JPH11119565A - Transfer device - Google Patents

Abstract

(57) [Problem] To provide a transfer device capable of suppressing ozone generation and preventing omission during transfer with a simple configuration. A transfer device according to the present invention includes a transfer belt and a drive roller for driving the transfer belt.
The transfer belt 9 is constituted by forming a rigid thin film sheet into an endless shape, and one side of the transfer belt 9 supports the transfer material 17 at a transfer position where the transfer material 17 faces the photosensitive drum 1. The drive roller 11 is inserted at a position away from the photosensitive drum 1 on the side. Since the transfer belt 9 presses the photosensitive drum 1 only with its rigidity, the pressing force with which the transfer belt 9 presses the photosensitive drum 1 is small. In addition, since corona discharge is not used, the amount of discharge in air is small, and generation of ozone is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for transferring a toner image formed on an image carrier to a sheet in an image forming apparatus such as a printer or a copying machine.

[0002]

2. Description of the Related Art Generally, in a copying machine, as a method of transferring a toner image formed on a photosensitive drum to a sheet, a corona wire is installed near a position where the photosensitive drum and the sheet face each other, and a corona wire is provided. A method is known in which a toner image is transferred to a sheet by applying a bias (transfer bias) having a polarity opposite to that of the toner by corona discharge and attracting the toner to the sheet.

As disclosed in JP-A-3-50562, a method of transferring a toner image onto a sheet by bringing a transfer roller into contact with a photosensitive drum and applying a bias to the transfer roller is disclosed. JP-A-3-1346
As disclosed in Japanese Patent Publication No. 88-88, a method is known in which a transfer belt is suspended between two rollers and a transfer is performed by applying a bias to the transfer belt.

Further, as disclosed in Japanese Patent Application Laid-Open No. 6-67553, there is an apparatus in which a cylindrical thin film sheet is placed on the outer periphery of a transfer roller, and the transfer roller is pressed against the photosensitive member via the thin film sheet.

[0005]

However, in the case of the above-described technique of transferring by corona discharge, a corona wire is used.
Since it is separated from the photoreceptor drum and the paper, it discharges into the air when a bias is applied. Therefore, the discharge amount is large and a large amount of ozone is generated, which is not preferable.

In the case of the technique in which the transfer roller is brought into contact with the photosensitive drum, a bias can be applied directly, so that the discharge amount is suppressed and the amount of ozone generated is small, but the transfer roller presses the photosensitive drum. As a result, there is a problem in that the attached toner is displaced or collapsed, so that the toner comes off and cannot be transferred to a portion to which the toner should be transferred, that is, so-called missing during transfer is likely to occur.

[0007] In the case of the transfer technique using a transfer belt, the transfer belt in contact with the photosensitive drum has less contact pressure than the transfer roller, so that there is little omission during transfer, but the transfer belt is suspended between a plurality of rollers. However, there is a problem that the device becomes large.

Further, in the case of a transfer device in which a transfer roller and a thin film sheet are combined, the transfer roller is pressed against the photosensitive drum, so that it is not possible to sufficiently prevent omission during transfer due to the pressing force.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer apparatus which can suppress generation of ozone and can prevent omission during transfer with a simple configuration.

[0010]

According to a first aspect of the present invention, there is provided a transfer belt for transferring a toner image carried on an image carrier to a transfer material, and a single drive roller for driving the transfer belt. A transfer device, wherein the transfer belt is formed by forming a rigid thin film sheet into an endless shape, and one side of the transfer belt supports the transfer material at a transfer position where the transfer material faces an image carrier; The drive roller is inserted into the other side of the transfer belt at a position away from the body.

According to the first aspect of the present invention, the drive roller is separated from the transfer position where the toner image is transferred, and the drive roller does not directly press the photosensitive drum. As a result, the pressure at which the transfer belt presses the photosensitive drum at the transfer position where the toner image is transferred to the paper is reduced. Therefore, it is less likely that a dropout during transfer due to this pressing force will occur. In addition, since corona discharge is not used, the amount of discharge in air is small, and generation of ozone is suppressed.

