JPH0588472A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a double side copying device having high productivity in making a double-side copy and also capable of making a synthetic copy by arranging plural number of process units effectively into a space-reduced space in the device, restraining enlargement and complication of the whole device in spite of an arrangement of the plural number of process units, and maintaining easy process control. CONSTITUTION:In an image forming device having a photosensitive body 203 rotatable in both reciprocal directions, two exposure positions to form an electrostatic latent image on the photosensitive body 203, a single cleaning means 206 arranged between the two exposure positions so as to remove residual toner from the photosensitive body 203 after transfer is carried out by rotating reciprocally according to the rotational direction of the photosensitive body 203 and a single transfer means 313 to transfer image information on the visibly imaged photosensitive body 203 to a recording sheet, are arranged around the photosensitive body.

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, a facsimile or a laser printer which uses an electrostatic recording process. The present invention relates to an image forming apparatus capable of double-sided copying for recording, or an image forming apparatus capable of composite copying capable of recording a plurality of image information on one side of one recording sheet.

[0002]

2. Description of the Related Art Regarding an apparatus for performing double-sided copying on a recording sheet, for example, a recording sheet, one side of which has been copied, is disclosed in U.S. Pat. No. 4,098,551 and Japanese Patent Laid-Open No. 60-8863. There is generally known a mechanism in which a sheet is first stacked on an intermediate tray via a reversing mechanism and then fed again to a transfer section via a sheet feeding resist section. 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, so that it is further popularized. It is considered to be the copy form to be achieved. Therefore, it can be said that solving the above-mentioned "low copy productivity" is a social demand.

[0005]

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

Based on the above social demands, the present invention aims to provide a double-sided copying apparatus which has a structure different from that of the above-mentioned double-sided copying apparatus and which has high productivity and is capable of composite copying. Space saving of process units, efficient arrangement in the internal space of the device, increase in size and complexity of the entire device in spite of the arrangement of multiple process units, and easy process control retention This is an issue.

[0007]

SUMMARY OF THE INVENTION The present invention has the above-mentioned objects.
An object of the present invention is to provide an image forming apparatus having a photoconductor that can rotate in both forward and reverse directions. The photoconductor is provided between two exposure positions for forming an electrostatic latent image on the photoconductor, and the photoconductor. One cleaning unit that removes the residual toner after transfer from the photoconductor by reversing forward and backward according to the rotation direction of the photoconductor, and one transfer that transfers the image information on the photoconductor that has been visualized to the recording sheet. The solution is to arrange the means around the photoreceptor.

It is preferable that two charging means for charging the photoconductor and two developing means for visualizing the electrostatic latent image on the photoconductor be further arranged around the photoconductor.

Further, it is preferable to dispose at least one of the two erasing means and the two static eliminating means around the photosensitive member.

It is more preferable that the erase means or the charge eliminating means is also used as the pre-transfer charge eliminating means.

It is convenient to set the distances from the cleaning position on the photoconductor to the transfer position at the time of forward rotation and the reverse rotation of the photoconductor to be equal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in the drawings.

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

A cleaning unit 206 is installed facing the top of the photoconductor belt 203. The mag roller 216 and the bias roller 21 of the cleaning unit 206 shown in FIG.
The 7 can also rotate both forward and backward.

The transfer charger 313 that can move up and down is
It is provided inside the transfer belt 312, at a position facing the lowermost portion of the photoconductor belt 203, and when the recording sheet conveyed by the transfer belt 312 reaches the transfer position, the transfer charger 313 and this casing are provided. Transfer guide 3
28 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 adapted to be switched as necessary, and the transfer process is performed at this position during both forward and reverse rotations.

The photoreceptor belt 20 is provided as another unit for performing the image forming process, which is necessary for the electrophotographic process.
Surrounding 3 are two chargers 204A, 204B, two exposure positions, two developers 208A, 208B, two erasers 20.
5A, 205B, two static elimination lamps 207A, 207B, and two pre-transfer static elimination lamps 209A, 209B are installed. Each of the two units installed in this way has a symmetrical positional relationship with the line connecting the cleaning unit and the developing unit as a boundary in order to obtain the same process conditions when the photoconductor belt 203 rotates in the forward and reverse directions. It is arranged. By changing the arrangement, it is possible to arrange only one of the two erasers or the two static elimination lamps around the photoconductor 203, or to use the eraser or the static elimination lamp as a pre-transfer static elimination lamp. ..

