US2469568A - Piano action - Google Patents

Description

May 10, 1949- B. F. MIEISSNER PIANO ACTION Filed D60. 7, 1944 DQZOUUQ b0 .06 0 MO ND Q0 "OI-LOW 8301"?" IN V EN TOR. BENJAMIN FMESSNER.

Patented May 10, 1949 UNITED STATES LZATENT OFFICE which the speed of repetition for rapid playing is.

not affected by the means for suppressing the rebound'of the hammers.

In addition, the invention has for its object to simplify the construction and arrangement of the novel piano action.

Other objectswill appear from the description hereinafter, and the features of novelty'will be pointed out in the claims.

In the accompanying drawings which illustrate air example of the invention without defining its limits,

Fig. 1 is an elevation illustrating the novel action;

Fig. 2 is a fragmentary enlarged view of the rebound suppression means; and

Fig; 3 is an oscillogram diagrammatically illustrating the operation of the novel piano action.

In the form illustrated in Fig. l, the reference numeral I indicates the key bed which constitutesa part of the piano case in the conventional manner, and supports the key frame 2 on which thexkey '3 is pivotally mounted on the balance pin 4 and pad 5. A guide pin 6 and pad! are provided inthe customary manner at the forward striking end 3-0. of the key 3. At its rear end, the key 3 is continued in the form of a downwardly extending, preferably inclined, arm 3-b provided near its free end with an inserted plug 8 of*1ead or other metal to constitute a Weight atuthis point, said arm 3-b normally resting on a pad 9 suitably secured in surface engagement with a rail in conveniently mounted in the case of: the piano.

The. key is further provided with a capstan screwll projecting perpendicularly to the arm 3--b, anwcarried thereby at a predetermined point-for co-operationrwith the hammer as will appear more fully hereinafter. A screw-eye 12 or. equivalent device depends from the lower .end or the aunt-12 as illustrated'in Fig. 1.

The hammer comprisesa felt head l3 mounted -on-=.the-stem M which ;in-turn'is carried .by'the.

butt i5 pivotally mounted at It, upon the flange ll. iasten-ed'by means of, a screw I8 upon therail I9.- suitably mounted in the instrument. The butt. [5. is provided with a pad E5-a which is suitably secured to said butt l5,the latter further includ-" inga second pad 15-h located beneath the pad. l5--a for the purpose of silencing noises which otherwise would develop at this point. The rail. l9 carries a pad 20 located in the path of movement'of. the key-arm -3-b and acting as a stop for the upward movement of the arm 3b when; the key 3 is operated. A hammer spring 2| is mounted on and'depends from a rail 22. suitably supported-inthe piano and has its free end in; contact with the'butt I5 of the hammer as shown... A pad 23'is'suitab1y fixed in surface .engagementr. withtheqrail 22- to act as a stop for the damperas'willlmore fully app-ear hereinafter.

The-damper head 24 is attached by means of a set screw 25 to a damper rod 26 whichin turn is carried by. the .wooden damper lever 21 influenced by a preferably wire. spring 28, and pivoted ata.29, :on a flange 38 which is attached to the rail LI 9. by means of; a screw 3 I.

The damper head is operated by the key 3 throughzthe medium of a floating link or push rod 33,rthreaded at its opposite ends, and carrying; preferably-wooden buttons 34 provided with suitably-attached felt pads 35, and tubular noise;

silencing 'rubber' or other sleeves 36, as. illus-.

- 12' and '32,-and .the sleeves 36 located in the. in.

sides there0'f,;as illustrated. Screw-threaded adjustmentrof thewooden buttons 34 on the threaded. push=rod 33 serves to selectively adjust the motion;and:action-of the damper. The piano string 31 or other vibrator may be mounted in the instrument' in the conventional manner so as to be capable of being struck by the hammer l3,.and damped by the damper 24..

