US2504493A - Piezoelectric cell - Google Patents

Description

April 8, 1950 M. BROWNSHIELD 2,504,493

PIEZOELECTRIC CELL Filed May 21, 1945 2 Sheets-Sheet l A ril 18, 195 M. L. BROWNSHIELD PIEZOELECTRIC CELL Filed May 21, 1945 Ll/y 2 Sheets-Sheet 2 wil 14 INVENTOR Milzfon/ fiz'awms'kabld ATTORNEY 5 Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE PIEZOELECTRIC CELL Milton L. Brownshield, Dobbs Ferry, N. Y.

Application May 21, 1945, Serial No. 594,906

25 Claims. 1

It is among the objects of the invention to provide a piezo-electric cell made up of relatively inexpensive and rugged parts, easily assembled, inherently to confine the crystal in fluid tight relation, and which necessitates no departure whatsoever from externally standard dimensions useful in equipment or this type.

In the accompanyin drawings in which are shown one or more of various possible embodiments of the several features of the invention:

Fig. 1 is a dropped perspective view of the elements making up the unit.

Fig. 2 is a perspective view of the complete assembly.

Fig. 3 is a view of the longitudinal cross-section taken on line 3-3 of Fig. 2.

Fig. 4 is a plan of the casing member with parts broken away.

Fig. 5 is a view similar to Fig. 4 of the face of the cover member.

Fig. 6 is a fragmentary section view taken on line 6-6 of Fig. 2.

Fig. '7 is a view similar to Fig. 6 of a modification and Fig. a is a perspective view of the assembly with the cover slightly displaced, and partly broken away.

Referring now to the drawings the piezoelectric cell unit comprises an insulating casing l0, preferably a rectangular casing of suitable insulating material. The casing is desirably molded from a powder of mixed mica and glass bonded together, which has the virtue of not absorbing moisture. The casing has a cavity H therein, preferably a generally square cavity enlarged by shallow bays ll extending symmetrically the major part of the lengths of the respective sides. The bottom of the cavity H has a contact plate l2 therein, to which the composition 01' the casing may be bonded in the molding operation. To plate I2 is electrically connected the wire I3 embedded in the composition, the end of the wire extending in a loop it about a groove M in the corresponding terminal, desirably a prong l5 protruding from thecasing, and embedded therein.

Lodged in the cavity H is a more or less conventional piezo-electric crystal Hi of quartz or the like, which is interposed between two conventional electrode plates '1'! and ill, the thickness at the corners of which is enlarged at the inner faces thereof as at is for contact only with the corner portions of the crystal.

The cover 20 of the casing is desirably of the same composition and of the same contour as form groove 34 in the face of the cover.

the casing itself. The inner face of the cover contacts the rim 2! of the casing and ridges 22 along the inner face of said cover are encompassed by said rim 2| and engage a gasket 23 preferably of rubber, natural or synthetic, seated in the circular depression 24 in casing Ill.

The cover has a contact plate 25 at its inner face, similar to plate I2 and preferably bonded in place, with clips 26 unitary therewith, extending over the lateral edges of a bowed leaf spring 21 the rounded ends 28 of which engage the electrode l8. A wire 29 in engagement with the contact plate 25 is embedded in the material of the cover and is turned outward as a pin 30 protruding from the face of the cover and extending into a notch 3| in the outer wall of the casing I0 adjacent to the second or companion terminal or prong 32. Electrical contact is es tablished by filling the groove 3| with solder 3| to bond the wire 29 to the prong 32.

To maintain the structure in assembled relation, clamp means is preferably provided, which in a desirable embodiment is in the form of a spider 33 countersunk in a corresponding cruci- Ports, preferably rectangular ports 35 extend clear through the thickness of the casing and corre-- sponding registering ports 35' through the cover assembly, at the exterior of the gasket 23 and preferably, as shown, near the corners of the rec tangular structure. The downturned legs 38 o! the spider extend through said ports 35', 35 and their ends are obliquely inturned to form toes 31. As will be readily seen, the spider clamp can be snapped in place, so that each toe 31 will ride along the inner wall of the corresponding port 35 and then snap at its extremity into contact with the base or the casing. Desirably, the casing has wells '38 in the lower face thereof that accommodate the toes, so that do not protrude beyond the lower face or the casing and their end edges 38 react against the bases or the respective wells 38. The spider clamp thus presses the cover against the casing and thereby forces the r' ridges 22 of the cover inward into the gasket 23 as shown, and maintains the spring 21 under compression resiliently to hold the parts in assembled relation.

