| 摘要 |
PROBLEM TO BE SOLVED: To easily find the fraudulent alteration when a metal ball detector is fraudulently altered and to effectively prevent the fraudulent alteration. SOLUTION: The metal ball detector 10 includes a through-hole 27 where a metal ball passes through, a detection coil 24 arranged around the through-hole 27 for detecting the passing of the metal ball, a detection circuit for detecting magnetic change generated in the detection coil 24, and a case body 12 provided with the through-hole 27 for covering the detection coil 24 and the detection circuit. The case body 12 has a main body case part 14 with an opening 15 and a cover part 16 for closing the opening 15. The main body case part 14 has a fitting part 52 at the side part, the cover part 16 has a part 63 to be fitted to the fitting part 52, and in the state of closing the opening 15 of the main body case part 14 with the cover part 16, the fitting part 52 and the part 63 to be fitted are calked and fixed by heat in the width direction of the case body 12. COPYRIGHT: (C)2009,JPO&INPIT
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