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 rotation of the drive roller 201 in the direction of the arrow c is followed, the surface of the photoconductor belt 203 is uniformly minus by the charging charger 204A. Given an electric charge. Then, 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 that occupies the upper portion of FIG. 1, and an electrostatic latent image is formed on the surface of the photosensitive belt 203. 205A removes the charging potential of the non-image area.

Toner is adhered to the electrostatic latent image by the developing device 208A to form a visible image. Furthermore, the pre-transfer charge elimination lamp 209A performs charge elimination before transfer, and the photoconductor belt 20
The surface potential of 3 is lowered to prepare for the transfer process.

When the visible image on the photoconductor belt 203 reaches the transfer position, it is electrostatically adsorbed to the transfer belt 312,
The recording sheet synchronized by the first registration sensor 326 attached to the sheet is conveyed to the transfer position from the right side in the figure. Then, the transfer charger 313 and the transfer guide 328 provided in the casing move upward, and the photoconductor 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 when passing through the cleaning unit 206, and finally the charge removal lamp 207A removes the residual charge on the surface of the photoconductor belt 203, and the next copy. Prepared for a cycle.

FIG. 3 shows the structure of the cleaning unit 206 when performing the magbrush cleaning.

The rotation directions of the mag roller 216 and the bias roller 217 coincide with the rotation direction of the photosensitive belt 203. The transfer residual toner adhering to the photoconductor belt 203 is -35.
It is scraped off by the ears of the cleaning agent on the surface of the mag roller 216 applied to 0V. The toner collected by the mag roller 216 flies and adheres to the bias roller 217 by applying a voltage of −500 V to the bias roller adjacent thereto. Then, the toner on the surface of the bias roller 217 is
It is scraped off by the first blade 218 contacting in the counter direction, and is conveyed to the waste toner bottle by the conveying screw 220. Since the second blade 219 is attached so as to function as a counter blade when the bias roller 217 rotates in the reverse direction, when the bias roller 217 rotates in the normal direction, the contact pressure on the roller is small and the second blade 219 biases the roller. Even if it is in constant contact with the roller 217, there is no particular problem.
Rotate the adjuster fitted on the shaft of the D-shaped cut mag roller so that the main pole of the mag roller 216 is located about 6 ° downstream of the contact point with the photosensitive belt 203 in the rotation direction of the mag roller 216. , Both forward and reverse rotation are supported. It is also possible to use a fur brush instead of the mag roller. In this case, the transfer residual toner is scraped off and electrostatically adsorbed by the bristle tip of the fur brush.

During a series of copying cycles at the time of normal rotation of the photosensitive belt, the charging charger 204B and the eraser 205
B, the static elimination lamp 207B and the pre-transfer static elimination lamp 209B do not operate. The transfer device 208B 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 back side of the recording sheet having the front side transferred, that is,
When the drive roller 201 follows the rotation in the direction of the 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 It is the same as for normal rotation. First, the photoconductor belt 20
The surface of 3 is uniformly given a negative charge by the charger 204B. Then, the photoreceptor belt 203,
The exposure B guided from the optical system including the lens 106 performs slit exposure at the second exposure position to form an electrostatic latent image on the surface, and the eraser 205B removes the charging potential of the non-image portion.

Toner is adhered to the electrostatic latent image by the developing device 208B to form a visible image. Further, the pre-transfer charge erasing lamp 209B performs charge removal before transfer, and the photoconductor belt 20
The surface potential of 3 is lowered to prepare for the transfer process.

When the visible image on the photosensitive belt 203 reaches the transfer position, it passes through the fixing section 315 shown in the lower left part of the drawing of FIG. The recording sheet synchronized by the sensor 325 is conveyed to the transfer position from the left side in the figure. Then, the transfer charger 313 and the transfer guide 3 provided in the casing.
28 moves upward, the photoconductor belt 203 and the recording sheet are brought into close contact with each other, and transfer is performed. 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 328 are in a lowered state.

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

During a series of copying cycles when the above-mentioned photosensitive belt is rotated in the reverse direction, the charging charger 204A and the eraser 205
A, the static elimination lamp 207A and the pre-transfer static elimination lamp 209A do not operate. The transfer device 208A is retracted to a position where it does not contact the photoconductor belt 203.

