| 摘要 |
PURPOSE:To make it possible to measure powder quantity in a container without fail by using a device on a comb shaped exciting electrode and one or more pairs of receiving electrodes on the surface of a piezoelectric substrate on which an elastic surface wave is propagated in the longitudinal direction. CONSTITUTION:A sensing element is formed by providing the comb shaped exciting electrode and several pairs of receiving electrodes on the surface of the piezoelectric substrate on which the elastic surface wave propagates in the longitudinal direction with a specified distance being provided. Then said element is provided so that its longitudinal direction is oriented to the depth of the powder. The level or the quantity of the powder is sensed by processing the received signal which varies based on the contact of the powder and the receiving electodes. For example, the sensing element, wherein thr exciting electrode 22 and the receiving electrodes 23, 24, and 25 are provided on the piezoelectric substrate 22, is provided so that its longitudinal direction is equal to the depth of the powder. A signal is generated between the electrodes 22 and 23, and the powder quantity is sensed by the outputs V01 and V02 based on the contact between the electrodes 24 and 25. |
