US2271460A - Apparatus for the production of music - Google Patents

Description

Jan. 27, 1942. B. F. MlEssNER 2,271,460

APPARATUS FOR THE PRODUCTION OF MUSIC med oct. 2z, 1940 2 sheets-sheet 1 1 maentor Jamin E'Hfrsner Jan. 27, 1942- B. F. MlEssNER APPARATUS FOR THE PRODUCTION 0F MUSIC Cltorneg Patented Jan. 27, 1942 2,271,460 APPARATUS FOB THE PMDUCTIUN F MUSIC Harding Township, Morris or to Miessner Inventions, Township, Morris County, N. J.,

a corporation of New Jersey Application October 22, 1940, Serial No. 362,192 19 Claims. (Cl. 84-236) This invention relates to musical instruments, and more ventina contemplates especially, though not in all aspects limitatively, instruments of the piano type. wherein timed Strings or other vibrators are percussively. excited by hammers under the control of a. keyboard. Ihe description will accordingly be prented largely with relation to 'a Iliana The apparatus for eiecting the excitation of been positively propelled before contact. Concomitantly introduced with the eseiiective in conjunction with apparatus specially introduced for the performance of the third of the abovementioned functions.

The later-introduced constructions to perform the third function have been arrangements to delay the fall of the hammer from its checked toits dormant position, so that the jack 0f the escapesuch as the so-called and would completely ment mechanism could restore itself to operative position under the hammer before complete key release. Typically they have comprised a socalled "repetition lever" incorporated, in the actions for grand (horizontal-string) pianos, in a complicated assembly involving adjustable tensloning and movement-limiting devices; or, somewhat less satisiactorily in the action for upright (vertical-string) planos. a particular arrangement and balancing of parts to suppress tendencies of the hammer to return to dormant position, together with special adjustably arranged means bridle-tape to enforce that return in the last portion of key release.

All these arrangements reached essentially their present stage of development approximately a. hundred years ago; and ever since then the piano action has resisted allattempts at obtaining a proper perfomance of its functions with any appreciable simplication of its construction. Unable to reduce a complexity which is actually almost appalling, the industry has simply become inured to it, and has contented itself with the mere improvement of the components of the action. methods for its manufacture, and the like.

I`have observed that the complexity of the action is actually attributable almost entirely to the escapement mechanism. It is quite true that this mechanism itself constitutes only a minor part of the complexity. But its presence is the immediate occasion of the need for the back-check. and for the entire construction resorted to for performing the third function abovementlonedfor that function would be inherently performed, disappear as one requiring special constructions, if there were no escapement.

I have further discovered that it is possible to entirely satisfactorily perform the second function abovementioned without an escapement mechanism. Prior attempts to do this have failed be.

cause of the extreme nature of the requirements. It must be recalled that the hammer must not be tripped (which term I construe and use in its broad sense, as meaning simply released or freed from the propelling force of the key) until very close to the string, for otherwise the use o1' a relatively slow key depression-necessary for a full range of touch control-will not serve to cause the striking of the string. On the other hand unless, upon tripping, the propelling means is gotten out of the way of the hammer, the rebound of the hammer from the string to that nowverynearby propelling means has occasioned an unwanted bounce of the hammer back to the string,l or series of such bounces, in either event tion of relatively Y tie-member Il appearing in Figure I have still further discovered that, in an action from which the escapement mechanism is eliminated in a manner not compromising the features of performance above noted as requisites the certainty and speed with which repetibe indulged in is not only unavailable the complete omission of the complicated mechanism specially included in the latter for the express purpose of facilitating repetition, that is, for the third function abovementioned.

Accordingly it is a general object of my invention to simplify the conventional action. And it is an object to effect this simplification without impairing the assurance of vibrator excitation with relatively slow key velocities, or the assurance of absence of bouncing of the hammer back to the vibrator after its initial rebound therefrom, or the perfection of the available repetition.

It is another object to improve the certainty and speed with which the repetition of a note may be indulged in. And it is an object to do this while greatly simplifying the action.

It is another object to provide a satisfactory action without an escapement mechanism. And it is an object to provide such an action which jointly assures vibrator excitation with relatively slow key velocities, assures absence of undesired plural contactings of vibrator by hammer, and renders available excellent repetition.

It is another object to provide such improved actions especially adapted for the excitation of relatively small and light vibrators, such as are sound.

proved actions especially adapted for the excitalight strings held under relatively low longitudinal tension.

It is an object to provide a generally simplified and improved piano action. l

It is an object to provide an improved and simplified construction for a piano, and in particular for an electronic piano.

Other and allied objects will more fully appear from the following description d the appended claims.

In the description reference is had to the accompanying drawings, of which:

Figure l is a cross-sectional view taken in a vertical front-and-back extending plane through the forward portion of a horizontal-string piano in which ,my invention has been incorporated in one form:

Figure 2 is a similar view taken through the rear portion of the same instrument, this figure also including a schematic illustration of the mechanica-electro-acoustic translating system which may be employed in this instrument;

Figure 2a is an enlarged elevational view of the Figure 3 is a vertical cross-sectional view taken substantially along the line 3-3 of Figure 1;

Figure 411s an enlargement of a small portion Flgureisaviewgenerallysixnilartosure 4 but illustrating the t of my invention in a modified form;

Fig1n'e6isaviewgenerallysimilartomgure4 but illustrating the embodiment of my invention in another modified form;

Flgureaisaview generallysimilartorlgure 4 but illustrating the embodiment o! my invention in still another modied form:

Figure? isa cross-sectionalviewtakenina embodiment of my invention in am able steel beams welded together. comprises a transverse front beam i open toward the front; a also of U-shape and open towar a plurality of front-and-back T-heams! terminally weldedtothe e 1' "afbeams. At the front (as seen in Figure l) the vertical part of each T-beam may be batted against and welded to the reato! thebeam I. and the horizontal part of each T-beam mar be extended underneath and welded to the bottom of thebeam l. Attherear (asseeninsure) the vertical part of each T-beam may be batted against and welded to the upper and lower front edges of the beam I, the horizontal part of each T-heam being extended underneath and welded tothebottomof thebeaml. The beams may be suitably inclined or tapered toward each other at the (treble) extremity of the instrument to provide the diminishinzstrnslength: thistaperinsisindicatedin the drawings, for example by the fractional showings I' andloftheupperportionsofi and 2. The rear is and held within the the front of the mest-plank. whose top maybeatalowerleveithanthtofthereerportiommay atendforwardlytoholdnminspms l.

rearbeamt thefronkand inverted be moet effective againsttheeifectoftheatringtension.

