JPH10312122A - Transfer device in image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform, when transferring a toner image from a photoreceptor belt onto a recording medium by means of a transfer opposite-roller satisfactory transfer without causing toner to remain on the photoreceptor belt after the transfer. SOLUTION: The image forming device of an orthogonal transfer system transfers the toner image 7c onto the printing paper 9 in a direction orthogonal to the direction where the printing paper 9 is carried. In the device, prior to the forward/backward movement of the transfer opposite-roller 8, bias potential which is used only for the period of the forward movement of the transfer opposite-roller 8 is set so that the printing paper 9 has the opposite polarity of the toner image 7c held on the photoreceptor belt 1. This enables pressure transfer by the transfer opposite-roller 8 and the electrical attraction transfer of the toner image 7c by the printing paper 9 itself, and restricts unnecessary toner-image-disturbance in the backward movement of the transfer opposite- roller 8.

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 an electrophotographic copying machine or a laser printer, and more particularly to an image forming apparatus for transferring a toner image in a direction perpendicular to or parallel to a conveying direction of a recording medium such as paper. And a transfer device in the image forming apparatus.

[0002]

2. Description of the Related Art In the field of electrophotographic image forming apparatuses,
For example, a toner type, which is excellent in resolution and can form a clear image, such as a laser printer, is widely used.

As one of such toner-type image forming apparatuses, the applicant of the present invention has disclosed in Japanese Patent Application No. 7-328600 that a toner image carrier is moved while moving a toner image carrier in a direction perpendicular to a conveying direction of printing paper. An orthogonal transfer type image forming apparatus for transferring an image was proposed. In this transfer device, the toner image carrier is rubbed in a direction orthogonal to the transport direction of the printing paper, and the toner image is transferred step by step, so that the transfer device is optimal for miniaturization of a product.

FIG. 2 is a block diagram schematically showing a conventional general image forming apparatus of the orthogonal transfer system, and FIG. 3 is a perspective view schematically showing the image forming apparatus of FIG.

In FIG. 2, a photosensitive belt 1 is wound around rollers 2a and 2b which are driven to rotate by a motor (not shown) so as to run in the direction of arrow A shown in FIG. The photoreceptor belt 1 has a surface coated with an organic photoconductive material, and its traveling direction is orthogonal to the feeding direction of the printing paper 9 supplied onto the transfer plate 10 by the paper transport rollers. And, around the photoreceptor belt 1,
A charging device 5 for uniformly charging the photosensitive belt 1 and an exposing device 6 for irradiating a laser beam 6a to form an electrostatic latent image on the surface of the photosensitive belt 1 and a developing roller 7b for supplying toner are built-in. A developing unit 7 for pressing the toner 7a against the photoreceptor belt 1 and visualizing the toner 7a as a toner image 7c is arranged in order. Reference numeral 3 denotes a cleaning device for removing residual image toner after one transfer, and reference numeral 4 denotes a static eliminator for removing residual charges.

Further, at a position in the loop of the photoreceptor belt 1 facing the transfer plate 10, a transfer opposing roller 8 having an axis perpendicular to the running direction of the photoreceptor belt 1 is disposed.
The transfer opposing roller 8 is connected to a motor (not shown) to apply a certain tension to the photoreceptor belt 1 and, at the same time, rotate on the loop side surface of the photoreceptor belt 1 with the printing paper 9. The printing paper 9 can travel in a direction perpendicular to the paper feeding direction.

The operation of transferring the toner image 7c on the photosensitive belt 1 to the printing paper 9 in such a conventional transfer device is as follows.

When an image forming operation is instructed by the control unit of the image forming apparatus, the rollers 2a and 2b are rotated by the driving of the motor, and the photosensitive belt 1 starts running in the direction of arrow A in FIG. Then, the surface of the photoreceptor belt 1 is first charged by the charger 5 in accordance with the content of the image to be formed, and subsequently the charging potential is reduced by the laser beam 6a emitted from the exposure unit 6. Thereby, an electrostatic latent image is formed.

