JPS6255139B2 - - Google Patents

Description

[Detailed Description of the Invention] Glassy selenium, particularly so-called electrophotographic selenium having a composition in which tellurium (Te) is added to selenium (Se).
Although the SeTe photoreceptor is known as a stable photoreceptor with a wide spectral sensitivity range, it has disadvantages such as poor thermal stability, poor mechanical abrasion resistance, and short life.

Generally, an electrophotographic apparatus has a photoreceptor a (in the figure, it has a drum-like structure and is rotatably supported as shown by the arrow), which is the main part of an electrophotographic apparatus, as shown in the schematic diagram of FIG.
, a charger b for uniformly charging the photoconductor a, an optical exposure device c for forming a desired electrostatic latent image on the photoconductor, and a developing device d for developing the electrostatic latent image. , a transfer device e that transfers this onto a transfer material (for example, plain paper), a charger f for static elimination, a cleaning device g for removing developer material, etc., and the photoreceptor a passes through these various devices. The image is then subjected to charging, exposure, development, transfer, neutralization, and cleaning steps before being used for copying. The electrophotographic photoreceptor is
As the frequency of use increases due to the repetition of the above steps, the temperature inside the device increases, or the surface of the photoreceptor a wears out due to constant contact with various devices, and its electrical characteristics rapidly deteriorate. Therefore, the photoreceptor should have high sensitivity spectral characteristics without changing its characteristics under such harsh usage conditions, and should also have improved temperature hardness characteristics and mechanical strength such as abrasion resistance. High sensitivity and long life are required.

In view of the above, the present invention provides a highly sensitive and long-life electrophotographic photoreceptor that maintains stable electrical characteristics under harsh usage conditions, has improved spectral sensitivity, has excellent thermal stability, mechanical abrasion characteristics, etc. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail with reference to the drawings. FIG. 2 is a sectional view showing the structure of an electrophotographic photoreceptor according to an embodiment of the present invention. In the figure, 1 is a conductive substrate formed in the shape of an aluminum drum or an insulating substrate on which a metal coating is deposited. Use. 2 is an intermediate layer made of aluminum oxide or patent no.
Lead sulfide (Pbs) disclosed in No. 826801 (2-
1)+resin thin film (polycarbonate) (2-2), etc. are used. 3 is the first photoconductive layer, which is made by vacuum evaporation (vacuum degree
10 ^-5 to 10 ^-6 Torr, thickness 30 to 100μ).

4 is the second photoconductive layer, and a mixture of appropriate amounts of selenium (Se), tellurium (Te), antimony (Sb) and iodine (I) is placed in a quartz glass ampoule at 5×10 ^-5 Torr.
After evacuation, the mixture was sealed and reacted in a rotary furnace at 700° C. for 5 hours, then poured into deionized water, cooled, and pulverized to an appropriate particle size. This can be obtained by uniformly depositing this on the first photoconductive layer 3 by vacuum evaporation. It has been confirmed that the photoreceptor of the present invention having such a configuration has superior characteristics compared to conventional Se and Te photoreceptors.

This will be explained below using examples.

<Example> As shown in FIG. 2, an intermediate layer 2 such as a lead sulfide coating layer (2-1) and a polycarbonate coating layer (2-2) is formed on an aluminum substrate 1 in order to improve the adhesion with the photoconductive layer. After forming an alloy of selenium chloride and high purity selenium by reacting high purity selenium with 1 to 20 PPM of chlorine, this was vacuum deposited on the intermediate layer 2 to a thickness of 55μ and containing chlorine. A first photoconductive layer 3 having a ratio of about 4 PPM was formed. Next is selenium 84wt%, tellurium 15wt%, antimony 1wt%
% and 50 to 1000 PPM of iodine is then vacuum-deposited in a molybdenum boat without breaking the vacuum, and a second photoconductive material having a thickness of 10 μm and an iodine content of about 100 PPM is deposited on the first photoconductive layer 3. A conductive layer 4 was formed.

(At this time, the aluminum substrate temperature was 60°C, the degree of vacuum was 5 × 10 ^-5 Torr, and the boat temperature was 450°C.) Separately, for the purpose of comparing the characteristics, the first photoconductive layer 3 was made of pure selenium, 85wt% selenium for the second photoconductive layer 4
A photoreceptor having a composition of 15 wt % tellurium and a photoreceptor having a single layer of pure selenium without separating the first and second photoconductive layers were prepared in the same manner as described above.

FIG. 3 shows the results of measuring the spectral sensitivity of the above photoreceptor. In the figure, the vertical axis is the sensitivity, the horizontal axis is the optical wavelength, the curve A is the characteristic of the photoreceptor of the present invention, and the curves B and C are the conventional photoreceptor (B is Se+Se, Te layer structure,
C indicates the characteristics of Se structure).

The measurements were made by irradiating each photoreceptor with energy light such as monochromatic light and plotting the sensitivity at this time in the figure.
As is clear from the figure, the photoreceptor of the present invention exhibits extremely superior sensitivity at intermediate wavelengths (450 to 700 .mu.m) compared to conventional photoreceptors, particularly at wavelengths from 500 to 600 .mu.m.

Also, according to experiments, in the photoreceptor of the present invention, the first
In relation to the concentration of chlorine in the photoconductive layer and the concentration of iodine in the second photoconductive layer, chlorine (Cl) 1 to
It was confirmed that the sensitivity is extremely high for intermediate wavelengths in the range of 20 PPM and 50 to 1000 PPM of iodine. However, when the amount of chlorine exceeds 10 PPM, the drop in surface potential becomes large and performance deteriorates. FIG. 4 is a characteristic diagram showing the relationship between the concentration of antimony (Sb) in the second photoconductive layer and the change in the chlorine concentration (horizontal axis) and iodine concentration (vertical axis).

