To provide a detector which can detect an angular acceleration and which is small and low-cost.
A mass part 20 which is supported on a board 1 by a fixation part 22 and which can be turned fine around a shaft 200 is formed. In addition, a turned- down beam which is connected to the mass part 20 by a connection point 300 and which is composed of a first beam 301, a turned-down part 31 and a second beam 302 is formed. The turned-down beam can be vibrated in the y-axis direction while the connection point 300 to the mass part 20 and a turned-down-beam fixation part 32 are used as fulcrums. Comb-teeth electrodes are formed at the turned-down part 31 as well as at an exciting electrode 33 and a detecting electrode 34 which are fixed to a boatd face 1a. An external circuit is connected. The resonance frequency of the turned-down beam is detected. When an angular acceleration around the shaft 200 is applied to the mass part 20, a torque is generated, and the mass part 20 is turned fine around the shaft 200. Thereby, the connection point 300 is moved, the interval 11 between the first beam 301 and the second beam 302 is increased or decreased, and the resonance frequency of the turned-down beam is changed. On the basis of a change in the resonance frequency of the turned-down beam, the angular acceleration, around the shaft 200, applied to the mass part 20 can be detected.
NONOMURA YUTAKA
FUJIYOSHI MOTOHIRO
FUJITSUKA TOKUO
MIZUNO KENTAROU
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