| 摘要 |
<p>PURPOSE:To always correctly control the displacement of a piezoelectric element even if the elements are irregular and changed at ageing by providing a displacement sensor for detecting the displacement at the time of applying the voltage of a laminate in the laminate. CONSTITUTION:In a laminated piezoelectric element 1 in which many piezoelectric elements 1a and electrode plates 1b are stacked to form a laminate, a power source is connected to the laminate to apply a voltage thereto to deform the elements 1a, a displacement sensor 6 for detecting a displacement at the time of applying a voltage to the laminate is provided in the laminate. The sensor is, for example, formed by attaching the laminate to a center bar passing axially through the laminate and attaching it to a cover for coating the laminate. The sensor uses, for example, a strain gauge or a gap sensor. For instance, the part of the rod 36 of the par 3 is formed flatly, and a strain gauge 6 in which its electric resistance will vary when it is deformed is bonded thereto.</p> |
