US2594967A - Apparatus for production of music - Google Patents

Description

April 29, 1952 B. F. MlEssNER APPARATUS FOR PRODUCTION OF' MUSIC Filed Nov. 5, '1946 2 SHEETS-SHEET l .MR `J\ v Snventor E S SHE? Benjamn F. M

April 29, 1952 B. F. MlEssNx-:R 2,594,967

APPARATUS POR PRODUCTION OP Musrc Filed Nov. 5, 194e 2 SHEETS-SHEET 2 m www Mr'essner Patented Apr. 29, 1952 UNITED STATES PATENT OFFICE APPARATUS FOR PRODUCTION-OF MUSIC Application November 5, 1946,' Serial No. 707,879V

(Cl. 8kb-240) 1.7 Claims. 1

rihis invention relates to musical instruments, and more particularly to those-of the .typewherein tuned vibrators are subjected to impulse-'ex'- citation by mechanical means. The invention contemplates especially, tho-ugh not in all aspects limitatively, instruments of the piano type-,wherein tuned strings or other vvibrators are'percussively excited by hammers underthe control of 'a keyboard. The description will accordingly. be'presented largely with relation to a piano'.

This application is in party a continuation of4 my copending application Serial No. 566,979filed on December 7, 1944, on which U. S. Ratent No. 2,469,568 has since been issued.

In U. S. Patent No. 2,271,460 issued January 27, 1942, on an application of mine and' in the copending application above. referred'to, I'have disclosed vibrator-exciting actions from which there were omitted the tripping or escapement mechanism for displacing a jack, the back-check, and the repetition mechanism, of :conventional actions. In these constructions.'thesha'mmerwas' permitted to rebound from the vibrator against the same actuating means as had propelled itl toward the Vibrator (assuming continued key defpression) but unwanted rebound ofthe hammerV from the actuating meansr backtoward the vibrator was suppressed by the'appropriate application to the hammer of opposingimpacts, aidedv by the appropriate introduction' of viscous'energy dissipation into the system.

The present invention has for an object the improvement of actions of the type disclosed'in the patent and copending application above mentioned.

One disadvantage attendant in some degree onV the actions I have disclosed heretofore'has'been a tendency toward prolongation of the contact of the hammer with the vibrator. It is an object of the present invention to reduce or eliminate any such prolongation.

Another disadvantage attendant in some degree on the former actions has been va slowing of -the return of the hammer to redrivable position when the key has been promptly released--an eiect which, while stillV leaving the return.favorab1y comparable with that in conventional actions; can be reduced or eliminated. Itis lan object of the present invention to reduce or eliminate any such slowing of hammer return to redrivablel position.

It is an object to provide an action, ofzthe. simpliiied type above referred to, whose construction is extremely simple and inexpensive.

It is an object to. provide an actiomofithefsim- .plied type with which theireducti'on'iasfb'y a,

2 soft peda1) of keystroke willbe unaccompanied by any movement of the keys.

It is an object to provide an action of the simpliiied type in which the feel of the key to the player will closely simulate that of the key in aconventional action.

It is' an object to provide a simplified and improved damper` construction and control.

It is an object to provide a simplified and improved flange-hammer assembly.

It is a general object to provide a simplified and improved action.

Other and'allied objects will more fully appear from the rfollowing description and the appended claims.

In the description of my invention hereinafter set forth, reference is had to the accompanying drawings, in which:

Figure `l isan elevational'view 01E-one` embodiment` of my'invention, by way of` example illustratingj that embodiment in an upright-piano action of the so-called dropped type;

Figure 2 is a fractional elevational view'of anotherl embodiment of-my invention, by way-of example illustrating that embodiment in an "undropped type of upright action such as ismore ful-ly illustrated in Figure 3;

Figure 3 is` an elevationalview of another embodiment voi my invention, which I presently believe' to be preferable to' the. precedingy two;

Figure 3a isa fractional repetition of Figure 3, but showing-the `keyyandhammer positions at an intermediate point inthe stroke of the key;

Figure-3b is an enlargement, with a smallpart '.brokenaway, of-a portion of Figure 3;

Figurec is a cross-sectional view'taken substantially along'the line 3c-3c of Figure 3b;

Fig-ure 4 is' a `fractional elevational view of anothery embodiment of myinvention, by way of `example in-av type of action similar to that of Figure 3;

Figure 51is afractional elevational View oi an embodiment, of `my, invention; which in its `broader:aspects issimilarto that of Figure 4 but is incorporatedin agrand-piano action; and

Figure 6. is a groupof curves, plotted against time, illustrating'themotions of certain important elementsin typical embodiments of my invention.

In'Figure 1 thenumerals l, 2 and -3 respectively designate the front, intermediate and rear rails of th'etkey-assembly portion of an action. Extendingupwardly fromY the rail2 isshown a pin 4; ,encircledxby a'ibushing'or pad'5; anda key 6.

.isgshown. pivotally assembled; on`v that pin. andV resting on that pad. The front end of the key extends over the rail I, which is provided with the guide pin 'l extending upwardly and freely into the key, that pin being encircled by the bushing or pad 8 underneath the key. The rear end of the key, beginning a little behind the region of pivoting, is shown as extending diagonally downwardly-and-rearwardly, and as normally resting against a pad 9 secured on the upward-rearward surface of the rail 3'; appropriate weighting, such as indicated by 6a, may be provided in the rear portion of the k-ey. Opposite its point of normal rest against pad 9', the key is provided with an upwardly-and-rearwarclly extending capstan screw I'. The key .assembly as so described is a known one, appropriate to a dropped type of upright-piano action; and it will be understood that upon a downstroke of the front end of the key 5,', to bring it into irnpingement against the top of pad 8, the capstan f screw III will be moved a short distance upwardly-and-slightly-rearwardly, in an arc about the pivot pad 5.