Attherearoftheframqasseinguxel there may be provided a bridge structure. erablythisisofthecanilevertypedisclosedand claimed in my cri-pending application Serial No.

229,650, tiled September 13, 1938 (on which Patent No. 2,225,195 has since been issued). It may comprise a plate 8 whose rear portion is clamped, through strips 3 and screws I0, to the inside bottom surface of the top part of rear beam 2, and extending therefrom to project forwardly beyond that beam. n the bottom of a forward portion of the plate is secured a string bridge I2. As pointed out in the co-pending application last abovementioned, the front-and-back dimension of the clamping strips B may be progressively varied transversely of the instrument, to result in a progressively varying overhang of the bridge from the clamped part of plate B, with resulting progressive variation of the compliance of the l bridge support to up-and-down vibration. Se-

cured to the bottom of plate 8 forward of the string bridge I2, and if desired integral therewith, may be a further or pick-up bridge I3 of less vertical dimension than the string bridge, the function of `the bridge I3v being hereinafter referred to.

It may be pointed out that for the purpose of accommodation to the presence of the T-beams 3, the plate 8 and the bridges I2 and I3 may be formed in sections separated from each other sulliciently to pass freely the T-beams 3. Preferably, however, these separate sections will be coupled to each other around each T-beam 3, for the transmission of vibrations transversely of the instrument (or longitudinally of the bridge) as though the elements under discussion had'not been sectionalized. This may be done for example by securing, to the extremities of the sections of bridge I3 on each side of a T- beam 3, the respective extreme portions of an inverted U-shaped tie-member Il straddling the T-beam, as best seen in the enlarged Figure 2a.

Each string 1 may pass across and bear up against the bottom surface of the string bridge I2, being held thereto by engagement with two pins Il. From the rear pins II rearwardly, and from the front pins II forwardly, the bridge surface may be bevelled, so that the terminal string contacts are right at the pins. Each front pin I I of course defines the rear end of the active portion of its respective string. From its rear pin rearwardly each string may pass, inclinedly'upwardly at an angle suitable for theY appropriate bearing on the bridge I2, to a doubly countersunk hole 2a in the vertical rear portion of beam 2, and after passing therethrough may have its extremity anchored to a pin I5 therebelow.

The particular instrument chosen for illustrative purposes and shown in Figures 1 through 4 is intended to produce its tones through the medium of mechanica-electro-acoustic translation of the vibrations of its strings, the attendant non-necessity for a soundboard permitting the employment of the simplified cantilever vibratile bridge support already described. Typical means for translating electric oscillations from the strings may include a set of pick-up electrodes IB, preferably in the form of inverted screws adjustably threaded through the pick-up bridge I3 and plate (which preferably are formed of insulating material such as Bakelite"). The heads of the electrode screws I6 may be in spaced relation to the respective strings 1, while their upper extremitiesmay be slotted for easy screwdriver adjustment of the spaced relation. In the interest of simplicity Figures l and 2 have illustrated only one string 1 and its pick-up electrode I6; but it will be understood that atleast one of each per note will be employed, as indicated for example in Figure 2a. Further as indicated in Figure 2a, some convenient means may be employed for electrically interconnecting the several electrodes, such as the conductor or soft copper wire I1 wrapped or threaded from one to another in succession above the plate 3.

A typical completion o! the translating apparatus along well-known lines has been schematically illustrated in Figure 2. Between the pickup electrodes I6 on the one hand and the striDSS of the instrument on the other there may be electrically connected in series a source 2l of electrical energy and a resistance 2| (connection to the strings being conveniently through the medium of the rear beam 2). If the source lll be operated as a high-voltage D. C. source, it serves to charge the capacity between strings 1 and the pick-up electrodes IB and, because of resistance 2|, oscillatory variations in that capacity caused by string vibration will cause a corresponding oscillatory variation in the voltage across the capacity. If the source 2I| be operated as a superaudible-frequency A. C. source, it serves to send through the strings-to-electrodescapacity a current whose amplitude, again in view of resistance 2|, will be modulated or oscillatorily varied at the string. vibrational frequencies. In either event the oscillatory components in the voltage across the strings-to-electrodes capacity may be transferred, as through a coupling condenser 22, to the input of an amplifier 23 (which, in the case of the A. C. operation of source 20. will also be operated as a demodulator). Theroutput of the amplifier 23, comprisingamplied electric oscil lations representing the vibrations of the strings 1, may be subjected to any or all forms of control known in the art, non-limitatively including control of amplitude as by potentiometer 24 operated by pedal 25, and may be further amplified and translated into sound by amplifier 26 and loudspeaker 21, respectively.

Resistance 2I and condenser 22, and the leads and terminals connected thereto, may be suitably electrostatically shielded, as schematically indicated by shielding 28 in Figure 2. Shielding of the electrodesA Ii, which is usually suflciently provided inherently by the strings insofar as ther under-side of the electrodes is concerned, may be carried out above the electrodes by a conductive plate or member 2! hinged to the top of beam 2 and extending to overhang the electrodes; this member has been illustrated in partially raised position in Figure 2.

The frame or plate constituted by beams I, 2 and 3, and thus the wrest-plank, bridges, strings, pick-up electrodes, etc., is held in the case of the instrument in some known manner not necessary herein to show, though preferably according to the vibration-insulation teachings of Patent No. 1,912,293 to me. Forming a part of the case of the instrument is the key-bed 3|. seen in Figure 1. When the front finishing rail BI is removed from the key-bed, the removable part of the action may be slid from the front into its place on the key-bed. In the form of my'invention illustrated in these gures, this removable action portion includes the usual framework 'formed by front, center and rear rails 32, 33 and 3l respectively, held in proper mutual relationship by front-and-back extending strips 35. The keys 36 are pivoted on the center rail 33 in the usual manner, and may be provided with .the usual guiding arrangements at the front, including guide pins 36a extending upwardly from front rail 32 and felt washers 36h surrounding the pins. In the illustrated form oi the invention the rearward extension of the keys proper is stopped short of the rear rail 34; but to the rear bottom surfaces of the keys are secured respective bars or members' 31 of rectangular cross-section, these extending rearwardly to overhang the rear rail 34 and normally to rest thereon through the felt or like strip 38. The bars 31 may for example be oi metal, and may serve to properly weight the key-as well as to constitute an active rear portion at a space-savingly small elevation above the key-bed.

