Patent ID: 8763461
Filing Date: 2014-07-01
Classification: G01P

Abstract:
1. An acceleration sensor device provided with an acceleration sensor which is an electrostatic induction conversion device for conversion between electric energy and kinetic energy, which comprises a conductor and an electret moving relatively to the conductor, said acceleration sensor device having: an acceleration detection unit to detect a signal corresponding to acceleration, from an AC voltage output by the acceleration sensor; a rectification unit to rectify the AC voltage; and a power supply circuit having a battery to drive circuits in the device and adapted to charge the battery with the rectified voltage as electric energy, wherein the acceleration sensor device further has: an abnormal vibration-detecting circuit which compares the rectified voltage with a preset threshold voltage to output an abnormal signal notifying an abnormality when the rectified voltage exceeds the threshold voltage, a recording circuit which is activated by the abnormal signal output by the abnormal vibration-detecting circuit as triggered by an abnormal vibration detected by the acceleration detection unit, to start recording a signal corresponding to acceleration; and which terminates the recording at a preset timing, and a determination unit to determine whether the abnormal vibration is a vibration which should be recorded, by comparing an objective vibration pattern consisting of the frequency of the signal corresponding to acceleration and the spectrum intensity corresponding to the frequency, with a preset reference vibration pattern consisting of a frequency and its corresponding spectrum intensity to determine by the comparative result whether the signal corresponding to acceleration should be recorded.