US2246296A - Oscillation translating system - Google Patents

Description

June 17, 1941'. MaJ, DITORO y v 2,246,296 OSCILLATION THAN{SL'I'NG SYSTEM f I Fuga Deo. 28, 1959 2 sheets-sheet 2 (ttorneg Patented June 17, 1941 OSCILLATION TRANSLATING SYSTEM l Michael J. Di Toro, East Orange, N. J., assignor to Thomas A. Edison, Incorporated, West Orange, N. J .v, a corporation of New Jersey l Application December 28, 1939, Serial No. 311,325

" 1s claims. (ci. 274-1) This invention relates to oscillation translat ing systems and more particularly toimproved means for suppressing or mitigating undesired i mechanical oscillations (i. e., vibrations) in such systems.

The invention has especial utility in combination with phonographic apparatus such, for

example, asiphonographic translating devices of the recorder type which convert acoustical or electrical oscillations into corresponding mechanical oscillations, and is herein described,

stylus and the moving record is like that of a Y compression springi. e., in the nature of a compliance-dn that an increased penetration,

or displacement, of the stylus into the record material -is resisted by an increased restoring force. (It will be understood that the term "commean the deflection of a spring structure per unit applied force;v however, inasmuch as, there is no ordinary spring involved and the action of the recorder on a moving record is the equivalent pliance is herein employed in its usual sense to y of that fa spring; the character of this action' will be hereinafter referred to as the effective compliance between the recorder and the record.) Such action is conducive to obtaining a constant depth of groove; in fact,lby reason of this action the groove depth iscommonly controlled by permitting a biasing of the recorder against the record to be taken up entirely by the force exerted upon the stylus by the moving record-'- i. e., by permitting the recorder to float by way of its stylus upon the surface of the moving record. When the groove depth is controlled in this manner there is, however, a strong tendency for a compliance usually principally made Vup of the effective compliance between the recorder andv the record andotherwise of the compliance characterizing the recorder, to resonate with certain masses of the recorder (whicli masses may herein-be referred to as the effective mass of the Hrecorder) Such tendency, towards recorder resonance renders Atheaction of @he recorder in- Astable. As a result, in the case of a vertical or hill-and-dale recording, the recorder becomes highly sensitive to input oscillations atfrequencies approaching the resonant frequency of the recorder, thereby rendering the frequency-response characteristic of the recorder non-linear; and in accentuated cases, the recorder is at tim'es placed in sustained vibration in response to recurring shocks or external vibrations to .cause a continuous modulation of the groove depth-which modulation results in the recordation of a constant note in a-hill-and-dale type of recording and in tracking and other difficulties during the reproduction of aI lateral type of recording. To suppress or mitigate these effects there has been employed a damped vibration absorber such as is described in my Patent No. 2,177,692, issued October 31, 1939, and entitled Oscilla'tion translating devices.

A damped vibration' absorber as here men- 4 tioned is a particularly effective means for sup pressing undesired vibrations in mechanical systems. A criterion for maximum effectiveness of the damped vibration absorber is, however, that it be tuned to a frequency bearing Aa definite relationship to the frequency of vibration to be damped or suppressed. 'I'his relationship is such that the absorber is tuned to a frequency slightly or appreciably belcwthat of the vibration to be suppressed dependingupon whether the effective (or damper) mass of the vibration absorber is small or large relative to the effective mass of the system to which the absorber is applied. Thus in the application of the vibration absorber to a phonographic recorder, the absorber will be effective to suppress a resonance effect between the recorder and the record only so long as there exists proper relative tuning between the absorber and the recorder.

It has been found that the resonant frequency of instability of a phonographic recorder does not remain constant but that it varies widely with temperature.l This variation is caused by the effect of temperature on the eiective compliance between the recorder and the record.

vThis compliance may be considered equal to the product oi'v a constant, depending principally upon peripheral record speed and shape of the recorder stylus, by'a temperature-variable factor which depends for example upon such characteristics ofthe record material as its viscosity and stimness.

employed in connection with dictatihg. machines. the viscosity and stillness of tl'ie record "material vary so as to cause 'an increasing elective compliance betvnrcen-tiie.v the' recorder l For record 4materiais'of wax-likey character,.-snch as is commonly used in records ture.

