Ultrasonic Phased-Array Sensor Using PZT Thin Film and Three-Dimensional Object Detection Using BBD Combined with BBD Delay Circuit

Arrayed ultrasonic microsensors using piezoelectric PZT (Pb(Zr,Ti)O3) thin lms on micromachined silicon diaphragms have been fabricated and combined with BBD (Backet Brigade Device) for signal processing. The ultrasonic sensors are designed to compose an electrical phased array for three-dimensional object detection in air. The resonant frequencies of the elements were scattered in the error range of 12 % and the objects could not be detected due to the beat in the sum of delayed element waveforms. Each element has been tuned by adequate poling less than 10 V to make its resonant frequency equal to a center value. The frequency scattering was reduced within the range of 2 % and the tuned array could give the objects by summing up of the delayed signals. Three-dimensional object detection has been demonstrated using the tuned sensor combined with the BBD delay circuit.4 KCI Citation Count: 0