JPH0442272A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To reduce the change in the lapse of time of the electrical characteristic of an endless belt by providing a member to sweep out the surface of the endless belt with water when a material to be transferred carried being electrostatically attracted on the endless belt is pressed on a photosensitive material and toner electrified electrostatically held on the surface of the photosensitive material is transferred on the material to be transferred. CONSTITUTION:In the initializing operation of this device 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 2a, therefore, the surface of the endless belt 1 comes into contact with a roller 20 containing a water component and a roller 21 with high water- adsorptive quality. In such a state, the endless belt 1 and the rollers 20, 21 are driven, and the surface of the endless belt 1 is swept out with the water by the roller 20, and also, the water component remaining on the endless belt 1 is adsorbed with the roller 21, and an attached substance on the surface of the endless belt 1 can be eliminated by a series of such operations. Thereby, the change in the lapse of time of the electrical characteristic of the endless belt 1 can be moderated.

Description

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

[Background of the invention]

In electrophotographic printing devices, a transfer method using corona discharge has been used to transfer the toner image formed on the photoreceptor to the transfer target, but the transfer performance is poor in high humidity.
Further, it has the disadvantage that transfer defects tend to occur due to stains on the corona wire, wrinkles on the transfer target, and the like. As an alternative to this, it has been proposed to perform the transfer by charging a belt whose surface is made of a dielectric material and pressing the transfer object against the photoconductor with the belt, but in the above method, Transferability is largely influenced by changes in the electrical properties of the endless 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, and as a result, the electrical resistance and dielectric constant of the endless belt 1 change over time. This results in disadvantages such as a decrease in surface potential, a change in the amount of charge flowing into the transfer target, and a change 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 diagram showing changes over time in the surface potential of the endless belt.

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, reducing the belt surface potential. As shown, the potential of the belt is restored by removing foreign matter adhering to the surface by wiping with water.

From the above, we focused on the fact that changes in the electrical characteristics of the belt over time are caused by foreign matter adhering to the belt surface, and that foreign matter adhering to the surface can be removed by wiping with water. This design is designed to alleviate changes in the electrical characteristics of the belt over time and extend the life of the belt.

[Embodiments of the invention]

1 and 2 are cross-sectional views of a transfer device showing one embodiment of the present invention, and FIG. 3 is a perspective view thereof. This indicates when to wipe.

In the figure, the endless belt 1 is a side play 1-1011
is supported by a driving roller 2a, driven rollers 2b and 2c, and a tension roller luff, which are locked via bearings 13, and during printing operation, the tension roller 7 is pulled in the direction A by tension applying members 14 and 15. Therefore, the endless bell l-1 is applied with tension and is driven in the direction B by the driving roller 2a. When the paper 6 is supplied from a paper supply device (not shown) in the above state, the paper 6 is attracted to the endless belt 1 charged by the charging device 18 and conveyed. In the process in which the paper 6 is pressed against the drum 3, the paper 6
The image is transferred onto the image 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 driven 90 degrees, and the spring 16 is
Due to this action, the transfer device 17 rotates around the rotation axis of the quick-acting shaft 2a, and the endless belt 1- is released from the drum 3. This state is shown in FIG. 1 by a two-dot chain line.

Next, the operation of wiping the surface of the endless belt 1 with water will be explained with reference to FIG. The endless bells 1 to 1 rotate around the rotational axis of the shaft 2a, so that the surfaces of the endless bells 1 to 1 are brought into contact with the roller 2o containing moisture and the roller 21 made of a highly water-absorbing material. In this state, the endless belt 1 and the rollers 2 and 21 are moved, the surface of the endless belt l-1 is wiped with water by the rollers 20, and the moisture remaining on the endless belt 1- is adsorbed by the rollers 21. . Through the series of operations described above, deposits on the surface of the endless belt 1 are removed, thereby alleviating changes over time in the electrical characteristics of the endless belt.

Here, the roller 20 is a sponge impregnated with a small amount of water-absorbing glycol or the like, and the roller 21 is made of a highly water-absorbing cellulose sponge. The base layer of the endless belt 1 has a thickness of 0.3 m and an electrical resistance of 10'ΩG.
The surface layer is made of polyester with a thickness of 30 μm and an electrical resistance of 1016 Ω.The charging device 188 has a positive DC5K v, and the static eliminating device 19 has a C1
, OK v, a corona of 500 Hz is applied, and the feed speed of the bell l- is about 300 mm.

The roller 20 may be formed so that water is supplied from a separately provided water tank to the roller 2o as needed, without impregnating it with a small amount of glycol or the like.

〔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]

1-2 and 2 are cross-sectional views of a transfer device showing one embodiment of the present invention, FIG. 3 is a perspective view thereof, FIG. 4 is a cross-sectional view of a transfer device showing a conventional example, and FIG. FIG. 3 is an explanatory diagram showing the effects of the invention. In the figure, 1 is an endless belt, 2a is a drive roller, 2b
, 2c is a driven roller, 3 is a photoreceptor, 5 is 1-ner, 6 is a transferred body, and 20.21- is a water wiping member.

Claims (1)

[Claims] 1. Two or more rollers arranged parallel to each other in the axial direction, an endless belt supported by the rollers and partially or entirely made of a dielectric material, and the endless belt. The belt includes a charging member for charging the belt, and a photoreceptor disposed adjacent to the endless belt, and a transfer object that is electrostatically attracted to the endless belt and conveyed is pressed against the photoreceptor and the photoreceptor is charged. A printing device having a device for transferring electrostatically charged toner carried on a body surface to the transfer object, characterized in that the printing device includes a member for wiping the surface of the endless belt with water. 2. The electrophotographic printing apparatus according to claim 1, wherein the member for wiping the surface of the endless belt with water is configured to be able to come into contact with and separate from the surface of the endless belt. . 3. The member for wiping the surface of the endless belt with water is:
3. The electrophotographic printing apparatus according to claim 2, comprising a sponge-like member impregnated with a water-absorbing substance and a highly water-absorbing member. 4. The electrophotographic printing apparatus according to claim 1, wherein wiping the surface of the endless belt with water is performed during an initialization operation immediately after the electrophotographic printing apparatus is powered on. .