It is also possible to rotate the photoreceptor belt 203 in the forward direction to copy the back side of the recording sheet having the front side transferred, and in that case, the recording sheet stored in the reversing section through the fixing section 315. Electrostatically attracted 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 are synchronized by the first registration sensor 326 attached to the belt 312, and the photosensitive belt Back side copying is performed according to the operation sequence during rotation.

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 conveyed to the reversing unit without being transferred is the second recording sheet. Synchronized by the registration sensor 325, electrostatically attracted to the transfer belt 312 that rotates clockwise in the figure, and transferred and transferred in the order of the operation during the reverse rotation. After the completion of the first transfer, the first registration sensor 326 synchronizes, and the reverse transfer conveys the composite transfer in accordance with the operation sequence during the forward rotation.

[0032]

According to the image forming apparatus of the first aspect of the present invention, there is provided a device for forming an electrostatic latent image on a photoconductor capable of rotating both forward and backward.
Provided between one exposure position and the two exposure positions,
One cleaning unit capable of rotating both forward and backward, which removes the residual toner after transfer from the photoconductor, and one transfer unit transferring the image information of the visible image on the photoconductor to the recording sheet are provided. The image forming apparatus according to claim 2, which is arranged around the photoconductor, further comprises two charging means for charging the photoconductor and two developing means for visualizing an electrostatic latent image on the photoconductor. Since both are placed around the photoconductor, it is possible to perform image formation during both forward and reverse rotations of the photoconductor, eliminating the need for a lengthy re-feeding path, and providing high productivity double-sided copying. An image forming apparatus capable of composite copying is realized.
In addition, depending on the arrangement state, it is possible to save space for a plurality of process units and efficiently arrange them in the space inside the apparatus, and to minimize the costly developing device,
In combination with the single transfer means, the size and complexity of the apparatus can be suppressed despite the high-productivity image forming apparatus capable of double-sided copying / synthetic copying. In this type of image forming apparatus, there are a plurality of process units having the same function, but since only one cleaning unit is installed, the space for one unit is sufficient. Unlike the unit described above, the unit can remain fixed and the contacting / separating operation is not required, so the mechanism and timing control are simplified. Since the drive roller of the photoconductor facing the unit works as a pressing member, it is not necessary to add a new member.

In the image forming apparatus of the third aspect, the distance from the cleaning position on the photoconductor to the transfer position at the time of normal rotation and reverse rotation of the photoconductor is set to be equal.
It is possible to provide a highly productive double-sided copy, and to provide an image forming apparatus in which the entire process control is easily performed by the forward and reverse rotation of the photoconductor.

[Brief description of drawings]

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

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

FIG. 3 is an enlarged schematic diagram of a cleaning unit of the image forming unit of FIG.

[Explanation of symbols]

 203 photoconductor belt 204A, 204B charging charger 206 cleaning means 208A, 208B developing device 312 transfer belt 313 transfer charger

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location G03G 15/16 7818-2H 21/00 111 6605-2H (72) Inventor Tatsuhiko Saito Ota Ward, Tokyo Nakamagome 1-3-6, Ricoh Co., Ltd. (72) Inventor Yukitaka Nakazato 1-3-6 Nakamagome, Ota-ku, Tokyo In-house Ricoh Co., Ltd. (72) Inventor Fumio Kurizumi 1 Nakamagome, Ota-ku, Tokyo 3-6, Ricoh Co., Ltd.

Claims (3)

[Claims] 1. An image forming apparatus having a photoconductor that can rotate both forward and backward, provided between two exposure positions for forming an electrostatic latent image on the photoconductor, and between the two exposure positions. One cleaning unit that removes residual toner after transfer from the photoconductor by rotating in the normal direction according to the rotation direction of the photoconductor and image information on the photoconductor that has been visualized is transferred to a recording sheet. An image forming apparatus, wherein one transfer unit is arranged around a photoconductor. 2. A charging means for charging the photoconductor and two developing means for visualizing an electrostatic latent image on the photoconductor are further arranged around the photoconductor. The image forming apparatus according to claim 1. 3. The image forming according to claim 1, wherein the distance from the cleaning position to the transfer position on the photoconductor is set to be equal when the photoconductor rotates in the normal direction and when the photoconductor rotates in the reverse direction. apparatus.