| 摘要 |
PURPOSE:To break an unstable contact state by detecting relatively large electric current from detecting contacts while a cleaning switch opened or closed from the outside is held closed. CONSTITUTION:The negative pole of a battery 38 is connected to the ground terminal of a processing circuit 32, while its positive pole is connected from a contact holder 30 to the sliding contacts 14, 24 of contacts 10, 20, and further the positive pole of the battery 38 is directly connected to the power source input terminal of the circuit 32. A contact cleaning circuit 40 is connected to the respective detecting contacts 10, 20. The circuit 40 includes a cleaning switch 42 to be opened or closed from the outside, a resistance 44 connected in series to the switch 42, and a light emitting diode 46. While the switch 42 is held closed, relatively large electric current is supplied to the contacts 10, 20, by which the surfaces of the contacts 10, 20 are cleaned. |
