1. Field of the Invention
The present invention relates to a fixing apparatus provided in an image forming apparatus, such as a copying machine, a printer, and a facsimile, and a roller used in the fixing apparatus, and in particular, a fixing apparatus of an image forming apparatus and a roller using an induction heating system.
2. Description of the Background
In a fixing apparatus that adopts an induction heating system and is used in an image forming apparatus, such as an electrophotographic copying machine or printer, there is a device that increases the fixing speed by speeding up a warming up time of the fixing apparatus. For example, JP-A-2002-295452 discloses a heating device that heats a metal sleeve, which is positioned on the outer periphery of an elastic layer of a heat roller and has a small heat capacity, using an induction coil to thereby shorten a warming-up time.
However, in the known device, handling of expansion or contraction that occurs to the elastic layer when warming up or cooling the elastic layer is not mentioned.
Therefore, in a case when a metal belt having a metal layer on the outer periphery of an elastic layer is provided, it is preferable to develop a fixing apparatus of an image forming apparatus capable of increasing the life of the metal belt and an elastic roller by preventing the metal belt or the elastic layer from being broken at an early stage regardless of expansion or contraction occurring to the elastic layer.