JP2001092265A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a separation pawl from being deformed or a photoreceptor from being damaged, because the opening angle of the separation pawl is small when recording paper is jammed. SOLUTION: The opening angle of the separation pawl is set to 75 deg. or higher and 90 deg. or smaller to a horizontal line.

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 such as a copying machine and a printer.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image on a recording sheet by charging, exposing, and transferring, a recording member on which a toner image has been transferred is discharged downstream of a separating means in a photosensitive member rotating direction of a separating means for separating the toner image from the photosensitive member. In many cases, a separation assisting means having a separation claw is provided. Such separation assisting means is provided for the purpose of preventing the recording sheet from jamming at the separation position in view of the fact that various types and properties of recording paper are used.

However, even with the provision of the separation assisting means, it is extremely difficult to completely eliminate the jam of the recording sheet at the separation position. In view of such a situation, in many image forming apparatuses, it is considered that the recording paper is not separated from the photoconductor and adheres to the photoconductor. The premise is to install a jam release mechanism.

[0004] In many cases, a separation claw as a separation assisting means is also configured to be suitable for a jam clearing operation. When the jam is cleared, the separation claw is opened to facilitate removal of the recording paper.

[0005]

A conventional separation claw is shown in FIG.
As shown in (2), the opening angle in the case of rotating at the time of clearing the jam and leaving a space between the photosensitive member and the photosensitive member is set to 25 °, and the upper limit thereof is set. However, the upper limit of 25 ° is not sufficient for removing jammed paper, and the jammed paper may apply a strong force to the separation claw, deform the separation claw, and possibly damage the photosensitive member. In addition, there is a problem that the recording paper that has been jammed contacts the photoconductor, or the recording paper contacts the photoconductor when the jammed paper is removed, thereby damaging the photoconductor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable image forming apparatus which solves the above-mentioned problem at the time of jam in a recording paper separating apparatus.

[0007]

The object of the present invention is as follows.
This is achieved by any of the following inventions.

(1) In an image forming apparatus for forming an image by forming a toner image on a photoreceptor by charging, exposing and developing, and then transferring the toner image to the recording paper, the recording paper passing through the transfer position is A separation unit for separating from the photoconductor is provided between the transfer unit and the cleaning unit,
Downstream of the separation means, separation assist means having a separation claw pivotally supported at a fulcrum, a spring for urging the separation claw toward the photoconductor, and a stopper for defining an opening angle of the separation claw are provided, The opening angle with respect to a line connecting the fulcrum of the separation claw and a contact point of the separation claw with the photoconductor is 35 to 60 °.
An image forming apparatus, wherein the stopper is set so as to fall within the range.

(2) The image forming apparatus according to the above (1), wherein the photoconductor is formed in a rotatable drum shape.

(3) The image forming apparatus according to (1) or (2), wherein the fulcrum of the separation claw is set at an angle of 25 to 40 ° with respect to a horizontal line.

(4) The opening angle with respect to the horizontal line is 60
The image forming apparatus according to the above (3), wherein the angle is set within a range of from 90 ° to 90 °.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a main part of the image forming apparatus.

The image forming apparatus charges the photosensitive member 10,
An image forming unit 23 that forms a toner image by performing exposure and development, transfers the toner image onto a recording sheet P by transfer, and fixes the image to form an image. The image forming unit 23 is a main body of the image forming apparatus. Are supported by the supporting frames A and B. The photoconductor 10 is a drum-shaped photoconductor in which an organic photoconductive layer is formed on a metal substrate such as a drum-shaped aluminum.
A belt-shaped thing can also be used. The photoreceptor 10 rotates clockwise as shown by the arrow during image formation.

Around the photoreceptor 10, a charger 11 for applying a uniform electric potential to the photoreceptor 10, an exposure device 12 for projecting an image of a document, and a toner for developing an electrostatic latent image on the photoreceptor 10 Developing device 13 for forming image, recording paper P by corona discharge
Transfer device 14 as a transfer unit for applying a transfer potential to the recording paper P, a separator 15 as a separation unit for removing the charge of the recording paper P by corona discharge, a separation claw 18 for assisting the separation operation of the separator 15 and the photoconductor 10. A cleaning device 22 is disposed as cleaning means for removing the toner remaining in the image forming apparatus.

A transport path for transporting the recording paper P is formed below the photoreceptor 10 along the transfer unit 14 and the separator 15.
The fixing device 20 is arranged on the conveyance path after the transfer.

An electrostatic latent image is formed on the photoconductor 10 by charging by the charger 11 and image exposure by the exposure device 12 in accordance with the rotation of the photoconductor 10 as indicated by the arrow. By the subsequent rotation of the photoconductor 10, a toner image is formed by the development of the developing device 13, and the formed toner image is transferred to the recording paper P.
The transferred toner image is fixed by the fixing device 20, and an image is formed on the recording paper P. The photoconductor 10 after the transfer of the toner image passes through the cleaning device 22 and is cleaned.