` more fully appear from with increasing temperature, and a decreasing effective compliance with decreasing temperavaries to cause the frequency of the recorder resonance to vary several timies throughout an operating temperature range from 50 F. to

`90 F., thevariation being such that the recorder resonant frequency decreases with increasing temperature, and vice versa. In view ofthis variation, a damped vibration absorber whose natural (i. e., 4resonant) frequency either does not vary with temperature, or varies in widely dierent degree from that in which the resonant frequency of the recorder varies, will be incapable of suppressing the recorder resonance effects except within a limited ambient temperature range.

It is an object oi my invention to provide means capable of suppressing or mitigating frequency-varying resonance eiiects' in mechanical systems in highly eilicient manner.

It is another object to eiectivelysuppress, in mechanical systems, undesired vibrations which vary in frequency with temperature.

In typical cases this eii'ective compliance Figure 12 is an enlarged view in perspective. of a portion of my invention as applied to the recorders of the prior ngures.-

My invention is illustrated herein, in Figures 1 through 6, in connection with an acoustical type of phonographic recorder (i. e., a recorder for directly converting acoustical oscillatloi'm .into corresponding mechanical oscillation of a recorderl stylus) and, in Figures 7 through 11, infconnection with an electrical type ot phonographic recorder (i. e., a recorderffor converting It is another object to provide a temperature- It is a further obiect of my invention to providev an improved phonograph4 system, and an improved phonographic recorder, wherein unde- .sired vibrations are eiectively mitigated or suppressed throughout wide temperature ranges.

It is a still further object of my invention to provide new and improvedmeansand methods by which available damping materials may be employed to effectively suppress resonance effects having predetermined .variations in frequency with temperature change.

Other and allied objects of my invention will the following description and the appended claims. i

`In the description ot my invention reference is had to the accompanying drawings, of which:

Figure 1 is'a partly elevational and partly vertical cross-sectional view lrof an acoustical recorder in which my `invention is incorporated;

Figure 2 is a-substonuauy .horizontal oroossectional view taken substantially along the line 2 2 of Figure 1;

. v vFigure 3 isa cross-sectional view taken sub.

stantially along the line 3--3 oi Figure l; l Figure 4 is -an enlarged sectional view taken along the-line l-fl of Figure 2;

Figure 5 is another 'sectional view. taken substantially along the line L of Figure 4;

Figure 6 is a plan viewgwith parts in section,4

showing one particular form of my invention, as applied to the acoustical recorder of Figures 1 and 2;

Figure 7 is an elevational view oian electricalv recorder in which my invention is incorporated; Figure 8 is a plan viewl of the recorder o! Figure 'lwith a portion 4broken away, the support for the recorder'b'eing shown in cross section: Figure 9 isy a fractional view principally in l section along the line 9- 9 of vFigure 8:

"Figure 10.` is a vertical cross-sectional view l substantially along' theline III- I0 of Figf-ure'l;v l o 'l verticalfsectional view taken lsul)s'tantially'lfillng the line il-I i oi' Figure 10;

Y recording, therecord R is rotated and the carriage 2 is concomitantly fed along the record as by a driving means not herein necessary to show. I

'I'he recorder I may comprisea frame 4 in the form of an inverted cup, which is provided with a central upwardly extending neck 5 and a front downwardly extending lug i. Positioned below the frame 4 is a circular casing 1 which is pivoted to the lug l on a pin 8 for movement towards and away from the record. The bottom of the casing I is closed by a diaphragm 9 which carriesla. mounting 8' i'or a recorder stylus I0. This diaphragm and stylus are adapted to vibrate in accordance with input acoustical oscillations. Such oscillations are transmitted' into the casing 1 by way of the neck 5 and a tube Il which connects the neck to the casing, the tube being provided with upper and lower outwardly flanged portions Il' and Il" of which the upper portion Il slidably ilts the neck I and the lower portion "il" `ilts an apertured dome 'l'` on the casing, the lower portion being retained to the casing to form aV universal joint therewith by a means not herein necessary to show. In this arrangement the casing 'I is free to move up and down relative to the record while yet being maintained lin sound communication with the neck 5. A movement oi' the casing free of the record to place the recorder into inoperative condition may be effected, as desired, by means of `an arm 12, partiallyv shown, which may be moved into contact with a tab Il on the casin to lift the recorder irom the record:

