Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-04-28
2001-01-09
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S066000
Reexamination Certificate
active
06171742
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a photosensitive member to be used for an image-forming apparatus and also to an image-forming apparatus comprising such a photosensitive member. More particularly, it relates to a photosensitive member to be used for an image-forming apparatus adapted to electrostatically charge the surface of its photosensitive member operating as image carrier, writing image information on the electrostatically charged surface by means of a beam of visible light or a linear-scanning laser beam, forming a toner image and transferring the image onto a transfer medium to produce an image thereon and comprising a cleaning means for cleaning the surface of the photosensitive member. It also relates to a such an image-forming apparatus.
More specifically, the present invention relates to a photosensitive member to be used for an image-forming apparatus adapted to define the surface characteristics including the amount of surface free energy (&ggr;) and control the foreign matters adhering to the surface so as to make it apt to form images with a good image quality for a prolonged period of time regardless of fluctuations of environmental factors including moisture and temperature. It also relates to an image-forming apparatus comprising such a photosensitive member.
2. Related Background Art
Currently available image-forming apparatus, electrophotographic apparatus in particular, include printers operating as output means of computers and word processors that have been finding an ever-increasing demand in recent years as well as copying machines. Since such apparatus are operated in a variety of operating environments, they are often provided with a means for stabilizing the output image such as a means for eliminating the influence of fluctuations of environmental factors on the density of the output image. In addition, such printers are required to be low cost and maintenance free particularly because they are used not only for office applications but also for home or personal applications.
Still additionally, such printers are required to be friendly to the environment from the ecological point of view and hence should be adapted to print on the both sides of paper and on recycled paper, and reduce the consumption rate of paper and electric power.
FIG. 1
is a schematic illustration of an image-forming apparatus, illustrating the image-forming process of a copying machine.
Referring to
FIG. 1
, reference numeral
101
denotes a photosensitive member of the image-forming apparatus, which can rotate toward X-direction as indicated, to be used with an electrophotographic system (hereinafter simply referred to as “photosensitive member”), which is surrounded by a principal charging unit
102
, an electrostatic latent image forming site
103
, a developing unit
104
, a transfer paper feeding system
105
, a transfer charging unit
106
(
a
), a separation charging unit
106
(
b
), a cleaner unit
107
, a delivery system
108
and a conditioning light source
109
arranged clockwise in FIG.
1
. If necessary, the photosensitive member
101
may be provided with a circumferential internal surface heater
125
for controlling the temperature of the photosensitive member
101
.
The surface of the photosensitive member
101
is uniformly and electrostatically charged and, in operation, exposed to light at the electrostatic latent image forming site
103
to form an electrostatic latent image thereon.
The electrostatic latent image is then turned into a visible toner image by the developing sleeve of the developing unit
104
that carries toner on the surface.
Meanwhile, transfer medium P is fed from the transfer paper feeding system
105
as it is guided by a transfer paper guide
119
and its leading edge is registered by register rollers so that the toner image formed on the surface of the photosensitive member
101
is transferred onto the transfer medium P by means of the transfer charging unit
106
(
a
). Then, the transfer medium P is separated from the photosensitive member
101
by means of the separation charging unit
106
(
b
) and/or a separation means such as a separation pawl (not shown) and subsequently the toner image on the surface of the paper is moved to a fixing unit
123
by means of the delivery system
108
, where the toner image is fixed by fixing rollers
124
arranged in the fixing unit
123
before it is delivered to the outside of the image-forming apparatus.
On the other hand, after the toner image is transferred to the transfer medium P, the surface of the photosensitive member
101
is cleaned by a cleaning blade
120
and a cleaning roller (or brush)
121
arranged in the cleaning unit to remove the residual toner and the fine particles of paper adhering to the surface in order to make it ready for the next image forming operation.
As described above, an image-forming apparatus adapted to repeat the operation of forming an image by transferring a toner image on the surface of a photosensitive member onto a transfer medium such as paper needs to be provided with a cleaning means for removing the foreign matters remaining on the surface of the photosensitive member including the residual toner.
Such a cleaning unit
107
typically comprises a cleaning blade made of resin such as rubber and a cleaning brush made of resin fiber. The powdery magnetic objects remaining on the surface of the photosensitive member such as the residual toner may alternative be removed by means of magnetic adsorption.
Now, such a cleaning unit and cleaning means that can be used for the unit will be described below by referring to FIG.
2
.
FIG. 2
is a schematic view of a cleaning unit that can be used for the image-forming apparatus of FIG.
1
.
Cleaning means that can be used for the cleaning unit
301
of
FIG. 2
may comprise a cleaning blade
302
made of urethane rubber, a cleaning roller
303
made of silicon rubber, sponge or a magnetic material, a doctor roller
304
, a waste toner pool
305
and a waste toner delivery system
306
.
The doctor roller
304
may be arranged whenever necessary and may show a blade-like shape. Then, it will be referred to as scraper (or doctor blade).
For the purpose of simplification, the scraper will be omitted from the following description of the components of the cleaning unit.
Referring to
FIG. 2
, reference numeral
301
denotes a cleaning unit comprising a cleaning blade
302
made of a material obtained by mixing urethane rubber and one or more than one silicon compounds to have appropriate elasticity and hardness.
A cleaning roller
303
made of a magnet is arranged at an upstream position (lower position in
FIG. 2
) relative to the cleaning blade
302
in the sense of rotation of the photosensitive member. The cleaning roller
303
attracts powdery magnetic materials including the toner by its magnetic force and hence comes to be coated with the adherers. Thus, the coat of the powdery magnetic materials abuts the surface of the photosensitive member with an appropriate abutting width (referred to as “nip width”) and is made to scrub the surface of the photosensitive member at a predetermined relative speed.
While the cleaning roller
303
is made of a magnet in the above description, it may alternatively be a roller that is magnetically biased with the polarity opposite to that of the toner or made of silicon rubber of spongy resin.
Still alternatively, the cleaning roller
303
may be replaced by a brush-shaped member made of a material selected appropriately by taking the hardness of the photosensitive member and the processing speed of the image-forming apparatus into account.
When the brush is used with a photosensitive member showing a high surface hardness such as an a-Si type photosensitive member, it may be a chemical fiber brush made of polyethylene or polystyrene or a brush made of electroconductive fiber obtained by adding carbon to chemical fiber in order to provide the fiber with an desired level of electroconductivity or fiber of amorphous metal (e.g. “
Karaki Tetsuya
Kawada Masaya
Kaya Takaaki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Goodrow John
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