United States Patent: 3554071

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United States Patent	3,554,071
Klaiber	January 12, 1971

PLASTIC PIANO ACTION

Abstract

The butt flange of a piano action is molded of a plastic material, a preferred example being polypropylene. In one embodiment of the invention the butt flange is provided with a relatively thin section so that the pivot pin for the hammer butt is capable of translatory movement. A spring holds the butt flange against such flexing, and precludes such translatory movement of the pivot unless the key is struck with greater than normal force. In another embodiment of the invention the pivot is eliminated and the hammer butt, and preferably also the shank, is made integral with the butt flange, the section between the butt flange and the hammer butt being thin to permit flexing and movement of the hammer toward and away from the sounding element.

Inventors:	Klaiber; Geroge Stanley (Tonawanda, NY)
Assignee:	The Wurlitzer Company (Chicago, IL)
Appl. No.:	04/742,630
Filed:	July 5, 1968

Current U.S. Class: 84/237 ; 84/251

Current International Class: G10C 3/00 (20060101); G10C 3/22 (20060101); G10c 003/18 ()

Field of Search: 84/236,237,238 29/149.5NM 84/251,252,404,405,1.13,1.14

References Cited [Referenced By]

U.S. Patent Documents


2610358	September 1952	Martin
2641828	June 1953	Knoblaugh
2881509	April 1959	Gadebusch
2948180	August 1960	Wood

Foreign Patent Documents


575,768	., 1959	CA
696,924	., 1953	GB

Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Gonzales; John F.

Claims

I claim:

1. A piano action including base means, a key movably mounted on said base means and adapted for manual actuation, a vibratile element carried from said base means, a hammer having a butt and percussively engageable with said vibratile element to actuate said vibratile element, means pivotally mounting said hammer on said base means, and means operatively connecting said key and said hammer for pivotally moving said hammer into percussive engagement with said vibratile element upon manual actuation of said key, said hammer mounting means including a flexible plastic element having a minimum dimension in the direction of pivoting to promote flexibility in that direction and having a substantially greater dimension laterally thereof to promote lateral stability.

2. A piano action as set forth in claim 1 wherein said plastic element is of a predetermined thickness such as to be generally inflexible, and has a thinner flexural area of said minimum dimension.

3. A piano action as set forth in claim 1 wherein said hammer mounting means includes a butt flange and said flexible plastic element extends between said butt flange and said butt.

4. A piano action as set forth in claim 2 wherein said hammer mounting means includes a butt flange and said plastic element extends between said butt flange and said butt.

5. A piano action as set forth in claim 3 wherein said hammer butt is of the same plastic material as said flexible plastic element and is integral therewith.

6. A piano action as set forth in claim 5 wherein said plastic element has a predetermined thickness sufficient to inhibit flexing, and further has a thinner flexural area having said minimum dimension.

7. A piano action as set forth in claim 3 wherein said butt flange is of the same plastic material as said flexible plastic element and is integral therewith.

8. A piano action as set forth in claim 7 wherein said plastic element is of a sufficient thickness to resist flexing and has a thinner flexural area of said minimum dimension.

9. A piano action as set forth in claim 7 wherein said hammer has a butt of the same plastic material and is integral with said flexible plastic element.

10. A piano action as set forth in claim 9 wherein said flexible plastic element has a predetermined dimension such as to resist flexing and has a thinner flexural area of said minimum dimension.

11. A piano action including base means, a key mounted on said base means and adapted for manual actuation, a vibratile element carried from said base means, a hammer having a butt and a head movable toward said vibratile element for percussive engagement therewith to actuate said vibratile element, means pivotally mounting said hammer on said base means and including a butt flange fixed on said base means and a connection between said hammer and said butt flange permitting pivoting of said hammer, and means operatively connecting said key and said hammer for pivotally moving said hammer into percussive engagement with said vibratile element upon manual actuation of said key, said butt flange including a transversely movable flexible plastic element flexible substantially in the direction of movement of said hammer head to permit dynamic shifting of said connection in response to heavy keying to limit the energy transferred to said hammer.

12. A piano action as set forth in claim 11 and further including a preloaded spring fixedly mounted on said butt flange and operatively engageable with the flexible plastic element of said butt flange to prevent flexing of said flexible plastic element until a keying force is applied to said hammer of sufficient magnitude to overcome the preloading of said spring.