The recording paper P that has passed through the transfer unit 14 is
5 is separated from the photoreceptor 10 by the static elimination action of the cleaning device 2. In order to assist the separation action of the separator 15 and to ensure the separation, the cleaning device 2 is provided downstream of the separator 15.
The separation assisting means is arranged downstream of the second. The separation assisting means includes a plurality of separation claws 18A, 18B, 18C arranged in parallel in the rotation axis direction of the photoreceptor 10, a spring S1 for bringing these separation claws into light contact with the photoreceptor, and limiting the opening angle of these separation claws. It has a stopper 171 to perform. Separation claw 18A, 1
8B and 18C are made of hard resin or rubber. FIG. 2 is a diagram showing portions of the separation claws 18A, 18B, and 18C.
This is viewed from below in FIG. Also, FIG.
It is the front view which expanded and showed the part of 8A, 18B, 18C. 1 and 3 and FIGS. 4 and 5 described later.
, The separation claws 18A, 18B, 18C are collectively referred to as 18, and the release members 19A, 19B, 19C are collectively referred to as 1.
9, respectively. In the following description, 18
A, 18B, 18C are assumed to be 18 and 19A, 19
B and 19C will be described as 19, but the following description is applied to these three separating claws and the releasing member.

The separation claw support frame 17 shown in FIG.
1 (see FIG. 3) is formed at an acute angle, and a separation claw 18 having a small width is rotatably supported on a shaft. The tip 181 of the separation claw 18 is brought into contact with the surface of the photoconductor 10. A release member 19 is provided on each shaft 24 as an operating member for releasing. The separation claw 18 is urged in the X direction by a coiled spring S1 so that the distal end portion 181 contacts the photoconductor 10, as shown in an exploded state before its attachment in FIG. Further, an electromagnetic solenoid 25 for operating the release member 19 is provided at one end of the shaft 24 in the image forming apparatus main body. The electromagnetic solenoid 25 is actuated when the rotation of the photoconductor 10 is started to release the contact of the tip 181 of the separation claw 18 with the surface of the photoconductor 10 as shown by a dashed line in FIG. Simultaneously with the transfer of the toner image, the electromagnetic solenoid 25 is turned off, and is urged by the elastic force of the spring S1 to bring the tip 181 of the separation claw 18 into contact with the photosensitive member 10.

Further, an operation cam 26 is provided at one end of the separation claw support frame 17 which supports the separation claw 18, and a return spring S2 is provided at the other end.
Is arranged, and the operation cam 26 is operated to operate the separation claw support frame 17.
Is reciprocated right and left in the direction of the rotation axis of the photoconductor 10. The operation of such a device prevents the tip 181 of the separation claw 18 from dispersing the contact position with the surface of the photoconductor 10 over a wide area, thereby preventing the surface of the photoconductor 10 from being damaged.

As shown in FIG. 3, the separation claw support frame 17 is
Cleaning device 22 provided in image forming unit 23
, And provided so as to be movable in the direction of the arrow (shown in FIG. 2) in the direction of the rotation axis of the photoconductor 10 by the plurality of support members 27.

In the image forming step, the solenoid 25 is turned on at the same time as the rotation of the photosensitive member 10 at the start of image formation, and the separating claw 18 is rotated against the spring S1 as shown by the arrow Y to rotate the photosensitive member. 10 away from the surface. At the timing when the recording paper P reaches the separator 15, the solenoid 25 is turned off, and the tip 181 of the separation claw 18 is moved to the photosensitive member 1.
Lightly contact the surface of the recording paper P to assist the separation of the recording paper P.
Then, when the leading end of the recording paper P passes through the separator 15, the solenoid 25 is turned on, and the leading end 181 separates from the photoconductor 10 again.

The cam 26 rotates at a very low rotation speed such that one cycle of image formation of 100 sheets moves the separation claw 18 in the direction shown by the arrow in FIG. Change the contact position.

Next, a case where the recording paper P is jammed at the separation claw 18 due to a poor separation will be described with reference to FIGS. 4 and 5 show a portion of the separation claw 18 at the time of jam. A step 182 is formed at the rear of the separation claw 18 pivotally supported by the separation claw support frame 17 at the fulcrum 183, and a stopper 171 corresponding to the step 182 is formed on the separation claw support frame 17.

When a jam of the recording paper P occurs at the position of the separation claw 18, as shown in FIG.
4, the rotation angle is limited by the step 182 and the stopper 171. Also, when removing the jammed recording paper P, the separation claw 18 is rotated to an angle limited by the step 182 and the stopper 171 by the pulling force of the recording paper P, as shown in FIG.

As described above, the rotation angle of the separation claw 18 is limited by detecting the density of another component disposed near the installation position of the separation claw 18, for example, the toner image on the photosensitive member 10. This is for preventing the separation claw 18 from contacting the circuit board or the like of the density sensor. Further, the above-described limitation of the rotation angle is also intended to always reliably return the separation claw 18 to the correct operating position after the jam is released.

