Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
2002-12-10
2003-12-09
Pendegrass, Joan (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S147000
Reexamination Certificate
active
06661442
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus which forms an electrostatic latent image on a latent image carrier by using writing electrodes of a writing device, thereby forming the image.
In a conventional image forming apparatus such as an electrostatic copying machine and a printer, the surface of a photoreceptor (photosensitive member) is uniformly charged by a charging device and the charged surface is then exposed to light from an exposure device such as laser beam or LED light, whereby a latent image is written on the surface of the photoreceptor. Then, the latent image on the surface of the photoreceptor is developed by a developing device to form a developing powder image on the surface of the photoreceptor. The developing powder image is transferred to a receiving medium such as a paper, thereby forming the image.
In such conventional image forming apparatus, the exposure device as a writing device for electrostatic latent image comprises a laser beam generating device or a LED light generating device. Therefore, the entire image forming apparatus should be large and complex.
Therefore, an image forming apparatus has been proposed in Japanese Patent Publication No. S63-45104 (hereinafter, '104B publication) which employs electrodes, as a writing device for forming an electrostatic latent image, to write an electrostatic latent image on a surface of a latent image carrier without using laser beams and LED lights.
The image forming apparatus disclosed in the '104B publication is provided with a multistylus having a large number of needle electrodes. The needle electrodes are just arranged in contact with an inorganic glass layer on the surface of the latent image carrier. In accordance with an input signal for image information, voltages are selectively applied to corresponding ones of the needle electrodes of the multistylus, whereby the electrostatic latent image can be formed on the latent image carrier. Since the image forming apparatus according to the '104B publication does not use an exposure device conventionally used as a writing device, the invention of this publication can provide an image forming apparatus which is relatively small in size and relatively simple in structure.
In addition, an image forming apparatus has been proposed in Japanese Unexamined Patent Publication No. H06-166206 (hereinafter, '206A publication), comprising ion control electrodes which are disposed on a front end portion of an insulating substrate and are arranged in non-contact with a latent image carrier, wherein the ion control electrodes control ions generated by a corona discharger so as to write an electrostatic latent image on the latent image carrier. Since the image forming apparatus according to the '206A publication also does not use an exposure device as a writing device, the invention of this publication can provide an image forming apparatus which is relatively small in size and relatively simple in structure.
However, in the image forming apparatus according to the '104B publication, the large number of needle electrodes of the multistylus are just arranged in contact with the inorganic glass layer on the surface of the latent image carrier. It is difficult to keep the stable contact between the needle electrodes and the inorganic glass layer on the surface of the latent image carrier. Accordingly, it is difficult to stably apply charge to the surface of the latent image carrier. This means that it is hard to obtain a high quality image.
Moreover, it is unavoidable to employ an inorganic glass layer on the surface of the latent image carrier for protecting the surface of the latent image carrier from damage due to contacts of a large number of the needle electrodes. This makes the structure of the latent image carrier more complex. In addition, since the inorganic glass layer has quite well physical adsorbed water characteristic, moisture is easily adsorbed by the surface of the inorganic glass layer. Due to the moisture, the electrical conductivity of the glass surface is increased so that electrostatic charge on the latent image carrier should leak. Therefore, the image forming apparatus should be provided with a means for drying the surface of the latent image carrier with adsorbed moisture in order to prevent the apparatus from being affected by absorbed water. This not only makes the apparatus larger but also increases the number of parts, leading to problems of making the structure further complex and increasing the cost.
Since the large number of needle electrodes discharge, the apparatus has another problem that there is a high possibility of generation of ozone (O
3
). The presence of ozone may not only produce rusts on parts in the apparatus but also melt resin parts because ozone reacts with NO
x
to generate nitrous acid (HNO
3
). Again ozone may give an offensive smell. Therefore, the image forming apparatus should be provided with an ventilation system including a duct and an ozone filter which sufficiently exhausts ozone from the inside of the apparatus. This also not only makes the apparatus larger but also increases the number of parts, leading to problems of making the structure further complex and increasing the cost.
On the other hand, in the image forming apparatus according to the '206A publication, ions produced by the corona discharger are controlled by the ion control electrodes. This means that the apparatus is structured not to directly inject electric charge to the latent image carrier. The invention of the '206A publication has problems of not only making the image forming apparatus larger and but also making the structure complex. Since the application of charge is conducted by ions, it is difficult to stably write a latent image on the latent image carrier.
Further, since the generation of ions essentially generates ozone, there are problems similar to those described with regard to the image forming apparatus according to '104B publication.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image forming apparatus capable of more stably writing an electrostatic latent image and yet achieving reduction in size and reduction in the number of parts thereof so as to have more simple and low-priced structure.
It is another object of the present invention to provide an image forming apparatus capable of further preventing generation of ozone.
In order to achieve these objects, the present invention provides an image forming apparatus which comprises at least: a latent image carrier on which an electrostatic latent image is formed, a writing device for writing said electrostatic latent image on said latent image carrier, and a developing device for developing said electrostatic latent image on the latent image carrier, wherein said electrostatic latent image, written on said latent image carrier by said writing device, is developed by said developing device, thereby forming an image, and is characterized in that said writing device has writing electrodes for writing said electrostatic latent image on said latent image carrier and a flexible substrate for supporting said writing electrodes, wherein said writing electrodes are in contact with said latent image carrier with a small pressing force due to elasticity of said flexible substrate, and that each of said writing electrodes comprises a convexity projecting from said substrate toward said latent image carrier.
The present invention is characterized in that said each writing electrode is formed in any one of configurations including a portion of sphere, a circular column, a cone, a truncated cone, an elliptic column (column of which cross section is elliptic), an elliptic cone (cone of which cross section is elliptic), a truncated elliptic cone (truncated cone of which cross section is elliptic), an oval column (column of which cross section is oval), an oval cone (cone of which cross section is oval), a truncated oval cone (truncated cone of which cross section is oval), a
Abe Nobumasa
Kamoshida Shinichi
Koga Yoshiro
Nomura Yujiro
Yoda Kaneo
Pendegrass Joan
Sughrue & Mion, PLLC
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