| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To sufficiently ensure flow detection accuracy even when the environmental temperature has changed in a thermal flow sensor constituted in such a way as to detect the flow rate of a test fluid through the use of a heat resistor and a pair of thermometric resistors. <P>SOLUTION: The energization of the heat resistor is periodically turned on and off to compute a voltage Vs, sensor output, on the basis of bridge output Vb, a detection signal of a resistance difference between the pair of thermometric resistors. At this point, with the time between a point of time (ton) when the energization of the heat resistor is turned on and a prescribed point of time (t1) prior to the saturation of a value of the bridge output Vb as a half period T/2, the turning on/off is performed, and a voltage Vs, sensor output, is computed on the basis of the amplitude of AC signals output by the turning on/off. It is thereby possible to detect the flow rate without having to use sensor output when the flow rate of the test fluid is zero as a sensor output reference. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
