| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a flow rate measuring device capable of even further improving in reducing power consumption and in enhancing accuracy of a flow rate measurement. <P>SOLUTION: A timer unit of a flow rate measuring device includes: a first counter that starts to count at a starting point for measuring a propagation time; and a second counter that starts to count at an ending point for measuring the propagation time and counts at a speed higher than the first counter. A propagation time T0 is finally obtained by subtracting a period of time Δt, that is measured by the second counter until the first counter counts up from the ending point, from a period of time T1, that is measured by the first counter until the first counter counts up after passing the ending point from the starting point. A flow rate calculation part accurately calculates a flow rate by means of the propagation time T0. <P>COPYRIGHT: (C)2012,JPO&INPIT |
