| 摘要 |
<p>PURPOSE:To enhance detection sensitivity, by raising the temp. of the temp.- sensitive element arranged in an air stream to be measured to specific one by applying power with definite voltage to said temp. sensitive element and measuring the power applying time at this time. CONSTITUTION:A temp.-sensitive element 12 and an auxiliary temp.-sensitive element 13, both of which have a temp. resistance characteristic, are arranged in a pipe 11 and constitute a bridge circuit along with fixed resistors 14, 15. A transistor 16 is brought to a continuity state by FF18 set by a current supply start signal and a power source +B is connected. When the temp. of the temp.- sensitive element 12 reaches a specific value, a comparator 17 is operated and FF18 is reset to cut off the power source +B. Because the connection time of the power source +B corresponds to the flow amount of air, the pulse width output of FF18 is taken in a control unit 19 through a driver circuit 20 and an interface circuit 25 and used as a flow amount signal. By this method, output with high detection sensitivity is obtained by a simple circuit.</p> |
