Pressure sensor device

Abstract

Abstract PURPOSE:To obtain a pressure sensor device whose temperature fluctuation is small, by combining a series circuit of first and second capacitors whose electrostatic capacities are changed in correspondence with the change of pressure, a voltage generating circuit, and a comparator amplifier circuit which compares a voltage across the capacitor and a reference voltage. CONSTITUTION:A voltage generating circuit 1 is constituted by a transistor (TR) 7 which is switched by the output of an oscillator 6 and resistors. A series circuit 2 is constituted by a first capacitor 10 and a second capacitor 11 whose electrostatic capacities are changed in correspondence with the change of pressure. When the input voltage is applied to the siries circuit 2 and the TR 7 is OFF, an output voltage is Vout. When the TR 7 is ON, the output voltage is 0V. At this time, the amplitude of the voltage at a connecting point is Cp/Cr+CP.Vout, where Cp and Cr are the capacities of the first and second capacitors, respectively. Negative feedback is applied by an operation amplifier 21 so that the output voltage of an amplitude detecting circuit 3 becomes a reference voltage which is obtained by a reference voltage generating circuit 4. When Vout changes by the change of the Cp, the relationship Vout =(1+Cr/ Cp)Vref is established, and the change in electrostatic capacity can be efficiently taken out as the change in voltage.

Inventors

• 👤 Masaki Nakamura
• 👤 正樹 中村
• 👤 Wataru Takahashi
• 👤 渉 高橋
• 👤 Nobuo Ganji
• 👤 伸夫 元治
• 👤 Yoichi Kawai
• 👤 川井　与一

Bibliographic Details