JPH0580599A - Photosensitive body unit for image forming device, belt-like photosensitive body constituting it, and driving means for the body - Google Patents

Abstract

PURPOSE:To prevent the slipping of a photosensitive belt and a driving means when the rotational direction of the photosensitive belt is changed over by constituting a belt-like photosensitive body to reversely rotate, and executing processing for increasing time coefficient of the friction of the contact region of the belt-like photosensitive body and the driving means. CONSTITUTION:The processing for increasing the coefficient of the friction of the contact region of the belt-like photosensitive body 203 and the driving means 20 is carried cut. In other words, the belt-like photosensitive body 203 constituted of a first layer composed of an elastic member and a second layer composed of a photoconductor on which image information is written, is suitable. A photosensitive body driving means rotating a photosensitive body in both forward and backward directions, can be obtained, as well, in such a manner that plural protrusions are formed on the surface of the driving means coming into contact with the belt-like photosensitive body 203. Thus, behavioral unstabilization in the switching of the rotational direction of the photosensitive body, is suppressed, to stably change a rotational direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive member unit used in an image forming apparatus such as a copying machine, a facsimile, a laser printer, etc., which uses an electrostatic recording process, a belt-shaped photosensitive member constituting the photosensitive member unit, and a driving means thereof. Specifically, a double-sided copying apparatus for recording image information on both sides of one recording sheet, or a photoconductor unit used for a composite copying apparatus for recording a plurality of image information on one side of one recording sheet. The present invention relates to a belt-shaped photosensitive member and a driving means for the photosensitive member.

[0002]

2. Description of the Related Art Regarding an apparatus for performing double-sided copying on a recording sheet, a sheet on one side of which is recorded from a fixing unit as disclosed in, for example, U.S. Pat. No. 4,098,551 and Japanese Patent Laid-Open No. 60-8863. A mechanism in which the sheet is once stacked on the intermediate tray via the reversing mechanism and then fed again to the transfer section via the sheet feeding resist section is known. However, such a double-sided copying mechanism inevitably requires an extremely long transport path length, and therefore the number of copies per unit time must be reduced as compared with single-sided copying.

That is, in such a double-sided copying mechanism, "low copying productivity" is mentioned as one of the major problems.

In recent years, particularly the social problem of environment and resource saving has been highlighted, and even from such a viewpoint, double-sided copying itself leads to effective use of resources, and copying that should be further popularized. Since it is considered to be a form, it can be said that solving the above-mentioned “low copy productivity” is also a social demand.

[0005]

For that purpose, for example,
Japanese Examined Patent Publication No. 63-46416, especially in FIG. 1, a double-sided copying machine with high productivity of double-sided copying, particularly, the most frequently used one among two-sided copying usage modes, 1
A high-productivity double-sided copying apparatus for double-sided copying to one, that is, double-sided copying with one set number of sheets has been proposed.

However, in such a double-sided copying machine, the belt-shaped photoconductor is capable of both forward and reverse rotations, and when the rotation direction is switched from forward rotation to reverse rotation and from reverse rotation to forward rotation. The behavior of the belt tends to be unstable.

Therefore, the present invention is applied to an image forming apparatus developed for improving the productivity of double-sided copying, and at the same time, for saving the space of a plurality of process units and efficiently arranging them in the apparatus space. In the photoconductor unit
A photosensitive member unit that suppresses the behavior destabilization of the belt-shaped photosensitive member that can be rotated in the forward and reverse directions when the rotational direction is switched from the normal rotation to the reverse rotation and from the reverse rotation to the normal rotation, and stably switches the rotation direction. An object of the present invention is to provide a belt-shaped photoconductor and a driving unit for driving the belt-shaped photoconductor.

[0008]

The present invention solves this problem by
In a photoconductor unit for an image forming apparatus having a belt-shaped photoconductor that can be rotated in the normal and reverse directions and a drive unit that stretches and drives the belt-shaped photoconductor, the friction coefficient in the contact region between the belt-shaped photoconductor and the drive unit is increased It is solved by applying processing.

A belt-shaped photosensitive member including a first layer made of an elastic member and a second layer made of a photoconductor on which image information is written is suitable for solving the above problems.

Further, a photosensitive member driving means having a plurality of projections formed on the surface contacting the belt-shaped photosensitive member and rotating the photosensitive member in both forward and reverse directions is also suitable for solving the above problems.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments based on the drawings.

