WO1993019454A1

WO1993019454A1 - Keyboard mechanism

Info

Publication number: WO1993019454A1
Application number: PCT/GB1993/000559
Authority: WO
Inventors: Gabor Bartos
Original assignee: Gabor Bartos
Priority date: 1992-03-19
Filing date: 1993-03-18
Publication date: 1993-09-30
Also published as: EP0631684A1; AU3760693A; GB9205956D0

Abstract

There is disclosed a harpsichord mechanism for a piano having strings (13) each with an associated key (11), hammer (12) and damper (17), the damper (17) being lifted off the string (13) by depression of the key (11), said mechanism comprising, for each string (13), a plectrum-holding jack (24) movable with respect to the string (13) so that the plectrum (25) plucks the string (13) while the damper (17) is lifted off the string (13) by depression of the key (11).

Description

KEYBOARDMECHANISM

This invention relates to a keyboard mechanism.

A harpsichord is in many regards similar to a piano, but has a plucking action as opposed to a striking action which causes the strings to emit a different kind of sound. There are however other, more subtle, differences which affect the construction and the sound of the instruments. The harpsichord is very- much a serious musician's instrument, whereas the piano may perhaps be termed as a general purpose instrument with, of course, a sound musicological history through a more recent development. In short, the instruments are very different despite the obvious similarities.^'

The present invention enables a piano inter alia, however, to perform the double role.

There is, in view of the above considerations, some prejudice against the attempt, of course, it being thought among serious musicians that no piano could even be made to sound like any actual harpsichord. Then there is the problem, once the idea is conceived and accepted, of how to do it, how to modify the hammer action of a piano so as to emulate, however imperfectly, a harpsichord action to produce, however imperfectly again, a harpsichord sound. The present invention provides inter alia a harpsichord mechanism for a piano which, overcoming the prejudice, solves the practical problems.

The invention comprises in one aspect a harpsichord mechanism for a piano having strings each with an associated key, hammer and damper, the damper being lifted off the string by depression of the key, said mechanism comprising, for each string, a plectrum- holding jack movable with respect to the string so that the plectrum plucks the string while the damper is lifted off the string by depression of the key.

The plectrum may pluck the string adjacent the damper. The jack may be moved by a damper-lifter.

The mechanism may comprise a jack-rack having guides for the jacks with a jack return arrangement. Each guide may form a yoke containing a jack return spring; each jack may have a spring-engaging clip captive within the yoke. However, the jack return arrangement may operate by gravity, so that a conventional harpsichord jack may be used.

The mechanism may comprise a hammer disabling arrangement, which may comprise a wedge interposable between elements of the hammer-operating lever arrange- ment to cause the hammer to stop short of the string when the key is depressed. The hammer-operating lever arrangement may be of the type which includes a backcheck arrangement which constrains hammer movement and the hammer disabling arrangement may then cause the backcheck arrangement to stop the hammer short of the string.

The hammer disabling arrangement and the rest of the harpsichord mechanism may be interconnected so that the hammers are disabled when the harpsichord mechanism is engaged, but the hammer disabling mechanism may also be arranged to operate independently of the harpischord mechanism.

Indeed, the hammer disabling mechanism may be fitted to a piano without the harpsichord mechanism to provide, in another aspect of the invention, a silent, practice keyboard, while a piano fitted with the hammer disabling mechanism may also have an electric or electronic piano, organ or synthesiser arrangement which may be operated through the piano keyboard with or without the hammers being disabled by the disabling mechanism.

The harpischord mechanism may itself have a disabling arrangement so that while in situ in a piano it may be brought into action or disabled as desired. When the mechanism is operative, the jack may be moved by a damper lifter via a pivoted rod, the rod being pivotable out of the way of the damper lifter.

The piano may be of the kind in which the hammers are shiftable with respect to the strings by a soft pedal so that, where each string is multiple, the hammer strikes only one string of the multiple set. The plectrum of the harpischord mechanism may then be arranged simultaneously to pluck an unstruck string of the multiple set. This gives an unusual effect of a piano and a harpsichord being played together.

Embodiments of a keyboard mechanism according tc the invention will now be described with reference to the accompanying drawings, in which :-

Figure 1 is a side elevation of a piano action showing an added harpsichord mechanism;

Figure 2 is a view in the direction of arrow 2 on Figure 1;

Figure 3 is a view in the direction of arrow 3 on Figure 1; Figure 4 is a view on arrow 4 of Figure 1;

Figure 5 is a side elevation like Figure 1 of a second embodiment;

Figure 6 is a view like Figure 2 of the second embodiment;

Figure 7 is a side elevation of an upright piano action with added harpsichord mechanism;

Figure 8 is a plan view of part of the action^* of Figure 7

and Figure 9 is a side elevation of another embodiment.

