JPS62273593A - Electrophotographic copying method - Google Patents

Abstract

PURPOSE:To improve the mechanical strength, durability, photosensitivity, general purpose color property, and long-wavelength sensitivity, by providing a process electrifying a photosensitive body in the polarity which is opposite to the polarity of the charging performed to the body thereafter and can remove remaining electric charges on the surface of the body during the period from the cleaning to the electrifying of the photosensitive body. CONSTITUTION:By providing the 2nd electrifier 2' between the 1st electrifier 2 and uniform exposing section 9, the surface of a photosensitive body 1 is electrified in the positive polarity by means of the 1st electrifier 2 after the body 1 is electrified in the negative polarity and surface electric charges remaining on the surface of the photosensitive body 1 are removed. It is desirable to use a material that shows a charge injecting prohibiting property against the secondary charging and a charge-injection inhibiting property against the primary charging for making the photosensitive body 1. Moreover, the degree of the secondary electrical charging is set to a degree at which the remaining electric changes are removed and, when light irradiation is also used, to a degree at which the electric charges which cannot be removed by the light irradiation only can be removed. Therefore, the mechanical strength, durability, photosensitivity, general purpose color property, long-wavelength sensitivity, etc., of this copying machine become excellent and excellent pictures can be obtained stably.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic copying method, and more specifically, a photoconductive layer mainly composed of amorphous silicon on a support. The present invention relates to an electrophotographic copying method using the formed electrophotographic photoreceptor.

For example, selenium (Se),
Photoreceptors using inorganic photoconductive materials such as cadmium sulfide (CdS) and zinc oxide (ZnO), polyJ-N-vinylcarbazole (PVK), and trinitrofluorenone (T
Photoreceptors using organic photoconductive materials such as NF) are commonly used. Selenium-based photoreceptors have the advantage of high sensitivity and long life, and sensitization or durability can be easily improved by alloying. However, problems remain in terms of mechanical strength and heat resistance. Photoreceptors using zinc oxide generally have the disadvantages of low sensitivity and short life. A photoreceptor using cadmium sulfide is usually provided with a relatively transparent insulating layer on its uppermost surface, and when used, it can be used for two-order charging, one reverse polarity secondary charging, image sensitization, or one-order charging and one-order charging. It requires a complicated latent image forming process called the so-called NP method, which includes reverse polarity secondary charging, simultaneous image exposure and uniform exposure. Furthermore, photoreceptors using organic photoconductive materials are
Generally, they have a short lifespan, and the sensitivity of the organic semiconductor itself is relatively low. As mentioned above, each of the electrophotographic photoreceptors used conventionally has problems that need to be solved, and there are still photoreceptors that have sufficient characteristics such as high durability, high heat resistance, and high light sensitivity. The reality is that this has not been achieved.

From this point of view, recently, photoreceptors that do not have the above-mentioned drawbacks, that is, have excellent mechanical strength such as surface hardness and abrasion resistance, have high heat resistance, long life, and high light sensitivity, and have a wide range of colors. As a new photoreceptor with excellent properties, an amorphous silicon photoreceptor that uses amorphous silicon (a.k.a. amorphous silicon or amorphous 5il-icon) as its main component is attracting attention as a photoconductive material. The amorphous silicon film used is, for example, plasma CVD method (P
lasma Chemical Vapor Decom
It is formed by glow discharge decomposition of silane (SiH,) gas using the position method. In this case, hydrogen atoms generated by the decomposition of the raw material silane gas are automatically incorporated into the amorphous silicon film, and the hydrogen-containing amorphous silicon film obtained in this way does not contain hydrogen. It has a high dark resistance compared to other materials, and at the same time has high photoconductivity. In addition, the spectral sensitivity range is wide, approximately 380 nm to 700 nm.
It has panchromatic properties up to 100%, has high photosensitivity, and can provide good photosensitivity even in the infrared region with longer wavelengths.

For the above reasons, amorphous silicon photoreceptors have low mechanical strength and
It can be said that it is an electrophotographic photoreceptor with ideal characteristics, such as excellent durability, photosensitivity, panchromaticity, and long wavelength sensitivity.

[Problem that the invention seeks to solve]

However, the amorphous silicon photoreceptor described above has the following practical drawbacks. That is, electrophotographic photoreceptors mainly composed of amorphous silicon have a problem in that they have a high residual potential and cannot withstand practical use. In Japanese Patent Application Laid-open No. 56-39548,
In order to solve this problem of residual potential, a method of using an electrophotographic photosensitive plate is developed in which the residual charge on the photosensitive plate is removed by irradiating the photosensitive plate with light after the photosensitive plate is exposed to light and before being charged again. Proposed. However, according to research conducted by the present inventors, even with such light irradiation, the charge remaining on the amorphous silicon photoreceptor cannot be completely removed, and the exposure and development process must be repeated to actually remove the cypress. It was discovered that over time, the outlines of letters and pictures became less sharp, that is, the image quality became blurry. This is thought to be because charges are trapped on the surface of the amorphous silicon photoreceptor for some reason. These drawbacks are a fatal problem in that electrophotographic photoreceptors mainly made of amorphous silicon cannot withstand actual use, even though they have the ideal characteristics mentioned above. becomes.

The object of the present invention is to provide an electrophotographic photoreceptor mainly made of amorphous silicon, which has mechanical strength, durability, photosensitivity, panchromaticity,
This solves the above-mentioned problems and allows stable image quality to be achieved without impairing excellent characteristics such as long-wavelength sensitivity due to material changes, or without going through the complicated latent image formation process as in the NP method. The object of the present invention is to provide an electronic photocopying method that can be used in a variety of ways.