- It will beseen that in this structure the stylus Il is biased against the record bythe weight of the casing ,l and that this biasing force is counterbalancedby the force exerted upon the stylus by the record. During a recording operation, as when `the record R. is rotated and the carriage 2 is fed along the'record, the styluswill form aprogressive spiral `groove in the record. This groove will be ofa generally constant mean' depth predetermined by the record and tool characterlstics and by the biasing abo'v'e mentioned; vibrations oithe stylus Il relative to the casing A asfbecause o! acoustical oscillations beiigtrans mitted into the casing 1 will, however, cause the groove depth tube modulated in the case of recorder stylus I0 to vibrate in response the casing 1 will be largely prevented from movedepth, a portion of the weight ofthe casing may be relieved from the record by -a counter-y balancing structure I4. 'I'his structure is pivoted as at I5 to the underside of the frame I and is connected by a link i6 to the casing, the link 5 being' pivcted at |1 tothe structure il and at i8 to the casing. r

While acoustical oscillations conducted into the casing 1 will cause the diaphragm i and thereto l0 onance of the system. Indeed,.in the present instance the influence on the casing 1 of the vibra- 25 tion of the recorder stylus at frequencies approximating the resonant frequency of the casing with the record may cause extremelylarge amplitudes of oscillation of the casing, which oscil-j lations will cause similarly large amplitudes of oscillation of the recorder stylus lli. 'I'hus frequencies of acoustical oscillations to be recorded which approximate the resonant frequency of the l recorder will be translated into unduly large amresonant frequency.

plitudes of oscillation of the recorder'stylus to 35 cause the recorder to havel a non-linear frequency response characteristic; and in accentuated cases, small yet unavoidable vibrations accompanying the operation of the phonographv may excite the recorder sufficiently-to cause a sustained vibration of the casing 1 relativeto the l surface of -the moving record at the recorder The damped vibration absorber of my aforementioned patent has proven itself an effective means for suppressing resonance effects in phonographic recorders, as a ve'mentioed, provvided there-is no substantial variation in the conditions under which the phonograph is op'- erated. It is found, however,` as aforementioned, 50 that because of the .variation in characteristics oflthe record material withtemperature the effective compliance between the recorder and th record-increases and the resonant frequency lof the recorder decreases with increasing temperature. Phonographsare normally operated 'with-- in a limited temperature rangeof from F. to F.; yet frequently, as in the case of phono- -graphs of the commercial or dictatingmachine variety, they are operated at temperatures below 60 and beyond this limited temperature range, fo'r example, as from 50 F.,to more than 90 F.

-Within such a wide temperature'range the revfectiv'eness ofa damped vlbr.

, tuning of 'the' absorber relativeto the frequency corder resonant frequency may varyby as much as two and one-half times-a variation'in fre- 65 quency far too great to permit effective suppres,

sionbeby means of the' usual damped vibration absor r r.

In accordance with the principle that the ef. tion absorber is 70.

preservedv so long as there is lPreserved a proper of the resonance effects to be suppressed, I have found that .there mayoccur variations both in the absolute frequency of of the absorber 'Iii `of the recorder.

and in the frequency of theresonance effects to be suppressed, without loss in the effectiveness of the absorber, provided the variation in one approximates that of the other. 4Inthe instant invention I utilize this principle to` effectively suppress the frequency-varying resonance effects in a recorder throughout a wide range of temperatures.- Thisis done by causing the frequency of tuning of the damped vibration abf sorber to vary with temperature in substantially the same manner as that in which the resonant `frequency of the recorder varies.

The damped vibration absorber comprises an anti-resonant structure which may be in various forms but which-is preferably-in the form of a resilient, cantilever-mounted beam structure I!v` as shown for example in Figures 5 and 12. The 'beam structure I9 comprisesy a fiat spring 20 -liaving spaced channelled portions, a channelled inner or base portion 20a and a channelled outeror free-end portion Zlib. Between and overlapvping the channelled portions 20a and 20h there is applied a slab 2l of 'a damping material characterized by a high internal resistance as is hereinafter more fully explained; this slab is retained to the spring 20, as by suitable glue or by vul;

canizing, and is secured at its end `portions by means of ears 22 bent over from the channelled portions 20a and 20h into contact with the slab: The reason for a spring configuration having spaced channelled portions is that the length of the unchannelled or flat-portion denitely establishes the effective length of bending of the beam structure and that the stillness of this unchannelledportion will not be critical to clamping conditions at theA channell'ed'end portions of the structure. y

