Ceramic heater roller and methods of making same
First Claim
1. A three-layer thermal conduction roller in which a voltage is applied to the roller to cause heating within a heating layer, the roller comprising:
- a cylindrical roller core;
a first layer of an electrical insulating material disposed around the cylindrical roller core;
a second layer of a semiconductive heating ceramic disposed around the insulating layer and the cylindrical roller core; and
an outermost layer, which forms the outer surface of the roller, the outermost layer being disposed around and over the semiconductive heating layer for conducting and carrying heat to a work object, the outermost layer being electrically insulative;
wherein the second layer is formed of at least one plasma-sprayed coating of ceramic material; and
wherein a resulting composition of the ceramic material and volume resistivity of the second layer are controlled by controlling the hydrogen secondary plasma gas level as the ceramic material is plasma-sprayed longitudinally alone the roller.
10 Assignments
0 Petitions
Accused Products
Abstract
A thermal conductive roller for use in copying machines, steam-heated and induction-heated applications includes a ceramic heating layer formed by plasma spraying a ceramic material to form an electrically conductive heating layer of preselected and and controlled resistance. Several methods of controlling the resistance of the ceramic heating layer are disclosed. The ceramic heating layer is sealed with a solid, low viscosity sealer such as Carnauba wax to protect the ceramic layer from moisture penetration. Electrical current is applied at or near the core and is conducted radially outward through the heating layer to an outer grounded metallic layer. An outer contact layer of metal, ceramic, or polymeric material can be added.
54 Citations
24 Claims
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1. A three-layer thermal conduction roller in which a voltage is applied to the roller to cause heating within a heating layer, the roller comprising:
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a cylindrical roller core; a first layer of an electrical insulating material disposed around the cylindrical roller core; a second layer of a semiconductive heating ceramic disposed around the insulating layer and the cylindrical roller core; and an outermost layer, which forms the outer surface of the roller, the outermost layer being disposed around and over the semiconductive heating layer for conducting and carrying heat to a work object, the outermost layer being electrically insulative; wherein the second layer is formed of at least one plasma-sprayed coating of ceramic material; and wherein a resulting composition of the ceramic material and volume resistivity of the second layer are controlled by controlling the hydrogen secondary plasma gas level as the ceramic material is plasma-sprayed longitudinally alone the roller. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A three-layer thermal conduction roller for use in industrial applications in which a voltage is applied to the roller to cause heating within a heating layer, the roller comprising:
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a cylindrical roller core; a first layer of an electrical insulating material disposed around the cylindrical roller core; a second layer of a semiconductive heating ceramic disposed around the insulating layer and the cylindrical roller core; and an outermost layer, which forms the outer surface of the roller, the outermost layer being disposed around and over the semiconductive heating layer for conducting and carrying heat to a work object, the outermost layer being electrically insulative; wherein the second layer is formed of at least one plasma-sprayed coating of ceramic material; and wherein the outermost layer is a plasma-sprayed ceramic material. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of making a thermal conduction roller in which a voltage is applied to cause heating within a heating layer disposed between an inner insulating layer and an outer contact surface, the method comprising:
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plasma spraying a ceramic material in one or more sublayers to form an electrically semiconductive ceramic heating layer of controlled resistance between the insulating layer and the outer contact surface; selecting the hydrogen secondary plasma gas level as the ceramic material is plasma-sprayed along the length of the roller to control the volume resistivity and composition of the one or more sublayers of ceramic material; and applying an outer functional layer of an elastomeric material around and over the ceramic heating layer. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method of making a thermal conduction roller for use in industrial applications in which a voltage is applied to cause heating within a heating layer disposed between an inner insulating layer and an outer contact surface, the method comprising:
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plasma spraying a ceramic material in one or more sublayers to form an electrically semiconductive ceramic heating layer of controlled resistance between the insulating layer and the outer contact surface; and applying an outermost functional layer of ceramic material around and over the ceramic heating layer; wherein the outermost functional layer is applied by plasma spraying a ceramic outer layer around and over the ceramic heating layer. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification