JPH0442287A - Electrophotographic printing device - Google Patents

Abstract

PURPOSE:To prolong the service life of an endless belt by relaxing the electric characteristic change of the belt with the passage of time by adding a means to sweep the surface of the belt with water to the transfer part of the device. CONSTITUTION:A means 19 to sweep the surface of an endless belt 1 with water is added to the transfer part. Since a transfer device is rotated around the rotary shaft of a shaft 4 in an initialize operation just after a power source is turned on, a water sweeping member 19 containing moisture and a dry sweeping member 20 get contact with the surface of the endless belt 1. When driving the endless belt 1, water sweeping member 19 and dry sweeping member 20 in such a state, the surface of the endless belt 1 is swept with water by the water sweeping member 19, and the moisture remained on the endless belt 1 is adsorbed by the dry sweeping member 20. By this series operation, an object stuck on the surface of the endless belt 1 is removed. Thus, the service life of the endless belt 1 can be prolonged by relaxing the electric characteristic change of the belt 1 with the passage of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic printing apparatus, and more particularly to an improvement of a transfer section in this type of printing apparatus.

[Conventional technology]

Printing devices that use electrophotography have used a corona discharge transfer method to transfer the toner image formed on the photoreceptor to the transfer target, but the transfer performance is poor at high temperatures, and the corona wire This method has the disadvantage that transfer defects tend to occur due to dirt, wrinkles, etc. on the transfer target.

In addition, as an alternative method to the above, a volume resistivity of 109 to 10
A method has been proposed in which a belt made of a 14 Ωcm material is used to press the transfer object against a photoconductor and generate a corona discharge in the pressed area, but the transfer performance of this method is inferior to that of an endless belt. It is greatly influenced by changes in electrical characteristics.

To explain this in more detail, FIG. 4 is a longitudinal sectional view showing the internal structure of a conventional electrophotographic printing apparatus.

In FIG. 4, the endless belt 1 is stretched between the driving roller 2a and the driven rollers 2b and 2C, and it is necessary to bring the transferred object 6 into close contact with the photoreceptor 3 via the tension roller 7. A predetermined tension is applied to. Furthermore, in order to obtain normal transfer, the surface potential of the bell 1-1 must be maintained appropriately.

In FIG. 4, 5 is a toner, 8 is a cleaner unit] 7 is a charger, and 18 is a static eliminator.

[Problem to be solved by the invention]

However, according to the conventional electrophotographic printing apparatus shown in FIG. 4, ionic substances generated during corona discharge by the charger 17 and even dust in the air adhere to the surface of the endless belt 1. However, as a result, the electrical resistance and dielectric constant of the endless belt 1 change over time, the surface potential of the endless belt 1 decreases, and the amount of charge flowing into the transfer target 6 also changes, resulting in changes in transferability and paper transport side. This may cause inconveniences such as

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

An object of the present invention is to reduce the change in electrical characteristics over time of an endless belt that presses a transfer target against a photoreceptor and generates corona discharge in the suppressed portion to perform transfer, in order to eliminate the drawbacks of the prior art described above. An object of the present invention is to provide an electrophotographic printing device.

[Means to solve the problem]

The object is to provide two or more rollers arranged parallel to each other in the axial direction, and an endless bell 1- supported by the rollers and having a volume resistance of 109 to 10'4 Ωc+n.
The endless belt has a photoconductor disposed adjacent to the endless belt, and an endless belt charging member provided at a position opposite to the photoconductor with the endless belt I in between, and is electrostatically attracted to the endless belt. In the electrophotographic printing apparatus, the electrophotographic printing apparatus is equipped with means for pressing a transferred object against a photoreceptor and transferring electrostatically charged toner carried on the surface of the photoreceptor to the transfer object. This is achieved by providing a wet wiping member that wipes the surface of the belt facing the charging member with water.

[Effect]

FIG. 5 is a diagram illustrating the effect of the present invention, that is, a diagram showing a change over time in the endless belt surface potential.

It is known that ozone and NO are generated during corona discharge, and it is thought that these ions and dust in the air adhere to the surface of the endless belt, thereby reducing the surface potential of the bell h. As shown in FIG. 5, the potential of the belt is restored by removing foreign matter adhering to the surface by wiping with water.

As described above, changes in the electrical characteristics of an endless belt over time are caused by foreign matter adhering to the belt surface, and focusing on the fact that the foreign matter adhering to the surface can be removed by wiping with water, the present invention has developed an electrophotographic printing method. By adding a means for wiping the surface of the endless belt with water, which is attached to the transfer section of the apparatus, it is possible to alleviate changes in electrical characteristics of the belt over time and extend the life of the belt.

