JPH0553449A - Transfer device - Google Patents

Abstract

PURPOSE:To provide a transfer device with a structure generating no defective transfer. CONSTITUTION:One 2A of a pair of transfer paper conveying guides 2 faced to each other across a transfer paper conveyance path is switched from the separating posture from a photosensitive body 5 to the approaching posture at the preset timing after the tip of the transfer paper is detected, thus the level that the front and rear ends of the transfer paper collide with the photosensitive body 5 or drop is reduced, and the adhesion is improved. The transfer paper is separated from the photosensitive body 5 when it is not passing, thus the sucking phenomenon of toner from the photosensitive body 5 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device, and more particularly to a transfer paper conveyance guide mechanism.

[0002]

As is well known, an image forming process in an image forming apparatus such as a copying machine includes a transfer process for electrostatically transferring a toner image carried on a photoconductor onto a transfer paper. It is provided. As the structure of the above-mentioned transfer device, a guide member for conveying and guiding the transfer paper toward the image leading edge position of the photoconductor after the paper feeding timing is set from the idea value, and the guide member for conveying and guiding. The corona discharger, which is located on the downstream side of the guide member in the conveying direction of the transfer paper and faces the photoconductor, constitutes the main part.

The above-mentioned guide member may be charged by frictional contact with the transfer paper, and the toner adhered on the photosensitive member by the action of the electric field due to this charging.
Was sometimes sucked by the guide member, which could cause stains on the back of the transfer paper.

Therefore, in order to prevent such a phenomenon,
For example, the guide member is made of a conductive member, and when the transfer sheet is not conveyed, it is grounded to prevent reverse transfer of the toner on the photosensitive member due to charging (for example, the actual development method). 64-51964).

[0005]

By the way, regarding the above-mentioned guide member, it is necessary to set the following functions. That is, (1) it is possible to transfer a clear image, in other words, to prevent a blurred image from being transferred, and (2) to be able to perform a transfer without causing image loss at the leading edge of the transfer paper. , (3) To prevent image dropouts at the trailing edge of the transfer paper, (4) To prevent stains on the transfer paper, and (5) To prevent transfer failures even with environmental changes such as humidity. There are times when you don't want to wake it up.

That is, the items (1) to (3) are all dependent on the distance between the guide member and the photosensitive member, and the items (4) and (5) are electric of the guide member. It depends on specific characteristics.

Therefore, in the structure of the conventional guide member described above, the functions relating to the above (4) and (5) can be satisfied, but the other functions cannot be satisfied. As a result, there is a problem that a transfer failure, that is, a transfer of a blurred image or an image dropout easily occurs.

Therefore, in view of the above-mentioned problems in the conventional transfer device, it is an object of the present invention to obtain a transfer device having a structure capable of preventing transfer defects.

[0009]

In order to achieve this object, the present invention is a transfer device for transferring a toner image carried on a photoconductor, which is conveyed toward the transfer position of the photoconductor. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper is the downstream side in the transfer paper transport direction. It is characterized in that the tip corresponding to the above is set to a first position that approaches the photoconductor and a second position that separates from the photoconductor.

Further, the present invention is a transfer device for transferring a toner image carried on a photoconductor, and the transfer device is vertically moved across a transfer path of a transfer paper which is conveyed toward a transfer position of the photoconductor. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper has a tip corresponding to the downstream side in the transport direction of the transfer paper close to the photoconductor. It is configured to be set to a first position and a second position that is separated from the first position, and this position setting is performed by the transfer paper passage detection unit provided in the lower guide member. The first position is set at a predetermined timing from the time when the passage is detected.

Further, the present invention is a transfer device for transferring a toner image carried on a photoconductor, which is moved up and down across a conveyance path of a transfer paper which is conveyed toward the transfer position of the photoconductor. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper has a tip corresponding to the downstream side in the transport direction of the transfer paper close to the photoconductor. It is configured to be set to a first position and a second position that is separated from the first position, and this position setting is performed by the transfer paper passage detection unit provided in the lower guide member. It is characterized in that the second posture is set when a case where no passage is detected is detected.

