CIRCUIT AND SENSOR FOR DETECTING ELECTROMAGNETIC FIELDS CLOSE TO LOW FREQUENCY, AND GAME MACHINE

摘要

PROBLEM TO BE SOLVED: To suppress malfunctions of a proximity switch generated by the approach of electromagnetic field close to a low frequency.;SOLUTION: A detection electrode 1 detects an induced voltage generated by an electromagnetic field close to a low frequency, and a coupling circuit 11 connected to the detection electrode in series adjusts the wave height or the level of the induced voltage generated in the detection electrode. The coupling circuit 11 and an LC resonance circuit 12, arranged between a ground potential set a detection allowable frequency of the induced voltage, and a high-frequency oscillation circuit 13 of a current-feedback type oscillates a high-frequency sine wave by an intermediate potential VLC between the coupling circuit 11 and the LC resonance circuit 12. When the electromagnetic field cose to the low frequency is non-irradiated to the detection electrode 1, the high-frequency oscillation circuit 13 set in a negative conductance generating oscillation stop; and when the electromagnetic field near the low frequency is irradiated to the detection electrode 1, the high-frequency oscillation circuit 13 is changed into an oscillation state. The present invention is applicable to game machines.;COPYRIGHT: (C)2011,JPO&INPIT