JPS60252355A - Electrophotographic sensitive selenium and selenium photosensitive film and its manufacture - Google Patents

Abstract

PURPOSE:To reduce traps of electrons and positive holes due to defects of the structure of an Se photosensitive film and to simultaneously lower residual potential at the time of positive or negative charging by incorporating a minute amt. of Mg. CONSTITUTION:Se is doped with a minute amt. of Mg by melting a mixture of an Mg source, such as a simple substance of Mg, MgSe, or other Mg compds., and Se in a tightly closed vessel and homogenizing them, or melting Se in the vapor of the simple Mg substance or a volatile Mg compds., or the mixture of them or the like. Said photosensitive film of Mg-doped Se is formed on a substrate by the vapor deposition, sputtering, ion plating, etc., using said Mg.Se source. In the photosensitive film thus obtained, dangling bonds in an amorphous Se are compensated by the addition of Mg, and density of structural defects themselves is lowered. As a result, the number of the traps of electrons or positive holes can be decreased and the absolute value of residual potential both in the case of positively or negatively charging can be lowered at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a selenium photosensitive film for electrophotography, selenium added with a trace component used therein, and a method for producing the same.

Selenium is used as an electrophotographic photoreceptor due to its photoconductive properties.

A selenium-deposited film is used as an electrophotographic photoreceptor.

The so-called Xerox method consists of the following steps: (a) Charging: Using corona discharge in the air, the surface of a photosensitive plate having a selenium vapor deposited film on the substrate is positively charged.

(b) Exposure (printing): Next, while the charged photosensitive plate is kept in a dark place (preparing for printing), its surface potential gradually decreases (
(This is called dark decay), but when the original image is irradiated with light to print it, the charge in the exposed area disappears, creating a latent image with the same charge as the original image. (c) Development; Next, the above photosensitive plate By sprinkling the surface of the toner with a mixed powder of toner made of fine carbon powder coated with resin and small glass spheres called a carrier, the toner adheres to the latent image area of the charge and a visible image is obtained.

(a) Transfer: When a suitable paper is placed on the surface of the photosensitive plate after development and corona discharge is performed again on the surface, the toner on the photosensitive plate is absorbed and adhered to the paper.

(e) Fixing: After the transfer is completed, the paper is peeled off and heated with an infrared heater to fuse the toner resin to the paper.

By carrying out each of the above steps, a copy image (electronic photograph) of the original image can be obtained.1 However, in the case of a photosensitive plate using a normal selenium vapor-deposited film, the light is irradiated during the exposure (baking) step in (b). The surface potential of the part may not be completely reduced to zero and some potential may remain.

(This is called a residual potential.) When this residual potential occurs, the contrast of the resulting electrophotograph becomes unclear. A so-called ghost phenomenon occurs.

BACKGROUND ART A method of doping a halogen element into a selenium-deposited film in order to reduce the residual potential is known, but this method has the disadvantage of increasing dark decay.

Generally, high-purity selenium (4N to 5N) is used in photoconductors for copying machines.
is used. However, even if such high-purity selenium is used, or even if a photoresist film is made using even more highly purified selenium, electrons and holes will be generated due to structural defects in selenium, as will be described later in the section 1. A certain amount of traps remain8 Because of this trap, in photoresist films made using high-purity selenium, residual potentials of approximately the same size, although not large, remained in both positive and negative charges. .

The present inventors previously invented a method for reducing hole traps by containing a certain amount of oxygen in a high-purity selenium photosensitive film (Japanese Patent Application No. 58-1703-2099).
79) 8 However, this method had the disadvantage of increasing electron traps.

Problems to be Solved by the Invention In the end, a method for simultaneously reducing both the residual potentials of a high-purity selenium photoresist film during positive and negative charging has not been studied in the technology. This is because the conventionally used pure selenium (4N to 5N) contains various impurities.

This is because impurity traps and the like coexist in addition to traps due to structural defects, making it difficult to conduct research on controlling the characteristics of selenium photoresist films.

An object of the present invention is to obtain a selenium photosensitive film that reduces trapping of electrons and holes due to structural defects and simultaneously reduces residual potential during positive and negative charging. As can be seen from the description of the prior art, there has been no invention suggesting a means for solving such problems, and addition of elements to selenium as a solution to such problems has not been proposed.

The present inventors have conducted various studies using high-purity selenium with the aim of reducing the trapping of electrons and holes due to structural defects and simultaneously reducing the residual potential during positive and negative charging of selenium photosensitive films. As a result of repeated efforts, it was discovered that when a trace amount of magnesium is contained in a high-purity selenium photosensitive film, the residual potential during positive and negative charging can be reduced at the same time, leading to the present invention.

That is, the present invention is a selenium photosensitive film characterized by containing a trace amount of magnesium, a magnesium-doped selenium film therefor, and a method for producing the same.
Magnesium-doped selenium for a photoreceptor for producing a selenium photosensitive film is one or two selected from magnesium alone, magnesium selenide, and other magnesium compounds.
A mixture of a magnesium source and selenium consisting of more than one species can be melted and homogenized in a vacuum ampoule or other closed container, or the selenium can be melted in a vapor of pure magnesium, a vapor of a volatile magnesium compound, or a mixture of these vapors. Manufactured by The amount of magnesium added to the photoreceptor selenium is 1 to 50,000 ppm.
w is desirable.

