Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-04-26
2004-07-20
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S047300, C430S046400, C399S302000, C399S308000, C399S159000, C399S306000, C399S303000, C399S299000
Reexamination Certificate
active
06764800
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image-forming process applicable to copying machines, printers, facsimile machines, and the like, and a photosensitive member employed for the image-forming process. More specifically, the present invention relates to an image-forming process applicable to copying machines, printers, facsimile machines, and the like, comprising steps of forming a toner image on a photosensitive member having on a substrate a photoconductive layer typified by a-Si, and transferring the toner image onto a transfer-receiving medium; and relates also a photosensitive member employed for the image-forming process.
2. Related Background Art
Image forming apparatuses employing an electrophotographic process are known which forms a synthetic color image by decomposing a color image information or a multicolor information into its color components, forming a latent image corresponding to the respective color components on a photosensitive member, forming a toner image on the latent image, transferring the toner image of this color component temporarily on an intermediate image-transfer element, and further transferring onto this toner image another color component toner image in superposition. The image forming apparatus employing such an intermediate image-transfer element is useful as a color image forming apparatus, a multiple color image forming apparatus, or an image forming apparatus equipped with a color image forming mechanism or a multiple color image forming mechanism since the apparatus gives color images with sufficient superposition (registration) of component color images. Color copying machines and color printers equipped with such an image forming apparatus have come to be marketed.
Another type of image forming apparatuses are known which transfers successively color-component images of color image information or of multicolor image information directly onto a recording sheet conveyed by an image-transferring belt to output a synthesized color image or multicolor image. The image forming apparatus employing such an image-transferring belt is useful as a color image forming apparatus, or a multiple color image forming apparatus. The image forming apparatus employing the image-transferring belt is also useful as an image forming apparatus for high-speed formation.
The image forming apparatuses employing an intermediate image-transfer element or an image-transferring belt are disclosed in Japanese Patent Application Laid-Open Nos. 8-320591, 8-211757, 8-160759, 2001-51524, and so forth.
As a photosensitive material, a-Si absorbs moisture on its surface under high humidity conditions, which tends to cause smudging of the toner image to result in blurring of the formed image. Smudging the toner is not the only condition, which adversely affects the quality of the image. Other conditions affecting the quality of the image include adhering matters include various foreign matters deposited onto the photosensitive material surface such as fine dust of paper usually used as the recording sheet, organic components released from the paper, and corona products generated by corona discharge at a high voltage in the apparatus. In particular, under high humidity conditions, the deposited matter lowers the resistivity of the photosensitive material, resulting in lower sharpness of the latent image and lower quality of the recorded image. To prevent the image blurring simply and effectively, usually the moisture absorption on the photosensitive material surface is prevented by employing a heater to apply electric current throughout whole days.
Such image forming apparatuses are required to save energy and to decrease industrial waste so as not to cause environmental pollution as in Blue Angel and Energy Star Program. Therefor, a method for preventing the image blurring on the a-Si photosensitive material is demanded which does not require a waiting power of the aforementioned whole-day electricity application system. Further, elongation of the lives of the members like the photosensitive member, the intermediate image-receiving member, and image transfer belt of the electrophotography apparatus is required to decrease waste.
The a-Si photosensitive material has a significantly high hardness (Vickers hardness ranging from 1500 to 2000 kg/mm
2
), and is much less surface-abradable than other photosensitive materials such as organic photosensitive materials and selenium type photosensitive materials (Vickers hardness ranging from 50 to 150 kg/mm
2
). Specifically the abrasion loss of the a-Si by image formation of several ten thousands of sheets is only several nanometers. The organic photosensitive member or the selenium type photosensitive member is abraded at the surface during use to produce fresh surface incessantly, whereby the adverse effect of the adhering matter is reduced, even when melt adhesion of a toner or deposition of a foreign matter occurs. In contrast, the a-Si photosensitive material, which is abraded less at the surface, is liable to cause significant adhesion of the melted toner or deposition of a foreign matter depending on the constitution. Therefore, the a-Si photosensitive material changes greatly the sildability on contacting members such as a cleaning blade by adhesion of the melted toner or deposition of the foreign matter in a small amount to cause vibration (so-called chattering vibration) of the cleaning blade or uneven distribution of the load, resulting in frequent cleaning failure.
The intermediate image-transfer element or the image-transferring belt is brought into contract with the photosensitive member with a nip contact breadth of several millimeters at a contact pressure ranging from 5 to 1000 g/cm
2
(0.49 to 98.1 kPa). The intermediate image-transfer element or the image-transferring belt is repeatedly attached to and detached from the copying paper sheet, which may cause fine vibration (chattering vibration). When the vibration is strong, the transferred toner image can be blurred or not to be registered to impair the image quality directly. Even when the vibration is not so strong, the energy generated by the vibration may cause toner melt adhesion, filming, adhesion of talc or paper dust onto the intermediate image-transfer element or the image-transferring belt to cause an image defect in a stripe state or a dot state, or to cause blurring of the image by high-temperature and high-humidity conditions (30° C., 80% RH or higher) on the photosensitive member surface disadvantageously. The toner melt adhesion or foreign matter deposition tends to occur especially at the contact position (nip) of the photosensitive member with the intermediate image-transfer element or the image-transferring belt.
Hitherto, such problems have been dealt with by changing the material of or the shape of the intermediate image-transfer element of the image-transferring belt, contact conditions, and stretching conditions thereof. However, a-Si has not been studied as the factor for preventing the fine vibration, toner melt adhesion, and foreign matter deposition, so that the problem has not been solved satisfactorily.
In the recent years, electrophotographic image forming apparatuses having a printer function in addition to the copying function have come to be widely used. For such apparatuses, accessories such as a feeder mechanism and a sorter mechanism are developed. With such development, continuous image formation on 4000 sheets or more of recording sheets can be practicable in one job. In such recording operation, for example, at an image formation rate of 50 sheets (A4-size, 210 mm×297 mm) per minute, the 4000 sheet (A4-size) of image formation will be continued for 80 minutes or longer by simple calculation. Such a long time of continuous operation will elevate the ambient temperature up to about 50° C. around the photosensitive member, and can elevate the temperature at the contact portion between the photosensitive member and the intermediate image-transfer element or between the p
Karaki Tetsuya
Kawada Masaya
Kobayashi Hiroyuki
Owaki Hironori
Yamazaki Koji
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Rodee Christopher
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