At the free-end portion 20h of the spring 20 there isV provided a localized weight 23' (see Figure 5) which is secured to the spring 2li-by a screw 2l, the screw passing through a slot 25 in the spring which extends longitudinally of the spring to permit an adjustment in the position of the weight relative to the spring, as for purposes of tuning thev beam structure to a predetermined frequency. For the purpose :of keeping the effective dynamic mass of the recorder low so that the recorder may present a not too high inertia reactance to the record, the beam structure Il may well constitute a part of the counterbalancing structure 'Il above mentioned. Accordingly the base portion 20a of the spring 20 issecuredlby a screw .2.8 to a mounting base 21 which in turn is secured as by welding to a cross bar '2l `forming a part of the counterbalancing structure il as shown in Figure 2. This cross bar is secured'by screws 29' to a,U-shaped bracket 3l which is pivoted, as at l5, t0 a boss 3| extending down from the frame 4 of the recorder. Enclosing the beam structure from the atmosphere, to `conserve the slab 2i of damping material, is a casing 32 which snugly fits the mounting base 21 and which is retained thereto as by a screw 3l.

.In the arrangement here described it is'seen that .the vibration absorber (which includes the beam structure I0 and weight 23) and the casing 132.

and supporting means for the absorber '(which.

supporting means includes the mounting 21, the cross bar 2l andjbracket l0) are all included within the counterbalancing structure Il In-t'he present instance there are employed -two I or the damped -vlbrauonabsorbera which albksorbetshave'theirranalogous portions represented, by identicalv reference characters.` -abi .tion absorber is one having a temperature-resonant frequency characteristic which is substantially similar to the temperature-resonant frequency characteristic of the recorder throughout the operating range of temperatures, this range typically being from 50 F. to 90 F. as aforementioned. With such arrangement there will be preserved at each discrete temperature within this range a substantially fixed ratio of tuning between the damped vibration absorber and the resonant frequency of the recorder, thereby maintaining the damped vibration absorber at its optimum eiiiciency. Such a temperature-resonant frequency characteristic of the vibration absorber will be realized provided the compliance Aof the beam structure I9 varies with temperature in substantially the same way as that in which the effective compliance between the' re'- corder and the moving record varies.

I have found that there is `available armaterial which has a compliance that varies with temjperature in substantially the manner just noted throughout the temperature rang'efrom `50" F. to 90 F., and that this material has, moreover, a considerable internal resistance. This material is a synthetic rubber known by the trade name of Neoprene In adapting a slab of this temperature-resonant frequency characteristic substantially conforming to that of the recorder throughout the 'operating temperature range from 50 l". to 90 F. It is found that these two known by the trade name of Du Pont"Viscoloid. While this damping material has the advantage of high internal resistance it has the disadvantage, in the present application, that its compliance varies with temperature at a rate much faster than that of the effective compliance characterizing the 'action between the recorder and the moving record. If a beam structure were, for example, made up by applying a slab of this damping material to a relatively thin ,spring (as in the manner above described in connection with "Neoprene) to` form a structure wherein the damping material constitutes the principal stiiness-controlling element, this structure would have very good damping capabilities; but it would have a fast rate of change in its resonant frequency with temperature because .of lthe steep temperature-coniplianc'e characteristic of the damping material to the beam structure above described I make the spring 20 relatively'thin so that it will contribute little to the stiffness of the structure, thereby permitting the. slab of Neoprene to be .the controlling factor in the determination of the i temperature-compliance characteristic of the beam structure. ``Everi though the spring 20 is made relatively thin, it yet has several very desirable actions: First, it

. prevents cold ow (i. e., permanent deformation) 'in the slab of dampingmaterial, and second, be-

cause of its channelled end portions, it definitely determines the active length of the slab of damping material and provides ready means by which the damping material may be supported at one end and suitably loaded at the other withoutcritical effect Aupon`the compliance of the beam mined frequency intervals, the intervals being substantiallyv twice the permissible variance in relative tuning between one of the absorbers and the recorder while yetpreserving the effectiveness of that absorber.

