US2434903A

US2434903A - Piezoelectric crystal mounting

Info

Publication number: US2434903A
Application number: US564418A
Authority: US
Inventors: Samuel A Bokovoy; Henry W N Hawk
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC; Federal Telephone and Radio Corp
Priority date: 1944-11-21
Filing date: 1944-11-21
Publication date: 1948-01-27
Anticipated expiration: 1965-01-27
Also published as: BE462051A; CH256674A

Description

27, '1948. s. A. BOKOVOY ET AL PIEZO-ELECTRIC CRYSTAL MOUNTING Filed Nov. '21, 1944 INVENTORS SAMUfl A. Jammy 'f/f/WP) n /V. AMW/r A TTDPA/EY Patented Jan. 27, 1948 PI EZOELECTRIO CRYSTAL 'MOUNTING Samuel A. Bokovoy, Verona, and Henry W. N.

Hawk, East Orange, N.

Telephone and Radio J assignors to Federal Corporation, New York,

N. Y.,-a corporation of Delaware Application November 21, 1944,Serial No."564,4'18

8 Claims.

v1 This invention relates to mountings for piezoelectric crystals'and in particular to mountings for crystals of the type wherein the energizing electrodes are plated directly on the crystal surface in distinction to that clas wherein the crystalsvibrate between two fixed electrodes,

The main object of the invention is to devise a crystal holder or mounting which by reason of its simple construction and small number of parts results in a'conside-rable saving of both material and production costs as compared with holders of the prior art.

Other objects and advantages will become apparentand the invention will be best understood by reference to the following detailed description and accompanying drawing wherein Fig. 1 is a perspective drawing of a crystal holder showing one embodiment of the invention,

I Fig. 2 is a perspective drawing showing a crystal holder in accordance with a second embodiment of the invention.

Similar elements appearing on the various drawings have been given the same reference characters.

Referring to Fig. 1, the numeral l represents a base which may be molded from Bakelite or some othersuitable material. Molded integrally with the base I are two

metal inserts

2 and 3. The central portions of the inserts are roughened, as for example by knurling, whereby a firmer bond between the inserts and the Bakelite is obtained. The

upper portions

4 and 5 of the inserts serve as supports for the piezo-electric crystal 6 and also make electrical contact with the crystal electrodes 1 and 8. The lower portions 9 and I0 serve as terminals which may be plugged into a socket for mounting the crystal holder. Elements H and I2 are spring clips made of a material such as Phosphor bronze. The lower portion l3 of the clips takes the form of a slotted cylinder having an inside diameter which is slightly smaller than the diameter of the

supports

4 or 5. This cylinder is pressed over the support and may be soldered, spot welded, or otherwise fixed in place. The clips H and 12 have a side extension I4 which prevents end motion of the crystal after it has been placed in the mounting.

The crystal 6 is preferably rectangular in shape and of a thickness depending on the desired frequency. The crystal electrodes 1 and 8 are plated on the opposite faces of the crystal in such a manner that a small area at one end of each crystal remains unplated. The plated area at theend ofone crystal face isoppos'ite the unplated area of the other crystal 'face. This method of plating is employed in order that the electrodes will not'be short circuited by thesupport and spring clip. In the figures the thickness of the plating is shown greatlyexagg-erate'd. In reality the plating is onlya few thousandths of an inch thick.

The cover' I 6 may also 'be molded from Bakelite or the like, and is designed to fit snugly over the base I to which it may be hermetically sealed.

Fig. 2 shows a modification'ot Fig. 1 'inwhich the crystal electrodes may be plated over the entire surface of each crystal face. -In-this embodiment of our invention'an insulating sleeve I5 is slipped over the supports A and 5 in order that the crystal electrodes will not be short oncuited by the supports and the spring clips. Electrical contact with the crystal electrodes is in this case made with the spring clips II and I2 rather than with the

supports

4 and 5 as in Fig. 1.

