JPS61198254A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To reduce a decrease in the electrostatic charge potential of a photosensitive body due to electrostatic discharging, to use the charging ability of the photosensitive body at a maximum, and to perform excellent image formation by composing an electrostation discharging means of a contact type discharging part which brings a conductive member into contact with the surface of the photosensitive body. CONSTITUTION:A developer remaining on the photosensitive drum 1 after a developer image is transferred onto a transfer material P is cleaned up by a cleaning device 7 and the photoconductive drum contacts a conductive rubber roller 10 as a contact type discharging means 8 to erase an after image on the drum 1, so thereby holding itself in readiness of next copying operation. When the drum is discharged by this discharging means 8, no light irradiation is performed, so the generation of an optical generating carrier which may cause a decrease in charge potential is reduced.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention provides an improvement in an electrophotographic apparatus such as a transfer type electrophotographic copying machine that can prevent a reduction in the charged potential of a photoreceptor due to static elimination. Regarding.

[Technical background of the invention and its problems] In electrophotographic devices such as electronic copying machines and laser printers, the role of the photoreceptor is to retain the charge generated by corona discharge for a certain period of time, and to absorb the charge generated in the photoreceptor due to image exposure. One of the pairs of electrons and holes neutralizes the surface charge. At this time, an electrostatic latent image is formed on the surface of the photoreceptor,
Visualization is achieved by attaching toner charged with the opposite sign to the charge on the surface of the photoreceptor using Coulomb force. This toner is then transferred to paper, creating an image on the paper. Further, the photoreceptor requires erasure of the electrostatic latent image for the next image formation, and this is usually accomplished by irradiating the entire surface of the photoreceptor with light.

This process is called static elimination.

Photoreceptors conventionally used include chalcogenides such as Se and organic semiconductors such as PVK (polyvinyl carbazole), but these have low sensitivity to light in the visible range. Furthermore, it has low hardness and has a short life when applied to electrophotographic photoreceptors. Additionally, there are some additional issues, such as temperature stability.

Based on these points, amorphous silicon is a material that has recently attracted attention. Amorphous silicon has a wide range of photosensitive wavelengths, good sensitivity, is hard with a Vickers hardness of about 1000, is expected to have a long life, and has many advantages such as excellent temperature stability. Due to these advantages, when amorphous silicon is used for electrophotography, the time required for one process can be shortened. That is, amorphous silicon is effective in copying machines that perform high-speed copying. However, in this case, in a normal copying process, the charge potential decreases significantly due to static elimination. This is because the electron-hole pairs generated in excess due to light irradiation for static elimination enter the next charging process before they are completely recombined. This is a phenomenon often seen in highly sensitive photoreceptors, but since amorphous silicon has high sensitivity and a wide sensitive wavelength range, photogenerated carriers are likely to be generated throughout the photoreceptor.

That is, long wavelength light with a relatively small extinction coefficient reaches the interior of the photoreceptor and is absorbed throughout the entire area. When this occurs over a wide range, the carrier density is low, so the probability of recombination is low, and as a result, the next time the charge is 50% lower than when left in the dark, even with the same applied voltage as the previous time. A problem arises in that it is only charged to a potential of about 80%.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide an electrophotographic apparatus that can prevent a decrease in the charged potential of a photoreceptor due to static elimination and can form good images. It is something.

[Summary of the Invention] In order to achieve the above object of the present invention, the static eliminating means is constituted by a contact type static eliminating unit that brings a conductive member into contact with the surface of the photoreceptor, thereby preventing a decrease in the charged potential of the photoreceptor due to static elimination. It has been made possible to do so.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is an explanatory diagram showing a schematic structure of an electrophotographic copying apparatus suitable for the present invention. In the figure, 1 is a photosensitive drum having an amorphous silicon photosensitive member 2 arranged on its surface. The photosensitive drum 1 is rotated in the direction of the arrow by a driving means (not shown), and around the drum 1, a charging device @3 as a charging means, an exposure device 4 as a latent image forming means, and a developing means are sequentially arranged along the direction of rotation. A developing device 5 as a developing device 5, a transfer device @6 as a transfer device, a cleaning device 7 as a cleaning device, and a static eliminating device 8 consisting of a contact type static eliminating unit that contacts the conductive rubber roller 10 are provided.

