Electrophotography – Image formation – Development
Reexamination Certificate
2001-10-25
2003-03-25
Braun, Fred L. (Department: 2852)
Electrophotography
Image formation
Development
C399S302000, C430S117200
Reexamination Certificate
active
06539191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This patent specification relates generally to a method for forming electrophotographic images, and more specifically to the method for forming color toner images on a photosensitive member using a plurality of liquid developers.
2. Discussion of the Background
In the liquid development process for forming electrophotographic color images, toner particles in liquid developers are designed in general to have a ratio of pigment to resin fewer than that of dry developers. With these particles undue pile height of toner layers can be alleviated and the image quality is improved. In addition, the particle size is relatively small and adhesion between the particles is generally weak.
As a result, in the process of image fixing by means of heated rolls and plates the rocking mechanism of the toner onto copy sheets is therefore less operative, thereby leading to relatively poor image fixing characteristics.
Further, although the use of non-volatile silicone oil is examined as a carrier from the safety and environmental concern, a considerable decrease in fixing efficiency has been found possibly caused by the releasing characteristics of the silicone oil.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present disclosure to provide a novel and improved liquid development method and system for forming electrophotographic color images, having most, if not all, of the advantages and features of similar employed methods, while eliminating many of their disadvantages.
It is another object of the present disclosure to provide a novel method and system for forming electrophotographic color images capable of achieving sufficient image fixing efficiency, while retaining uniformity in color images by forming a layer of transparent toner on top of a plurality of underlying color toner layers formed beforehand. In addition, sufficient image fixing capability and appropriate glossiness can be achieved with the present method and system even with the use of silicone oil as a carrier, which has high releasing characteristics.
The following brief description is a synopsis of only selected features and attributes of the present disclosure. A more complete description thereof is found below in the section entitled “Description of the Preferred Embodiments”.
A method is disclosed herein for forming electrophotographic images by way of forming toner images on a photosensitive member using a plurality of liquid developers containing color particles, and subsequently transferring the toner images to a recording medium, e.g. a sheet of paper. This method includes the step of affixing transparent toner particle containing developer at least onto the portions of the toner images on the photosensitive member prior to transferring the toner images. A system implementing that method is also disclosed.
The transparent toner used can have a particle size larger than that of the color particles, and the content of solid materials in the transparent toner containing developer can be larger than that in the color particle containing developer.
In another aspect, a method and system disclosed herein is for forming electrophotographic images by forming toner images on a photosensitive member using a plurality of color particle containing liquid developers, and subsequently transferring the toner images to a recording medium, e.g. a sheet of paper, in which the color particles are charged to a first polarity.
The present method includes the step of affixing, in addition to the plurality of color particle containing liquid developers, transparent toner particle containing developers at least onto the portions of the toner images on the photosensitive member prior to transferring the toner images. The transparent toner particles in the developer are charged to a second polarity that is either the same as, or opposite to, the first polarity. A system implementing that method is also disclosed.
The transparent toner used in this method can be formed such that the content of solid materials in the developer is generally larger than that in the color particle containing developer. In addition, the developer can consist essentially of carriers which contain ultraviolet curing resin to be image fixed through ultraviolet beam irradiation, and non-contact heating steps of the toner images are preferably carried out prior to the image fixing through ultraviolet beam irradiation.
Further, the liquid developers can consist as the carrier essentially of silicone oil composition which is nonvolatile at room temperature.
REFERENCES:
patent: 5176974 (1993-01-01), Till et al.
patent: 5612777 (1997-03-01), Malhotra
patent: 5915144 (1999-06-01), Ide et al.
patent: 6397030 (2002-05-01), Watanabe
patent: 3-144668 (1991-06-01), None
patent: 4-365061 (1992-12-01), None
patent: 2000-56575 (2000-02-01), None
Braun Fred L.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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