JPS6146967A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent occurrence of interference fringes on images due to the interference between a reflected light from a conductive base body and a coherent light of the incident light for a long time by setting the roughness and the pitch of ruggedness of the surface of the conductive base body of a photosensitive body within prescribed values by etching. CONSTITUTION:The surface roughness and the pitch of projecting parts of the surface ruggedness of a conductive base body 20 of a photosensitive body 2 are set to 0.05-3.0mum and 0.2-10mum respectively, and a thin film layer 21 consisting of a layer 21A which stops electric charge injection from the base body 20, a layer 21B which receives a laser light to generate carriers, and a protective layer 21C is formed on the base body 20. In case of <=0.05mum roughness and >=0.2mum pitch, interference fringes occur on images because the incident light cannot be scattered sufficiently on the surface of the base body; and in case of >=3mum roughness, the adhesive strength between the base body and the thin film layer is degraded, and they are peeled partially to degrade the light attenuation characteristic of the surface potential. The roughness of the surface of the base body is set within prescribed values in this manner to prevent the occurrence of interference fringes when images are formed with the coherent light.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an electrophotographic photoreceptor that forms an image by irradiating an electrophotographic photoreceptor with coherent light having an emission wavelength of 600 rv or more to form a charge pattern on its surface. Concerning photographic equipment.

[Technical Background of the Invention and Problems Therein] As this type of electrophotographic apparatus, there is one that uses coherent light such as @e-Ne laser light or semiconductor laser light as a light source for exposure. Laser light has a characteristic that its wave packet does not spread easily, so it is possible to perform image exposure by scanning with a relatively simple optical system. Therefore, it is particularly suitable for application to devices that form images based on time-series electrical signals such as computer output. Moreover, such a device generates less noise and is capable of high-speed processing compared to conventional impact type printers and the like. For this reason, there is an increasing demand for electrophotographic apparatuses suitable for image exposure using coherent light.

Generally speaking, the shorter the wavelength of laser output, the larger the device. Among lasers that emit light in the visible range, the 1e-Ne laser beam has the longest wavelength (633 nm) and the device is smaller. When this is used as a light source, photoconductive materials that can be used in the electrophotographic photoreceptor are limited to alloys such as Se, Te, or AS, or amorphous silicon, microcrystalline silicon, or crystalline silicon.

Furthermore, recently attempts have been made to use semiconductor lasers to miniaturize devices, but in this case a photoconductive material with higher sensitivity at longer wavelengths is required.

Currently, the emission wavelength of a semiconductor laser is about 780 ng+, and there are few photoconductive materials that are sensitive to this laser light and can be used as electrophotographic photoreceptors, one of which is amorphous silicon.

This amorphous silicon does not necessarily have high sensitivity to light with a wavelength of 780 nl, and conventionally sensitization to long wavelengths was performed by mixing Ge, but
In order to absorb all the laser light having an intensity of o+2, sec, the thickness of the photoconductive layer must be 30 μm or more.

However, when the layer thickness of the photoconductive layer is 30 μm or more, the formed image becomes blurred due to the low mobility of photogenerated carriers in the amorphous silicon that forms the photoconductive layer. , there is a limit to the layer thickness of 30 μm or more. For this reason, when using a long wavelength light source such as a semiconductor laser beam, the light transmitted through the photoconductive layer is reflected on the surface of the conductive substrate, and this reflected light interferes with the incident light, resulting in interference fringes. There was a problem that the formed image became unclear.

In order to prevent such interference, measures such as coating a substance that absorbs long wavelength light between the conductive substrate and the photoconductive layer have been adopted; There were problems in terms of effects on the properties of amorphous silicon and adhesiveness.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is that when coherent light is used as a light source, interference between reflected light from a conductive substrate and incident light causes i. An object of the present invention is to provide an electrophotographic apparatus that can prevent the occurrence of stripes on formed images.

[Summary of the Invention] In order to achieve the above object, the present invention has a surface roughness of 0.
ill! containing a photoconductive material on the surface of a conductive substrate having a pitch of 0.05μIn or more and 3.0μI11 or less and a pitch between convex portions of the surface irregularities of 0.2μm or less! An electrophotographic photoreceptor formed of a layer, a charging means for charging the electrophotographic photoreceptor,
The charged electrophotographic photoreceptor has an emission wavelength of 60Or+n+
A light source that irradiates the above-mentioned coherent light to form a charge pattern on the surface thereof, a developing means that develops the charge pattern on the electrophotographic photoreceptor, and a recording medium for storing the developed image on the electrophotographic photoreceptor. The conductive substrate has a roughened surface, and the incident light is diffusely reflected on the roughened surface of the conductive substrate.