Drivenby the capstan screw Iii', upon downstroke of the key (i. e., of the front end of the key), is the hammer II. This may be considered as comprising the hammer head I2; the hammer stem I3, at the top of which the head I2 is secured; the hammer butt III', in which the bottom end of the stem I3 is secured; the pad I6 covering the downward-forward surface oi' the butt I4', against which the capstan screw IU exerts its moving force; and preferably the further pad I6" inset into the butt I4' underneath the pad I6 opposite the capstan screw I6. The l butt I4', and thereby the entire hammer Il', is pivoted at I'I to a flange I 8', which in turn is secured to a suitable rail I9 in the action.

The string which the hammer II' is to strike is shown as 2U, vertically disposed behind and in the path of movement of the hammer when it pivots about II'. It will be understood that upon downstroke of the key, the attendant motion of the capstan screw I0 will rock the butt I4' rearwardly about II', carrying the hammer head I2 toward the string.

The capstan screw I0 may be so adjusted that at the conclusion of an abnormally slow key downstroke-i. e., one so slow that the pad I6 remains in contact with the capstan screw I0- the active (rear) end of the hammer head I2 will have been brought to a very small distance from the string-a distance comparable, for example, with that to which in a conventional action the hammer head has been brought at the time of "tripping (i. e., displacement of the usual jack from its normal disposition in such an action). This hammer position (of very small distance of hammer head from string) may conveniently be termed the keystroke-end position of the hammer.

The normal position of the hammer will be xed by the resting of the butt I4 (through pad IS) against the capstan screw I0', and the resting of the rear end of the key 6' (through pad 9) on the rail 3. The forward displacement of this normal position from the keystroke-end position will of course be determined by the distance through which the capstan screw I0 moves during keystrokeand this distance of capstanscrew travel is in turn established, as conventionally, by adjustments of thei effective thicknesses of pads 8 and 5 (as by choicefof the thicknesses of stacks 8a and 5a of paper or cardboard washers with which xed-thickness pads 8 and 5 may be supplemented), which adjustments of course fix the length of keystroke (as well as the normal key level).

The action. of gravity in normally causing the hammer butt I4' to rest (through pad I6') against the capstan screw It' may be supplemented, as conventionally, by the action of a light spring 2I may bear forwardly against the rearward-upward surface of the butt Id', the spring being secured at its upper extremity to a xed rail 22'.

As a stop against over-shooting of the hammer forwardly upon key release (due to momentary yieldings of various parts such as pads I6', I6 and 9', etc.), with consequent strain on the hammer stem I2, there may be provided a rail 24 carrying a strip of soft felt or the like 23 on its rea-r surface, in such a position that on forward hammer motion to slightly beyond normal hammer position the front end of the hammer head I2 will impinge against the strip 23-from which it will, however', normally have a slight spacing. If it be desired that the hammer at times have a reduced spacing from the string Z, the rail 24 may be moved rearwardlyfor which purpose it tions of less-than-normal hammer-to-string spacing, the capstan screw I will, when the rail' 24 has been moved rearwardly, be left out of driving contact with the butt I4' until some initial portion of the keystroke has been completed.

Simply by way of simplification of illustration, there has been omitted from Figure 1 any showing of the usual damper for the string 20; this may, however, be provided in any convenient manner (for example, as I have shown for a similar dropped type of Iaction in my co-pending application Serial No. 566,979).

The key 6', with capstan screw I0, will be understood to form an actuating means for the hammer. Thus when the key 6 is subjected to downstroke the capstan screw will drive the hammer II toits keystroke-end position. At this point the movement of the actuating means (iV-IW) will be stopped; the hammer is free, however, to continue rearward movement under its own rearward inertia (which it will have acquired during, and in amount dependent on the velocity of, the keystroke, unless the latter has been of Ialtogether abnormally low velocity). The hammer which (i) up to this point of keystroke-end had been driven by the actuating means, now (ii) does continue its rearward movement, as it is free to do, for a minute interval which ends with its striking of the string; then (iii) produces an initial rearward deflection of the string, and during that rearward denection maintains its contact with the string and thus progresses, though at reducing velocity, rearwardly beyond the strings normal position; then (iv) returns forwardly, still in contact with the string, as the string accelerates forwardly from its maximum deflection to its normal position; then (v) continues its forward movement under its own forward inertia (becoming free of the string as the string, passing its normal position, decelerates in its forward movement) for the minute interval required to bring it into its keystroke-end position.

The further behaviour of the hammerdepends on the history of the key, or actuating'means,

The lower end of this spring during the intervals (ii), (iii), above, and is dealt with below.

The motions of the hammerv so describedl are shown diagrammatically in Figure 6, by the solid curve from its lefthand extremity to the point designated In this figure time is measured alongthe horizontal axis, and displacement along the vertical axis. The horizontal axisO-O itself designates the normal position, the horizontal line KE-KEdesignates the keystroke-end position, and the horizontal line SS-SS designates the string-striking position, of the hammer; The several, intervals (i), (ii), (iii), (iv) and (o) above areY laid off by vertical lines at the top of thefigure, andare designated by their respective numerals. The letter AV designates` the beginning, and the letter B the end, of interval (ii).

