JPH0527612A - Transfer device - Google Patents

Abstract

PURPOSE:To remove the soiling of toner stuck to a transfer roller, and to control the rising of the temp. of the transfer roller by providing a vent means on the transfer roller and blowing out air to the surface of a roller. CONSTITUTION:The transfer roller is composed of a core metal 16 having a large number of air holes 15 on the surface and a hollow part 160 communicated with the air holes 15, and a roller surface layer 17 made of a conductive porous material on the core metal 16. A transfer bias is applied to one end of the core metal 16 via an electrode 18, to perform a transfer, and the other end of the core metal 16 is connected to an air supplying device A. In other words, the air (a) sucked from a pump 20 is exhausted from the inside of the transfer roller core metal 16 to the roller surface layer 17 through the air holes 15, and blown out from the large number of the holes of the surface layer 17 to the roller surface.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, a toner image formed on a toner image carrier such as a photoconductor is transferred onto a transfer material by a transfer device. Transfer devices that have been proposed and put into practical use include a corona transfer system and a roller transfer system. Recently, the transfer roller method has been reconsidered in terms of lower ozone, less transfer deviation, and less scattering.

FIG. 2 is an explanatory view of an example of an electrophotographic copying machine using a conventional general transfer roller. In this copying machine, the photoconductor 1 is charged by the charging roller 2 and exposed by the exposure unit 3 by an optical system (not shown) to form an electrostatic latent image. This latent image is developed by the developing unit 4. On the other hand, the transfer sheet S sent out from the sheet feeding cassette 9 by the action of the separating roller 10 and the separating plate 11 reaches the timing roller 12, and from there, is sent to the transfer section in synchronization with the toner image on the photoconductor, and thus, The toner image is transferred onto the transfer paper S by the transfer roller 5. At this time, a bias having a polarity opposite to that of the toner is applied to the transfer roller 5 from the power source V. The transfer sheet S is separated from the photoconductor 1 by its own stiffness, is discharged by the discharging needle 6 and is guided by the guide 13, and the fixing device 1
After the toner image is fixed at 5, it is ejected to the outside of the machine.

The photoconductor 1 is cleaned of residual toner by the cleaner 7, erased of residual charge by the eraser 8, and repeats the same process again.

[0005]

In this case, since the transfer roller 5 is always in contact with the photoconductor 1, the fog toner on the photoconductor 1 in the non-image area adheres to the transfer roller 5. Further, when the feeding fails, the toner image may adhere to the transfer roller. The toner thus adhered causes the back stain of the next transfer paper, and causes transfer failure, paper passing failure, and the like.

[0006] Conventionally, as a method of cleaning the transfer roller dirt, there is known a cleaning method in which the polarity of the bias voltage of the transfer roller is reversed at the time of non-transfer and the toner adhering to the transfer roller is returned to the photosensitive member. There is. However, in this method, when the bias voltage of the transfer roller is switched from the polarity at the time of transfer to the opposite polarity, a large amount of toner is returned to the photoconductor side in a short period of time, so the cleaner of the photoconductor becomes overloaded, Insufficient cleaning of the photoconductor tends to occur. Therefore, generally, the transfer roller is cleaned by bringing a brush or a blade into contact with the transfer roller.

By the way, in a device which can perform double-sided copying (printing) or composite copying (printing), when double-sided copying (printing) or composite copying (printing) is continuously performed, the transfer paper passes through the fixing device once. Since it repeatedly passes through the transfer roller while the temperature is high, the surface temperature of the transfer roller is increased. When the surface temperature of the transfer roller rises, the viscoelastic property of the toner attached to the transfer roller changes, and complete cleaning by the brush or blade is not performed, and as a result,
The back surface of the transfer material may be soiled, or in the worst case, JAM may occur.

Further, as an adverse effect when continuous double-sided copying (printing) or composite copying (printing) is performed by an electrophotographic apparatus using a transfer roller, there is a change in sensitivity due to a temperature rise of a photoconductor. This is because the use of the transfer roller improves the adhesion between the transfer material and the photoconductor. When the sensitivity of the photoconductor changes, the charging potential of the charging device fluctuates, which leads to defective images.

