CAPACITANCE VARIATION DETECTION CIRCUIT

• Main Authors: SONOZAKI TOMOKAZU, AKAI HIROSHI, ARAI IKUO
• Format: Patent
• Language: English; Japanese
• Published: 12.10.2017
• Subjects: BASIC ELECTRONIC CIRCUITRY; DETECTING MASSES OR OBJECTS; ELECTRICITY; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; MEASURING; PHYSICS; PULSE TECHNIQUE; TESTING

PROBLEM TO BE SOLVED: To provide a capacitance variation detection circuit that offers an extended range of detectable capacitance variation.SOLUTION: A capacitance variation detection circuit 20 comprises a Colpitts oscillator circuit 14, a human body detector section 8, a variable resistance circuit 9, an amplitude detection circuit 16, and a signal amplifier circuit 12. The amplitude detection circuit 16 changes resistance R3 of the variable resistance circuit 9 in accordance with an amplitude of output voltage Vd of an amplifier circuit 4. When the Colpitts oscillator circuit 14 stops oscillating in response to a capacitance change of the human body detector section 8, the amplitude detection circuit 16 changes the resistance of the variable resistance circuit 9 such that the oscillation is resumed.SELECTED DRAWING: Figure 1 【課題】検出可能な静電容量の変化の範囲が拡大された静電容量変化検出回路を提供する。【解決手段】静電容量変化検出回路２０は、コルピッツ発振回路１４と、人体検知部８と、可変抵抗回路９と、振幅検出回路１６と、信号増幅回路１２とを含む。振幅検出回路１６は、増幅回路４の出力電圧Ｖｄの振幅に応じて可変抵抗回路９の抵抗値Ｒ３を変化させる。振幅検出回路１６は、人体検知部８の静電容量変化に応じてコルピッツ発振回路１４の発振が停止したときに、発振が再開するように可変抵抗回路９の抵抗値を変化させる。【選択図】図１