| 摘要 |
<p>PURPOSE:To enhance the linearity of the flow rate and output of a heat-sensitive type flow rate sensor composed of a winding system of a temp.-sensitive resistance wire by providing the feedback circuit using a resistor ranging from an amplifier for amplifying the output of a bridge circuit to a constant current power supply. CONSTITUTION:An upstream heating resistor 1 and a downstream heating resistor 2 are wound around a fine sensor pipe 5 made of a metal having a gas inflow port 6 and a gas outflow port 7 and a bridge circuit is constituted of other two resistors R5, R6. The resistor Rf constituting the feedback circuit from an amplifier for amplifying the output of said bridge circuit to a constant current power supply is provided and, by feeding back the difference voltage between sensor output voltage VO and reference voltage VZ to the constant current power supply in the ratio determined by the feedback resistor Rf and an input resistor Ri, the output of said bridge circuit is adjusted to change the value of the current supplied to the bridge circuit to attain the linearilization of output. As mentioned above, by adding only one feedback resistor, the straight line range between a flow rate and the output of the sensor is magnified about three times.</p> |
