Electrophotography – Image formation – Development
Reexamination Certificate
2000-04-06
2001-04-17
Lee, Susan S. Y. (Department: 2852)
Electrophotography
Image formation
Development
C399S348000, C399S352000
Reexamination Certificate
active
06219512
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner image dryer applied to a wet electrophotographic recording system such as a copying machine and a printer using a liquid developing process, for selectively absorbing only liquid carriers from a development liquid for adjusting transfer conditions.
2. Description of the Related Art
A conventional image printer using wet electrophotographic recording system, has an photosensitive belt (photosensitive body) formed with a photosensitive material, a charger for charging the photosensitive belt, optical exposing unit for forming an electrostatic image on the charged photosensitive belt, development device for forming a toner image by using a development liquid, and transfer and fixing device for transferring the toner image to a recording medium and fixing thereon. Usually, the development liquid used in the development device mainly has toners and liquid carriers for charging toners so as to selectively develop toner grains and dispersing the toners in the development liquid.
In the conventional image printer of this type, it is necessary to selectively absorb the liquid carriers after developing a toner image on photosensitive belt with the development liquid and before transferring the image onto the recording medium. This is because the toner image is set in a filmed state to have a solid component ratio of not less than 95% to thereby adjust transfer conditions.
For absorbing the liquid carriers from the development liquid, a toner image dryer is used in the image printer. Usually, the toner image dryer is provided by a heat roller which contacts on the photosensitive body. The heat roller absorbs the liquid carriers from the photosensitive belt formed with the toner image, and vaporizes from the liquid carriers by heating the roller and diffusing to set in a filmed state to have a solid component ratio of not less than 95%.
But, it is difficult to maintain a balance between absorption and diffusion/vaporization at not more than the heat resisting temperature of the photosensitive belt.
Furthermore, in the conventional roller type drier, image picking due to shearing force at an absorbing and contact part (NIP part) progresses and so does ink contamination in the image drying system accordingly, with the result that it becomes difficult to realize an intended service life.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a toner image drier capable of obtaining a good image by preventing an image drying defect derived from ink contamination, and ensuring a lengthened service life.
According to the present invention, a toner image dryer for a wet electrophotographic recording system for forming a toner image on a photosensitive body by a liquid development, has a drying belt having a functional material coated on a film surface of a base material; a pressure-contact roller which contacts with the drying belt to cause the drying belt to be contacted on the photosensitive body and rotates with the photosensitive body; a heat roller for heating the drying belt; and tension application member for applying predetermined tension to said drying belt. And the drying belt is rotated and moved to be thereby heated by the heat roller, and the drying belt absorbs and vaporizes solvent from the photosensitive.
In this case, a cleaning mechanism for recovering ink adhering to the drying belt from the photosensitive body may be provided. Also, rubber beads may be provided on the back surface of the drying belt.
Further, the tension application means may be either an independent roller or integral with a heat roller.
The drying belt is, most preferably, made of a PET (polyethylene terephthalate) base material.
According to such a toner image dryer, even if the vaporization temperature of the heat roller is set higher, it is possible to suppress the surface temperature of the pressure-contact roller low and, therefore, to accelerate the recovery of steam while preventing image picking caused by the pressure-contact roller.
REFERENCES:
patent: 3510903 (1970-05-01), Stoever et al.
patent: 5911101 (1999-06-01), Park
patent: 6064851 (2000-05-01), Saitoh
patent: 54-131940 (1979-10-01), None
patent: 57-32472 (1982-02-01), None
patent: 62-32484 (1987-02-01), None
patent: 6-75510 (1994-03-01), None
patent: 9-244495 (1997-09-01), None
patent: 11-73024 (1999-03-01), None
Lee Susan S. Y.
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
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