| 摘要 |
PROBLEM TO BE SOLVED: To reduce errors generated by the stress, which is applied on a piezoelectric ceramic substrate caused by the difference in respective linear-expansion coefficients of the piezoelectric ceramic substrate, a bonding agent layer and a metal diaphragm. SOLUTION: A metal diaphragm 6 is bonded to the back surface side of a piezoelectric ceramic substrates 5 through a bonding agent layer, and a weight member W is fixed to the metal diaphragm 6. The linear-expansion coefficient of the bonding agent layer is larger than the linear-expansion coefficient of the piezoelectric ceramic substrate and the linear-expansion coefficient of the metal diaphragm 6. As the metal diaphragm 6, the diaphragm made of metal, whose linear-expansion coefficient is smaller than the linear-expansion coefficient of the piezoelectric ceramic substrate 5, is used so that the apparent linear- expansion coefficient of the metal diaphragm 6 under the state, wherein the shearing stress generated by the thermal expansion of the bonding agent layer acts, becomes the value approximate to the linear-expansion coefficient of the piezoelectric ceramic substrate 5. |
