Three-electrode sensor for phase comparison and pulse phase adjusting circuit for use with the sensor

Abstract

Two capacitors (C1, C2) having an identical structure and equal capacitance are used in series connection for the detection of phase difference so that ambient temperature affects both the capacitors in a similar manner to compensate for the variation in electrostatic capacitance. The sensor according to one embodiment has a lamination structure that a detection capacitor (C1) is closely attached to a comparison capacitor (C2) providing a short time period for thermal equilibrium of both capacitors. According to another embodiment sensor, since lamination capacitors having identical structure and identical characteristic are electrically connected in series, it is now possible to locate both capacitors at desired points which are spaced apart. A member (34) having a high heat conductivity may be arranged in a space between both the capacitors to thereby reduce the time required for thermal equilibrium. In a pulse phase adjusting circuit used for processing an output signal from the sensor, a variable d.c. voltage is applied via a resistor (R3) to a junction between the detection capacitor (C1) and a resistor (R1), to which junction gate of an FET is connected, so as to control delay time of the pulse, making it possible to perform remote control using a variable resistor (20).

Dependencies are inferred from the claim text.