When in position in the instrument the rear rail 34 of the removable action portion may abut (through a veryl thin felt strip 38 if desired) against a transverse vertical block 60 secured to the top of the key bed 30. To the top of the block 60 is secured a forwardly overhanging transverse horizontal block 6I. To the bottom of the latter block may be secured a felt strip E! which may form an up-stop for the etl'ective rear portion of each key (i. e., for the bar l1), the washers 36h which form the usual front down-stops for the keys being adjusted to check the key motion coincidentally with the felt strip S2. The provision of B2 as well as Sib is desirable in order that the key motion in the vicinity of the hammer shall be stopped at a discrete point, without the accuracy-impairing iniluence oi' the bowing or whipping which might otherwise take piace throughout the key length, and the like.

Attention may now be directed to the mecha.- nism interposed between each bar 31 (which has been seen to constitute the active rear portion of the key) and the respective string-this constituting a typical embodiment of the great sim pliiication of the action according to my invention. In its most basic aspect the invention is not limited as to the form of the hammer or as to its mode of movement relative to the key. I have found, however, that a very light cylindrically shaped hammer, vprovided with an appropriate head and moved simply in an axial direction toward and away from the string, is admirably adapted to the excitation of the relatively light, low-tension strings which are preferably employed in an electronic piano of the disclosed construction, and such hammers 'have been illustrated as 46 in Figure 1 and in the enlarged fractional Figure 4.

Each hammer may comprise a cylindrical side wail 41; a button or plug 4l closing its bottom extremity; and a button or plug 49 closingl its top extremity-the button 49 preferably having s top surface which is convex, and whose diameter is greater than that of the hammer side wall 41 so that a shoulder is formed therewith. These elements may be formed of any suitable though preferably light material-for example, ci aluminum or aluminum-alloy, or of plastic materail such as 'Bakelite'L-and may be cemented or otherwise firmly secured together. If desired there may be substituted, as a material for the top button 49, a material appropriate to the striking of the string, such for example as leather or hard felt, in which case the button will form the head of the hammer. I have preferred, however, and have illustrated, a covering 49d over the button 49, the button and covering then together constituting the hammer head, in which casethe special material need not be employed for 9.

The hammers may be retained for vertical axial movement in respective felt-hushed holes d! in a rail 43 extending transversely across the instrument, the heads of the hammers normally resting on a thin felt strip 45 secured on top of the rail. The desirable normal spacing of hammer-head from string (typically of the order of may require that the top portion of the rail 43 be cut away to admit the lower portions of the T-beams 3 (to the bottoms of which the rail 43 may be secured). The rail may be effectively restored to normal top level on each side oi the vertical part oi the T-beams by small blocks 44, secured on top of the horizontal portions of those beams, as seen in Figure 3. Bushed holes falling within the width of those horizontal portions are of course extended therethrough and through the blocks 44 thereabove.

Each hammer terminates at a distance above a respective one of the key-extensions or bars 31. Each key is arranged upon depression (of its forward extremity) to impart a rising movement to the hammer, and this is simply done by providing on each bar 31 below the respective hammer a capstan or hex-headed screw 40 threaded downwardly into the bar. The vertical position of the head of screw 40 is of course adjustable by rotation of the screw. While the primary purpose of this adjustability is a function hereinafter made apparent, it may here be noted that the proportioning of the parts is such that there will normally be a slight clearance between the top of the screw 40 and the bottom of the hammer, permitting theiree removal and insertion of the removable action portion.

Ordinarily the mechanism interposed between key and string comprises not only the hammer but also the escapement, checking and repetition mechanisms. For al1 these latter I substitute a bounce-suppressing means, which I have found it possible to construct in so eiective a form that the energy of the hammer, rebounding from the string, will be attenuated to the extreme degree necessary to preclude bouncing of the hammer back to the string-even though the distance through which the rebound occurs, and through which a bounce would bring the hammer back into the repeated contact with the string, be only a tiny traction of the total original hammer stroke. Such a result has hitherto been thought quite incapable oi achievement; and so it is, ii there be relied on simply the absorption of hammer energy occurring in a pad or the like against which the hammer rebounds and which is made of one of the felt, leather or like materials which in piano construction are always resorted to for the performance oi' shock-insulating and similar functions. (Such materials are in their general nature iibrous; their largely inter-secured iibres, following deformation of the material, tend to restore themselves to original arrangement with very little work; and their reactions to defamation are therefore essentially resilient rather than energy-absorptive.)

I have found that. satisfactory bounce-suppressing means may be constructed according to either of two principles. though I prefer one in which both principles are aptly combined. One principle is that of energy oppositionby a mass moved at appropriate times into opposing impact against the mass of the hammer (or, when this mass is a part of the hammer, into opposing impact against the residual mass of the hammer). The other principle is that oi energy absorption-but with a material o! an entirely dinerent Aorder oi' effectiveness from those abovementioned.