Figure 1 illustrates, in fine line, a conven¬ tional grand piano action. The keyboard, not shown, is to the right. Element 11 is part of a key. When the key is depressed to play a note, element 11, which is pivoted somewhere to the right of the drawing, lifts.

By a complex arrangement of levers, the upward movement of element 11 flicks the hammer 12 upwardly towards the string 13. It will be seen that the shaft 14 of the hammer 12 is not tied to the element 11, rather it is pushed upwardly and allowed to fall back freely. This mechanism has been developed over many years to enable the pianist, by virtue of the way the keys are struck, or "touch", to produce sounds having a range of loudness values and qualities. The mechanism is carried on cross beams 15 mounted on the frame 16 of the piano.

The string 13 is normally damped by felt damper elements 17 so 'that it will produce no or hardly any sound. At the extreme left of the element 11 is a bearing 18 which raises a lever 19 which lifts the damper elements 17 via a wire rod 21. Thus the elements 17 are lifted from the string 13 whenever the key is struck so that when the hammer 12 strikes the string 13, a note is produced.

All the elements 17 are lifted from all the strings 13 by the sustaining pedal (not shown) which raises all the levers 19 by means of a beam 22 which is loaded by a spring 23 at each end.

The harpsichord mechanism is shown in bolder line principally in Figures 1 and 2, Figures 3 and 4 showing details. The mechanism comprises, for each string 13, a jack 24 which holds a plectrum 25 - a small piece of plastic, which substitutes here for the "quill" of the conventional harpsichord.

It will be seen from Figure 2 that each string 13 is in fact a set of three strings. The jacks 24 are situated so that as they are lifted, the plectrum plucks just one of the three strings.

The jacks 24 are carried in a jack or guides 24a secured directly to a cross member 26 of the piano, each guide 24a forming a yoke containing a jack return spring 27 which acts between the top of the yoke and a clip 28 which snaps from the side into a groove in the jack 24.

A rod 29 is pivoted to the jack so that it -can move between the solid line, operative position of Figure 1 and the broken line, inoperative position. The jack 24 is lifted against the loading of return spring 27, by a jack lifter 31 acting on the rod 29. The jack lifter 31, which is shown- in more detail in Figure 4, is simply a small casting or moulding with a soft bearing pad 31a which is clamped by a set screw 32 to the wire rod 21 that lifts the damper elements 17.

Thus, as the piano key is depressed, the lever 19 simultaneously lifts the damper elements 17 and causes the plectrum 25 to pluck the string 13. Because the damper elements 17 are lifted from the string, the plucking action causes the string to vibrate with a characteristic harpsichord sound. When the key is released, the damper elements 17 fall on to the string again (assisted now by the return spring 27) so that even though the plectrum 25 again contracts the string on its way down it cannot set it in vibration.

With the mechanism in the operative, solid line position, it will be recognized that operating the sustaining pedal will have the effect of plucking every string simultaneously in a single fortissimo. No doubt some avant-garde composer will incorporate this into a concerto for the instrument.

The mechanism is rendered inoperative, however, by swinging all of the rods 29 into the broken line position of Figure 1. This is achieved by means of a cross bar 33 which carries screws 34 which loosely engage slots 35 in the rods 29 so that each rod 29 can freely move up and down in the operative position independently of the others. In the operative, broken line position, of course, the rods are not lifted by the levers 19. The dampers 17 are of course still lifted both by key operation and by the sustaining pedal. At the right hand side of Figure 1, the bolder lines illustrate a mechanism which disables the hammer action. Its operative, i.e. disabling position is in solid line, its inoperative position is in broken line.

This disabling mechanism comprises a wedge 41 which is carried on a pivoted bracket 42, also seen in Figure 3. The bracket 42 extends right across the piano and one wedge 41 is provided for each key. The wedges 41 interpose, in the operative position, between elements of the hammer action to cause the hammer 12 to be pulled up short of the string 13 by the backcheck arrangement incorporated in the action.

In another arrangement illustrated in 'Figure 9, the wedge 41 is replaced by a spring 91, the springs being mounted on a mounting rack 92 on which they can be pivoted between operative and inoperative positions - this arrangement can give an even more natural response than can the wedge 41 when operative, so that the pianist is even less likely to notice any change in touch.

The bracket 42 is connected by a wire, omitted for clarity's sake, to the cross bar 33 so that they move together. The bracket 42 is readily accessible from the front of the piano, i.e. from the right hand side of Figure 1, so that the conversion from piano to harpsichord and back can be made easily by the pianist without leaving the keyboard.

While this arrangement enables the instrument to be played either as a piano or as a harpsichord, it is also possible to utilise another feature of many grand pianos, which is that the soft pedal shifts the action laterally relative to the strings so that the hammers, instead of hitting all three strings of the set, hit only one of them. If, in this mode, the harpsichord mechanism operates on another of the strings of the set, an unusual combined piano and harpsichord sound will be made which may also appeal to modern composers.

Figures 5 and 6 illustrate an embodiment in which the jacks 24 of Figures 1 and 2 are replaced by more conventionally fashioned jacks 54 which are not spring loaded but rely on their weight to return them once the key is released. Instead of the rods 29 of Figures 1 and 2 being pivoted to the jack 24, the entire jack 54 of Figures 5 and 6 is movable by cross bar 53 which corresponds to cross bar 33 of Figures 1 and 2 - this can move all the jacks 54 as shown in Figure 5 away from the end of the damper lifter 19a - the embodiment of Figures 1 and 2 required a special jack lifter 31, which is not needed in this second embodiment provided there is enough room on top of the damper lifter 19a - towards the keyboard or, as shown in Figure 6, laterally so that their lower ends lie between adjacent damper lifters 19.

Figures 7 and 8 illustrate another action in the context of an upright piano in which a bell crank 7.1 fixed to the hammer rest rail 72 is acted on by a first wire 73 from the lever 74. The bell crank 71 is biassed by a spring 71a to the illustrated position and acts on a second wire 75 which is attached the plectrum 76. Movement of the second wire 75 pivots the plectrum 76 about an axis parallel to the string 77, the pivot being located in a rail 78 running along the piano in front of or behind the strings 77 as may be convenient. The pivoted position is shown in dashed line in Figure 8.

The wire 75 has threaded ends engaging end connectors 75a,75b enabling fine adjustment of the effective length of the wire 75.

The embodiments described with reference to the drawings are exemplary only and may be adapted for different makes sizes and kinds of piano, for example the full concert grand, the boudoir grand or the baby grand, for upright pianos, for conventional acoustic or for electric pianos. The mechanism may be provided as a retrofit to existing pianos, or may be designed into a new dual function instrument, in which case the selection of piano or harpischord can be made by a purpose-built "stop" on the keyboard and additional stops can be provided to further alter the sound - the pitch and/or timbre - of the strings in the harpischord mode, as is done on conventional such instruments.

The instrument may be readily adapted to fulfill yet a further function, namely a soundless practice key¬ board by enabling the hammer-disabling arrangement to be used without engaging the harpsichord mechanism. Indeed, the hammer disabling mechanism may be fitted on its own without the harpsichord mechanism for this purpose.

Further, the hammer disabling mechanism can be used in connection with an lectric or electronic arrangement in which the keyboard has electrical switch or actuator means to operate an electric or electronic piano or organ or synthesiser which may be operable with or without the. hammers striking the piano strings and may be rendered inactive so that the piano can be played with or without the electric or electronic equipment.

Claims

1. A harpsichord mechanism for a piano having strings each with an associated key, hammer and damper, the damper being lifted off the string by depression of the key, said mechanism comprising, for each string, a plectrum-holding jack movable with respect to the string so that the plectrum plucks the string while the damper is lifted off the string by depression of the key.

2. A mechanism according to claim 1, in which the plectrum plucks the string adjacent the damper.

3. A mechanism according to claim 1, in which the jack is moved by a damper-lifter.

4. A mechanism according to claim 1, comprising a jack rack having guides for the jacks each guide forming a yoke containing a jack return spring.

5. A mechanism according to claim 4, in which each jack has a spring-engaging" clip captive within the yoke.

6. A mechanism according to claim 1, comprising a hammer disabling arrangement.

7 . A mechansim according to claim 6, in which said hammer disabling arrangement comprises a wedge interpos- able between elements of the hammer-operating lever arrangement to cause the hammer to stop short of the string when the key is depressed.

8. A mechanism according to claim 6, in which the hammer-operating lever arrangement includes a backcheck arrangement which ^*"constrains hammer movement and the hammer disabling arrangement causes the backcheck arrangement to stop the hammer short of the string.

9. A mechanism according to claim 6, in which the hammer disabling arrangement and the rest of the harpsichord mechanism are interconnected so that the hammers are disabled when the harpsichord mechanism is engaged.

10. A mechanism according to claim 6, in which the hammer disabling mechanism is operable independently of the harpsichord mechanism.

11. A mechanism according to claim 1, having a disabling arrangement.

12. A mechanism according to claim 11, in which the jack is, when the mechanism is operative, moved by a damper-lifter via a pivoted rod, and the rod is pivotable out of the way of the damper-lifter.

13. A mechanism according to claim 1, in which the hammers are shiftable with respect to the strings by a soft pedal so that, where each string is multiple, the hammer strikes only one string of the multiple set, and in which the plectrum for each such string can simultan¬ eously pluck an unstruck string of the multiple set.