US2976756A - Magnetic control means for piano dampers - Google Patents

Description

March 28, 1961 J. SCHWARZBAUR MAGNETIC CONTROL MEANS FOR PIANO DAMPERS Filed Oct. 22, 1957 2 Sheets$heet 1 R O T N E V m /M'r ATTORNEY March 28, 1961 J. SCHWARZBAUR MAGNETIC CONTROL MEANS FOR PIANO DAMPERS Filed Oct. 22, 1957 2 Sheets-Sheet 2 INVENTOR @fzz/z'zulft'iwarzazzz" BYQQM fi ATTORNEY United States Patent MAGNETIC CONTROL MEANS FOR PIANO DAMPERS Julius Schwarzbaur, 516 E. 80th St., New York 21, N.Y. Filed Oct. 22, 1957, Ser. No. 691,700

11 Claims. (Cl. 84216) The present invention relates to piano actions in general, and more particularly to improved means for preventing overtones, aftervibrations and sympathetic vibrations of piano strings.

An object of the invention is to provide improved means for reducing sympathetic vibrations and aftervibrations of piano strings which are particularly felt in the bass and middle sections of a piano-like key-operated musical instrument.

Another object of the invention is to provide improved means acting under the influence of a constant magnetic field for rapidly returning the dampers back into contact with the strings when the piano keys are released.

A further'object of the invention is to provide permanently acting means between each piano key and its damper for preventing sympathetic vibrations and for more rapidly returning the dampers into contact with the strings when the keys are released.

An additional object of the invention is to provide a mechanism of the above character which does not influence, and requires no changes in, the touch of piano keys once its component parts are installed in the action.

A still further object of the invention is to provide improved means of the above described character consisting of simple and inexpensive parts which may be installed in all types of pianos and similar key-operated musical instruments.

A yet further and more specific object of the invention is to provide improved means adapted to generate permanently acting forces between the dampers and such other parts of a piano action which are set in motion when the key is depressed.

In accordance with a feature of the instant invention, a pair of closely adjacent permanent magnets is provided for each key of a piano-like instrument. One magnet is mounted on the damper lever, damper guide, or another part of the damper mechanism, and the other magnet is mounted either directly on the piano key or is attached to such part of the action which follows the movements of the key toward and away from the damper mechanism when the key is depressed or released.

In a grand piano, one magnet may be attached directly to the inner end of the key, i.e. to that end of each key which is distant from its playing end and at the opposing side of the point about which the key pivots; and the other magnet may be attached to the underlever of a damper, i.e. to that part of the damper mechanism which supports the damper wire and is closely adjacent to the inner end of the key.

In an upright piano, one magnet is preferably mounted in that end of the damper lever which is remote from the damper block, and the other magnet may be incorporated in the damper spoon which, for such purposes, is suitably formedto augment the attracting force between the magnets and to thus insure rapid return of the damper fell back into contact with the string when the key is released.

Other objects of the invention as well as additional 2,976,756 C Patented Mar. 28, 1961 features, advantages and attributes of the novel mechanism will become apparent in the course of the following detailed description of certain preferred embodiments which are illustrated in the accompanying drawings, and the invention will be finally pointed out in the appended claims;

In the drawings:

Fig. 1 is a partial diagram of a grand piano action with the hammer in idle position and showing the magnets built into the damper underlever and into the inner end of the piano key, respectively;

Fig. 2 is a fragmentary view of the structure shown in Fig. l with the hammer in an intermediate position;

Fig. 3 illustrates the structure of Fig. 2 with the hammer in operative position in contact with the piano string;

Fig. 4 is an enlarged view of the magnets;

Fig. 5 is an enlarged section through the inner end of a grand piano key, showing one mode of securing a magnet thereto;

Fig. 6 is a section taken substantially at right angles to the section of Fig. 5, showing a slightly different mag net;

Fig. 7 is a partial diagram of an upright piano action showing the magnets built into the damper lever and in the damper spoon, respectively; and

Fig. 8 is an enlarged perspective detail view of the magnets shown in Fig. 7.

Referring now in greater detail to the drawings, and first to Fig. 1 which illustrates a grand piano action, there is shown a frame 10 for the piano key 11 which pivots about the rail pin 12 when its playing end (not shown) is depressed. Action frame 13 carries the wippen 14 whose lower end abuts against the capstan screw 15 to move the repetition lever 16 against knuckle 17 on hammer shank 18 when the playing end of key 11 is depressed, whereby the hammer head 19 pivots about pin 20 and moves in upward direction against and into contact with the string 21. To the underlever frame 22 is attached a flange 23 which pivotally supports the damper underlever 24. Underlever top flange 25, pivotally connected to member 24, carries the damper wire 26 which in turn supports the damper head 27 in such manner that damper felts 28 normally rest against the string 21 when the key 11 is at rest. The above described action and the manner of its operation are well known in the piano art.

