| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a thermal flowmeter which can suppress a nonuniformity in a flow detecting characteristic caused by the nonuniformity in the temperature change characteristic of a heating element, a heat-sensitive element and a temperature detecting element and thus enables simple and easy compensation of the temperature thereof. <P>SOLUTION: The thermal flowmeter is equipped with a sensor chip having the heating element Rh, the heat-sensitive elements Ru and Rd in a pair and the temperature detecting element Rr formed on the same chip. A positive temperature change characteristic of a heater circuit which is a bridge circuit formed by using the heating element Rh, the temperature detecting element Rr and fixed resistances R1 and R2 and keeps the heating temperature constant with drive voltage subjected to a feedback control, is canceled by a negative temperature change characteristic of a heater circuit which is a bridge circuit formed by using the paired heat-sensitive elements Ru and Rd and fixed resistances Rx and Ry and is driven by a constant voltage source. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
