Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
2002-09-18
2004-06-15
Pendegrass, Joan (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S141000, C399S313000
Reexamination Certificate
active
06750891
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus which forms an electrostatic latent image on an image carrier by using writing electrodes of a writing head, thereby forming the image.
In a conventional image forming apparatus such as an electrostatic copying machine and a printer, the surface of a photoreceptor is uniformly charged by a charging device and the uniformly charged surface of the photoreceptor is then exposed to light from an exposure device such as laser beam or LED light, whereby an electrostatic latent image is written on the surface of the photoreceptor. Then, the electrostatic latent image on the surface of the photoreceptor is developed by a developing device to form a developer image on the surface of the photoreceptor. The developer image is transferred to a recording 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 image carrier without using any of laser beams and LED lights.
The image forming apparatus disclosed in the '104B publication is provided with a multi-stylus 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 image carrier. In accordance with an input signal for image information, voltage is selectively applied to corresponding ones of the needle electrodes of the multi-stylus, whereby the electrostatic latent image can be formed on the 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 makes it possible to 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 an image carrier, wherein the ion control electrodes control ions generated by a corona discharger so as to write an electrostatic latent image on the 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 makes it possible to 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 multi-stylus are just arranged in contact with the inorganic glass layer on the surface of the image carrier. It is difficult to keep the stable contact between the needle electrodes and the inorganic glass layer on the surface of the image carrier. Accordingly, it is difficult to stably apply charge to the surface of the 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 image carrier for protecting the surface of the image carrier from damage due to contacts of the large number of needle electrodes. This makes the structure of the 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 image carrier should leak. Therefore, the image forming apparatus should be provided with a means for drying the surface of the 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 nitric acid (HNO
3
). Again ozone may give an offensive smell. Therefore, the image forming apparatus should be provided with a 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 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 an electrostatic latent image on the 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.
In order to solve the above problems, the applicant of this application filed a patent application to Japanese Patent Office (Japanese Patent Application No. 2001-227630, hereinafter '630 application) proposing an image forming apparatus which makes it possible to reduce the size thereof and reduce the number of parts thereof so as to have more simple and low-priced structure, to more stably write an electrostatic latent image, and to inhibit the generation of ozone.
Since the details of the image forming apparatus proposed in the '630 application will be easily understood by persons skilled in the art on consideration of the specification and drawings of the patent application, the details thereof will be omitted here. Only parts directly related to the present invention will be briefly described.
FIG. 1
is an illustration schematically showing the basic structure of the image forming apparatus proposed in the '630 application.
As shown in
FIG. 1
, the image forming apparatus
1
comprises an image carrier
2
having a substrate
2
a
which is made of a conductive material such as aluminum and is grounded and a chargeable layer
2
d
which is formed on the outer periphery of the substrate
2
a
and has an insulating property and on which a electrostatic latent image is formed, a writing head
3
having a flexible substrate
3
a
, having high insulation property and being relatively soft and elastic, such as a FPC (Flexible Print Circuit: hereinafter, referred to as “FPC”) or a PET (polyethylene terephthalate: hereinafter, referred to as “PET”), and writing electrodes
3
b
which are supported by the substrate
3
a
and which are pressed lightly against the image carrier
2
with weak elastic restoring force created by deflection of the substrate
3
a
so that the writing electrodes
3
b
are in plane contact with the charged layer of the image carrier
2
to write the electrostatic latent image, a developing device
4
having a developer carrier (hereinafter, sometimes referred to as “development roller”)
4
a
, and a transferring de
Kamoshida Shinichi
Yoshioka Kenjiro
Pendegrass Joan
Seiko Epson Corporation
Sughrue & Mion, PLLC
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