US3726782A - Cleaning device for wet-type electrophotographic device - Google Patents

Abstract

This invention provides a cleaning device for use in wet-type electrophotographic device to clean the sensitized surface of the photosensitive plate. The sensitized surface is cleaned by a cleaning solutions; the solution thus mixed with the toner is led to a tank, where the toner is separated and accumulated by the electrode plates by field effect; and the purified cleaning solution is pumped up for reuse.

Description

April 10, 1973 HIROSHI TANAKA ET AL CLEANING DEVICE FOR WET-TYPE ELECTROPHOTOGRAPHIC DEVICE Filed May 28, 1969 FIG. 3A

FIG. 3B

United States Patent 3,726,782 CLEANING DEVICE FOR WET-TYPE ELECTROPHOTOGRAPHIC DEVICE Hiroshi Tanaka and Yoshio Itoh, Tokyo, Japan, assignors to Canon Kabushiki Kaisha, Tokyo, Japan Filed May 28, 1969, Ser. No. 828,611 Claims priority, app gcation Japan, June 5, 1968,

rm. 01. B611; 5/00 US. Cl. 204-499 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electrophotographic equipment, and more particularly, to an improved cleaning device for wet-type electrophotographic device.

In conventional wet-type electrophotography, a uniform exposure is given to the photosensitive member having a photoconductive layer followed by the projection of an optical image that corresponds to the original image to form an electrostatic latent image thereof. The latent image thus formed is developed then to a visible image by a liquid developer comprising a highly insulating liquid having a pigment or a dye dispersed in it. At this time a cleaning solution is poured on the photosensitive member having the visible image to remove the fog. The photosensitive member is then dried and fixed.

In accordance with a conventional cleaning device, the surface of the picture after development is cleaned with a cleaning solution, and the cleaning solution that has mixed with the developer is led to the cleaning solution tank and drawn up from the tank by a pump to be used again.

Another conventional type of cleaning device, similar in construction to the above, has been offered to make it possible to clean the developer remaining on the Xeroxtype photosensitive plate and to reuse it after an electrostatic latent image is formed on it, developed, and then transferred to a transferable material.

However, the above-mentioned conventional devices have a defect not to attain its purpose of removing fog or clean the photosensitive plate, because a cleaning solution mixed with developer is used for cleaning after development or after the transfer of powder image.

This defect appears remarkable especially in performing color printing. In color printing, the original image must be color separated and the process of charging, exposure, development, and cleaning must be repeated for each color. Therefore, from economical reasons the same cleaning solution is often used in common to each color process. Consequently, the cleaning solution is contaminated very much by developers and it is not an easy task to obtain an expected result.

This invention solves the defect of the cleaning device of conventional type. This invention is characterized by the complete removal of fog from the picture surface after development in electrofax system, or from the photosensitive plate after the transfer in Xerox system in order to reuse it by cleaning the sensitized surface with a cleaning solution, by leading the cleaning solution mixed with developer to the cleaning tank, by separating and accumulating the toner by the electrode plates in the tank, by removing the toner, and by pumping up the refreshed cleaning solution for reuse.

Therefore, a main object of this invention is to offer a novel, improved cleaning device.

Another object of this invention is to offer a cleaning device which permits the cleaning solution to be used repeatedly.

A further object of this invention is to offer a cleaning device capable of completely removing the fog after development.

One of the still further objects of this invention is to offer a cleaning device suitable for use in color printing.

Other objects of this invention will be obvious to the person concerned from the contents of the specification or the claim hereinafter disclosed.

This invention will be explained more in detail referring to the accompanying drawings, in which:

FIG. 1 is a vertical cross section of an example of cleaning device which employs a cylindrical electrode tube;

FIGS. 2A and 2B show a vertical cross section and perspective views respectively, of another example of cleaning device which employs several perforated plate electrodes for purpose of meandering the cleaning solution; and

FIGS. 3A and 3B show a vertical and perspective views, respectively, of further example of cleaning device which employs several perforated plate electrodes for purpose of meandering the cleaning solution.

FIG. 1 that shows an example of the invention cleaning device provided with a purification equipment will be explained. In FIG. 1: 1 shows a purifying tank, 2 shows a pipe which leads the cleaning solution contaminated by the developer to the purifying tank 1 by a method not indicated in the drawing, 3 shows a hollow cylindrical electrode plate which is mounted in the purifying tank in such a way that its bottom opening edge is separated from the bottom of the purifying tank 1 by a small space 7 as shown in the drawing, 4 shows a power source, one terminal of which is connected to the said electrode plate 3 and the other is grounded. The polarity of the voltage applied to the electrode 3 from the power source 4 is desirable to be opposite to the polarity possessed by the toner contained in the developer. Tank 10 stores the cleaning solution that has already been purified, and is placed in the inside of the electrode 3, 5 shows a pump which draws up the purified cleaning solution through the gap between the electrode 3 and the cleaning solution purifying tank 10 upon operation of the motor M. The purified solution is discharged through a pipe 6. The photosensitive memher is cleaned with the punified cleaning solution discharged from the tube 6. In the case of color printing, this process is repeated for a number of times required for the number of color exposures, 9 shows a cock which functions to occasionally remove through it the toner that has accumulated on the bottom of the tank 1 as a result of purifying treatment.

The operation of the cleaning equipment shown in FIG. 1 will be explained. When the electrophotosensitive plate has been developed by electrophotography, or the image has been transferred, sensitized plate surface undergoes cleaning treatment. The cleaning solution used is now contaminated with toner. The contaminated cleaning solution is led to the tank 1 by way of the pipe 2 and is exposed to the electric field of the electrode plate 3 to which an appropriate voltage is applied from the power source 4. The toner mingled in the cleaning solution is accumulated on the electrode plate 3. The purified cleaning solution that has ascended passing through the space between the electrode plate 3 and the storage tank 10 is pumped up to the pipe 6 by the pump 5 which is operated by the motor M. The purified cleaning solution that has thus been drawn up serves cleaning treatment of electrophotosensitive plate after development.