If during the intervalsl (ii) (iii), (iv.) and (o) thev key has been released, the` hammer. onr arriving upon the conclusion of: (v)v at its keystroke-end position (i. e., at the pointE in Figure 6);, will simply continue its forwardmovementw ata slightly increasing velocity caused by gravity and by the spring 2|. This return of thehammer to normal position has been indicated in Figure 6 by the dash-dot line E-G. Of course, if the key has been only partially released, the hammers return will not extend all thev way to its normal position (e. g., G), but will stop at some intermediate point (e. g., F) determined by the degree of key release. But whether the key has been fully or only partially released, there is nevertheless maintained the maximum possible speed of return of the hammer into a position where it can be eifectively redriven by the key-a characteristicI described in piano terms as excellent repetition.

If, however, the key has not been released by the end of interval (o) the hammer will at that instant come into irnpingement against the actuating means (i. e., against IU in the system -if), The hammer then (ui) will by its inertia cause a temporary compression of various compliances in the system, including the hammer (iv) and (v) stem i3 (since the hammers inertia is principally l in the head I2, whose motion the curve illustrates), the pads I6 andi I6, the pad 5, the pad 3 (in this case, a temporary de-compression) and various other compliances, the hammer moving forwardly at reducing velocity while yielding up its energy to those compliances; then (vii) will be moved rearwardly, by the release of the energy acquired by those compliances during interval (ci), at a velocity which increases until the hammer again reaches keystroke-end position, by which time all the energy it delivered to the compliances (reduced only byl dissipation therein) will have reappeared in the hammer in the-form of rearward inertia.

The solid curve of hammer motion in Figure 6 has been extended from E' to H to indicate the motions occurringduringtheseintervals (Ui) and (vii), which have been laid off similarly to earlier intervals.

If no counteractive measures are4 applied, the hammer at the end of theinterval (uit) will respond to its own rearward inertia by entering (at H) an interval (viii) which will be a repetition and rerepetition of the cycle (iz)--(z'ii)- (iv)-(v)-(vz')-(oii) which began at A; this repetition and rerepetition willy continue as an oscillation of the hammer until theamplitude of motion, which decreases with each cycle as a result of such dissipations as there are inthe system, has died-away.l The dash-dot extension of the curve from H to J indicates a typical firstv cycle-and-a-quarter of the interval (viii); there will` be apparent itssimilarity to the courseof the curve beginning at A, excepting only for the attenuation of amplitude.

The amplitude of the hammer oscillation just describedis of course a function of the amplitude of the initial-string,displacement by the hammer, and thus` of the velocity of the actuating' keystroke. But if the keystroke-end position of the hammer is made properly close to the stringstriking position (which should be done for good sensitivity of thev action), then with all excepting very weak keystrokes the amplitude of hammer oscillationA is usually` sufiicient to-cause the hammer to restrike the string at least once, if not oftener. Thus if the curve in Figure 6, which represents a fairly strong, keystroke, werey extended in its oscillatory form beyond J,v then even in spite ofv a logarithmically decaying amplitude it would show, following the intended initial one, several repetitive crests reaching above or at least to the line SS-SS. Each such crest wouldv represent a restriking of the string by the hammer even if the string were remaining in its normal position indicatedby that line. Of course actually, following the initial contact of the hammer with the string (represented by the first crest), the string is in a state of vibration, or rapid oscillation between points displaced in each direction from the normal position indicated by SS-SS. rihis factwouldhave-some infiuence on the exact course of the. curve in the dash-dotV portion to the right of, H--but since largely fortuitous phase and other relationships are involved, it is necessary in extending the curve to assume some average or typical relationships. More importantly, thisfact of string oscillation decreases the distancev beyond the keystroke-end position (i. e., aboveline KE-KE) through whichV the hammercanx travel without danger of restriking the string, and thus increases the probable number of restrikings over the number that would be expectable with a string which occupied the fixed normal position except while actually being displaced by the hammer.

Conventional kpiano actions have circumvented this hammer oscillation byan escapement mechanism which in eiect removes the actuating means from the path of the hammer rebounding` from the string-and following strong keystrokes have absorbed the very considerable kinetic energy of the hammer at a considerable distance from the string by dissipation in a frictional engagement of the hammer with a back-check. This has been done, however, at thecost of elaborate, delicate and non-altogether perfect arrangements for preserving acceptable repetition, as well as of the escapement mechanism and back-check themselves.

In my U. S. Fatent No. 2,271,460 I showed an action in which the actuating means might be rebounded from by the hammer, but in which such rebound was suppressed (a) by applying to the hammer, during interval (iv) or (u) as described herein, a stringward impact opposing and greatly attenuating the hammer rebound from string to actuating means, (b) by applying to the hammer, during or immediately after the interval (uit) as described herein, a reverse impact opposing the-residual tendency of the hammer to rebound from the actuating means, and (c) by appropriately introducing viscous energy dissipation into the system. While embodiments of that disclosure Aperform their functions of avoiding rebound of the hammer from the actuating means, they have exhibited certain disadvantages, among them being a tendency, at least under conditions of slight maladjustment, of the first of the impacts applied to the hammer to prolong the contact of hammer with string, and a considerable undoing by the same impact of the otherwise inherently rapid return of the hammer to redrivable position when the key has been quickly released.