Accordingly, the present invention provides a transfer device using a transfer roller, which can remove toner stains adhering to the transfer roller and at the same time cool the transfer roller to suppress its temperature rise. With the goal.

[0010]

According to the present invention, in accordance with the above-mentioned object, in a transfer device using a transfer roller, the transfer roller is provided in a cored bar having a hollow portion and a ventilation hole communicating from the hollow portion to the surface. A transfer device is provided which surrounds a porous material and which is provided with an air supply means for blowing air into the hollow portion of the core metal to blow out the roller surface from the hole of the porous material layer. Is.

[0011]

According to the transfer apparatus of the present invention, the transfer material is passed between the toner image carrier and the transfer roller of the image forming apparatus, and the transfer bias is applied to the transfer roller from the transfer power source as in the conventional case. The toner image on the image carrier is transferred to the transfer material. Further, by blowing air from the air feeding means into the hollow core of the transfer roller, the air is blown from the ventilation holes of the core through the holes of the porous material layer to the roller surface,
While removing toner stains on the roller surface,
Cool the roller surface.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of one embodiment. This transfer device 5
Reference numeral 0 has a transfer roller 51 and an air supply device A. The transfer roller 51 has a large number of vent holes 15 on its surface, and a hollow core metal 16 having a hollow portion 160 communicating with the holes, and a conductive porous (open-cell) material surrounded by the core metal 16. And a roller surface layer 17 formed by the above. A transfer bias can be applied to the transfer roller 51 from one end of the cored bar 16 via the electrode 18, and a normal transfer process can be performed while being driven by the photosensitive drum of the image forming apparatus.

The other end of the cored bar 16 is connected to the air supply device A via a docking portion (rotary joint) 19. That is, the hollow portion 160 of the core metal 16
Communicate with an air inflow path 21 having a pump 20 for inflowing air. The air a sucked from the outside by the pump 20 follows the path shown by the arrow in FIG.
The transfer roller core 160 is discharged from the inside 160 to the roller surface layer 17 through the core hole 15, and is further blown out to the roller surface from a large number of holes in the surface layer.

In the above structure, the toner adhering to the transfer roller 51 due to the image formation is blown off and cleaned by the discharging force of the air. As a result, it is possible to prevent problems such as stains on the back of the transfer paper. Since this transfer device cleans the surface of the transfer roller 51 by aerodynamic force, it is also possible to remove so-called reversely charged toner that could not be completely removed by the conventional reverse bias application method.

Further, the inflow of the air can be always carried out during the image forming operation (it may be carried out during the stoppage), so that the paper which has become hot after passing through the fixing device is contacted at the time of double-side copying. Even if the temperature of the photoconductor and the transfer roller rises due to such a situation, both of them can be cooled by the air flow to keep them in a stable use state. The present invention can be applied to both a negatively charged photoreceptor and a positively charged photoreceptor. The present invention can be applied regardless of what is called regular development or reversal development. Furthermore, the transfer material can be applied to other than normal paper such as OHP paper.

[0016]

As described above, according to the present invention, in a transfer device using a transfer roller, it is possible to remove toner stains adhering to the transfer roller and at the same time cool the transfer roller to suppress its temperature rise. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an example of a copying machine that employs a conventional transfer roller.

[Explanation of symbols]

 50 Transfer Device 51 Transfer Roller 15 Vent Hole 16 Core Bar 17 Roller Surface Layer of Porous Material 18 Electrode 19 Joint Part A Air Supply Device 20 Pump 21 Air Inflow Path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinobu Hara 2-3-13 Azuchi-cho, Chuo-ku, Osaka, Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Junichi Tamaki 2-chome, Azuchi-cho, Chuo-ku, Osaka No. 13 in Osaka Kokusai Building Minolta Camera Co., Ltd. (72) Inventor Yasuyuki Hiromoto 2-33 Azuchicho, Chuo-ku, Osaka City Osaka Kokusai Building Minolta Camera Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A transfer device using a transfer roller, comprising:
The transfer roller is formed by surrounding a porous material in a core metal having a hollow portion and a vent hole communicating from the hollow portion to the surface, and blowing air into the core metal hollow portion to form the porous material. A transfer device comprising an air supply unit for blowing the roller surface from the hole of the layer.