Electrophotography – Image formation – Development
Reexamination Certificate
2002-03-11
2003-11-18
Pendegrass, Joan (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06650857
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-74539, filed on Mar. 15, 2001; the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus which forms developed images using liquid developers containing toner particles and a carrier liquid and more particularly to an image forming apparatus which is capable of removing excess carrier liquid remaining on developed images.
2. Description of the Related Art
An image forming apparatus to get developed image s using liquid developers has such merits that high image quality is realized as extremely fine toner particles in sub micron size are used, it is economical as sufficient image density is provided by small amount of toners and in addition, texture as excellent as printing (for example, offset printing) is obtained and energy saving is achieved as toners can be fixed on paper at relatively low temperatures.
When forming an image by this image forming apparatus using liquid developers, as one method to transfer developed images formed on a photosensitive drum, there is a pressure transfer method which transfers toner particles on the surface of the photosensitive drum to a recording medium utilizing adhesive power of toner particles by bringing the photosensitive drum in contact with the recording medium under pressure.
This pressure transfer method is a method to transfer toner particles on the surface of the photosensitive drum onto a recording medium utilizing adhesive power of toner particles by bringing the photosensitive drum in contact with the recording medium under pressure. In this pressure transfer method, transfer efficiency is lowered if the photosensitive drum surface is wet by carrier liquid at the time of transfer and it is therefore necessary to thoroughly remove excess carrier liquid remaining on a developed image before starting the transfer process in order to improve transfer efficiency.
As a device to remove excess carrier liquid remaining on a developed image prior to the transfer process, a device to dry and remove excess carrier liquid remaining on the photosensitive drum after completing the development using at least more than one blower was so far developed. Further, for removing excess carrier liquid on a developed image prior to the transfer process, a device for absorbing and removing excess carrier liquid remained on a photosensitive drum using an elastic porous roller after completing the development was developed as disclosed in Japanese Patent Publication Numbers 11-249445, 11-249524 and 9-15981.
Further, as a device for removing excess carrier liquid remaining on a developed image prior to the transfer process, a device for absorbing and removing excess carrier liquid remained on a photosensitive drum after completing the development using an elastic roller and then, for further drying and removing excess carrier using a blower was proposed so as to increase excess carrier liquid removing efficiency as disclosed in Japanese Patent Publication No. 58-66953.
However, reduction of a time required for removing excess carrier liquid was increasingly demanded with the progress of the high-speed image forming process in recent years and in the case of such a high-speed image forming apparatus, even when a method for absorbing and removing excess carrier liquid by an elastic porous roller was used jointly with a method for drying and removing excess carrier liquid by a blower as mentioned above, excess carrier liquid could not be removed thoroughly before a developed image reached the transfer position after completing the development and transfer efficiency according to the pressure transfer method might possibly be lowered.
Further, in the case of a transfer device according to the pressure transfer method, with the progress of a high-speed image forming apparatus, pressure force at the transfer position increases. With this increase in pressure force, deterioration of transfer efficiency for residual excess carrier liquid became further remarkable and transfer efficiency was remarkably impeded and display quality might be lowered extremely.
Accordingly, irrespective of the progress of an image forming process, it is desired to realize a practical use of a high-speed image forming apparatus that enables more efficient pressure transfer and improves display quality by thoroughly removing excess carrier liquid prior to the transferring operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high-speed image forming apparatus, which is provided with a blowing unit for removing excess carrier liquid remaining on a photosensitive drum quickly and certainly prior to transferring an image, improves transfer efficiency according to a pressure transfer method and obtains a transferred image of high quality.
According to the embodiments of the present invention, an image forming apparatus comprises: a latent image forming unit for forming an electrostatic latent image on the surface; a developing device which supplies liquid developer containing toner particles and carrier liquid to the electrostatic latent image, and forms a developed image on the latent image forming unit; a transferring device which transfers the developed image on the latent image forming unit onto a recording medium, a conveying path of the developed image being formed from the developing device to the recording medium; and a blowing unit equipped with a guide wall to cover at least a part of the conveying path, the guide wall providing a gap of more than 0.5 mm and less than 5 mm, and an air current generating source which generates an air current in the gap.
Further, according to the embodiments of the present invention, the image forming apparatus comprises: a photosensitive drum for forming an electrostatic latent image on the photosensitive drum surface; a developing device which supplies liquid developer containing toner particles and carrier liquid to the electrostatic latent image, and forms a developed image on the photosensitive drum; a transferring device which transfers the developed image on the photosensitive drum onto a recording medium, a conveying path of the developed image being formed from the developing device to the recording medium; and a nozzle block equipped with a guide wall to cover at least a part of the conveying path, the guide wall providing a gap of more than 0.5 mm and less than 5 mm, and an air current generating source which generates an air current in the gap.
REFERENCES:
patent: 5221944 (1993-06-01), Yoda et al.
patent: 2002/0028090 (2002-03-01), Shin et al.
patent: 10-10874 (1998-01-01), None
Iida Atsuko
Nukada Hideki
Sasaki Takashi
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