US2418491A

US2418491A - Piezo crystal unit assembly

Info

Publication number: US2418491A
Application number: US597654A
Authority: US
Inventors: George S Wachtman
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-06-05
Filing date: 1945-06-05
Publication date: 1947-04-08
Anticipated expiration: 1964-04-08

Description

April 1947- s. s. WACHTMAN 2,418,491

PIEZO CRYSTAL UNIT ASSEMBLY Filed June 5, 1945 2 Sheets-Sheet 1 Patented Apr. 8, 1947 UNITED STATES PATENT OFFICE 9 Claims. 1

My invention relates broadly to piezo electric crystal apparatus and more particularly to an improved construction of piezo crystal unit assembly.

One of the objects of my invention is to provide a construction of piezo electric crystal unit assembly which is relatively inexpensive for mass production and which has a high electrical e'fllciency.

Another object of my invention is to provide an improved construction of piezo electriccrystal unit assembly having a minimum number or parts and low electrical capacity for efllcient operation in piezo electric crystal control and oscillator circuits.

Still another object of my invention is to provide a construction of piezo electric crystal unit assembly which is extremely small in size and which may be readily detachably mounted inua circuit terminal assembly of low cost.

Still another object of my invention is to provide a construction of relatively flat holder for a piezo electric crystal of a depth which is only slightly greater than the thickness of the electrode and crystal assembly and yet which provides adequate electrical insulation and mechanical resiliency for the 'mounting of a piezo electric crystal element for normal vibration in its course of operation in an electrical circuit.

Other and further objects of my invention reside in the improved construction of a low cost mounting for a piezo electric crystal as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a view illustrating the piezo electric crystal unit assembly or my invention about to be placed in the circuit terminal device or holder; Fig. 2 is a front elevatlonal view of the piezo electric crystal unit assembly of my invention; Fig. 3 is a side elevational view of the piezo electric crystal unit assembly; Fig. 4 is a vertical sectional view through the piezo electric crystal unit assembly taken on line 4-4 of Fig. 2; Fig. 5 is a unit assembly the parts of which are shown in Fig.

7; Fig. 9 is a vertical sectional view of the structure of Fig. 8 taken substantially on line 9-9 of Fig. 8; Fig. 10 is an enlarged vertical sectional 2 view through the piezo electric crystal unit assembly taken substantially on line Ill-ill of Fig. 8, the view being enlarged in order to more clearly illustrate the coaction of the several parts; Fig. 11 is a front elevational view of the piezo electric crystal unit assembly of my invention mounted in the circuit terminal assembly; Fig. 12 is a side elevational view 01' the piezo electric crystal apparatus of my invention with certain parts broken away to more clearly illustrate the manner of detachably mounting the piezo electric crystal unit assembly in the circuit terminal assembly of my invention; Fig. 13 is a, top plan view of the piezo electric crystal apparatus of my invention partially broken away to show the piezo crystal unit assembly detachably'mounted in position in the circuit terminal assembly; Fig. 14 is a side elevational view of the circuit terminal assembly employed forlmounting the piezo electric crystal unit oi. my invention; and Fig. 15 is a top plan viewof the electric circuit terminal assembly illustrated in Fig. 14.

With the allocation of many additional frequencies in the frequency spectrum for various services in which the public interest is paramount, the matter of controlling the frequency of operation of signalling circuits'has assumed enormous proportions. The construction of frequency control apparatus on a mass production scale at low cost is important for the adequate development of the art. The piezo electric crystal unit assembly of my invention has been developed with a view of meeting requirements of the art from the viewpoint of quantity production at low cost. I provide a shell-like container into which a spring device may be inserted as a resilient support for the electrode and piezo electric plate assembly of the piezo electric crystal unit. The piezo electric plate assembly is arranged with respect to the electrodes to permit free vibration thereof. The spring device serves both as a centering means for one of the electrodes as well as to provide a yieldable support for the electrode assembly. A retaining ring of insulation material embraces the other of the electrodes and serves as a centering means therefor within the enclosing shell. The enclosing shell is rolled to a position engaging the retaining ring thereby completing the piezo elec tric unit assembly. An inexpensive and compact form of spring clip holder is provided for detachably mounting the piezo electric crystal unit assembly.

