US2574136A - Vibratory frequency standard apparatus - Google Patents

Description

VIBRATORY FREQUENCY STANDARD APPARATUS Filed Nov. 29, 1947 Patented Nov. 6, 1951 UNITED STATES PATENT OFFICE VIBRATORY FREQUENCY STANDARD APPARATUS 11 Claims. 1

My present invention relates to time measuring instruments including particularly vibratory frequency standard devices and apparatus. Examples of such devices and apparatus appear in my prior Patents 2,260,847 and 2,260,848 of October 28, 1941 issued to Warren Telechron Company, the instant invention being by way of improvement upon the substance of said patents.

Among the objects of the invention are to avoid objectionable torsional vibration effects in the vibratory element, to increase the voltage output from the vibratory unit with resultant decrease in external disturbance effects and reduction in amplification requirements, and to obviate separate driving means and plural circuits for the vibratory element. These and other advantages including novel provision for adequate temperature compensation will be evident from the following description in connection with the accompanying drawings, wherein:

Fig. 1 represents in front elevation one form of vibratory device embodying the invention;

Fig. 2 is an enlarged sectional view as if on the line 2-2 of Fig. i;

Fig. 3 is a detail sectional view, also on a scale larger than Fig. 1, showing one of the anchorage arrangements as for example at the upper left in Fig. l; and

Fig. 4 illustrates an electrical driving and con trol circuit comprised in the apparatus and especially adapted for use with the device of Figs. 1 to 3.

The invention-will best be understood from a consideration first of the mechanical, electromagnetic and electronic means of the illustrative embodiment in the accompanying drawings. Referring now to Figs. 1 to 3, the apparatus or vibratory unit in some instances have rigid support but preferably and as shown a mass H on which all other mechanical parts are mounted is resiliently suspended from a suitable support (not shown) as by a spring l2. A double cantilever, bridge or bar 14 is centrally secured to the supporting mass H as by bolting or othertail in Fig. 3. The adjacent end of the wire it is secured in a metallic anchor l8 insulated from the bridge it as by a non-conductive grommet or the like I8, the wire [6 being fastened to the anchor [8 as by hard soldering as at l8. One external lead wire 33 is connected in electrical communication with the wire I6 as by soft soldering to the anchor H! as at 33. The second vibratory wire ll of the pair similarly has the upper end connected to the other end of the bridge M. by a corresponding anchor IS with insulating grommet IS, the other external lead 34 being attached to the anchor l9 similarly as in Fig. 3.

At the lower ends the vibratory wires I6, I! are attached to the respective ends of the lower bridge 22 by means of fastenings 20, 2| which may be similar to those for the upper ends of the wires except that no lead connections are here needed.

At an intermediate portion of their lengths the two vibratory wires [5 and I1 support a coil designated generally at 15 which under this invention takes part in the pluralfunctions of actuator and of controller in lieu of a plurality of separate elements therefor as in my prior patents noted. This coil [5 positioned upon the wires l6, H by extending the latter fixedly through corresponding metal bushings 29, 29' set in the spool or core [5 of the coil at diametrally spaced locations thereon. The coil 15 and bushing 29 for the wire [6 are seen on a larger scale in Fig. 2. The ends 30 of the coil winding I5" are respectively secured to the metal bushings 29, 29 and hence electrically to the wires [6, 11, one coil end 30 and the solder connection 3| to the bushing 29 being seen in Fig. 2.

The two wires l6, H are kept in tension by a weight 23, Fig. 1, suspended thereon through the medium of the lower cantilever 22. The attachment of the weight 23 as shown is by means of upper and lower blocks or jaws 24, 25 at oppcsite faces of the bridge piece 22 and having opposed gripping projections 24a, 25a. The blocks are clamped to the bridge 22 and secured to the weight 23'as by a through bolt 26. Ac cordingly an accurate distance is maintained between the points of clamping of the bridge 22 and the points of attachment 20, 2| of the wires I6, ll thereto.

In association with the wire-supported coil 15 there is provided, noting particularly Fig. 2, a

strong permanent magnet 21 having opposite poles N and S. This magnet is mounted on the mass H as by a pendant bracket 28 to which nating; fields whether. magnetic or electrical. accordance with the invention as herein disclosed the magnet is secured as by a screw bolt 32. The permanent magnet 21 is thus so disposed that the poles thereof are presented one above and one below the adjacent or rear portion of the coil l5, a portion thereof which is offset perpendicularly from the plane of the twin wire and bridge system. That is, the arrangement is such that a portion of coill5 which projects generally perpendicularlyto themain plane of thesystem is placed directly in the'field of the magnet 27. By this provision of a relatively fixed permanent magnet in operative association with a coil on and movable with the vibratory'element a powerful magnetic field is made available.