The invention according to a second aspect is characterized in that a guide member for guiding the trajectory of the transfer belt is provided.

According to the second aspect of the present invention, by providing the guide member, the trajectory of the transfer belt can be stabilized, and the transfer of the transfer material can be stabilized.

According to a third aspect of the present invention, a cleaning member is provided on the other side of the transfer belt for removing toner by contacting the surface of the transfer belt.

According to the third aspect of the present invention, by providing the cleaning member in contact with the transfer belt, residual toner adhered to the transfer belt can be removed, so that the transfer of dirt to the back side of the transfer material can be prevented.

According to a fourth aspect of the present invention, the drive roller includes electrodes, and the transfer belt is made of a conductive material, and a transfer bias is superimposed on the transfer belt by the drive roller.

According to the fourth aspect of the present invention, the transfer belt is made of a conductive material, the drive roller is provided with electrodes, and a bias can be directly applied to the transfer belt. Become simple.

According to a fifth aspect of the present invention, the transfer belt is made of an insulating material, an electrode is provided inside the transfer belt at a transfer position, and a transfer bias is superimposed at the transfer position. I do.

According to the fifth aspect of the present invention, the transfer belt is made of an insulating material, and the inner side of the transfer belt is
By applying a bias to the transfer belt, the bias is superimposed on the transfer surface of the transfer belt that is in contact with the transfer material, and the transfer material is attracted by static electricity. Thereby, the transfer force of the transfer material is improved.

According to a sixth aspect of the present invention, a bias having a polarity opposite to that of the transfer bias is superimposed on the driving roller.

According to the sixth aspect of the present invention, since a bias having the same polarity as the toner is applied from the electrode of the drive roller, the residual toner adhered to the drive roller is easily separated by the repulsive force between the same polarity. This makes it easier to remove residual toner. Further, the bias of the transfer material is improved by the bias superimposed on the transfer belt.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below using a copying machine as an example. FIG. 1 is a sectional view of a part of the copying machine. The copying machine is provided with a photosensitive drum 1, and a separation electrode 2, a cleaning device 3, a charging device 5, and a developing device 7 are provided around the photosensitive drum in a clockwise direction.
They are arranged in this order.

A transfer device 4 is disposed below the photosensitive drum 1, and the transfer device 4 includes a transfer belt 9 and one drive roller 11. The transfer belt 9 and the drive roller 11 have a length substantially equal to the axial length of the photosensitive drum 1.

The transfer belt 9 has an endless oval cross section, and the oval extends obliquely downward from the lower surface of the photosensitive drum 1. On one side of the ellipse away from the photosensitive drum 1, a drive roller 11 is inserted in contact with the inside of the transfer belt 9. That is, the transfer belt 9
One drive roller 11 inserted in contact with the inside
Has been rotated by The transfer belt 9 extends obliquely upward from the drive roller 11 side.
On the other side, a transfer paper (hereinafter, referred to as a “transfer material”) 17 is provided on the surface on the lower end side of the photosensitive drum 1. That is, the transfer belt 9 is driven by only one drive roller 11, and is further pressed against the surface of the photosensitive drum 1 only by the rigidity of the transfer belt 9.

The transfer belt 9 is made of a rigid thin film sheet and has, for example, a thickness of 0.5 mm and a width of 300 to 300 mm.
It is made of 350 mm chloroprene rubber (PTFE) coated with polytetrafluoroethylene (PTEF) and is made endless.
The material of the thin film sheet is not particularly limited, for example,
Polyvinylidene fluoride (PVDF) may be used.

The transfer belt 9 and the driving roller 11 are supported by a holder 13 and a guide plate 15. Holder 13
Is installed diagonally below the photosensitive drum 1, has a depression 21 larger than the circumference of the drive roller 11, and has a width longer than at least the length of the drive roller 11. The drive roller side of the transfer belt 9 is housed in the recess 21. The upper surface of the holder 13 is configured to guide the transfer material 17 between the photosensitive drum 1 and the transfer belt 9.