The assembly may be manufactured either in the form of a rectangular shell-like encased unit or as a circular shell-like encased unit. I have 3 found the construction highly practical for inexpensive mass production and as having low electrical capacity and a high degree of electrical efficiency.

Referring to the drawings in detail Figure 1 shows one form of piezo electric crystal unit assembly designated by reference character i about to be inserted or removed from the cuplike support designated at 2 as mounted upon supporting base 3. The piezo electric crystal unit assembly I comprises the shell-like metallic cup 4 in which there is inserted the ring-like spring member 5. The ring-like spring member 5 is sinusoidally shaped about its periphery and has an external diameter which substantially conforms with the internal diameter of the sheetlike cup 4. The ring-like spring member 5 thus serves as a centering means for the circular electrode 6. Electrode 6 has a central projection 'i thereon which has an external diameter conforming with the internal diameter of the ringlike spring member 5 so that the ring-like spring member 5 fits over the projection l of the electrode 6 sufliciently to center the electrode 6 within the shell-like cup I. The electrode 6 is centrally recessed on its opposite face as represented at 8 leaving the peripheral armular land portion 9 which provides a mechanical support and an electrical contact for the corners of the piezo electric plate represented at in.

The opposite electrode of the piezo electric crystal unit assembly is shown at ii as having a recessed central portion i 2 and an annular peripheral portion H. The annular peripheral portion It serves to mechanically and electrically engage the corners of the opposite face of the piezo electric crystal plate in. The opposite side of the electrode ii has central projection i5 thereon which extends into the internal diametrical portion of the retaining ring i6 and serves as an electrical terminal. Retaining ring i6 is formed from insulation material and is provided with a circular recess I! in one side thereof terminating in an annular shoulder i8 which receives and forms a seat for the circular peripheral portion of the circular electrode ii.

, The circular recess I! in retaining ring i6 is of suificient depth and diameter to receive the circular electrodes ii and 8 in loose filling relation and allow vibratory movement thereof. The retaining ring l6 has an external diameter. substantially conforming with the internal diameter of the cup or shell-like metallic casing l for thereby centering electrodes i i and 6 within the casing. Thus electrode 6 is centered by its entry into circular recess il in retaining ring i6 against ring-like spring member 5 while electrode ii is centered wholly within recess i i of retaining ring i6 for thereby assembling the electrodes with respect to the piezo electric plate i0 in stacked arrangement within the shell-like container 4 under the yieldable control of ring-like spring member 5. Electrical connection is completed from electrode 6 to metallic casing 4 through spring 5. The assembly thus described is maintained in position by rolling over the extremity of the skirt of the shell-like casing l as represented at Ill. The rolled over extremity i9 presents a circular edge 20 thereof in contacting relation to the retaining ring i6 of insulation material for maintaining the piezo electric crystal unit in assembled relation. The depth of the shell-like container 4 only slightly exceeds the combined eifective thickness of the assembly constituted by retaining ring I, electrodes 8 and H,

considered in conjunction with the thickness of the piezo electric plate i0 and the effective depth of ring-like spring member 5. Thus the piezo electric crystal unit assembly is free to vibrate in the generation of piezo electric current at maximum efficiency.

In Figs. 1-6 I have explained my invention as directed particularly to a circular construction of piezo electric crystal unit assembly. Certain mass production procedures may be carried out more expeditiously with a rectangular or square construction of piezo electric crystal unit assembly. Figs. 7-10 illustrate my invention as applied to a rectangular or square type of piezo electric crystal unit assembly. In this arrangement the metallic container or shell is pressed from sheet-like material to form a substantially square container represented at 2| which receives the spring-like device 22 of peripheral outline substantially conforming with the internal shape of the sheet-like container 2|, the springlike device being of sinusoidal shape for presenting one bearing surface directly against the end wall of the container 2i and the alternating bearing surface against the periphery of the electrode represented at 2!. The electrode 23 has a peripheral contour corresponding in shape to the internal shape of container 2i with a central projection 24 thereon extending through the interior of the rectangularly shaped strip-like member constituting the spring-like device 22. Electrode 23 is centered within the sheet-like container 2i by its loose fitting entry into the recess 32 in rectangular retaining ring 3i. Electrode 23 is provided with lands at each of the corners thereof shown at 26 projecting from the central portion represented at 25 and providing supports for the corners of the piezo electric plate Ill. The fact that the piezo electric plate is contacted at the corners only by electrode 23 insures free vibration of the crystal throughout its area.

