GB488564A - Means for supporting mechanically vibrating elements such as piezo electric crystals - Google Patents

Abstract

488,564. Piezo - electric crystals; electromagnetic resonators. STANDARD TELEPHONES & CABLES, Ltd. Jan. 8, 1937, No. 615. Convention date, Jan. 30, 1936. [Classes 40 (iii) and 40 (v)] Undesired oscillations in crystals and other resonators are damped out by means of soft metal. In crystals cut parallel to the electric axis, so that the frequency is independent of temperature for transverse vibrations propagated normally to the crystal-face, instability of resonance, due to coupling between the transverse vibrations and longitudinal vibrations propagated parallel to the face, is prevented by damping out the longitudinal vibrations with soft metal in such a way as to prevent the formation of longitudinal standing waves by reflection. In the arrangement shown in Fig. 4, the crystal 7 has bevelled edges engaging the corresponding edges of a screw-threaded ring 9 which, with the base 2, forms a cup-shaped receptacle into which the crystal is pressed by an adjustable spring 5 acting through a disc 6. The bevelled edge of the ring 9 is coated with a soft metal such as tin or lead for damping out the undesired vibrations. Undesired oscillations in metallic bars may be similarly damped with soft metal. The Specification as open to inspection under Sect. 91 comprises also the following subject - matter. A strip - shaped crystal 20, Fig. 5 (Cancelled), may be supported by pins 16 which project respectively from a blade 14, having a bend 21 for purposes of adjustment, and from a troughshaped plate 4 provided with a flat at 5. The undesired vibrations are damped by projections carried by springs 17 and adjacent to the holding pins 16. Packing 13 may be provided to steady the crystal during transport, and the assembly is enclosed in a glass tube 1 with water-tight end caps. In a modification, Fig. 7 (Cancelled, not shown), the crystal may have two pairs of electrodes with corresponding terminals, and the spring 24, Fig. 9 (Cancelled), carrying one of the pins 16 that support the crystal, can be adjusted by means of the screw for positioning the crystal. This subject-matter does not appear in the Specification as accepted.