| 摘要 |
<p>PURPOSE: To calibrate a flow sensor in a short time without removing it by camouflaging flow change with a known electric circuit means and comparing it with a measurement output value in the same conditions. CONSTITUTION: In calibration, the responses of a flow sensor and a signal processing circuit 28 are first adjusted at a known flow rate and then a gas flow is made zero to electrically switch a current flowing in one resistance temperature gage 2 in a reproductive manner for observing the output of the circuit 28. Later, when the gas flow is made zero for inspection, a current flowing in the temperature gage 2 is switched to compare the output of the circuit 28 with the previous value. When switches 24, 26 are closed, a current in the temperature gage 2 is decreased and a temperature and a resistance value are dropped but a current in a resistance temperature gage 4 is somewhat increased and a temperature difference occurs between the temperature gages 2, 4. As fixed resistors 6, 8 keep their original resistance values, output voltage between output terminals 16, 18 is changed and the output of the circuit 28 is also changed. To offset these, the circuit 28 is controlled for its drift to be corrected.</p> |
