JPH03293384A - Pre-wet device for wet electrophotographic copying device - Google Patents

Abstract

PURPOSE:To supply the sufficient quantity of developer to the surface of a photosensitive body by injecting developer solvent into a hollow cylinder so that it may be expanded in a radial direction and bringing a wetting roller which is constituted so that the injected solvent can permeate into contact with a photosensitive body in a state it is expanded. CONSTITUTION:The wetting roller 2 provided at a position opposed to a rotating drum 1 is formed to have cylindrical hollow structure and expanded when the developer solvent is injected into a storage chamber 2a from an injection port 3, and formed of a material through which the developer solvent can permeate from the inside to the outside, for instance, air-permeable sponge. When pressure becomes high by being filled the developer solvent which is injected into the storage chamber 2a from the injection port 3 through a supply tube 4, the roller 2 is expanded to the outside in the radial direction and contacts with the photosensitive body A on the rotating drum 1. The wetting roller 2 rotates in such a state, the surface of the photosensitive body A is wetted by the developer solvent which permeates from the outside surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pre-wet device used in a wet electrophotographic device.

[Prior Art] Conventionally, in a wet electrophotographic apparatus, in order to prevent so-called background smearing in which unnecessary toner adheres to non-image areas, a wetting roller made of rubber, sponge, etc. that permeates the developer solvent, and a solenoid are used. and a pre-wet device consisting of a wetting roller moving means and the like. The conventional wetting roller is rotated with the lower part immersed in the developer solvent and the upper part of the wetting roller in contact with the surface of the photoreceptor, and the developer solvent sucked into the developer solvent is transferred to the photoreceptor. By contacting the surface, the surface of the photoreceptor is wetted.

[Problems to be Solved by the Invention] However, in the conventional pre-wet device described above, there is a limit to the amount of developer solvent that the wetting roller can suck in, and the wetting roller sucks in the developer solvent while rotating, which makes it difficult to expose to light. A sufficient amount of developer solvent cannot be supplied to the body surface. For this reason, there was a drawback that a good image could not be obtained due to insufficient moisture. Furthermore, since this type of wetting roller wets only the surface of the photoreceptor, a moving mechanism for moving the wetting roller toward and away from the photoreceptor drum is required, resulting in a complicated structure.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pre-wet device that has a simple structure and reliably wets a photoreceptor before a developing process.

[Means for Solving the Problems] In order to achieve this object, the pre-wet device of the present invention has a wetting roller that is a hollow cylindrical body into which a developer solvent can be press-fitted, and a developer solvent can be press-fitted into the wetting roller. When press-fitted, the wetting roller is configured to expand in the radial direction and allow the developer solvent to permeate therein, and the wetting roller is arranged so that its outer peripheral surface comes into contact with the photoreceptor only in the expanded state.

[Function] According to the pre-wet device of the present invention having the above configuration, the wetting roller is normally located at a non-contact position away from the photoreceptor. When wetting the photoreceptor, when the developer solvent is press-fitted into the wetting roller, the peripheral surface of the wetting roller expands radially outward and becomes in contact with or capable of contacting the photoreceptor. Further, the developer solvent press-fitted into the wetting roller seeps out from inside to the outer circumferential surface. Therefore, when the photoreceptor is sent to the wetting roller and comes into contact with the wetting roller, the wetting roller wets the surface of the photoreceptor while rotating in the direction in which the photoreceptor is fed.

On the other hand, if the pressing of the developer solvent into the wetting roller is stopped, the peripheral portion of the roller contracts radially inward and separates from the surface of the photoreceptor.

[Example 1] Hereinafter, an example embodying the present invention will be described with reference to the drawings. FIG. 1 shows a front perspective sectional view of the pre-wet device during wet work, and FIG. 2 shows a side sectional view of the same.

A wetting roller 2, which is a feature of the present invention, is provided at a position facing a rotating drum 1, which serves as a holder for the photoreceptor A.

The wetting roller 2 has a cylindrical hollow structure with a developer solvent storage chamber 2a at its center. The wetting roller 2 is made of a material, such as a breathable sponge, that expands when the developer solvent is pressurized into the storage chamber 2a and allows the developer solvent to seep out from the inside to the outside. are held by circular plates 2c and 2d.

Further, in FIG. 1, a developer solvent injection port 3 is formed in the center of the left circular plate 2C.

A developer solvent supply pipe 4, which also serves as a support shaft, is integrally connected to the press port 3 of the circular plate 2c, and a support shaft 5 is fixed to the center of the right circular plate 2d. . and,
The supply pipe 4 and the support shaft 5 are connected to a pair of roller supports 10 with bearings 4
a and 5a, respectively, so that the wetting roller 2 is rotatably supported between both roller supports 10.

One end of the supply pipe 4 is connected to a supply hose 11 through a rotary joint (not shown) as shown in FIG. The developer solvent in the tank 13 can be pumped into the storage chamber 2a in the wetting roller 2. The developer solvent tank 13 has an open top end, and the wetting roller 2 is installed in the developer solvent tank 13 with a portion of the wetting roller 2 protruding from the top opening 13a. The position of the wetting roller 2 relative to the rotary drum 1 is such that it does not come into contact with the photoreceptor A held on the rotary drum 1 during non-operation (other than during wetting work), as shown in FIG. During operation (during wet work), it is set so as to come into contact with the photoreceptor A as shown in FIG. In other words, when the developer solvent is press-fitted into the wetting roller 2 (see FIG. 2), it comes into contact with the photoreceptor A on the rotating drum 1, but when the developer solvent is not press-fitted (see FIG. (see figure), it is set at a position where it does not come into contact with the photoreceptor A.

In addition, in FIG. 4, on the right side of the wetting roller 2 (in the moving direction of the photoreceptor A, there is a developing device 14 for supplying a developer to the electrostatic latent image on the photoreceptor A and developing it, and a developing device 14 for removing excess developer). A squeeze roller 15 is provided.

Next, the operation of the pre-wet device of the above embodiment will be explained. During operation, the developer solvent pumped by the supply pump 12 (FIG. 4) is as shown in FIG.
It is fed through the supply pipe 4 from the press inlet 3 in the direction of the arrow a, and is press-fitted into the storage chamber 2a of the wetting roller 2. The press-fitted developer solvent is filled into the storage chamber 2a, and when the storage chamber 2a is full, the pressure inside the storage chamber 2a increases and the wetting roller 2 swells radially outward (in the direction of the arrow). As a result, the outer circumferential surface of the wetting roller 2 comes into contact with the photoreceptor A on the rotating drum 1, as shown in FIG. Further, as the internal pressure increases, the developer solvent in the storage chamber 2a leaks out in the direction of the arrow through the wetting roller 2, and wets the outer circumferential surface of the wetting roller 2. Then, as the rotary drum 1 rotates in the direction of the arrow d as shown in the figure, the wetting roller 2 comes into contact with the photoreceptor A that is being sent while being held on the rotary drum 1, and the wetting roller 2 rotates in the direction of the arrow e. . In this state,
The developer solvent supplied to the outer peripheral surface of the wetting roller 2 wets the surface of the photoreceptor A at the contact point f.

The photoreceptor A, whose surface has been wetted in this way, is transferred to the developing device 1.
At step 4, a developer is supplied and developed. Furthermore, the excess developer is squeezed out and removed by the squeezing roller 15, and the development work is completed. On the other hand, when the wetting roller 2 is not in operation, the pressure injection of the developer solvent into the storage chamber 2a of the wetting roller 2 is stopped, so the pressure inside the storage chamber 2a decreases, and the wetting roller 2 contracts radially inward due to its self-restoring force. Therefore, the wetting roller 2 is in a non-contact state with the photoreceptor A as shown in FIG. Also,
There is no leakage of the developer solvent to the outer peripheral surface of the wetting roller 2.

Therefore, the wetting roller 2 is connected to the rotating drum 1 by a special mechanism.
It becomes possible to selectively wet only the portion of the photoreceptor wound around the rotary drum 1 with the wetting roller 2 without separating it from the rotary drum 1.

[Effects of the Invention] As is clear from the above detailed description, the pre-wet device of the present invention has the following effects.

By press-fitting the developer solvent into the wet roller and allowing it to seep out to the outer circumferential surface and come into contact with the photoreceptor, a sufficient amount of developer solvent can be supplied to the photoreceptor surface, so there is no background smearing and the result is always good. You can get a good image.

Further, there is no need for a mechanism for separating the wetting roller from the photoconductor or bringing it close to them, and the structure is simple, resulting in cost reduction and space saving.

[Brief explanation of the drawing]

1 to 4 show embodiments embodying the present invention; FIG. 1 is a diagram showing a pre-wet device portion of a wet type electrophotographic apparatus, FIG. 2 is a side view of the same, and FIG. FIG. 4, which is an explanatory diagram of its operation, is a diagram showing the overall structure of the wet type electrophotographic apparatus. In the figure, 1 is a drum, 2 is a wetting roller, and A is photosensitive paper.

Claims (1)

[Claims] 1. After forming an electrostatic latent image by charging and exposing the photoreceptor on the drum, the photoreceptor is subjected to a developing process in a wet electrophotographic apparatus in which a developer is supplied to the electrostatic latent image to obtain a visible image. Previously, the wetting roller for wetting with the developer solvent was a hollow cylindrical body into which the developer solvent could be press-fitted, and when the developer solvent was press-fitted into the inside, it expanded in the radial direction and the developer solvent 1. A pre-wet device, characterized in that the wetting roller is configured to be penetrable and is arranged so that the outer peripheral portion of the wetting roller comes into contact with the photoreceptor only when the wetting roller is expanded.