| 摘要 |
PURPOSE:To improve the sealing property and conductivity of a metallic cap which is externally fitted to end face electrodes installed to both end parts of a cylindrical case in which a piezoelectric element is contained, by making the outer diameter of the end face electrode a little larger than the inner diameter of the metallic cap and closely putting the metallic cap on the electrode with pressure. CONSTITUTION:A piezoelectric element 4 is formed by installing electrodes 2 and 3 facing each other to both surfaces of a rectangular piezo-substrate 1 and the substrate 1 is contained in a cylindrical case 11. Annular end face electrodes 12 are formed at both end parts of the case 11. The outer diameter D1 of the outer periphery 12b of the electrode 12 is set a little larger than the inner diameter D2 of the annular peripheral wall of a metallic cap 13 which is externally fitted to the outer periphery section 12b of the electrode 12 and the annular peripheral wall 13b is closely fitted to the outer periphery part 12b with pressure utilizing its elasticity. Therefore, a completely airtight condition is maintained between the end face electrode 12 and metallic cap 13 and the conductivity between the electrode 12 and cap 13 is ensured. Moreover, the pull-out strength and reliability are also improved. |
