the like fed from the paper feed roller 94 by the paper guide 40 can be accurately guided to a position where the transfer roller 21 and the photosensitive drum 11 are in pressure contact with each other.
As a result, the insertion pin 20c is restrained in the vertical direction, whereby the transfer device frame 20 is positioned in the vertical direction with respect to the main body frame 1. At the same time, the state in which the contact portions 20a and 40b are in contact with the contact surfaces 10a and 10b of the main body frame 1 by the pressing of the first spring 31 is maintained. Positioning in the separation / contact direction will be performed.
Here, since the pressing force of the second spring 32 is smaller than the pressing force of the first spring 31 in the separation / contact direction, the reaction force of the pressing of the second spring 32 is reduced. The transfer device frame 20 is not separated from the main body frame 10 by force. The photosensitive drum 11 is supported by the main body frame 1, and the transfer roller 21, the paper guide 21, and the charge eliminating device 50 are supported by the transfer device frame 20. Therefore, the distance between the paper guide 40 and the static eliminator 50 is fixed. Further, the pressing force of the transfer roller 21 against the photosensitive drum 11 is always constant by the pressing of the second spring 32. Furthermore, since the pressing position of the first spring 31 is configured to be between the contact portions 20a and 40b when viewed in the vertical direction, the pressing by the first spring 31 is performed on one contact portion. It is stable without being biased.
[0010]
As described above, the photosensitive drum 11, the transfer roller 21, and the paper guide 40 can be separated from each other only by pulling out the cover 60 from the main body 1 without any special operation such as screw tightening. Therefore, maintenance such as removal of jammed paper or cleaning of the transfer roller 21 is facilitated.
Further, the distance between the transfer roller 21 and the paper guide 40 and the static eliminator 50 with respect to the photosensitive drum 11 and the inclination of the paper guide 40 are always constant by an easy operation of simply pressing the cover 60 against the main body 1. Can be positioned. In addition, the pressure contact state of the transfer roller 21 with respect to the photosensitive drum 11 can be kept constant regardless of changes over time such as deterioration of the surface of the transfer roller 21. Therefore, the image quality of the transferred image on paper or the like is always kept above a certain level.
[0011]
The image forming apparatus A is an example of a copying machine, but the image forming apparatus to which the present invention can be applied includes a printer, a FAX, and the like.
[0012]
【The invention's effect】
As described above, according to the present invention, since the transfer member and the guide member that guides the transfer material to the transfer position can be accurately positioned with respect to the image carrier, the image quality of the transfer image onto the transfer material is always above a certain level. Can be kept in. Further, the guide member adjacent to the transfer roller can be easily separated, and maintenance such as cleaning of the transfer roller is facilitated. Further, the pressing by the first spring is stable without being biased to one contact portion of the transfer member support means and the guide member.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of an image forming apparatus A according to an embodiment of the present invention with a cover part opened.
FIG. 2 is a cross-sectional view of the main part of the image forming apparatus A according to the embodiment of the present invention with the cover part closed.
FIG. 3 is a perspective view of the transfer device of the image forming apparatus A according to the embodiment of the present invention with the paper guide open.
FIG. 4 is a perspective view of the transfer device of the image forming apparatus A according to the embodiment of the present invention, with the paper guide closed.
FIG. 5 is a cross-sectional view of the image forming apparatus A according to the embodiment of the present invention with the cover portion opened.
FIG. 6 is a cross-sectional view of the image forming apparatus A according to the embodiment of the present invention with the cover portion closed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main body part 2 ... Latching pin 10 ... Main body frame 10a ... 1st contact surface 10b ... 2nd contact surface 10c ... Insertion hole 11 ... Photosensitive drum 11a ... 1st rotating shaft 20 ... Transfer device frame 20a ... Abutting portion 20c ... Fitting pin 20d ... Groove portion 21 ... Transfer roller 21a ... Second rotating shaft 22 ... Transfer device 31 ... First spring 32 ... Second spring 40 ... Paper guide 40a ... Axis 40b ... Abutting portion 50 ... Static eliminating device 60 ... Cover 61 ... Rail 62 ... Latch lever 91 ... Charging device 92 ... Developing device 93 ... Cleaning device 94 ... Paper feed roller

Claims (2)

Image carrier support means for supporting the image carrier rotatably about a horizontal first rotation axis;
Transfer member support means for rotatably supporting a transfer member for transferring a toner image on the image carrier onto a transfer material around a second rotation axis parallel to the first rotation axis;
An image forming apparatus having a guide member that is close to the transfer member and guides the transfer material fed from below to a transfer position by the transfer member.
The guide member is supported by the transfer member support means so as to be rotatable up and down within a predetermined rotation range,
The transfer member support means and the guide member are respectively positioned with respect to the image carrier support means by abutting against the image carrier support means, and the transfer member support means is positioned with respect to the image carrier support means. An image forming apparatus comprising: the guide member configured to rotate by its own weight to a lower position separated from the transfer member when the guide member is separated from the means in the horizontal direction.   A spring that presses the transfer material support means toward the image carrier support means at a position between the abutting portions of the transfer member support means and the guide member with respect to the image carrier support means. Item 4. The image forming apparatus according to Item 1.

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