JPH0261741B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the structure of an electrophotographic photoreceptor. 2. Description of the Related Art Photoreceptors in which a selenium (Se)-tellurium (Te)-halogen layer is provided on a conductive support have been known. By adding Te to this photoreceptor Se, the sensitivity wavelength is extended to the long wavelength side, increasing the sensitivity, and since Te is added to the entire layer, printing durability is improved. Furthermore, by adding halogen, the drawback of Se-Te alloys, such as high residual potential, is eliminated. However, when this halogen-added photoreceptor is subjected to continuous copying with a copying machine, the charged potential of the photoreceptor gradually decreases as the number of copies increases, and the density of the copied image also decreases, making it difficult to put it to practical use. Table 1 shows the results of investigating the cause of the gradual decrease in this charging potential. That is, Table 1 shows the Se (86% by weight) - Te (14% by weight) alloy on an aluminum drum.
Se (86% by weight) - Te (14% by weight) - Chlorine (30ppm)
This shows the difference in properties when deposited under the same conditions as the alloy. (The amount of chlorine added is based on the total amount of Se and Te as 100%.)

[Table] As can be seen from Table 1, the Se-Te-chlorine alloy has a low residual potential, but the drop in charging potential is extremely large. In addition, when measuring the Te concentration from the support side toward the surface of both photoreceptors, both photoreceptors had almost the same distribution. From these two facts, it was found that the cause of the large decrease in the charging potential was not due to the distribution state of Te, but due to the chlorine in the alloy, and theoretically,
By adding chlorine to Se-Te alloy, Se-
The resistivity of Te alloy becomes lower. As a result, Se−Te−
It is conceivable that a sufficient blocking layer for charge retention is not formed on the surface of a photosensitive layer made of chlorine. The present invention has been made in consideration of the above points, and an object of the present invention is to obtain a photoreceptor having a low residual potential and a stable charging potential. The present invention will be described above based on the drawings. FIG. 1 shows a sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention. In the figure, 1 is a conductive support, 2 is a first layer of Se-Te-halogen having a thickness of 20 to 80 μm, and 3 is a second layer of Se-Te having a thickness of 2 to 10 μm. In this photoreceptor, the Te concentration of the first layer 2 is suitably 3 to 14%, and the Te concentration of the second layer 3 is suitably 3 to 25%.
If the Te concentration in the first layer 2 is less than 3%, the residual potential increases due to repetition, and if it is more than 14%, the resistance becomes too low and it becomes difficult to retain charge. In the second layer 3, if the Te concentration is less than 3%, the residual potential increases and only a low concentration can be obtained. while 25
If it exceeds %, dark decay may increase, which is undesirable. The thickness of the first layer 2 is 20 to 80 μm, and the thickness of the second layer 3
A suitable thickness is 2 to 10 μm. The thickness of the first layer 2 is
If it is thinner than 30 μm, the capacitance becomes large and the charging potential will not ride well, and if it is thicker than 80 μm, the residual potential will increase. In addition, if the thickness of the second layer 3 becomes thicker than 10 μm, the residual potential increases due to repetition.
If it is thinner than 2 μm, it will have little effect in preventing a decrease in charging potential. As the halogen, chlorine, iodine, fluorine, and bromine are used, and they mainly play the role of lowering the residual potential. The appropriate amount of halogen added is 2 to 1000 ppm; less than 2 ppm has no effect of lowering the residual potential, and more than 1000 ppm deteriorates electrical properties. (For example, increase in dark decay) In the present invention, the Te concentration in the second layer 3 does not necessarily have to be higher than the Te concentration in the first layer 2, and it is important that the second layer 3 does not contain halogen. be. The photoreceptor of the present invention can be manufactured by the following method. (1) Put Se-Te-halogen and Se-Te into two separate evaporation sources. First, the Se-Te-halogen evaporation source is heated to deposit the first layer.After the evaporation is completed,
The Se-Te evaporation source is heated to deposit the second layer on the first layer. (2) Put Se-Te and Se-halogen into two separate evaporation sources. The two evaporation sources are heated and deposited simultaneously, and the Se-halogen evaporation source is set so that the evaporation ends a predetermined amount of time earlier. This will be explained in detail below using examples. Example 1 Two stainless steel evaporation sources were prepared in a vacuum chamber, and the first evaporation source contained Se (88% by weight) - Te (12% by weight) - chlorine (100ppm) and the second evaporation source contained Se (88% by weight) - Te (12% by weight) - chlorine (100ppm). Se
(78% by weight)-Te (22% by weight) was added. then 5
First, the first evaporation source was heated to 300°C under a vacuum of ×10 ⁻⁵ mmHg to form a first layer having a thickness of 55 μm on an aluminum drum maintained at 70°C. Next, after the vapor deposition of the first evaporation source was completed, the second evaporation source was heated to 310° C. without breaking the vacuum to form a second layer having a thickness of 5 μm on the first layer, thereby obtaining a photoreceptor of the present invention. On the other hand, for comparison, only Se (88% by weight) - Te (12% by weight) - chlorine (100 ppm) was added to the evaporation source and 60 μm was deposited on an aluminum drum under the same evaporation conditions as before. These two photoreceptors were installed in a commercially available copying machine, the initial charging potential was set to 600 V, and the results were repeated. Table 2 shows the results. The two-layer structure photoreceptor of the present invention exhibited good characteristics with a low residual potential and almost no decrease in charging potential due to repetition.

[Table] Example 2 Two stainless steel evaporation sources were prepared in a vacuum chamber, and the first evaporation source contained Se (90% by weight) - Te (10% by weight),
Se-μm (300 ppm) was introduced into the second evaporation source.
The first and second evaporation sources are set in advance so that when deposited alone, the deposition speed and thickness shown in Table 3 can be obtained.

[Table] Electricity was applied to the first and second evaporation sources at the same time, and the first evaporation source was heated to 300°C and the second evaporation source to 280°C, and vapor deposition was performed for 21 minutes to obtain a 60 μm photosensitive layer on the aluminum drum. At this time, the surface of the aluminum drum is 70℃
was held in Since evaporation of the second evaporation source was completed at the time of 18 minutes, the photoreceptor obtained here is the photoreceptor of the present invention consisting only of Te--Te at a thickness of 6 μm from the surface. This photoreceptor was installed in a copying machine in the same manner as above, the initial charging potential was set to 600V, and the process was repeated. The results were almost the same as those of the photoreceptor of the present invention in Example 1, and the characteristics were good. As described above, according to the present invention, a photoreceptor having excellent charging potential stability and a very low residual potential can be obtained, so that the practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a photoreceptor according to the present invention. 1 is a conductive support, 2 is a first layer (Se-Te-
halogen layer), 3 is the second layer (Se-Te layer).

Claims (1)

[Claims] 1 A first layer made of selenium (Se), tellurium (Te) and halogen with a thickness of 20 μm to 80 μm and a second layer made of selenium (Se) and tellurium (Te) with a thickness of 2 μm to 10 μm on a conductive support. Electrophotography, characterized in that the tellurium concentration in the first layer is set to 3 to 14% by weight, the halogen additive is set to 2 to 1000 ppm, and the tellurium concentration in the second layer is set to 3 to 25% by weight. Photoreceptor.