I may here note that the type o! energy-absorptive material which I have found to have the entirely different order oi eiiectiveness is one whose deformation and restoration involves much work; it may '.'generally be described as an effectively uid mass characterized by a high viscosity. I use the*V term mass" rather than substance" to indicate that the fluidity represents a relative movement oi particles oi the material, whether those particles be the molecules oi' a truly fluid or semi-uid substance, or individual larger particles oi a solid substance which together form an agglomerate mass. I use the term viscosity in its accepted sense as to ilulds and semi-fluids, and in its obviously equivalent sense as to an agglomerato. By way of examples oi such a mass of essentially uid or semiiiuid substance may be'mentioned masses of tar, Viscoloid, gum (for example in such form as candy gum drops), jelly, putty, plasticized clay, oil, natural resins, synthetic resins, etc. By way oi examples ci such a mass oi' individual solid particles may be mentioned agglomeraties of sugar, salt, sand, iine gravel or stone, carbon granules, lead or other metallic particles, and the like. 1t will of course be understood that the foregoing examples are presented simply to show typical kinds of material ofthe general nature to which I resort, and have not been set forth with any eiort at special arrangement in-respect of their relative viscosities--which may vary considerably with precise chemical compositions (as in the case of uids or semi-iiuids). with particle size (as in the case o the agglomerates) and with other factors. It will also be understood that the best choice oi a preferred material depends not only on available high visclty, but on ease oi handling and embodiment in the construction otherwise contemplated, imperviousness in that construction to chemical or physical change or deterioration with time or use, and the like.

The embodiment o! my invention illustrated in Figures l through 4 utilizes jointly the two principles abovementioned. They are made eiective therein simply by the illllng oi the hollow hammer 4B. preferably to a maior fraction 0i its height, by one of the materials abovemenhoned-preferably one oi the agglomerates, such as ilne gravel. The special and salutary eects for which this simple structure is responsible will become apparent from a consideration ol the operation of the action.

'As key depression is begun the screw ln will almost at once be brought up into contact with the bottom oi the hammer It. As key depression is continued the hammer, its bottom now driven by screw 40, will be propelled toward `the string. Very slightly before the hammer head l! reaches the string the key motion will be stopped by impingement o! 31 on il. The momentum of the moving hammer, however, causes it to continue its movement: and since it is now tree oi connection with the key, it may in a broad sense be said to have been tripped. Travelling the slight distance from tripping point to string, the hammer strikes the string and rebounds downwardly therefrom. The element which drove the hammer upwardly-the screw A D-has not been displaced laterally from its driving path by any escapement nor has it been retracted downwardly (unless in the exceptional case of extreme stacatto key manipulation). It theretore occupies the position it had when the hammer was tripped: and accordingly the distance o! tree rebound oi the hammer is only equal to the small distance oi' its original movement alter trinnins.

Inthe absence of the special features of my invention, the hammer, striking the screw 40 at the conclusion oi its very short rebound, would bounce upwardly again through the same small distance to strike the string a second time.V Indeed. i! the original key velocity had been at all great, the hammer might repeat the reboundbounce cycle, or string-to-screw oscillation, several times, and thus cause a third or even iurther strikings oi the string. But there are two eii'ects of the eiectively nuid mass ill whichy severally and iointlyvact to suppress this bounc- During the upward movement of the hammer this mass, already urged by gravity to occupy the lowest possible position within the hammer, undergoes little movement withlh itself or relative to the hammer. But when the hammer movement is stopped and reversed by its striking oi and rebounding from the string, the momentum oi' the mass lil causes it to continue upwardly into impact against the bottom (interior) surface of the hammer head 49. In view of the effectively fluid nature oi the mass 49, this impact will not be entirely discrete, but will be effectively distributed over a minute time interval. By proper choice oi' the extent to which the filling of the hammer is carried, this impact or at least the principal 'portion thereof is readily caused to occur during the rebound of the hammer-i. e., after it has begun its rebound from the string but before it has come back into impingement against the screw 40. 'Ihis impact oi the upwardly moving mass 5U against the downwardly moving mass of the hammer oers an abrupt opposition to the kinetic energy of the latter, a large percentage of which is thereby dissipated in the form oi heat attendant on the impact. The hammer thus reaches the screw III with much of its kinetic energy already dissipated by the described impact.

The first effect does not stop here, however. By the end ofthe hammer rebound the mass Sli `has come to occupy essentially the highest possible position within the hammer, and is moving downwardly with the hammer. When the downward hammer rebound is stopped by the screw l0, the momentum of the mass B0 causes it to continue downwardly into impact against the top (interior) surface of the hammer bottom 48. This impact or at least the' principal portion thereof will occur well before there has been completed any string-ward bounce oi' the hammer which tends to result from such kinetic energy as the hammer may still have after the earlier (above described) impact-dissipation. This second impact of the mass til, now moving downwardly and directed against the hammer now tending to move upwardly, oiers an abrupt that the :continued key depression will raise the upon key release. It will of course be understood that the impedance which it is' desirable to add by an arrangement of this character is at maximum of a relatively small magnitude. and that the constants of the springs l will be chosen appropriately to this fact.

In connection with the screw 10a, there may be noted an advantage of employing this as a sole means for retaining the bar 31 against the bottom of the key proper. This advantage is that the bar may then be subjected to any slight lateral adjustment (about the screw as a pivot) which may be necessary to accurately align the energy-absorbing device l with the bottom of its respective hammer. The screw lla may for example be threaded through the bar l1, and after tightening the bar in any desired adjustment may be locked by tightening a lock nut b against the bottom of the bar.

In the description of operation incorporated above there has been no special mention of the operation as to repetition, or upon the re-depression of the key after an incomplete release thereof. But since the hammer bottom comes essentially instantly, after string striking, into a renewed continuous contact with the screw lil (that is, continuous subject only to the inconsequential exception of the very slight spacing when the key is fully released), it will be apparent that the action is inherently adapted to perfect repetition with just as minute a degree of key release as will provide any opportunity at all for signicant re-depression. Simply stated, the otherwise always present problem of providing for satisfactory repetition has been not Amerely solved, but altogether eliminated as a problem, in connection with the elimination oi the escapement.

The instrument of Figures 1 through 4 has so far been described without reference to the usual string dempers, or vibration-terminators. These may of course be provided, fundamentally in the customary arrangement of normally resting on the respective strings, being respectively raised therefrom by depression of the respective keys, and being all raised as a unit by depression of an appropriate pedal. I have, however. incorporated the dampers in this instrument in a particularly simple manner, which may now be described.