A plate-like permanent magnet 29 is recessed into the upper face of key 11 at its inner end 11a. A second and similar magnet 30 is recessed in the underlever 24, and a layer 31 of felt is glued to the upper face of magnet 29 so as to prevent direct contact between the magnets and thus any contact noises or clicks when the magnets 29 and 30 are moved toward each other, as such clicks would interfere with the sound produced by the piano strings.

Magnets 29 and 30, even if the key 11 is at rest, are sufiiciently close to each other and the attracting force therebetween is sufficiently large to urge the upper magnet 30 toward the lower magnet 29 and to thus force the felts 28 on damper head 27 into firm contact with the string or strings 21. This elimnates sympathetic vibrations of strings when another key is depressed, especially in the bass and middle sections of the piano.

As may be observed in Fig. 2, upon depression of the key, its inner end 11a moves with magnet 29 in upward direction toward the magnet 30 to bring the felt layer 31 into contact with the latter. The hammer head 19, too, by way of capstan screw 15, wippen 14, repetition lever 16, knuckle 17 and shank 18, is moved toward the string and already describes an arc corresponding to about 40 percent of its overall travel before the felt 31 comes into contact with the underside of the upper magnet 30.

'- I p I 2,978,756 r Upon further depression of key '11, the underlever 24,

with top flange 25, damper wire 26 and damper head 27 moves in upward direction so as to move damper felts 28 away from contact with the string before the hammer head 19 strikes thereagainst. This position of the action parts is shown in Fig. 3.

When the key is released, the closely adjacent magnets 29 and 30, separated only by a distance corresponding to the thickness of felt layer 31, even more strongly attract each other and the damper head descends very rapidly following the descent of the inner end 11a of the now released key 11. String 21 is thus silenced practically'immediately after its key is released since the damper descends not only by its own weight but also under the influence of constant magnetic field acting between elements 29 and 30. This eliminates undesirable aftervibrations.

As is known, a more rapid descent of piano dampers is customarily accomplished by the insertion of one or more lead weights into the underlever 24. One such weight is shown at 32 in Figs. 1 to 4. This arrangement, how- 'ever, is insufficient and especially sympathetic vibrations may be heard even if more than one weight is provided in the underlever. Moreover, care must be taken that the weights do not overly change the touch of piano keys, as each key must be carefully balanced and adjusted so as to require a predetermined finger pressure for its depression.

The magnetic force acting between members 23 and 30 must be stronger in the bass and middle sections than in the treble section of the piano. Thus, smaller or weaker magnets may be employed in the treble section, or a larger felt layer may be used in this section to reduce the exposed area of that magnet to which the felt is attached.

The use of electromagnets in place of permanent magnets, while possible, is less desirable because of expensive wiring, solenoids and many other component parts which add to the overall cost of the instrument. Moreover, in addition to costs due to constant current consumption, maintenance of such electrical equipment is rather expensive, whereas permanent magnets, when properly aged, are practically indestructible and require no further attention once they are built into the piano action.

Fig. 4 illustrates magnets 29 and 3t) on a substantially larger scale. It will be noted that the head of at least one of screws 33 passing through the lower magnet 23 and into the inner end 11a of the key 11 is covered by the felt layer 31, and that the screws 34 passing through magnet 3% and into the underlever 24 are on that side which comes into contact with the felt layer 31 so as to provide relatively large unobstructed surfaces for the action of magnetic attracting force between the two magnets. A thin felt layer 56 is provided between the magnet 29 and the key end 11a to prevent any audible sounds if the screws 33 should become loose. A similar felt layer 57 is shown between magnet 34 and underlever 24.

As is shown in Fig. 5, magnet 29 may be held in its recess in the inner end 11a of the key by means of a single screw 33 whose head is totally hidden beneath the felt layer 31.

Fig. 6 illustrates a slightly modified magnet 35 having at its underside an elongated bead 36 of circular crosssectional contour which fits snugly into a groove 37 of complementary contour provided in the upper face of the recessed portion at the inner end 11a of the grand piano key 11. A single screw 33 is suflicient to prevent any displacement of magnet 35. Obviously, the upper magnet 30 in the damper underlever 24 may be installed in a similar manner.

