| 摘要 |
PURPOSE:To drive a capacity-type sensor with a simple constitution and prevent a detection error by inducting a quantity of electricity based on a capacity difference of an element whose electrostatic capacity changes according to a physical displacement to be detected. CONSTITUTION:Fixed electrodes SP1, SP2 of a sensor forming electrostatic capacities C1, C2 are connected to a clock input for FF at a switching part through FET for switching and an inverter IN21. An output Q from FF is of a waveform which has ''H'' period which meets a capacity C1 and also has ''L'' period which meets a capacity C2. This signal is given to an arithmetic part OP and averaged through integration action after differential amplification against a reference voltage. An output from the averaging process is proportional only to a differential change in the capacities C1, C2 and then is supplied to an output part OT, being converted to a current value. |
