| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a sensor which detects surely approach of an object and a sensor constitution capable of coping with low cost and miniaturization. SOLUTION: In this capacitance type proximity sensor, approach of an object 9 to a sensor electrode 19 is detected on the basis of change of capacitance by using a resonance circuit 15. Electrode capacitance Cs of the sensor electrode 19 and capacitance Ci which a resonance circuit has are made resonance capacitance C. The resonance capacitance C and a resonance inductor L are connected in series, and the series resonance circuit 15 having resonance frequency fr is formed. When the series resonance circuit 15 is made to resonate at an exciting frequency f0, it is set higher than the resonance frequency fr, and the object 9 is detected on the basis of resonance voltage Vr of the series resonance circuit.</p> |
