| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic gas concentration sensor which has a lower operation voltage and is easily reduced in size.SOLUTION: There is provided a gas concentration sensor which includes an ultrasonic transmission element and an ultrasonic reception element arranged so as to face each other, and an arithmetic circuit connected to the respective elements, measuring the propagation time of the ultrasonic wave transmitted from the ultrasonic transmission element and received by the ultrasonic reception element to calculate the concentration of the gas interposed between the ultrasonic transmission element and the ultrasonic reception element, or a gas concentration sensor which includes an ultrasonic transmission/reception element and an ultrasonic reflection plate arranged so as to face each other, and an arithmetic circuit connected to the ultrasonic transmission/reception element, measuring the propagation time of the ultrasonic wave transmitted from the ultrasonic transmission/reception element and received by the ultrasonic transmission/reception element after being reflected by the reflection plate to calculate the concentration of the gas interposed between the ultrasonic transmission/reception element and the reflection plate. The ultrasonic transmission element, the ultrasonic reception element and the ultrasonic transmission/reception element are elements composed of a porous dielectric material molding and a pair of electrodes.SELECTED DRAWING: Figure 2 |
