Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making radiation-sensitive product
Reexamination Certificate
2002-09-27
2003-10-14
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making radiation-sensitive product
C430S133000, C430S134000, C430S057400, C430S059100
Reexamination Certificate
active
06632578
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present 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.), and also relates to a process for its production.
2. Description of the Related Art
In the field of image formation, photoconductive materials that form light-receiving layers in light-receiving members are required to have properties such that 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 electrophotographic light-receiving members set in electrophotographic apparatus used in offices, their safety during use an important point.
Photoconductive materials having good properties in these respects include amorphous silicon hydrides (hereinafter “a-Si:H”). For example, U.S. Pat. No. 4,265,991 discloses its application in electrophotographic light-receiving members. In such electrophotographic light-receiving members having a-Si:H, it is common to form photoconductive layers comprised of a-Si, by film forming processes such as vacuum deposition, sputtering, ion plating, heat-assisted CVD, light-assisted CVD and plasma-assisted CVD while heating conductive to from 50° C. to 350° C. In particular, the plasma-assisted CVD, i.e., a process in which material gases are decomposed by direct-current, high-frequency or microwave glow discharging to form a-Si deposited films on the support, has been put into practical use as a preferred process.
U.S. Pat. No. 5,382,487 discloses an electrophotographic light-receiving member comprising a conductive support and an amorphous silicon photoconductive layer containing a halogen atom as a constituent (hereinafter “a-Si:X” photoconductive layer). This publication discloses that incorporation of 1 to 40 atom % of halogen atoms into a-Si 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 also 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 photoconductive members having a photoconductive layer formed of an a-Si deposited film, in respect of their 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 respect of stability with time. Japanese Patent Publication Laid-Open No. 60-67951 also discloses a technique concerning a photosensitive member laminated with a light-transmitting insulating overcoat layer containing amorphous silicon, carbon, oxygen and fluorine. U.S. Pat. No. 4,788,120 still also 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.
U.S. Pat. No. 4,409,311 further discloses that a highly sensitive and highly resistant, electrophotographic photosensitive member can be obtained by using in a photoconductive layer an a-Si:H containing 10 to 40 atom % of hydrogen atoms and having absorption peaks at 2,100 cm
−1
and 2,000 cm
−1
in an infrared absorption spectrum which peaks are in a ratio of 0.1 to 1.7 as the coefficient of absorption. Japanese Patent Publication Laid-Open No. 62-83470 further discloses a technique in which a high quality image without after image can be obtained by reducing, to 0.09 eV or less, the characteristic energy of the exponential tail in a light absorption spectrum of a photoconductive layer of an electrophotographic photosensitive member.
Meanwhile, U.S. Pat. No. 4,607,936 discloses a technique in which, aiming at an improvement in image quality of an amorphous silicon photosensitive member, image forming steps such as 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 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 comprising an a-Si 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 durability. Under existing circumstances however, there is room for further improvements to make overall properties better. In particular, there is a rapid progress in making electrophotographic apparatus have higher image quality, higher speed and higher durability, and the electrophotographic light-receiving members are required to be more improved in electrical properties and photoconductive properties and also to be significantly decreased in variations in their properties in every environment while being improved in charge performance and sensitivity.
Then, as a result of improvements made on optical exposure devices, developing devices, transfer devices and the like in order to improve image characteristics of electrophotographic apparatus, the electrophotographic light-receiving members are now also required to be more improved in performance than ever.
Under such circumstances, although the conventional techniques as described above have made it possible to improve properties to a certain degree in respect of the above-described subjects, they cannot be said to be satisfactory in regard to additional enhancement in charge performance and image quality. In particular, as the subjects for making amorphous silicon light-receiving members have much higher image quality, it has now been sought to further improve the charge performance and decrease variations in the charge performance due to changes in environmental temperature and exposure memory such as blank memory and ghost. For example, an electrophotographic apparatus is miniaturized year by year from the viewpoint of space saving, and the space around a photosensitive member in the electrophotographic apparatus tends to be decreased concurrently. As a result, although a charger is miniaturized, it becomes difficult to increase the capacity of a power source for the charger from the viewpoint of power consumption, thereby causing difficulties in ensuring a sufficient surface potential.
For example, hitherto, in order to prevent smeared images caused by photosensitive members, a drum heater is set inside a copying machine to keep the surface temperature of a photosensitive member at about 40° C., as disclosed in Japanese Patent Publication Laid-Open No. 60-95551. In conventional photosensitive members, however, the dependence of charge performance on temperature, so-called temperature-dependent properties, which is ascribable to formation of pre-exposure carriers or heat-energized carriers is so great that, in the actual service environment inside copying machines, photosensitive members were sometimes used with lower charge performance than that o
Kojima Satoshi
Niino Hiroaki
Tsuchida Shinji
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