Heating roller assembly for electrophotographic printer and method of making the same

#This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for HEATING ROLLER ASSEMBLY FOR ELECTROPHOTOGRAPHIC PRINTER earlier filed in the Korean Industrial Property Office on Feb. 22, 2001 and there duly assigned Ser. No. 9038/2001 by that Office.

#1. Field of the Invention

#The present invention relates to a heating roller assembly in an electrophotographic printer for fixing a toner or developed image on a printing medium, and more particularly, to a direct-heating type heating roller assembly including a power connecting member mounted on both a heating layer and a protective layer.

#A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:

#FIG. 1 is a schematic cross-sectional view illustrating an electrophotographic printer;

#FIG. 2 is a perspective view illustrating a direct heating type heating roller;

#Turning now to the drawings, FIG. 1 shows a fixing unit 10 of an electrophotographic printer. Fixing unit 10 includes a heating roller 30 and a backup roller 20. A printing medium 11 having a developer 12 formed by a developing unit (not shown) passes between heating roller 30 and backup roller 20. Heating roller 30 functions to press and heat developer 12 and printing medium 11, thereby fixing developer 12 on print medium 11.

#A reference numeral 13 denotes a temperature sensing means for sensing a temperature on a circumferential outer surface of heating roller 30. Temperature sensing means 13 includes at least one thermistor which is arranged on the circumferential outer surface of heating roller 30. Generally, heating rollers are divided into an indirect heating type heating roller and a direct heating type heating roller. Heating roller 30 can be used not only in the above-described fixing unit 10 but also in a different type of fixing roller for heating and pressing a toner image or a developer and a printing medium.

#Referring to FIGS. 2 and 3, there is illustrated a direct heating type heating roller 30. A heating layer 35 made of a current resistance material is directly disposed around deposited on a cylindrical circumferential outer surface of an inner insulating layer 34 of a cylindrical body 33. Also, a pair of power connecting members 39 each having a ring-shaped structure are respectively inserted around and coupled to respective terminal portion 35a of heating layer 35 so that electric power is supplied to heating layer 35 through power connecting member 39 which is connected to an external power source. Because heating layer 35 is made of the current resistance material, the temperature of heating roller 30 rises by the heat generated from heating layer 35 in response to the transmitted electric power.