[Means for solving problems]

The present invention uses an electrophotographic photoreceptor whose photoconductive layer is mainly made of amorphous silicon, and reverses the primary charging after cleaning in an electrophotographic process including secondary charging, exposure, development, transfer, and cleaning. This electrophotographic method includes a step of performing secondary charging to remove residual surface charges. The photoconductor used here may be provided with a charge injection blocking layer at the interface between the substrate and the photoconductor, but a layer that exhibits charge injection properties against secondary charging and charge injection blocking properties against primary charging is recommended. preferable.

Note that the degree of secondary charging is set to a level that removes residual charges. In addition, when using light irradiation in combination, the charge that cannot be removed by light irradiation is removed.

be made to have a degree of strength.

〔Example〕

Examples of the present invention will be described below in comparison with conventional methods.

First, a method for manufacturing a photoreceptor mainly made of amorphous silicon will be briefly described. A cylindrical A42 substrate is connected to a capacitively coupled bladder 7 CV D (Chemical Vapor
The substrate temperature was maintained at 230°C, and 100% silane (SiH,) gas was pumped into the reaction chamber at a rate of 100 cc per minute, and 1100 pp diborane (B2H6) gas diluted with hydrogen. 25cc/min, and 100% hydrogen (H2) gas at 1/min.
Inflow in the range of 15 cc, and the inside of the reaction tank is 0.5 Torr.
After maintaining the internal pressure at , an RF current of L 3.56 M)Iz was applied to generate a glow discharge, and the output of the RF power source was maintained at 80 WI.

A photoconductor made mainly of amorphous silicon produced under these conditions has high surface hardness, excellent wear resistance and heat resistance, high dark resistance and high light sensitivity, and has excellent electrophotographic photoconductor properties. It was excellent.

Comparative Example> The photoreceptor thus obtained was installed in a copying machine having the configuration shown in FIG. 2, and an image was printed.

This copying machine has a photoreceptor l mainly made of amorphous silicon, and around it a first charger 2, an image exposure optical system 3, a developer 4, a transfer charger 6, a peeling charger 7, a cleaning blade 8, and a uniform The exposure devices 9 are arranged clockwise in this order. The photoreceptor 1 is rotated clockwise, and in this comparative example, the photoreceptor 1 is rotated clockwise.
The process of charging (positive charging) - image exposure - development (-component development) -> transfer - clearing - uniform exposure was performed to create an image.

The first image at this time was relatively good, but the outlines of the characters and pictures in the second and subsequent images were not sharp, that is, the images were quite blurry.

When this photoreceptor was allowed to rest for a sufficient period of time without doing anything, and then the image was printed again, the first image was still relatively good, but the second and subsequent images were blurred. Table 1 shows the degree of blurring in terms of resolution.

In this comparative example, a corotron charging device was used as the charger, and charging was performed at a corona voltage of 7 KV.

Comparative Example 2 Images were printed in the same manner as in Comparative Example 1, except that the polarity of the charge was reversed, that is, it was negatively charged. The current applied to the developing device (,!
The DC component of the voltage and the polarity of the transfer power cutter were also set to appropriate polarities opposite to those of Comparative Example 1.

In this comparative example as well, a relatively good image was obtained for the first image, but images from the second and subsequent images were blurred.

The corona voltage for charging in this comparative example was 18 KV.

<Example 1> - The same photoreceptor as that used in Comparative Example 1 was used in a copying machine having the configuration shown in FIG. 1, that is, in the apparatus shown in FIG. During the second charger 2'
After applying a negative charge using the second charger 2', a positive charge was applied using the first charger 2, and otherwise an image was printed in the same manner as in Comparative Example 1. We were able to obtain stable image quality. Table 1 shows the resolution at this time.

In this example, corotron charging devices were used for both the first charger 2 and the second charger 2', and charging was performed at corona voltages of 7 KV and -5.3 KV, respectively.

<Example 2> Using the same photoreceptor and copying machine as in Example 1, the charging polarity was reversed.
That is, after applying a positive charge by the second charger 2', the first charger 2'
Negative charging was applied by the charger 2, and the cypress removal was performed with the DC component of the developing voltage applied to the developing device and the transfer charger set to appropriate values with polarities opposite to those in Example 1. As a result, it was also possible to stably obtain good image quality.

The resolution at this time is also shown in Table 1.

In this embodiment, the first charger 2 and the second charger 2
The corona voltages applied to ' are -8KV and +6K, respectively.
It was V.

(Table 1) Image sharpness (solution 1 image power) [Effects of the invention] According to the present invention, mechanical strength, durability, photosensitivity panchromaticity,
Although the amorphous silicon photoreceptor has ideal characteristics such as excellent long-wavelength sensitivity, it is possible to eliminate problems with its image quality, that is, blurred images, without losing its characteristics or going through complicated processes. This problem can be solved and good image quality can be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for implementing the electrophotographic copying method of the present invention, and FIG. 2 is a schematic diagram of an apparatus for implementing the conventional electrophotographic copying method. DESCRIPTION OF SYMBOLS 1... Photoreceptor mainly made of amorphous material, 2... First charger, 2'... Second charger, 3... Image exposure, 4...
Developing device, 5... Transfer substrate, 6... Transfer charger, 7.
... Peeling charger, 8... Cleaning blade, 9.
・Uniform exposure device. 2 First charger 2' Second charge gain 3 Shinjiko Koei system 4 Developing device 5 Transfer substrate 6 Transfer charger 9-a exposure plate

Claims (1)

[Claims] In an electrophotographic process including charging, exposure, development, transfer, and cleaning steps using an electrophotographic photoreceptor whose photoconductive layer is mainly made of amorphous silicon, the charging and the electrostatic charge are An electrophotographic copying method including a step of charging with opposite polarity to remove residual surface charge.