[0012]

According to the present invention, when the transfer paper is conveyed to the transfer position with respect to the photoconductor, the gap between the transfer paper and the photoconductor is adjusted.

Further, according to the present invention, when the front end of the transfer paper passes through the transfer area, the rear end of the transfer paper is brought closer to the photosensitive member side to improve the close contact state.

Further, according to the present invention, when the transfer paper does not pass through, the gap between the guide member and the photoconductor is expanded to prevent the toner on the photoconductor from transferring to the guide member.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic layout diagram showing a main structure of a transfer device according to an embodiment of the present invention. In FIG. 1, the transfer device 1 is guided to an upstream side in a transfer paper conveying direction indicated by an arrow A. A member 2 is provided, and a corona charger 3 for transfer and a charger 4 for separation are provided on the downstream side of the guide member 2, respectively. The above-mentioned guide member 2 is composed of a pair of plate members that vertically oppose each other across the transfer paper transport path, and at least the lower guide member 2A thereof is included.
A conductive material such as metal is used, and an insulating layer such as mylar is formed on the surface facing the transfer paper to make the charging effect effective at the time of transfer.

The lower guide member 2A is located on the downstream side of the transfer sheet in the conveying direction, that is, the transfer corona charger 3.
The tip on the side close to is divided from the other portion, and a fulcrum is set at the other portion to be swingably supported. Therefore, the lower guide member 2A has a second position corresponding to a first position in which its tip portion is in a position to approach the photoconductor 5 and a position in which it is spaced apart from the photoconductor 5, on the contrary. The posture and the posture are selected, and the posture is set by the posture setting member 6 described later. That is, the posture setting member 6 described above is the lower guide member 2
An eccentric cam 6A that comes into contact with the lower surface of the front end of A and a control unit 6C that uses an eccentric cam 6A for driving rotation of the eccentric cam 6A as an actuator unit are provided.
A signal from a photo sensor 7 which is a transfer paper passage detection member is input to the.

In the control section 6C, the front end of the lower guide section 2A is moved to the first position at a predetermined timing from the time when the photo sensor 7 detects the passage of the transfer paper, specifically, the passage of the front end. The rotation amount and the rotation direction of the rotation driving motor 6B are set so that the lower guide member 2A is oscillated by the eccentric cam 6A. The distance between the lower guide member 2A and the photoconductor 5 in the first position is 1.2 to 6 mm until a position of about 5 to 6 mm from the front end of the transfer paper passes.
It is about 1.6 mm.

In the control section 6C, when the passage of the transfer sheet by the photo sensor 7 is not detected, that is, in this case, the rear end of the transfer sheet is the photo sensor 7.
, The lower guide member 2A is set to the second position, the rotation amount and the rotation direction of the rotary drive motor 6B are set, and the lower guide member 2 by the eccentric cam 6A is set.
The swing displacement A is performed. The distance between the lower guide member 2A and the photoconductor 5 in the second position is 0.5 to 0.8 mm until the position on the rear end side of the transfer paper from 5 to 6 mm passes. It is designed to be of a degree.

The reason for setting the above-mentioned first and second postures is as follows. That is, the phenomenon that the transfer image is missing at the leading edge of the transfer paper is caused by the above-described lower guide member 2A.
If the distance between the sound of the transfer paper and the sound of the photoconductor is narrow, the tip of the transfer paper abuts against the photoconductor 5 by the conveying force and is bent in a direction away from the photoconductor 5, so that the adhesion between the transfer paper and the photoconductor is impaired. This is to prevent such inconvenience when the interval is narrow by enlarging the interval.

Further, the image dropout at the trailing edge of the transfer paper occurs because the peeling discharge occurs due to the vibration when the transfer paper falls downward when passing through the lower guide member. This is to reduce the degree of peeling by narrowing the interval so that the value does not become large.