The guide plate 15 is attached so as to extend from the side surface of the holder 13. The tip of the guide plate 15 extends halfway toward the photosensitive drum 1. The lower surface of the transfer belt 9 is guided by the guide plate 15 and extends toward the photosensitive drum 1. Transfer belt 9
Is guided by a protrusion 14 of the holder 13, and in the present embodiment, the protrusion 14 also serves as a guide plate.

Next, the operation of this embodiment will be described. The photoreceptor drum 1 rotates clockwise, and the transfer belt 9 rotates counterclockwise in contact with the photoreceptor drum 1. A transfer material 17 is fed between the photosensitive drum 1 and the transfer belt 9 and guided between the photosensitive drum 1 and the transfer belt 9,
It is designed to be transported. The outer peripheral surface of the photosensitive drum 1 is uniformly charged by the charging device 5. A light image such as light reflected from the document is projected on the charged surface, and the bias of the portion is attenuated to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 1 becomes a toner image developed by developing the toner by the developing device 7. This toner image is transferred onto the transfer material 17 supported on the transfer belt 9. The transfer material 17 to which the toner image has been transferred is separated from the photosensitive drum 1 by the separation electrode 2, and then fixed by a fixing device and discharged.

On the other hand, the transfer belt 9 is rotationally driven by applying a drive torque only by one drive roller 11 inserted into one side of the transfer belt 9. On the other hand, the other side is guided by the guide plate 15 in the direction of the photosensitive drum 1 and comes into contact with the photosensitive drum 1. That is, since the transfer belt 9 is pressed against the photosensitive drum 1 only by its rigidity, the pressing force between the photosensitive drum 1 and the transfer belt 9 is extremely small. Therefore,
Due to the pressing force, the toner is less likely to be displaced or collapsed, and is less likely to be missing during the transfer. The driving roller 11
Since only one is required, the configuration is simple and the device is downsized. In addition, since corona discharge is not used, the amount of discharge in air is small and generation of ozone can be suppressed.

Next, other embodiments of the present invention will be described in order. In the description, members and portions having the same functions as the above-described members and portions are denoted by the same reference numerals, and description thereof is omitted. .

FIG. 2 shows a second embodiment. In the second embodiment, the cleaning member 19 is provided on the holder 13. The cleaning member 19 is provided so as to contact the transfer belt 9 at a position corresponding to the drive roller 11. Further, a toner waste port 25 is provided between the holder 13 and the guide plate 15 so as to discharge the toner scraped off by the cleaning member 19. still,
As a material of the cleaning member 19, a blade, felt, or the like is used.

In the second embodiment, when the residual toner on the surface of the photosensitive drum 1 adheres to the transfer belt 9 after the transfer, the residual toner adhered to the transfer belt 9 is removed by the cleaning member 19 by the toner disposal port. It is scraped off to 25 and removed. Therefore, since there is no residual toner on the transfer belt, it is possible to prevent the transfer material 17 from being stained on the back side where the transfer material 17 is not transferred.

A modification of the second embodiment will be described.
In this modification, the drive roller 11 has a function of a transfer electrode for applying a bias, and the transfer belt 9 is made of a conductive material that conducts electricity.

A bias is applied to the transfer belt 9 by the driving roller 11, and the bias is superimposed on the transfer belt 9. On the surface of the photosensitive drum 1, a toner image having a polarity opposite to the bias superimposed on the transfer belt 9 is formed. Accordingly, the toner image is attracted to the transfer belt 9 by the electrostatic attraction due to the attraction between the different poles, and adheres onto the transfer material 17 passing between the photosensitive drum 1 and the transfer belt 9 to perform the transfer. It is.

Since the driving roller 9 has the function of a transfer electrode, it is not necessary to separately provide a transfer electrode.
The configuration is simplified.

FIG. 3 shows a third embodiment. In the third embodiment, the transfer belt 9 is made of an insulating material, and the electrode 23 is installed at a position facing the photosensitive drum 1 inside the transfer belt 9. The drive roller 11 has a function of an electrode, and is configured to superimpose a bias having the same polarity as that of the toner.