The hammer is provided with a guide rod 38 preferably of Duralumin,.and includingahead 39 at its free end and a contiguous visco-elastic' pad All mounted on said rod 38,-in any convenient manner. This. Duralumin guide rod is prefer.- ably electroplated with a coating of non-oxidizing; metal" such aschromium to maintain low slidin frictiomfor the weight, M slidably mounted onthe. rod 33.,- which; also carries a compressionv spring daz'surrounding. said trod ea between the weight. M and the harnmeiz'as illustrated in Figs. 1 and: 2.. In the-preferred arrangement, the. guide rod;

3 is set into a rubber bushing 43 countersunk into the wooden tail of the hammer, and secured therein any suitable manner, as by gluing, the arrangement being such that said bushing 43 projects outwardly beyond the wooden tail of the hammer as shown.

The spring 42 is of a diameter at its hammer end to fit securely upon the protruding end of the rubber bushing 43 and gradually increases in diameter toward its mid-section and then tapers to a smaller diameter in a direction toward the weight 4!. In other words, the spring 42 tapers in opposite directions from an enlarged midsection so that when said spring 42 is fully compressed. its length is relatively small. The righthand end of the spring 42 in Fig. 1, fits snugly about the guide rod 38 to prevent vbiratory noises, and at the same time, is arranged to slide freely along the guide rod 38 when struck by the weight 4|, in the operation of the piano action.

The weight M preferably is provided with a noise-silencing leather or other bushing 4Ia impregnated with graphite as a lubricant, to facilitate the sliding movements of said weight 4|, lengthwise of the guide rod 38. Preferably, a relatively thin rubber Washer 41 is also located between the pad 4% and the weight 4i, to avoid and silence slapping noises otherwise developed,

when the weight 4| strikes the pad 40. The latter, in its preferred form, consists of a visco-elastic synthetic material having high viscosity and low elasticity such as a synthetic resin having these properties. To prevent cold flow of this material, it may be dipped in liquid rubber to coat it with a thin film of rubber 4E-a, and when this rubber film is dry, and the pad 4!] has been cemented or otherwise secured to the head 39 of the guide rod 38, the entire pad 40 may be dipped in flake graphite, which is rubbed into the rubber to prevent stickiness. For visco-elastic pads which develop no slapping noise when impacted by the weight 4|, the rubber washer 4'! may be omitted, and for pad material which is not subject to cold flow, the rubber film may also be omitted. Furthermore, for non-sticking pad material, the graphite coating may be omitted,

The hammers normally rest against a pad 48 suitably mounted in surface engagement with a rail 49, which, by conventional means not shown, may be shifted at will to the left in Fig. 1, so as to shorten the hammer stroke for soft-pedal operation. The pad 48 may also be made of viscoelastic material to suppress rebound of the hammer from said pad for strong, quickly-released key blows. For such key blows, in conventional actions, the hammer, especially of the heavy, bass type, is capable of rebounding back to the strin and re-striking the same, which objection is avoided by the use of the visco-elastic pad 48 instead of the customary felt.

The dampers 24 are also controlled by means of a conventional loud pedal lifter, not shown, which, by pushing all of the damper rods at their lower ends to the left, disengages all dampers from the strings 37, independently of the key control of said dampers.

In operation, when the key 3 is struck at its playing end 3a, the capstan screw ll exerts a pushing force against the pad l5-a, to thereby cause the hammer [3 to be moved toward the string 3 or other vibrator. The capstan screw l l remains in contact with the hammer until the latter reaches a point about of an inch from its associated string 31, at which point the key 3 and its arm 3b come to rest against the pads six 4 1 and 20, respectively. At this stage, the hammer continues its movement onward under its own momentum, and strikes the string 31 or other vibrator, from which the hammer rebounds back into contact with the capstan screw II through the pad i5-a.

The weight 41 is accelerated with the hammer, being driven by the pad 40 and guide rod 38 carried by said hammer.