Thus it is seen that while a beam structure forned principally of Viscoloid has high damping capabilities, it is not particularly well suited as a vibration absorber for the suppression of the effects arising from the temperature-varying resonant frequency of the recorder, because such a beam structure has aresonantfrequency which varies with temperature at a rate much fasterl than that in which the resonant-frequency of the recorder varies. I have found, however, that damping materials generally,l particularly those having high damping capabilities and high ratio of change in compliance with temperature,v such as is characteristic of Viscoloid may be employed in a manner to produce beam structures this occur, the effectiveness of the absorber may,

however, be increased by increasing the .width of the beam structure I9. Such increase fifn width will increase the stiilness and the effective mass of -the beam structure.- This increase in stiff-v ness and mass of the beam structure will, how-4 ever, be in the'same degree and be Iwithout eect tain the proper relative tuning. A.,widening of the structure may also be accomplished, in

effect. by the use of a plurality of similarJ beam structures. iin the present case I have resorted to Nthe latterexpedient, there being employed y.two identical beam structures each having a having any preassigned lower rates of change in their temperature-resonant frequency characterf istics; and vmoreover that these beam structures will yet exhibit the damping capabilities of the damping material itself to considerable degree,

' depending upon the difference between the tem- 'indenne system to which nieaianieorber,y 1s eppned.

and thereby preserve the effectiveness of the abcombined action will result ln'an eective supsorber through increased ,ranges of temperature.

, Since metals have a compliance essentially unresponsive to temperature, within the range of present interest, it is found that beam structures comprising a combination of metal and damping material` (for example, one of the general form hereinabove described) may be designed to have temperature-compliance characteristics predetermined within the range between that of the metal itself and thatof the damping material itself, depending upon the proportioning 'of metal to damping material. As the ratio of metal to damping material is increased the damping pression ofthe 4recorder resonance.` It will be seen that in the arrangement just described I have employed a commercially available damping materialy in a vibration absorber in a manner to obtain a wide temperature coverage capabilities of the beam structure so formed will be reduced. However, when a material of high damping capabilities such as "Viscolo id is used in the beam structure, I find that by a proper proportioning of metal to damping material the temperature-resonant frequency characteristic of y the beam structure can be made to conform closely to that of the recorder through a wide range of temperature while yet retaining in the beam structure sufficient damping capabilities vto preserve the' effectiveness of the absorber throughout such temperature range. Thus by the expedient of combining metal and Viscoloid or other commercially available materials of high damping capabilities, I may form a beam structure for a vibration absorber which will effectively suppress a temperature sensitive frequency-varying resonance through a temperature range considerably increased lover that in which a beam structure made principally of such damping material will be effective.

In utilizing combined metal-viscoloid beam structures of the type just described I find that a single vibration absorberU employing such struc- -tures will effectively suppress the recorder resonance through substantially half of the entire operating temperature range of from 50F. to 90 F., and that two such vibration absorbers when properly relatively tuned will by their combined action cover easily th'e entire operating temperature range. To effect such proper relative tuning the absorbers are respectively tuned, at a mean ambient temperature of say 70 above and at this temperature, the tuning being done for ciple I may employ; in absorbers, damping ma'- example by adjusting the weight 23 along theV spring 20 into relative positions such as is indicated in Figure 6. The mistuning of the absorbers relative to the recorder is, however, restricted so that the combined or straddling action of the two absorbers will just effectively suppress the resonance effects of the recorder throughout the region of the mean temperature. In the temperature range below the mean temperature above noted, the resonant frequency of one of the absorbers will with temperature change approach,

with a limited number-of such absorbers. This was accomplished by employing a plurality or multiplicity of predeterminately differently tuned beam structures wherein the ratio of metal to damping material is substantially the maximum permissible while yet retaining in the beam structures effective damping action. WhileIobtain particularly beneficial results by a multiple arrangement of carefully relatively tuned Abeam stmotures of the type just described, it will be understood that in accordance -with this multiple-absorber aspect of my invention, I am not necessarily limitedwith respect to the type ofindividual beamstructure employed. I may, for example,` employ lower ratios of metal to damping material, or even beam structures comprising i principally the damping material alone, and yet obtain efficient suppression over a very material temperature range by employing multiple arrangements of such beam structures as when the structures are carefully differently tuned. Moreover, it will be understood that in accordance with the principles herein disclosed in regard to multiple arrangements of vibration absorbers, my invention does not necessarily contemplate an absolute change in the frequency of the resonance to be suppressed but rather a relative change with temperature between such resonant frequency and the natural frequency of the respective vibration absorbers; and that on the basis of this printerials having steep temperature-compliance characteristics and yet suppress through wide temperature ranges an essentially constant-frequency resonance by means of a limited number of such absorbers respectively differentlyituned at predetermined frequency intervals.

