JPH02157849A - Selenium photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To prevent falling of thunderbolt and to reduce defects of picture image due to the thunderbolt by regulating a charge potential per 1mum film thickness of a photosensitive layer in an electrophotographic sensitive body consisting of an Se photoconductive material, to 5-9V. CONSTITUTION:Relations between the number of defect of picture images generated due to thunderbolt and charge potentials per 1mum film thickness of a photosensitive layer formed by vacuum deposition of an Se photoconductive material on an electroconductive base body have been researched by changing the amt. of vacuum deposition and performing a picture forming test. As a result, it has been found that such defects are reduced efficiently when the charge potential is <=9V per 1MUm. However, it is not practical to reduce the charge potential per 1mum to <=5V, because the film thickness will be >=120mum for 600-100V charge potential, which is used conventionally, requiring too much amt. of deposited material and too much time for vacuum deposition. Accordingly, it is concluded that defects of picture image due to falling of thunderbolt is most efficiently prevented when a charge potential per 1mum thickness of a photosensitive layer is 5-9V per 1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic selenium oxide film comprising a photosensitive layer made of a selenium-based photoconductive material on a conductive substrate 1, for example, a substrate mainly composed of aluminum. Regarding photoreceptors.

[Conventional technology]

Electrophotographic image formation using an electrophotographic selenium photoreceptor (hereinafter also simply referred to as photoreceptor) as an image forming member generally involves the following steps:
Charging of the photoconductor surface in the dark by corona discharge, formation of an electrostatic latent image by image exposure on the charged photoconductor surface, development of the formed latent image with toner, and transfer of the developed toner image to paper The process involves transferring the image, separating the paper on which the image has been transferred from the surface of the photoreceptor, and fixing the toner image on the paper. after being used for reuse.

In such a process, the surface charging potential of the photoreceptor in the charging step is generally set to 600V to 1000V. Conventionally, the thickness of the photosensitive layer of a photoreceptor was usually 50 μm to 60 μm. Therefore, in this case, the charged potential per 1 μm of thickness of the photosensitive layer is 11V to 17V.
Met.

[Problem to be solved by the invention]

If an attempt is made to charge the surface of the photoreceptor to such a high potential by corona discharge, if there is a defect in the photosensitive layer, a so-called lightning strike will occur in the defective area, causing dielectric breakdown and a large current flowing, damaging the photosensitive layer. The forming selenium-based photoconductive material melts, creating holes that reach the substrate, which causes image defects, and conventionally, about 10% of image defects were caused by such lightning strikes.

This invention was made in view of the above points, and
It is an object of the present invention to provide a selenium photoreceptor for electrophotography in which the occurrence of lightning strikes is suppressed and image defects caused by lightning strikes are reduced.

[Means to solve the problem]

In order to achieve the above object, according to the present invention, in an electrophotographic photoreceptor including a photosensitive layer made of a selenium-based photoconductive material, the film thickness of the photosensitive layer is set as necessary for image formation on the photoreceptor. The selenium photoreceptor for electrophotography has a thickness in which the charged potential per 1 μm of film thickness is in the range of 5 V or more and 9 V or less when charged to a certain potential.

[Effect]

By making the thickness of the photosensitive layer thicker than before and lowering the charged potential per 1 μm of film thickness from the conventional range of IIV to 17V to the range of 5V to 9V,
It is possible to suppress the occurrence of lightning strikes.

〔Example〕

A photosensitive layer is formed by vacuum depositing a selenium-based photoconductive material 1, such as ^s, Se, on a conductive substrate 9, such as an aluminum alloy substrate. At that time, photoreceptors with photosensitive layers having various thicknesses were produced by changing the amount of vapor deposition. Image reproduction tests were conducted on these photoreceptors, and the relationship between the number of image defects caused by lightning and the charge potential per 1 μm of photosensitive layer thickness was investigated, and the results shown in FIG. 1 were obtained. It can be seen from FIG. 1 that the number of image defects increases as the charged potential per 1 μm of photosensitive layer thickness increases, and in particular increases rapidly when the charged potential per 1 μm exceeds IOV. By setting the charge potential per 1 μm to 9 V or less, the number of image defects can be efficiently reduced. During image formation, the photoreceptor is normally used with a charging potential in the range of 600V to 1000V. When the charged potential of the photoreceptor is 600 V, the thickness of the photosensitive layer required to keep the charged potential per 1 μm to 9 V or less is 67 μm, and it is preferable to make the film thicker than this.

However, in order to increase the film thickness, there are problems such as the amount of vapor deposition material used increases and the vapor deposition time becomes longer, so the practical limit is about 120 μm, and in this case, the film thickness is 1 μm.
The charged potential around this point is 5V. In addition, the film thickness is 120 μm
Even if the charged potential of the photoreceptor is 1000 V,
The charged potential per μm is 8.3V, which is 9V or less.

Therefore, setting the charge potential per 1 μm of the photosensitive layer in the range of 5 V or more and 9 V or less (Ill: range of 67 μm or more and 120 μm or less) is suitable for reducing image defects caused by lightning strikes.

〔Effect of the invention〕

According to this invention, the thickness of the photosensitive layer of the selenium photoreceptor for electrophotography is increased so that the photoreceptor has a charge potential of 5 V or more and 9 V or less per 1 μm of the photosensitive layer during image formation. By setting such a charged potential, lightning strikes on the photosensitive layer are suppressed, and the occurrence of image defects caused by lightning strikes is reduced compared to the conventional 171
It is possible to obtain a selenium photoreceptor for electrophotography that can be significantly reduced to about 0.

[Brief explanation of the drawing]

Figure 1 shows the charged potential cylinder 1 per 1 μm thickness of the photosensitive layer.
figure

Claims (1)

[Claims] 1) In an electrophotographic photoreceptor equipped with a photosensitive layer made of a selenium-based photoconductive material, when the photoreceptor is charged to a potential necessary for image formation, the charge per 1 μm of the film thickness of the photosensitive layer increases. 1. A selenium photoreceptor for electrophotography, which has a thickness in a range of 5V or more and 9V or less.