Electric heating – Heating devices – Combined with diverse-type art device
Reexamination Certificate
2000-07-12
2001-09-04
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with diverse-type art device
C219S469000, C399S330000, C399S333000
Reexamination Certificate
active
06285006
ABSTRACT:
TECHNICAL FIELD
The invention relates to the heater/fuser rollers for use in copy machines, printing applications and industrial uses.
DESCRIPTION OF THE BACKGROUND ART
The conventional copy machine fuser roller uses a non-rotating quartz lamp inside the rotating fuser roller core.
The inside of the aluminum core has a black coating to promote heat absorption. All heat transfer to the roller core tube is by radiation from the quartz lamp. This is inefficient and requires higher temperature at the lamp surface to transfer heat for a given power level, than does heat transfer by conduction. The roller also has an outer cover of silicone rubber, Teflon, or another release layer that will operate at high temperature to prevent toner build-up.
Ceramics have been proposed for heater/fuser rollers in Kogure, U.S. Pat. No. 4,813,372 and U.S. Pat. No. 4,801,968; Urban, U.S. Pat. No. 4,810,858; and Yuan, U.S. Pat. No. 5,191,381. The designs in these patents are complex and not readily adapted to present day manufacturing and use. These designs typically place the ceramic layer on the outside of the roller core.
Hyllberg, U.S. Pat. No. 5,408,070, discloses a heater/fuser roller with a thermal regulating layer and a heating layer disposed inside the roller core.
A general object of the present invention is to improve on the prior art ceramic heater roller construction to provide a simple, low cost, easy to manufacture ceramic heater roller with the heater inside a hollow center of the roller core and without a thermal regulating layer of type seen in U.S. Pat. No. 5,408,070.
Recently, energy saving guidelines for copiers have required shorter ramp up times to the fusing temperature (about 200° C., 392° F.), lower idling temperatures to reduce heat losses, and lower heat losses over all.
A further object of the present invention is to provide a ceramic heater/roller with internal heater that provides improved ramp up operation to the fusing temperature.
Hyllberg, U.S. patent application Ser. No. 84,650, issued as U.S. Pat. No. 5,420,395, discloses a roller with electrode bands formed on a heater layer inside of a roller core. It is further object of the invention to improve upon the arrangement disclosed there by providing contact assemblies that fit within the roller and provide continuous electrical connection as the roller is being rotated.
SUMMARY OF THE INVENTION
The invention concerns a thermal conduction roller having a tubular roller core with an inside surface, an electrical insulator coat primarily of zirconia on the inside surface, a heater coat disposed over the insulator coat, and at least two electrical contact assemblies that are disposed inside the roller and provide continuous electrical connection to the heater coat as the roller is being rotated.
A particular advantageous embodiment utilizes an electrical insulator coat in a range of thickness from about ten mils to about twenty mils. A thinner coat may not have sufficient dielectric strength, while a thicker coat decreases thermal conduction.
In most embodiments a release material is applied to the outside of the roller.
It is also advantageous to seal the insulator coat with a silicone elastomer.
Titania is a preferred material for the heater coat, although blends of titania and other ceramic materials or metals or alloys may also be used.
Various contact structures according to the present invention are also described in detail, including one especially adapted to connect to a three-phase power supply.
Other objects and advantages of the invention, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiments which follow. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. Such examples, however, are not exhaustive of the various embodiments of the invention, and therefore, reference is made to the claims which follow the description for determining the scope of the invention.
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patent: 4810858 (1989-03-01), Urban et al.
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patent: 4820904 (1989-04-01), Urban
patent: 5093556 (1992-03-01), Oelfke
patent: 5191381 (1993-03-01), Yuan
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patent: 6122479 (2000-09-01), Fujita et al.
patent: 6137969 (2000-10-01), Tsujimoto
American Roller Company
Pelham Joseph
Quarles & Brady LLP
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