Referring again to Fig. l, the distance between the bushings 29, 29 of the coil l5at which'th'e' vibrator wires l6 and IT- support. the coil is deliberately made different to, herein considerably less than, the lengths of the individual bridges l4 and 22 between the respective points of wire. connection I8; [9 and 20, 2| thereat. Accordingly the twin vibrating wires I6 and H are each. given anangular and herein opposite reentrant formation together approximating the shapeof a.-. letter X. In this angular formation the" wires [6,. I are" disposed a single plane, presenting a. stiff." uniL-planar structure resisting forces. acting: in the common. plane. thereof. Hence: periodic vibration inany direction within the common plane: of: the wires is practically impossible. Yet this same angular or X-form structure is; free. to. vibrate periodically in av direction perpendicular to the plane containing the wires [6, I! while at the same time effects of torsionalvibrationwhich. have sometimes proved troublesome in. previous: constructions are. substantially eliminated: For similar reasons the: described vibratory structure: of,the invention, involving separate wires l6, l1 electrically insulated. from each other;, makes it'ieasible; to mount a vibrating coil such.- as; l-5 on the; wires themselves. By then associatingwith the coil a relatively stationary strong' permanentf magnet such as 21' a comparatively-high electromotive' force may be hadirr and. from the moving coil. The. resultant current is; carried by the vibrating wires l6,..-|-1- themselves: and: viathe leads 33; '34'to' a stationary circuit to-be: described.-

In: earlier' devices and apparatus of this type a. vibratingcoil. would be; impracticable both because-of the. torsional vibratory efiects referred toandbecause-onlya singleconductor was available-ior current-carrying purposes and them.- troductionor a second conductor'would objectionably interfere? with the: vibratory action. Hence prior efiorts along; this: general line, as forexample. inmy patents.- identified, were limited to mounting; ama-gnet. (permanent) on the-vibratory element, such magnet necessarily being smallandproducing. a relatively weak field. In consequence the-output: voltage in earlier instruments was comparatively low as contrasted with that obtainable under-thepresent invention and accordingly was more. subject to objectionable influence by external electrical disturbances either. of-a static. nature or arising from alterthe available voltage generated by the vibratory twin. wire element [-6 Ila-isseveral times. greater than heretofore had. Consequently less. amplification is. required and the "associated electric system. may. be. simplified, making for materially battered amplitude control. 1

Still considering particularly Fig. 1', the geometrical form of the vibratory system, including the symmetrical angular or X-arrangement of the twin wires I6, I? provided by the spreader bridges I4, 22 and the intermediate spanner or tie means offered by the body of the coil 15 (or separately therefrom if preferred) affords automatic temperature compensation. It will be apparent that the bridges i4 and 22 constitute elastic couplings between the corresponding ends of the vibratory wires, as do also the wires between the weighted and the fixedly supported bridges. The materials of these wires ES, IT and ofthebridges I4, 22 are selected to have different temperature coeflicients. For example, the selection may be. such that a tendency of the wires l6; ll'toelongate and become less elastic and hence. of decreased rate of vibration with rise in temperature may be fully ofiset by a simultaneous increase'in length of the bridges I4, 22. In the course of such thermal length changes the angles at the X-formation are altered in such way as to increase theatensionin the wires with increasing temperature. with resultant efiect of. increasing the: rate of vibration. The. reverse applies in case of temperature decrease. In any instance, by proper calculation of the angles at the X or other angular. formation of. the system any increase in vibratory rate fromthe relatively different expansionoff the wires. and the attachments therefor maybe made to compensate closely for any change in the vibratory rate produceddireetly in the wires themselves by temperature change, the converse being true. for; vibrational rate variations under: temperature change in, the. opposite sense.v

The apparatus as a whole further comprises an electrical and electronic-circuit so associated with thevibratory device or system such as that ofFig. 1 that vibration therein is maintained at a constant amplitude.

As diagrammatically represented in Fig. 4 such circuitmeans comprises triode elements A and B, which; maybe disposed in a common twin tube. The respective filaments or cathodes 53, 5d of the triodes A and B are interconnected and are biased by; a. slider 16 operable along a voltage divider 14,45 connected with a direct-current voltage source regulatable by a tubeorother voltage regulator H. The plates 55 and 560i therespective'triodes A and, B are. supplied from the same or other Dz C.source through plate resistors S-Tand t8 and. are connected directly to ground, one through a high resistance pair H and I3 and the other through a similarresistance means 10 and 12..

