| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid level detector capable of detecting a liquid quantity as a liquid level with a simple structure using a surface acoustic wave device. SOLUTION: The liquid level detector 10 comprises: a first IDT electrode 50 formed on the main surface of a piezo-electric substrate 40; a second IDT electrode 60 which is spaced from the first IDT electrode 50 in a propagation direction of a surface acoustic wave; a common input/output terminal 58 of the first IDT electrode 50 and the second IDT electrode 60; and a control section 70 having the surface acoustic wave device 30 which is disposed such that the propagation direction of the surface acoustic wave is approximately vertical to the liquid level of a liquid, and at least a transmitting circuit for inputting an input signal to the input/output terminal 58 and a detecting circuit for detecting a response time defined from inputting of the input signal up to outputting of its response signal. The liquid level is detected from a change in the response time caused by a position at which the second IDT electrode 60 is immersed in the liquid. COPYRIGHT: (C)2008,JPO&INPIT
|
