US2457145A - Mounting for piezoelectric crystals - Google Patents

Description

Dec. 28, 1948. F.. GRAY 2,457,145

MOUNTING FOR PIEZOELECTRIC CRYSTALS Filed Jan.L s, 194e Patented Dec. 28,v 1948 MOUNTING FOR PIEZOELECTRIC CRYSTALS Frank Gray, London, England, assignor, by mesne assignments, to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application January 45, 1946, Serial No. 639,291 In Great Britain January 23, 1945 (Cl. P11-327) 4 Claims. 1

This invention relates to mountings for piezoelectric crystals; and has for its object to provide a mounting that is of simple manufacture while ensuring a secure grip upon the crystal and attaining the correct electrical conditions.

The main features of the invention are set out severally as claims l to 4 of the statement of claim that ends this specication.

The invention will be described with reference to the accompanying drawing, in which:

Fig. 1 is a front view of a crystal holder assembly in accordance with the present invention, the cover being sectioned in order to expose the elements.

Fig. 2 is a plan view thereof, the cover again being sectioned for the purpose stated; and

Fig. 3, 4 and 5 are front view, side view and plan view respectively, on an enlarged scale, of the contact and supportingspring which appears in the earlier figures as the means carrying the crystal.

As shown in Figs. 1 and 2 of the drawing, a base-plate I of insulating material has a closetting cover 2 also of insulating material. Within the chamber defined by this base-plate I and cover 2, and mounted on the base-plate, is a quartz crystal 3. This crystal 3 consists of a square lamina 4 with electrode coatings 5 on the central portions of its main faces. The electrode coatings 5 are in electrical connection with respective terminals 6 in the form of plug-pins projecting from the under-side of the base-plate l. The present invention is concerned with the mounting of the crystal and the connection of its electrodes to the terminals.

The quartz crystal 3 is gripped cornerwise between the two spring brackets 1 of which one is shown on an enlarged scale in Figs. 3, 4 and 5. The spring brackets 1 are of L-shape with a fixing limb 8 and an upstanding limb 9, The ilxing limb 8 lies flat on the top of the base-plate I against which it is clamped by means of a nut II! screwed onto the threaded shank I I which passes through a hole I2 in the xing limb 8 and which is integral with the plug-pin 6 forming the terminal. A shake-proof washer I3 underlies the nut I0, and a rectangular stud I4 on the base-plate I fits into a corresponding rectangular recess I in the fixing limb 8 so that the spring bracket cannot turn about the shank I I. The two brackets 1 when in place hav-e their upstanding limbs 9 in parallel at a distance apart appropriate to the dimensions of the crystal 3.

Each of the upright limbs 9 is formed near its top end with a V-shaped recess I6, the angle of the V being rather less than say 85. Into these opposed recesses t the diagonally opposite corners of the square lamina 3 of quartz crystal, a gripping pressure being exerted both along the diagonal between the two brackets and also across each corner by reason of the acuteangle of the V. In consequence, the crystal is rmly held against movement in any direction within the plane of the crystal, but the springs are made of a material thin and springy enough to allow the crystal to oscillate to any frequency.

Each bracket 1 is also formed with two Wings'trips I1 .which extend up on either side of the upright limb 9 parallel but at right angles thereto, being integrally connected with the upright limb 9 at thelower ends and having their free upper ends on a level with the recess I6. The wings are bent inwards towards one another, and near their free-ends are formed with inward projections I: thus the two co-operating wings exert a gripping pressure depth-wise upon the quartz lamina 4 across its corner.

Each of the central electrode coatings 5 on the quartz crystal has two extensions I9 to adjacent corners of the lamina 4, so that however the crystal is inserted into its holder, still the two electrode coatings will make electrical connection, one with a wing I1 on one bracket 1 and the other with a wing on the other bracket. However, to make quite sure of the electrical connections, wires 20 are taken from the brackets 1 to the appropriate one of the extensions I9 at the top and bottom of' the crystal, being soldered at their ends.

What is claimed is:

1. A mounting for a piezo-electric crystal in the form of a square lamina comprising two spring strips mounted parallel to one another and each having a free end provided with a V-shaped recess, said recesses being adjacent and facing one another, said recesses being shaped so that said V has an angle slightly less than one right angle for receiving opposite corners of the crystal and for exerting a gripping pressure transverse to the diagonal between said corners.

2. A mounting for a piezo-electric crystal a-ccording to claim l further comprising two pairsl of wings, one pair being mounted on each of said strips, the wings of each pair being arranged to grip the crystal depthwise at the said opposite corners.

3. A mounting as claimed in claim 1 in which the electrical connections to electrode coatings on the faces of the crystal are made through said spring-strips.

2,457,145 3 '4 4. A mounting as -claimecl n claim 1 in which the spring strips are in the form of bracket mem- UNITED STATES PATENTS bers fixed upon a base-plate by nuts threaded Number Name Date upon bolts which are integral with terminals on 1,965,591 Gebhard July 10, 1934 the underside of the base-plate. 5 2,329,497 Washburn Sept. 14, 19413 FRANK GRAY. 2,392,429 Sykes Jan. a, 1946 2,409,838 Cress Oct. 22, 1946 REFERENCES CITED FOREIGN PATENTS mber Country'v Date Nu 10 VThe following references are of record in the 508,657 Great Britain u July 4, 1939 file of this patent:

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