JPS6084545A - Selenium type electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve repetition fatigue resistance characteristics by incorporating silver in a layer for participating in transfer of carriers. CONSTITUTION:A layer for participating in transfer of carriers in the photosensitive layer of a functionally separated type selenium type photosensitive body is made of selenium or an Se-Te alloy contg. 5-10<3>ppm silver. For example, a photosensitive body is prepared by vapor depositing a selenium alloy contg. 5.5wt% Te and 50ppm silver to form a carrier transfer layer, and further, vappor depositing a selenium alloy contg. 25wt% Te on this layer to form a carrier generating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an electrophotographic photoreceptor having a photosensitive layer made of selenium or a selenium alloy.

[Prior art and its problems]

A selenium photoreceptor for electrophotography is made by heating high-purity selenium or a selenium alloy such as selenium-tellurium to a temperature of about 250 to 400°C in a vacuum of about 1 x 10 Torr on a conductive support made of aluminum or the like. It is formed by vapor deposition. As for the characteristics of an electrophotographic photoreceptor, it is desirable that the surface charge (electrostatic potential) applied to the photosensitive layer be sufficiently retained in the dark, and that the surface charge disappear quickly when exposed to light. It is required that there be no increase in the surface potential of the photoreceptor after exposure, that is, no increase in residual potential due to fatigue. 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 because carriers generated during light irradiation are captured in trap units during carrier transport. The surface potential of a photoreceptor with a high trap level density is also high, and in the process of repeated copying, a residual potential is accumulated on the surface of the photoreceptor, resulting in the above-mentioned deterioration of image quality.

[Purpose of the invention]

In view of this, it is an object of the present invention to provide a selenium photoreceptor for electrophotography with improved repeated fatigue characteristics.

[Key points of the invention]

The above object is achieved by forming a selenium containing selenium or a selenium-tellurium alloy. The layer participating in gear transport means the carrier transport layer in the case of a functionally separated type photoreceptor, and means the photosensitive layer itself in the case of a single layer photoreceptor.

[Embodiments of the invention]

In the embodiment of the present invention, carrier transport of a functionally separated photoreceptor on a support using an aluminum cylinder 1@(CTL)
A selenium alloy layer containing 5.5 wt. tellurium with 50 ppm silver i added was deposited as a single photosensitive layer. As shown in FIG. 1, two evaporation sources 2 and 3 are housed below a conductive support 1 rotatably arranged in a vacuum evaporation tank (not shown), and one evaporation source 2 is connected to the other evaporation source 2. The evaporation source 3 is filled with Be--Te alloy, which is the main component of the photosensitive layer, and the other evaporation source 3 is filled with Be--Te alloy. Set the total vacuum level of the evaporation tank to 10 torr or more, and set the evaporation source 2.3i to 250 to 450 for each.
Ag is uniformly distributed in the deposited layer by simultaneous heating to temperatures of 900 to 1100°C and simultaneous evaporation. As a function-separated photoreceptor, a carrier generation layer (C
A 6 μm thick vapor deposition layer was formed from a Be alloy containing 25% by weight of Te as GL).

FIG. 2 shows changes in charged potential and residual potential during continuous repeated copying. Chains [7121 and 23 respectively indicate the surface potential and residual potential of the functionally separated photoreceptor produced as described above, and the solid line 22.24 indicates the surface potential and residual potential when Ag is 1 ppm or less. From this figure, it can be seen that the photoreceptor according to the present invention has almost no fluctuation in pre-exposure charge potential than the photoreceptor to which no Ag is added, and the residual potential, which is a problem in image quality, is suppressed to a level of 1/2 or less. Therefore, a photoreceptor having a uniform concentration of Ag at a concentration of 50 ppm in the CTL can provide good images with low fatigue and less background fog, lower density, ghost, etc.

FIG. 3 shows the changes in the pre-exposure potential, the potential retention rate for 1 second after flashlighting (in the dark), and the residual potential after optical neutralization when the temperature of the copying product term was varied. 35 represents the temperature characteristics of a photoreceptor containing CTL lcAg at a concentration of 50 ppm according to the present invention, respectively;
6 shows the temperature characteristics of a photoreceptor with an Ag content of 1 ppm or less. The desired pre-exposure potential curve.

36 and charge potential retention curves 33.34 are at room temperature of 23°C.
It is expressed as a relative value when the measured value at the time of is set as 100. Figure 3 shows that the photoreceptor according to the present invention to which Shim G is added at a concentration of 50 ppm has almost no difference in temperature characteristics from conventional photoreceptors, and can be used in the same way as conventional photoreceptors from room temperature to high temperatures of about 50°C. It is clear that it is possible to do so. Furthermore, A
The addition of 1)g shows the same effect as long as it does not exceed 10 1)I)m.

The above results can be similarly obtained when Ai is added to pure Sθ instead of the Be-Te alloy, or when a single layer photoreceptor is used. Furthermore, the composition of the constituent elements of the layers other than the CTL does not matter.

〔Effect of the invention〕

The present invention reduces the number of CTLs or trap units that capture single a in a functionally separated photoreceptor, and provides a selenium photoreceptor for electrophotography with good fatigue characteristics during continuous repeated use. In addition to being applied to the body, it can also be applied to photoreceptors for printers and intelligent copiers, and the effects obtained are extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view conceptually showing an evaporation method for a photoreceptor according to an embodiment of the present invention, and FIG. 2 is a diagram showing fatigue characteristics of the photoreceptors according to an embodiment of the present invention and a comparative example due to repeated use. FIG. 3 is a diagram similarly showing temperature characteristics. 1... Conductive support, 2... Be-Te alloy evaporation source, 3... Ag evaporation source. 6-

Claims (1)

[Claims] 1) The layer that participates in carrier transport in the photosensitive layer contains 5 to 10 silver.
A selenium photoreceptor for electrophotography, characterized in that it is made of selenium or a selenium-tellurium alloy containing 3 ppm of selenium.