y In Figures '7 through 11 there is shown the application of the damped vibration absorber oi' my invention to an electrical phonographicrecorder. Such a recorder may comprise an oblong frame 35 having a converging end portion 35' (see Figure 8) and a ange 3l extending downwardly along its sides to form a shell-like structure. In the converging end portion 35 of-the frame there is provided the recorder proper' which, by way of example, is shown in the form of a triangularly-shaped piezo-electric bending unlt31 of the so-called bi-morph type-e. g.,

comprising two'thin crystals secured face-to-face and arranged for simultaneous voltage application thereto by way of leads 38 to cause one crystal to expand longitudinally as the other contracts, and vice versa, whereby-to result in a bending of thev unit. The bending unit 31. is

cantilever-mounted between two similar trap'e- I' zoidally-shaped plates 4I which have base porj tions 4I' of increased thickness bearing against the base portionl of the bending unit.; the remaining portion o f the unitis. left free for vibration in accordancev with electrical oscillations im-I pressed on the leadsv 3l and on the free end -of f `by four screws 42 ywhich are located beyond the bending unit at the' corners of the plates".

that their. Each of these screws pass freely through the' top of the frame 35 and through the upper one of the plates Il'. The two screws-which are at the free end of the unit however thread into the lower one of the plates ll while the other two screws, the ones in the base portion of the plates flanges 36, 'are-pivot screws l1 having conicalend portions which engage respectively with a pair of spaced arms It'. These arms extend upwardly through an opening I! in the top of the frame 35 and thereafter converge into a shank 50 of a support for the recorder.

For the purpose of 'suppressing or mitigating resonance effects of the bending unit itself, and for safeguarding the unit from excessive strain such as may be occasioned by improper handling of the recorder, there is provided a pair of resilient pads I, made. for example of rubber, which are interposed at the free end of the bending unit between the unit and the upper and lower plates respectively.

This electrical recorder, the same as the acoustical recorder hereinbefore described, is biased by its own weight to maintain a normal coaction between the recorder stylus and a record R which may, for example, be of cylindrical shape. During recording the record R is rotated and the recorder is progressively moved therealong as by a suitable driving means, which driving means is however not herein necessary to show. Movespectively at opposite sides of the frame, The absorbers may be mounted vlin this manner, and may be moreover enclosed from the atmosphere so as to conserve the damping material employed in the absorbers, by a mounting means in the form of a cylindrical container M which in length is adapted to .ilt between'the side anges Il oi the frame Il.

The container 54 comprises a tube-5i having counterbored ends .into which are iltted relatively thick end walls 5B. The container is held on the frame l5 by means of screws 51 which pass through the side iianges 3B and thread into the end walls. .The end walls 56 are similarly shaped and respectively provided on their inner sides with recesses-58 forming'bases oil'set from ment ofthe recorder from the record, for examy the coaction between the 'recorder stylus ll 'and the moving recordy and the compliance of the bending Nunit 31, and (b) the eil'ective mass, as seen oy the record, oi the entire recorder. the frequency region of this. resonance the recorder may become inordinately highly sensitive as in the manner heretofore described in vconnection with the acoustical ltype of recorder;

the center of the end walls on which the vibration absorbers are respectively clamped as by the screws Il; the end walls are, however, oriented 180 from each other about the longitudinal axis of the container, so that the vibration absorbers will clear one another and have their movements commonly directed, andiboth end walls are oriented relative to the frame 3i so that the direction of movement of the absorbers will be substantially tangential relative to the path of the pivotal movement of the frame 35 on its supporting arms.

Although I have shown an'd described my in- -vention in terms of several speciilc embodiments it will be understood that these embodiments are merely illustrative and not limitative of my invention, and that these embodiments are subject to many changes and modifications without departure from the .scope of my invention, which I now undertake to express according to the following claims. 5

I claim:

1. In an oscillation translating system having a vibratable member, and means associated with said member and having a temperature-varying characteristic tending to produce with said member a frequency-varying resonance; a damped vibration absorber applied to said member to cause said resonance to be suppressed throughout a predetermined temperature range, comprising a resilient beam structure including two disand, as in the'case of the acoustical recorder,"

the frequency of this resonance will varywith temperature because of the temperaturefvary'ing characteristics of the record material. To suppress eiects of such resonance I may' employ damped vibration absorbers which may be in -the frame 35 and mounted in counterbalancing arrangement relative to the\ recorder proper.