When the hammer head 13 strikes the string 31 or other vibrator, and the hammer begins to lose forward velocity, the weight 4| starts to slide lengthwise of the guide rod 38 toward the spring 42, and as the hammer rebounds in the reverse direction from the string 31 or other vibrator, the weight velocity on the guide rod 38 increases. As the hammer head I 3 is about to leave the string 31 or other vibrator, the weight 4| begins to compress the spring 42, the amount of such compression varying with the force of the key blow.

As the spring 42 is thus compressed, it develops an opposing force against the hammer which somewhat reduces the velocity of the hammer toward the capstan screw l I. Part of the kinetic energy of the weight 4! is therefore utilized to slow down the velocity of the hammer as the latter rebounds from the string 3! or other vibrator, and a part of said energy is stored in the spring 42 as potential energy.

The hammer continues onward in its return movement, strikes the capstan screw I I (when the key 3 is held down) deflects the stem l4 and compresses the pads 5, I5a, and [5-17. Then, as the hammer starts to rebound back toward the string 37 or other vibrator, the weight M is driven by the compressed spring 42 against the rubber washer and visco-elastic pad 40 on the guide rod 38, with just the right amount of force to neutralize the tendency of the hammer to rebound toward the string 31.

I have found that, with leather or felt pads at 5, l5a, and |5b, the weight of the element 4| should be 0.2 times the weight of the associated hammer, as measured with the hammer stem 14 horizontal and the hammer flange ll fixed, as in a vise.

The oscillogram illustrated in Fig, 3 shows diagrammatically, the hammer motion with the instant improved and novel anti-rebound attachment.

The hammer leaves its normal position of rest on the pad 48 of the back rail 49, as the key 3 is struck, and gains velocity until the driving motion of the key 3 is stopped by the pads 1 and 22 when the curve crosses the line A. Thereafter, the hammer continues its motion until it strikes the string 31 or other vibrator where the curve crosses the line B. The hammer then slows down, comes to a stop at C, and reverses its direction of movement back to the capstan screw I I, which it recontacts as the curve recrosses the line A. When the key 3 is held down following the key blow, the capstan screw 1 l remains in fixed position corresponding to the line A of the hammer curve. The hammer, therefore, strikes the capstan screw l I through the intervening pad l5-a, and, due to eompliances in the hammer stem 14, pads I5-a, [5-11, and 5, and elsewhere in the key assembly, the hammer deflects back to the point D in the curve, after which it again reverses its motion toward the string 31 or other vibrator. Just as the hammer is about to leave the capstan screw II at point F of the curve, the weight 4|, impelled by the spring 42, strikes the rubber W-G'Shfirll and pad 401,, and thereby brings the hanmrento-rmtupm andiiniengagement with the eapstamscnew It.

Iir teaseswhere: the key 3 i is not: held. down: following: thakey blow, as in rapid-repetition, the hammer continues on backward from the-string 31: on other vibraton. along the dotted line until it recontactsthercapstan screw i l' Or the pad on therback raiiiM Inithis'cas-ei. the weight M strikes the pad 40 while: the hammer moving inthe direction, and thus somewhat accelleratesthe return motion oi said hammer back: to its normal position: In thismannenthespeed ct repetition of the: hammer is unimpaired by the anti-rebound attachment ot the guiderrod' and weight assembly.

The operation" of: the anti-reboundmeansis effective at allhammer velocities due tot-he fact that'the spring '4"2-1feg-u12tes theieffective'forward and rearwardi stroke oiv the Weight 4!. This stroke oir'tra-vel distance, islargest for high ham mer' velocities and smallest for lowest hammer velocities; the velocityof the weight il being equal to the: hammervelocity for all key blows ofevery strength;

