| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem wherein rise of load continues even after pressure rising time t elapses and excessive peak load occurs to give load to a piezo-stack when timing for reaching the pressure rising time t is within 0.5 T±0.1 T, because synthetic resonance period T exists in the piezo-stack and a driving body. SOLUTION: When the pressure rising time from the start of charging to the reach of target charging voltage of the piezo-stack is t and the synthetic resonance period of the piezo-stack and the driving body is T, the pressure rising time t is set to satisfy the relation of 0.6 T≤t. Consequently, it is possible to avoid the inconvenience that the timing for ending charging and pressure rising of the piezo-stack and the timing for making load gradient the maximum value by the synthetic resonance period T are overlapped and make pressure rising gradient just before reaching the pressure rising time t gentle. As a result, peak load and dip load generated in the piezo-stack are suppressed and reliability of the piezo-stack for a long time is improved. COPYRIGHT: (C)2007,JPO&INPIT
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