13. A piano action as set forth in claim 12 wherein said hammer butt is connected to said butt flange by a pivot pin.

14. A piano action as set forth in claim 12 wherein said pivotal connection between said hammer butt and said butt flange comprises a flexible plastic element.

15. A piano action as set forth in claim 14 wherein said hammer has a butt, said hammer butt, said butt flange, and both of said flexible plastic elements being integrally fabricated of the same plastic material.

16. A piano action as set forth in claim 12 wherein said butt flange comprises a plastic part of sufficient thickness to resist flexing and said flexible plastic element comprises an integral plastic section of thinner dimension in the direction of pivoting to promote flexibility in that direction and having a substantially greater dimension laterally thereof, and wherein said preloaded spring spans said flexible plastic element.

17. A piano action including base means, a key movably mounted on said base means and adapted for manual actuation, a vibratile element carried from said base means, a hammer having a butt and a head movable toward said vibratile element for percussive engagement therewith to actuate said vibratile element, a butt flange mounted on said base means, said butt means providing means pivotally mounting said hammer, and means operatively connecting said key and said hammer for pivotally moving said hammer into percussive engagement with said vibratile element upon manual actuation of said key, said pivotal mounting means being translatable in the direction of movement of said hammer head substantially to effect a nonlinear transfer of energy from said key to said vibratile element.

18. A piano action as set forth in claim 17 wherein said butt flange comprises two main parts one of which is fixed relative to said base means and the other of which is pivotally connected to said butt, and a yieldable connection between said two main parts.

19. A piano action as set forth in claim 18 and further including resilient means acting between said butt flange two main parts and preloaded so that the part having the butt pivoted thereon yields upon transfer of energy to said hammer from said key with a force greater than the preloading.

20. A piano action as set forth in claim 19 wherein a spring comprises the resilient means acting between the butt flange two main parts.

21. A piano action as set forth in claim 20 wherein said spring comprises a blade spring.

22. A piano action as set forth in claim 18 wherein said butt flange two main parts and the yieldable connection are integrally fabricated of a plastic material, and further including a blade spring acting from one main part of said butt flange to the other main part of said butt flange and preloaded to allow moving of the butt flange part to which the hammer butt is pivoted upon excessively heavy manual operation of said key.

Description

Piano actions have, from the time of their inception, commonly been made of wood. Hammers have been made of a plurality of wooden parts glued together, with the hammer butt being pivoted onto the butt flange by a steel pin, with the bearing surfaces bushed with felt. As will be appreciated, a great deal of hand labor is necessary for the building of a conventional piano action. In addition, wood changes dimension quite noticeably with the amount of moisture in the air, and hence with the amount of moisture absorbed by the wood. Thus, parts may tend to tighten up and bind, or to loosen and be noisy.

An electronic piano is manufactured by the Wurlitzer Company utilizing vibrating reeds rather than strings as the sounding elements. Each reed is tuned to correspond to one of the notes, and the several reeds are in capacitive relation with a pickup plate. The electrical capacity between the reeds and plate varies with the vibration of the reeds, and the variation in capacity is detected electrically, amplified, and applied to a loudspeaker system to produce pianolike tones. The piano in question is much smaller and lighter than a conventional string piano, weighing well under a 100 pounds. This has led to use of such a piano in combination with electric guitars, portable organs, and the like. Players of such instruments are prone to excesses, and it has been found that pounding on the keys of this electronic piano in time causes some of the reeds to break.

It has been determined experimentally that playing of the electronic piano in normal fashion causes the degree of reed excursion to vary on a not quite linear bases within a range that does not cause reed breakage. The almost linear excursion plotted against force of key strike continues beyond the normal range, and it is this that leads to reed breakage. Reed breakage can be substantially eliminated by preventing overexcursion of the reeds, and specifically by holding the maximum reed excursion to about the maximum produced by normal loud playing of the electronic piano. However, this must not be done by depressing the entire response curve, as the more quietly played notes then would not be heard at all.

Accordingly, it is the principal object of the present invention to produce piano action parts of a molded plastic material eliminating the deficiencies of wooden action parts.

