JPH0442276A - Belt transfer device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To moderate the change in the lapse of time of the electrical characteristic of an endless belt by providing a cleaning member which comes in contact with and cleans the surface of the endless belt at a side confronting with an electrification member. CONSTITUTION:In the initializing operation of a printer immediately after the application of a power source, a cam 12 is driven by 90 deg. further from a stopping state, and a transfer device 17 is rotated around the rotary shaft of a driving shaft 4, and the surface of the endless belt 1 comes into contact with a roller 20 containing an abrasive material that is the cleaning member. The endless belt 1 and the roller 20 are driven in such state, and the surface of the endless belt 1 is polished with the roller 20. An attached substance on the surface of the endless belt 1 can be eliminated by a series of such operations. Thereby, it is possible to moderate the change in the laspe of time of the electrical characteristic of the endless belt 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a belt transfer device of an electrophotographic printing apparatus having a high performance transfer device.

[Background of the invention]

In an electrophotographic printing device, the l-
A transfer method using corona discharge has been used to transfer a toner image to a transfer target, but transfer performance is poor in high humidity, and transfer failures may occur due to stains on the corona wire or wrinkles on the transfer target. It had the disadvantage of being easy to use. As an alternative to this, it has been proposed to press the object to be transferred onto the photoreceptor with a belt made of a material with a volume resistance of 109 to 1014 ohms, and to perform the transfer by causing corona discharge to the pressing part. The above method is largely influenced by changes in the electrical characteristics of the transfer belt.

FIG. 4 is a sectional view showing an example of the prior art.

The endless belt 1 includes a driving roller 2a and driven rollers 2b, 2.
c, and in order to bring the transferred object 6 into close contact with the photoreceptor 3 by a tension roller rough, a predetermined tension is applied to press the transferred object 6 against the photoreceptor 3. The surface potential of the belt must be maintained appropriately to obtain proper transfer. However, on the surface of the endless belt 1, ionic substances generated during corona discharge by the charging device 18, dust in the air, etc. adhere to the surface of the endless belt 1, which causes the electrical resistance and dielectric constant of the endless belt 1-1 to decrease. This causes problems such as a decrease in surface potential due to aging, and a change in the amount of charge flowing into the transfer target, resulting in changes in transferability and paper conveyance.

In order to prevent the above-mentioned problems, the conventional technology has the disadvantage that the endless belt 1 must be replaced periodically at relatively short intervals.

[Purpose of the invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to reduce the change over time in the electrical properties of an endless belt.

[Summary of the invention]

FIG. 5 is a graph showing changes over time in the surface potential of the endless belt.

The solid line indicates the potential of a portion of the surface of the endless belt that is slightly and regularly polished, and the dotted line indicates the potential of a portion that is not polished.

It is known that ozone and NOx are generated during corona discharge, and it is thought that these ions and dust in the air adhere to the belt surface, causing the surface potential of bells 1 to 1 to decrease, as shown in the figure. As shown in the figure, the drop in belt potential can be alleviated by periodic slight polishing of the surface.

From the above, the present invention has determined that the change over time in the electrical characteristics of the belt is thought to be caused by foreign matter adhering to the surface of the belt 1 and deterioration of the surface film, and that the foreign matter adhering to the surface can be removed by slight polishing of the belt surface. By slightly polishing the surface of the belt periodically, the belt's electrical characteristics change over time, and the belt's lifespan is extended.

[Embodiments of the invention]

Figures 1 and 2 are schematic diagrams showing one embodiment of the present invention, and Figure 3 is a schematic diagram showing an embodiment of the present invention.
The figures are perspective views, with FIG. 1 showing the printer during printing and stopping, and FIG. 2 showing the printer during surface polishing.

In FIGS. 1 and 3, the endless belt 1 is supported by a driving roller 2a, driven rollers 2b, 2c, and a tension roller ruff, which are locked to a side plate 10.11 via a bearing 13, and is supported during printing operation. is tension roller 7
is pulled in the direction A by the tension applying members 14 and 15, so the endless belt 1 is applied with tension and is driven in the direction B by the drive roller 2a. When the paper 6 is fed from a paper feeder (not shown) in the above state, the toner 5 is transferred onto the paper 6 while being sandwiched between the paper 6, the photoreceptor 3 and the endless belt 1, and passing near the charging device 18. The image is transferred and guided to a fixing device (not shown) provided downstream of the transfer device 17.

When the printing operation is completed, the driving of the endless belt 1 is stopped, the cam 12 is moved 90', and the spring 16 is moved.
Due to this action, the transfer device 17 rotates around the rotation axis of the shaft 4, and the endless belt 1 is retracted from the photoreceptor 3. This state is shown in FIG. 1 by a two-dot chain line.

Next, the polishing operation of the surface of the endless belt 1 will be explained with reference to FIG.

In the initialization operation immediately after the printing device is powered on, the cam 12 is further driven 90 degrees from the stopped state, and the transfer device 17 rotates around the rotation axis of the shaft 4, so that the surface of the endless belt 1 contains abrasive. It contacts the roller 20. In this state, the endless belt 1 and the roller 20 are driven, and the surface of the endless belt 1 is polished by the roller 20.

Through the above-described series of operations, deposits on the surface of the endless belt 1 are removed, thereby alleviating the change in the electrical holding property of the endless belt 1 over time.

Here, the roller 20 is a sponge containing a small amount of abrasive.

The roller 2o is not a sponge containing a small amount of abrasive,
A roller having a cloth made of ultrafine fibers on its outer periphery may also be used.

In this case, polishing of the surface of the endless belt cannot be expected, but a cleaning effect on the surface of the endless belt can be expected because the deposits on the surface of the endless belt are captured and held in the ultrafine fibers.

〔Effect of the invention〕

According to the present invention, it is possible to remove deposits on the surface of the endless belt that impede maintenance of the potential of the endless belt to obtain normal transfer, so it is possible to alleviate changes in the potential of the endless belt over time, and to ensure stable transfer performance over a long period of time. A printing device having the following can be provided.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing an embodiment of the present invention, Figure 3 is a perspective view, Figure 4 is a schematic diagram showing a conventional example, and Figure 5 is an explanatory diagram showing the effects of the present invention. . In the figure, ]- is an endless belt, 2a is a drive roller, 2
b, 2C is a driven roller, 3 is a photoreceptor, 5 is 1~ner, 6
20 is a transfer member, and 20 is a polishing member or a cleaning member.

Claims (1)

[Claims] 1. Two or more rollers arranged parallel to each other in the axial direction, and a volume resistance supported by the rollers is 10^9
An endless belt having a resistance of ~10^1^4 Ωcm, a photoconductor disposed adjacent to the endless belt, and an endless belt disposed opposite to the photoconductor with the endless belt interposed therebetween are charged. an electrostatically charged toner, which presses a transferred object, which is electrostatically attracted to the endless belt and is conveyed, against the photoreceptor, and is carried on the surface of the photoreceptor; The electrophotographic printing apparatus has a cleaning member that comes into contact with a surface of the endless belt facing the charging member and cleans the surface. Belt transfer device. 2. The electrophotographic printing apparatus according to claim 1, wherein the cleaning member for cleaning the surface of the endless belt is configured to be detachable from the surface of the endless belt. 3. The electrophotographic printing apparatus according to claim 2, wherein the cleaning member that cleans the surface of the endless belt is a member that cleans the surface of the endless belt by slightly scraping the surface of the endless belt. belt transfer device.