Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-07-30
2001-02-06
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S075000, C430S078000
Reexamination Certificate
active
06183922
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus, and more particularly to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus which are suited for short-wavelength semiconductor lasers capable of making images have higher resolution.
2. Related Background Art
In electrophotographic apparatus making use of lasers as light sources as typified by laser printers, semiconductor lasers having oscillation wavelength around 800 nm or around 680 nm are prevailingly used. In recent years, various approaches to higher resolution are made with an increase in demand for reproducing images having a higher image quality. Wavelengths of lasers also deeply concern the higher resolution. As disclosed in Japanese Patent Application Laid-Open No. 9-240051, the shorter oscillation wavelength a laser has, the smaller spot diameter the laser can have. This enables formation of latent images having a high resolution.
Some methods are available for making laser oscillation wavelength shorter.
One of the methods is a method in which a non-linear optical material is utilized so that the wavelength of laser light is shortened to half by using secondary higher harmonic generation (SHG) (e.g., Japanese Patent Applications Laid-Open No. 9-275242, No. 9-189930 and No. 5-313033). This system can achieve a long life and a large output, since it can use GaAs semiconductor lasers or YAG lasers as primary light sources, which have already established their technique and can achieve a high output.
Another is a method in which a wide-gap semiconductor is used, and can make apparatus smaller in size than devices utilizing the SHG. ZnSe semiconductor lasers (e.g., Japanese Patent Applications Laid-Open No. 7-321409 and No. 6-334272) and GaN semiconductor lasers (e.g., Japanese Patent Applications Laid-Open No. 8-088441 and No. 7-335975) have long been studied in great deal because of their high emission efficiency.
It, however, has been difficult for these semiconductor lasers to be optimized in their device structure, crystal growth conditions and electrodes, and, because of defects in crystals, has been difficult to make long-time oscillation at room temperature, which is essential for putting them into practical use.
However, with progress of technological innovations on substrates and so forth, Nichia Kagaku Kogyo K.K. reported, in October, 1997, GaN semiconductor laser's continuous oscillation for 1,150 hours (condition: 50° C.), and materialization for its practical use stands close at hand.
Japanese Patent Application Laid-Open No. 9-240051 discloses as a photosensitive member suited for 400 to 500 nm lasers a multi-layer photosensitive member in which a single layer or charge generation layer making use of &agr;-type titanyl phthalocyanine is formed as the outermost layer. Studies made by the present inventors, however, have revealed that the use of such a material brings about such a problem that, because of a poor sensitivity and a very great memory especially for light of about 400 nm, photosensitive members may undergo great potential variations when used repeatedly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity characteristics even in a wavelength region of 380 to 500 nm and also having small photomemory and undergoing small potential variations when used repeatedly, and a process cartridge having such a photosensitive member, and also provides an electrophotographic apparatus that is practical and can stably reproduce images with a high image quality by using such a photosensitive member and a short wavelength laser.
The present invention provides an electrophotographic photosensitive member comprising a support and a photosensitive layer provided thereon, and being exposed to semiconductor laser light having a wavelength of from 380 nm to 500 nm;
the photosensitive layer containing an azo pigment represented by the following Formula (1).
Ar&Parenopenst;N═N—Cp)
n
(1)
wherein Ar represents a substituted or unsubstituted aromatic hydrocarbon cyclic group or heterocyclic group which may be bonded directly or via a linking group; Cp represents a coupler residual group represented by the following Formula (2), (3), (4) or (5); and n represents an integer of 1 to 3; provided that a plurality of —N═N—Cp moieties are not bonded to the same benzene ring.
wherein X represents a residual group necessary for condensing with the benzene ring to form a polycyclic aromatic ring or heterocyclic ring; R
1
and R
2
each represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group, and R
1
and R
2
may form a cyclic amino group via the nitrogen atom in the formula; Z
1
represents an oxygen atom or a sulfur atom; and m
1
represents an integer of 0 or 1.
wherein Y represents a substituted or unsubstituted divalent aromatic hydrocarbon cyclic group or a substituted or unsubstituted divalent nitrogen-containing heterocyclic group.
wherein R
3
represents a hydrogen atom, a halogen atom, a cyano group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group or a nitro group; R
4
represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; R
5
represents a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyl group, a cyano group or a nitro group; and l represents an integer of 0 to 2, and, when l is 2, R
5
's may be different groups.
wherein R
6
and R
7
each represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group, and R
6
and R
7
may form a cyclic amino group via the nitrogen atom in the formula; Z
2
represents an oxygen atom or a sulfur atom; and m
2
represents an integer of 0 or 1.
The present invention also provides a process cartridge having the electrophotographic photosensitive member described above.
The present invention still also provides an electrophotographic apparatus comprising the electrophotographic photosensitive member described above and a short-wavelength semiconductor laser as an exposure light source.
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Patent Abstracts and Japan, vol. 1998, No. 1 (Jan. 1998) for JP 09-240051.
Takai Hideyuki
Tanabe Kan
Tanaka Masato
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Goodrow John
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