| 摘要 |
918,652. Piezo-electric crystals. EBAUCHES S.A. July 3, 1961 [July 6, 1960], No. 23975/61. Class 40 (8). A piezo-electric thicknessshear resonator has electrodes disposed parallel to the major faces of the crystal section, the electrodes having a central unmetallized portion. In the example shown, a quartz disc, of e.g. AT cut, is provided with annular electrodes 2 having central unmetallized portions 3. Both the resistance and the inductance of the crystal increase as the unmetallized area increases, but since the ratio L/R increases also, there is an improvement in the Q of the crystal. Unmetallized marginal portions 4, 5 are left for the attachment of clips. In a further example (Figs. 3, 4, not shown), the unmetallized area is in the form of a rectangle with sides parallel to the X and Z<SP>1</SP> axes. The disc may have plane parallel faces with bevelled edges, or may be lenticular in section. |
