Electrophotography – Image formation – Development
Reexamination Certificate
2000-08-29
2002-05-07
Braun, Fred L. (Department: 2852)
Electrophotography
Image formation
Development
C399S238000, C399S249000
Reexamination Certificate
active
06385421
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-266950, filed Sep. 21, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and particularly to an image forming apparatus which forms an image by a wet developing method with use of a liquid developer in which toner is dispersed in a solvent.
An image forming apparatus using a liquid developer attracts attention again as a technique which matches with high speed and high image quality and can provide an image with high image quality owing to toner of fine grains. This apparatus is excellent in gradient reproductivity and can provide an image equal to printing. The softening point of the toner is low and an advantage is obtained in that images can be easily fixed. However, since the developer is a liquid composed of toner grains and a carrier liquid, further improvements are required for the supply method thereof and the method of removing an excessive developing liquid (carrier liquid) remaining on a photosensitive member. In the present situation, a satisfactory image forming apparatus has not yet been obtained with respect to the developing device, transfer device, and cleaning devices for respective parts.
U.S. Pat. No. 5,576,815 discloses a wet electrophotographic color image forming apparatus.
FIG. 11
is a view schematically showing the wet electrophotographic color image forming apparatus described in an embodiment of the above-mentioned patent.
In the patent according to the invention in the patent, there is a description that the image forming apparatus includes “a plurality of developing sections
12
,
14
,
16
, and
18
arranged along a route of a photosensitive member, and in
FIG. 11
, the system
10
is constructed so that a multi-color image can be formed by one single path of a photosensitive member
20
provided therein. If this kind of single bus system
10
is adopted, a multi-color image can be formed at a very high speed.”
Also, the patent describes that “the image forming apparatus according to the above-described invention can be applied to a single-color liquid developing system and a multi-color/multi-path liquid developing system, although the image system
10
is shown as a multi-color/single-path step in FIG.
11
.”
Further, there is a description saying the “applicability to a system in which the photosensitive member is a belt, drum, or sheet-like one”. However, the embodiment only shows a belt-like photosensitive member but does not at all describe merits obtained in case where the photosensitive member has a drum-like shape. It does not describe originality or inventivity which should be required because the photosensitive member is a drum-like member, or improvements thereof. Thus, the patent merely suggests possibility of a drum-like photosensitive member.
Actually, in case of a drum-like photosensitive member, further originality, inventivity, and improvements are required.
On the other hand, the present invention provides a wet electrophotographic color image forming apparatus which realizes a multi-color/single-path step in case of using a drum-like photosensitive member (including a drum with a sheet wound thereon) and provides a wet electrophotographic color image forming apparatus which overcomes all the conventional problems.
BRIEF SUMMARY OF THE INVENTION
The present invention has an object of providing a color image forming apparatus according a liquid developing method and a developing liquid supply unit, which uses a drum-like photosensitive member and are capable of forming multi-color images at a high speed.
The present invention has been made on the basis of the problems described above and provides a developing liquid supply unit which has a casing for containing a developing liquid and is detachably attached to an image forming apparatus, comprising: a driven member for receiving a drive force from outside; a discharging section for discharging the developing liquid from the casing to the outside; a receiving section for receiving the developing liquid from the outside into the casing; and a developing liquid transfer mechanism for supplying the developing liquid in the casing, to a developing device in the image forming apparatus, through the discharging section, based on the drive force to the driven section, and for further returning the developing liquid from the developing device into the casing through the receiving section, in a situation that the developing liquid transfer mechanism is attached to the image forming apparatus.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image; a removing device for removing an excessive portion of the developing liquid supplied by the developing device, the excessive portion of the developing liquid remaining on the photosensitive member after development; and a returning mechanism for returning the excessive portion of the developing liquid, which is removed by the removing device, into a casing of a developing liquid supply unit for supplying the developing liquid to the developing device.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming devices provided along an arc-like surface of a photosensitive member, for forming an electrostatic latent image on the surface of the photosensitive member; and a plurality of developing mechanisms for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image, wherein the latent image forming devices includes a plurality of light sources each has a laser device, a single deflection device for deflecting a plurality of beams respectively generated from the laser sources, and an imaging lens for providing the plurality of beams deflected by the deflection device with a predetermined characteristic, thereby to form an image on the photosensitive member.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming devices provided along an arc-like surface of a photosensitive member, for forming an electrostatic latent image on the surface of the photosensitive member; a plurality of developing mechanisms provided along the arc-like surface of the photosensitive member, for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image; and a plurality of hold member for holding the developing mechanisms such that lowermost parts of developing rollers, levels of the developing liquid, and end parts of openings are arranged in this order from a lower side in a gravitational direction, respectively.
Also, the present invention provides an image forming apparatus comprising: a plurality of charging device provided along an arc-like surface of a photosensitive member, for charging the surface of the photosensitive member; a plurality of latent image forming mechanisms for forming electrostatic latent images on the surface of the photosensitive member charged by the charging device, respectively; and a plurality of developing devices for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent images are formed by the latent image forming mechanisms, thereby to develop the latent images, respectively.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming mechanisms provided along an arc-like surface
Imamiya Koji
Yamaguchi Yuka
Braun Fred L.
Foley & Lardner
Toshiba Tec Kabushiki Kaisha
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