| 摘要 |
PROBLEM TO BE SOLVED: To prevent a piezoelectric element from brought into contact with its case to avoid producing noises and suppress the flexure of a piezoelectric element to below a breakdown limit. SOLUTION: A ring- or strip-like elastic piece 15 is fitted around the vibration node of a piezoelectric element and retained by a case 14, a board 12, etc., at its surrounding to hold the piezoelectric element with spaces from the case 14 and the board 12. This enables the clearance between a piezoelectric ceramic element and the case to be reduced to about 0.3 mm, as compared with about 1.0 mm which is required in prior art, and enables stably to hold the clearance and hence prevent the piezoelectric ceramic element from contacting the case and producing noises due to dimming signals.
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