In my cci-pending application Serial No. 566,979 I disclosed an action in which I reduced the magnitude ci these disadvantages by applying the first impact to the hammer through a spring, thus attenuating the effect of that impact and storing much of the energy thereof for delivery to the second impact on the hammerwhich second impact was delivered to the hammer at the time denoted by the point H of Figure 6 herein.

According to the present invention I continue to deliver to the hammer at the time denoted by the point H (of course, assuming that key depression is maintained) an impact opposing the movement of the hammer toward the string. But I so support the inertia means which delivers the impact that it is incapable of delivering to the hammer any impact in the reverse direction, this being achieved for example by using an energy-storing spring as the support for the inertia means. In such a construction the inertia means is effective at least as soon as the stringstriking to deliver energy to the spring-and the spring is deflected at least throughout (i. e., during the entirety of the inertia-effected movement of the inertia means.

In Figure 1 the. spring, of leaf construction, appears as 21, with its lower extremity secured in the hammer butt I4' slightly forwardly of the stem I3. From the butt the spring 2'I extends diagonally upwardlyk and forwardly, diverging from the stem I3. On its forward surface at its upper extremity the spring carries the weight 28, which (supplemented to a relatively minute extent by the mass of the upper portion of the spring) forms the mass or inertia means of the system.

Secured in the hammer II', for example at the juncture of the head I2 with the stem I3, may be the rear extremity of a light arm 29, which may extend generally forwardly, at about right 5 angles to the stem I3, to terminate in a portion 29a folded downwardly at right angles to the rest of the arm 29. To the rear surface of the arm portion 29a there may be secured a pad 3c, preferably characterized by elasticity accompanied by appreciable viscosity. For the pad 3e there may be employed a suitably shaped lump of viscous material such as a synthetic resin; in this case the imperfect elasticity, and the tendencies to cold-flow, of such material may be counteracted, and the pad made fully elastic, by encasing that material in a lm or skin of rubber (surface-dusted with graphite to obviate any stickiness). More simply and usually satisfactorily, however, a pad.30 of relatively viscous rubber such as "butyl may be employed.

rIlhe length and biasing of spring 21 are such that the weight 28 normally rests in contacttypically, relatively light contact-against the pad Sii. During keystroke, or interval (i) the entire hammer including 29-30, and with it the spring-weight system 2'I-2 8, is moved integrally, and such movement continues during interval (ii) as well. But upon the striking of the string by the hammer at the end of interval (ii) whereupon the hammer begins its rapid deceleration already seen to occur in interval (iii) the rearward movement of the weight 28 is continued under the influence of its own inertia-as illustrated by the heavy dotted line, to the right of A, in Figure 6. Accordingly the weight 28 upon the string-striking leaves contact with the pad 3B, and begins the delivery of energy to the spring-i. e., begins the deflection of the spring. This delivery and deflection continues at a diminishing rate for a space of time which is a function of the time-period of the mechanical oscillating system formed by the spring and weight-and which is followed by another space of time, similarly a function of that time-period,

of redelivery of the energy of the spring to the weight and deflection of the springf These two spaces of time, taken together, represent an interval of free excursion of the me'- chanical oscillating system in its own oscillatory mode, beginning at the instant of string-striking by the hammer. The time-period of that system is so xed, by choice of the relative values of the stiffness of spring 2l and mass of weight 28, that this interval of free excursion is substantially equalized with the sum of the interval (iiD-(iv) of hammer contact with string, the interval (o) of hammer travel from string to actuating means, n

and the interval (oh-(vii) of hammer contact with actuating means prior to an attempted rebound therefrom. The time-period of the system being so Fixed, it is at the end of interval (vii)- or at the time denoted by H in Fig. -that the weight will be returned to contact with the pad 3D.

This return to contactwill of course be an impactive one-constituting an impact of the weight against the hammer opposing the attempted rebound of the latter toward the string. Its objective is to neutralize, by the away-from-the-string kinetic energy of the weight, the toward-thestring kinetic energy of the hammer. This neutralization is readily accomplished by a proper choice of the absolute values of stiffness of spring 2l and mass of weight 28 (the relative values of which are, as seen above, to be so fixed as to achieve the proper time-period).

The heavy straight-line curve to the right of the point II in Figure 6 illustrates the continued positions (throughout continued key depression) of hammer and weight after the weight-hammer impact, when the parameters of the mechanical oscillating system have been properly chosen. It will of course be apparent that the hammer is held in keystroke-end position, wherein it is harmlessly out of contact with the string, even in spite of the vibration of the latter. It may be pointed out that an appreciable viscosity of the pad 38, abovementioned as desirable, provides considerable tolerance to imperfect choices of parameters of the spring-weight system. When such viscosity is present, then although the curve to the right of point I-I may be slightly oscillatory as a result of the imperfect choices, nevertheless the energy dissipation caused by the viscosity will (unless the imperfections are relatively gross) limit the amplitude of the oscillations sharply enough to accomplish the objective of obviating any second contact of hammer with string.

The appropriate introduction of a viscous damping of the impact of weight against hammer may be accomplished in other manners than by the use of a pad, such as 30, through which the impact is transmitted compressively. Thus in Figure 2 I have illustrated an embodiment of my invention wherein the viscous damping is provided by a flexible member characterized by appreciable viscosity, and wherein that impact is transmitted through that member in tension.