-The preferred mounting arrangement for these vibration absorbers is one in which thebesm structures of the absorbers are mounted transverselyof the frame 'al with their base ends re- 75' tinct resilient portions respectively having compliances varying with temperature at relatively low and high rates, said portions being associated with one another Vand having a predetermined proportional relationship to cause their combined Y ated with said vibratable member and comprisa .plurality of distinct resilient portions respectively having compliances varying with temperatu're at diiIerent rates, andthe combined compliance of said portions varyingrwith temperature throughout a substantial ,temperature range in a degree to maintain throughout said temperature range a substantiallyiixed ratio of tuningbe'tween the natural vfrequency of'said absorber and the frequency of said resonance.

3. In an oscillation translating System having temperature:- a damped vibration absorber for .l

' audace causing said resonance to be suppressed throughl out a predetermined temperature range, comprising a multi-layer beam structure having a layer of material of high resilience relatively in sensitive to temperature and another layer of material of low resilience highly sensitive to tem-A y perature, and the dimensions of said layers being proportioned to maintain throughout said terrik perature range a substantially fixed ratio of tuning between the natural frequency of said beam structure and the frequency of said resonance.

4. In an oscillation translating` system having a vibratable member characterized by a resonant tendency varying in frequency withl temperature: a damped mechanical oscillating structure applied to said member to cause said resonance to be sup-v pressed throughout a predetermined temperature range, comprising ,a bi-layer resilient beam and a localized mass mounted thereon, one layer of said beam consisting of a material having a resilience substantially` insensitive to temperature and the other layer of said beamconsisting lof a material having a high internal resistance and a' resilience relatively highly sensitive to temperature, and the relative dimensions of said layers being proportioned to `maintain throughoutsaid temperature range a substantially fixed ratio of tuning between the natural -frequency of said beam and the frequency of said resonance.

5. In an oscillation translating systeme: the combination of a vibratable member; and means effective to suppress vibration of said member,

8. .In an oscillation translating system' having a vibratable member characterized by a resonance varying in frequency with temperature: means for causing said resonance to be suppressed throughout a predetermined temperature range comprising a plurality of damped vibration absorbers each applied to said vibratable member and each having a natural frequency varying in frequency with temperature in the same direction but to a different degree from that in which the frequency of said resonance varies, said absorbers being characterized by optimum effectiveness when their natural frequencies -bear a predeterf mined ratio to the frequency of said vibration, and the tuning of said absorbers "being at frequency intervals whereby to cause at least one of the natural frequencies of said absorbers to bear y at least approximately such ratio to the frequencyl of said resonance at any temperature within said range.

9. Inan oscillation translating system having a vibratable member and means associated with said member and having a temperature-varying characteristic causing a frequency-varying resonance with said member: the combination of means forv suppressing said resonance throughout a predetermined temperature range, comprising comprising a vplurality of damped vibration absorbers each applied to said member and each including a resilient `structure having a compliance varying with temperature and causing the natu' ral frequency of the absorber to vary with temperature in relation to the frequency of said" vibration, said absorbers being characterized by optimum effectiveness when their frequencies bear a predetermined ratio to the -frequency of said vibration, and the tuning of said absorbers being at frequency intervals whereby to cause'at least one of the natural frequencies of said absorbers to bear at least approximately said predetermined ratio to the frequency of said-vibration at any temperature within 'a substantial temperature range. Y 6. In an oscillation translating system: the combination of a vibratable member in said system; and means for suppressing vibration of said member, comprising a plurality of tuned damped vibration absorbers each effective on said member and each having a resilient portion characterized by a compliance varying withtemperature and causing the natural frequencies of the absorbers to vary in relationto the frequency of vibration of said member, and the tuning of said absorbers being at predetermined frequency intervals.

' 7. In an oscillation translating system: the

combination of a vibratable member; means associated with said member and having a temperature-varying characteristic tending to produce a frequency-varying resonance with said member; and means to suppress said resonance comprising a plurality of damped vibration absorbers effective on said member and each including a resilient beam structure having ,a compliance varying with temperature and causing the natural frequency` of the beam structure to vary with temperature in relationr to the frequency of said resonance,

said beam structures being successively tuned tol the frequencies attained by said resonance atpredetermined temperature intervals progressively spaced.

