Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-08-24
2001-08-07
Chapman, Mark (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S059400, C430S078000
Reexamination Certificate
active
06270936
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member having a photosensitive layer containing a specific compound as a charge-generating material. This invention also relates to a process cartridge and an electrophotographic apparatus which have such electrophotographic photosensitive member.
2. Related Background Art
Phthalocyanine pigments are not only used for coloring, but also have long attracted notice and have been studied as electronic materials used in electrophotographic photosensitive members, solar cells, sensors and so forth.
In recent years, printers to which electrophotography is applied are also in wide use as terminal unit printers. These are chiefly laser beam printers having lasers as light sources. As the light sources, semiconductor lasers are used in view of the cost, the size of apparatus and so forth. Semiconductor lasers prevailingly used at present have an oscillation wavelength of as long as 790 to 820 nm. Accordingly, electrophotographic photosensitive members having sufficient sensitivities in such a long-wavelength region are being developed.
Sensitivity regions of electrophotographic photosensitive members differ depending on the types of charge-generating materials. In recent years, as charge-generating materials having a sensitivity to long-wavelength light, substantial research has been conducted on metal phthalocyanines or metal-free phthalocyanines such as aluminum chlorophthalocyanine, chloroindium phthalocyanine, oxyvanadium phthalocyanine, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, magnesium phthalocyanine and oxytitanium phthalocyanine.
Of these phthalocyanines, oxytitanium phthalocyanine is disclosed in Japanese Patent Application Laid-open Nos. 61-217050, 61-239248, 64-17066 and 3-128973. Hydroxygallium phthalocyanine is disclosed in Japanese Patent Application Laid-open Nos. 5-263007 and 6-93203.
As a combination of charge-generating materials, Japanese Patent Application Laid-open Nos. 3-37666, 5-66596 and 7-128888 disclose an electrophotographic photosensitive member having a broad sensitivity wavelength region (i.e., panchromatic), using a phthalocyanine compound and an azo pigment in combination.
An electrophotographic photosensitive member making use of an oxytitanium phthalocyanine having the strongest peak at 27.2°±0.2° of the diffraction angle (2&thgr;) in CuK&agr; characteristic X-ray diffraction has a very high sensitivity and also a good charging performance, but those having much superior characteristics with respect to residual potential, photomemory and potential stability are under study. Also, an electrophotographic photosensitive member making use of a hydroxygallium phthalocyanine having strong peaks at 7.4°±0.2° and 28.2°±0.2° of the diffraction angle (2&thgr;) in CuK&agr; characteristic X-ray diffraction shows good results for sensitivity, residual potential and photomemory, but those having much superior characteristics with respect to charging performance and potential stability are being sought.
In order to improve characteristics, e.g., to broaden the sensitivity region, it is proposed to use a phthalocyanine compound and a azo pigment in combination. However, a difference in dispersibility between the phthalocyanine compound and the azo pigment requires a complicated dispersion method or results in an unstable dispersion in many cases. Also, from the viewpoint of achieving much higher process speed and much higher image quality, studies are being made on electrophotographic photosensitive members having much superior characteristics with respect to sensitivity, potential stability in repeated use, residual potential, black dots or fog due to faulty charging, and also memory to white light.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrophotographic photosensitive member having a low residual potential, free of any faulty charging, showing a small photomemory, promising a high image quality and high sensitivity characteristics, and having stable potential characteristics when used repeatedly.
Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus which employ such electrophotographic photosensitive member.
The present invention provides an electrophotographic photosensitive member comprising a support and a photosensitive layer provided on the support, the photosensitive layer containing an oxytitanium phthalocyanine having the strongest peak at 27.2°±0.2° of the diffraction angle (2&thgr;) in CuK&agr; characteristic X-ray diffraction and a hydroxygallium phthalocyanine having strong peaks at 7.4°±0.2° and 28.2°±0.2° of the diffraction angle (
2&thgr;) in CuK&agr; characteristic X-ray diffraction.
The present invention also provides a process cartridge comprising the above electrophotographic photosensitive member of the present invention and a means selected from the group consisting of a charging means, a developing means and a cleaning means, which are supported as one unit and being detachably mountable to the main body of an electrophotographic apparatus.
The present invention still also provides an electrophotographic apparatus comprising the above electrophotographic photosensitive member of the present invention, a charging means, an exposure means, a developing means and a transfer means.
REFERENCES:
patent: 4981767 (1991-01-01), Tokura et al.
patent: 5102758 (1992-04-01), Kazmaier et al.
patent: 5213929 (1993-05-01), Takano et al.
patent: 5578406 (1996-11-01), Ojima et al.
patent: 5595846 (1997-01-01), Shigematsu et al.
patent: 5725985 (1998-03-01), Nealy et al.
patent: 0638848 (1995-02-01), None
patent: 0803546 (1997-10-01), None
patent: 61-217050 (1986-09-01), None
patent: 61-239248 (1986-10-01), None
patent: 01-017066 (1989-01-01), None
patent: 03-037666 (1991-02-01), None
patent: 03-128973 (1991-05-01), None
patent: 05-066596 (1993-03-01), None
patent: 05-263007 (1993-10-01), None
patent: 06-093203 (1994-04-01), None
patent: 07-128888 (1995-05-01), None
Nakata Kouichi
Tanaka Masato
Canon Kabushiki Kaisha
Chapman Mark
Fitzpatrick ,Cella, Harper & Scinto
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