FIG. 1 shows an image forming apparatus capable of double-sided copying and composite copying to which a photoconductor unit according to the present invention is attached, and FIG. 2 is an enlarged view of an image forming section thereof. In the image forming apparatus, the photoconductor belt 203 is wound around two rollers 201 and 202 having different diameters, and the photoconductor belt drive roller 201 having a large diameter is driven by the drive unit as indicated by arrows c and d. Both forward and reverse rotation is possible. Along with the rotation, the photoconductor belt 203 and the photoconductor belt driven roller 202 having a small diameter rotate.

A developing device 208 is installed facing the top of the photoconductor belt 203. Corresponding to the photoconductor belt 203 that can rotate both forward and backward, the developing roller 20 of the developing device 208
9, as well as the stirring paddles 211A and 211B, the stirring roller 210, the agitator 214 of the toner hopper portion, and the toner replenishing roller 213, which are both rotatable forward and backward.

The transfer charger 313 movable up and down is
It is provided inside the transfer belt 312 at a position facing the lowermost part of the photoconductor belt 203. When the recording sheet conveyed by the transfer belt 312 reaches the transfer position, the transfer charger 313 and this casing are provided. The transfer guide 328 moves upward to bring the photosensitive belt 203 and the recording sheet into close contact with each other, and transfer is performed in this state. The transfer direction of the transfer belt 312 is switched as needed, and the transfer process is performed at this position during both forward and reverse rotations.

As the other unit required for the electrophotographic process for executing the image forming process, the photosensitive belt 20 is used.
Two charging chargers 204A and 204B, two exposure positions, two cleaning units 206A and 206B, two erasers 205A and 205B, and two static elimination lamps 207A and 207B are installed around the circumference of 3. Each of these two units installed,
In order to obtain the same process conditions when the photoconductor belt 203 rotates in the normal and reverse directions, the photoconductor belt 203 is arranged in a bilaterally symmetrical positional relationship with respect to a line connecting the transfer portion and the developing portion.

A series of image forming processes are well known,
The operation sequence of each unit around the photoconductor will be described below.

In order to perform double-sided copying on a recording sheet,
First, when the photoconductor belt 203 rotates in the positive direction to copy on the front side of the sheet, that is, when the drive roller 201 follows the rotation in the direction of arrow c, the surface of the photoconductor belt 203 is uniformly minus by the charger 204A. The electric charge is applied, and the eraser 205A removes the charging potential of the non-image portion. Next, the photosensitive belt 203 is slit-exposed at the first exposure position by the exposure A guided from the optical system including the lens 106 occupying the upper portion of FIG. 1, and an electrostatic latent image is formed on the surface thereof.

Toner is adhered to the electrostatic latent image by the developing device 208 to form a visible image. Further static elimination lamp 20
The charge is removed before transfer by 7B, and the surface potential of the photoconductor belt 203 is lowered to prepare for the transfer step.

When the visible image on the photoconductor belt 203 reaches the transfer position, it is electrostatically adsorbed to the transfer belt 312 and the belt 31
The recording sheet synchronized by the first registration sensor attached to 2 is conveyed from the right side in the figure to the transfer position. Then, the transfer charger 313 and the transfer guide 328 provided in the casing are moved upward, and the photosensitive belt 203 and the recording sheet are brought into close contact with each other to perform the transfer.

After that, the transfer residual toner remaining on the photoconductor belt 203 is cleaned while passing through the cleaning unit 206A, and finally, the charge removal lamp 207A removes the residual charge on the surface of the photoconductor belt 203, and the next copy is performed. Prepared for a cycle.

The eraser 205B and the charger charger 204B are in operation during a series of copying cycles when the photosensitive belt is rotating forward.
Does not work. The cleaning unit 206B is retracted to a position where it does not contact the photoconductor belt 203.

When the photosensitive belt 203 rotates in the reverse direction to copy the front side to the back side of the transferred recording sheet, that is,
When the drive roller 201 follows the rotation in the direction of arrow d, the pair of units installed around the photoconductor belt has A and B opposite to the case of normal rotation, but the basic operation sequence is As in the case of positive rotation, the surface of the photoconductor belt 203 is uniformly given a negative charge by the charging charger 204B, and the eraser 205B removes the charging potential of the non-image portion. Then, the photoreceptor belt 203 is attached to the lens 10
Slit exposure is performed at the second exposure position by exposure B guided from an optical system including 6, and an electrostatic latent image is formed on the surface.

Toner is adhered to the electrostatic latent image by the developing device 208 to form a visible image. Further static elimination lamp 20
The charge is removed before transfer by 7A, and the surface potential of the photosensitive belt 203 is lowered to prepare for the transfer step.