Thus in the assembly, access of moisture to the crystal is precluded since the active parts in cluding the crystal it, its electrodes 11 and i8 and the spring 21 are completely encased. The gasket 23 thus pressed between casing It and cover 20 precludes entry of moisture at the Joint between said parts.

The clamp can in no wise interfere with the efficacy of the liquid tight seal and exerts efEec-- tive and uniform compression upon the gasket by reason of the fact it is at the exterior and encompasses the gasket.

The various clamp elements are completely within the boundaries of the closed casing and do not protrude therebeyond so that the cell lends itself readily for use in installations where space is limited.

In the embodiment of Fig. '7 is a slight modification of that of Fig. 6, in that the spider legs 36- instead of being straight as in Fig. 6 are transversely curved as at 40, thereby to add resiliency to the clamp.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A piezo-electric cell, comprising an insulating casing having a cover, electrode plates with the crystal interposed therebetween and housed in a corresponding cavity in said casing, spring means interposed between said cover and one of the electrodes, pressing against the crystal, and a spider externally of the cavity afiixing and pressing the cover upon the casing, said cell having terminals electrically connected to the respective electrodes.

2. A piezo-electric cell, comprising a casing having a cavity therein, a contact plate in said cavity, a terminal at the exterior of said casing and an electrical connection between said plate and said terminal, electrode plates, and an interposed crystal in said cavity with the inner of said electrodes in contact with said contact plate, a cover having a contact plate at its inner face, a spring inter-posed between said cover contact plate and the outer electrode, and a metal pin connected to said cover contact plate and extending into a corresponding passage in said casing, said casing having a second terminal connected to said pin and means securing the cover to the case.

3. A piezo-electric cell, comprising an insulating casing, having a pair of terminals, a chamber in said casing having a contact plate lodged therein, means in said casing electrically connecting said plate to one of said terminals, a pair of electrode plates with an interposed crystal lodged in said chamber, an insulating cover closing said chamber, said cover having a contact plate therein, a spring interposed between said plate and one of the electrodes and a wire within said cover extending from the contact plate thereof outward with its extremity electrically bonded to the other terminal on the casing.

4. A piezo-electric cell, comprisin an insulating casing having a, chamber therein and having terminals, a contact plate in said chamber, a wire embedded in said chamber and electrically connecting said plate to one of said terminals, a .pair of electrodes having a crystal interposed therebetween and lodged in said chamber with the inner electrode engaging said contact plate, a gasket at the outer face of said chamber, a cover having a sealing ridge, said cover having a contact plate therein, a spring interposed between said cover contact plate and the other terminal, a wire embedded in said cover and connected to the contact plate thereof, said wire having a protruding end extending into a corresponding port in said chamber and electrically bonded to the other terminal of the casing and means maintaining the cover affixed, with the sealing ridge thereof pressed against the gasket.

5. A piezo-electric cell, comprising an insulating casing having a chamber therein and having terminals, a contact plate in said chamber, a wire embedded in said chamber and electrically connecting said plate to one of said terminals, a pair of electrodes having a crystal interposed there- F between and lodged in said chamber with the inner electrode engaging said plate, a gasket at the outer face of said chamber, a cover having a sealing ridge, said cover having a contact plate therein, a spring interposed between said plate and the other terminal, a wire embedded in said cover and connected to the contact plate thereof, said wire having a protruding end extending into a corresponding port in said chamber and electrically bonded to the other terminal of the casing and clamp means wholly at the exterior of the cavity, maintaining the cover against the casing, with the sealing ridge compressing the gasket.

