| 摘要 |
PURPOSE:To improve the degree of freedom of setting of a temperature compensation circuit without loss of a resonance circuit by using an output based on a temperature change of a sermister provided to a sensor section of the resonance circuit so as to apply temperature compensation of the output of a proximity sensor. CONSTITUTION:When no object approaches a detection coil 1 of the sensor 3, an oscillation circuit is oscillated with an amplitude composing of a conductance of the resonance circuit composing of a coil 1 and a capacitor 2, and its output is converted into a DC voltage by a detection circuit 11 and given to an operational amplifier 15. When an object approaches the coil 1, an output increased corresponding to a distance from the oscillation circuit is obtained. On the other hand, the temperature change in the sensor section 3 is given to a voltage converting circuit as a resistance change in a thermister R11, the input voltage of the operational amplifier 13 is changed. Suppose that the temperature characteristic of the oscillation circuit has a positive temperature characteristic, a switch 14 is changed over in advance to decrement the characteristic by the output of the amplifier 13. Then the output of the amplifier 13 is fed to an inverting input of the operational amplifier 15 to apply temperature compensation.
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