Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1997-09-10
2002-04-30
Rodee, Christopher (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
Reexamination Certificate
active
06379852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electrophotographic light-receiving member having a sensitivity to electromagnetic waves such as light (which herein refers to light in a broad sense and indicates ultraviolet rays, visible rays, infrared rays, X-rays, &ggr;-rays, etc.).
2. Related Background Art
In the field of image formation, photoconductive materials that form light-receiving layers of light-receiving members are required to have properties as follows: They are highly sensitive, have a high SN ratio [light current (Ip)/dark current (Id)], have absorption spectra suited to spectral characteristics of electromagnetic waves to be radiated, have a high response to light, have the desired dark resistance and are harmless to human bodies when used. In particular, in the case of light-receiving members set in electrophotographic apparatus used as business machines in offices, the safety in their use is important.
Photoconductive materials having good properties in these respects include amorphous silicon hydrides. For example, U.S. Pat. No. 4,265,991 discloses its application in electrophotographic light-receiving members.
In the production of such light-receiving members, it is common to form photoconductive layers comprised of amorphous silicon, by film forming processes such as vacuum deposition, sputtering, ion plating, heat-assisted CVD, light-assisted CVD and plasma-assisted CVD, which layers are formed on conductive supports while heating the supports at 50° C. to 350° C. In particular, their production by plasma-assisted CVD is preferable and has been put into practical use. This plasma-assisted CVD is a process in which material gases are decomposed by high-frequency or microwave glow discharging to form amorphous silicon deposited films on the conductive support.
U.S. Pat. No. 5,382,487 discloses an electrophotographic light-receiving member having a photoconductive layer formed of amorphous silicon containing halogen atom. This publication reports that incorporation of 1 to 40 atom % of halogen atoms into amorphous silicon enables achievement of a high thermal resistance, and also electrical and optical properties preferable for a photoconductive layer of an electrophotographic light-receiving member.
Japanese Patent Application Laid-open No. 57-115556 discloses a technique in which a surface barrier layer formed of a non-photoconductive amorphous material containing silicon atoms and carbon atoms is provided on a photoconductive layer formed of an amorphous material mainly composed of silicon atoms, in order to achieve improvements in electrical, optical and photoconductive properties such as dark resistance, photosensitivity and response to light and service environmental properties such as moisture resistance and also in stability with time. Japanese Patent Application Laid-open No. 60-67951 also discloses a technique concerning a photosensitive member superposingly provided with a light-transmitting insulating overcoat layer containing amorphous silicon, carbon, oxygen and fluorine. Japanese Patent Application Laid-open No. 62-168161 discloses a technique in which an amorphous material containing silicon atoms, carbon atoms and 41 to 70 atom % of hydrogen atoms as constituents is used to form a surface layer.
Japanese Patent Application Laid-open No. 58-21257 discloses a technique in which support temperature is changed in the course of the formation of a photoconductive layer and inhibition bandwidth is changed in the photoconductive layer to thereby obtain a photosensitive member having a high resistance and a broad photosensitive region. Japanese Patent Application Laid-open No. 58-121042 discloses a technique in which energy gap state density is changed in the direction of layer thickness of a photoconductive layer and the energy gap state density of a surface layer is controlled to be 10
17
to 10
19
cm
−3
to thereby prevent surface potential from being reduced because of humidity. Japanese Patent Application Laid-open No. 59-143379 and No. 61-201481 disclose a technique in which amorphous silicon hydrides having different hydrogen contents are superposingly formed to obtain a photosensitive member having a high dark resistance and a high sensitivity.
Japanese Patent Application Laid-open No. 58-88115 discloses that, aiming at an improvement in image quality of an amorphous silicon photosensitive member, atoms of Group III of the Periodic Table are incorporated in a large quantity on the support side of a photoconductive layer. Japanese Patent Application Laid-open No. 62-83470 discloses a technique in which characteristic energy of an exponential tail of light absorption spectra is controlled to be not more than 0.09 eV in a photoconductive layer of an electrophotographic photosensitive member to thereby obtain high-quality images free of after-image development. Japanese Patent Application Laid-open No. 62-112166 also discloses a technique in which flow rate ratio of B
2
H
6
/SiH
4
is maintained at 3.3×10
−7
or above to form a carrier transport layer to thereby make free of after-image development.
Further, Japanese Patent Application Laid-open No. 60-95551 discloses a technique in which, aiming at an improvement in image quality of an amorphous silicon photosensitive member, image forming steps of charging, exposure, development and transfer are carried out while maintaining temperature at 30 to 40° C. in the vicinity of the surface of the photosensitive member to thereby prevent the surface of the photosensitive member from undergoing a decrease in surface resistance which is due to water absorption on that surface and also prevent smeared images from occurring concurrently therewith.
These techniques have achieved improvements in electrical, optical and photoconductive properties and service environmental properties of electrophotographic light-receiving members, and also have concurrently brought about an improvement in image quality.
The electrophotographic light-receiving members having a photoconductive layer comprised of an amorphous silicon material have individually achieved improvements in properties in respect of electrical, optical and photoconductive properties such as dark resistance, photosensitivity and response to light and service environmental properties and also in respect of stability with time, and running performance (durability). However, improvements are still unsatisfactory from an overall viewpoint, and there is room for further improvements to make overall properties better.
In particular, there has been rapid progress in making electrophotographic apparatus have higher image quality, higher speed and higher running performance, and the electrophotographic light-receiving members are required to be more improved in electrical properties and photoconductive properties and also to greatly improve their performances in every environment while maintaining chargeability and sensitivity. Then, as a result of improvements made on optical exposure devices, developing devices, transfer devices and so forth in order to improve image characteristics of electrophotographic apparatus, the electrophotographic light-receiving members are now also required to be more improved in image characteristics than ever before.
Under such circumstances, although the conventional techniques as noted above have made it possible to improve properties to a certain degree in respect of the subjects stated above, they still can not be said to be satisfactory in regard to the improvements in chargeability, sensitivity, response to light, and image quality. In particular, as the subjects for making amorphous silicon light-receiving members have much higher image quality, it has now been also sought to prevent variations of electrophotographic performances (e.g., chargeability and sensitivity) due to changes in surrounding temperature (i.e., improve service environmental properties) and to make photomemory such as blank memory and ghost occur less (i.e., improve photoconductive chara
Kojima Satoshi
Niino Hiroaki
Tsuchida Shinji
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Rodee Christopher
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