In the conventional image forming apparatus, the separation claw 1
As shown in FIG. 5, when the separation claw 18 is in contact with the photoreceptor 10, the opening angle from the line K connecting the fulcrum 183 and the tip 181 of the separation claw 18 is 25 °. And it was set narrow. For this reason, when a large force is applied to the leading end portion 181 of the separation claw 18 at the time of a jam, or when the jammed recording paper P is removed, the leading end portion 181 may be removed.
, A large force may be applied to deform the separation claw 18.

In the present embodiment, in order to eliminate such deformation of the separation claw 18, the opening angle of the separation claw 18 defined by the step 182 and the stopper 171, that is,
Separating claw 18 for the line connecting the fulcrum 183 and the tip 181
Is an angle in the range of 35 to 60 °, for example, 4
The stopper 171 was set with respect to the step 182 so as to be 5 °. FIG. 4 shows a state where the separation claw 18 in the present embodiment has been rotated to a limit angle (opening angle). As shown in the drawing, a large space is formed between the photoconductor 10 and the separation claw 18, so that a force that deforms the separation claw 18 due to the jammed recording paper P is prevented. . When removing the jammed recording paper P,
Similarly, the force applied to the separation claw 18 is reduced.

The rotation angle of the separation claw 18 is limited to 35.
If it is set smaller than °, the same problem as the conventional one as shown in FIG. 5 may occur. If the limit is set to be larger than 60 °, the rotation angle of the separation claw 18 is too large,
There is a possibility that the problem of difficulty in designing the first spring load may occur.

As shown in FIG. 1, a drum-shaped photoreceptor 10
In the configuration of the image forming apparatus in which the transfer of the toner image is performed at a position below the photoreceptor 10, the separating claw 18 is disposed between the separator 15 and the cleaning device 22, and the installation angle θ2 is The fulcrum 183 of the separation claw 18 is a horizontal line L
Is preferably set in the range of 25 to 40 °. In such a configuration of the image forming apparatus, it is desirable to configure the stopper 171 such that the opening angle θ3 of the separation claw 18 with respect to the horizontal line is an angle within the range of 65 to 90 °.

[0031]

According to the first aspect of the present invention, the separation claw is prevented from being deformed and the photosensitive member is prevented from being damaged by the recording paper jam at the separation position, and a highly reliable image forming apparatus is realized. . The removal of the jammed recording paper in the separation section was facilitated.

According to the second aspect of the present invention, when a drum-shaped photosensitive member, which is most widely used as an image forming apparatus, is used, the separation claw is deformed by the recording paper, particularly when a jam occurs, and the photosensitive member is exposed to light. Problems such as physical injury have been resolved.

According to the third aspect of the present invention, in the image forming apparatus configured to transfer the toner image to the recording paper below the photoreceptor, the separation claw is deformed or the photoreceptor is damaged by the jammed recording paper. Such a problem was solved particularly effectively.

According to the fourth aspect of the present invention, in the image forming apparatus configured to transfer the toner image to the recording paper below the photoreceptor, the separation claw is deformed or the photoreceptor is damaged by the jammed recording paper. Is reliably prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a part of a separation claw.

FIG. 3 is an enlarged view showing a part of a separation claw.

FIG. 4 is an enlarged view showing a part of a separation claw.

FIG. 5 is an enlarged view showing a portion of a separation claw in a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoreceptor 11 Charger 12 Exposure device 13 Developing device 14 Transfer device 15 Separator 16 Paper feeder 17 Separation claw support frame 18A, 18B, 18C Separation claw 19A, 19B, 19C Release member 22 Cleaning device 23 Image forming unit 24 Axis 171 Stopper 181 Tip 182 Step A, B Support frame S1, S2 Spring

Claims (4)

[Claims] An image forming apparatus for forming a toner image on a photoreceptor by charging, exposing, and developing, and then transferring the toner image to the recording paper to form an image. A separation unit for separating from the photoconductor is provided between the transfer unit and the cleaning unit, and a separation claw pivotally supported at a fulcrum downstream of the separation unit and a spring for urging the separation claw toward the photoconductor. A separation assisting unit having a stopper that defines an opening angle of the separation claw is provided,
The image forming apparatus according to claim 1, wherein the stopper is set such that the opening angle with respect to a line connecting the fulcrum of the separation claw and a contact point of the separation claw with the photoconductor is within a range of 35 to 60 degrees. 2. The image forming apparatus according to claim 1, wherein the photoconductor is formed in a rotatable drum shape. 3. The fulcrum of the separation claw is 2
3. The image forming apparatus according to claim 1, wherein the angle is set in a range of 5 to 40 [deg.]. 4. The angle of opening with respect to a horizontal line is 60-9.
The image forming apparatus according to claim 3, wherein the angle is set within a range of 0 °.