A further object of the present invention is to provide a one-piece hammer butt and butt flange molded of flexible plastic material.

Another object of the present invention is to provide, in a piano action, a plastic butt flange having a hammer connected thereto by a pivot pin, with the pivot pin fixed in position for normal usage, but capable of translatory movement upon too vigorous depression of the corresponding key.

Yet another object of the present invention is to provide, in a piano action, a plastic butt flange having a pivot pin on which a hammer is mounted, with the butt flange sufficiently flexible to allow translatory movement of the pivot pin, in combination with a metallic spring resisting such translatory movement in the absence of too vigorous depression of a piano key.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a side view of a piano action, showing certain related parts in section;

FIG. 1A is an enlarged view of a portion of FIG. 1;

FIG. 2 is a top view of the structure of FIG. 1A;

FIG. 3 is a graph illustrating reed excursion versus key impetus for a conventional piano action;

FIG. 4 is a similar graph corresponding to the piano action illustrated in FIGS. 1--2;

FIG. 5 is a side view of a piano action on a slightly larger scale than FIG. 1, showing a modification thereof; and

FIG. 6 is a view similar to FIG. 5 showing a further modification.

Turning now to the drawings in greater particularity, and first to FIG. 1, there is seen an electronic keyboard musical instrument indicated generally by the numeral 20 and including an instrument case 22 in which there is mounted a piano action 24. The action is operated by a key 26 of generally conventional design for percussively operating a vibratile reed 28 mounted on a reed bar or support structure 30. Further details as to this reed bar or support structure are not particularly important to the present application, but are to be found in Bode U.S. Pat. No. 3,183,759.

A key bed 32 is mounted in the instrument case and supports a front rail 34 and a balance rail 36. The key is conventionally pivoted on the balance rail by means including a pair of balance rail pins 38. A resilient stop 40, such as of felt, is secured to the key bed 32 inwardly of the balance rail 36 for limiting the downward movement of the inner end of key 26, and hence determining the rest position of the key. Front rail pins 42 guide the front or outer end of the key, riding in appropriate slots.

A main rail 44 is mounted within the instrument case by any suitable means, such as action brackets (not shown), and each of the individual actions 24 is fixed to the main rail 44. A hammer rail 46 is similarly supported, as is a damper rail 48. These three rails are parallel, as will be understood.

The piano action 24 includes a whip 50 which is pivotally mounted on the main rail 44 by means of a whip flange 52. A hammer butt 54 is pivotally mounted on the main rail 44 by a hammer flange 56, about which more will be said later. The hammer butt carries a hammer shank 58 which is provided with a felt tip 60. A fly or jack 62 is pivotally mounted on the whip 50 by means of a flange 64 integral with the whip. The fly 62 includes a letoff arm 66 and a nose 68 disposed in mutual right angular relation. A compression spring 70 acts between the whip 50 and the letoff arm 66 to bias the jack or fly 62 generally toward the main rail 44, whereupon the nose 68 of the fly cooperates with a felt-lined pocket 72 formed in the butt portion of the hammer butt 54. A regulating or letoff screw 74 is adjustably threaded through the hammer rail 46 to confront the upper surface of the letoff arm 66. A capstan screw 76 is threaded into the rear end of the key 66 underlying the whip 50 in the vicinity of spring 70. Felt pads 78, 80, and 82 preferably are disposed resiliently to engage the hammer butt 54, the regulating or letoff screw 74, and the capstan screw 76, respectively.

A damper release rod 84 is pivotally attached to the whip 50 on the end thereof opposite from the felt 82. The upper end of the damper release rod 84 is connected to a damper lever 86 pivotally mounted on the damper rail 48 by means of a damper lever flange 88. The damper release rod comprises a lower wooden portion and an upper headed wire portion, and is connected to the damper lever 86 by means of a fork and grommet arrangement 90. A leaf spring 98 acts between the flange 88 and the damper lever 86 to bias the felt pad 96 on the end of the damper lever into damping engagement with the reed 28.

In the playing of the piano, depression of the front end of a key 26 results in an upward movement of the capstan screw 76 against the under side of whip 50, specifically the felt pad 82. The whip 50 pivots in response to this movement, raising the fly or jack 62 whereby the nose 68 thereof presses up in the felt-lined pocket 72 of the hammer butt. Pivoting of the whip also pulls down the damper release rod 84, resulting in pivoting of the damper lever 86 and withdrawal of the felt pad 96 from engagement with the reed 28. After a certain degree of pivoting of the whip 50, the pad 80 on the letoff arm 66 of the jack or fly engages the regulating or letoff screw 74 to pivot the jack in a counterclockwise direction, whereby the nose 68 is moved from lifting position. The hammer continues its upward movement due to its own inertia, as is well known in piano dynamics, whereby the felt pad 60 of the hammer shank 58 percussively engages the lower face of the reed 28 to set the reed into decaying vibration.

The audio sound emanating directly from the reeds 28 is scarcely discernible from within the piano case 22. The vibration of the percussively actuated reeds is converted into electric oscillations which are amplified and applied to a conventional loudspeaker for conversion into audible tones. A pickup member 100 is capacitively associated with the free ends of the cantilevered reeds, the capacity between the reeds and the pickup varying in accordance with the vibrations of the reeds whereby to convert the mechanical oscillations of the reeds to electronic oscillations. The pickup member 100 comprises a comblike conductive sheet having a series of notches in which the reeds 28 respectively vibrate between the fingers alternating with the notches. The pickup member is affixed to the support structure by means such as capscrews 104, insulating bushings 106, and an elongated insulating block 108 mounted on the support structure 30. As will be observed in FIG. 1, each of the reeds 28 is mounted with its upper surface coplanar with the bottom surface of the pickup member. Each reed is electrically and mechanically connected to the support member 30 by means such as a capscrew 110 and a lock washer 112, the capscrew passing through the base of the reed and being threaded into the supporting structure 30.

The supporting structure 30 preferably is made up of a light weight metal, such as aluminum, as is the pickup member 100, while the reeds are generally made of steel. The bass reeds and some of the middle register reeds are provided with small weights 113 to produce the requisite low frequency of vibration. In order to provide the necessary mass and to allow for easy variation thereof in initial tuning of the reeds, the weights are preferably made of lead.

An additional feature of the piano action not heretofore mentioned is that the damper rail 48 is rockably mounted by means of pins 114 at its opposite ends. A lever 116 extends rearwardly from the damper rail, and has pivotally connected thereto at 118 a control rod 120. This control rod is provided with a downwardly directed spring seat 122 secured on the rod against upward movement by means such as a C-washer 124 received in a groove in the rod. A compression coil spring 126 encircles the lower end of the connecting rod 120, seating against the spring seat 122 at its upper end and seated against a washer 128 in a spring base 130 mounted on bed 32.

The lower end of the rod 120 is threaded at 132, and has detachably secured thereto an elongated nut member 134 which is secured to the inner operating member 136 of a Bowden cable 138 having an outer sheath 140. The outer sheath is fixed to a cylindrical fitting 142 which is movable up and down on the vertical arm of an L-shaped bracket 144 by means of a stud and wingnut arrangement 146. The horizontal arm of the L-shaped bracket 144 is detachably secured to the underside of the bed 32 by means of a wingnut and screw arrangement 148. The other end of the Bowden cable is secured to a foot pedal, and, upon lowering of the foot pedal, the connecting rod 120 is lowered, whereby to pivot the lever 126 and the entire damper rail 114 in a clockwise direction, and thus to raise all of the damper pads 96 from the reeds simultaneously.

Further details as to the structure heretofore described, with the exception of the hammer butt and butt flange that will be set forth hereinafter, are not necessary for an understanding of the invention. However, for those who may be interested, additional details on the action and tone generation are to be found in C.W. Andersen U.S. Pat. Nos. 2,952,179 for Electronic Piano, and C.W. Andersen 2,974,555 for Electronic Piano. Further details on the pedal structure and damper release will be found in C.W. Andersen U.S. Pat. No. 3,002,412 for Pedal Structure for Electronic Piano.

Consider for the moment that the butt flange 56 is rigid, as it is when it is made of wood-- for example, in Bode U.S. Pat. No. 3,183,757. I have established the maximum deflections of a reed from its rest position as the result of various impulses delivered to the key. For the sake of uniformity, the impulse delivered to the key was generated by a freely falling body. The magnitude of the impulse could be varied either by changing the height through which the body fell, or by varying the mass of the body, or by changing both the height and mass. It was thus established that if the mass of the falling body was approximately 200 grams or more, the maximum reed excursion was not very sensitive to changes in the mass of the falling body. Accordingly, as reported immediately hereinafter, investigation was continued with the mass maintained at a constant 200 grams, with the magnitude of the impulse delivered to the key varied by changing the height through which the body fell. A typical response curve of maximum reed excursion in inches plotted against the height of fall in inches for a 200-gram weight is shown in FIG. 3. The curve may be considered as representing a dynamic response curve for the reed over a very broad range of values in impulses to the key. Efforts were then made to establish what portion of this curve corresponds to impulses delivered to a key during normal manual playing thereof. Measurements were made, and it was found that what would be considered to be a very light touch on the key resulted in a maximum excursion of the reed at approximately 0.05 inches, as indicated at point A in FIG. 3. A medium heavy touch yielded a maximum excursion of 0.13 inches, as indicated at point B on the broken line dynamic response curve 150. What would be considered to be a heavy touch resulted in a maximum reed excursion of 0.20 inches, as indicated by point C on the dynamic response curve. The highest point plotted on the dynamic response curve is indicated at point D for a height of fall of three inches and very nearly 0.40 inches of reed excursion. It will be apparent that the portion of the dynamic response curve 150 from points A to C represents the useful response range corresponding to the ordinary dynamic response of the piano. The portion of the dynamic curve from point C to point D corresponds to a range of excessive loudness obtainable only by unreasonably heavy blows on the keys.

Stresses set up in a reed, and consequently the possibility of breakage thereof, increase as the magnitude of the reed excursion increases. It follows that reed breakage due to excessively heavy keying of the piano could be greatly reduced without impairing the normal dynamic range necessary for the satisfactory response of the piano if reed excursion could be limited to no greater than about 0.20 inches, without altering the response curve of the piano below about 0.20 inches. An idealized dynamic response curve is superimposed on the plotted dynamic response curve of FIG. 3, wherein the plotted dynamic curve portion from A to C is retained, while the solid line portion from points C to E comprises the desired idealized curve. It was ascertained that by appropriate geometric changes in the action, the reed excursion could be limited to the value of 0.20 inches, but only at the expense of depressing the entire dynamic response curve over its length, thus greatly restricting the dynamic response of the piano in a normal playing range. This, obviously, is unacceptable. Various other approaches were tried, all of which also unacceptably depressed the entire dynamic response curve, including the useful portion.

A satisfactory solution is found in changing the structure of the butt flange, as illustrated in FIGS. 1, 1A, and 2. Each butt flange 56, with particular reference to FIGS. 1A and 2, is fabricated of plastic material, polypropylene being a preferred example. The butt flanges can be individually molded, or the butt flanges can be formed as a continuous extrusion, with the individual flanges cut off from the extrusion. In the specific example shown, additional sections of material would have to be removed, if the butt flanges were formed as an extrusion.

Each butt flange has a blocklike body portion 152 having a transverse groove 154 receiving an upwardly projecting positioning rib 156 along the top of the main rail 44. A forwardly projecting portion 158 of the body is of reduced thickness, and a screw 160 passes through this reduced body portion and other parts to be mentioned hereinafter, and is threaded into the main rail to mount the butt flange thereon.

An integral web 162 extends forwardly from the blocklike body 152 beyond the reduced portion 158 almost, but not quite, to the front edge of the main rail 44. At the front of the web a vertical wall extends upwardly at 164, while an underlying vertical wall 166 extends downwardly from the web and lies against the front face of the main rail. As will be apparent, a relatively thin, flexure portion 168 of the web lies between the body portion 158 and the vertical walls 164 and 166.

Spaced apart side walls 170 extend forwardly from the vertically walls 164, 166, and a pin 172 extends therebetween about which the hammer butt 54 is pivoted. The side walls 170 are provided with upward extensions 176, and a bridge 178 connects these extensions near the top thereof.

A flat blade metallic spring 180 is held down against the top of the butt flange by an L-shaped spring retainer plate 182, the screw 160 passing through the retainer plate and through the spring. The outer end of the spring is positioned between the side wall extensions 176 and bears down against the bridge 178. In the preferred form of the invention as illustrated, the spring is a flat steel blade 0.006 inches thick, and is prestressed by virtue of the fact that the bridge 178 is higher than the top of the body 152 including the extending portion 158 thereof.

As will be apparent, the flexure area 168 of the butt flange is an area which, due to its thinness, and due to the inherent resiliency of the plastic material, is flexible. However, the leaf spring 180, under normal conditions, holds the forwardly projecting portion of the butt flange, comprising mainly the sidewalls 170, in the position shown, with the vertical wall 166 held flush against the front face of the main rail. When an upward lifting force is applied to the hammer butt by the nose 68 of the jack or fly 62 lifting in the felt pocket 92, and this upward force is not sufficient to overcome the preloading or pretension of the spring 180, then the hammer simply pivots in a normal manner. However, if the key is struck too sharply, then the upward force of the fly causes the spring 180 to yield, and the butt flange to flex in the flexure area 168, whereupon the pivot 172 moves upwardly. As a consequence of the upward motion of the forward portion of the butt flange against its elastic constraint (namely the spring 180), the angular acceleration imparted to the hammer butt by the fly is less than it would be if the butt flange were fixed. Furthermore, the upward translational motion of the butt and flange, due to the force of the fly, reduces the rotation of the fly, resulting in the fly hitting the letoff screw sooner in the keying motion than it normally would. The simultaneous effect of these two events effectively reduces the energy transferred to the reed, and thus the reed excursion.

If the force of constraint holding the butt flange to the main rail were a simple elastic force of the type F=ky, with k being the elastic constant of the constraint and y the upward displacement of the flange, the effect on the dynamic response curve of the key action would be to depress the curve over its entire length, and as noted heretofore, this is unacceptable. However, in the illustrative embodiment, the constraint holding the flange on the main rail is of the form F=F.sub.o+ ky, where F.sub.o represents the preload force on the flange due to the prestressing of the spring 180. The effect on the dynamic response curve of the action is quite different. For keying impulses below a value for which the force of the fly on the butt is less than F.sub.o, the butt flange acts as though it were rigidly fixed to the main rail, as noted heretofore, and the dynamic response curve of the action is the same as it would be for a conventional action. However, and as also noted heretofore, when the keying impulse is increased so that the force of the fly on the butt exceeds F.sub.o, an upward motion of the butt flange occurs, limiting the energy transferred to the reed.

FIG. 4 represents a graph similar to that of FIG. 3, and indeed the broken line dynamic response curve 150 is identical with that of FIG. 3. The dynamic response curve of the action in FIGS. 1, 1A, and 2 is plotted in solid lines at 184 in FIG. 4. The bottom part of the two response curves, 150 and 184, is substantially coincident from points A through C, with curve 184 having a knee approximately at point C and flattening off rather substantially thereafter, reaching at point F a maximum reed excursion of approximately 0.23 inches for a mass fall of about 1.6 inches, thereafter dropping off to point G with a reed excursion of approximately 0.18 inches for a mass fall of approximately 2.7 inches. Thus, the actual plotted graph from points C to G approximates the idealized graph from points C to E, the result being that the maximum reed excursion is held to not much greater than the desired "loud" playing point C.

A Wurlitzer electronic piano having an action such as in the aforementioned Bode U.S. Pat. No. 3,183,759 was modified to incorporate six plastic butt flanges as heretofore described in connection with FIGS. 1, 1A, and 2. Upon playing of the piano over the normal dynamic range, no significant difference in the feel or dynamic response was observed between keys having the regular and the modified (plastic butt flange) actions.

As a further check, the influence of the use of the flexible butt flanges on the breaking of reeds was investigated. A reed-life test fixture was used. Four keys with a standard electronic piano action were compared with four keys whose actions were provided with the plastic butt flanges as heretofore shown and described. Of the reeds struck by the standard action, one broke after 33 minutes, and all were broken by the end of 83 minutes. Of the four reeds struck by the modified actions incorporating the plastic butt flanges, none showed any sign of failure up to 220 minutes test time, at which time the test was terminated due to a failure of the test fixture.

It will be apparent from the foregoing that the piano action disclosed is a nonlinear one. Specifically, certain parts of the dynamic response curve are depressed to avoid reed breakage. It is contemplated that for some uses, such as in string pianos, it might be desired to increase the energy imparted to the sounding elements at high levels. With the application of principles somewhat as heretofore disclosed, a nonlinear curve could be produced in which a portion thereof would increase at more than a linear rate, and this part could be used to increase the energy at high levels. It should be noted that even a normal response curve -- as the broken line curve 150 -- is not quite a linear curve, since all piano actions have somewhat of a snubbing effect due to energy losses in the friction of moving parts, imperfect coupling of hammers to vibrating elements, etc.

A modification of the invention is illustrated in FIG. 5. In this FIG. the parts are generally similar to those heretofore shown and described, and the same numerals are used with the addition of the suffix a. The main rail 44a is identical with that previously disclosed, while the butt flange 56a is substantially identical with that previously disclosed, being made of a plastic material, polypropylene being the preferred example. The distinguishing feature in the present invention is that the hammer butt 54a is integrally molded with the butt flange from the same piece of plastic material. The hammer butt is shaped as shown, having a generally overall rectangular outline, with a central relieved area 186 having a bracing web therein, and with an upstanding reinforcing rib or web 188 along the top edge. A felt-lined pocket 92a again is provided, and a relieved section is formed behind the pocket including a web 190. The hammer butt is joined to the butt flange by a flexible integral interconnection 192 which has a small vertical dimension to promote up-and-down flexing, but which has a large horizontal dimension to prevent side-to-side displacement of the hammer.

The hammer shank 58a is made of wood with a felt covering 60a as before. The hammer butt 54a is provided with an upwardly opening, inverted T-shaped slot 194. The wooden hammer shank is received in the stem of the slot, and epoxy cement is inserted in the crossbar. The epoxy cement adheres well to the wood, and securely locks the hammer shank in place in the T-shaped slot in the butt. The felt lining of the pocket 92a is not subjected to the same type of stresses as is the connection between the hammer shank and butt, and it has been found that a rubber or latex contact cement adequately secures the felt permanently in place.

Operation of the piano action as illustrated in FIG. 5 is the same as that heretofore shown and described, except that the pivot pin has been eliminated and the hammer butt pivots relative to the butt flange by flexing of the flexible section 192. Meanwhile, a great deal of hand labor and machining of parts has been eliminated, along with the elimination of the possibility of improper insertion of the pivot pin.

A further embodiment of the invention is illustrated in FIG. 6. The hammer butt is similar to that of FIG. 5, and similar parts again are identified by the use of similar numerals, this time with the addition of the suffix b. The hammer butt is integral with the butt flange at a thin flexible section 192b. In this instance, the butt flange 56b is more nearly akin to a conventional one, and has no provision for flexing in the event of overenthusiastic playing of the piano. The butt flange is simply a relatively flat rectangular block molded integral with the hammer shank, and having a transverse slot 154b on the bottom thereof for receipt of the positioning rib 156b. A screw 160b, preferably with a washer or reinforcing flange or holddown plate under the head thereof is passed through a hole in the butt flange and is threaded into the main rail 44a. Operation is the same as that of a conventional piano action, except that pivoting is at the relatively thin flexure location 192b, rather than at a pivot pin.

In the present application I have disclosed various plastic piano action parts. In one form of the invention, the plastic part comprises a butt flange constructed to allow yielding of the pivot point in the event too much force is imposed on a key, thereby limiting the transfer of energy to the vibrating element. In another form of the invention the hammer butt also is molded of plastic material, and is formed integral with the butt flange, being connected thereto by a flexural portion with attendant elimination of the pivot pin. In yet another form of the invention the butt flange is of more nearly conventional construction, but is molded of plastic material integral with the plastic hammer butt, being joined thereto by a narrow section of flexible material. The specific examples of the invention as herein shown and described are by way of illustration, and various changes will no doubt occur to those skilled in the art, and are to be understood as forming a part of the present invention insofar as they fall within the spirit and scope of the appended claims.

* * * * *

Current U.S. Class:	84/237 ; 84/251
Current International Class:	G10C 3/00 (20060101); G10C 3/22 (20060101); G10c 003/18 ()
Field of Search:	84/236,237,238 29/149.5NM 84/251,252,404,405,1.13,1.14