When the portion of the photosensitive belt 1 where the electrostatic latent image is formed reaches the developing device 7, the developing roller 7b of the developing device 7 is rotated by its driving means (not shown), and Abut As a result, while the photosensitive belt 1 moves while being nipped between the developing roller 7b and the roller 2a, the electrostatic latent image is developed by the toner 7a attached to the surface of the developing roller 7b. Toner image 7c
Is formed.

When the toner image 7c corresponding to a fraction of the size of the printing paper 9 is formed on the surface of the photoreceptor belt 1 by the above operation, the transfer opposing roller 8 is rotated by driving the motor. While moving in parallel along the printing paper 9. During the parallel movement of the transfer opposing roller 8, the photoreceptor belt 1 is sequentially pressed against the printing paper 9 by the transfer opposing roller 8, and the toner image 7 c on the photoreceptor belt 1 is printed on the printing paper 9.
Transcribed above.

After this transfer, the printing paper 9 is moved on the transfer plate 10 in the running direction of the photoreceptor belt 1 by a paper transport roller (not shown) which is arranged on the transport path of the printing paper 9 and is driven to rotate. Is transported to a predetermined position in a direction perpendicular to the direction.

[0012]

SUMMARY OF THE INVENTION In a conventional transfer device,
The transfer of the toner image 7c on the photoreceptor belt 1 to the printing paper 9 side simply uses the pressing force of the photoreceptor belt 1 against the printing paper 9 by the transfer opposing roller 8. That is,
The degree of adhesion of the toner image 7c to the printing paper 9 is determined substantially in proportion to the pressing force accompanying the movement of the transfer opposing roller 8, and by appropriately maintaining this pressing force, the toner remains on the photosensitive belt 1. Is preventing.

However, changes in conditions such as temperature and humidity,
Due to changes in various conditions such as insufficient tension applied to the photoreceptor belt 1 and occurrence of meandering, a part of the toner of the toner image 7c remains on the photoreceptor belt 1 side only by the pressing force by the transfer opposing roller 8. Inevitable. That is, if the fine powder toner before heating and melting is adhered to the printing paper 9 only by mechanical pressure, the deformation or bending of the photoreceptor belt 1 or the printing paper 9 itself may occur. The phenomenon that toner remains on the photoreceptor belt 1 after transfer is remarkable.

The problem to be solved in the present invention is that when a toner image is transferred from a photoreceptor belt onto a recording medium by a transfer opposing roller, good transfer is possible without toner remaining on the photoreceptor belt after the transfer. An object of the present invention is to provide a transfer device in an image forming apparatus.

[0015]

According to the present invention, a closed-loop photoreceptor belt provided as a toner image carrier is disposed so as to be able to run in a direction perpendicular to or parallel to a recording medium feeding direction so as to cut through the recording medium. A transfer device that transfers the carried toner image by continuously pressing the photosensitive belt onto the recording medium, wherein a loop of the photosensitive belt includes:
A transfer opposing roller that reciprocates in a direction to cut through the recording medium while pressing the photosensitive belt against the recording medium,
This is a system that sets the recording medium to a bias potential in accordance with the period of the outward movement of the transfer opposing roller.

According to such a configuration, the toner image can be transferred to the recording medium side not only by the pressing force against the photosensitive belt but also by the electric attraction force. Residual toner is prevented, and high-quality printing by stable transfer is enabled.

[0017]

According to the present invention, a closed loop photoreceptor belt provided as a toner image carrier is disposed so as to be able to run in a direction perpendicular to or parallel to a recording medium feeding direction in a direction to cut through the recording medium, A transfer device for transferring a carried toner image by continuously pressing a photoreceptor belt onto a recording medium, in a direction of cutting through the recording medium while pressing the photoreceptor belt against the recording medium in a loop of the photoreceptor belt. The transfer opposing roller reciprocates in the direction of the forward path of the transfer opposing roller, and the recording medium is set at a bias potential in accordance with the forward path operation. The toner image can be transferred by the electric attraction force by the bias to the recording medium having the opposite polarity to the image, and the bias voltage is applied in the return path of the transfer opposing roller. Eliminating the adsorption of the toner image at backward by so as not to apply a has the effect of suppressing the occurrence of deviation of the image.

