Ultrasonic liquid level indicator esp. for automatic analyser - has ultrasonic transmitter and receiver above liquid container and transmission arrangement preventing reflections at container aperture

摘要

The ultrasonic liq. level indicator has a transmission transducer (10) mounted above a liq. container opening (4a) defined by a peripheral edge (4b). The time intervals of the ultrasonic waves emitted by the transducer are controlled. A second transducer (12) above the aperture receives ultrasonic waves reflected from the liq. (2). The time from transmission to reception of the ultrasonic waves is measured. A transmission arrangement (8) ensures that only those ultrasonic waves which would not be reflected by the edge of the aperture are passed to the liq. surface. USE - Esp. for measuring liq. levels in automatic analyser containers, e.g. test tubes of small dia. for blood testing.