JPS6090341A - Selenium photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To suppress an increase in residual potential in the stage of continuous repetitive use and to prevent decrease in image quality by incorporating specific concn. of oxygen into a charge transport layer out of the vapor deposition layer consisting of selenium (alloy) provided on a conductive base. CONSTITUTION:Selenium (alloy) evaporated from a vapor source 2 for selenium or selenium alloy (e.g.; selenium-tellurium) is deposited by evaporation on a conductive base body 1 which is an aluminum cylinder, etc. to form a vapor deposition layer. A vapor source 3 for selenium oxide is disposed in addition to the source 2 and the selenium (alloy) and the selenium oxide are simultaneously evaporated to form a charge transfer layer distributed uniformly with 100-200 ppm oxygen in the stage of forming the charge transfer layer. The intended selenium photosensitive body for electrophotography is thus botd. The level to trap the charge is thus decreased and the increase in the residual potential in the stage of using continuously and repetitively said body in copying is suppressed to <=1/10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a selenium photoreceptor for electrophotography, in which a photosensitive layer is formed by vapor deposition of a selenium-based material.

[Prior art and its problems]

Selenium photoreceptors for electrophotography are made by depositing high purity (99.99% or more) amorphous selenium or a selenium alloy such as selenium-tellurium on a conductive support usually made of aluminum.
It is formed by vapor deposition by heating to about 250 to 400° C. in a vacuum of about 10 liters. One of the properties required of a photoreceptor is that it should be able to sufficiently retain the surface charge (charged potential) applied to the photosensitive layer in the dark, and that the surface charge should quickly disappear during light exposure.
Furthermore, the fatigue phenomenon in which the potential of the photoreceptor after exposure, that is, the residual potential increases when this charging and exposure is repeated, must be reduced. If the residual potential is high, phenomena such as scumming, density reduction, and ghosting appear in actual images, and image quality deteriorates in continuous copying. This is mainly due to the fact that charges generated during light irradiation are captured in trap levels during transport. The higher the trap level density, the higher the residual potential of the photoreceptor, and in the process of repeated copying, charges are accumulated and the residual potential increases, leading to the above-mentioned deterioration of image quality.

[Purpose of the invention]

In contrast, it is an object of the present invention to provide a selenium photoreceptor for electrophotography that has excellent cyclic fatigue characteristics and does not have an increase in residual potential.

[Key points of the invention]

The present invention provides that one of the vapor deposited layers of selenium or selenium alloy of a selenium photoreceptor for electrophotography is a layer that participates in charge transport.
The above objective is achieved by including 00-200 pPm of oxygen.

[Embodiments of the invention]

When forming the charge transport layer of the functionally separated photoreceptor as an embodiment of the present invention, as shown in FIG. Another evaporation source 3 is filled with selenium oxide. The vacuum degree of the evaporation tank is set to 10-5 torr or more, and the heating temperature of evaporation sources 2 and 3 is set to 2.
The raw materials of both evaporation sources are simultaneously evaporated at 50 to 400°C and 200 to 300°C to obtain a carrier transport layer in which oxygen is uniformly distributed. In the case of a photoreceptor having a single photosensitive layer, an oxygen-containing photosensitive layer can be formed in the same manner.

FIG. 2 is a diagram showing fatigue properties, where dashed lines 21 and 23 indicate 5.5% oxygen containing ioo to 200 ppm of oxygen according to the present invention.
A charge transport layer made of a 5e-Te alloy containing 5% Te by weight and having a thickness of ωμm, and a 5e-Te alloy containing 5% Te and having a thickness of ωμm.
In the case of a functionally separated photoreceptor having a charge generation layer of 5 μm, the dashed line 21 indicates the residual potential, the dashed line indicates the charged potential before exposure, and the solid lines 22 and 274 indicate that no oxygen is added to the charge transport layer.
The residual potential and pre-exposure charging potential of a photoreceptor having an oxygen content of 10 ppm or less and having the same structure are shown, respectively.

In the embodiment of the present invention, compared to the conventional example, there is almost no variation in the charge potential before exposure, and the residual potential level, which should pose a problem in terms of image quality, is suppressed to about 1/10.

〔Effect of the invention〕

According to the present invention, when a charge transport layer of a functionally separated photoreceptor made of selenium or selenium-tellurium or a photosensitive layer of a single-layer photoreceptor contains oxygen at a concentration of 100 to 200 ppm, the level for trapping charges decreases. In actual copying, the increase in residual potential during continuous repeated use is reduced to 1/10.
It is possible to suppress phenomena such as background fogging, density reduction, and ghosting to less than 100%, and to provide good images for a long time. Therefore, it can be effectively applied not only to photoreceptors for PPC copiers, but also to printers, intelligent copiers, and the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a vapor deposition method according to an embodiment of the present invention, and FIG. 2 is a fatigue characteristic diagram of a photoreceptor according to an embodiment of the present invention and a conventional example when photographed on a repeating table. ■ Aluminum cylinder, 2 Selenium or selenium-tellurium alloy M'Rv i)+i, 3 Selenium oxide evaporation source. Figure 1

Claims (1)

[Scope of Claims] 1) Of the vapor deposited layers made of selenium or selenium alloy provided on the conductive substrate, the layer participating in charge transport is 100 to 100%
A selenium photoreceptor for electrophotography, characterized in that it contains 200 Ppm of oxygen.