The amount oft kinetic energyrequiredin the weight M to neutralize the kinetic energy ofthe hammer and bring. it.v to rest without rebounding back to the string 31 or other vibrator, is considerably lower than that required to effect this operation in the manner disclosed in-my copending application, Serial No. 556,166, filed September 28, 1944. This is due to the fact that con-- siderable of the residual kinetic energy in the hammer, after it leaves the string or other vibrator, is dissipated in the various compliances during its.- rearward deflection. after recontacting the capstan screw. The velocity of thehammer as'it beg-insto leave the capstanscrew in areturn movement toward the string, is, therefore, considerably-lower than its velocity on leaving the string. Since its kinetic energy is proportional to the square of its velocity, this reduction in its velocity before neutralization by the loose weight 4|, is important in reducing the amount and dimensions of this loose weight 429 necessary for efiicient operation.

The reduction in the velocity of the hammer at the point F of the curve in the oscillogram of Fig. 3, just before the weight M strikes the pad 40, may be increased by choosing, for the pads l5a or l5b or fOr both of these on the hammer butt i5, suitable material having viscous damping properties which will still further absorb kinetic energy from the hammer. This makes possible a still further decrease in the weight of the mass 4!, required to prevent rebound of the hammer back towards the string 3! or other vibrator.

In the same manner, the pad 5 beneath the key 3 on the balance rail pin 4, may also be made of visco-elastic material since thi pad 5 is compressed when the hammer strikes the capstan screw II. It will also assist in absorbing kinetic energy from the hammer so as to reduce the amount thereof requiring neutralization.

I have found that by the use of these viscoelastic pads at 5. l5a,, and Iii-b, the hammer velocity is so much reduced as the hammer begins to rebound from the capstan screw back to the string, that the weight of the loose mass represented by the weight 4!, may be reduced to approximately 13% or less of the weight of the hammer with its stem horizontal and its flange fixed in a support, as against a 21% weight of loose. mass with" conventional leather and: ,felt pads. To; preventtcold? flow." of these-pads when the latter are'subject. to. such; fiow said; pads may be encasedin a thinrubberskinor. film: by dip.- ping them in rubber, drying, and; covering with graphite. Ifthe pads 5; l:5a,. and |.5-b are sufficiently eiiective to. absorb all. the residual kinetic energy of the hammer for maximum strength or key blow so as to prevent. hammer. rebound from the capstan screw back to; the string, the anti-rebound attachments 38, 39, 40', t-i, 22,.andi 47 maybeomitted- I have foundthat the guiderods 38" maybe of the same length for all hammer sizes, and that the springs 32 may b'e'ot the samersize and stiffness" for all hammer sizes. The purpose of, the rubber bushing 43 is toprevent the shock impulse, set up by the Weight 4| when striking the pad. dd, from being comm unicated. to the hammer head !3 and through its stem. l4- and flangehl l into the structure ot the piano from which it radiatesas an. impact, noise- Although the present invention has; beendescribed in conjunction with a preferred embodiment, it is to be understood. that modifications and'variationsmay beresorted towithout departing from the. spirit and scope oi the invention, as those-skilled-in the. art willreadily understand. For instance, the sliding or suppression weights may be replaced by loose masses of granular, solid. or. liquid: type contained in a tubular part of or attachment to. the hammer; Such variations. and modificationsare considered to be with.- in the purview and scope of. the claims.

I claim:

1. In a musical instrument of the pianoty-pe, a vibrator, a hammer movably mountedinstriking relation to said vibrator, a movably mounted operating key, actuating means operated by said key effective onv said hammer to cause the latter to strike said. vibrator, a rebound suppressing weight associated with saidzhamrner" and movable relatively thereto, and a spring co operating with said weightto reduce the velocity of. the return movement-of the hammer from the vibrator, andto neutralize rebound. of said hammer relatively to said actuating means. upon the return of the hammer thereto subsequently to its impact against said vibrator.

