| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the resistance change of a semiconductor film by forming this semiconductor film on the outer peripheral surface of a bell head body made of a high-resistance material and, further, forming a high-resistance film having resistance on the outer Peripheral surface of the semiconductor film. SOLUTION: The bell head 4 is constituted by forming the semiconductor film 2 over the entire area of the outer peripheral surface of the bell head body 1 made of the high-resistance material and forming the high-resistance film 8 having chemical resistance and solvent resistance over the entire area on the outer peripheral surface of the semiconductor film 2. The high-resistance film having the resistance is formed on the outer peripheral surface of the semiconductor film in such a manner and, therefore, there is no formation of the electric resistance wire between the semiconductor film and a metallic coating material and the electric resistance does not change in spite of contact of the metallic coating material. In addition, the semiconductor film is isolated from chemicals and solvents and is not eroded. There is thus no electric resistance by erosion either.</p> |
