JPH10239883A - Electrophotographic organic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic org. photoreceptor having satisfactory photosensitivity and almost free from unevenness by specifying the light reflectance of the surface of an electrically conductive substrate. SOLUTION: A photosensitive layer 2 is formed on the surface of an electrically conductive substrate 1 having 80-95% light reflectance to obtain the objective electrophotographic org. photoreceptor. The substrate 1 is made of an Al-base material and the surface is preferably mirror-finished. An electric charge generating material in the photosensitive layer 2 is preferably a phthalocyanine compd. Light for exposure radiated on the photoreceptor passes the electric charge transferring layer 22, reaches the electric charge generating layer 21 and is absorbed. Since the thickness of the electric charge generating layer 21 is <=1μm and the org. photosensitive layer has a low absorption factor, about 70% of the light is absorbed and the remainder reaches the surface of the substrate 1. Sensitivity in the electrophotographic org. photoreceptor having high light transmissivity can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate, which is used for a copying machine, a printer and the like.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view of a function-separated type electrophotographic organic photoreceptor. The charge generation layer 21 is formed on the conductive substrate 1.
1 and the charge transport layer 22 are stacked. Positive charges uniformly charged on the surface of the charge transport layer 22 (for example, the signs are opposite for electrons which are positively charged and have the same mechanism), in the exposed portion of the charge generation layer 21, Of the electron-hole pairs generated by light in the charge generation layer 21, they are neutralized by the electrons that have moved through the charge transport layer 22, and remain in the unexposed portions. As a result, a density of electric charge, that is, an electrostatic latent image is obtained. The evaluation of the electrostatic latent image is evaluated based on the surface potential of each part. Further, the sensitivity of the photoreceptor is represented by an exposure amount necessary for lowering the surface potential from a constant to a predetermined surface potential, and this is also called light sensitivity.

A conventional conductive substrate is aluminum (hereinafter, referred to as Al) containing additives such as Si, Mg, and Mn. The surface of the substrate is subjected to alumite treatment to improve the adhesion of the photosensitive layer. In addition, the injection of charges from the conductive substrate has been suppressed.

[0004]

However, even in the case of photosensitive layers having the same characteristics, the photosensitivity may not be constant with respect to a constant charged voltage and may vary depending on the alumite treatment.
An object of the present invention is to provide an electrophotographic organic photoreceptor having good photosensitivity and small variation.

[0005]

In order to achieve the above object, an electrophotographic organic photoreceptor having a photosensitive layer formed on the surface of a conductive substrate has a light reflectance of 80% on the surface of the substrate.
% To 95%. The base is made of a material mainly composed of aluminum, and its surface is preferably mirror-finished.

The charge generating material in the photosensitive layer is preferably a phthalocyanine compound, and the charge transporting material is preferably a hydrazone compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, variations in light sensitivity
It is mainly based on the fact that it has been found out that it is caused by variations in the light reflectance of the surface of the conductive substrate. The exposed light to the photoreceptor penetrates the charge transport layer and is absorbed by the charge generation layer. However, the thickness of the charge generation layer is 1 μm or less, and the absorption rate of the organic photosensitive layer is small, so the absorption is small. Is 7
It is about 0%. Since the remaining 30% reaches the conductive substrate surface and is reflected according to the reflectance of the conductive substrate surface,
The effect of reflectance is significant.

FIG. 2 is a graph schematically showing the dew light intensity in the photosensitive layer. The horizontal axis is the thickness of the photosensitive layer, and the vertical axis is the logarithm of the light intensity. There is no absorption in the charge transport layer,
The incident intensity on the charge generation layer is set to 1. a is when the reflectance of the surface of the conductive substrate is large, and b is when the reflectance is small. The curves are far apart due to reflection loss at the surface of the conductive substrate.

In the case of the Se / Te-based photosensitive layer, the absorptance is large and the film thickness is large, so that only about 10% reaches the surface of the conductive substrate, and reflected light does not matter. Example 1 A machined surface of an Al conductive substrate was subjected to mirror finish and Compax finish, and after measuring the reflectance, a photosensitive layer was formed. The charge generation layer was made of phthalocyanine as a charge generation material and had a thickness of 0.2 μm, and the charge transport layer was made of hydrazone as a charge transport material and had a thickness of 20 μm.

When the same conductive layer surface was subjected to alumite treatment and the same photosensitive layer was formed, a comparison was made between the adhesion strength of the photosensitive layer and the case where the present invention was used. It was not enough. The prepared photoreceptor was mounted on a printer, charged to -650 V, and the exposure required for a potential of 100 V was determined.

Table 1 shows the relationship between the reflectance and the exposure.

[0012]

[Table 1] From Table 1, it can be seen that the mirror finish provides high reflectivity. As a result, the reflectance of the conductive substrate surface becomes 85%.
In the above case, the sensitivity is good (the exposure amount is small), and the dependency of the sensitivity on the reflectance is small, that is, the variation in the sensitivity is small.

[0013]

According to the present invention, in an electrophotographic photoreceptor in which a photosensitive layer is formed on the surface of a conductive substrate, the light reflectance of the surface of the substrate is set to 80% to 95%, so that the light is transmitted through the charge generating layer. 30% of the exposed sunlight contributed to the sensitivity,
The sensitivity of the electrophotographic organic photoreceptor having a good light transmittance is improved.

Further, since the conductive base is made of a material mainly composed of aluminum and its surface is mirror-finished, the above high light reflectance can be easily realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a function-separated type electrophotographic organic photoreceptor.

FIG. 2 is a graph schematically showing the dew light intensity in a photosensitive layer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 photosensitive layer 21 charge generation layer 22 charge transport layer

Claims (3)

[Claims] 1. An electrophotographic organic photoreceptor having a photosensitive layer formed on the surface of a conductive substrate, wherein the substrate has a light reflectivity of 80% to 95%. 2. The electrophotographic organic photoreceptor according to claim 1, wherein said base is made of a material mainly composed of aluminum, and a surface thereof is mirror-finished. 3. The electrophotographic organic photoreceptor according to claim 1, wherein the charge generating material in the photosensitive layer is a phthalocyanine compound, and the charge transporting material is a hydrazone compound.