HUMIDITY MEASURING METHOD

• Main Authors: SAIKI TAKEHIKO, YAGI HIDEAKI
• Format: Patent
• Language: English
• Published: 20.01.1992
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PURPOSE:To allow the rapid resetting of the measuring state of a humidity sensor and to improve measurement accuracy by switching a heater to the set temp. higher than the service atmosphere temp. by >=20 deg.C and below 200 deg.C right after heating and cleaning. CONSTITUTION:A microcomputer (MIC) 11 impresses 20V voltage to the ceramics PTC heater 3 to put a ceramics humidity sensor 4 into a heating and cleaning state when the switch of a heater of a microwave oven is turned off. The contaminants, such as animal oils, sticking to the sensor 4 are then removed. The MIC 11 impresses 3V voltage to the heater 3 to put the sensor 4 into the measuring state when the switch of the microwave oven is turned on. Namely, the impressed voltage of the heater 3 is switched from 20V at which the surface temp. of the heater 3 attains 550 deg.C to 3V at which the surface temp. attains 70 deg.C. The surface temp. of the heater 3, therefore, falls rapidly from 550 deg.C toward 70 deg.C. Since the heater 3 heats the sensor 4 both at the time of the heating and cleaning and at the time of the humidity measurement and, therefore, the sensor is not contaminated and is improved in the accuracy.