Hereinafter, embodiments of the present invention will be described. FIG. 1 is a schematic view of a transfer device of an orthogonal transfer system according to an embodiment of the present invention as viewed in a sheet conveying direction. In the configuration of the transfer device, the same members as those of the conventional example shown in FIGS. 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

The timing of the movement of the photosensitive belt 1 and the feeding of the printing paper 9 are exactly the same as those in the conventional example, and the portion charged by the charger 5 is irradiated with the laser beam 6a by the exposure device 6 to emit laser light 6a. After an electrostatic latent image is formed on the surface of the photoreceptor belt 1, the toner 7a is rubbed by the developing device 7 to form a toner image 7c. At this time, since the photosensitive belt 1 is negatively charged with a negative potential by the charger 5, the toner image 7c formed on the surface thereof is also negatively charged.

After or concurrently with the development process described above, the printing paper 9 is supplied to the upper surface of the transfer plate 10. The feeding direction of the printing paper 9 is orthogonal to the running direction of the photosensitive belt 1 as described above. Before the printing paper 9 is supplied onto the transfer plate 10, the photosensitive belt 1 does not interfere with the transfer plate 10 and the pressing operation by the transfer opposing roller 8 is performed as shown by the solid line in FIG. The transfer opposing roller 8 is made to stand by at a position shown in the drawing so that the process can be performed. That is, since the transfer opposing roller 8 is arranged so as to perform a reciprocating stroke operation between the standby position and the dashed line in the drawing in one transfer operation, it is always set to the standby position at the beginning of the transfer process. .

When the transfer opposing roller 8 moves from the position shown by the solid line to the position shown by the broken line in the figure, the transfer opposing roller 8 applies a pressing force to the printing paper 9 on the transfer plate 10, so that the photosensitive belt 1 Is transferred onto the printing paper 9.

In the transfer using only the pressing force by the transfer opposing roller 8, as described in the section of the prior art, if the pressing force is insufficient for some reason, the toner image 7c is printed on the printing paper 9. Transfer to the photosensitive member belt 1 becomes insufficient, and a part of the toner image 7c remains on the photoreceptor belt 1.

Therefore, in the present embodiment, when the toner image 7c is transferred to the printing paper 9 by the reciprocating operation of the transfer opposing roller 8, the printing paper 9 Transfer plate 1 below
0 is connected to a bias power supply 11 for applying a bias voltage having a polarity opposite to the charging polarity of the toner image 7c.

By providing such a bias power source 11, when the transfer opposing roller 8 starts the transfer operation, the bias voltage has already been applied to the printing paper 9 by the bias power source 11 in the opposite polarity to the toner of the toner image 7c. Therefore, the toner image 7c can be electrically attracted to the printing paper 9. Therefore, the transfer of the toner image 7c to the printing paper 9 is not only performed by the pressing force of the transfer facing roller 8, but also by the electric attraction force of the printing paper 9, so that the pressing force of the transfer facing roller 8 becomes insufficient. Also, the electric attraction force compensates for this, and the toner image 7c can be transferred onto the printing paper 9 satisfactorily without remaining on the photosensitive belt 1.

When the transfer opposing roller 8 reaches the stroke end indicated by the broken line in the drawing, the movement is reversed and the roller is returned to the origin position. When the transfer opposing roller 8 returns, the application of the bias voltage from the bias power supply 11 to the transfer plate 10 is stopped, and the transfer opposing roller 8 is moved to the standby position. Thereafter, by repeating the same operation, the transfer of the toner image onto one print sheet 9 is completed.