Purely by way of example that embodiment is illustrated in an upright action of the undropped type (such as is more fully illustrated in the succeeding Figure 3). Herein the rear end of a straight key is illustrated as 6, provided for example with a weight 6a similar to that of Figure l. Secured to the bottom of the rear portion of key 6 is a rigid extension plate 6b, which extends a short distance rearwardly from the rear end of the key proper and, through pad 9, rests on the rear action rail 3 when the front end of the key is not depressed. On top of the extending portion of plate 6b there may be secured the pad I6. The hammer II again comprises a head I2 and a stem I3, the lower end of the stern being secured in a butt I4 of somewhat different construction from the butt I4 of Figure 1. The butt Ill is provided with a forwardly extending shoe Ma through which, at a little distance forwardly of the stem I3, there passes the adjusting screw I0. The top of this screw may be provided with a screw-driver slot ma for adjusting purposes, while the bottom of the screw may be formed into a round head I Ilb.

The butt I4, and therethrough the hammer I I, is pivoted at Il to a rearwardly extending flange I8, which may be secured to the top of a rail 22 which in turn is secured to the top of the rear action rail 3i?. A spring 2 I, one extremity of which appears in Figure 2 (but which is illustrated more in detail in subsequent figures) may lightly urge the hammer forwardly about pivot Il. The forwar-d-and-rearward position of the parts is such as to bring the screw-head IUb above the pad IE, against which it normally rests.

It will of course be understood that in Figure 2 the movement of the hammer by the key 6 is functionally entirely similar to that of the hammer II by the key 6 in Figure 1, the screw I0 performing the same function as the capstan I0 in Figure l. As in Figure l, the rail 24 (forming, if desired, a portion of a bail one of whose side-arms appears as 25, pivoted at 26), provided with the strip 23, may form a stop for excessive rearward excursions of the hammer (as well as a means for reducing its stroke at will) In Figure 2 the mechanical oscillating system is shown as formed by the spring 37 and the weight 38. The lower end of the spring is shown secured, as by the small screw 36, to the top of the butt-shoe Illa; and therefrom the spring extends upwardly and forwardly in generally similar fashion to the spring 21 of Figure l. The weight 33 is carried at the top of the spring 3lsecured for example to the rearward surface of the spring. The weight (and the spring in contact therewith) may be apertured, and there through there may be passed a thin strip 39 of viscous material having self-restoring properties and not significantly subject to coldiiow-for example, Vinylite This may be formed, immediately in front of spring 31, into a knot 33a incapable of passing through the spring and weight. From the spring and weight the strip 39 may extend rearwardly to the hammer head l2, its rear extremity being secured therein.

The spring 37 is so biased that it normall;7 places the strip 39 under at least slight tension. Upon depression of the forward end of thel key 6, and consequent raising of the illustrated rear end of the key, there will occur an integral movement of the hammer I I and mechanical oscillating system 31-38 toward the string 2i). Upon string-striking by the hammer there will occur a free excursion of the oscillating system 37-32 similar to that of 2'1-23 of Figure l-excepting that it will be accompanied by a release of the tension of strip 39 and, consequently, an inert folding of that strip.

The free excursion of the system 2li-38 in its own oscillatory mode involves, quite similarly to that of the system 21-28 of Figure l, first a rearward deilection of the spring and then a forward deilection thereof-culminating in a forwardly directed impact of the weight on the hammer. In this instance, however, the forward impact is delivered longitudinally through the strip 15S- this having been unfolded by the deliection of the spring, and being placed in ten-- sion by the impact.

'Ihe solidly shown curve in Figure 6 is equally applicable to the hammer movement in the embodiment of Figure 2. It is to be observed, however, that the viscous damping means in tension (i. e., strip 39 of Figure 2) has proven generally even more effective than the corresponding means shown in Figure 1 in providing tolerance to inexact choices of the parameters cf the mechanical oscillating system.

In Figure 6 the solidly shown curve from O tc B, the dottedly shown curve from B to H, and the solidly shown curve to the right of H show the relative positions of the weight 28 of Figure 1, or 38 of Figure 2. For the construction of either gure the period from O to A, or interval (i), is one during which the actuating means drives the weight, or energizes the mechanical oscillating system; the period from A to B, or interval (ii), is one during which the weight travels on in contact with a portion (3D or 39a) of the hammer, the oscillating system remaining energized; and the period from B to H is one during which the weight moves rst under its own inertia and then under the restoring force of the spring, the oscillating system executing a free excursion in its own oscillatory mode. It will be appreciated that, since the movement of the weight throughout the energization period O to A does not deiiect the spring in the constructions of these figures, the energization of the oscillating system in either case is wholly a kinetic energization.

All the folding and unfolding of the strip 39 during the weight excursion is attended by some energy dissipation, which probably becomes especially marked as the strip straightens in the momentary period just before impact. A beneficial effect of this is the elimination of even minor clicks or slapping noises, such as otherwise may tend to occur with a weight arranged (as in Figures l and 2) to move with approximately the velocity of the hammer head.

In Figures 3, 4 and 5 I show respective embodiments of my invention in which the mechanica-l oscillating systems are carried elsewhere than by the hammer, but intercept the path of movement of a portion of the hammer. In these embodiments the inertia means deilects the spring, and thus the oscillating system is subjected to internal movement in its own oscillatory mode, during the terminal part of interval (i) the interval of hammer-actuating movement of the key.

In Figure 3 the rear end of the key 6 is provided, as in Figure 2, with the extending plate 6b secured to the bottom of the key; and again this extension plate 6b may carry the pad I6, and may normally rest through the pad 9 on the rear action rail 3. Again the hammer butt I4, pivoted at I1 to the flange I8 secured to rail 22, may be provided with the forwardly extending shoe I4a, through which passes the adjusting screw ID 'whose head I0b normally rests on pad I6. The hammer II again includes the stem I3 extending from the butt I4, and the head I2 carried at the top of the stem I3.