6. A piezo-electric cell, comprising an insulating casing having terminals, an insulating coveiw therefor, a pair of electrodes with an interposed crystal lodged in a corresponding chamber in said casing, contact means in said casing and said cover respectively, engaged by the respective electrodes, conducting means embedded in the re spective casing and cover and leading to the respective terminals and clamp means at the exterior of said casing and extending across the thickness of the closed casing and maintaining the cover pressed against the casing.

7. A piezo-electric cell, comprising an insulating casing having terminals, an insulating cover therefor, a pair of electrodes with an interposed crystal lodged in a corresponding chamber in said casing, contact plates in said casing and cover respectively, engaged by the respective electrodes, conductors embedded in the respective casing and cover and leading to the respective terminals, clamp means at the exterior and extending across the thickness of the covered casing and maintaining the cover pressed against the chamber, and gasket means interposed between. the casing and the cover, said casing having an outer rim encompassing said gasket means, said cover having ridges pressed into the gasket.

8. A piezo-electric cell, comprising a casing, a cover therefor, a pair of electrodes with an interposed crystal lodged in the casing, said casing and cover having contact plates engaging the respec tive electrodes, said casing having terminals, electrical connectors embedded in the covered casing and leading from the contact plates to the respective terminals, a gasket in the end of the easing wall and near the outer rim thereof, said cover having a ridge engaging said gasket, registering ports through the cover and the casing and at a region exteriorly of the gasket and metal clamp means through the respective registering ports and exerting pressure against the face of the casing and cover respectively, and compressing the cover ridge into the gasket.

9. The combination recited in claim 8, in which the clamp means comprises a unitary spider with the outer part of the legs thereof extending through said ports and with hooked extremities pressing upward against the casing.

18. A piezoelectric cell. comprisin an insulatins cas n havin a chamber herein, a cover therefor, con act plat s at epn siie inner faces of the closed cas n electrodes with an int rvccins cry tal interposed betwe n sa d plates, termin le on the casi electrical eonnecters respectively in the caslng'and the. cover and ex nding between the respective te mi als nd the corresponding contact plates, clamp means comprising a spider having the legs thereof countersunk i corr spondin depressio s a ne ace f the closed casing, the outer parts of said legs ext din through po ts transv rsely throu h h thickness of the closed casing, the extremities of said legs being lodged in depressions in the casing structure and turned inward to press upward against the casing. I

11. The combination recited in claim 10, in which spring means within the closed casing resiliently resists the clamping action of the spider and resiliently exerts pressure upon the crystal and serves as an electric connection between the crystal and one of the contact plates.

12. The combination recited in claim 10, in which a gasket is lodged in a corresponding cavity at the boundary between the casing and the cover and ridge means unitary with one of said elements maintains the gasket under compression due to the pressure exerted by said clamp.

13. A piezo-electric cell, comprising an insulating casing structure, having a crystal accommodating chamber therein and an insulating cover, contact plates in the casing and cover respectively, terminals on the casing, electrical connectors in the casing structure between the contact plates and the respective terminals, resilient means interposed between the easing and the cover and a clamp to maintain the parts assembled and the resilient means under stress, said clamp comprising a unitary spider structure accommodated the extremities of said legs being reversely bent and being lodged in corresponding wells in the base of said casing and pressing against the casmg.

14. The combination recited in claim 13, in which the resilient means comprises a gasket, the outer edge of which is encompassed by a pcripheral rim on the casing and in which the cover has a grooved ridge pressing into said gasket and in which the ports accommodating the clamp are outside of said gasket.

15. A piezo-electric cell comprising a generally rectangular casing structure, comprising a casing and a cover closing the same, a pair of generally rectangular electrodes with a corresponding crystal interposed therebetween and lodged in said casing, contact plates in parallel relation in the casing cavity and the inner face of the cover respectively, a leaf spring interposed between the cover and one of the electrodes, wires embedded in the casing structure and connecting from the contact plates to the respective terminals, the casing having a narrow ridge rising from the outer part of its rim, a gasket against said rim and encompassed by said ridge, said cover having circular ribs engaging said gasket and clamp means for maintaining the cover pressed against the casing, said clamp means comprising a spring metal spider, the arms of which are lodged in a corresponding groove in the outer face of the cover to lie substantially flush therewith, the

outer part of the arms extending transversely of the casing structure through corresponding ports near the corners of the rectangular casing at the exterior of the gasket, the extremities of said arms being reversely bent and being lodged in corresponding wells in the lower face of the easing and reacting against the bases of said wells.

