Electrophotography – Image formation – Fixing
Utility Patent
1999-03-31
2001-01-02
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Fixing
C219S619000, C399S333000
Utility Patent
active
06169871
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims benefit of priority to Japanese Patent Application Nos. 10-086611 filed Mar. 31, 1998; 10-086612 filed Mar. 31, 1998; and 11-021992 filed Jan. 29, 1999, the entire contents of which are incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fixing apparatus having a heating roller using an induction heating system.
2. Discussion of the Background
A known fixing apparatus used for image forming apparatuses such as a photocopying machine, a printer, and a facsimile, includes a heating roller using an induction heating system. In general in such a fixing apparatus having an induction coil is installed inside of a cylinder which forms the circumference of the heating roller, and an induction magnetic flux is generated by sending a high frequency alternating current to the induction coil. An induction current is generated in an electroconductive layer of the cylinder of the heating roller by the induction magnetic flux, and the heating roller is heated by joule heat generated by the induction current.
Because the induction coil is installed inside the heating roller, the fixing apparatus having the heating roller using the induction heating system has a problem in that the temperature of the induction coil is raised by radiant heat emitted from the cylinder of the roller and heated beyond a heat-proof temperature of the insulating cover of the coil. The fixing apparatus having the heating roller using the induction heating system has another problem in that fixing efficiency is not good, because heat generated in the cylinder of the heating roller is dispersed in the inside of the heating roller.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to overcome the above-described and other problems with background apparatuses, by providing a fixing apparatus having a heating roller using an induction heating system, which is capable of preventing temperature rise of an induction coil and improving fixing efficiency.
This and other objects are achieved according to a preferred embodiment of the present invention by providing a novel fixing apparatus having a heating roller using an induction heating system, and which includes an insulating member arranged between a cylinder of the heating roller that is the heating unit of the heating roller and a coil arranged inside the cylinder to generate an induction magnetic flux.
According to the invention, the insulating member may further include a heat-absorbing member on the outer surface of the insulating member.
According to another preferred embodiment, in a fixing apparatus having a heating roller using an induction heating system, a tubular member on which a coil is wound to generate an induction magnetic flux is arranged inside the heating roller and an outer circumferential surface of the tubular member communicates with the outside of the heating roller by a plurality of openings provided in the tubular member.
Further, in a fixing apparatus having a heating roller of an induction heating system, according to still another embodiment of the present invention, an insulating cylinder member is provided inside a cylinder of the heating roller substantially tightly contacting the inner circumference of the cylinder. The length of the insulating cylinder member in the axial direction of the cylinder member may be made longer than the length of the cylinder of the heating roller in the axial direction of the cylinder.
In addition, a spiral rib may be provided on the insulating cylinder member such that an upstream pitch of the spiral rib is shorter than a downstream pitch of the spiral in the direction of air flow caused by the rib when the cylinder member is rotated.
Furthermore, at least one additional insulating cylinder member may be provided inside the insulating cylinder member substantially tightly contacting the cylinder. The lengths of the insulating cylinder member contacting the cylinder and the at least one additional insulating cylinder member in respective axial directions may be made larger than the length of the cylinder of the heating roller in the axial direction of the cylinder.
Furthermore, an optional cylinder member among the at least one additional insulating cylinder member may be configured to rotate integrally with the cylinder of the heating roller and a spiral rib may be provided on the rotative cylinder member.
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Chen Sophia S.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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