In this embodiment the mechanical oscillating system is carried by the key. It comprises the leaf spring 41 secured to the top of the key (as by screw 41a) and extending rearwardly to overhang the end of the key; and the weight 48 secured to the bottom of the overhanging por- .tion of the spring.r Behind the screw 41a the key 6 may be slightly reduced in height, so as to provide under the central portion of the spring 41a a surface 6c slightly lower than the bottom of the spring under screw 41a; and on the surface 6c there may be secured a pad SU-the spring 41 being so biased as to normally bear at least lightly against the pad 50.

The front-and-back position of the rear extremity of the spring and weight 41-48 is just a little forward of the adjusting screw l0, permitting access to the latter. The butt-shoe I4a, however, extends forwardly beyond that screw so as to bring the most forward portion of the shoe underneath the weight 48. To the top of this portion is secured a pad 49. Preferably both the pad 49 and the pad 59, abovementioned, will be of elastic material characterized by appreciable viscosity-butyl rubber, for example. The height of pad 49 is typically made somewhat less than suiiicient to reach the bottom of weight 48 when the parts are at rest.

Upon key depression the screw I and with it the butt I4 will be rocked upwardly, and the hammer head I2 rearwardly, about the pivot I1. The pad 49, moving in an arc of greater radius than the screw I0, will presently be brought into contact with the bottom of the weight 48. Figure 3a illustrates a typical position of the parts when this has first occurred; the key may then, for example, have been moved through somewhat over half of its downstroke. Up to this time the weight 48 has been moved simply with the rear end of the key, and the spring 41 has notbeen deflected. During the remainder of key depression, however, the weight 48 is moved by the pad 49; in view of the step-up of motion in the butt-shoe I4a, this movement is at a greater rate than that of the key-end, and accordingly the spring 41 is subjected to a progressive upward deflection.

In Figure 6 the dottedly shown curve from O to Q and the solidly shown curve from Q to A indicate the relative positions of the weight 48 during the keystroke-it being understood, of course, that the motions of the weight as indicated in Figure 6 have been multiplied several times from their actual values, in order to permit the convenient use of the single figure for different embodiments. The solidly shown curve of Figure 6 of course continues to represent the hammer movement.

After the conclusion of keystroke at A the weight 48 continues to move under its own momentum, and continues to progressively flex the spring 41; since the key movement has stopped at A, the rate of spring nexure abruptly increases at A. During interval (ii), or from A to B, the pad 49 (which forms a part of the hammer) maintains contact with the weight 48,v and the momentum of the hammer combines with that of the weight in iiexing the spring. As in the cases of earlier embodiments, it is upon string-striking-i., e., at B-that the free excursion of the oscillating system in its own mode, represented by the dotted curve from B to H, begins; a distinction from those cases is that in this case the spring 41 had already been considerably lflexed by the weight 48 prior to the stringn striking.

It has already been noted that the actual movement of the weight 48 is only a fraction of that of weight 28 or 38 in earlier figures, and of course that same is true with respect to its velocity. The requirement for kinetic energy in the weight just before the weight-hammer impact-at H remains, however, unchanged; it must equal the oppositely directed kinetic energy of the hammer'. This is accomplished with the g smaller lvelocity by a larger weight-the weight requiring. to be increased, in general, by the square of the factor by which the velocity has been reduced. The timing requirements for the free excursion of the oscillating system remain as before; the greater weight will accordingly be accompanied by a stiffer spring.

I consider the arrangement of the pad 49 so that it does not contact the weight 48 until key depression is partly effected to be advantageous in keeping at a reasonable value the iiexure of the spring 41 already effected at the time of string-striking. This feature, however, has certain additional specific advantages. One of these has to do with the use of the rail 24 to shorten the hammer stroke on occasion. Upon swinging of this rail to shorten that stroke, then if the pad 49 were normally to touch the weight, the rearward swinging of the hammer would be accompanied by a partial depression of the key. Such a partial depression is not normally an incident of soft-pedal operation, and would be objectionable; it is obviated by the spacing under discussion.

Another advantage has to do with the feel of the key to the player. In conventional actions there occurs, late in the downstroke of the key, a noticeable and quite sudden increase of key resistance to that downstroke-caused by the greater work required to displace the jack than for the hammer propulsion prior to that displacement. In the embodiment of Figure 3 Such an increase of resistance (though of course notthe result of displacement of any jack) ocours-caused by the addition of the springflexing load to the hammer-moving load already being borne by the key-at the instant in the stroke illustrated by Figure 3a. Naturalness of feel, for such value as it has to sensitive players, isthus preserved.

It may be pointed out that the much-reduced velocity of the weight in the Figure 3 embodiment (as well as in those yet to be described) eects an ample minimization of clicks or slapping noises in the action.

'Also as to the Figure 3 and later embodiments, the carrying of the mechanical oscillating system elsewhere than on the hammer fully eliminates all tendencies toward prolongation of hammer contact with string. (These, it was pointed out above, are reduced in the AFigures 1 and 2 embodiments by the elimination of any stringwarcl impact.) This is because in these later embodi- Figure 6 are several times multiplied from their actual values (relative to hammer motions). Actually, with the proportions shown in Figure 4 relative to those shown in Figure 3, the motions and velocities of the weight will be somewhat less-and it is for this reason that the weight 58 has been illustrated as somewhat larger than the weight 48 of Figure 3, which will be found necessary in following with this embodiment the criteria set forth above with respecet to proportioning of weight and spring.

