Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-02-23
2003-11-18
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S110400, C430S111400, C430S125320
Reexamination Certificate
active
06649315
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a developing method comprising cleaning off a developer remaining on a photosensitive member by a developing device at the same time as development in an image forming apparatus such as an electrophotographic apparatus making good use of electrophotography or an electrostatic recording apparatus, and a non-magnetic one-component developer used in this developing method.
BACKGROUND ART
An image forming apparatus according to electrophotography is generally equipped with a photosensitive member (electrostatic latent image-bearing member), a means for evenly and uniformly charging the surface of the photosensitive member, an exposing means (electrostatic latent image-forming means) for writing an electrostatic latent image on the charged surface of the photosensitive body, such as a laser device, a developing means for developing the electrostatic latent image on the photosensitive member with a developer (toner), a transferring means for transferring the developer image developed to a transfer medium such as transfer paper or an OHP sheet, and a fixing means for fixing the toner image transferred on the transfer medium. Many of such conventional image forming apparatus are also equipped with a cleaning device for removing the developer remaining on the photosensitive member.
Specifically, for example, such an image forming apparatus equipped with a cleaning device as illustrated in
FIG. 2
is generally used. The image forming apparatus has a structure that a cleaning device
202
, a charging device
203
, an exposing device
204
, a developing device
205
, a transferring device
206
, etc. are arranged around a photosensitive member
201
. In order to form an image with the image forming apparatus, the surface of the photosensitive member
201
is first evenly and uniformly charged to a plus (+) or minus (−) charge by the charging device
203
. The charging device illustrated in
FIG. 2
is a charger according to corona discharge. Image exposure is then conducted by the exposing device
204
to form an electrostatic latent image on the photosensitive member
201
. Electric resistance is lowered at an area (exposed region) of the photosensitive member, to which light has been applied by the exposure, and so the plus or minus charge vanishes.
The electrostatic latent image formed on the photosensitive member
201
is developed by the developing device
205
. The developing device
205
illustrated in
FIG. 2
is constructed by a developing roller
208
, a layer-thickness regulating blade
209
for developer, a developer (toner)
210
, a developer feed roller
212
, a casing
211
for containing these members therein, etc. The layer thickness of the developer transferred to the developing roller
208
by the rotation (rotating direction C) of the feed roller
212
is controlled by the blade
209
coming into contact with the developing roller
208
, whereby a thin layer of the developer is formed on the developing roller
208
. The developer on the developing roller
208
is applied to the electrostatic latent image by bringing the developing roller
208
(rotating direction B) and the photosensitive member
201
(rotating direction A), which rotate to reverse directions to each other, into contact with each other, thereby forming a developer image on the photosensitive member
201
.
In the case of ordinary normal development system, a charge remains only on image portions such as characters corresponding to original due to image exposure. A developer charged to a polarity opposite to the charge of this electrostatic latent image is applied to form the developer image. The developer image on the photosensitive member
201
is electrostatically transferred to a transfer medium
207
by the transferring means
206
. The transferring device illustrated in
FIG. 2
is a charger according to corona discharge and serves to charge the transfer medium
207
to a polarity opposite to the developer to transfer the developer image from the surface of the photosensitive member to the transfer medium. The developer image transferred to the transfer medium
207
is fixed to the transfer medium by any of various methods such as heating, pressing and use of solvent vapor.
In the transferring step, a part of the developer. remains on the photosensitive member
201
without being transferred to the transfer medium
207
. Therefore, this kind of image forming apparatus is generally equipped with a cleaning device
202
for removing the developer remaining on the photosensitive member
201
. After the transferring step, the developer remaining on the photosensitive member
201
is removed by a cleaning blade
202
a
of the cleaning device
202
and accumulated. in the cleaning device
202
.
Such an image forming apparatus has involved such problems that (1) the developer accumulated in the cleaning device must be disposed, and so maintenance is complicated, (2) pollution about the image forming apparatus and of environment is incurred by flying of the developer, (3) the photosensitive member is abraded or damaged by its contact with the cleaning blade, and so image quality is deteriorated as the number of printed sheets increases, (4) the developer ground by the contact with the cleaning blade adheres to the photosensitive. member to tend to cause toner filming,.and (5) the degree of freedom of design in the image forming apparatus is lowered by the provision of the cleaning device, thereby interfering with the miniaturization of the image forming apparatus.
In order to solve such problems as described above, there have therefore been proposed developing methods (cleaning systems concurrent with development) that a one-component developer is used to recover the developer remaining on a photosensitive member by a developing device at the same time-as development (Japanese Patent Application Laid-Open Nos. 203182/1987and 7972/1991). When such a cleaning system concurrent with development is adopted, there is no need to provide a cleaning device equipped with a cleaning blade. As described above, the surface of the photosensitive member is evenly and uniformly charged to a plus (+) or minus (−) charge. In the cleaning system concurrent with development, a developing roller carrying the developer charged to the same polarity as the charged polarity of the photosensitive member is arranged in opposition to the photosensitive member, and an exposed region on the photosensitive member, which has been charged, is developed with the developer, and at the same time the remaining developer adhered to a non-exposed region on the photosensitive member is removed by suction on the side of the developing roller to conduct cleaning.
FIG. 1
illustrates an exemplary image forming apparatus for carrying out such a developing system. The details of the image forming apparatus illustrated in
FIG. 1
will be described subsequently. Here, the principle of the cleaning system concurrent with development is described with reference to FIG.
1
and FIG.
3
. As illustrated in FIG.
3
(A), the surface of a photosensitive member
1
is first evenly and uniformly charged to, for example, a plus charge by means of a charging device
3
(for example, charging roller). Image exposure is then conducted by a exposing device
4
to form an electrostatic latent image on the photosensitive member
1
. As illustrated in FIG.
3
(B), the charge vanishes at an exposed region
302
on the photosensitive member due to photoconductivity, and so the surface potential thereof is lowered. The plus (+) charge remains at a non-exposed region
301
. As illustrated in FIG.
3
(C), a thin layer
10
a
of a developer (toner) charged to a plus (+) charge is formed on the surface of a developing roller
8
.
The surface potential of the non-exposed region
301
and the surface potential of the exposed region
302
on the photosensitive member
1
are regarded as Vo and Vq, respectively. The development bias voltage applied to the developing roller
8
is regarded as Vb,
Dinsmore & Shohl LLP
Goodrow John
Nippon Zeon Co. Ltd.
LandOfFree
Nonmagnetic one component developer and developing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nonmagnetic one component developer and developing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonmagnetic one component developer and developing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3131051