Electric heating – Heating devices – Combined with diverse-type art device
Reexamination Certificate
1996-08-14
2001-12-11
Heinrich, Samuel M. (Department: 1725)
Electric heating
Heating devices
Combined with diverse-type art device
C219S469000, C219S549000
Reexamination Certificate
active
06329639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat generating medium for toner image fixing, which is used for heating and fixing a toner image in an image forming apparatus, such as a copying machine or a printer, and a fixing apparatus using the heat generating medium.
2. Discussion of the Prior Art
A known heating/fixing apparatus for an image forming apparatus includes a heating roll, and a pressure roll coming in press contact with the heating roll. The heating roll is constructed such that the surface of a pipe-like metal roll is covered with fluoroplastics or silicon rubber, and a bar-like heater lamp is inserted into the hole longitudinally formed in the metal roll. Current is fed to the heater lamp which in turn radiates heat. The metal roll absorbs the radiant heat through the inner wall thereof, to increase temperature of the whole heating roll up to the temperature required for toner image fixing. A recording sheet bearing a non-fixed toner image recorded thereon is moved through a nip between the heating roll and the pressure roll. At this time, the non-fixed toner image undergoes heating and pressure to be fixed on the recording sheet. For the heating/fixing apparatus, reference is made to Japanese Patent Publication Nos. Sho. 59-21557, 58-36337, and 56-7236.
In the heating/fixing apparatus thus constructed, it is necessary to heat the whole metal heating roll up to the temperature required for toner image fixing, and to keep the roll at that temperature. For this reason, the fixing apparatus suffers from the following problems. The power consumption is large. A quantity of generated heat is large, increasing temperature within the apparatus. Much time is required for heating the metal heating roll up to the fixing temperature since the heating roll has a large heat capacity. It is difficult to strictly control toner temperature during the fixing process. This fact leads to deterioration of the image quality.
The inventors of the Present Patent Application proposed a unique image fixing apparatus in Published Unexamined Japanese Patent Application No. Hei. 4-114184. The image fixing apparatus includes heating means for heating a non-fixed image in a manner that it presses an image bearing means bearing a non-fixed image thereon from above, and control means which receives image signals from a record head for forming a non-fixed image, and controls the heating means so as to selectively heat only an area including the non-fixed image on a sheet in accordance with the image signals. The heating means, shaped like a belt or a rigid-drum, is composed of a layer for preventing color image forming material of a non-fixed image from sticking to the heating means, a conductive layer layered on the material sticking preventing layer, and a heating layer, layered on the conductive layer, for generating heat when it receives electric energy. The heating means presses the image bearing means bearing a non-fixed image thereon from above, and heat the non-fixed image. The image fixing apparatus succeeds to some extent in reducing the power consumption, realizing the quick start of the apparatus, increasing the fixing speed, checking the increase of the temperature within the apparatus, and the like.
In the proposed fixing apparatus, the image signals for fixing the non-fixed toner image are input to the heating means through the record head. The record head consists of a plural number of blocks longitudinally arrayed, and is supported so as to directly contact with the heating means in a sliding manner. In fixing the image, the blocks are selectively heated in accordance with image signals. In some friction conditions, all the longitudinally arrayed blocks are not always placed in a stable heating state. Since the heating means is thin, its transportation reliability is frequently poor, Particularly, in the case of the belt-like heat generating medium, the transportation reliability becomes problematic since a tensile strength thereof is small. The small tonsils strength also brings about poor contact of the heating means with the image bearing means and insufficient pressure.
The inventors intently and carefully made a study for developing an inventive and unique image fixing apparatus which is more compact, more reliably transported, and can solve the various problems of the conventional fixing apparatus, including undesirable power consumption, unstable, temperature within the apparatus, large heat capacity of the heating roll requiring start-up delay, and insufficient temperature control accompanied by deterioration of image quality.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a heat generating medium for image fixing which is simple in construction, highly reliable in transportation, short in stand-by time, easy in temperature control, and applicable for various types of the fixing apparatus, and further consumes less power and checks temperature within the apparatus.
Another object of the present invention is to provide a fixing apparatus using such a heat generating medium, which is useful when it is used in electrophotographic copying machines, printers, facsimile machines, and the like.
To achieve the first object, there is provided a heat generating medium for image fixing comprising a conductive support layer of good thermal conduction, a low surface energy layer formed on one side of the conductive support layer, and a heat generating layer formed on the other side thereof.
To achieve the second object, there is provided a fixing apparatus comprising a heat generating medium for image fixing constructed as mentioned above, and a power supplying means for supplying electric power or current to the heat generating medium, wherein a recording sheet bearing a toner image not yet fixed is pressed against the heat generating medium which generates heat when receiving current from the power supplying means.
REFERENCES:
patent: 4745431 (1988-05-01), Kogure et al.
patent: 5115279 (1992-05-01), Nishikawa et al.
patent: 5151719 (1992-09-01), Akutsu et al.
patent: 5349423 (1994-09-01), Nagato et al.
patent: 56-7236 (1981-02-01), None
patent: 58-36337 (1983-08-01), None
patent: 59-21557 (1984-05-01), None
patent: 2-19879 (1990-01-01), None
patent: 3-144676 (1991-06-01), None
patent: 4-114184 (1992-04-01), None
Akutsu Eiichi
Ando Shigehito
Ogi Kenji
Takayama Hiroshi
Uehara Yasuhiro
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Fuji 'Xerox Co., Ltd.
Heinrich Samuel M.
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