| 摘要 |
PROBLEM TO BE SOLVED: To easily detect an abnormality of a contact resistance while a pull- down resistance is always being operated. SOLUTION: A resistance means 26 one end of which is connected to a measuring terminal 24 and the other end of which is connected to a ground is installed at a measuring part 12. A switch 36 used to change over a continuity state/a discontinuity state across a second resistance 34 and the measuring terminal 24 is installed at the resistance means 26. When a voltage value Vm1 and a voltage value Vm2 of the measuring resistance 24 before and after the switch 36 is changed over are measured, a contact resistance value Zco is calculated, and the abnormality of the contact resistance 28 is detected easily. Since the resistance means 26 functions as the pull-down resistance irrespective of the continuity state/the discontinuity state of the switch 36, an influence due to a noise is always suppressed, and an abnormality due to a disconnection is always detected. COPYRIGHT: (C)2004,JPO
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