| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance-type detecting apparatus whose detecting range is wide, whose calibration operation by a manufacturer and a user is not required at all, which is handled easily, in which an irregularity in detecting sensitivity is eliminated, which can deal with a usage condition in a wide range and which is hardly influenced due to static electricity and due to the moisture and the adhesion of an object to be detected. SOLUTION: A power supply is turned on, and the output of a variable- frequency generation circuit is continued to be always matched to the resonance frequency of a resonance circuit 1. When the object to be detected is brought into contact with, or brought close to, a detection electrode so as to change the resonance frequency of the resonance circuit 1, a phase shift is generated between the resonance frequency of the resonance circuit 1 and the output of the variable-frequency generation circuit 5. The phase shift is detected by a phase comparison circuit 3. In order to match their phases, a control circuit 4 changes a control voltage so as to change the oscillation frequency of the variable-frequency generation circuit 5. When its change is detected by a detection circuit 7, whether the object to be detected exists or not is detected.
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