The dampers may comprise suitable felt pads 1I, respectively secured to the bottoms o! blocks 12. Inthesideofeachblockmaybesecuredthe upper extremity of a respective damper rod 13. At some distance below the bottom oi its damper pad 1l each rod 'Il may beprovided with an oil'- set 13a. to substantially align below the respective string the portion of the rod which lies below the onset. This lower portion of each rod may pass through a respective felt-hushed hole 14 in a damper rail 1I. which may for example be conveniently formed as a rearward extension of the lower and middle p0rtions of hammer rail Il: when the damper rests on the string the respective rod odset 13a may be slightly above the top of the rail 16. From the rail 15 the rods 13 may extend downwardly to terminate slightly spaced above respective hard felt or other durable pads 1l. which are respectively securedontopoi'theseveralbars'lbehind the devices Il. It will be understood that the ver! nrst part of key will bring the respective felt pad It into impingement against the bottom of the respective damper rod, and

respective damper from the' string.

To retain the dampers against rotation about their rods 13 I employ a simple arrangement which may comprise a respective pin il extending forwardly from` each damper block 'I2 into a respective vertical slot 18 cut in a transverse vertical plate 19, which by reason of the several slots 18 therein may be likened to a comb with upwardly directed teeth. The top of the plate or comb-member 19 may be clamped between the iront and back portions of a rail B0, disposed diagonally forwardly of and above the dempers. By this simple arrangement the dampers are retained against rotation without recourse to the specifically pivoted individual damper ilanges and attendant parts customarily employed.

A limit for the upward movements of the dampers, so that they will not appreciably overshoot their intended rise by reason of momentum developed on faster key depressions, may now be asociated with the dempers themselves. This .may consist simply in a felt or like strip 82 secured to the bottom of a rail BI which may be ilxedly mounted at a suitable elevation above the dampers.

To lift al] the dempers at once from the strings, a suitable pivoted pedal such as 83 acting through rod 84 may upon depression lift the rail 80 and thus the plate or comb-member 19. It is to render this plate-lifting eifectivelon the damper pins 11 that the slots 18 are not cut through to the bottom of the plate 19, but that instead the bottom portion of the plate is made transversely continuous, with the pins 11 normally disposed slightly thereabove. To establish a proper path for the limited upward movement of the rail Bil by the pedal, arms such as 85 may be secured to the rail and may extend a distance rearwardly therefrom to fixed pivots such as B6.

It will be understood that while I have specially mentioned one of the agglomerates as a typical material for the effectively iluid mass 5l in connection with Figures l through 4. there may be substituted therefor a semi-fluid or fluid-preferably the latter, since the very restricted space in which it is employed in this embodiment tends to require a reasonable uidlty so that the desired movements will actually occur. Figure 5 illustrates this modification, the mass ln question appearing as 6I therein, and comprising for example an oil of quite high viscosity.

While I prefer to rely on the joint action of both of the effects discussed above, I may rely wholly or almost entirely on the first. or opposing-impact. one alone.` In such a case, for example, the effectively fluid mass lill may be replaced by a discrete mass. This I have illustrated in Figure 6, wherein the hammer proper may again be as in earlier figures, but wherein there is provided internally thereof a solid rod I2 of length somewhat less than the internal hammer length.

lf desired, at the ends of this rod there may be provided deformable bumpers" of viscous material, so that there will be an energy-absorbing action supplementing the opposing-impact action at least at and about the instants of those impacts. A bumper I3 carried by the rod I2 is shown at the top of the latter. This may for example comprise a small approximately hemispherical mass lla of viscous material, preferably one of the semi-fluids; and, to prevent any possible sticking as well as to provide a slight but denite urge to restoration after deformation, a very thin covering 53h oi' rubber stretched over it and securing it to the rod. A similarly active bumper 53, this one for example loose within the hammer below the rod 52, is shown as comprising the very thin rubber sphere 54h iilled with the mass 54a of viscous material.

A better supplement to the opposing-impact action of the discrete mass or rod 52 may be provided be a means offering an energy-absorbing action-preferably a viscous one-during all movements of the mass 52 relative to the hammer proper, instead o! merely upon its impacts. While such a means may take a variety of forms, it is very conveniently provided by a filling of oil or the like within the hammer surrounding the rod 52. Such a filling has been illustrated as 55 in Figure 6 in addition to the bumpers 53-5l, though it will be understood that ordinarily one or the other, rather than both, these expedients would be employed.

Particularly if the diameter of the mass or rod 52 be made almost as great as the internal diameter of the hammer proper, the oil filling need not be a complete one. Thus in Figure 6a I have shown the mass or rod 52' (with which no bumpers are illustrated) surrounded with only a very small quantity of oil 55' This produces a structure which I have found especially effective.

Particularly in the constructions of these Figures 6 and 6a, it may be noted that the movement of the loosely carried mass (e. g., 52') upon hammer impacts may not always extend to produce an impact of the mass against the hammer. This, however, does not preclude an eil'ective action; for the movement of the mass which does occur deforms or internally moves the viscous material (e. g., oil 55'), which is very effective to absorb the energy of the hammer.

In Figure '7 I have shown another embodiment of my invention, in a piano which may for example also operate electronically, but which is of upright or vertical-string arrangement. Its general construction, illustrated for simplicity in a single figure (Figure 7) without attempt to indicate tapering of the lengths of progressive strings, may first be brieby described. The plate or frame is again formed of suitable steel beams welded together, but the transverse beams have been shown by way of variation as of L-shape; these are the top beam and the bottom beam |02, the vertical portion of each beam extending upwardly and the horizontal portion forwardly from the angle therebetween. T-beams |03 may extend between the beams |0| and |02, their central cross-sectional portions being forwardly directed and terminally butted against and welded to the. horizontal portions of |0| and |02, and their cross portions being butted against and welded to the vertical portions of |0| and |02. The wrest-plank |03 may be disposed within the angle of beam |0|, and may hold the forwardly extending tuning pins |05; from them the respective strings |01 may pass downwardly over a ledge |0|a which may be formed by the i'orward edge of beam |0| and which defines the upper extremity of the active string length.

