Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-02-23
2001-06-05
Martin, Roland (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S111400, C430S124300, C399S320000
Reexamination Certificate
active
06242148
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic apparatus or a static recording apparatus, a method for forming images using this apparatus, and a developing agent for use in this apparatus.
An electrophotographic apparatus or a static recording apparatus forms an image by using a photoreceptor or a derivative to form an electrostatic latent image on an image carrier, using a toner to develop and visualize the electrostatic latent image, transferring the obtained toner image to an image receiving member, and then fixing the image. Conventionally known fixing techniques include the heating fixing method, the pressure fixing method, the high-frequency heat fixing method, the electromagnetic induction heating method, and the combined fixing method that is a combination of the flush fixing method and the electromagnetic induction heating method.
In particular, the electromagnetic induction heating method is known as a technique capable of reducing the size of the apparatus, the warm-up time, and the amount of energy required. This technique installs an exciting coil in pressure means and carries out heating using, as a heat source, Joule heat generated by applying high-frequency magnetic fields to a magnetized metallic surface of heating means provided opposite to the pressure means.
The electromagnetic induction heating method, however, is disadvantageous in that the temperature distribution on the surface of the heating means may not be uniform. For example, a phenomenon may occur in which part of the heating means surface which corresponds to a width-wise central portion of the image receiving member is hot, while parts of the heating means surface which correspond to opposite ends thereof are cool. In this case, images of a stable image density cannot be obtained. In addition, parts of the heating means surface by which the image receiving member has passed may is cooled because the heat transfers to the material, while parts thereof by which the material has not passed become hotter than required, resulting in offsets in the end portion of the material.
BRIEF SUMMARY OF THE INVENTION
The present invention is provided in view of the above conventional problem, and it is a first object thereof to provide a developing agent that serves to reduce the size of the apparatus, the warm-up time, and the amount of energy required and that provides excellent images of a stable image density without an offset when applied to a heating means that is likely to cause a non-uniform temperature.
In addition, it is a second object of the present invention to provide a small image forming apparatus that reduces the warm-up time and the amount of energy required and that provides excellent images of a stable image density without an offset.
Further, it is a third object of the present invention to provide an image forming method that can reduce the size of the apparatus used, the warm-up time, and the amount of energy required and that provides excellent images of a stable image density without an offset.
First, the present invention provides a developing agent comprising:
a coloring agent and
a toner containing a styrene-acrylic resin having a glass transition point between 50 and 65° C. and a 150° C. melt index between 1 and 10 (g/10 min.);
a polyethylene wax in 1 to 3% by weight. of the total weight of the toner, the polyethylene wax having a melting point between 90 and 128° C.; and
a polypropylene wax in 3 to 6% by weight. of the total weight of the toner, the polypropylene wax having a melting point between 135 and 146° C.
Second, the present invention provides an image forming apparatus comprising:
an image carrier;
a developing device provided opposite to the image carrier for housing a developing agent comprising:
a coloring agent and a toner containing a styrene-acrylic resin having a glass transition point between 50 and 65° C. and a 150° C. melt index between 1 and 10 (g/10 min.),
a polyethylene wax in 1 to 3% by weight. of the total weight of the toner, the polyethylene wax having a melting point between 90 and 128° C., and
a polypropylene wax in 3 to 6% by weight. of the total weight of the toner, the polypropylene wax having a melting point between 135 and 146° C., and for developing an electrostatic latent image formed on the image carrier in order to form a developing agent image;
a transfer device for transferring the developing agent image onto an image receiving member; and
a fixing device based on the electromagnetic induction heating method for fixing the developing agent image transferred onto the image receiving member.
Third, the present invention provides an image forming method comprising:
the electrostatic latent image formation step of forming an electrostatic latent image on an image carrier;
the developing step of developing the electrostatic latent image using a developing agent comprising a coloring agent and a toner containing a styrene-acrylic resin having a glass transition point between 50 and 65° C. and a 150° C. melt index between 1 and 10 (g/10 min.),
a polyethylene wax in 1 to 3% by weight. of the total weight of the toner, the polyethylene wax having a melting point between 90 and 128° C., and
a polypropylene wax in 3 to 6% by weight. of the total weight of the toner, the polypropylene wax having a melting point between 135 and 146° C.;
the transfer step of transferring the developed developing agent image onto an image receiving member; and
the fixing step of fixing the developing agent image transferred onto the image receiving member, by heating the image based on the electromagnetic induction heating method while pressurizing the image.
According to the present invention, the non-uniform temperature distribution on the surface of the heating member, which is a disadvantage of the electromagnetic induction heating method, can be avoided by combining the styrene-acrylic resin of a high viscosity with the polyethylene and polypropylene waxes of low melting points to widen a non-offset area.
REFERENCES:
patent: 5176978 (1993-01-01), Kumashiro et al.
patent: 5612160 (1997-03-01), Inoue et al.
patent: 5814428 (1998-09-01), Kido et al.
patent: 5824446 (1998-10-01), Nishihara et al.
patent: 5866291 (1999-02-01), Ikegami et al.
patent: 5948583 (1999-09-01), Silence et al.
patent: 1-134385 (1989-05-01), None
patent: 7-181821 (1995-07-01), None
Foley & Lardner
Martin Roland
Toshiba Tec Kabushiki Kaisha
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