〔Example〕

Hereinafter, the present invention will be explained based on an embodiment shown in FIGS. 1 to 3. FIGS. 1 and 2 are both longitudinal cross-sectional views of the main parts of the device of the present invention, and FIG. 3 is the same main part. 1 is a perspective view of the unit, FIG. 1 shows the printing time and stoppage, and FIG. 2 shows the wiping with water.

In FIGS. 1 and 3, the endless belt 1 is supported by a driving roller 2a, which is locked to a side plate 10.11 via a bearing 13, driven rollers 2b, 2C, and a tension roller luff. During the printing operation, the tension roller 7 is pulled by the tension applying member 14.15 in the six directions indicated by the arrows in FIG. driven by

In this state, when a transfer object (paper) 6 is supplied from a paper feeder (not shown), the transfer object 6 is held between the photoreceptor 3 and the endless belt 1, and the transfer object 6 is held in the vicinity of the charger 17. In the process of passing, the toner 5 is transferred onto the transfer target 6, and transferred to the transfer device 9.
is guided to a fixing device (not shown) provided downstream.

When the printing operation is completed, the driving of the endless belt 1 is stopped, the cam 12 is moved by 90'1Ilu, and the transfer device 17 is rotated around the rotation axis of the shaft 4 by the action of the spring coil 6, so that the endless belt] - is separated from the photoreceptor 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.

In the initialization operation immediately after the printing device is powered on, the cam 12 is further moved by 90'ilK from the stopped state, and the transfer device 9 rotates around the rotation axis of the shaft 4, thereby causing moisture to be deposited on the surface of the endless bell I-1. The wet wiping member 19 containing the wiping member 19 and the dry wiping member 20 made of a highly water-absorbing material are in contact with each other, and when the endless belt 1, the wet wiping member 19, and the dry wiping member 20 are driven in this state, The surface of the endless belt 1 is wiped with water by a wet wiping member 19, and the moisture remaining on the endless belt 1 is adsorbed by a dry wiping member 20.

Through the series of operations described above, deposits on the surface of the endless belt 1 are removed, and thereby changes in the electrical characteristics of the endless belts 1 to 1 over time are also alleviated.

For example, the wet wiping member 19 may be a sponge impregnated with a small amount of water-absorbing glycol, and the dry wiping member 20 may be a highly water-absorbing cellulose sponge.

Furthermore, the wet wiping member 19 may be configured to supply water to the wet wiping member 19 as needed from a separately provided water tank without impregnating it with a small amount of glycol or the like.

Furthermore, both the wet wiping member 19 and the dry wiping member 20 can be members having any shape other than a roller shape, for example, a pad shape.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the explanation of the illustrated embodiments, according to the present invention, the transfer target is pressed against the photoreceptor and a corona discharge is generated in this pressing portion to perform the transfer. Changes in the electrical characteristics of the belt over time are caused by foreign matter adhering to the belt surface, and focusing on the fact that the foreign matter adhering to the surface can be removed by wiping with water, the present invention provides a method for applying a method to the transfer section of an electrophotographic printing device. On the other hand, by adding a means for wiping the surface of the endless belt with water, changes in the electrical characteristics of the belt over time can be alleviated and the life of the belt can be extended.

That is, according to the present invention, it is possible to remove the impeding factors for obtaining normal transfer, in other words, the deposits on the belt surface that impede the maintenance of the endless belt's potential, so that it is possible to alleviate the change in the potential of the endless belt over time, and to maintain the endless belt's potential for a long time. An electrophotographic printing device having time-stable transferability can be provided.

[Brief explanation of the drawing]

1 to 3 show an embodiment of an electrophotographic printing apparatus according to the present invention, FIGS. 1 and 2 are longitudinal sectional views of the main parts thereof, and FIG. 3 is a perspective view of the main parts thereof. 4 are longitudinal sectional views showing the internal structure of a conventional electrophotographic printing apparatus, and FIG. 5 is a diagram illustrating the effects of the present invention. 1 is an endless belt, 2a is a continuous moving roller, 2b and 2c are driven rollers, 3 is a photoreceptor, 5 is a toner, 6 is a transfer object, 1
9 is a water wiping member.

Claims (1)

[Claims] 1. Two or more rollers arranged parallel to each other in the axial direction, and a roller with a volume resistance of 10, supported by the rollers.
An endless belt having a resistance of ^9 to 10^1^4 Ωcm, a photoreceptor disposed adjacent to the endless belt, and an endless belt charging member provided at a position opposite to the photoreceptor with the endless belt sandwiched therebetween. and presses the transferred object, which is electrostatically attracted to the endless belt and is conveyed, against the photoreceptor, and transfers the electrostatically charged toner carried on the surface of the photoreceptor to the transferred object. 1. An electrophotographic printing apparatus comprising: a wet wiping member for wiping a surface of the endless belt facing the charging member with water. 2. The electrophotographic printing apparatus according to claim 1, wherein the wet wiping member for wiping the surface of the endless belt with water is configured to be detachable from the surface of the endless belt.