The string bridge H2, whose rear portion may be extended upwardly to form a pick-up bridge I3, may be held in front of the vertical portion of the bottom beam |02 near the top of the latter. To provide for vibratility of the bridge there may be interposed between it and the beam |02 a strip |00 of resilient material extending transversely oi the instrument, the front and back surfaces of this strip for example being cemented to bridge and beam respectively. If desired. as a means of damping the bridge vibration and hence increasing the rate of damping of the strings, the strip |00 may be split longitudinally and between its two portions there may be interposed a strip or mass |00 of one of the errectively fluid, viscous substances abovementioned (preferably one of the semi-fluid materials), the front and back surfaces of this material |00 contacting the bridge and beam respectively. The strings |01 will of course pass over the forward face of the bridge, engaging bridge pins and may pass on down to terminate in respective pins I5 extending forwardly from the front edge of beam |02. The parts will of course be apportioned to provide a proper rearward bearing of the strings against the bridge, so that the strings supplement any other means employed in holding the bridge in the illustrated and described position. The bridge and associated transverse elements (e. g., |00, |09) may of course be interrupted at the beams |03; but the bridge may be unified for the whole instrument by tiebars Ill straddling those beams (analogous to I4 of earlier figures), preferably secured to both top and bottom bridge surfaces.

The translation of string vibrations into sound may be effected by any appropriate translating apparatus; for example a system similar to that oi earlier figures may be employed, and this has been schematically illustrated by the showing of the pick-up electrode H0.

The key bed |30, forming a part of the case of the instrument (in which the unit formed by the elements already described is of course appropriately held), supports the removable part of the action. This part may be very generally similar to that described for earlier figures, and has been shown as including the center and rear rails |33 and |34 and the front-and-back extending strips |35 holding them in proper relationship; the keys |35 pivoted on |33; and the bars |31 conveniently employed as the rarmost portions of the respective keys and normally resting on rail |30 through felt or like strip |30.

With the vertical strings of this embodiment it is convenient to employ pivoted hammers. To provide a suitable pivoting support therefor, a rail |43 may be ilxed slightly in front of the strings and above the rear extremities of the bars |31; this rail may for example be held by the top extremities of screws or posts |62, whose bottom extremities may be secured in the key bed |30 and which may pass upwardly therefrom at suitable intervals. The forward portion of the hammer rail may conveniently be employed in forming a rear up-stop for the keys; accordingly a felt strip |02 may be secured to its bottom, to be in ipinged on-by the rear portions of the bars |31 upon key depression.

The hammers |40 for this embodiment may be very simply formed from at, light metal strip, bent into a closed form eievationally approximating a triangle. The rear end of the base of the triangle may form the pivoting point: and the pivoting may be carried out by a suitable cloth strip |45 folded back on itself at this point. one fold of the strip being secured to the bottom of the hammer base and the other to the top surface of the hammer rail |43. Normally. since the center of gravity of the hammer lies forwardly of the pivoting point, the top fold of the strip |05 will be closed against the bottom fold, as uiustrated. establishing a manual position for the hammer. From the pivoting point the rear leg of the hammer may extend upwardly for a distance, and may then be formed to have a rearwardly directed, rounded surface or head Ilia over which may be secured a piece III of leather or other suitable string-contacting material. From the rounded surface Illia the forward leg of the hammer may extend diagonally downwardly and forwardly to join the forward portion of the base of the hammer forwardly of the rail M3, completing the approximate triangle; the extremities of the forward leg and the base may be held together and bent to form a horizontallug Mib. The top surface of the hammer rail |43 may conveniently slope downwardly to the front, so as to bring the lug Mlle reasonably close to the top of the bar |31 when the hammer occupies its normal position. Downwardly through this lug llllb there may be adjustably threaded a screw IIS.

I pointed out above that for bounce suppression I might rely entirely on the principle of energy absorption with the effectively fluid, viscous materials, and without the use of the opposing-impact principle which has been present in the embodiments through Figure 6. I have taken the embodiment of Figures 7-8 as a typical one in which to show this entire reliance.4

embodiment, nor oi' the other or broader reliance to a grand-piano or axially-movable-hammer embodiment, or the like, for various features of the embodiments will obviously be interchangeable by those skilled in the art.

In broad analogy to earlier embodiments, the energy-absorptive material is again disposed to be deformed, or internally moved, by the hammer on its rebound from the string. Since the opposing-impact principle is not being relied on, however, the material is not carried by the hammer in the special manner permitting its independent movement. Indeed, it may if desired not be carried by the hammer at all, but rather by the keyand the latter disposition I have chosen for showing in Figures 7-8. Most conveniently in such a case the material will be held in some form of retaining means, which with the material itself is conveniently designated as an energy-absorbing device. It will be understood, however. that the retaining means must leave the material e'ectively exposed to the energy of the hammer so that it will be deformed thereby.

In Figures 7-8 I have illustrated a respective and thus, broadly, the retaining means, is accordingly characterized by a slight resiliency. This resiliency is sufficient to insure the repeated return of the material and device to a predetermined normal or dormant condition, but is small enough sorthat the predominant reaction of the device remains a viscous or resistive reaction.

While the material may be broadly any such eHectively fluid, viscous material as has been typically suggested above (fluid, semi-fluid or agglomerate) I have preferred in this construction to employ a semi-fluid such as or very similar to gum in the abovementloned form. While that itself has proven quite satisfactory, it is plobably somewhat less impervious to ultimate change than for example the synthetic resinsand to the latter I may point for a material which I have found especially desirable. A

' specific example of a synthetic resin which I energy-absorbing device lill carried by the key 1 III (specifically by its rearwardly extending bar |31) underneath the adjustable hammer screw I above described. The retaining means of the device |50 may conveniently include an upright cup Il! inset into the top of the bar |31. The cup |52 is filled with a mass III oi' the material. The cup is centralized underneath the screw |48 so that the latter tends to be pushed against by the material upon keydepression (i. e., rise of |31 and |50). To prevent undue penetration of the material by the screw |49, sticking of the screw in the material, and for other reasons apparent immediately below, the material Il may in this construction be covered by a very thin membrane |53 of soft rubber, which may be ccnsideri as completing the retaining means. The membrane |53,

have employed to great advantage is that furnished by Bakelite Corporation under the designation of "Synthetic Resin 621-193B.