a plurality of predeterminately differently tuned damped vibration absorbers each effective on said member and each actively including a resilient beam structure vcomprising a slab of damping material having a compliance varying with temperature and causing the natural frequency of the sla-b to vary at a substantially faster rate than 'that in which the frequency of said resonance varies, and means applied to said' respective slabs and opposing the variation in compliance of saidV slabs whereby to cause the difference between the rate of variation in the natural frequency of each beam structure and of said resonant frequency to be substantially less than the difference between the rate of variation in the natural frequency of each slab of .damping material and said resonant frequency. A

10. In a phonographic translating device: the combination of a movably mounted holder; a vllbratile means supported by said holder for'coaction .with a moving record, said coaction tend- )ing to cause a resonance between the holder and the moving record the frequency of which varies with temperature of the record; and a tuned damped vibration absorber coupled to said holder and effective as to vibrations of said holder relative to the record, said vibration absorber having a resilient beam structure-comprising a damping material having a compliance varying with temperature throughout a predetermined range land causing the natural frequency of the damping -material to vary at a substantially faster rate than that in which the frequency of said resonance varies,l and a resilient material having a compliance substantially unresponsive to tem' perature and applied to said damping material in a proportion to maintain a'. substantially fixed ratio of tuning between the natural frequency of said beam structure and the frequencyof said resonance throughout said temperature range.

11. In a phonographic translating device: the

combination of a movably mounted holder; a vibratlle means supported by said holder for coaction with a moving record, said coaction tending to cause a resonance between the holder and the moving record the frequency of which varies with temperature of the record; and a damped vibration absorber for suppressing'vibration of said holder within a predetermined temperature range, comprising a resilient beam structure having two distinct portions, said portions respectively having compliances varying with temperature at relatively low and high rates, and said portions .being combined in predetermined proportional relationship to cause said absorber to have a frequency-varying resonance approximating throughoutv a substantial -portion of said tem` perature range the frequency of resonance between said holder and moving record.

12. In a. phonographic translating device: the combination of a movably mounted holder; a vibratile means supported by said holder for coaction with a moving record, said coaction tending to cause a resonance between'the holder and the movingv record the frequency of which varies with temperature of the record; and means for causing vibration of said holder to be effectively suppressed at all temperatures within a predetermined temperature range, comprising -a plurality of damped vibration absorbers each including a damped beam structure having a compliance varying with temperature and causing its natural frequency to vary at a rate different from that in which the frequency of said resonance varies, said beam structures being respectively tuned to the lfrequencies attained 4by said resonance at .pre-

determined temperature intervals progressively spaced Within said temperature range.

13. In a phonographic translating device: the combination of a movably mounted holder; a vibratile means supported by said holder and coacting with the surface of a moving record', said coaction tending to cause a resonance between said holder and record the frequency of which varies with the temperature of the record: and means for causing said resonance to be suppressed throughout a .predetermined temperature range, comprising a plurality of predeterminately differently tuned damped vibration absorbers each coupled to said holder and each actively infrequency ofsaid resonance varies, and means in damping means effective on said element said respective beam structures applied to the damping materials thereof for causing the difference .between the rates of variation of the natural frequencies of saidbeam structures and of said resonant frequency to be substantially less than the difference between the rates of variation of the natural Vfrequency of said damping material and said resonant frequency.

14. In an oscillation translating system: a vibratable element forming a portion of said system and subjected to a vibratory influence; and damping means effective on said element to sup- .press vibration thereof, comprising a spring having a distinctly dened resilient portion interposed between relatively stiff inner-end and outer-end portions, said inner-end portion being secured to said element, a localized mass mounted on said outer-end portion, and a damping material retainedin contact with said spring along said resilient portion.

15. In an oscillation translating system: a vibratable element forming a portion of said system and subjected to a vibratory influence; and damping -means effective on said element to suppress `vibration thereof, comprising a beam secured' to land extending from said element and having spaced -channel-shaped portions along its length; and a slab of damping material applied to said beam along the portion thereof between said channel-shaped portions.

16. In an oscillation translating system: a vibratable element forming a portion of said system and subjected to a vibratory influence; and to sup press vibration thereof, comprising a beamv secured to and extending from said element and having spaced channel-shaped portions along its length; damping material applied to said beam along the portion thereof `between said channelshaped portions; and means on said channelcluding a resilient beam structure comprising a damping material having a compliance varying with temperature and causing the natural frequency of the damping material to vary at a rate shaped portions bearing against said damping material to retain the same in contact with said beam.

v 4MICHAEL J. DI TORO.

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