JPH0125065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrophotography, and in particular, to a method in which the same elastic member performs the function of developing an electrostatic latent image formed on a photoreceptor and the function of cleaning developer remaining on the photoreceptor. Concerning electrophotography.

For example, in a two-cycle, one-copy electrophotographic apparatus, a developing device and a cleaning device have conventionally been provided separately. This made the device complicated and required a space to accommodate each device. However, in recent years, there has been a demand for smaller electrophotographic devices and simplification of the devices, and it has been desired to integrate each device.

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks of the prior art and to relate to an electrophotographic method that can have both a developing function and a cleaning function.

In electrophotography, an elastic porous member (hereinafter referred to as an elastic roller) capable of absorbing and squeezing out a developer is pressed against a photoreceptor, and the developer squeezed out when the roller is deformed is used to cover the surface of the photoreceptor. When cleaning the residual developer remaining on the photoreceptor after image development and transfer, preferably, a bias voltage having a component with a polarity opposite to that of the developer in the residual developer is applied to the elastic roller. (by applying a force to eliminate electrostatic adhesion between the residual developer and the photoconductor), the absorbing action at the time of restoring the deformation is improved, and the residual developer is absorbed and cleaned. .

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view of a two-cycle, one-copy electrophotographic apparatus according to an embodiment of the present invention.

The drawing shows an electrophotographic device using a moving document table type transfer method.
A document table 11 that moves back in the right direction is provided.
The document placed on the transparent portion of the document table 11 is slit-exposed from below by the illumination section 12 as the document table 11 moves leftward at a speed synchronized with the circumferential speed of the photosensitive drum 1. When the forward movement is completed, the document table 11 moves backward and returns to the illustrated position Co.

The photosensitive drum 1 has a photoconductive layer and an insulating transparent thin layer on an aluminum base.

Elements for each process are arranged around the photosensitive drum 1, and the photosensitive drum is first charged with a primary charge 2b, and then exposed to an image projected by an optical system from an illumination unit 12, and simultaneously charged with a secondary charge. An electrostatic latent image is formed by charging or AC neutralization by the device 2c. Next, the latent image is exposed entirely to light using a lamp 2d to increase the contrast, and then the liquid developing device 8
Then, post-charging is performed using the charger 16, and the image is transferred onto the transfer paper fed from the paper feed table toward the photosensitive drum 1 by the paper feed roller 13 by applying a bias at the transfer unit 4. After the transfer process, the transfer paper is transferred to a drying section 14 by a separating and conveying device 5.
The transferred image is dried and fixed on tray 1 outside the machine.
It is discharged at 5.

A developer solution in which developer particles are dispersed in a carrier solution is stored in a container below the photosensitive drum. The developing roller 3 is constructed by covering the surface of a conductive roller with a conductive sponge and further covering the outer surface of the sponge with an insulating rope. The developing roller 3 is in pressure contact with the photosensitive drum 1 at a pressure of approximately 8 kg/cm during operation, but during suspension of operation, the developing roller 3 is immersed in the developer in a container to prevent the developer impregnated into the elastic roller 3 from coagulating. do.

The document table 11 is in the Co position shown in the figure before starting the electrophotographic apparatus.
Located in At the same time as the start, the drum 1 rotates clockwise, and the process of forming a latent image begins from the surface of the drum located at the entrance of the primary bander 2b. When the above surface reaches the secondary charger 2c, the document table 11 is C ₁
The drum stops for a moment, and immediately starts forward movement E. At the same time, the drum is exposed to light, and the entire surface of the document is exposed by the full surface exposure device 2d, and reaches the pressure contact portion with the elastic roller 3. Until this time, the developer remaining on the surface of the drum preceding the above-mentioned surface is attracted to and cleaned by the developing roller by a bias voltage (described later) applied to the developing roller during contact with the developing roller. Therefore, from then on, the application of the cleaning bias is stopped based on the signal from the main body of the electrophotographic apparatus, and a signal for performing the developing function is given. Therefore, at this time, a bias of 150V is applied to the elastic roller 3 with respect to the bright area potential of the drum of 50V and the dark area potential of 750V to start development.

