Temperature measurement method of vibration type level sensor, object detection method and object detection apparatus

摘要

PROBLEM TO BE SOLVED: To provide a temperature measuring method, an object detecting method and an object sensing device for a vibratory level sensor capable of reducing the number of parts to enhance reliability.;SOLUTION: In these methods, first an electromagnet (21) is made to face magnet (22) attached to a diaphragm (23) in a sensing pipe through some Gap Field, then a drive circuit (51) is used to apply an alternating current with any frequency within the given limits centering on the resonance frequency of the diaphragm swept, to a coil for each specified measurement cycle. When this AC current is applied, a phase comparator (53) detects any phase variation arisen depending on whether an object adheres to the diaphragm or not, while a microcomputer (40) discriminates the presence of the object based on the detected phase variation as well as measuring temperature based on the phase variation detected in the first half period of the given measurement cycle, changing the frequency to be swept based on the measured result of temperature during the latter half period of the given measurement cycle.;COPYRIGHT: (C)2004,JPO