Electrophotography – Image formation – Development
Reexamination Certificate
2000-01-18
2001-06-26
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Development
C399S237000
Reexamination Certificate
active
06253051
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus using electrophotographic technique and relates in particular to an apparatus and method for forming an image using liquid developer composed of toner particles and solvent.
2. Description of the Related Art
There have been proposed wet-type image forming apparatuses having a heating means which is used in the developing process of the electrophotography to improve the quality of image.
In Japanese Patent Application Laid-open No. HEI 5-11566, an image forming apparatus is disclosed which is provided with a preheating roller located downstream from the developing unit and upstream from the transfer unit. The preheating roller is used to vaporize the solvent included in the developed image, which will causes the developed image to be prevented from spreading, resulting in improved quality of image.
However, excess solvent remains in the developed image from the developing unit to the preheating roller. Therefore, the excess solvent is likely to cause the spreading of the developed image, resulting in reduced quality of image. Further, it is necessary to provide space for the preheating roller. Therefore, the structure becomes complicated and its size becomes larger.
In Japanese Patent Application Laid-open No. SHO 58-143362, a squeezing apparatus is disclosed which is provided with a squeezing roller having a heater therein. Heating the squeezing roller to an appropriate temperature causes the viscosity of liquid developer to be reduced, resulting in improved effectiveness of squeeze.
In Japanese Patent Application Laid-open No. HEI 9-101683, a wet-type electrophotographic copying machine is disclosed which is provided with a developing unit having a heating element therein. The heating element heats the liquid developer to an appropriate temperature ranging from 50 to 60 degrees Celsius to prevent the toner particles of the liquid developer from agglomerating.
However, neither the squeezing roller having a heater therein nor the developing unit having a heating element therein as described above provides a means for effectively removing excess solvent from the developed image. Therefore, the excess solvent is likely to cause the spreading of the developed image, resulting in reduced quality of image.
SUMMARY OF THE INVENTION
An object of the present invention, which has been developed in view of the problems of the prior art described above, is to provide a wet-type image forming apparatus and method which allow the quality of image to be improved without increasing in complexity and size.
Another object of the present invention is to provide a wet-type image forming apparatus and method which allow excess solvent to be effectively removed from the developed image.
According to the present invention, a wet-type image forming apparatus for forming an image on a photoconductor member using liquid developer which is composed of toner particles and a solvent, comprises a developing section for developing a latent image on the photoconductor member using the liquid developer stored therein; a squeezing section for squeezing excess solvent from a surface of the photoconductor member; and a heater for heating liquid developer existing on the photoconductor member to a temperature at which the solvent of the liquid developer is prone to vaporize, wherein the heater is provided in one of the developing section and the squeezing section.
According to an aspect of the present invention, a wet-type image forming apparatus for forming an image on a photoconductor member using liquid developer which is composed of toner particles and a solvent, comprises:
a charging section for charging a surface of the photoconductor member;
a latent image forming section for forming a latent image on the photoconductor member;
a developing roller for developing the latent image on the photoconductor member using the liquid developer stored in a reservoir;
a squeezing roller for squeezing excess solvent from the surface of the photoconductor member; and
a heater for heating liquid developer existing on the photoconductor member to a temperature at which the solvent of the liquid developer is prone to vaporize, wherein the heater is provided in one of the developing roller, the reservoir, and the squeezing roller.
According to another aspect of the present invention, a wet-type image forming apparatus for forming an image on a photoconductor belt using liquid developer which is composed of toner particles and a solvent, comprises:
a charging section for charging a surface of the photoconductor belt;
a latent image forming section for forming a latent image on the photoconductor belt;
a developing roller for developing the latent image on the photoconductor belt using the liquid developer stored in a reservoir;
a squeezing roller for squeezing excess solvent from the surface of the photoconductor belt; and
a backup roller opposite to the squeezing roller via the photoconductor belt, for putting a predetermined magnitude of pressure to the squeezing roller and heating liquid developer existing on the photoconductor member to a temperature at which the solvent of the liquid developer is prone to vaporize.
The backup roller may have a heater provided in a hollow thereof such that a periphery of the backup roller is uniformly heated. Alternatively, the backup roller may be made of a material having a predetermined amount of resistance so that the backup roller itself is heated.
The heater heats the liquid developer existing on the photoconductor member to a temperature which is lower than a boiling point of the liquid developer.
The backup roller heats the liquid developer existing on the photoconductor member to a temperature which is lower than a boiling point of the liquid developer.
The heater heats the periphery of the squeezing roller to a temperature which is not lower than a boiling point of the liquid developer.
The backup roller heats a periphery of the squeezing roller to a temperature which is not lower than a boiling point of the liquid developer.
REFERENCES:
patent: 5574547 (1996-11-01), Denton et al.
patent: 5933689 (1999-08-01), Kim
patent: 5940666 (1999-08-01), Han
patent: 5978631 (1999-11-01), Lee
patent: 5987284 (1999-11-01), Lewis
patent: 54-109450 (1979-08-01), None
patent: 58-143362 (1983-08-01), None
patent: 3-270507 (1991-12-01), None
patent: 5-11566 (1993-01-01), None
patent: 6-268696 (1994-09-01), None
patent: 7-311503 (1995-11-01), None
patent: 9-101683 (1997-04-01), None
patent: 9-326837 (1997-12-01), None
patent: 10154994 (1998-06-01), None
patent: 11-38768 (1999-02-01), None
patent: 11-73024 (1999-03-01), None
patent: 11-88205 (1999-03-01), None
patent: 11-308128 (1999-11-01), None
Japanese Office Action issued Oct. 17, 2000 in a related application with English translation of relevant portions.
*Partial translation of Japanese Office Action dated Jul. 12, 2000, explaining relevance of JP11-73024 and JP10-154994.
Hirano Takeshi
Iikura Kazuaki
Chen Sophia S.
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
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