| 摘要 |
PURPOSE:To enable measurement of a slight change in atmospheric pressure without being affected by ambient temp. by providing a constant voltage power source to the input terminal of a bridge circuit constituted of pressure sensitive resistance elements provided to a semiconductor pressure sensor and a voltage generating circuit to the output terminal thereof. CONSTITUTION:The two input terminals of an amplifier 24 are connected respectively to output leads 9, 9' of a bridge, via an additive resistor 25 and a voltage generating circuit 27 at the one terminal and via an additive resistor 25 at the other terminal. The circuit 27 consists of a constant voltage power source and a voltage dividing resistor 29. The voltage between the two terminals 30 and 31 can be selected optionally by shifting the connecting position of the terminal 30 on the output lead 9 side. The voltage corresponding to the atmospheric pressure is kept outputted between the leads 9 and 9'. If the position of the terminal 30 is so adjusted as to generate the voltage corresponding to the atmospheric pressure between the terminals 30 and 31 in this state, the voltage between the two input terminals is made zero. If, therefore, the voltage between the leads 9 and 9' changes with a change in the condition of the atmospheric pressure, only the change component of the voltage is amplified by the amplifier 24 and a slight change in the atmospheric pressure is exactly measured. |
