JPH0216913B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a functionally separated selenium/tellurium photoreceptor. 2. Description of the Related Art Photoreceptors for electrophotography, in which a photosensitive layer made of an alloy mainly composed of selenium as a photoconductive material is formed on a conductive substrate, are used in a wide range of fields including copying machines. Recently, in this type of photoreceptor, a carrier is generated by light for the purpose of reducing characteristic fluctuations caused by repeated copying cycles, that is, increases in residual potential and decreases in charged potential called fatigue phenomenon, and improving its temperature characteristics. A so-called functionally separated multilayer photoreceptor has become common, in which a layer (charge generation layer or CGL) for transporting holes is separated from a layer (charge transport layer or CTL) for transporting holes in generated carriers. To form such a laminated photosensitive layer, after the first layer serving as CTL has been evaporated, the vacuum state of the vacuum deposition tank is broken, and then the second layer, CGL, is evaporated.
Alternatively, the evaporation sources for both the CTL and CGL layers are arranged side by side in a deposition tank, and a shutter mechanism is installed above each evaporation source, so that the shutter of one evaporation source is closed and the evaporation by the other evaporation source is performed. There are known ways to do it. However, with these techniques, for example, in the former case, there is a problem of the generation of surface defects due to an increase in the deposition time and the deterioration of the surface condition due to breaking the vacuum state, and in the latter case, It is extremely difficult to prevent selenium from adhering to the shutter mechanism and increasing defects on the surface of the photosensitive layer due to re-evaporation. An object of the present invention is to eliminate such drawbacks of conventional multilayer deposition, and to present a method for manufacturing a photoreceptor with few surface defects and extremely excellent cycle characteristics. The purpose of this is to laminate multiple selenium-tellurium alloy layers with different composition ratios on a substrate.
Evaporation sources of selenium-tellurium alloys of various composition ratios are placed side by side in one vacuum evaporation tank, and the evaporation is performed sequentially while maintaining the temperature of the evaporation sources other than the evaporation source corresponding to the layer to be evaporated in the range of 200 to 300℃. It is achieved by doing. Examples and comparative examples of the present invention will be described below with reference to the drawings. FIG. 1 shows an apparatus for an example and a comparative example, in which a conductive base (substrate) 3 of a photoreceptor is mounted on a cylindrical support shaft 2 arranged in the axial direction of a cylindrical vacuum chamber 1. The temperature is maintained at a constant temperature by a temperature control system (heater, water or liquid temperature control) provided inside the support shaft 2. Two evaporation sources 4 and 5 are located below the substrate 3 for the first and second layers. a shutter 6 provided above the evaporation sources 4 and 5;
7 is for a comparative example and is not used in the examples of the present invention. Example 1 A mirror-finished aluminum drum with a diameter of 120 mm and a length of 288 mm was oxidized with a nitric acid solution, and then installed on the support shaft 2 in the apparatus shown in Figure 1.
The temperature was maintained at 65°C. Evaporation source 4 includes
1500 granulated Se/Te alloy with Te5wt%
g. Also, put 500g of 13.5wt% Se/Te alloy into the evaporation source 5, first keep the temperature of the evaporation source 4 at 340℃ and the temperature of the evaporation source 5 at 250℃, and heat the first layer for about 40 minutes. After the vapor deposition, the temperature of the evaporation source 4 was lowered and maintained at 250°C, and at the same time the temperature of the evaporator 5 was raised by 350°C, and after evaporation was performed for about 20 minutes, it was removed from the vacuum chamber and its electrical characteristics, appearance, and image were measured. I checked the characteristics. Example 2 Manufacturing was carried out under the same conditions as in Example 1 except that the concentration of the Se/Te alloy in the first layer was 2.0 wt%. Comparative Example Vapor deposition was carried out using the same material as in Example 1, but the vapor deposition was controlled by opening the shutter 6 and closing the shutter 7, setting the temperature of the evaporation source 4 to 340°C, and depositing the first layer. After completing the vapor deposition, the shutter was opened and the temperature of the evaporation source 5 was set at 350° C. to perform vapor deposition of the second layer. The results of the electrical characteristics, appearance, and image characteristics of the photoreceptor obtained in the above Examples and Comparative Examples are shown in the first example.
Shown in the table. In each example, the number of samples was n=50, and only the image test was performed on n=10 of them.

[Table] In Table 1, Vs is the average value of surface potential (V),
E1/2 is the average value of half-attenuation exposure (lx·sec), and the evaluation method in the image test is as shown in Table 2.

[Table] In Table 1, the electrical characteristics are average values,
Although the standard deviation σ shows almost the same results, there are clearly significant differences between the example and the comparative example in terms of appearance and image test. The reason why surface defects can be reduced by the present invention is that the temperature of the evaporation sources other than those corresponding to the layer to be evaporated is set to 200°C, which is close to 250°C, which corresponds to the vacuum vapor pressure of 10 ^-4 of the Se/Te alloy. By maintaining the temperature above, Se/Te alloy is prevented from adhering to the evaporation source.
The purpose is to prevent the formation of defects on the surface of the photosensitive layer due to re-evaporation. However, if this holding temperature exceeds 300° C., the deposited layer may crystallize due to the influence of thermal radiation on the photoreceptor, which is not preferable. As described above, in the vapor deposition process of a selenium/tellurium photoreceptor having a multilayer structure, the temperature of the vapor deposition sources other than the current vapor deposition source is maintained in the range of 200 to 300°C, thereby increasing the temperature of the photosensitive layer surface. It eliminates negative effects, there is no need to break the vacuum state during the process, there is no need to introduce a complicated mechanism such as a shutter, and it is possible to improve the production yield of photoreceptors simply by controlling the temperature of the evaporation source. . Of course, the present invention is not limited to a two-layer structure, but can also be applied to a photoreceptor having a multilayer structure of three or more layers, and its effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a vacuum evaporation apparatus for an example of the present invention and a comparative example. 1... Vacuum chamber, 3... Substrate, 4, 5... Evaporation source.

Claims (1)

[Claims] 1. When laminating multiple selenium-tellurium alloy layers with different composition ratios on a substrate, evaporation sources for selenium-tellurium alloys with different composition ratios are placed side by side in one vacuum evaporation tank, and the evaporation sources correspond to the layers to be deposited. A method for manufacturing a multilayer selenium/tellurium photoreceptor for electrophotography, characterized in that deposition is carried out sequentially while maintaining the temperature of a deposition source other than the evaporation source within a range of 200 to 300°C.