When the visible image on the photosensitive belt 203 reaches the transfer position, it is accommodated in the reversing unit through the fixing unit 315 partially shown in the lower left part of the drawing of FIG. The recording sheet synchronized by the second registration sensor 325 is conveyed from the left side in the figure to the transfer position. And
The transfer charger 313 and the transfer guide 328 provided in this casing move upward, and the photoconductor belt 203 and the recording sheet are brought into close contact with each other to perform transfer. After the transfer, the recording sheet conveyed to the right side in the drawing from the transfer position is conveyed again to the fixing unit 315 through the transfer position by switching the transfer direction of the transfer belt 312. When passing through the transfer position again, the transfer charger 313 and the transfer guide 32
8 is in a lowered position.

The transfer residual toner remaining on the photoconductor belt 203 is cleaned while passing through the cleaning unit 206B, and finally, the charge removal lamp 207B removes the residual charge on the surface of the photoconductor belt 203, and the next copy is performed. Prepared for a cycle.

The eraser 205A and the charger charger 204A are operated during a series of copying cycles when the above-mentioned photosensitive belt is rotated in the reverse direction.
Does not work. The cleaning unit 206A is retracted to a position where it does not come into contact with the photosensitive belt 203.

It is also possible to rotate the photoconductor belt 203 in the forward direction to copy the front side of the transferred recording sheet to the back side. In that case, the recording sheet is passed through the fixing section 315 and accommodated in the reversing section. Electrostatically adhere to the transfer belt 312,
After the transfer charger 313 and the transfer guide 328 are lowered, they are once conveyed to the right side from the transfer position in the figure, and then synchronized with the first registration sensor attached to the belt 3112 to rotate the photoconductor belt forwardly. Back side copying is performed according to the operation sequence of time.

In the case of a composite copy in which a plurality of image information is recorded on one side of one recording sheet, the recording sheet which is electrostatically attracted to the transfer belt 312 and is once conveyed to the reversing unit without being transferred is the second recording sheet. Synchronized by the registration sensor 325, electrostatically adsorbed on the transfer belt 312 that rotates clockwise in the figure, and transferred and transferred according to the operation sequence during the reverse rotation. After the completion of the first transfer, the first registration sensor synchronizes with each other, and the reverse transfer conveys the composite transfer according to the operation sequence during the forward rotation.

In the photoconductor unit used in this image forming apparatus, for example, the front side of the photoconductor belt 203 is formed of an OPC (organic photoconductor) layer on which image information is to be written, and the back side is formed of an elastic member layer. Has been done. On the other hand, the surface of the drive roller 201 is sandblasted, and the contact area between the photoconductor belt 203 and the drive roller 201 is increased by this treatment and the material on the back side of the photoconductor belt. Slip prevention is achieved when the body is rotated in the normal direction to the reverse direction and when the body is rotated from the reverse direction to the normal direction.

Instead of sandblasting the surface of the driving roller, a highly viscous material is attached to the surface,
The friction coefficient in the contact area with the belt-shaped photosensitive member may be increased.

[0031]

In the photoconductor unit according to claim 1, the belt-like photoconductor according to claim 2 and the driving means according to claim 3 which constitute the photoconductor unit, the belt-like photoconductor is configured to be reversible in the forward and reverse directions,
Since the processing for increasing the friction coefficient in the contact area between the belt-shaped photoconductor and the drive means is performed, it is possible to prevent the slip between the photoconductor belt and the drive means when the rotation direction of the photoconductor belt is switched. Becomes

[Brief description of drawings]

FIG. 1 is a schematic view of an image forming apparatus capable of double-sided copying and composite copying, to which a photoconductor unit according to the present invention is attached.

FIG. 2 is an enlarged schematic diagram of an image forming unit of the image forming apparatus in FIG.

[Explanation of symbols]

 201 driving roller 202 driven roller 203 photoconductor 208 developing device 312 transfer belt 313 transfer charger

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuhiko Saito 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Co., Ltd. (72) Yukitaka Nakazato 1-3-6 Nakamagome, Ota-ku, Tokyo Share Company Ricoh

Claims (3)

[Claims] 1. A photoconductor unit for an image forming apparatus, comprising a belt-shaped photoconductor that can be rotated in the normal and reverse directions, and a drive unit that stretches and drives the belt-shaped photoconductor. A photoconductor unit, which is subjected to a treatment for increasing a friction coefficient of a contact region. 2. A belt-shaped photoreceptor comprising a first layer made of an elastic member and a second layer made of a photoconductor on which image information is written. 3. A photoconductor driving means, wherein a plurality of protrusions are formed on a surface in contact with the belt-shaped photoconductor, and the photoconductor driving means rotates the photoconductor in both directions.