JPH0371145A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To render the same photosensitivity to an electric charge generating layer as a surface layer and an electric charge transferring layer as a lower layer and to provide an Se-Te type electrophotographic sensitive body having satisfactory shelf stability in the environment and a long service life by making the concn. of Te in the electric charge generating layer equal to that in the electric charge transferring layer. CONSTITUTION:The amt. of As in an electric charge generating layer 3 is regulated to 0.5-5% and that in an electric charge transferring layer 2 to <=3%. The thickness of the layer 3 is regulated to <=2mum and the amt. of Te in the layer 3 is made nearly equal to that in the layer 2 and regulated to <=5%. Even when the layer 3 as a surface layer is partially scratched by mechanical stress due to development, cleaning, etc., and the thickness of the layer 3 is partially reduced, a formed image is not affected and service life can be pro longed because the layers 3, 2 has the same sensitivity due to no difference in the concn. of Te between the layers 3, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a functionally separated type selenite photoreceptor for electrophotography.

(Prior art and its problems) A selenite-based photoreceptor for electrophotography of a functionally separated type, that is, the first
As shown in the figure, a functionally separated selenium-based photoreceptor consisting of a charge transfer layer (2) and a charge generation layer (3) formed on a conductive substrate (1) generally uses a short wavelength light source of 600 nm (or less). It has been widely put into practical use because it has suitable chargeability, sensitivity, lifespan, etc. for use in electrophotographic copying devices such as copying machines and printers.

However, on the other hand, this photoreceptor has the disadvantage that it is significantly inferior to other photoreceptors in terms of so-called environmental preservation properties such as high temperature resistance and high temperature resistance.For example, when foreign matter comes into contact with or adheres to its surface, it easily It has the weakness of transitioning from an amorphous state to a more stable crystalline state. To prevent this, many technologies have been announced that attempt to improve environmental preservation by adding arsenic (As), for example, to the charge generation layer, which is the surface layer of the photoreceptor, and even to the entire layer. There is.

These methods certainly improve environmental preservation, but on the other hand, the charging properties that selenium-based photoreceptors had before the addition of arsenic.

This creates new problems such as the inability to maintain sensitivity, leading to deterioration of image quality.

(Objective of the Invention) The present invention provides a functionally separated electrophotographic selenite-based photoreceptor that not only has excellent environmental resistance but also has electrophotographic properties almost equivalent to selenite-based photoreceptors without the addition of arsenic. This is the purpose.

(Means of the present invention for solving the problem) In order to prevent the deterioration of electrophotographic properties due to the addition of arsenic to improve environmental resistance, the amount of arsenic added is reduced and a surface layer is One possible method is to increase the thickness of the charge generation layer.

However, in general, when the thickness of the charge generation layer is increased, as shown in FIG. 2, for example, the residual potential increases rapidly above the thickness, resulting in a deterioration of the electrophotographic characteristics.

Therefore, since there is a limit to the increase in film thickness, it is difficult to obtain the required environmental preservation properties depending on this method, and this means cannot be practically adopted.

In addition, the thickness of the charge generation layer is reduced within a range that allows a practically acceptable residual potential to be obtained, and the lack of environmental preservation due to the small thickness is attempted to be satisfied by adding an appropriate amount of arsenic. There are ways to think about it. However, with this method, as the film thickness becomes thinner, it is impossible to prevent scratches caused by local scratches caused during development, transfer, cleaning, etc., resulting in local changes in sensitivity. Therefore, it is unavoidable that problems in terms of image quality and longevity will arise.

However, in this method, even if the charge generation layer is partially scratched as described above, the sensitivity of the photoreceptor remains unchanged and the image is not affected, based on the reduction in film thickness. Life-span problems are significantly improved, and the addition of arsenic provides the required environmental stability.

The present invention solves the above-mentioned problem regarding lifespan by the following means. A selenium-tellurium photoreceptor is one in which the sensitive wavelength range is controlled by adding tellurium to selenium.
In a function-separated type photoreceptor, this control is mainly performed by adding tellurium to the charge generation layer on the surface. However, as a result of various studies, it was confirmed that even if tellurium is added to the charge generation layer and the charge transport layer, and the amount of tellurium added in both layers is the same, there is almost no effect on the photosensitive wavelength range or other characteristics. .