2. In a musical instrument of the piano type, a vibrator, a hammer movably mounted in striking relation to said vibrator, a movably mounted operating key, actuating means operated by said key effective on said hammer to cause the latter to strike said vibrator, guide means carried by said hammer and extending in the direction of its operative movements, a rebound suppressing mass movable relatively to said guide means as said hammer is operated, and a spring acted on by said mass to reduce the velocity of the return movement of the hammer from the vibrator, and to neutralize rebound of said hammer relatively to said actuating means upon the return of the hammer thereto subsequently to its impact against said vibrator.

3. In a musical instrument of the piano type, a vibrator, a hammer movably mounted in striking relation to said vibrator, a movably mounted operating key, actuating means operated by said key efiective on said hammer to cause the latter to strike said vibrator, a guide rod carried by said hammer and extending in the direction of its operative movements, and a rebound suppressing means including a weight slidable lengthwise of said rod for reducing th velocity of the return movement of the hammer from the vibrator, and for neutralizing rebound thereof relatively to said actuating means upon the return of the hammer thereto subsequently to its impact against said vibrator.

4. In a musical instrument of the piano type, a vibrator, a hammer movably mounted in striking relation to said vibrator, a movably mounted operating key, actuating means operated by said key efiective on said hammer to cause the latter to strike said vibrator, a guide rod carried by said hammer and extending in the direction of its operative movements, a rebound suppressing weight externally carried by and slidably mounted on said rod, a head carried by said rod in the path of movement of said weight in one direction, and a rebound suppressing spring carried by said rod in the path of movement of said Weight in the opposite direction, and arranged to be coll pressed thereby to reduce the velocity of the return movement of the hammer from the vibrator, and to force said weight against said head to neutralize rebound of said hammer rela ively to said actuating means subsequently to its impact against said vibrator.

5. In a musical instrument of the piano type, a pad of visco-eiastic, energy-absorbing material, and an elastic film encasing said pad and having sufiicient resiliency to allow said pad to deform under pressur and to restore said pad to its normal shape when the pressure is relieved.

6. In a musical instrument of the piano type, a pad of visco-elastic, energy-absorbing material, and a rubber skin encasing said pad and having sufficient resiliency to allow said pad to deform under pressure and to restore said pad to its normal shape when the pressure is relieved.

7. In a musical instrument of the piano type, a vibrator, a hammer movably mounted in striking relation to said vibrator, an operating key in operative association with said hammer to cause the latter to strike said vibrator, a rail, and a pad of visco-elastic material on said rail against which said hammer normally rests and to which it returns subsequently to its impact against the vibrator, said pad suppressing rebound of said hammer therefrom subsequently to said return thereto.

8. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movabl to strike the vibrator; actuating means for moving the hammer and against which the hammer rebounds after striking the vibrator; means, rendered effective by the striking of the vibrator by the hammer, for storing kinetic energy in potential-energy form during the rebound of the hammer from the vibrator; and means rende 'ing the stored energy effective to oppose a rebound of the hammer from the actuating means.

9. In a musical instrument, an exciting action for a vibrator comprising, in combination, a hammer movable to strike the vibrator; actuating means for moving the hammer and against which the hammer rebounds after striking the vibrator; a mass moved by said actuating means coincidentally with the movement of the hammer by the actuating means, and movable relative to the hammer; resilient means regulating the motion of said mass relative to the hammer upon the striking of the vibrator by the hammer; and means, forming a portion of the hammer, against which said mass delivers an impact when the hammer has rebounded against the actuating means.

BENJAMIN F. MIESSNER.

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

UNITED STATES PATENTS Number Name Date 1,167,863 West Jan. 11, 1916 1.184181 Holden May 23, 1916 1,598,203 Laukandt Aug. 31, 1926 2,082,548 Pape June 1, 1937 2,226,877 Schulze Dec. 31, 1.940 2,288,852 Socin July 7, 1942 2,329,009 Socin Sept. 7, 1943 FOREIGN PATENTS Number Country Date 206,732 Germany Feb. 10, 1909 530,257 Germany July 25, 1931

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