[Embodiment J of the invention Next, the present invention will be explained in detail.

FIG. 1 is a schematic sectional view showing an embodiment of an electrophotographic apparatus according to the present invention. This device has a semiconductor laser 1 as a light source that outputs coherent light with an emission wavelength of 780 nm. First, an electrophotographic photoreceptor 2 is provided in the center of the apparatus so as to be rotatable in the direction of the arrow, and a charger 3 serving as a charging means for uniformly charging the surface of the electrophotographic photoreceptor 2 is arranged above it. ing. The surface of the electrophotographic photoreceptor 2 charged by the charger 3 is subjected to image exposure via the semiconductor laser 1, and for this purpose, the laser light from the semiconductor laser 1 is reflected toward the electrophotographic photoreceptor 2. A polygon mirror 4 and a lens 5 that focuses the laser beam reflected by the polygon mirror 4 onto the surface of the electrophotographic photoreceptor are provided. The surface potential of the electrophotographic photoreceptor in the portion irradiated with the laser light is optically attenuated, and a charge pattern is formed there.

A developing device 7 serving as a developing means for attaching a developer to the charge pattern and developing it is disposed at the forward end of the electrophotographic photoreceptor 2 along the rotational direction. On the other hand, this developer 7
A paper feed cassette 9 containing a recording medium such as paper 8 is provided at a lower position, and the uppermost layer of paper 8 can be taken out via a paper feed roller 10. The taken out paper 8 is aligned by the registration rollers 11, and is transported forward in time with the rotation of the electrophotographic photoreceptor 2 in the six directions of arrows. When the paper 8 has been conveyed to a position where it contacts the surface of the electrophotographic photoreceptor 2, the developed image has been conveyed to a position opposite to the paper 8 by the rotation of the electrophotographic photoreceptor 2, and the developed image - The developer forming the image is transferred onto the paper 8 via a transfer device 12 as a transfer means. In order to fix the transferred developer onto the sheet of paper 8, a fixing roller 13 having a built-in heater is provided on one roller, and the sheet of paper 8 after fixing.
A paper discharge tray 14 for receiving and picking up the paper is arranged ahead of it. A cleaner 15 is provided to remove and clean the developer remaining on the surface of the electrophotographic photoreceptor 2 after transfer, and to remove static electricity from the roughly cleaned surface of the electrophotographic photoreceptor 2, the entire surface of the electrophotographic photoreceptor 2 is cleaned. A static elimination lamp 16 such as a tungsten lamp is provided for exposing.

Next, the electrophotographic photoreceptor 2 will be explained in detail.

FIG. 2 is a sectional view showing the laminated structure of the electrophotographic photoreceptor. The present electrophotographic photoreceptor 2 includes a thin film layer 21 containing a photoconductive material f31 formed on the surface of a conductive substrate 20 such as an aluminum drum. The surface of the conductive substrate 20 is roughened so that the surface roughness is 0.05 μm or more and 3.0 μm or less, and the pitch between the convex portions of the surface irregularities is 0.2 μm or less. Such surface roughening treatment can be performed by etching with an alkaline solution such as potassium hydroxide or sodium hydroxide, sandblasting, or puff polishing. Especially naughty.

In the case of etching, the concentration and temperature of the etching solution.

The roughness can be adjusted by changing the etching time, and the surface can be evenly roughened. The thin film layer 21 has a blocking layer Ji12 that prevents charge injection from the conductive substrate 20.
1A, a photoconductive material 1121 made of a photoconductive material that generates carriers upon receiving laser light from the semiconductor laser 1;
B and a surface layer 21C for retaining and protecting the surface of the photoconductive layer 21B are successively laminated. This i'i9 film layer 21 can be formed by sputtering or glow electrolysis. For example, in the case of constructing amorphous silicon, which is a non-crystalline material using Si atoms as a matrix, by the glow discharge decomposition method, first, a thoroughly cleaned conductive substrate 20, for example, an aluminum drum, is placed in a reaction vessel, and the interior of the reaction vessel is At the same time, the temperature of the aluminum drum was raised to about 300℃ while exhausting until the temperature was below 1xio-3torr.
℃, and once the inside of the reaction vessel has been sufficiently evacuated and the temperature of the aluminum drum has stabilized, the inside of the reaction vessel is brought to about 0.1 to 10 tOrr via another exhaust system, and then the mass flow controller is pumped through the gas pipe. 5iHa gas (raw material gas)
, B21-I6 gas (doping gas) and O2 gas (
A film can be formed by introducing a gas such as a gas for adding impurities into a predetermined port and decomposing the gas by glow discharge. In particular, the M film layer 21
When the thin film layer 21 is formed by glow discharge decomposition of 5iHa gas, the thin film layer 21 is made of amorphous silicon which has excellent adhesion to the irregularities on the surface of the conductive substrate 20 and is highly sensitive to laser light with an emission wavelength of 780 nm. Therefore, a small semiconductor laser can be used as a light source, making it possible to miniaturize the device and perform high-speed image formation.

Note that the structure of the thin film layer is not limited to the laminated structure explained in FIG. 2, but it is sufficient that at least a photoconductive layer made of a photoconductive material is formed. Further, the photoconductive material is not limited to amorphous silicon, but may also be a material sensitive to coherent light having an emission wavelength of 600 nm or more, such as an alloy of Se, Te, or As.

Next, an electrophotographic photoreceptor 2 having the basic structure as described above is prepared.
We will explain the experimental results using . For example, as shown in Fig. 3, the surface roughness measured using a stylus surface roughness meter (for example, JIS maximum height) is about 0.8 μm, and the pitch between convex parts is about 0.1 μm. When an electrophotographic photoreceptor 2 comprising a thin I1w layer 21 made of amorphous silicon formed on a transparent substrate 20 is used in the apparatus shown in FIG. When formed, interference fringes are only slightly visible on the formed image, while on the other hand, when a bias is applied to such an extent that fog due to development disappears, no interference fringes appear on the formed image.

Experiments were conducted using various electrophotographic photoreceptors 2 in which the surface roughness of the conductive substrate 20 and the pitch between the convex parts were changed. When the thickness was 0.2 μm or more, interference fringes were generated on the formed image. This is considered to be because the incident light cannot be sufficiently scattered on the surface of the conductive substrate 20 within the above range. In addition, when the surface roughness is 3μ or more, it cannot withstand repeated use, and the thin film layer 21
was partially peeled off, and the light attenuation characteristics of the surface potential were partially degraded. This is considered to be due to the fact that the adhesiveness and adhesion between the conductive substrate 20 and the thin film layer 21 deteriorate in the above range.

Therefore, the apparatus of this embodiment includes an electrophotographic photoreceptor 2 using a conductive substrate 20 with a surface roughness of 0.05 μm or more and 3.0 μm or less and a pitch between convex portions of the surface irregularities of 0.2 μm or less. The generation of stripes on a formed image due to interference between light reflected from the conductive substrate 20 and incident light can also be prevented by repeated image formation over a long period of use.

[Effects of the Invention] As is clear from the above detailed description, when coherent light is used as a light source, the electrophotographic apparatus of the present invention produces images that are formed due to interference between reflected light from a conductive substrate and incident light. It is possible to prevent the occurrence of upper stripes.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an electrophotographic apparatus according to the present invention, FIG. 2 is a cross-sectional view showing the laminated structure of an electrophotographic photoreceptor, and FIG. FIG. 3 is an explanatory diagram showing the measurement results of the surface roughness of the conductive substrate measured by the method. 1...Light source, 2...Electrophotographic photoreceptor, 3...Charging means, 7...
・Developing means, 8...Recording medium, 12...
... Transfer means, 20 ... Conductive substrate, 2
1... Thin film layer.

Claims (3)

[Claims] (1) A thin film layer containing a photoconductive material is formed on the surface of a conductive substrate having a surface roughness of 0.05 μm or more and 3.0 μm or less and a pitch between convex portions of the surface irregularities of 0.2 μm or less. an electrophotographic photoreceptor, a charging means for charging the electrophotographic photoreceptor, and an electrophotographic photoreceptor having an emission wavelength of 60 nm.
A light source that irradiates coherent light of 0 nm or more to form a charge pattern on the surface of the light source, a developing means that develops the charge pattern on the electrophotographic photoreceptor, and records a developed image on the electrophotographic photoreceptor. An electrophotographic apparatus comprising a transfer means for transferring onto a medium. (2) The electrophotographic apparatus according to claim 1, wherein the conductive substrate has irregularities formed on its surface by etching with an alkaline solution. (3) The electrophotographic apparatus according to claim 1, wherein the thin film layer is made of an amorphous material or a microcrystalline material containing Si atoms as a matrix.