Other modifications of our invention will occur to those skilled in the art, such as for example, covering the spring clips with an'in'sulating material and omitting the insulating sleeve from the supports. 7

Another modification would be the employment of a support rod made in its entirety of an insulating material such as'for example, a small Bakelite rod. The rod could be pressed into a hole drilled into the end of the metal insert.

Having thus described our invention we claim:

1. A piezo-electric crystal assembly comprising a base carrying two metal risers extending therethrough and having portions serving respectively as a terminal, as a support for the crystal and as a pressure element therefor, the support and pressure element being in opposed relation for the reception of the crystal therebetween, a crystal having opposite electrodes substantially coextensive with the faces thereof and positioned between the support and the pressure element and insulation interposed between one of said opposed portions and the electrode.

2. A piezo-electric crystal assembly comprising a base carrying two metal risers extending therethrough and having portions serving respectively as a terminal, as a support for the crystal and as a pressure element therefor, the support and pressure element being in opposed relation for the reception of the crystal therebetween, a crystal having opposite electrodes substantially coextensive with the faces thereof and positioned between the support and the pressure element,

3 insulation on one of the opposed portions and an insulating cover fitted to the base and enclosing the crystal.

3. A mounting for piezo-electric crystals having surface electrodes comprising a base carrying two metal risers extending therethrough and each having portions serving respectively as a terminal, as a support for the crystal and. as a pressure element therefor, the support and pressure element being in opposed relation for the reception of the crystal therebetween and insulation interposed between one of said opposed portions and the crystal.

4. A mounting for piezo-electric crystals having surface electrodes comprising a base of insulating material having two parallel metal risers molded therein and projecting from opposite sides of the base, each of the risers having portions serving respectively as a terminal, as a support for the crystal and as a resilient pressure element therefor, the support and pressure element beingin opposed relation for the reception of the crystal therebetween, insulation interposed between one of said opposed portions and the crystal and a housing cover member of insulating material fitted to the base and enclosing the crystal.

5. A mounting for a piezo-electric crystal having plated electrodes comprising a base, two metallic inserts extending through the base each having a crystal supporting portion mounted in said base in such a manner as to project substantially at right angles thereto and so as to be substantially parallel to one another, a spring clip mounted on each of said supporting portions and making electrical contact with a plated electrode of said crystal on the side opposite that side of said crystal which is in mechanical contact with the supporting portion bearing said clip, means for preventing an electrical short circuit between said plated electrodes, said means including a covering of insulating material surrounding that portion of each metallic insert which comes in contact with the other plated surface of said crystal whereby conductive contact between said insert and a plated electrode of said crystal is prevented.

6. A mounting for a piezo-electric crystal comprising a base, two terminal members supported by said basesubstantially at right angles thereto,

a crystal supporting member integral with each of said terminal members, and a spring clip mounted upon each of said supporting members, said crystal being held between each support and the spring clip mounted thereupon, said support and said clip making mechanical contact with opposite sides of said crystal.

7. A mounting for a piezo-electric crystal having plated electrodes, comprising a base, two metallic inserts each integrally formed with a terminal portion and a crystal supporting portion mounted in said base and projecting from opposite sides thereof, an insulating sleeve surrounding each supporting portion, and a spring clip mounted upon each insert for holding one end of a piezo-electric crystal against said crystal supporting portion and for making electrical contact with a plated electrode.

8. In combination, a piezo-electric crystal having electrodes plated on its opposite faces, a mounting for said crystal comprising a base member, two metallic inserts each having a terminal portion and a crystal supporting portion fastened to said base and extending therethrough, so as to project therefrom substantially at right angles, said supporting portions extending substantially parallel to one another, a spring clip in electrical contact with each insert for holding one end of said crystal against a supporting portion and means for preventing an electrical short circuit between said plated electrodes, said lastmentioned means including an insulating sleeve covering that part of said supporting portion which comes into mechanical contact with one of said plated electrodes.

SAMUEL A. BOKOVOY. HENRY W. N. HAWK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Lutzens Dec. 15, 1942