A bias having a polarity opposite to that of the toner is applied to the transfer belt 9 by the electrode 23. The transfer belt 9 on which the bias is superimposed attracts the toner by the bias applied to the transfer belt and transfers the toner image to the transfer material 17. Thereafter, the transfer belt 9 moves toward the cleaning member 19 together with the residual toner. Since a bias having the same polarity as that of the toner is applied to the drive roller 11, the residual toner described above is separated from the transfer belt 9 by the repulsive force between the same polarity, that is, the electrostatic repulsive force, and is removed by the cleaning member 19. Is done.

When the transfer belt 9 is made of an insulating material, an electric charge is applied to a contact portion between the transfer belt 9 and the transfer material 17 by applying a bias from the electrode 23, and the static electricity attracts the transfer material 17. Therefore, the transfer force of the transfer material 17 is improved, and the transfer material 17 passes smoothly, thereby preventing the omission during transfer. Further, a bias having the same polarity as that of the toner is superimposed on the driving roller 11, and the repulsion of the same polarity is used, so that the residual toner is easily separated, and the cleaning effect by the cleaning device 19 is improved.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from its use. For example, in the first embodiment, the shape of the transfer belt 9 may be any shape as long as it can be moved to the transfer position of the photosensitive drum 1, and the transfer belt 9 may be configured to be substantially circular.

Since the cleaning member 19 only needs to contact the transfer belt 9, it can be installed at any position.
A similar effect is obtained.

[0041]

According to the first aspect of the present invention, since the transfer belt presses the photosensitive drum only by its rigidity, it is difficult for the transfer belt to drop out due to the pressing force. Further, since no corona discharge is used, generation of ozone is suppressed.

According to the second aspect of the present invention, the trajectory of the transfer belt can be stabilized by the guide member, and the transfer of the transfer material can be stabilized.

According to the third aspect of the present invention, by providing the cleaning member, residual toner adhered to the transfer belt can be removed, so that the transfer of dirt to the back side of the transfer material can be prevented.

According to the fourth aspect of the present invention, since the drive roller has electrodes, it is not necessary to separately provide electrodes, and the configuration is simplified.

According to the fifth aspect of the present invention, by applying a bias to the transfer belt from the electrode inside the transfer belt, the transfer force of the transfer material is improved.

According to the sixth aspect of the invention, the residual toner adhered to the drive roller is easily separated, and the residual toner is easily removed. Furthermore, by the electrode of the driving roller,
The superimposed bias improves the adsorbability of the transfer material.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a main part of a copying machine in a first embodiment.

FIG. 2 is a diagram schematically showing a configuration of a main part of a copying machine according to a second embodiment.

FIG. 3 is a diagram schematically showing a configuration of a main part of a copying machine according to a third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 4 transfer device 9 transfer belt 11 drive roller 13 holder 14 protrusion 15 guide plate 19 cleaning member 23 electrode

Claims (6)

[Claims] 1. A transfer device comprising: a transfer belt for transferring a toner image carried on an image carrier onto a transfer material; and one drive roller for driving the transfer belt, wherein the transfer belt has rigidity. The thin film sheet is configured to have an endless shape, one side of the transfer belt supports the transfer material at a transfer position where the transfer material faces the image carrier, and at a position apart from the image carrier, the other side of the transfer belt Wherein the drive roller is inserted therethrough. 2. The transfer device according to claim 1, further comprising a guide member for guiding a trajectory of the transfer belt. 3. The transfer device according to claim 1, further comprising a cleaning member on the other side of the transfer belt, the cleaning member being in contact with a surface of the transfer belt to remove toner. 4. The transfer roller according to claim 1, wherein the drive roller includes an electrode, the transfer belt is made of a conductive material, and a transfer bias is superimposed on the transfer belt by the drive roller. 2. The transfer device according to claim 1. 5. The transfer belt is made of an insulating material.
4. The transfer device according to claim 1, wherein an electrode is provided inside the transfer belt at the transfer position, and a transfer bias is superimposed at the transfer position. 6. The transfer roller according to claim 5, wherein a bias having a polarity opposite to that of the transfer bias is superimposed on the drive roller.
3. The transfer device according to 1.