15. In a piezo-electric cell, the combination of a casing having terminal prongs, a contact plate in the base of said casing, a wire connector embedded and connecting said, plate to one of said prongs, said casing having a cover with a contact plate in the inner face thereof, a wire conhector engaging said plate and embedded in said cover, said wire having an outwardly extending end, said casing having a groove at the exterior thereof, at the other terminal prong, and accommodating said wire end, said wire end being soldered in place for electrical connection to said other terminal prong. i

17. In a piezo-electric cell, the combination of an insulating casing, a cover therefor, a pair of electrodes with an intervening crystal in said casing, terminals connected to the respective electrodes, a clamp in the form of a spider lodged in a corresponding depression in the face of the cover, said spider having legs extending through corresponding ports in the cover and casing, reversely bent toes at the ends of said legs, said ends and said toes being lodged in corresponding wells in the base of the cover, the toes pressing against the base of said wells.

18. The combination recited in claim 17, in which the legs are straight.

19. The combination recited in claim 1'7, in which the legs are bowed.

20. A piezo-electric cell, comprising an insulating casing having a cover, electrode plates with the crystal interposed therebetween and housed in a corresponding cavity in said casing, spring means interposed between said cover and one of the electrodes, pressing against the crystal and means externally of the cavity afiixing and pressing the cover upon the casing, said cell having terminals electrically connected to the respective electrodes, said casing and cover being molded of an insulating plastic material and conductors respectively molded permanently in the casing and cover serving as the electrical connections between said terminals and electrodes.

21. A piezo-electric cell, comprising an insulating casing having a cover, electrode plates with the crystal interposed therebetween and housed in a corresponding cavity in said casing, spring means interposed between said cover and one of the electrodes, pressing against the crystal and means externally of the cavity afiixing and pressing the cover upon the casing, said cell having terminals electrically connected to the respective electrodes, said last mentioned means including a metal clip, said casing and cover having recesses receiving said clip, said recesses extending entirely through the assembled casing and cover adjacent the outside thereof.

22. A piezo-crystal assembly comprising a boxlike housing and cover, both of insulation material, a pieZo-crystal and cooperating electrodes within the cavity of said housing and a moistureproof gasket between said cover and said housing, said housing having a recess receiving said gasket and said cover having ribs compressing said gasket in said recess and spring clip means having legs extending transversely through said housing and cover holding said crystal, electrodes,

gasket and cover tightly together.

23. A holder for plate crystals for tuning radio sets to operate at a pre-selected radio frequency comprising a recessed insulating casing, a crystal plate and two electrode plates, one on each side of said crystal plate, a cover for said casing and an external spring clip to clamp said casing, crystal plate, electrode plates and cover together, said spring clip having a plurality of legs extending through the corners of said casing and said cover.

24. A casing for crystals and the like comprising, a body portion, a cover fitted over and closing the body portion, a spring clip extending over the top of the cover and urging the cover toward the body portion, said clip having a plurality of arm portions extending downwardly on opposite corners of the body portion, the body portion having recesses presenting shoulders located below the cover in the bottom of the casin with which the ends of the arm portions engage. 2o

25. A casing for crystals as called for in claim 24, wherein the clip has a central spider portion urged resiliently against the top of the cover to force the cover toward the body portion, and wherein the arm portions of the clip each have an inturned end portion in engagement with a recess in the body portion.

MILTON L. BROWNSHIELD.

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

UNITED STATES PATENTS Number Name Date 2,329,321 Bach Sept. 14, 1943 2,361,343 Woodmark Oct. 24, 1944 2,404,445 Kuenstler July 23, 1946 2,416,876 Kuenstler Mar. 4, 1947 2,434,043 Kershaw Jan. 6, 1948

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