Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2001-05-18
2003-03-18
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C399S159000, C399S359000
Reexamination Certificate
active
06534228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The prevent invention relates to a photosensitive member formed by stacking in order a photoconductive layer containing amorphous Si and a surface protective layer, and to an image forming apparatus represented by an electrophotographic apparatus comprising the photosensitive member of the present invention.
2. Related Background Art
In the electrophotographic apparatus such as a copier, a facsimile, a printer or the like, an outer peripheral surface of the photosensitive member disposed with a photoconductive layer on its surface is uniformly charged by charging means such as corona charging, roller charging, fur brush charging, magnetic brush charging or the like and then the image of an object to be copied is exposed by laser or LED responding to a reflective light or a modulation signal, whereby an electrostatic latent image is formed on the outer peripheral surface of the above described photosensitive member. Further toner is adhered on the photosensitive member and then it is transferred to a copy paper or the like to complete copy.
After completing copy in this way by the electrophotographic apparatus, because toner remains on the outer peripheral surface of the photosensitive member, it is necessary to remove the remained toner. The removal of such remained toner is usually performed by a cleaning step using a cleaning blade, a fur brush, a magnetic brush or the like.
Also, in recent years, from the environmental concern, for the purpose of reducing or canceling waste toner, an electrophotographic apparatus omitting a cleaning equipment is proposed and disclosed. This system is a direct charger similar to a brush charger such as disclosed in Japanese Patent Application Laid-Open No. 6-118741 which serves as a cleaning step, or a developing device such as disclosed in Japanese Patent Application Laid-Open No. 10-307455 which serves as a cleaning step, or the like, but each system includes a step of rubbing the toner and the photosensitive member surface together to remove the toner.
Since the amorphous silicon photosensitive member has a large surface hardness and a small wear amount, a low resistance material contained in a charging product and a transfer paper is difficultly removed in the above described cleaning step from the photosensitive member, whereby the electrophotographic apparatus using the photosensitive member easily generates a high-humidity smearing, and efforts for preventing this has been still continued since from the past. Concretely, in order to remove a moisture content by heating with a heater, removal of a substance causing the smearing by rubbing means and use of a surface protective material which is difficultly oxidized or adhered by the substance causing the smearing or the like are enumerated, which show an effect.
However, with recent rapid advancement of digitalization, when an image is created by collection of fine dots, the high-humidity smearing tends to appear particularly in a half-tone image. This necessitates further an improved performance.
For one of replies as the measure to prevent the high-humidity smearing concerning the present invention, as disclosed in Japanese Patent Application Laid-Open No. 9-204056, there is proposed a method wherein in a photosensitive member having amorphous silicon as its sensitive layer, the carbon amount of the surface of an electroconductive substrate which forms the photosensitive layer is increased so as not to be oxidized but easy to wear out the surface and at the same time the smoothness of the surface is enhanced so that removal of the substance causing the high-humidity smearing is made easy. This is defined by a value of the surface roughness measured by a surface roughness tester.
Also, in Japanese Patent Application Laid-Open No. 10-333350, there is disclosed a method wherein the photosensitive surface is polished inside the electrophotographic apparatus and the surface thereof is made flat, thereby achieving the same effect.
Further, with improvement of recent high picture quality of printed images, the toner having an average particle size smaller than the conventional one or the toner having a low melting point corresponding to an energy saving has come to be used, and not only in the above described cleaning step but also in a toner removal step performed at the same time with other steps, removal of the remained toner becomes difficult, and repeated copying sometimes leads to a problem of toner adherence wherein the remained toner adheres to the photosensitive member surface and thereby an image defect having a black point or a white point in the image is generated.
As a measure for solving the above described problem, as disclosed in Japanese Patent Application Laid-Open No. 9-297420, there is proposed a method of previously making rough the surface of the electroconductive substrate on which the sensitive layer is formed by cutting or a rotary ball mill equipment, in the photosensitive member having amorphous Si as its sensitive layer. The surface of the substrate is regulated by a value of the surface roughness of &mgr;m order measured by the surface roughness tester.
Also, in Japanese Patent Application Laid-Open No. 8-129266, a value of the surface roughness Ra is regulated. However, this regulates a processing shape of the electroconductive substrate and the substrate surface is regulated by a value of the surface roughness of &mgr;m order measured by the surface roughness tester.
However, due to the from recent advancement of digitalization of the electrophotographic apparatus and enhanced awareness of ecology, while the fact that an amorphous photosensitive member is still used, prolongation of the life of the photosensitive member and an energy saving are further required.
Concretely, the attempt of raising the life of the photosensitive member of a low speed, a medium speed printer for personal use or the like to the level equal to or more than the life of the main apparatus, reducing a waste material and abolishing the use of a photosensitive member heater of a high speed printer for office use or the like while maintaining its life at a level equal to or more than the life of the main apparatus are required.
For this purpose, the photosensitive member is required to have such a constitution as to prevent the high-humidity smearing without depending on a wear or a polish which imposes a limit to the life of the photosensitive member, that is, to satisfy all the above even when the photosensitive member heater is abolished.
Also, in recent years, accompanied by advancement of digitalization of an electrophotographic apparatus, a latent image formation by a light source mainly comprising a single wavelength is becoming the mainstream. This sometimes leads to a problem that the above proposed method of cutting the substrate in advance causes a difference in an incident exposure amount to photoconductive layers due to the substrate shape and as a result a stripe pattern is generated on the printed image. Also, in order to prevent an interference fringe by reflection of light which reaches the substrate, the establishment of a new step of previously making the surface of the electroconductive substrate rough leads to a high cost. On the contrary, when the substrate is processed within the range of roughness where the above described stripe pattern is not generated, the toner adherence can not be sufficiently inhibited.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrophotographic photosensitive member and an electrophotographic apparatus capable of preventing a high-humidity smearing and forming an excellent image.
Another object of the present invention is to provide a photosensitive member and an image forming apparatus which prevents the high-humidity smearing at the time of cleaning and achieves the excellent image formation.
Still another object of the present invention is to provide a photosensitive member and an image forming apparatus which prevents the toner adherence at the ti
Ehara Toshiyuki
Karaki Tetsuya
Kawada Masaya
Kawamura Kunimasa
Ohwaki Hironori
Canon Kabushiki Kaisha
Fitzpatrick,Cella,Harper&Scinto
Goodrow John
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