At-intermediate points designated. at 6,2: and63 ontherespecti-ve resistance elements it, 12 and H, 13, the: grids: 5| and 52 of" the triodes A and B are individually connected. The conjoint drivingand' control coil 15 of the vibratory system is connectedacrossthe same points 62' and 63 as indicated by the lead wires 33 and 34 respectively. Thus the two grids are cross connected each to the plate of the opposite triode so as to form a circuit which tends to oscillate. It will be noted that no condensers are present in this circuit, wherefore current and voltage impulses are substantially in phase.

The connection points 62 and 63 mentioned are so located that the D. C. voltage tothe grids is about equal, and by regulation of the slider 16 theD. C. voltage to the cathodes is made approximately the same.

From the foregoing in connection with the drawings it will be evident that the slightest voltage set up in coil l by each minute vibration of the twin-Wire vibrator element I6, I! will be considerably amplified at plates 55 and 56, and that positive feed-back current will appear in the resistances H and tending to increase the amplitude of vibration of the wire element I 6, ll. This build-up process continues until the generated voltages at the grids approach the points of cut-off of the respective triodes, whereupon constant amplitude of vibration will be maintained. This amplitude can readily be controlled by the position of the slider 16. If desired further amplification of voltage may be had, as by feeding that here available to the grids of other tubes by suitable coupling with the plates 55 and 56.

Thus in further contrast to the prior apparatus as typified by the herein identified patents the improved vibratory time standard of the present invention avoids the use of plural circuits at the vibrating device or system and dispenses with the necessity for plural separate driving and control elements thereat. As herein disclosed the signals created by the vibrating twin-wire element are directly amplified in a push-pull circuit arranged to provide feed-back directly and in exactly the same phase to the generating coil 15. Therefore in effect the one coil serves the plural functions of motor or driving agent and of controller, setting up and maintaining its own vibration at a constant value.

The two wires l5, i! which with the movable coil l5 constitute the vibrating element them selves furnish all needed connections to the external electrical system. As herein disclosed there is no auxiliary or secondary drive circuit coupled either magnetically or mechanically to a primary or pick-up circuit. Further, in the single conjoint electric driving and control circuit of the invention any phase variations between the output of the vibrating coil and the operation-maintaining feed-back are made exceedingly small by reason of maximum elimination of capacity and inductance effects and through the use of relatively high-resistance connections. The balanced push-pull circuit such as disclosed tends to cancel out the effects of outside electrical or magnetic disturbances upon the system, it being noted that in accordance with the invention there is provided straight resistance amplification of the signal from the vibrating coil with a small amount of in-phase feed-back for maintaining the vibration.

My invention is not limited to the particular embodiment thereof illustrated and described herein, and I set forth its scope in my following claims.

I claim:

1. For frequency standard apparatus, a, vibratory system comprising a pair of laterally spaced equal length wires, supporting and tensioning bridges to which the opposite ends of the wires are insulatively connected, means centrally securing one bridge to a support, a tensioning weight attached to the other bridge, means angularly deflecting the wire symmetrically in a common plane so that the wires, bridges and said means define a uniplanar system relatively stifi and resistant to vibration in the plane thereof but adapted to vibrate periodically transversely to that plane, a coil medially carried by the wires for unidirectional vibration therewith, and a relatively stationary permanent magnet positioned to have its field traversed by the vibrating coil.

2. For frequency standard apparatus, a vibratory system comprising two separate elongated electrically conductive vibrating elements, spreader bridges at the opposite ends of the elements for holding them in spaced and mutually insulated relation, means nonconductively spanning the elements at an intermediate point along them and according them a symmetrical uni-planar form including angularly related portions for each element, fixed supporting means for one bridge, an equipoised tensioning weight attached to the lower bridge, the tensioned elements and bridges disposed in a common plane and being resistant to vibration in that plane but free to vibrate periodically in a direction transverse thereto, a coil intermediately mounted on and electrically connected across the elements so as to take part in the vibration thereof, a fixed strong permanent magnet disposed with its field across a projecting portion of the coil whereby a substantial voltage is set up in the coil attendant on the vibration, and an external electrical connection for each of said tensioned elements.

3. A time measuring instrument comprising generator means including a fixed magnet and a coil movable across the field thereof; means for vibrating said coil at a constant rate including a pair of wires tensioned between opposed cantilever elements and convergently embraced intermediate their ends by said coil whereby the uniplanar wires have a general X-formation, the coefficients of expansion of the cantilevers and wires being such that for a given temperature change the change in elasticity of the wires is compensated by a tension change; and a balanced push pull oscillator connected through said wires to said coil and controlled by said generator and maintaining a constant amplitude of vibration for said coil.

