| 摘要 |
PURPOSE:To enable a detection head to be compact by allowing both edges of a detection duct to contact each other through a diaphragm of a sound source while is provided at a barrier wall and a space which contacts the surface and rear of the diaphragm to be operated as two containers. CONSTITUTION:Both edges of a detection duct 10 are allowed to contact each other through a diaphragm 12 and spaces 111 and 112 which contact the surface are rear of the diaphragm 12 operate as two containers acoustically, thus achieving an acoustic bridge as a whole. A sinusoidal wave voltage with an angular frequency of w is fed from an external oscillator to a piezoelectric element 12' through a conductor 21 and a terminal 20, volume change is produced differentially at the spaces 111 and 112 due to vibration of the diaphragm 12 and a vibrational flow with an angular frequency of w having a velocity of u(t) (t: time) is produced within the duct 10. Then, sound pressure at points Q and Q' directly below the inside of the duct 10 is detected by microphones 14 and 14', it is sent to an external signal-processing circuit through conductors 19 and 19', and phase difference and amplitude change between two signals are detected, thus obtaining a rotary angular velocity OMEGA of a detection head around a vertical axis z - z'. |
