| 摘要 |
PROBLEM TO BE SOLVED: To enhance the accuracy of trigger by a constitution wherein a signal, formed of a static zero level signal and drift, is used a dynamic zero level signal in a signal source and/or a signal evaluation unit. SOLUTION: A signal generated in a signal source 13 comprises a zero level signal 2 and an effective signal of acceleration pickup 7. The effective signal is amplified by an amplifer 8, and processed through a filter 9 along with the zero level signal 2 and transferred to a signal evaluation unit 3 where the signal is subjected to A/D conversion 5. At that time, a measured value 4 having a sign is produced along with a dynamic zero level signal 10 and employed for judging the following trigger process. At the unit 3, the dynamic zero level signal 10 does not have a fixed value dependent on the signal 2 for determining a zero point at the time of manufacture and the value of the signal 10 can be modified dynamically through a corrector 14 upon occurrence of disturbance or difference 1 due to drift. In this case, the signal is picked up at a predetermined time interval after A/D conversion and averaged before being compared with a previous value. |