The opposite electrode 21 ha lands 2! at the opposite corners thereof projecting from the central circular portion 28 thereof to establish mechanical and electrical contact with the corners of the opposite face of piezo electric plate ID. A central projection 30 of circular shape extends from the opposite side of electrode 21 as shown. A rectangular or square retaining ring of insulation material shown at ll serves to mount the

electrodes

21 and 23 in position with respect to shell 2| in insulated spaced relation thereto. Retaining ring ll of insulation material has a recess 32 formed therein conforming in contour to the peripheral shape of

electrodes

21 and 23 whereby electrode 21 may be seated against shoulder 23 of retaining rin 3i with the central portion 30 thereof partially projecting through the circular aperture 34 in the opposite face of retaining ring 3|. The dimensions of retaining ring ii are such that retaining ring 2i substantially conforms to the interior cross section of container 2i thereby centering

electrodes

21 and 23 within the unit assembly and in coaction with spring member 22 centering the unit assembly with respect to the interior walls of the container 2i. The

length of the skirt or wall of container 2| is' such that the peripheral extremity of the skirt or wall 2| may be rolled over as represented at 35 for retaining the piezoelectric crystal unit assembly in position within the shell-like container 2!. The depth of the container 2i is such that when the peripheral extremity is rolled over as represented at 35 the combined thickness of retaining ring 3|, electrodes 2'! and 28 and piezo electric crystal, III in association with spring member 22 allows free vibration of the piezo electric crystal within the container.

The circuit term nal assembly for mounting the piezo crystal unit assembly I comprises cup-like support 2 in the form of a bracket having a central portion 38 mounted upon supporting base 3 and a pair of

side portions

31 and 38 which are shaped to conform with the contour of the piezo electric crystal unit assembly I. a The side portions 3! and 38 have inwardly directed planelike portions 31a and 38a which serve as abutments against which the piezo electric crystal unit assembly I may be centered and maintained as shown. The portion 36 of the bracket serves as a mounting means for the block 39 of insulation material which is secured thereto in any suitable manner such as by means of screws 38a and 36b. The upper portion of the block 39 of insulation material is grooved at "a and into this groove the resilient strip-like member III is secured by means of screw 40a. Resilient striplike member 40 has a contacting portion 40b directed inwardly through the open end of the button or disc-like piezo crystal unit assembly for establishing connection with the projecting face l5 of the electrode ll. Strip-like member 40 tends to continuously urge the piezo electric crystal unit into supporting relation with the

abutment portions

31 and 38 01' the cup-like support 2. The resiliency of the strlp-like member 40 is such that the button or disc-like piezo crystal unitv assembly may be readily inserted or removed from the support for facilitating the change of the associated electrical circuit from one frequency to another. The electric circuit connections are made to the terminal assembly through conductors, one of which I have indicated at H connected to one of the securing screws 36c and the other of which I have shown connected at 42 as connected to a lug 40c struck from the resilient strip-like member 40. The mannerof supporting the square or rectangular shape or piezo electric crystal unit of Figs. 7-10 is the same as the method of mounting the circular piezo electric unit assembly of Figs. 1-6 except that the cup-like support 2 has the abutment portions thereof differently shaped to conform with the shape of the container constituting the iezo crystal unit assembly.

I have found the embodiments of my invention herein highly practical in construction for mass production at low cost, but I realize that modifications in detail may be made and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. A piezo electric crystal unit assembly comprising a metallic shell-like container, a spring member mounted in said container, an electrode supported by said spring member. a piezo electric crystal plate establishing surface contact with member.

2. A piezo electric crystal unit assembly comprising a metallic shell-like container, a strip-like yieldable member substantially conforming in shape with the interior contour or said shell-like container, an electrode supported by said strip like yieldable member, a piezo electric crystal plate having one of its surfaces establish surface connection with said electrode, a second electrode establishing connection with the other surface of said piezo electric crystal plate, a, retaining ring of insulation material engaging said last mentioned electrode and a confining connection between the peripheral edge of said shell-like container and said retaining ring.

3. A piezo electric crystal unit assembly comprising a shell-like metallic container, a relatively flat strip-like spring member disposed against the end wall of said shell-like container, an electrode supported by said strip-like spring member,

electrode within said shell-like container and a binding connection between said retaining ring and the peripheral edge of said shell-like container.

