JP2775477B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a selentellur-based photoconductor for function-separated electrophotography.

(Prior Art and Problems Thereof) A charge transfer layer (2) and a charge generation layer (3) are formed on a function-separated type selentelluride photoconductor for electrophotography, that is, a conductive substrate (1) as shown in FIG. The separable-type selentellurium-based photoconductor is widely used as an electrophotographic copying machine such as a copying machine or a printer equipped with a short-wavelength light source of 600 nm (or less), which has a suitable chargeability, sensitivity, and life. Practical.

However, this photoreceptor, on the other hand, has weaknesses in so-called environmental preservation such as high temperature resistance and high humidity resistance, which are significantly inferior to other photoreceptors. For example, when a foreign object comes into contact with or adheres to the surface, It has a weak point of shifting from an amorphous state to a more stable crystalline state. In order to prevent this, a number of technologies have been announced to improve the environmental preservation by adding, for example, arsenic (As) to the charge generating layer which is the surface layer of the photoreceptor and further to the entire layer. I have.

Although these methods can certainly improve the environmental preservation property, on the other hand, they cause a new problem that the chargeability and sensitivity of the selentelluric photoreceptor before the addition of arsenic cannot be maintained. As a result, image quality is degraded.

(Object of the Invention) The present invention provides a selentellur-based photoreceptor for electrophotography for electrophotography which not only has excellent environmental resistance but also has electrophotographic characteristics almost equivalent to those of a selentelluride-based photoreceptor to which arsenic is not added. It is the purpose.

(Means of the Invention for Solving the Problems) To prevent the deterioration of electrophotographic characteristics due to the addition of arsenic performed to improve environmental resistance, the amount of arsenic added is reduced and the surface layer is replaced. Means for increasing the thickness of the charge generation layer is considered. However, in general, when the thickness of the charge generation layer is increased, the residual potential is sharply increased at a certain thickness or more as shown in FIG. Therefore, the increase in membrane pressure is limited, and it is difficult to obtain the required environmental preservation by this method.
This means is not practical.

In addition, the thickness of the charge generating layer is reduced to a range where a residual potential that can be practically used is obtained, and the lack of environmental preservation due to the reduced thickness is satisfied by adding an appropriate amount of arsenic. Means are conceivable. However, this method cannot prevent a partial change in sensitivity due to a partial scratch caused during development, transfer, cleaning, or the like as the film thickness becomes thin. Therefore, it is unavoidable to cause a problem on the service life in terms of image quality.

However, if in this method even if the charge generation layer is partially damaged as described above, if the sensitivity of the photoreceptor is not changed and the image is not affected, the film thickness may be reduced. The problem of life is greatly improved, and the required environmental preservation can be obtained by adding arsenic.

The present invention has solved the above-mentioned problem of life by the following means. The selenium telluride-based photoreceptor controls the photosensitive wavelength region by adding tellurium to selenium. In a function-separated type photoreceptor, the 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 was added to the charge generation layer and the charge transfer layer, and the amount of tellurium added to both layers was the same, it hardly affected the photosensitive wavelength region and other characteristics. .

In the present invention, the charge generation layer on the surface and the charge transfer layer provided so as to be located thereunder are made to have the same concentration of tellurium, so that the charge generation layer on the surface and the charge transfer layer beneath the surface The light sensitivity is the same.

In this way, as described above, even if the surface charge generation layer is partially scratched by abrasion due to mechanical stress such as development and cleaning, and the film thickness is partially reduced, the charge generation layer and Since there is no tellurium concentration difference between the charge transfer layer and the sensitivity of both layers, there is no influence on the image, so that the life can be extended accordingly. Therefore, it is possible to provide a function-separated type electrophotographic photoconductor having excellent environmental preservation properties and having electrophotographic characteristics and a life almost similar to those of the selentellurium-based photoconductor. Next, examples will be described.

Example A 50-μm thick selenium-tellurium alloy containing 4% by weight of tellurium was deposited on an aluminum substrate to form a charge transfer layer, and then 4% by weight of tellurium and 1.5% by weight of arsenic were formed thereon.
Was added to form a charge generation layer by vapor deposition to a thickness of 0.8 μm to form a charge generation layer. Next, in sample A, the amount of tellurium added to the charge generation layer was set to 8% by weight. Samples with the same conditions
B, and further, sample A in which arsenic was not added to the surface charge generation layer in sample A was used as sample C, and the environmental preservation property, image characteristics and life characteristics were confirmed by using an actual machine, and the results shown in Table 1 were obtained.

The relationship between the residual potential and the thickness of the charge generation layer was determined using the amount of arsenic added as a parameter, and the results shown in FIG. 2 were obtained. As is clear from this, when the added amount of arsenic is 5% by weight, when the film thickness exceeds 1 μm, the residual potential rapidly increases to 100 V or more. When the amount of arsenic added is 3% by weight or less, the film thickness becomes 2 μm.
Beyond m, the residual potential rapidly increases to over 100 volts. Therefore, in view of the residual potential of several tens of volts normally allowed for the photoreceptor, the best region allowed is the case where 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 the table, Sample A in which the film thickness and the amount of arsenic added fall within the ranges is the most excellent in environmental preservation, image and life characteristics. Also, as in the case B, if the amount of tellurium is large, the service life is shortened. It is known that the addition of an appropriate amount of halogen is effective for lowering the residual potential, but the residual potential is further reduced by adding 1000 ppm or less of halogen to the charge transfer layer also in the photoreceptor of the present invention. It is possible to provide a photosensitive member having good image quality.

(Effects of the Invention) As is apparent from the above description, according to the present invention, a selentelluride-based electron having good environmental preservability and good life characteristics suitable for use in an electrophotographic apparatus such as a copier printer equipped with a short wavelength light source such as an EL light source. A photoreceptor can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a function-separated type electrophotographic photoreceptor, and FIG. 2 is a diagram showing a relationship between a residual potential of a photoreceptor and a film thickness of a charge generation layer. (1) ... conductive substrate, (2) charge transfer layer, (3) ... charge generation layer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-149046 (JP, A) JP-A-58-5748 (JP, A) JP-A-57-157252 (JP, A) JP-A-57-157 155545 (JP, A) JP-A-62-54270 (JP, A) JP-A-63-36260 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/08 101

Claims (2)

(57) [Claims] An amount of arsenic added to a charge generation layer in a two-layered electrophotographic photoreceptor having a charge transfer layer and a charge generation layer on a conductive substrate such that the charge generation layer is located on the surface. 0.5 to 5%, and the arsenic addition amount of the charge transfer layer is 3
%, The charge generation layer has a film pressure of 2 μm or less, and the charge generation layer and the charge transfer layer have the same amount of tellurium addition of 5% or less, respectively. 2. The electrophotographic photosensitive member according to claim 1, wherein a halogen is added to the charge transfer layer at a concentration of 1000 ppm or less.