FIG. 2 shows another example of the invented cleaning device, in which 11 shows a purifying tank, 12 shows a pipe leading the cleaning solution to the purifying tank, 14 shows a power source, 15 shows a pump, 16 shows a pipe that leads out the purified cleaning solution where M shows a pump, and 19 shows a cock. These are equivalent to those represented by symbols 1, 2, 4, 5, 6, 9, and M, in FIG. 1, respectively. And 13 through 13 show plate-type electrodes installed in parallel in the purifying tank 11. The number of the plates should be suitably determined. Holes 18 are bored in the electrode plate 13 through 13 alternately on each plate so that the cleaning solution meanders vertically when seen on the drawing. An arbitrarily selected polarity of voltage, desirably a voltage opposite in polarity to the toner, is applied to the electrode plates 13, through 13 like in FIG. 1 from power source 14. The pump is located at the position where the cleaning solution has meanderingly passed through the electrode plates 13 through 13 This pump functions to lead out the purified cleaning solution through the pipe 16 to be reused as the cleaning treatment solution.

FIG. 3 shows another example of the invented cleaning device. Here the electrode plates are so arranged as to meander the cleaning solution in all directions when seen on the drawing, namely, the electrode plates 23 through 23 are arranged alternatively backwards and forwards. Other things are similar in construction and operation to those shown in FIG. 1 and FIG. 2. The electrodes 3, 13 through 13 and 23 through 23,-, shown in FIG. 1 through FIG. 3 respectively can be given slight vibrations to increase their purifying function of cleaning solution.

As described above, the cleaning devices according to this invention have the above-mentioned construction, it is possible to clean the picture surface after developing the electric latent image, or to clean the sensitized surface after transfer in the case of Xerox-type electrophotography, and then to purify the contaminated cleaning solution containing the solvent of developer and toner by providing the electrodes either in cylindrical shape or plate shape or in other shapes which adsorb and separate the toner that causes the contamination by field effect, and supply thus purified cleaning solution drawn up through the pipe 6 to the picture surface again. The cleaning solution can be purified completely by such simple construction. Particularly, this invention is favorably applicable to color printing where the cleaning solution is more contaminated by the repeated cleaning treatment required by color exposures.

What is claimed is:

1. A cleaning device for electrophotographic apparatus comprising in combination: a cleaning station for removing, with a cleaning liquid, toner retained on the surface of an electrophotographic photosensitive member thereby producing contaminated cleaning liquid; tank means for storing cleaning liquid when not in use, said tank means having an inlet and an outlet; cleaning means disposed in said tank means for separating and collecting charged toner from said contaminated cleaning liquid to provide purified cleaning liquid, said cleaning means including an electrode structure; means coupled to said electrode structure having apertures therein and disposed between said inlet and said outlet such that cleaning liquid passes through said apertures in flowing from said inlet to said outlet for charging it to a given polarity opposite to the polarity of said charged toner; and circulating means conpled between said cleaning station and said tank means for transporting said contaminated cleaning liquid from said cleaning station to said tank means through said inlet and transporting said purified cleaning liquid through said inlet from said tank means to said cleaning station.

2. A cleaning device according to claim 1, wherein said electrode structure comprises a hollow cylindrical container and said apertures are located in the bottom thereof.

3. A cleaning device according to claim 1, wherein said electrode structure comprises a plurality of plate electrodes disposed transversely to said flow of cleaning liquid and said apertures are located therein out of registration relative to each other in the transverse direction.

4. A cleaning device according to claim 1, wherein said electrode structure comprises a plurality of plate electrodes disposed transversely to said flow of cleaning liquid and said apertures are located therein out of registration relative to each other in the longitudinal direction.

5. A cleaning device according to claim 1, wherein means are coupled to said cleaning means for imparting vibration thereto.

6. A cleaning device for electrophotographic apparatus comprising in combination: a cleaning station for removing, with a cleaning liquid, toner retained on the surface of an electrophotographic photosensitive member thereby producing contaminated cleaning liquid; tank means for storing cleaning liquid when not in use; cleaning means disposed in said tank means for separating and collecting charged toner from said contaminated cleaning liquid to provide purified cleaning liquid, said cleaning means including an electrode in the form of a hollow container having a plurality of apertures in the bottom thereof; means coupled to said electrode for charging it to a given polarity opposite to the polarity of said charged toner; a reservoir supported within said hollow container for receiving said purified cleaning liquid, said reservoir having an aperture in the top portion thereof; and circulating means coupled between said cleaning station and both said tankmeans and said reservoir for transporting said contaminated cleaning liquid from said cleaning station to said tank means outside said electrode and transporting said purified cleaning liquid from said reservoir to said cleaning station.

7. A cleaning device according to claim 6, wherein means are coupled to said cleaning means for imparting vibration thereto.

References Cited UNITED STATES PATENTS 767,964 8/ 1904 Schweitzer 204---149 820,482 5/1906 Dion 204-299 961,549 6/1910 Sperry 204-284 1,154,092 9/ 1915 Burdett 204-284 2,292,608 8/ 1942 Buckman et al. 204--299 2,440,050 4/ 1948 Fisher et a1 204-300 2,542,054 2/ 1951 Penney et al 204-299 2,682,505 6/1954 Greco 204-284 3,468,778 9/1969 Hirs et al 204-180 3,544,441 12/1970 Griswold 204--186 JOHN H. MACK, Primary Examiner A. C. PRESCOTT, Assistant Examiner US. Cl. X.R. 204-4

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