| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent an erroneous detection due to a popcorn noise, external instantaneous shock or electric impulse noise. SOLUTION: Output current from a piezoelectric element 1 is converted by a current voltage converter 2 into a voltage signal and the voltage signal is amplified by a wide band amplifier 3 and inputted to a frequency analyzer 4. Thus, the frequency analyzer 4 analyzes the frequency of the current output of the piezoelectric element 1 and outputs detection signal in the case that a high frequency component corresponding to the popcorn noise and the like is not included even if a frequency component corresponding to human body motion is included. Therefore, a human body is accurately detected without being affected by popcorn noise and the like and erroneous detection can be prevented.</p> |