Since this embodiment has the above-mentioned configuration,
Now, when the position of the lower guide member 2A is set and an experiment is performed on the phenomenon of missing transfer images at the leading edge and the trailing edge of the transfer paper, the results shown in FIG. 2 are obtained. That is, FIG.
Indicates the distance between the lower guide member 2A and the photoconductor 5 on the horizontal axis, and the vertical axis indicates the degree of occurrence of so-called white voids in the transferred image, and the number on the vertical axis. The size of indicates that it is unlikely that image dropout will occur. In FIG. 2, at the leading edge of the transfer sheet, a second position in which the interval between the lower guide member 2A and the photoconductor 5 is increased is set so that image dropout is reduced, and the trailing edge of the transfer sheet is reduced. In (2), the above-described second position is set to reduce the interval, and thus image dropout is reduced.

Further, by setting the second position to the lower guide member 2A at a predetermined timing from the leading edge of the transfer paper, that is, when the transfer paper is conveyed a predetermined distance, the transfer paper and the photoconductor 5 are separated from each other. By improving the adhesion, so-called phenomenon in which an image is transferred in a blurred state can be prevented.

On the other hand, in this embodiment, regarding the setting of the second position in the lower guide member 2A described above, in addition to preventing image loss at the trailing edge of the transfer paper, stains on the transfer paper, especially The second position is also set in order to prevent stains on the lower surface of the transfer paper facing the surface of the lower guide member 2A. That is, an insulating layer is formed on the lower guide member 2A described above on the surface facing the transfer paper, and even when transferring to a transfer paper containing a large amount of water, the charged electric charge is released through the discharge by the corona charger 3. It is designed to prevent transfer defects in high-humidity environments, but when the humidity is low, this insulating layer is frictionally charged by rubbing against the transfer paper during transport. And the electric field strength between the sounds of the photoconductor 5 is different due to this charged electric charge, so that the toner attached to the photoconductor 5 is electrostatically attracted to the lower guide member 2A side. Occurs. Therefore, since the toner suction phenomenon on the photoconductor 5 is affected by the distance between the lower guide member 2A and the photoconductor 5,
When the transfer sheet is not passed, that is, when the image formation of the photoconductor 5 is not performed, it is necessary to separate the lower guide member 2A from the photoconductor 5. And, this interval requires about 1 mm or more.

In view of this, in the present embodiment, when the control section 6C described above receives a signal indicating that the photoconductor 5 is not forming an image, the transfer paper detection signal from the photosensor 7 is sent. Only when the output is not output, the eccentric cam 6A is drive-controlled so that the lower guide member 2A is separated from the photoconductor 5 at the above-described interval.

A specific example thereof will be described below with reference to FIGS. 3 and 4. FIG. 3 actually shows the distances between the respective parts in the transfer device shown in FIG. 1, and in the figure, the distance from the photosensor 7 to the transfer area, that is, the position of the corona charger 6B is set to 60 mm, and It is assumed that the distance between the corona charger 6B and the tip of the lower guide member is 8 mm. The latter distance is actually about 4 mm as a normal dimension and 8 mm as a maximum dimension. Then, after setting such a distance, the A4 size transfer paper is fed in the vertical direction, that is, the lower guide member 2A is set assuming that the transfer paper transport position in which the direction perpendicular to the transport direction is the longitudinal direction is set.
The timing chart relating to the posture setting is described as shown in FIG.

In other words, when the count of "0" in the pulse counter that takes in the clock pulse is used as the leading edge detection timing of the transfer sheet, "240" pulses are reached until the leading edge of the transfer sheet reaches the transfer area facing the corona charger 6B. Requires. After the leading edge of the transfer paper is detected, the eccentric cam 6A is rotationally driven at a timing (“224” pulse) corresponding to the time when the leading edge advances from the leading edge of the lower guide member 2A by, for example, about 6 mm. The lower guide member 2A is set to the first position, and the gap between the lower guide member 2A and the photoconductor 5 is narrowed to enhance the close contact state between the transfer paper and the photoconductor. Therefore, the transfer paper is kept in a state in which the interval between the transfer paper and the photoconductor is widened until the tip reaches the corona charger 6B, and is bent at the time of hitting the photoconductor. The occurrence of the phenomenon can be suppressed, and further, when the predetermined distance described above is reached, the distance between the photosensitive member 5 and the photosensitive member 5 is changed from the widened state to the narrowed state, and the vibration when the rear end falls downward is suppressed. It will be suppressed. It should be noted that while the remaining 2 mm of the distance traveled by the transfer paper loading end from the lower guide member tip is advanced, the corona charger
It is designed to keep Ja 6B in a dynamic position.

