| 摘要 |
PROBLEM TO BE SOLVED: To prevent a foreign matter from being adhered to a heating resistor to change the resistance value by providing a protecting film and/or a member for preventing the penetration of foreign matters on the heating resistor. SOLUTION: A heating resistor 3 is provided on the inner surface side of a cylinder 1, and a protecting film 8 for covering the heating resistor 3 and/or a member for preventing the penetration of foreign maters (electrode member 5) are provided thereon. The protecting film 8 is formed of a resin such as polyimide or fluorine resin, or glass, which has a decomposing temperature of 400 deg.C or more. The protecting film 8 covers the whole surface of the resistor 4 exposed to the inside surface, an the thickness is set to 1.0μm or more. The electrode member 5 is also sued and made into a form as covers the end part of the cylinder 1, whereby a foreign matter is prevented from being penetrated to the inner part. Thus, when the resistor 3 is partially laser-worked to form a groove to regulate the resistance value, the foreign matter can be prevented from being penetrated into the groove.
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