From the foregoing, the present invention makes it possible to make the tellurium concentration of the charge generation layer on the surface and the charge transfer layer located below the same to be the same, so that the charge generation layer on the surface and the charge transfer layer located below the charge transfer layer have the same concentration of tellurium. It is characterized by having the same light sensitivity.

In this way, as mentioned above, even if the surface charge generation layer is partially scratched due to scratches due to mechanical stress due to development, cleaning, etc. and the film thickness is partially thinned, the charge generation layer will remain intact. There is no tellurium concentration difference between the charge transfer layer and the sensitivity of both layers, which does not affect the image, so the service life can be extended accordingly. Therefore, it is possible to provide a functionally separated electrophotographic photoreceptor that has excellent environmental preservation properties and has electrophotographic properties and a lifespan almost similar to those of a selenium-based photoreceptor. Next, an example will be described.

(Example) A charge transfer layer was formed by depositing a selenium-tellurium alloy containing 4% by weight of tellurium on an aluminum substrate to a thickness of 50 pm, and then 4% by weight of tellurium was deposited on the aluminum substrate.

Sample A is a charge generation layer formed by vapor depositing a selenium tellurium arsenic alloy containing 1.5% by weight of arsenic to a thickness of 0.8 μm. 8% by weight and other conditions were the same as Sample B, and Sample A without the addition of arsenic in the surface charge generation layer was defined as C. Environmental preservation, image characteristics and life characteristics in actual equipment were determined for each. When confirmed, the results shown in Table 1 were obtained.

Further, when the relationship between the residual potential and the film thickness of the voltage generating layer was determined using the amount of arsenic added as a parameter, the results shown in FIG. 2 were obtained. As is clear from this, when the amount of arsenic added is 5% by weight, the residual potential increases rapidly to 100 V or more when the film thickness exceeds 1-. Further, when the amount of arsenic added is 3% by weight or less, the residual potential rapidly increases to 100 volts or more when the film thickness exceeds 2 cm. Therefore, considering the residual potential of several tens of volts normally allowed for photoreceptors, the best range allowed is when the thickness of the charge generation layer is 1 μm or less and the amount of arsenic added is 2.0% by weight or less. As shown in Table 1, Sample A whose film thickness and amount of arsenic added fall within these ranges has the best environmental preservation properties, image quality, and life characteristics. Furthermore, as in case B, if the amount of tellurium added is large, the life will be shortened, so it is preferable to limit the amount to about 5% or less.

It is known that adding an appropriate amount of halogen is effective in reducing the residual potential, but in the photoreceptor of the present invention, the residual potential can be further lowered by adding 11,000 pp or less of halogen to the charge transfer layer. It becomes possible to provide a photoreceptor with good image quality.

(Effects of the Invention) As is clear from the above, according to the present invention, a selenite-based material having good environmental preservation properties and life characteristics suitable for use in electrophotographic devices such as copiers and printers equipped with a short wavelength light source such as an EL light source is provided. A photoreceptor for electrophotography can be provided.

1st figure

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a function-separated type electrophotographic photosensitive layer, and FIG. 2 is a diagram showing the relationship between the residual potential of the photoreceptor and the thickness of the charge generation layer. (])...Conductive substrate, (2)...Charge transfer layer,
(3)...Charge generation layer. Figure 2 agent

Claims (2)

[Claims] (1) In a selenium-based electrophotographic photoreceptor with a two-layer structure comprising a charge transfer layer and a charge generation layer on a conductive substrate such that the charge generation layer is located on the surface, the amount of arsenic added to the charge generation layer is reduced to 0. .5 to 5%, the amount of arsenic added to the charge transfer layer is 3% or less, the thickness of the charge generation layer is 2 μm or less, and the amount of tellurium added to the charge generation layer and the charge transfer layer is approximately the same, 5% or less each. A photoreceptor for electrophotography characterized by the following. (2) The electrophotographic photoreceptor according to claim 1, wherein halogen is added to the charge transfer layer at a concentration of 1000 ppm or less.