| 摘要 |
<p>PROBLEM TO BE SOLVED: To especially enhance the output sensitivity in an air flow rate sensor to be used in an engine control system such as an automobile. SOLUTION: The flow rate sensor is made up of a semiconductor substrate 1 in which a thin thickness part 3 is formed by an anisotropic etching, an exothermic resistor 5 formed on this thin thickness part 3, and temperature sensing resistors 6, 7 and 33, 34 provided at least each two on the upstream and downstream of the exothermic resistor 5; and by utilizing the property that the resistances of the temperature sensing resistors 33, 34 are changed by the flow velocity, the gain of a temperature difference detecting circuit and the constant current value and the bias voltage are provided with a flow dependance, so that the sensitivity of the air flow rate sensor can be enhanced, and also the measurable flow-rate range can be enlarged.</p> |
