JPS61198255A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent the electrostatic charge potential of a photosensitive body from decreasing owing to electrostatic discharging and to form an excellent image by composing an electrostatic discharging means of the 1st contact type discharging part and the 2nd light irradiation type discharging part. CONSTITUTION:The discharging means 8 consists of the 1st contact type discharging part 10 and the 2nd irradiation type discharging part 11 provided at its downstream side; and the 1st discharging part 10 is composed of a conductive roller 12 and thd 2nd discharging part 11 provided at the downstream side is composed of a discharging lamp 13. The roller 12 and a rod are made of metal and preferably rotatable around axes parallel to the rotating shaft of the photosensitive body 2. A brush is made of thin and soft metal and preferably close.

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 hold the charge generated by the corona fist for a certain period of time, and to remove 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, and visualization is achieved by attaching toner charged with the opposite sign to the charge on the photoreceptor surface using Coulomb force. This toner is then transferred to a transfer material such as paper to obtain an image on the transfer material.

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.

Conventionally, photoreceptors 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 by light irradiation for snow removal enter the next charging process before they are completely recombined. This phenomenon is often observed in highly sensitive photoreceptors, but amorphous silicon is highly sensitive and has a wide sensitive wavelength range, so photogenerated carriers are easily 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%.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its object is to provide an electrophotographic apparatus that can prevent the charge potential of a photoreceptor from decreasing due to snow removal and can perform good image formation. This is what we are trying to provide.

[Summary of the Invention] In order to achieve the above object, the present invention includes a first charge removing section of a contact type that brings a conductive member into contact with the surface of the photoreceptor, and a light beam of a predetermined amount of light or more. By bringing a conductive substance into contact with the photoreceptor, most of the potential is erased, and the final amount of light is 1/1 of the amount of light normally required for static elimination. By irradiating light of 2 or less, it is possible to prevent a decrease in the charged potential of the photoreceptor due to snow removal.

[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 photoreceptor drum 1 is rotated in the direction of the arrow by a driving means (not shown), and around the photoreceptor drum 1 are sequentially arranged along the direction of rotation a charging device 3 as a charging means, an exposure device 4 as a latent image forming means, and a developing means as a developing means. Developing device F! 5, a transfer device 6 as a transfer means, a cleaning device 7 as a cleaning means, and a static elimination means 8 are provided.

After the surface of the photosensitive drum 1 is uniformly charged by the charging device 3, the photosensitive drum 1 is exposed to an image of a document (not shown) by facing the exposure bag @4, and an electrostatic latent image is formed. 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 and fixed.

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 the cleaning device 7, and the residual image on the photoreceptor drum 1 is roughly erased by the static eliminating means 8. and prepares for the next copying operation.

The static eliminator 8 includes a contact type Ml static eliminator 10 and a light irradiation type second static eliminator 11 provided on the downstream side thereof, and the first static eliminator 10 is connected to a conductive rubber roller 12, and
The second static eliminator 11 provided on the downstream side is composed of a static eliminator lamp 13.

Thus, the surface of the photoreceptor drum 1 is 500 mm wide by facing the conductive rubber roller 12 as the first static eliminator 10.
The surface potential of 0■ fell to about 100V.

Next, after this, when light with an amount of light of 0.21 UX -3 ec was irradiated, the residual potential decreased to 5 V or less, and static elimination was completed.

In this method, the light m used for static elimination is a normal 11u×Se
Since the amount of 0.21 ux · Sec is small compared to c, the decrease in the charged potential due to snow removal was about 10% of the charged potential after being left in the dark.

In the above-mentioned embodiment, the contact-type first static eliminator 10 of the static eliminator 8 was constructed from the conductive rubber roller 12, but the present invention is not limited to this, and as shown in FIG. From the blade 14 made of material, from the conductive brush 15 as shown in FIG. 3, and further from the conductive brush 15 and the conductive rubber row 5 as shown in FIG.
It may be a combination with 12. Furthermore, it may be constructed of other conductive materials such as rods.

Further, the blade 14 may be made of metal or conductive rubber, but care must be taken not to scratch the photoreceptor 2. In other words, be careful about the angle and shape of the hit.

Even if the roller 12 and the rod are made of metal, it is desirable that they 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, it is also possible to combine some of these items (particularly the combination of brushes and other items was effective).

Further, the conductive members such as the roller 12, blade 14, brush 15, rod, etc. that constitute the first static eliminator 10 are not limited to those made of conductive materials, but may be those that have been subjected to conductive treatment. Good too.

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 charged potential of the photoconductor due to static elimination, to make maximum use of the charging device of the photoconductor, 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. DESCRIPTION OF SYMBOLS 1... Photoreceptor drum, 2... Photoreceptor, 3... Charging device (charging means), 4... Exposure device t! (Latent image forming means), 5...Developing device W1 (developing means), 6... Transfer device (@photographing means), 7... Cleaning device (cleaning means), 8... Static elimination means, 9 ...image transfer section,
DESCRIPTION OF SYMBOLS 10... Contact type first static eliminator, 11... Light irradiation type second static eliminator, 12... Conductive rubber roller, 13.
... Static elimination lamp, 14... Conductive blade, 15...
- Conductive brush, P... transfer material. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Prisoner Figure 4

Claims (3)

[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. An electrophotographic apparatus comprising a static eliminator for removing static electricity, wherein the static eliminator includes a contact-type first static eliminator that brings a conductive member into contact with the surface of the photoreceptor, and irradiates light with an amount of light equal to or less than a predetermined amount. 1. An electrophotographic apparatus comprising: a light irradiation type second static eliminator. (2) The electrophotographic apparatus according to claim 1, wherein the first static eliminator is made of one or more conductive members selected from rollers, blades, brushes, and rods. . (3) The second static eliminator is 1/2 the amount of light normally required for static neutralization.
An electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus emits the following light.