This material has roughly the appearance of live rubber and, at room temperature, approximately the consistency of a candy gum dropY (from which the ordinary outer surface has been removed). It is non-hydroscopic. It has elasticity, in that upon the removal of a deforming force it tends to restore to its prior configuration; but this restoration is very slow compared.

to that of rubber. It will extremely gradually respond to a sustained deforming force: thus to the force of gravity a solid sphere of this material will respond by flowing to a fiat surface in a container in the source of about a month at room temperature. Its variation of characteristics with temperature is such that if heated to about 350 degrees F. it will ow with about the consistency of cool molasses: the riormal characteristics abovementioned will be restored upon cooling back to room temperature. Heating to appreciably more than 350 degrees F., however, causes a fundamental change in thermaterial, such that it will not thereafter recover its normal characteristics.

I may mention a method of constructing the devices ISI which I have found very convenient and satisfactory. A suilicient mass of the absorptlve material, of irregular shape, has been placed in the upright cup |52, and a hot iron has been applied to soften the material so that it flows to a full level in the cup, forms a thin film on the top rim of the cup, and disposes of its excess. The cup has then been promptly inverted and pressed downy against a sheet of the membrane rubber. Upon cooling the membrane rubber has been trimmed away from the periphery of the cup rim, leaving the membrane I 53A secured in place by the material itself.

While I have disclosed the preferred membrane |53 as of rubber, I have pointed out that it should be very thin in order to limit the resilience which it introduces into the device. Since only limited resilience or restorative tendency is wanted, it is possible quite satisfactorily to employ other Inaterial inherently less resilient, such for example as silk or other cloth-particularly when the material lil is itself characterized by a restorative tendency, as is the synthetic resin abovementioned.

As key depression is begun the membrane |53 of the device |50 will almostrat once be brought up into contact with the bottom of the hammer screw itl. The diameter of screwis appreciably less thanthe internal cup diameter, so

that there is an opportunity for the mass Ill of absorptive material to be deformed, by reduction in height immediately below the screw and increase in height therearound; at this time, however, the tendency toward this deformation is only slight, since the mass and inertia of the hammer are small. As key depression is continued the hammer, its screw I now driven through the device |50, will be propelled toward the string. Very slightly before lthe hammer head reaches contact with the string, the key movement is stopped by impingement of bar |81 on the up-stop formed by the Ielt strip |62; the hammer may then be said to be tripped, or freed from operative connection with the key. It will continue its movement for the short distance required for striking, and will then rebound through the same short distance, bringing the bottom of the screw |49 into impingement against the now-raised device |50. This impingement, occurring with a velocity dependent on original key velocity, will cause a corresponding degree of deformation of the material IBI. The work done in this deformation absorbs a large part of the energy of the rebounding hammer; the further work done in the substantial recovery from that deformation, urged by the limited reslliencies of the material ISI and of the membrane |53, absorbs a further large part of that energy, and renders the recovery so slow as to impart only the feeblest of bouncing motion to the hammer. insumcient to carry it back to the string.

While the initial deformation of the material I5I, attendant on the beginning of key depression, has been noted to be only slight. it nevertheless may be suillcient to provide a beneficial automatic eirect. This deformation will comprise a slight reduction of height of the central portion of the device |50 underneath the screw |49; and this slight reduction will be the greater. the greater the key velocity. During the minute interval between hammer tripping and the completion of rebound, there will of course be essentially no restoration of this reduced height to normal. Accordingly, the greater the key velocity and thus the greater the kinetic energy of the hammer, the greater is the distance through whlchit rebounds from the string and thus the greater is the distance through which a bounce would have to extend in order to cause the unwanted second striking. On the other hand with low key velocities, when the minimum tripping (and rebound) distance is desirable, substantially no reduction ofheight or increase of distance occurs.

It will of course be understood that with this embodiment repetition is just as perfectly available as inlthe earlier embodiment. And, though not necessary. there may if desired be employed as an additional refinement the collapsible' spring system ll-ll illustrated and described in connection with the earlier embodiment.

Suitable string dampers, or vibration-terminators, may readily be provided in the embodiment of Figure 5. The damper for each string maybe a respective felt pad ill, held atthe top ol' a respective substantially vertical arm |12 disposed in a transverse plane behind the strings. The ann |12 may be formed of dat. light metal strip; and it will preferably be provided with iianges l 12o folded forwardly from the side edges of its top portion, to embrace the rear portions of the sides ioi' the pad III.A The bottom of the arm |12 may be a point of pivoting for the am.

a suitable pivoting arrangement being described below; and at this point the material of the arm may be bent to extend forwardly, passing closely alongside the respective string through the plane of the strings. in the form of an arm |13. The arm |13 may extend to have its forward extremity normally slightly spaced above a rearward lug or projections I 31a formed from the lower rear portion of the respective bar Ill; and the forward portion oi' the arm |13 may be sumciently weighted. as by weight Illa, to impart to the arms |13 and |12 a bias (clockwise as illustrated) urging the damping pad ill against the respective string. Upon key depression, however, the lug Illa will be brought upwardly into impingement against the bottom of arm |13, and will rock arms lll and |12 (counterclockwise as illustrated) to carry the damping pad lli rearwardly out oi' contact with the string.

For supporting the dampers a transverse damper rail may be provided in the form of wooden or other members |18 secured transversely oi' the instrument between the successive T-beams Iithe front surface of the rail may be advantageously inclined upwardly and rearwardly. The pivoting of each damper arm system III-HI to the rail may be carried out by a respective suitable cloth strip ill folded back on itself at the point of juncture of the two arms, one fold of the strip extending upwardly along and being secured to the back oi' arm |12. and the other fold of the strip extending upwardly along and being secured to the inclined front surface of the rail Ill. A stop for possible overshooting movements ofthe dempers may be provided in the form of felt or like strip III secured along the top portion of the front surface of the rail.

To remove all the dampers at once from contact with the respective strings, there may be provided underneath the forward extremities of arms Il! a transverse rail ill; this may for example he held at the forward extremities of suitable arms lll, whose rear extremities are pivoted to pivots such as lll to establish a generally vertical, short arcuate path of movement for the rail llt. A pedal such as IIS. acting through rod III, may upon depression lift the rail I and so move all the dempers rearwardly.

Itistobeunderstoodthatwhileinllgures 'l-B I have shown an energy absorbing device of one particular construction, a great number of alternative constructions are available. Two auch constructions have been illustrated by the respective bumpers Il and Il in Figure 6. 'Ih'ese are of course not limited. in their utility with a hammer, to association with the auxiliary or secondary mass (rod) li-there being obvious their equivalence in operation to the devices lll, as well as the availability for them of materials similartothe mass Ill and membrane ill ofthe latter devices.