After the surface of the photosensitive drum 1 is uniformly charged by the charging device 3, the surface of the photosensitive drum 1 is exposed to an image of a document (not shown) by facing the exposure device 4, thereby forming an electrostatic latent image. Next, this electrostatic latent image is developed by facing the developing device 5, and this developer image is sent to the transfer device 6 side.

Meanwhile, in synchronization with the developer image forming operation, a transfer material P is fed into the image transfer section 9 between the transfer device 6 and the photoreceptor drum 1, and the developer image formed on the photoreceptor drum 1 is transferred. Device 6
The image is transferred to the transfer material P by the action of . The transfer material P to which this developer image has been transferred is peeled off by a peeling device (not shown), and then led to a fixing device, where the transferred image is melted.

On the other hand, after the developer image is transferred onto the transfer material P, the residual developer remaining on the photoreceptor drum 1 is cleaned by a cleaning device 7, and a conductive rubber roller 1, which is a contact type static eliminating means 8, is cleaned by a cleaning device 7.
0, the afterimage on the photosensitive drum 1 is erased, and the photosensitive drum 1 is prepared for the next copying operation.

When static electricity is removed by such static elimination means 8, since no light is irradiated, band I! There is no generation of photogenerated carriers that lead to potential reduction.

In the above-mentioned embodiment, the contact type static eliminator 8 was constructed from the conductive rubber roller 10, but the present invention is not limited to this, and as shown in FIG. As shown in the figure, conductive brush 12
Furthermore, as shown in FIG.
and the conductive rubber roller 10 may be used.

Furthermore, it may be made of other conductive materials such as rods.

Further, the blade 11 may be made of metal or conductive rubber, but care must be taken not to damage the photoreceptor 2. In other words, be careful about the angle and shape of the hit.

Roller 10. Even if the rod is made of metal, it is desirable that it be rotatable around an axis parallel to the rotation axis of the photoreceptor 2.

The brush is thin, made of soft metal, and preferably dense.

Furthermore, some of these items may be combined, and combinations of brushes and other items were particularly effective.

In addition, a roller 10 and a blade 1 constituting a contact-type static eliminator are also included.
1. The members having four electric properties, such as the brush 12 and the rod, are not limited to those made of conductive materials, and may be made of conductive treatment.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the invention.

[Effects of the Invention] As explained above, according to the present invention, it is possible to reduce the decrease in the charging potential of the photoreceptor due to static elimination, to make maximum use of the charging ability of the photoreceptor, and to perform good image formation. This has the advantage of being able to provide an electrophotographic device.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing one embodiment of an electrophotographic copying apparatus suitable for the present invention, and FIGS. 2 to 4 are explanatory views showing other different embodiments of the present invention. 1... Photoreceptor drum, 2... Photoreceptor, 3... Charging device (charging means), 4... Exposure device (latent image forming means)
, 5...Developing device (developing means), 6... Transfer device (
transfer means), 7... cleaning device (cleaning means), 8... static eliminating means, 9... image transfer section, 10.
... Conductive rubber roller, 11 ... Conductive blade, 1
2... Conductive brush, P... Transfer material. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (2)

[Claims] (1) A latent image forming means for forming a latent image on the surface of a photoreceptor formed of amorphous silicon, a developing means for developing the latent image formed by the latent image forming means, and a latent image formed by the developing means. a transfer means for transferring the image onto a transfer material, a cleaning means for removing developer remaining on the surface of the photoreceptor after the image is transferred by the transfer means, and a cleaning means for removing the photoreceptor whose surface has been cleaned by the cleaning means. 1. An electrophotographic apparatus comprising a static eliminator for removing static electricity, characterized in that the static eliminator comprises a contact type static eliminator that brings a conductive member into contact with the surface of a photoreceptor. (2) The electrophotographic apparatus according to claim 1, wherein the contact-type static eliminator is made of one or more conductive members selected from rollers, blades, brushes, and rods.