| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a thermal flow sensor with good sensitivity in measuring the quantity of flow of a fluid. SOLUTION: A thermal flow sensor comprises a silicon substrate 1, a cavity provided in the silicon substrate 1, a thin-wall part 3 provided by covering the cavity with an insulating layer, a substrate temperature detecting resistance 8 formed on the silicon substrate 1 except the thin-wall part 3, and a heating resistance provided on the thin-wall part 3 and detects the quantity of flow of a fluid flowing on the heating resistance 5 on the basis of changes in current flowing through the heating resistance 5 by controlling the heating of the heating resistance 5 so that the temperature of the heating resistance 5 may be maintained at a temperature higher than that of the substrate temperature detecting resistance 8 by a predetermined temperature. The thermal flow sensor is provided with a second heating resistance 19 on the thin-wall part 3 more downstream in the fluid than the heating resistance 5.</p> |