This embodiment will be recognized to retain the features, of the Figure 3 embodiment, both of permitting normal soft-pedal action (through rail 2d) without unwanted key displacement, and of providing a sudden increase of resistance to key depression at an intermediate point in keystroke. (The first of these features of course inherently characterizes this embodiment, whether or not the 'finite spacing normally exists between the weight and the hammer portion which moves it; such a spacingr was, however, required in the Figure 3 construction to achieve this feature.)

It is to be understood that none of the embodiments of my invention is limited to use with an upright action. While this should be obvious to those skilled in the art, it has been illustratedhy way of example, in connection withthe embodiment of Figure Li-in Figure 5. Herein the rear portion of a pivoted key appears as E". Suitably spaced above it is the horizontal string 2li of a grand type of piano. Arranged to strike the string from underneath is a hammer II", comprising the head I2 and the stem I3 at the rear extremity of which that head is carried. The forward portion of the stem I3" is rectangularly formed, and its forward extremity is pivoted as at I'I to the flange Iii secured on top of a suitable action rail 9i. On and extending downwardly from the bottom of the forward portion of the stem I3" a little to the rear of pivot I Z there is secured the small pin S3, surrounded by the pad 92 in contact with the stem I3, and projecting downwardly beyond that pad. Below the pin 93 there extends upwardly from the key 5 the capstan screw Ill, adjustable in height relative to the key; and from the center of that capstan screw-there may in turn extend upwardly the small pin 9d. A coupling from key to hammer may be provided by a cylinder 91 provided at its top and bottom extremities with the end-closing bushings 95 and Qt respectively, those bushings being centrally apertured to freely admit the pins S3 and S1! respectively.

It will be understood that the normal position of the hammer may be fixed by adjustment of the capstan screw IG", the keystroke-end position being determined by the distance through which the capstan screw moves during keystroke (which distance is subject to adjustment in the usual manner all in analogy to the constructions set forth in connection with tFigure l. And for a stop against overshooting of the hammer downwardly upon key release, the key 6" may be extended rearwardly and may have secured to its surface underneath the bottom end of the hammer head l2 a pad I6 of suitable thickness.

The extremities of pins 93 and Sd'within the cylinder 'i' are free to assume various angles to the axis of the cylinder without binding, as a result of the cylinder diameter being substantially larger than that of the pins. The length of each pin may be great enough to preclude detachment of the cylinder from the action while the latter remains in assembled condition and in place under a normally positioned string.

In this embodiment the mechanical oscillating system may comprise a leaf spring S1 having its forward end secured (for example, by the same screw Ilia. as secures the flange |53V to the rail 9|) to the top of the flange i3, and extending rearwardly therefrom to overhang a portion of the hammer stem I3"; a rod t6 secured in a rearward portion of the spring 61 and hanging downwardly therefrom through an oversize aperture i3d in the hammer stem I3 (and preferably arcuately shaped, so as to limit the size of aperture Ia required for obviation of binding in that aperture upon hammer movement) a weight 53 secured on the bottom of the rod El a little below the downmost position of the hammer stem l3"; and a pad S9 secured to the bottom of spring 61 surrounding rod 66.

The dimensioning and disposition of the parts will of course be such that the hammer stem I3" strikes the pad S9 at an intermediate point in keystroke, entirely analogously to the striking of pad 5S by stem I3 in Figure Ll--excepting that, purely by way of example of variation, the dashdot illustration in Figure 4 of the position at which this striking will occur has been made to show a hammer movement of a little over (rather than under) half-way from normal position toward the string.

The correspondence of function to that of the embodiment of Figure 4 will be apparent, and need not be detailedly developed.

lln all the embodiments of my invention the choices of mass and stiness of the weight and spring in the mechanical oscillating system will be made according to principles already stated. It is of course to be understood that these parameters may require variation between the several notes of the instrument. This results from the criterion that the interval of free excursion of the mechanical oscillating system shall equal the sum of intervals (iii), (iv), (v), (vi) and (vii)- and the facts (l) that the lengths of intervals (iii) and (iv) are influenced by the mass of the hammer and the mass and stiffness of the string, (2) that the lengths of intervals (vi) and (vii) are inuenced by the mass of the hammer and the stiffness of various compliant portions of the action (e. g., the hammer stem, various pads, and to some extent the key itself), and (3) that at least the mass and stiffness of the string and the mass of the hammer are usually progressively varied throughout the scale of the instrument.

t has already been pointed out that the pad 3d of Figure l, the strip 39 of Figure 2, and the pads 49, 59 and S9 ofv Figures 3, 4 and 5 respectively are desirably characterized by appreciable viscosity, so that they may perform an energydissipating function upon the impact of hammer against actuating means-thereby increasing the attenuation of oscillations which may tend to occur after the weight-hammer impact, and so increasing the tolerance of the system to inexactness of choice of parameters. To a reduced extent, the same function is aided by viscosity of the several other pads immediately associated with the key and hammer in the several embodiments-and for this reason each of those other pads (e. g. in Figures 3, 5, 8, and 16) may desirably be characterized by appreciable viscosity or energy dissipation.

While I have disclosed my invention in terms of particular embodiments thereof, and with reference to a piano as a typical musical instrument and to a string as a typical vibrator, I intend thereby no unnecessary limitations. Modifications in many respects will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute departures from the spirit or scope of the invention, which I undertake to define in the following claims.