The magnets may be built into the action before the keys are balanced so as to have no effect on the touch of piano keys once the latter are properly adjusted. The constant magnetic field between the magnets, while sumciently strong to cause more rapid descent of the damper mechanism, is not strong enough to slow down the movement of key 11 when the latter descends into its position of rest since the overall weight of the wippen, of the key itself and of certain other parts of the action is sufficient to quickly return the key into the position shown in Fig. 1.

In Fig. 7, the magnets are shown in an upright piano action. The inner end 40a of key ltl carries a capstan screw 41 which abuts against the underside of wippen 42, the latter pivotally supporting a flange 43 which is fixed to the action rail 44. Action rail 44 supports the damper lever flange 45 to which is pivotally fixed the damper lever 46 carrying the damper wire 4'7 with the damper block 48 and damper felts 49. These felts, in the position illustrated in Fig. 7, abut against the string 50. Whippen 42, adjacent to the lower end 46a of the damper lever, carries a modified spoon 51 which acts in a manner similar to that magnet 29 shown in Figs. 1 to 3. Thus, the upper part of the spoon which normally has its convex face turned toward the felt layer in the lower end 4611 of the damper lever, is suitably enlarged to form a preferably rectangular plate 52 of permanent magnetic characteristics. A second magnet 53 is recessed in the lower end 46a of the damper lever and held therein by means of two screws 54. A layer of felt 55 is glued to the exposed face of magnet 53 to prevent audible contact noises when the two magnets are moved toward each other. In other words, the purpose of felt layer 55, which may be carried by either of the two magnets, is to prevent actual contact therebetween. Spoon 51 with magnet 52, magnet 53, and the felt layer 55 are shown in perspective view drawn to a larger scale in Fig. 8. In their position shown in Figs. 7 and 8, ie when the key 4% is at rest, the distance between magnets 52, 53 is about one-eighth of an inch. A felt layer 53 is shown between magnet 53 and lower end and of the damper lever to prevent noises if the screws 54 should become loose.

In operation, upon depression of the playing end (not shown) of key 40, its inner end 46a is lifted whereby the capstan screw 41 pivots wippen about its flange 43 and causes the hammer shank 5% with the hammer head (not shown) to move toward the string 5d. The pivoting wippen 42 also entrains the spoon with its magnet 52 toward the magnet 53 in the damper lever 45 so that the magnet 52 abuts against the felt layer 55 causing the damper lever to pivot in the direction of arrow A, where by the felts 49 are moved away from the string 59. In the very instant when the key "it; is released, the magnetic force acting between now closely adjacent magnets 52 and 53 causes the damper lever 46 and thus also damper felts 49 to immediately rebound into rest position in which the felts are in contact with the string Sill. Thus, vibrations of the string are prevented simultaneously with the release of key 46'. The constant magnetic force acting between magnets 52, 53 also prevents any sympathetic vibrations even though the distance between the magnets is now greater than in the position when the damper felts are lifted away from the piano string.

The manner of attaching magnet 53 to the damper lever 46 may be the same as previously shown in Figs. 4 and 5 or in Fig. 6.

It will be seen that I provide an improved system for preventing overtones, aftervibrations and sympathetic vibrations of piano strings, this system comprising two magnets which maintain tberebetween magnetic field acting in a direction to constantly urge the damper into contact with the string at least when the key is in its released position. One of the magnets is always moved when the piano key is pivoted to its depressed position so as to lift the damper 27, 28 or 43, 49 away from the string, and the other magnet may be connected with a stationary or with a movable part, depending on the exact location of the moving magnet. Thus, in Fig. 1, the magnets 29, 30 are bodily displaced when the key 11 is depressed because the magnet 30 is carried by the lever 24 which forms part of the damper operating means and because the magnet 29 is carried by the lefthand end portion 11a of the key 11 which, in this embodiment, constitutes the key-operated means, the keyoperated means of Fig. 7 comprising the parts 40a and 4145. Thus, it can be said that the damper operating means and the key-operated means form an assembly which includes two magnet-carrying parts at least one of which moves when the key 11 is depressed while the other may but need not move in response to the depression of the key.

The invention is, of course, not limited to the specific details of construction shown and described hereinabove, but may be embodied in a number of further modifications within the spirit and scope of the appended claims. For example, the magnets may be fastened to the respective action parts without any screws or by means of suitable fastening elements not terminating in the opposing surfaces of the magnets. Furthermore, the size and shape of the magnets may be changed, the important requirement being that suificient attraction exist between the magnets to prevent sympathetic vibrations and to insure immediate contact of damper felts with the respective piano string or strings when the key is released.

