Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
2000-05-11
2001-11-27
Brase, Sandra (Department: 2852)
Electrophotography
Image formation
Photoconductive member
C399S162000, C399S280000, C399S288000, C399S329000
Reexamination Certificate
active
06324366
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sleeve rotation-feed apparatus for feeding a thin film sleeve used in an electrophotographic process of development, transfer, and fixation in an electrophotographic copying machine and an electrophotographic printer, and to a developing apparatus, image formation apparatus, and fixation apparatus using this sleeve rotation-feed apparatus.
2. Description of the Related Art
Conventionally, this type of thin film sleeve feeding apparatus is known, for example, in an electrostatic latent image developing apparatus disclosed in Japanese Patent Publication 1-234869.
FIG. 11
shows configuration of a sleeve feeder in this electrostatic latent image developing apparatus.
This electrostatic latent image developing apparatus includes: a drive roller
110
for rotation, a cylindrical thin film member (thin film sleeve)
111
having a circumferential length slightly greater than that of the drive roller
110
, a guide member
109
for pressing the thin film member
111
against the drive roller
110
, a layer thickness regulating member
112
in pressed contact with the outer surface of the thin film member
111
, and the like.
The guide member
109
has an arc-shaped inner surface corresponding to the outer shape of the drive roller
110
. Accordingly, this guide member
109
brings the thin film member
111
into contact with the circumference of the drive roller
110
, so that a sag of the thin film member
111
is concentrated to an open portion provided against a photosensitive drum
100
of the guide number
109
and a predetermined space S is formed between the drive roller
110
and the thin film member
111
. Thus, toner supplied by the layer thickness regulating member
112
to the outer surface of the thin film member
111
is supplied to the outer surface of the photosensitive drum
100
for development of an electrostatic latent image.
Here, assuming &mgr;1 as a friction coefficient between the outer circumference of the drive roller
110
and the inner circumference of the thin film member
111
and &mgr;2 as a friction coefficient between the outer circumference of the thin film member
111
and the guide member
109
, the relationship &mgr;1>>&mgr;2 is satisfied. When the drive roller
110
rotates in the direction of the arrow b, the thin film member
111
is also fed in the same direction.
Apart from the aforementioned electrostatic latent image developing apparatus, there is known a sleeve rotation-feed apparatus having the identical configuration used as a photosensitive belt feed apparatus.
That is, in this photosensitive belt feed apparatus, a thin film having a photosensitive function or the like is painted or formed by deposition on a thin film member (thin film sleeve) constituting a photosensitive belt base. A drive roller is arranged inside the loop of this photosensitive belt and a guide member is arranged outside the loop, so that the photosensitive belt is fed in the same way as the configuration shown in FIG.
11
.
However, in the aforementioned conventional sleeve rotation-feed apparatus, the respective member materials should be selected so as to satisfy the relationship of friction coefficients as &mgr;1>>&mgr;2. This reduces flexibility of the design and causes a disadvantage in reducing the cost.
Moreover, since the thin film member
111
is pressed by the guide member
109
or the like against the drive roller
110
, scratches may be caused on the outer circumference of the thin film member
111
which is in contact with the guide member
109
.
Especially, in the aforementioned photosensitive belt in the feed apparatus, a scratch grows as the operation time increases, resulting in a short service life of the apparatus.
In order to prevent generation of such a scratch, a soft cloth piece may be used to a portion where the guide member is in contact with the thin film member. However, the effect is considered to be small.
Moreover, in the aforementioned conventional apparatus, dusts and toner come into the portion between the thin film member and the drive roller. This lowers the friction force and the sleeve rotation becomes unstable, causing a defective image. On the other hand, in order to rotate at a high speed while suppressing generation of speed irregularities, it is necessary to increase the friction force between the drive roller and the thin film member. For this, the thin film member should be pressed to the drive roller with a greater force. This makes greater the problem of scratch generation on the thin film member. In the conventional apparatus, this has been an obstacle in obtaining a high-speed rotation.
Moreover, when the friction force is increased, the drive torque of the drive roller is increased, increasing the motor size, disabling energy saving.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a sleeve rotation-feed apparatus capable of feeding a thin film sleeve without using a friction force of a drive roller as well as a developing apparatus, an image formation apparatus, and fixation apparatus using this sleeve rotation-feed apparatus.
In order to achieve the aforementioned object, the sleeve rotation-feed apparatus according to the present invention uses a drive roller for feeding a cylindrical thin film sleeve arranged around the drive roller, the apparatus comprising: a drive roller in which at least roller surface has electro-conductivity and a dielectric layer is formed on the conductive roller surface; an electric charger for charging the roller surface of the drive roller; a power source for applying a potential difference between the conductive roller surface of the drive roller and the electric charger; a separator arranged in the proximity of the drive roller for separating the thin film sleeve from the drive roller; and a cylindrical thin film sleeve arranged so as to surround the drive roller, the electric charger, and the separator in such a manner that a portion of the sleeve is in contact with the drive roller, wherein the dielectric layer of the drive roller is used to absorb a portion of the thin film sleeve to a portion of the roller surface, so as to be fed.
In the sleeve rotation-feed apparatus having the aforementioned configuration, an electrostatic absorption force obtained by charging of the dielectric layer of the drive roller is used to absorb a portion of the thin film sleeve to a portion of the roller surface, thus feeding the thin film sleeve. The thin film sleeve is separated from the drive roller by separator arranged at a necessary position, so that the thin film sleeve performs various processes.
Thus, it is possible to feed the thin film sleeve without using a friction force of the drive roller. This enables to eliminate scratches on the thin film sleeve which may be caused by the friction. The material of the drive roller can be selected without considering the friction coefficient.
According to another aspect of the present invention, the sleeve rotation-feed apparatus using a drive roller for feeding a cylindrical thin film sleeve arranged around the drive roller comprises: a drive roller having a roller surface formed by a material of a high resistance and a plurality of linear electrodes extending in axial direction of the roller and arranged in a circumferential direction, wherein every other electrodes constitute an electrode block electrically connected, thus obtaining two of the electric blocks; a power source for applying a potential difference between the two electrode blocks; a separator arranged in the proximity of the drive roller for separating the thin film sleeve from the drive roller; and a cylindrical thin film sleeve arranged so as to surround the drive roller and the separator in such a manner that a portion of the sleeve is in contact with the drive roller, wherein the electrode blocks of the drive roller are used to absorb a portion of the thin film sleeve to a portion of the roller surface, so as to be fed.
In the sleeve rotation-f
Funayama Yasuhiro
Uezono Tsutomu
Brase Sandra
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
LandOfFree
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