| 摘要 |
PURPOSE:To obtain a low cost sensor by rendering the output from a piezoelectric element a sinusoidal wave with an accurate period. CONSTITUTION:A piezoelectric vibration sensor is provided with body frames 11 and 12 having a pair of protectors 11a and 12a and mounted to an apparatus to be measured, a vibrating plate 13 disposed between the protectors 11a and 12a in spaces A and A and supported by the frames 11 and 12 like a cantilever, a weight 14 mounted to the free end of the vibrating plate 13 by spot welding, a thin-diskwise or rectangular piezoelectric element 1 made of barium titanate ceramics and adhered to the root of a surface of the vibrating plate 13 and the like. By determining the length L between the center of the weight 14 and the fixed end 13a of the vibrating plate 13, for example, on 35-40mm, the natural period of a vibrator B composed of the vibrating plate 13, weight 14 and the element 1 is made larger than the period of the apparatus to be measured and the vibrator B conducts a harmonic vibration (since wave) to enable a vibrations period to be always measured.
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