A selenium photosensitive film containing a trace amount of magnesium, that is, a magnesium-doped selenium photosensitive film, can be produced by resistive heating vapor deposition, electron beam vapor deposition, or sputtering on a substrate using the above-mentioned magnesium-doped selenium, or by using magnesium alone, magnesium selenide, or other magnesium. Either one or more magnesium sources selected from compounds and selenium are separately melted and simultaneously vapor-deposited or sputtered in parallel, or a mixture of the magnesium source and selenium is vapor-deposited or sputtered.

Alternatively, it can be produced by resistive heating evaporation, electron beam evaporation, or ion blating of selenium in the vapor of magnesium alone, the vapor of a volatile magnesium compound, or a mixture of these vapors.

Magnesium content in selenium photosensitive film is 01 to 100
0 ppmw is desirable.

2. The present invention relates to a selenite alloy for photoreceptors.

It is also applicable to selenium arsenic alloy, selenium antimony alloy or selenium bismuth alloy.

Function The selenium commonly used for photoconductors is 4N to 5N pure selenium, and selenium photosensitive films made from such selenium contain traps caused by impurities in addition to traps caused by structural defects. On the other hand, photoresist films using high-purity selenium of 5N5 to 6N have good and stable properties, but they still have some residual potential during positive and negative charging. is an electron originating from a structural defect.

As mentioned above, this is because hole traps remain.

The reason why a residual potential remains even in a high-purity selenium photoresist film is considered to be as follows. Since selenium is amorphous,
There are many dangling bonds (Do). Since this dangling bond is thermally stable when partially polarized, it is polarized according to the ninth order equation.

D0ヰD++ D- D+ and D- are positively and negatively charged dangling bonds, respectively, and act as traps for electrons and holes, respectively. Neutral condition CD for high purity selenium containing no impurities
+3=CD-], D+ and D- become almost the same number. The residual potential of a high-purity selenium photoresist film is due to such structural defects I.
) +, electrons due to D-.

This is thought to be due to space charges created when carriers are trapped in hole traps. Therefore.

No matter how highly purified selenium is, the residual potential due to this structural defect cannot be reduced below a certain value as long as dangling bonds exist.

If according to the invention magnesium is added.

Compensates for dangling bonds in amorphous selenium.

By reducing the structural defect density itself, electrons,
This reduces hole trapping and lowers the residual potential.

Example A mixture of high-purity selenium with a predetermined amount of magnesium as shown in Table 1 was subjected to resistance heating vacuum evaporation on a mirror-finished aluminum substrate to a thickness of K 50 μm. The vapor deposition conditions are as follows.

Evaporation source temperature 270°C Substrate temperature 60°C Vacuum degree 2. x 10 Torr deposition time 60
The electrophotographic characteristics of the magnesium-doped selenium photoresist film sample prepared as described above were measured. The measurement conditions are as follows.

Corona discharge voltage 5KV Dark decay time 2 sec Light decay time 30 sec Static neutralization light illuminance 20000 lux Static neutralization time 2 days θC Number of repeated measurements 50 or more measurement experiments revealed the amount of magnesium added to high-purity selenium for photoreceptors and the residual potential. The results are shown in Table 2.

Table 2 Residual Potential By adding magnesium, electrons and holes can be simultaneously reduced.2 As seen from Table 2, it was possible to further reduce both the residual potential of the selenium photosensitive film during positive and negative charging.

Patent applicant: Japan Mining Co., Ltd. Agent: Patent attorney (7569) Keishi Namikawa

Claims (1)

[Claims] (i) Selenium for electrophotographic photoreceptors characterized by containing a trace amount of magnesium. (2) One or two selected from selenium and magnesium alone, magnesium selenide, and other magnesium compounds. A method for producing magnesium-doped selenium for electrophotographic photoreceptors, which comprises melting and homogenizing a mixture of the above magnesium sources in a vacuum ampoule or a closed container. (3) Vapor of simple magnesium, volatile magnesium A method for producing magnesium-doped selenium for electrophotographic photoreceptors, which is characterized by melting selenium in a vapor of a compound or a mixed vapor of simple magnesium and a volatile magnesium compound. Selenium photosensitive film for electrophotography, (5) A method for producing a magnesium-doped selenium photosensitive film for electrophotography, characterized by vapor-depositing or sputtering selenium containing a trace amount of magnesium, that is, magnesium-doped selenium; (6) Magnesium alone, selenium Magnesium. Co-evaporation or co-sputtering of separately melted selenium and one or more magnesium sources selected from other magnesium compounds, or vapor-deposition or sputtering of a mixture of the magnesium source and selenium. Production of a magnesium-doped selenium photosensitive film for electrophotography, which is characterized by: (7) Vapor deposition of selenium in a vapor of simple magnesium, a vapor of a volatile magnesium compound, or a mixed vapor of simple magnesium and a volatile magnesium compound. Alternatively, a method for producing a magnesium-doped selenium photosensitive film for electrophotography, which comprises ion plating.