Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-06-03
2001-05-08
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S085000, C430S095000
Reexamination Certificate
active
06228545
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photoconductor. More specifically, the present invention relates to an electrophotographic photoconductor for use in a laser printer or a plain paper copier. Even more specifically, the present invention relates to an electrophotographic selenium photoconductor (more simply referred to as a “photoconductor”) comprising a photosensitive film formed by vacuum-depositing a selenium-arsenic alloy onto a conductive substrate.
Selenium photoconductors, often used as electrophotographic photoconductors, are manufactured by vacuum-depositing a selenium film onto an outer surface of a conductive substrate of an aluminum alloy. In, for example, laser printers or plain paper copiers, the outer surface of the conductive substrate is cylindrical in shape. Selenium-arsenic photoconductors, also formed by vacuum-depositing a selenium-arsenic alloy onto a conductive substrate, are used predominantly as a single-layered photosensitive film.
When mounted in, for example, a large-scale, high-speed printer capable of printing about 40 to 150 A-4-sized sheets per minute, a conventional single-layered selenium-arsenic photoconductor provides sufficient photo response. However, with printers capable of printing 300 or more sheets per minute, the single-layered film structure provides insufficient photo response due to small light exposure impinging on the surface of the photoconductor. This insufficient exposure deteriorates image quality when printing at such high speeds.
In addition, due to large variations in sensitivity depending on the wavelength of the light source, the single-layered selenium photoconductor does not enable free selection of the wavelength of the light source for a printer using the single-layered selenium photoconductor. Therefore, the conventional photoconductor-mounting machine is usually responsible for reducing the variation of the wavelength of the light source.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrophotographic selenium photoconductor which overcomes the foregoing problems.
It is a further object of the present invention to provide an electrophotographic selenium photoconductor which provides sufficient photo response despite the small light exposure impinging on the surface of the photoconductor.
It is another object of the present invention to provide an electrophotographic selenium photoconductor which enables a light source available for a photoconductor-mounting machine to be selected from a larger number of candidates to maintain more constant sensitivity despite variations of the wavelength of the light source.
Briefly stated, the present invention provides a selenium photoconductor having a charge transport layer and a charge generation layer formed on a conductive substrate. Both the charge generation layer and the charge transport layer are made from a selenium-arsenic alloy, with the charge generation layer having a concentration of arsenic greater than the concentration of arsenic in the charge transport layer. This concentration distribution results in a photoconductor having excellent charge-generation efficiency and mobility. In an alternate embodiment, a halogen is doped into the charge generation layer and charge transport layer. The resulting photoconductor is useful in large-scale, high speed printing operations.
According to an embodiment of the present invention, there is provided an electrophotographic selenium photoconductor comprising: a conductive substrate; a charge transport layer on the conductive substrate; a charge generation layer on the charge transport layer; the charge generation layer having a first arsenic concentration; the charge transport layer having a second arsenic concentration the charge generation layer and the charge transport layer are formed by vacuum-deposition of a selenium-arsenic alloy; the first arsenic concentration being greater than the second arsenic concentration; the first arsenic concentration is between about 30 and 50 weight percent; and the second arsenic concentration is between about 20 and 40 weight percent.
According to a further embodiment of the present invention, there is provided a photosensitive film for electrophotographic, comprising: a charge transport layer; a charge generation layer on the charge transport layer; the charge generation layer having a first arsenic concentration; the charge transport layer having a second arsenic concentration; the charge generation layer and the charge transport layer are formed by vacuum-deposition of a selenium-arsenic alloy; the first arsenic concentration is between about 30 and 50 weight percent; the second arsenic concentration is between about 20 and 40 weight percent; and the first arsenic concentration being greater than the second arsenic concentration, whereby a photo response is generated upon light impinging on a surface of the photosensitive film.
To achieve the above objectives, there is provided a selenium photoconductor comprising two types of vacuum-deposited selenium-arsenic alloy layers having different arsenic concentrations. The first type functioning in charge-generation. The second type functioning in charge-transportation. The inventors have found the configuration and conditions for both selenium-arsenic alloy layers to improve charge-generation efficiency and mobility of the photosensitive film.
The present invention relates to a electrophotographic selenium photoconductor comprising a conductive substrate and a photosensitive film on the conductive substrate. The photosensitive film includes a charge generation layer and a charge transport layer made by vacuum-depositing two types of selenium-arsenic alloys having different arsenic concentrations. The charge generation layer is formed from a selenium-arsenic alloy having a higher arsenic concentration. The charge transport layer is formed from a selenium-arsenic alloy with a lower arsenic concentration.
This configuration endows the electrophotographic selenium photoconductor with a greatly enhanced sensitivity. The increased sensitivity of the electrophotographic selenium photoconductor allows for the generation of an adequate photo response during large-scale and high-speed printing. Moreover, the enhanced sensitivity of the selenium photoconductor remains constant with varying light source wavelengths.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
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Fujii Makoto
Kina Hideki
Fuji Electric & Co., Ltd.
Goodrow John
Morrison Law Firm
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