Toner image fixing apparatus
AssigneeKabushiki Kaisha Toshiba
InventorsMitutosi Kogure, Yuka Nakamura, Makoto Tamura
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Abstract
A thermal roller for fixing a powdered toner image onto an image receiving sheet is provided with a sub-surface resistive heat generating layer adjacent the outer surface of the roller. The thickness of the heat generating layer or the materials that constitute the layer are controlled so that the resistance per unit length of the thermal roller increases gradually in the axial direction from the center portion thereof toward and to both ends. Electrical energy passed through the heat generating layer generates a desired temperature distribution profile along the roller to provide appropriate fixing temperatures, without excessively increasing the temperature at both ends of the roller.
Claims21
A toner image fixing apparatus for fixing a toner image on an image fixing material of any given width passed between fixing rollers made up of a thermal roller and a pressure roller brought into pressure contact with the thermal roller, wherein said thermal roller comprises a resistive heat generating layer formed integrally with said thermal roller near and throughout an outer surface thereof, the resistance per unit length distribution in the axial direction of said resistive heat generating layer increasing gradually from a center of said thermal roller to both ends thereof to obtain a temperature distribution on a surface of said thermal roller such that the temperature gradually decreases from the center of said thermal roller to both ends thereof, and wherein said resistive heat generating layer is formed with a roughened surface on both sides thereof to increase the heat generating area thereof.
A thermal toner-fixing roller for fixing a powdered toner image onto an image receiving material, comprising:
- a cylindrical body having a surface of revolution formed about an axis;
- an axially extending, electrically resistive layer on said surface having a non-uniform resistance value per unit axial length, said electrically resistive layer formed with a roughened surface on both sides thereof to increase the heat generating area thereof;
- and
- means at opposite axial ends of said resistive layer for connecting said resistive layer in an electrical circuit, whereby a current flow in said resistive layer between said axially opposite connecting means causes a temperature distribution on a surface of said body such that the temperature gradually decreases from the center of said body to both ends thereof.
Dependencies are inferred from the claim text.