JPH09114340A - Wet type electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a safe and compact wet type electrophotographic device and to obtain a clear image without color mixture by separating liquid developer recovered from a cleaning part to toner grains and solvent by using a filter. SOLUTION: The rear stage of a filter tank 7 is provided with a solvent housing tank 10. Then, one part of the solvent recovered to the tank 10 is made to circulate to a cleaning means 5 and the other part is returned to a developer housing tank 4. In such a case, the solvent separated by the filter 8 is temporarily stocked in the tank 10 and delivered to the cleaning means 5. Then, the dirty blade, the dirty sponge roller and the like of the cleaning means 5 are washed. Since a defective cleaning action is not executed by washing the blade, the sponge roller and the like, the excellent image without abnormality such as a black line is obtained. Besides, when the quantity of the solvent in the tank 10 is equal to or over the prescribed quantity, the solvent is returned to the tank 4 and reutilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet electrophotographic apparatus in which an electrostatic latent image formed on an image bearing member such as a photoconductor is developed with a liquid developer. When the toner is transferred to paper or the like, some of the liquid developer remaining on the image carrier is removed to clean the image carrier, and at least the carrier liquid of the recovered liquid developer is imaged. The present invention relates to a wet electrophotographic apparatus that can be reused as a cleaning liquid for a carrier.

[0002]

2. Description of the Related Art When a copy is obtained by an electrophotographic method, it is roughly classified into a dry method or a wet method. In particular, when a faithful copy is desired for an original, a wet electrophotographic method is generally used which uses a liquid developer in which fine toner particles are dispersed in a carrier liquid.

By the way, in the wet electrophotographic method or apparatus, after the toner is transferred onto the recording paper, the liquid developer remaining on the surface of the image bearing member is removed and collected, and at the same time, with a solvent (generally a carrier liquid is used). A method of cleaning the surface of the image bearing member and returning them to the developing tank is generally used. However, according to this method, there is almost no problem in obtaining a single-color copy, but as with a full-color copying machine, there are three or four colors of cyan, magenta, yellow, and (black). When a liquid developer is used, there is a problem that the colors are inevitably mixed and the original color tone changes.

In order to solve such a problem, a voltage having a polarity opposite to that of the liquid toner is applied to the cleaning means (JP-A-5-46053), or a toner concentration detecting means is provided in the cleaning liquid tank. When the toner concentration in the tank exceeds a predetermined value by the toner concentration detecting means, the toner in the cleaning liquid is electrodeposited on the electrode roller to perform the toner collecting operation (Patent Publication 6-
No. 90587) has been proposed.

[0005]

However, it is necessary to apply a voltage of about 800 V when applying it to the above-mentioned conventional cleaning means or when electrodepositing the toner to the electrode roller, so that safety and running are ensured. There arises a problem that cost and size of the device cannot be avoided. Therefore,
A first object of the present invention is to provide a safe and compact wet electrophotographic apparatus capable of preventing color mixture even when a color liquid developer is used and obtaining a clear image without changing color characteristics. It is provided. A second object of the present invention is to provide a liquid developing color electrophotographic apparatus which can be recycled without discarding the developing solution after cleaning. A third object of the present invention is to provide a liquid-developing color electrophotographic apparatus that does not cause cleaning failure and does not generate abnormal images.

[0006]

The present invention relates to a wet electrophotographic apparatus for developing an electrostatic charge image with a liquid developer in which toner particles containing an adhesive and a binder resin as main components are dispersed in a carrier liquid. Cleaning means for removing excess untransferred liquid developer from the surface of the image carrier after development and transfer to plain paper, etc., and separating means for separating the liquid developer recovered by the cleaning means into toner particles and carrier liquid And a pipe for sending the carrier liquid derived from the separating means to a developer storage tank or a solvent storage tank.

In the wet electrophotographic apparatus of the present invention,
(1) A forcible suction mechanism (generally a suction pump is provided) provided in the middle of a pipe for sending the carrier liquid derived from the separating means to a developer storage tank or a solvent tank, and / or (2) It also includes one provided with a circulation path for guiding a part of the carrier liquid derived from the separating means directly or from the solvent storage tank to the cleaning means.

In the wet electrophotographic apparatus of the present invention, the carrier liquid, which is one of the constituents of the developer, is circulated and used as the cleaning liquid as shown in FIG. For this reason, it is advantageous to select a solvent which is also useful for cleaning the image carrier after the transfer step. Therefore, as the carrier liquid (solvent) of the liquid developer used here, those containing silicone oil or fatty acid ester as a main component are particularly preferable. Further, the liquid developer (cleaning liquid = containing solvent) collected by the cleaning means is used as toner particles and carrier liquid (including cleaning liquid).
It is advantageous to use a tank accommodating a filter having a pore size of 0.01 to 10 μm, preferably 0.4 to 0.8 μm as a means for separating into, and paper, nylon or polyester is preferably used as the material of the filter. .

[0009]

1, 2 and 3 are schematic views showing three examples of the wet electrophotographic apparatus of the present invention. In addition,
These are for each color. Therefore, in a full-color wet type electrophotographic apparatus, the systems shown in FIG. 1, FIG. 2 or FIG. 3 are provided in cyan, magenta, yellow and (black) 3 to 4, respectively. First, the apparatus shown in FIG. 1 will be described. The developing solution supplied by the developing means 2 to visualize the latent image on the photoconductor 6 is transferred to plain paper or the like (transfer paper) not shown in the transfer means 3. Transcribed. The untransferred liquid developer remaining on the photoconductor 6 without being transferred to the transfer paper is removed from the photoconductor 6 by the cleaning unit 5.
The removed liquid developer is separated into toner particles and a solvent (carrier liquid) by a filter 8 by a separating means (filter tank) 7. The toner particles remain on the filter 8 and the solvent is returned to the developer storage tank 4 for reuse.

The apparatus shown in FIG. 2 is the same as the apparatus shown in FIG. 1 except that a suction pump 9 is attached to the latter stage of the filter tank 7. The untransferred liquid developer, the cleaning liquid, or a mixture thereof in the filter tank 7 is sucked by the suction pump 9, so that the developer in the filter tank 7 is instantly separated into toner particles and a solvent by the filter 8. You can

The apparatus of FIG. 3 is provided with a solvent storage tank 10 after the filter tank 7 in the apparatus of FIG. 1, and a part of the recovered solvent is circulated to the cleaning means 5,
This is a device in which the other part is returned to the developer storage tank. The solvent separated by the filter 8 is the solvent storage tank 1
It is temporarily stocked at 0 and sent to the cleaning means 5. By sending the solvent to the cleaning means 5,
The dirty blade, sponge roller, etc. of the cleaning means 5 are washed. By cleaning these blades, sponge rollers, and the like, cleaning failure does not occur, so that a good image without abnormal images such as black stripes can be obtained. When the amount of the solvent in the solvent storage tank 10 exceeds a certain amount, it is returned to the developer storage tank 4 and reused.

[0012]

Next, the present invention will be described more specifically with reference to examples.

Example 1 An experiment was conducted by using the apparatus shown in FIG. 1 which was made by modifying a wet copying machine (CT-5085) manufactured by Ricoh Co., Ltd., and using a membrane filter (pore size 1 μm) manufactured by Toyo Roshi Kaisha, Ltd. as a filter. went. When a chart (A-4 size) with an image area of 6% was used and 500 sheets were continuously run, the liquid developer (Recopy PPC toner type 5080 black manufactured by Ricoh Co., Ltd.) was completely removed by the filter 8 with the toner particles and the solvent. And a colorless and transparent solvent is separated into
Returned to.

Example 2 An experiment was conducted by using the apparatus shown in FIG. 2 and using a membrane filter (pore size 0.45 μm) manufactured by Toyo Roshi Kaisha, Ltd. as a filter. Using a chart (A-4 size) with an image area of 30%, 3000 sheets were continuously run. As a result, the liquid developer (Recopy PPC toner type 5080 green manufactured by Ricoh Co., Ltd.) was completely removed by the filter 8 with the toner particles and the solvent. And a colorless and transparent solvent is separated into
Returned to.

Example 3 An experiment was conducted using the apparatus of FIG. 3 and using a Millipore filter (pore size 0.8 μm) as the filter. When a chart (A-4 size) with an image area of 10% was used and 5000 sheets were continuously run, the liquid developer (Recopy PPC toner type 5080 blue manufactured by Ricoh Co., Ltd.) was completely removed by the filter 8 with the toner particles and the solvent. Then, only the colorless and transparent solvent was returned to the developer storage tank 4. No abnormal image was generated during the run, and when the cleaning means (blade, sponge roller) was examined after the run, there was almost no stain.

[0016]

According to the invention of claim 1, since the liquid developer recovered from the cleaning section is separated into toner particles and solvent by the filter, a safe and compact wet electrophotographic apparatus can be provided. Further, a clear image without color mixture can be obtained. According to the invention of claim 2,
Suction pump 7 (forced suction mechanism) in the latter stage of the cleaning section
Since it has, the developer can easily pass through the filter, and the separation ability of the toner particles and the solvent is enhanced. Thereby, the recycling efficiency of the solvent can be improved.
According to the invention of claim 3, part of the separated solvent is circulated between the cleaning portion and the filter, so that the cleaning portion can be washed. This allows
Since cleaning failure does not occur, a good image without an abnormal image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a wet electrophotographic apparatus of the present invention.

FIG. 2 is a diagram schematically showing another example of the wet electrophotographic apparatus of the present invention.

FIG. 3 is a diagram schematically showing still another example of the wet electrophotographic apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 charging means 2 developing means 3 transfer means 4 developing solution storage tank 5 cleaning means 6 image carrier (photoreceptor) 7 filter tank (separating means) 8 filter 9 suction pump 10 solvent storage tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyo Mizuno 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Aki Koseki 1-3-3 Nakamagome, Ota-ku, Tokyo No. Stock Company Ricoh

Claims (6)

[Claims] 1. In a wet electrophotographic apparatus for developing an electrostatic charge image with a liquid developer in which toner particles containing an adhesive and a binder resin as main components are dispersed in a carrier liquid, development, transfer to plain paper, etc. After that, it is derived from a cleaning unit that removes the excess untransferred liquid developer from the surface of the image carrier, a separation unit that separates the liquid developer recovered by the cleaning unit into toner particles and carrier liquid, and the separation unit. A wet electrophotographic apparatus comprising a pipe for sending a carrier liquid to a developer storage tank or a solvent storage tank. 2. The wet electrophotographic apparatus according to claim 1, wherein a forced suction mechanism is provided in the middle of a pipe for sending the carrier liquid drawn out from the separating means to a developer storage tank or a solvent storage tank. . 3. A circulation path for guiding a part of the carrier liquid drawn out from the separating means directly or from a solvent storage tank to the cleaning means.
The wet electrophotographic apparatus described. 4. The wet electrophotographic apparatus according to claim 1, 2 or 3, wherein the carrier liquid for the liquid developer contains silicone oil or a fatty acid ester as a main component. 5. The separation means has a pore size of 0.01 to 10 μm.
4. The wet electrophotographic apparatus according to claim 1, which is composed of a tank accommodating a m filter. 6. The wet electrophotographic apparatus according to claim 5, wherein the material of the filter is paper, nylon or polyester.