I claim:

l. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device fordelivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mass moved by said actuating means coincidentally with at least the final portion of movement of the hammer by the actuating means, and moved by its own inertiaafter the hammer strikes the vibrator; and a spring, deflected by said mass at least during said lastmentioned movement, and supporting said mass in the action.

2. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after lstriking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mass moved by said actuating means coincidentally with at least the terminal portion of movement of the hammer by the actuating means, and moved by its own inertia after the hammer strikes the vibrator; and a spring deflected by said mass at least throughout said last-mentioned movement of said mass.

3. In an action, for exciting the vibrator of a musical instrument, including `a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mass moved by the actuating means coincidentally with at least the terminal portion of movement of the hammer by the actuating means and moved by its own inertia after the hammer strikes the vibrator; and a spring` deflected by said mass at leasty during a portion of each of said two movements of said mass.

4. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mass supported for movement relative to the hammer but for the deliveri7 of impactive force from the mass to the hammer only in a direction of opposition to movement of the hammer toward the vibrator; and means for damping impactive forces delivered from the mass to the hammer.

5. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mass supported for movement relative to the hammer but for the delivery of impactive force from the mass to the hammer only in a direction of opposition to movement of the hammer toward the vibrator, and further: comprising a flexible length of material characterized by high internal damping, through which in tension such impactive force is delivered and damped.

6. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a spring, and inertia means, kinetically energized by the actuating means and effective at least as soon as the hammer strikes the vibrator to deliver energy 'to said spring for storage therein.

7. Inan action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a spring, an inertia means, kinetically energized by the actuating means and supported for movement relative to the hammer but for the delivery of impactiveforce from the mass to the hammer only in a direction of opposition to movement of the hammer toward the vibrator, for delivering energy to said spring for storage therein.

8. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising anoscillating system, formed by cooperating mass and compliance, at least partially intercepting the path of movement of a portion of the hammer,

9. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the Vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, saidv device comprising an oscillating system, formed by cooperating mass and compliance, subjected by the actuating means to internal movement simultaneously With a movement of the hammer preceding its striking of the vibrator and capable of executing a free excursion thereafter.

10. In an action, for exciting the vibrator of a musical instrument, including a vibrator striking hammer and actuating -means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising a mechanical oscillating system subjected to internal movement at least as soon as the hammer strikes the vibrator and capable of executing a free excursion thereafter, said system comprising a cooperating spring and mass jointly having a period of free excursion substantially equal to the sum of the intervals of hammer contact with vibrator, of hammer travel from vibrator to actuating means, and of hammer contact with actuating means im- 19 mediately prior to an attempted rebound therefrom.

11. The combination, with an action for exciting the Vibrator of a musical instrument and including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator, of an anti-rebound device comprising means for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said impact-delivering means extending to intercept the path of movement of a portion of the hammer.

12. The combination, with an action for exciting the vibrator of a musical instrument and including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator, of an anti-rebound device comprising means for delivering to the hammer an impact opposing ra rebound of the hammer from the actuating means, said impact-delivering means being secured to a stationary portion of said action and extending therefrom to intercept the path of movement of a portion of the hammer.

13. The combination, with an action for exciting the vibrator of a musical instrument and including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator, of an anti-rebound device comprising means for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said impact-delivering means being carried by the actuating means.

14. The combination, with an action for exciting the vibrator of a musical instrument and including a vibrator-striking hammer and actuating means therefor against which the hammer may rebound after striking the vibrator. of' an anti-rebound device comprising means for delivering to the hammer an impact opposing a rebound of the hammer from the actuating means, said impact-delivering means being carried by the actuating means and extending therefrom to intercept the path of movement of a portion of the hammer.

15. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer: the combination of a flange, means pivi oting the hammer to said flange, and a spring having a central portion coiled about said hammer-pivoting means and having terminal portions extending therefrom to bear against said flange and said hammer, respectively.

16. In an action, for exciting the Vibrator of a musical instrument, including a vibrator-striking hammer and movable actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering to the hammer an inpact opposing a rebound of the hammer from the actuating means, said device comprising an oscillating system, formed by cooperating mass and compliance, subjected by the actuating means to internal movement simultaneously with at least the terminal portion of the movement of the hammer by th-e actuating means and subjected to further internal movement by its own inertia after the hammer strikes the vibrator.

17. In an action, for exciting the vibrator of a musical instrument, including a vibrator-striking hammer and movable actuating means therefor against which the hammer may rebound after striking the vibrator: an anti-rebound device for delivering yto the hammer an impact opposing a rebound of the hammer from the actuating means, said device comprising an oscillating system, formed by cooperating mass and compliance, both bodily and internally movable, subjected by the actuating means to both bodily and internal movement simultaneously With at least the teminal portion of the movement of the hammer by the actuating means and subjected to further internal movement by its oWn inertia after the hammer strikes the vibrator.

' BENJAMIN F. MIESSNER.

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

UNITED STATES PATENTS Number Name Date 770,889 Billings Sept. 27, 1904 1,194,754 Lanchester Aug. 15, 1916 1,353,644 George Sept. 2l, 1920 1,598,203 Laukandt Aug. 31, 1926 1,729,528 Todd Sept. 24, 192.9 1,806,595 Cameron May 26, 1931 2,082,548 Pape June 1, 1937 2,271,460 Meissner Jan. 27, 1942

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