What I claim and desire to protect by Letters Patent is:

1. In a piano action, in combination, a string; a damper; damper operating means cooperating with said damper for moving the same into contact with and away from the string; a key movable between a depressed and a released position; key-operated means cooperating with said damper operating means for actuating the latter to move the damper away from the string when the key is moved to its depressed position; a first permanent magnet carried by said damper operating means; and a second permanent magnet carried by said key-operated means adjacent to said first permanent magnet, said magnets maintaining therebetween a magnetic field acting in a direction to constantly urge said damper into contact with the string at least when the key is in said released position.

2. The structure as set forth in claim 1, wherein each of said magnets has a surface turned toward the other magnet and further comprising a layer of felt like material connected to and partially covering one of said surfaces.

3. The structure as set forth in claim 1, wherein said damper operating means comprises a stationary flange, a lever hinged to said flange and pivotable by said keyoperated means, and means for connecting said lever with said damper, said first magnet being connected with said lever.

4. The structure as set forth in claim 3, wherein said first magnet is recessed in said lever.

5. The structure as set forth in claim 3, wherein said first magnet is connected to said lever in tenon and mortise fashion.

6. The structure as set forth in claim 1, wherein the second magnet is connected to said key operated means in tenon and mortise fashion.

7. The structure as set forth in claim 1, wherein said second magnet has a surface turned toward said first magnet and further comprising a layer of felt like material connected to and partially covering said surface for preventing contact between said magnets when the key is pivoted into said one position, and at least one screw for connecting the second magnet with said key, said screw having ahead covered by said layer.

8. In a piano action, in combination: a key having an inner end, a playing end, and pivotable about an axis intermediate said ends; a string; a damper having a member movable into contact with and away from the string, and a lever adjacent to, disposed above, and pivotable by the inner end of said key in a direction to move said member away from the string; and means for maintaining a permanent magnetic field between the inner end of said key and said lever and acting in a direction to urge said member into contact with the string, said means comprising a first permanent magnet connected to said lever and a second permanent magnet connected to the inner end of said key adjacent to said first magnet.

9. In a piano action, in combination: a key having an inner end, a playing end, and pivotable about an axis intermediate said ends; an action rail; a wippen articulately connected with said rail and pivotable by the inner end of said key when said playing end is depressed; a string; a spoon connected to said wippen, at least one portion of said spoon constituting a permanent magnet; a damper articulately connected to said rail and comprising a member movable into contact with and away from the string, and a lever connected with said member; and a second permanent magnet connected with said lever adjacent to said spoon and maintaining with the latter a magnetic field acting in a direction to constantly urge said member into contact with the string, said member being moved away from the string when said wippen is pivoted by the inner end of said key whereby the spoon pivots said lever.

10. In a piano action having a bass section, a middle section and a treble section, in combination: a plurality of strings in each of said sections; a plurality of keys; dampers operable by said keys and each comprising a member normally in contact with at least one string and movable away from contact therewith by the respective one of said keys; :1 first permanent magnet connected to each of said dampers; and a second permanent magnet installed in said action adjacent to each first magnet and each movable by a selected key toward a respective first magnet, said magnets maintaining therebetween a magnetic field acting in a direction to constantly urge said members into contact with respective strings, the magnetic fields in said bass and middle sections being stronger than in said treble section.

11. In a piano action, in combination, a string; a damper; damper operating means cooperating with said damper for moving the same into contact with and away from the string; a key movable between a depressed and a released position; key-operated means cooperating with said damper operating means for actuating the latter to move the damper away from the string when the key is moved to its depressed position, said damper operating means and said key-operated means forming an assembly which includes two parts at least one of which moves when said key is moved to its depressed position; and a pair of permanent magnet means respectively carried by said parts and maintaining between themselves a magnetic field which acts in a direction constantly urging said damper into contact with said string at least when the key is in said released position.

References Cited in the file of this patent UNITED STATES PATENTS 468,918 Perry Feb. 16, 1892 595,458 Nickel Dec. 14, 1897 962,261 Rose et a1. June 21, 1910 2,263,088 Hofmann Nov. 18, 1941 2,500,172 Gillenwater Mar. 14, 1950 FOREIGN PATENTS 390,213 Great Britain Apr. 3, 1933 893,611 Germany Oct. 19, 1953

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