Figure 5 shows the repeated surface potential characteristics during operation of the photoreceptor of the present invention and the conventional Se and Te photoreceptors configured in a drum shape and installed in an electrophotographic apparatus. In the figure, the vertical axis is The surface potential, the horizontal axis shows charging and the number of repeated exposures, curve A shows the characteristics of the present invention, and curve B shows the characteristics of the present invention.
shows the conventional characteristics. In the experiment (see Figure 1), each photoreceptor was charged to a predetermined level (initial surface potential Vo) using a charger b, and then an optical exposure device c
Changes in surface potential were measured during intermediate exposure (image exposure) and full-surface exposure (measured with a surface electrometer near the arrow S in Figure 1) _.VI in the figure is after intermediate exposure. The surface potential of V _R indicates the surface potential (residual potential) after the entire surface is exposed.

That is, when comparing the photoconductor of the present invention and a conventional photoconductor, when the same potential is applied to both by charger b, the initial surface potential Vo (first time charging) is approximately 100 V lower than that of the conventional photoconductor. (because the charging efficiency decreases), but this value remains approximately constant even as the number of charging cycles increases. (Vo-A) On the other hand, the conventional type has a high initial surface potential, but shows a characteristic that it rapidly decreases between 1 and 10 repetitions, and then becomes almost constant. (Vo-B) The change in surface potential (V _I ) after intermediate exposure is almost the same as above.

The surface potential (i.e., residual potential) of the photoreceptor of the present invention after full-surface exposure shows an extremely low value compared to conventional ones, and also shows a constant value regardless of the increase in the number of charging and exposure repetitions (V _R − A).

In other words, with the photoreceptor of the present invention, images with high contrast and stable image quality can be consistently obtained regardless of the number of repetitions, whereas with conventional Se and Te photoreceptors, the number of repetitions is 1 to 10 (i.e., the number of copies). This shows that the image quality changes in the range of 1 to 10 images). This means that in the photoreceptor of the present invention, the second photoconductive layer 4, which undergoes photon conversion under the influence of chlorine (Cl) and iodine (I), and the first photoconductive layer 3, which retains and transfers charges, each have short lifetimes. It is thought that because a high-density trap is created, the photoreceptor quickly reaches saturation and becomes stable with a small amount of light.

Figure 6 shows the temperature surface of the photoconductor of the present invention and the conventional Se and Te photoconductors, respectively formed and mounted in the form of a drum in the same manner as above, and measuring the internal temperature during operation and the amount of wear on the surface of the photoconductor. This is a hardness (wear) characteristic diagram, in which the vertical axis shows the wear amount d (μ) and the horizontal axis shows the inside temperature °C (drum surface temperature). Curve A shows the characteristics of the present invention, and curve B shows the conventional characteristics. show.

In the experiment (see FIG. 1), a drum-shaped photoreceptor a was continuously rotated for 10 hours, and at the same time, the amount of surface abrasion d was measured when the surface of the photoreceptor was abraded by a cleaning device g (resin flocked brush).

As is clear from the figure, in contrast to conventional photoconductors, where the amount of wear increases rapidly when the internal temperature exceeds 25℃, the photoconductor of the present invention has excellent temperature hardness that hardly increases even around 50℃. Show characteristics.

This means that the amount of wear of the photoconductive layer is small, so there are few changes in electrical characteristics, and a long life is maintained.

That is, in the photoreceptor of the present invention, antimony (Sb), which has the property of particularly enhancing heat resistance, reacts thermally with iodine (I) in the second photoconductive layer 4, resulting in a vapor pressure lower than that of antimony alone. It is thought that the composition ratio of antimony in the second photoconductive layer can be adjusted with precision during manufacture, and the softening point (temperature) also increases with the increase in antimony, so that the abrasion strength at high temperatures becomes higher than at room temperature.

As is clear from the above explanation, the present invention has superior spectral sensitivity characteristics compared to conventional selenium and tellurium photoreceptors, and has particularly high sensitivity on the intermediate wavelength side, which increases the degree of freedom in selecting the exposure source. This has great practical effects because it can provide an electrophotographic photoreceptor with excellent heat resistance and abrasion resistance, high sensitivity, and long life.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an electrophotographic apparatus, FIG. 2 is a cross-sectional view showing the structure of a photoreceptor according to an embodiment of the present invention, and FIG. 3 is a spectral diagram showing the relationship between light wavelength and sensitivity of the present and conventional photoreceptors. Figure 4 is a sensitivity characteristic diagram showing the relationship between the chlorine concentration, iodine concentration and antimony concentration of the photoconductor of the present invention, and Figures 5 and 6 are repeated comparisons of the photoconductor of the present invention and the conventional photoconductor, respectively. They are a potential characteristic diagram and a temperature surface hardness characteristic diagram. In the figure, 1 is a conductive support, 2 is an intermediate layer,
3 is the first photoconductive layer, 4 is the second photoconductive layer, A is the characteristic curve of the photoreceptor of the present invention, and B and C are the characteristic curves of the conventional photoreceptor.

Claims (1)

[Claims] 1 A first photoconductive layer composed of selenium (Se) containing 1 to 10 PPM of chlorine (Cl), directly or via an intermediate layer, on a conductive substrate, and selenium (Se) and tellurium (Te). , antimony (Sb) and
An electrophotographic photoreceptor characterized in that a second photoconductive layer composed of 50 to 1000 PPM of iodine (I) is sequentially laminated.