| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a water level sensor capable of detecting a water level and the fluctuation of the water level, and acquiring power for transmitting water level information by radio transmission in the detection of water level. <P>SOLUTION: The water level sensor 50 has a structure in which an air hole 21 is formed at the upper part, a water permeating hole 22 is formed at the lower part of a cylindrical member 11, and they are formed in a vertical posture; and a plurality of power generation units 16 are provided at predetermined interval in a vertical direction in its inside. The sensor 50 causes the power generation units to generate power in response to a change in a water level in the cylindrical member 11, and a signal transmitter 14 to transmit a voltage signal in the power generation while utilizing the power. The power generation units 16 have bending displaceable piezoelectric elements 31, springs 32 for bending the piezoelectric elements 31, permanent magnets 33 attached on the piezoelectric elements 31, water-proof cases 34 for housing these component, floats 27 provided outside the cases 34, and weights 28 provided outside the cases to the permanent magnet 33 so as to be closable to and separable from the magnet. <P>COPYRIGHT: (C)2008,JPO&INPIT |