Here, the application of the bias voltage to the transfer plate 10 is performed not during the forward path of the transfer opposing roller 8 but during the return path, so that the toner image 7 remaining on the photosensitive belt 1 can be obtained.
It is possible to electrically attract c to the printing paper 9 side. That is, in the forward path of the transfer opposing roller 8, the transfer is performed only by the pressing force, and in the backward path, the toner remaining on the photosensitive belt 1 side is electrically attracted to the printing paper 9 by
The toner remaining on the photosensitive belt 1 is prevented.

However, in such an operation of applying a bias voltage on the return path, the photosensitive belt 1
Removes the toner remaining on the photosensitive belt 1
Since the transfer is performed so that no toner remains on the upper portion, the transfer is performed twice. For this reason, there is a possibility that a difference occurs between the image transferred on the forward path and the image transferred on the return path, and the deterioration of the quality of the printed image cannot be ignored. Therefore, only during the forward stroke of the transfer opposing roller 8 is the transfer plate 10
It can be said that it is optimal to bias the paper to the opposite polarity to the toner image 7c by applying a bias voltage to the sheet.

As described above, in the present embodiment, when the toner image 7c is transferred to the printing paper 9 by the reciprocating operation of the transfer opposing roller 8, the transfer plate 10 below the printing paper 9 is formed only on the outward path of the reciprocating operation. By applying a bias having a polarity opposite to the charging polarity of the toner, it is possible to prevent a part of the toner from remaining on the photosensitive belt 1.

In the above example, the printing paper 9 is conveyed in a direction perpendicular to the running direction of the photosensitive belt 1. However, in the case of the so-called parallel transfer type, the bias voltage is applied only during the outward path of the transfer opposing roller 8. It is also possible to apply the voltage. That is, in FIG. 1, the printing paper 9 is conveyed in the direction indicated by the one-dot chain line arrow in the drawing, and is configured to coincide with the running direction of the photosensitive belt 1 and the forward direction of the transfer opposing roller 8.

As described above, even in the parallel transfer method, when the toner image 7c is transferred to the printing paper 9 by the reciprocating operation of the transfer opposing roller 8, the transfer image is transferred to the transfer plate 10 under the printing paper 9 only in the forward path of the reciprocating operation. By applying a bias having a polarity opposite to the charging polarity of the toner, it is possible to prevent a part of the toner from remaining on the photosensitive belt 1.

[0031]

According to the present invention, in addition to the transfer of the toner image by only the pressing force, the toner image is transferred by the electric attraction force by the bias to the recording medium having the opposite polarity to the toner image. It is possible to prevent the toner from remaining on the body belt side, and to prevent the toner image from being attracted on the return path by preventing the bias from being applied on the return path, thereby suppressing the occurrence of image shift. It is possible to optimize both aspects of maintaining high image quality.

[Brief description of the drawings]

FIG. 1 is a schematic view of a transfer device of an orthogonal transfer system according to an embodiment of the present invention as viewed in a sheet conveyance direction.

FIG. 2 is a configuration diagram schematically showing a conventional general orthogonal transfer type image forming apparatus.

FIG. 3 is a perspective view schematically showing the image forming apparatus of FIG. 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2 a, 2 b roller 3 cleaning device 4 static eliminator 5 charger 6 exposure device 6 a laser beam 7 developing device 7 a toner 7 b developing roller 7 c toner image 8 transfer opposing roller 9 printing paper 10 transfer plate

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Yasunori Sagara 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Koji Migita 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] A closed-loop photoreceptor belt provided as a toner image carrier is disposed so as to be able to travel in a direction perpendicular to or parallel to a recording medium feeding direction in a direction to cut through the recording medium, and to carry the toner image carried thereon. A transfer device for transferring by continuously pressing a body belt onto a recording medium, wherein a transfer opposing reciprocatingly moves in a direction to cut through the recording medium while pressing the photosensitive belt against the recording medium in a loop of the photosensitive belt. A transfer device in an image forming apparatus, comprising: a roller; and a system for setting a recording medium to a bias potential according to a period of a forward movement of a transfer opposing roller.