Another typical construction I have illustrated inPlgureS-bywlyofexamplaineonnection with a cylindrical. axially moved hammer such as In this construction there is secured in the open bottom of th'e hammer Il (for example. belowatransversediscllsecuredwlthinthe hammer a little. way from the bottom) a light ooilspringllwhichextendsforadistanoedownwardly from the hammer proper. within and around thissprlngisagenerally cylindricalmass Il of semi-duid absorptive material, such as the synthetic resin abovementlonedJ-in other words. the spring Il h imbedded in the mass Il. The

spring accordingly functions as a resilient retaining means for precluding permanent deformation of the material 58, but is of course weak enough' so that the reaction of the device as a whole is predominately a viscous one. The device may be completed by a very thin disc 59 of rubber, silk or the like adhering to the bottom oi the material and precluding any sticking to the capstan or screw lll. l

While not in its broader aspects limited thereto. it will be understood that the actions constructed according to my invention are particularly advantageous when, as illustrated, the mass of the hammer is a small part of the total mass moved by the key. Then there is automatically insured t'he absence of any feeling by the players lingers of the rebound of the hammer. The small-mass hammer is otherwise desirable when the vibrators to be excited are relatively small and light; such vibrators are the preferred ones in instruments operating by mechanica-electro-acoustic translation (such as the illustrated electronic pianos), and for these instruments my invention thus has an especial utility.

While I have shown and described my invention in terms of particular embodiments thereof, it will be understood that the details of these embodiments may be varied within wide limits without departure from the true spirit or proper scope oi' the invention. That scope I undertake to express in the appended claims.

I claim:

1. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator; and means, carried by and movable relatively to the hammer, for suppressing bouncing of the hammer from said stop means back to the vibrator.

2. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator; and means, comprising a mass moved by and relatively to the hammer, for suppressing bouncins i' the hammer from said stop means back to the vibrator.

3. The combination according to claim 2, wherein there is comprised means for causing a viscous resistance to the movement of said mass relative to the hammer.

4. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator: stop means against which the hammer rebounds after striking the vibrator; and means, comprising an efiectively fluid mass characterized by a high effective viscosity and subjected to internal movement by the hammer, for suppressing bouncing of the hammer from said stop means back to the vibrator.

5. In a musical instrumenta, an exciting action for a vibrator comprising. in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator: and visco-elastic means characterized by a predominately viscous reaction for suppressing bouncing of the hammer from said stop means back to the vibrator.

6. In a musical instrument, a key-operatedexciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; key-moved means for impeiling the hammer toward the vibrator and acting as a stop for the rebound thereof; and means, carried by and movable relatively to the hammer, for suppressing bouncing of the hammer from said keymoved means back to the vibrator.

7. In a musical instrument, a key-operated exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; key-moved means for impelling the hammer toward the vibrator and acting as a stop for therebound thereof; and means, comprising an effectively fluid mass characterized by a high effective viscosity and subjected to internal movement by the hammer, for suppressing bouncing of the hammer from said key-moved means back to the vibrator.

8. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator; and means, loosely carried by the hammer, for effecting a bounceopposing impact on said hammer at the conclusion of hammer rebound.

9. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator; and means, loosely carried by the hammer, for effecting a rebound-opposing impact on said hammer at the beginning of hammer rebound and a bounce-opposing impact thereon at the conclusion of said rebound.

10. In a musical instrument, a vibrator-exciting action without an escapement comprising, in combination, a hammer movable to strike the vibrator and to rebound therefrom; and means, loosely carried by the hammer, for effecting an opposing impact on the hammer upon its rebound from the vibrator.

11. In a musical instrument, a vibrator-exciting action without an escapement comprising, in combination, a hammer movable to strike the vibrator; a mass carried by the hammer and subjected to movement relative thereto when the hammer strikes the vibrator; and viscous damping means associated with said mass and eti'ective upon said relative movement.

12. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; stop means against which the hammer rebounds after striking the vibrator: a mass carried by the hammer and subjected to movements relative thereto when the hammer strikes the vibrator and when the hammer strikes said stop means; and viscous damping means associated with said mass and eil'ective upon said relative movements.

13. In a musical instrument, a vibrator-exciting action without an escapement comprising, in combination, a hammer movable to strike the vibrator and to rebound therefrom; means, carried by the hammer, for effecting an opposing impact on the hammer upon its rebound; and efiectively viscous means subjected to deformation by the hammer upon its rebound for absorbing energy from the rebounding hammer.

ing action without an escapement comprising. in combination, a hammer movable to strike the vibrator and to rebound therefrom; effectively viscous means subjected to defamation by the hammer for absorbing energy from the rebounding hammer; and resilient means associated with said last-mentioned means tor restoring the same to a normal configuration.

16. In a musical instrument, a vibrator-exciting action without an escapement comprising, in combination, a hammer movable to strike the vibrator and to rebound therefrom: effectively viscous means subjected to deformation by the hammer for absorbing energy from the rebounding hammer; and resilient means within said last-mentioned means for restoring the same to a normal consuration.

17. In a musical instrument, a key-operated exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; key-moved means for impelling the hammer toward the vibrator and acting as a stop for the rebound thereof; and Visco-elastic means characterized by a predominately viscous reaction interposed between said last-mentioned means and the hammer.

18. In a musical' instrument. a vibrator-exciting action operated by a limitedly movable key comprising, in combination, a hammer moved by the key to a relatively small spacing from the vibrator and thereafter moved by its own momentum to strike the vibrator and to rebound therefrom through said spacing; and movementtransmitting means, interposed between the hammer and the key, yieldable in accordance with the velocity of key movement and characterized by slow recovery, whereby said spacing is caused to vary with the velocity of key movement.

i9. In a musical instrument having a vibratorexciting action: the combination of a depressible key included in and operating said action; and collapsible spring means rendered eil'ectlve by said key in its downstroke, for first building up and then releasing an impedance to said downstroke. 4

BENJAMIN F. MIESSNER.

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