JPH04295854A - Separated function type selenium photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To suppress the crystal at the boundary between a conductive substrate and charge transfer layer which is the cause for ground fogging by providing an under coat layer consisting of selenium-tellurium-arsenic between the conductive substrate and the charge transfer layer. CONSTITUTION:The under coat layer 5 consisting of the selenium-tellurium- arsenic is provided at the boundary between the conductive substrate 1 and the charge transfer layer 2. Unnecessary negative electrostatic charges are increased in electrophotographic process and an inter-paper history remains in the images of the 2nd and subsequent sheets when continuous printing is executed with cut paper. Since such inter paper history adversely affects the image quality, the addition of the tellurium is needed. The arsenic is required to be added at 1 to 3% and the amt. of the tellurium to be added is preferably 10 to 20%. The stable surface charges are obtd. and the ground fogging of the background is prevented by selecting the above-mentioned materials.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functionally separated selenium photoreceptor for electrophotography, and more particularly to a functionally separated selenium photoreceptor for a reversal development type electrophotographic apparatus.

0002

2. Description of the Related Art Laser beam printers, which have become increasingly popular in recent years, use a conductive substrate (1), as shown in FIG.
So-called functionally separated selenium photoreceptors are often used, which are composed of a charge transfer layer (2), a charge generation layer (3), a surface protection layer (4) provided as necessary, and the like. In addition, the development method is a reversal development method, which is the opposite of the regular development method widely used in conventional electrophotographic copying machines that forms an image with the exposed area as a white background, in which toner is attached to the exposed area. The so-called reversal development method, in which an image is formed using an unexposed area as a white background area, is widely used.

0003

By the way, in the above-mentioned laser beam printer, toner particles having a smaller particle size (10 μm or less) are being used as resolution becomes higher. Toner with a small particle size is essential for high resolution, but on the other hand, in the electrophotographic process using reverse development, even the slightest disturbance in the surface potential during charging can be used for development, so the surface potential becomes extremely uniform. is required. That is, if there is a part where the surface potential is low during charging, that part will be developed thinly and "background fog" will occur on the image. Excluding defects in appearance, the cause of minute disturbances in surface potential is often caused by non-uniform crystalline state at the interface with the conductive substrate during lamination of selenium films. As crystallization progresses in an amorphous semiconductor, dark resistance decreases, making it difficult to maintain surface potential. However, since the crystallization at the interface is sensitively affected by the substrate temperature and the temperature of the material to be deposited, it is considered extremely difficult and impossible to make this crystalline state uniform. To solve these problems, it is necessary to suppress crystallization at the interface. One possible means of suppressing crystallization is to lower the temperature of the substrate, but this is an inappropriate method because it not only increases the residual potential but also deteriorates the adhesion between the substrate and the deposited film.

0004

[Object of the Invention] An object of the present invention is to provide a functionally separated selenium photoreceptor that improves charge stability on the surface of the photoreceptor and prevents background fogging that occurs due to uneven surface charge. .

[0005]

[Means of the present invention for solving the problems] The present invention is based on FIG.
As shown in the figure, an undercoat layer (
5), it was discovered through experimental research that crystallization at the interface between the substrate and the charge transfer layer can be suppressed and an extremely stable surface potential can be obtained. In this case, if the amount of arsenic added is too large, unnecessary negative charge will increase in the electrophotographic process, and when continuous printing is performed on cut paper, inter-paper history will remain on images from the second sheet onward, which will adversely affect image quality. Therefore, it is necessary to add tellurium. It has been revealed that the amount of arsenic added is required to be 1% to 3%, and the amount of tellurium added is preferably 10% to 20%. By selecting these appropriately, a stable surface charge can be obtained and It is possible to prevent ground fogging. Next, examples of the present invention will be described.

[0006]

[Example] [Example 1] On a cylindrical conductive aluminum substrate, 15% tellurium and 3 arsenic were used as an undercoat layer.
%, a selenium-tellurium-arsenic alloy layer with a film thickness of 5 μm is deposited, and high-purity selenium (purity of 99.999% or more) is deposited on top of it.
Alternatively, a 40 μm thick charge transfer layer made of selenium-halogen was deposited. Furthermore, on top of that, the tellurium concentration is 50
A charge generation layer made of a selenium-tellurium alloy with an arsenic concentration of 2% and a thickness of 0.3 μm, and a surface protective layer made of a selenium-arsenic alloy with an arsenic concentration of 2% and a thickness of 4 μm were formed on the uppermost layer by vapor deposition. [Example 2] The undercoat layer was formed in the same manner as in Example 1 except that the arsenic concentration in the undercoat layer was changed to 0.5%. [Example 3] The undercoat layer was formed in the same manner as in Example 1 except that the arsenic concentration in the undercoat layer was changed to 8%. [Example 4] The tellurium concentration of the undercoat layer was reduced to 5%. The other parts were formed in the same manner as in Example 1. [Example 5] The thickness of the undercoat layer was changed to 10 μm, and a charge transfer layer of 35 μm was deposited. The other parts were formed in the same manner as in Example 1. [Comparative example] High purity selenium (99.999%) was coated on a cylindrical conductive aluminum substrate without an undercoat layer.
or a charge transport layer of 45 μm thick made of selenium-halogen was deposited. The other parts were formed in the same manner as in Example 1. When image characteristics such as background fog and interpaper history were determined using toner having a particle size of 10 μm or less for each of the above Examples and Comparative Examples, the results shown in Table 1 were obtained. By interposing an undercoat layer made of selenium-tellurium-arsenic between the conductive substrate and the charge transport layer as in the present invention, the charging time in the electrophotographic process is improved compared to the conventional selenium-tellurium photoreceptor. It can be seen that the surface charge is stable and good images without background fog can be obtained even when a toner with extremely small particle size for high resolution is used.

[Table 1]

[0007]

[Effects of the Invention] As is clear from the above, according to the present invention, it is possible to obtain a functionally separated selenium photoreceptor that can obtain good images without background fog even when using toner with an extremely small particle size. For example, it is highly effective as a photoreceptor for a laser beam printer.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a functionally separated photoreceptor according to the present invention.

FIG. 2 is a cross-sectional structural diagram of a conventional functionally separated photoreceptor.

[Explanation of symbols]

(1) Conductive substrate (2) Charge transfer layer (3) Charge generation layer (4) Surface protective layer (5) Undercoat layer

Claims (2)

[Claims] 1. A functionally separated selenium photoreceptor in which a charge transfer layer and a charge generation layer are sequentially formed on a conductive substrate, and a surface protective layer is provided as necessary, in which a charge transfer layer and a charge generation layer are provided between the charge transfer layer and the conductive substrate. A functionally separated selenium photoreceptor for electrophotography, characterized in that it is provided with an undercoat layer made of selenium-tellurium-arsenic. 2. The functionally separated selenium photoreceptor for electrophotography according to claim 1, wherein the undercoat layer has an arsenic concentration of 1 to 5% and a film thickness of 2 to 10 μm.