| 摘要 |
PURPOSE: To provide a bone-conduction sound oscillation detector of high sensitivity by forming a substrate and a beam part with thin films to reduce the dimensions of the whole of elements and arranging plural elements in a casing. CONSTITUTION: This detector consists of a substrate 9 made of an insulator, a semiconductor, or a conductor, insulating films 11 to 13 made of insulating material, the element part which is made of a piezoelectric body film 17 and detects the displacement or the acceleration of the beam, and a lower electrode 18 made of conductive material. Insulating films 12 and 13, an upper electrode 19, the piezoelectric body film 17, and the lower electrode 18 constitute a cantilever beam part 100. When the beam part 100 oscillates, distortion is brought about in the piezoelectric body film 17, and a voltage is generated between the upper electrode 19 and the lower electrode 18. The oscillation or the acceleration of the beam part 100 is detected by detecting this voltage. In this example, dimensions of the substrate are set to a=3mm, b=0.5mm, and c=0.4mm, and the thickness of the beam part 100 is set to 5μm. The resonance frequency of the beam is about 5kHz, and dimensions of the whole of elements are much reduced in comparison with those of conventional elements.
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