| 摘要 |
PROBLEM TO BE SOLVED: To make measurable a liquid level even in the case that the location of the liquid level is low by controlling an amplification factor according to the time from the activation of an ultrasonic sensor in an ultrasonic level meter having the ultrasonic sensor mounted to the bottom surface of a container for transmitting and receiving ultrasonic waves to and from the liquid level in the container. SOLUTION: A control part 10 is connected to the ultrasonic sensor 20, has a time-variable characteristics amplification means 13a and a reverberation margin detection means 18, measures both the time between the activation of the sensor 20 and the reception of reflected echoes from the liquid level and the time from the activation of the sensor 20 until reverberation of the ultrasonic waves at the bottom surface of the container immediately after the activation is reduced to a prescribed level, detects a measured time difference as a reverberation margin, reduces the amplification factor at the activation of the sensor 20 in the case that the reverberation margin is of a prescribed value or smaller, and changes the amplification factor in such a way as to become greater with the passage of time, and adjusts the amplification factor in such a way that the detected reverberation margin may take the prescribed value or greater so as to be able to specify the reflected echoes from the liquid level. COPYRIGHT: (C)2004,JPO&NCIPI |
