| 摘要 |
PURPOSE:To prevent reduction in press sensitivity of a pressure-sensitive sensor in a pressure-detection circuit. CONSTITUTION:A pressure-sensitive sensor 2 whose resistance Rs changes according to applied force is connected between an input terminal and an output terminal of an inversion amplifier 1 and then a resistor 3 is connected to the input terminal. On the other hand, an output terminal 5 and a non-inverted input terminal of a second amplifier 6 are connected to the output terminal. A reference voltage source 7 generating a reference voltage Eref is connected to the inverted input terminal of the second amplifier 6 and then a voltage follower 11 is connected to the output terminal through a time-constant circuit 8. The time-constant circuit 8 is provided with a resistor 9 which is connected between the output terminal of the second amplifier 6 and the non-inverted input terminal of the voltage follower 11 and a capacitor 10 which is connected to the non-inverted input terminal. The other terminal of the resistor 3 is connected to the output terminal of the voltage follower 11. |