4-. A piezoelectric crystal unit assembly comprising a pair of parallel extending electrodes each being recessed centrally of the face thereof providing peripheral lands thereon, a piezo electric crystal plate mounted between the lands of said electrodes and free to vibrate in the recesses provided in said electrodes, a shell-like metallic casing, means for yieldably supporting one of said electrodes with respect to the interior end wall of said shell-like metallic casing, a retaining ring of insulation material peripherally embracing the other of said electrodes and a peripheral connection between said retaining ring and the opposite end or said shell-like container.

5. A piezo electric crystal unit assembly comprising a pair of parallel extending electrodes each being recessed centrally of the face thereof providing peripheral lands thereon, a piezo electric crytsal plate mounted between the lands of said electrodes and free to vibrate in the recesses provided in said electrodes, a shell-like metallic casing, a strip-like spring member disposed in substantially co-planar relation to the interior I- end wall of said container and one of said electrodes, said strip-dike spring member being sinusoidally shaped with the opposite alternate faces contacting the internal end wall of said shell-like container and said first mentioned electrode for resiliently spacing said electrode from the interior end wall of said container, a retaining ring of insulation material peripherally embracing the other of said electrodes and a Deripheral connection between said retaining ring and the opposite end of said shell-like container.

6. A piezo electric crystal apparatus comprising in combination a bracket member having a pair of arms with laterally disposed abutments thereon, a disc-like piezo crystal unit assembly engageable by said arms, said assembly including a metallic shell-like container closed at one end and open at the other end, an electrode member supported in insulated relation thereto and accessible through the open end of said shell-like container, said arms being shaped to conform with the contour or said disc-like piezo crystal unit assembly and establish electrical connection with the shell thereof and engaging the same and a resilient arm supported in insulated relation to said bracket member and establishing both electrical and mechanical connection with one or the electrodes of said piezo electric crystal unit assembly.

7. A piezo electric crystal apparatus, comprisingin combination a bracketmember having a pair of arms with laterally disposed abutments thereon, a piezo electric crystal unit assembly included within a metallic shell-like container closed at one end and open at the other end, electrode members and a piezo electric plate arranged within said container, one of said electrode members being supported in insulated relation to said shell-like container and accessible through the open end of said shell-like container, said arms being shaped to conform with the contour of said piezo electric crystal unit assembly and engaging the same, and a third arm insulatingly mounted with respect to said pair of arms and projectible through the open end or said metallic shell-like container for establishing mechanical and electrical connection with the electrode accessible through the open end of said metallic shell-like container and maintaining said piezo electric crystal unit assembly in detachable engagement with the laterally disposed abutments on said pair of arms.

8. A piezo electric crystal apparatus, comprising in combination a bracket member having a pair of arms with laterally disposed abutments thereon, a third arm insulatingly supported with respect to said bracket member intermediate said pair of arms and resiliently tensioned in the direction of said pair of arms, a piezo electric crystal unit assembly including a metallic shelllike container closed at one end and open at the other end, a piezo electric plate and electrode assembly disposed within said container, one of the electrodes 0! the electrode assembly being insulatingly supported with respect to said container and accessible through the open end 01 said container, said piezo electric crystal unit assembly being detachably engaged against the laterally disposed abutments oi said pair of arms with said third arm projecting through the open end of said container and establishing detachable electrical and mechanical connection with the electrode accessible through the open end of said container.

- 9. A piezo electric crystal apparatus, compris ing in combination a supporting member having a pair oi. arms with laterally disposed abutments thereon extending in a common plane, a third arm insulatingly mounted on said supporting member intermediate said pair of arms and terminating in a contact device, said third arm being tensioned ior normally urging said contact device toward the plane of the laterally disposed abutments on said pair of arms and a piezo electric crystal unit assembly comprising a metallic shell-like container closed at one end and open at the other end, a pair of electrodes, a piezo electric plate disposed between said electrodes, one of said electrodes being resiliently supported with respect to the closed end of said metallic shell-like container and the other of said electrodes being accessible through the open end of said shell-like container, said piezo electric crystal unit assembly being detachably engaged against the laterally disposed abutments of said pair of arms when the contact device on said third arm is resiliently engageable against the other electrode through the open end of said metallic shell-like container.

GEORGE s. WACHTMAN.