| 摘要 |
<p>PROBLEM TO BE SOLVED: To precisely transfer an output even to a measuring device having a narrow input range by providing a voltage adding circuit for adding a prescribed voltage to the output of a subtracting circuit for detecting the difference in terminal-to-terminal voltage between thermosensitive elements on the upstream side and downstream side of a fluid. SOLUTION: A sensor driving part 2 has a first and second thermosensitive elements 11, 12 arranged on the upstream side and downstream side of a fluid. A subtracting circuit 21 detects the difference in terminal-to-terminal voltage between the thermosensitive elements 11, 12, and the output voltage of the subtracting circuit 21 and the output voltage of a reverse amplifier 13 are inputted and added to the adding circuit 14 of a differential voltage detecting part 3. In a voltage adding circuit 5, an adding circuit 18 adds a prescribed constant voltage outputted from a constant voltage source 19 to the output of the adding circuit 14 amplified by an amplifier 17. Since a prescribed voltage can be added to the output of the subtracting circuit 21, the output voltage of a flow sensor 1 can be regulated so as to fit the limited input range of a measuring device such as A/D converter to precisely transfer the output. Further, this device can cope with the variations of the thermosensitive elements by manufacturing error.</p> |
