Both Directivity and Nondirectivity Accelerometer for HDD

Abstract

This paper describes a piezoelectric accelerometer that has unique and simple structure. This newly developed accelerometer is suitable for HDD (Hard Disk Drive) that is mounted in PC (Personal Computer). Piezoelectric ceramic is divided into two, therefore we can use the differential amplitude circuit. So, it realizes high S/N ratio, 10 dB higher than the conventional accelerometer in spite of the same size package. By using rotation of the polarized direction and the asymmetric division of the piezoelectric ceramic, we realize the nondirectivity accelerometer for shock detection and directivity accelerometer for rotational vibration detection. Our newly accelerometer has the smallest size package of 3.2*2.0*0.8 (mm) for shock detection and high sensitivity of 8 (mV/G) for rotational vibration detection.