Fusing and fixing unit of image forming apparatus

#This application claims the benefit of Korean Application No. 2002-18223, filed Apr. 3, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

#1. Field of the Invention

#The present invention relates to a fusing and fixing unit of an image forming apparatus, and more particularly, to a fusing and fixing unit of an image forming apparatus which is improved so as to increase the temperature of a fusing roller within a fast time and reduce a warm-up period.

#These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

#FIG. 1 is a schematic cross-sectional view of a fusing and fixing unit of an image forming apparatus according to an embodiment of the present invention;

#FIG. 2 illustrates the wavelength range of an infrared heat source of the fusing and fixing unit of the image forming apparatus according to the FIG. 1;

#Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

#Referring to FIG. 1, an image forming apparatus according to an embodiment the present invention includes a fusing roller 10, a pressing roller 20, and an infrared heat source 30. The fusing roller 10 rotates in a direction A in which a paper 1 to which a toner image is formed is discharged. The pressing roller 20 is installed so as to face the fusing roller 10 and rotates while elastically biased toward the fusing roller 10, by an elastic compressing member, e.g., a compressing spring 25. The infrared heat source 30 heats the fusing roller 10 up to a printing fusing temperature state. A thermostat 5 is installed above the fusing roller 10. The thermostat 5 intercepts power from a power supply (not shown) that supplies power to the infrared heat source 30 when the surface temperature of the fusing roller 10 sharply increases so as to prevent the fusing roller 10 from being overheated. A thermistor 7, which senses the surface temperature of the fusing roller 10, is installed on the fusing roller 10. By using the thermistor 7, the surface temperature of the fusing roller 10 is controlled to maintain a temperature which allows the toner image to be fixed to the paper 1 during a printing operation. In FIG. 1, reference character Iin represents toner images which are transferred to and placed on the paper 1, and reference character lout represents toner images which are fused and fixed to the paper 1.

#In the embodiment of FIG. 1, the fusing roller 10 includes a main member 11 of a tube type, which has hollow portions therein and is made of an opaque material, and an infrared absorbent layer 13, which is formed on the inner surface of the main member 11. The main member 11 is formed of a metallic material, preferably, an aluminium material (aluminium or aluminium alloy). The infrared absorbent layer 13 is formed by coating the inner surface of the main member 11 with a material that absorbs infrared rays.