The developing action of the elastic roller 3 continues until the surface of the drum 1 returns to the contact area with the elastic roller 3. The drum 1 has already entered its second rotation, and after the above-mentioned contact, a cleaning signal is again given to the elastic roller.

The developing bias (150V) of the developing roller is canceled by the above cleaning signal, and the bias is changed to 1700V instead.
A bias of is applied. This bias has a component having a polarity opposite to that of the developer particles. Therefore, while the photosensitive drum is in contact with the developing roller, the residual developer can be absorbed by the roller together with the carrier liquid.

In this case, only about 0.7 μm of the carrier liquid film remains on the photosensitive drum after cleaning.
According to experiments, it has been found that if the thickness is 1 μm or more, uneven charging occurs during the next cycle.

According to this embodiment, the thickness of the developer film is extremely thin, 0.7μ, and the wet two-cycle one-copy electronics uses an elastic member that has both a cleaning function and a developing function, and has the ability to absorb and squeeze out the developer. I was able to obtain photographic equipment.

In the above embodiment, in the cleaning process,
A high voltage cleaning bias (1700V) was applied to the elastic roller to reduce the adhesion of residual developer to the photoreceptor. However, to deal with this, an AC corona discharge, for example, having a component with a polarity opposite to that of the charge of the residual developer particles is applied to the surface of the photosensitive drum before cleaning using a discharger 2c, and at the same time, the entire surface is exposed to light using an exposure device 2c.
You can use e. As a result, the potential on the surface of the photosensitive drum before cleaning can be lowered to 0 to 20 V, and the adhesion between residual developer particles and the surface of the photosensitive drum can be reduced. Therefore, the cleaning bias is
A low voltage of 900V is sufficient.

In addition, when forming a latent image on a photoreceptor with a two-layer structure of a photoconductive layer and a conductive layer by the Carlson process,
Instead of the above cleaning method, simply applying a corona discharge having a component of polarity opposite to the charge of the residual developer to the surface of the photoreceptor before cleaning can erase the above charge and the residual charge on the photoreceptor and improve the cleaning effect. be able to.

According to the present invention, it is possible to provide an electrophotographic method in which an elastic member capable of absorbing and squeezing out developer has both the function of cleaning residual developer on a photoreceptor and the function of developing a latent image.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an electrophotographic apparatus using the present invention. 1...Photosensitive drum, 2...Latent image forming section, 3...
Elastic roller, 4... Transfer section, 5... Separation roller, 6... Transfer material entry section, 7... Developer container, 8
...developing device, 9...stirring means, 10...machine box,
11... Original table, 12... Exposure section, 13... Paper feed roller, 14... Drying section, 15... Tray, 1
6...Liquid squeezing part.

Claims (1)

[Scope of Claims] 1. Development in which a latent image on a photoreceptor is developed by pressing an elastic member that can be impregnated with and squeezed out from a developer into pressure contact with a photoreceptor and squeezing out the developer impregnated into the elastic member. and a cleaning step of cleaning the developer remaining on the photoreceptor by restoring the deformation of the elastic member due to the pressure contact. 2. The electrophotographic method according to claim 1, wherein the cleaning step limits the carrier liquid film remaining on the photoreceptor to a thickness of less than 1 μm. 3. The electrophotographic method according to claim 1 or 2, wherein the cleaning step includes a step of relaxing the adhesion of developer particles in the developer remaining on the photoreceptor to the photoreceptor. Law. 4. The above-mentioned relaxation step applies a bias having a component having a polarity opposite to the polarity of the developer particles to the elastic member itself or to the photoreceptor in front of the area in which the elastic member presses against the photoreceptor. The electrophotographic method described in paragraph 3.