4. The structure of claim 3, wherein the wires become less elastic with increase in temperature and wherein the cantilever elements have a coefficient of expansion predeterminedly in excess of that of the Wires and such that for a given temperature rise the change in the angles of the X and corresponding increase in the tension of the wires compensates for the decrease in elasticity of the wires.

5. For frequency standard apparatus, a vibratory system according to claim 1 wherein the coefiicient of elasticity of the wires and the coefficients of expansion of the Wires and bridges are predeterminedly such that for a given temperature change the change in the length and elasticity of the wires is compensated by a change in tension of the wires, and the rate of vibration of the coil is maintained substantially constant.

6. Frequency standard apparatus comprising a vibratory system including a pair of laterally spaced wires, supporting and tensioning bridges at the opposite ends of the wires, a support for one bridge, the other bridge having a tensioning weight applied thereto, and means angularly deflecting the wires symmetrically in a common plane intermediate the ends thereof whereby the wires and bridges define a relatively stiff, uniplanar system which is substantially non-vibra-- tory in the plane thereof; and a coil element and a permanent magnet in voltage creating relation under relative movement thereof, one element mounted on the wires for vibration therewith and the other element having adjacent relatively stationary support.

'7. Frequency standard apparatus comprising a support, a vibratory system suspended thereon including a pair of laterally spaced vertical wires, upper and lower supporting and .tensioning bridges at the opposite ends of the wires, the

lower bridge having a tensioning weight thereon, and means convergently tying the wires intermediate the ends thereof whereby the wires, tie means and bridges define a relatively stiff uniplanar system of general X-form limiting vibration to the direction normal .to the plane thereof, a permanent magnet element and a coil having a portion thereof in-theiield of the magnet, one of said elements mounted on and so as to vibrate with the wires and the other element having'relat'ively fixed carriage on said support.

' '8. In frequency standardapparatus, a vibratory system comprising a support means, a first elastic bridge connected thereto, a second elastic bridgespaced therefrom, a pair of wires connecting said bridges, a gravity weight associated with said second bridge for maintaining said wires under uniform tension, and meansengaging and defiecting intermediate portions of said wires uniplanarly into a symmetrical angular geometric Iiorm whereby the system is given a fixed reference planefor vibration transverse thereto, the

necting said bridges, a gravity weight associated with said second bridge for maintaining said wires under uniform tension, and means uniplanarly deflecting the wires into a symmetrical geometrical form whereby the system has vibratory capacity only transversely to a fixedreierence piane, the coefficient of expansion of the bridgesbeing predeterminedly difierent from that of the wires, such that for a given temperature change the resultant changes in lengths and in wire tension have a compensating efiect on the vibration rate of the wires to maintain it substantially uniform.

10. A time measuring instrument comprising generator means including a fixed magnet and a coil movable across the field thereof, means for vibrating said coil at a constant rate including opposed cantilever elements, a tensioning weight supported by one cantilever element, and a. pair of wires tensioned between said cantilever elements and convergently embraced intermediate their ends by said coil whereby the uniplanar wires have a generalX-iormation, the coefiicient of expansion of the cantilevers and \vire being such that for a given temperature change the change in the length and elasticity of the wires is compensated by a change in the forcecomponent of said weight expressed along said wires resultant from a change. in the angles of. said X-formation, and a balanced push-pull oscillator connected through said wires-t said coil for the purpose of maintaining a constant amplitude .of vibration of said coil.

11. Thestructure of claim 10, wherein'thewires become longer with increase in temperature and wherein the cantilever elements have a coefiicient of expansion predeterminedly in excess of that of the wires such that for a given temperature rise the change in the angles of the X-formation and corresponding increase in the tension of the wires compensates for the increase in length of the wires.

HENRY E. \VARREN.

nnrnnr nons CITED I 'ifhe following references areof record 'in the file of this patent:

UNITED STATES PATENTS Number Name Datei,602,824 Jones Oct. 12, 1926 1,748,858 Barton Feb. .25, ,1930 1,852,594 Show Apr. 5, 1932 2,252,846 Gianninni et al. Aug. 19, 1941 2,260,847 Warren Oct. 28, 1941 2,260,848 Warren Oct. 28, 1941 2,265,911 Siegel Dec. 2 1941 2,302,895 Root Nov. 24, 1942 2,412,536 Ri'eber Dec. 10, 1946 2,415,022 Morrison .d Jan. 28 1947 2,427,920 Morrison Sept. 23, 1947 2,440,439 Gilman .Apr. 27, 1948

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