On the other hand, the trailing edge of the transfer sheet is detected at the "1188" pulse in opposition to the photosensor 7, and the control section 6C sets the distance (60 mm) from the detection time to the trailing edge of the trailing edge. The eccentric cam 6A is drive-controlled to separate the lower guide member 2A from the photoconductor 5 in order to set the second position of the lower guide member 2A at the "1428" pulse by adding the corresponding pulses.

The eccentric cam 6A in the above-mentioned posture setting member 6 may be replaced by a solenoid which enables swing displacement of the lower guide member 2A.

[0030]

As described above, according to the present invention, it is possible to set the guide member for guiding the conveyance of the conveyed transfer paper, that is, the position to approach the photosensitive member and the position to separate it from the photosensitive member. As a result, the contact state between the transfer paper and the photoconductor can be made uniform. Further, according to the present invention, by setting the position of the guide member, it is possible to prevent the image dropout by suppressing the phenomenon of abutting or dropping on the photoconductor at the leading edge or the trailing edge of the transfer paper. Therefore, it is possible to transfer an image without transfer failure.

Further, according to the present invention, since the guide member is separated from the photosensitive member when the image is not formed on the photosensitive member, the toner on the photosensitive member is attracted by the electric charge charged in the guide member. It is possible to prevent the back stain by preventing the toner from adhering to the back surface of the transfer paper.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram for explaining a configuration of a main part of a transfer device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the configuration shown in FIG.

FIG. 3 is a schematic layout diagram corresponding to FIG. 1 showing a specific dimensional relationship for explaining the operation using the main part configuration shown in FIG.

FIG. 4 is a timing chart for explaining control timing for the configuration shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer device 2 Guide member 2A Lower guide member 3 Transfer corona charger 5 Photoconductor 6 Position setting member 6A Eccentric cam 6B Drive motor 6C Control unit 7 Photo sensor which is a transfer paper detection member

Claims (3)

[Claims] 1. A transfer device for transferring a toner image carried on a photosensitive member, the pair being vertically opposed to each other with a transfer paper transfer path being transferred toward the transfer position of the photosensitive member interposed therebetween. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper is the first guide plate that approaches the photoconductor at the tip corresponding to the downstream side in the transfer paper conveyance direction. A transfer device, which is configured to be set to a position and a second position separated from the position. 2. A transfer device for transferring a toner image carried on a photoconductor, the pair being vertically opposed to each other with a transfer paper conveyance path being conveyed toward a transfer position of the photoconductor. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper is the first guide plate that approaches the photoconductor at the tip corresponding to the downstream side in the transfer paper conveyance direction. It is configured to be set to a posture and a second posture which is separated from the posture, and this posture setting detects the passage of the transfer paper in the transfer paper passage detecting portion provided in the lower guide member. The transfer device configured to set the first position with a predetermined timing from the time when the transfer is performed. 3. A transfer device for transferring a toner image carried on a photosensitive member, the pair being vertically opposed to each other with a transfer path of transfer paper being transferred toward the transfer position of the photosensitive member interposed therebetween. Of the pair of guide plates, the lower guide plate facing the lower surface of the transfer paper is the first guide plate that approaches the photoconductor at the tip corresponding to the downstream side in the transfer paper conveyance direction. It is configured to be set to a position and a second position separated from each other, and in this position setting, the transfer paper passage detection unit provided in the lower guide member does not pass the transfer paper. A transfer device configured to set the second position when a case is detected.