EP0022817A1

EP0022817A1 - Piano-action keyboard

Info

Publication number: EP0022817A1
Application number: EP80900203A
Authority: EP
Inventors: Philip V.W. Dodds; Mark V. Smith
Original assignee: Arp Instruments Inc
Current assignee: Arp Instruments Inc
Priority date: 1979-01-02
Filing date: 1980-07-14
Publication date: 1981-01-28
Also published as: EP0022817A4; WO1980001427A1; IT7928457A0; DE2953460A1; GB2049255A; JPS56500055A; IT1127777B

Abstract

Un clavier a action de piano pour un instrument de musique electronique ou similaire balaie un actionneur de commutateur (39) par l'intermediaire de contacts de commutation (78, 88) d'une plaque a circuit imprime (60) pour produire des signaux indicatifs de la position et du mouvement d'une touche lorsqu'elle est actionnee. Le clavier procure une reelle sensation de toucher de piano au moyen d'une rangee de touches enfoncables (12) et de bras (24) associes. Chaque bras supporte un actionneur de commutateur (26) ou similaire, avec une force de transmission variant aux differents stades de l'enfoncement de la touche correspondante, la combinaison d'assemblage electrique-mecanique permettant une reponse a1a fois pour ce qui est des resultats et de la reaction cinesthesique simulant une action manuelle du piano.A piano action keyboard for an electronic musical instrument or the like sweeps a switch actuator (39) through switch contacts (78, 88) of a printed circuit board (60) to produce indicative signals the position and movement of a key when it is pressed. The keyboard gives a real feeling of piano touch by means of a row of push-in keys (12) and associated arms (24). Each arm supports a switch actuator (26) or the like, with a transmission force varying at the different stages of depressing the corresponding key, the combination of electrical-mechanical assembly allowing a response once in terms of results. and kinesthetic reaction simulating a manual action of the piano.

Description

PIANO-ACTION KEYBOARD BACKGROUND OF THE INVENTION

The invention relates to piano-action keyboards and, more particularl _■ to a piano.- ction keyboard- for an electronic musical instrument and is characterized by uniquely providing realistic piano feel and practicality of high volume manufacture and utilization having regard to considerations of reliability, effectiveness and cost.

Musical instruments frequently use keyboards for determining sounds to be played. Two common kinds of key¬ boards are organ-type keyboards and piano-type keyboards. An organ-type keyboard has a plurality of two-state switches, each controlling a specified pitch. - Each switch controls a tone source which generates a signal whose duration is determined by the length of time its corresponding key re¬ mains depressed. In contrast, a piano-action keyboard pro¬ vides, in addition to pitch selection, a range of expression generally characterized by a complex function of volume, harmonic structure and envelope which is dependent on the speed and force with which the key is struck. At the same time, a characteristic kinesthetic feedback is provided. The "feel" of a keyboard is a characteristic that is gen¬ erally of great importance to the player. Organ-type key¬ boards have a comparatively stiff, spongy feel, while piano-action keyboards typically have a lighter, more com¬ pliant feel. Commonly available electronic keyboard in¬ struments, typically have a feel more nearly characteristic of an organ, and this is a significant drawback when the instrument is used to simulate piano-type instruments, since the player is frequently conditioned by prior training to prefer the piano-action feel.

Conventional piano actions are quite complex in nature and their^' "feel" is determined by the interaction of a large number of moving parts. Careful adjustment of these actions is required during the manufacturing process and this adds to thier cost. Further adjustments may be required during continued use, and this is an inconvenience, as well as a possible further expense, to the owner.

Accordingly, it is an important object of the present invention to provide an improved piano-action key¬ board for an electronic music instrument, such as a poly¬ phonic synthesizer, avoiding the difficulties of the above referred.to prior art.

SUMMARY OF THE INVENTION

In accordance with the present invention, a piano- action keyboard, usable for operation of electronic musical instruments (including pianos and in other contexts pre¬ senting equivalent needs in whole or in part) , is formed from a 1 linear array of depressable elongated playing keys, each pivotally mounted on a supporting base, and an array of elongated arms pivotally mounted on the base. Each arm has a forward end above and adjacent to a rear end of the key (keys and arms being arranged with substantially parallel elongation) . In response to depression of a front end of any key to pivot it, the corresponding arm is moved by a force transmitted at an interface with the key. An electric signal means for the instrument includes fixed electrical circuit components behind the arms and compliant mechanical arms extending from the back of each arm to wipe across the fixed structure as the arm moves and thereby provide electrical signals indicative of the position of the key and velocity of key depression.

The said interface between key and arm of each pair is arranged to provide a varying geometric resolution of force transmitted from key to arm at different stages of key depression. At initial key depression, the component is lower and Fx component is higher compared respectively to Fy and Fx components at a later stage of key depression where y is direction of application of force (and of the arc path [tangent] of travel of the striking point between key and arm) and x is orthogonal to y. In short, the apparent resistance of the key arm combination to striking decreases

O PI at a later stage of key depression.

Each such arm has a weight distribution about its pivotal axis which acts in opposition to the force trans¬ mitted from a depressed key but continues inertial movement of the arm after key strike. Fixed stops intercept the heavily weighted arm portions. Restoring springs loaded by arm movement help return the arms to at-rest positions after key release and usually maintain^' key-arm contact. The spring force is overcome by the inertia of weight distri¬ bution to allow a sudden hard key strike to throw the arm into its extreme position beyond its key contact range (established by a key stop) .

The spring arm carrying the roller is driven by the mechanism to sweep the roller across the switch element with a substantially constant normal force. The force is primarily tangential rather than normal to the switch element's compliant surface as the roller moves along it, such tangential force being only of sufficient magnitude to overcome friction and the normal force component being only as much as necessary to deform the contact layer. But the arrangement uniquely provides negligible <effective reaction force to the actuating mechanism. Such reaction force as is transmitted back into the main actuating piano action linkage is negligible in relation to the forces in¬ volved in key strike and restoration of the linkage to its normal position.

The pattern of interaction of the movable roller and switching element tends to remain stable over a period of time, thus providing a consistent feel to the piano player who will be striking keys and expecting the same response to a given combination of speed and force elements in a key strike motion.

The compliant surface of the elongated switching element is placed at an angle of 50-80° to horizontal, in a plus or a minus direction and the actuating mechanism has at least one link operating about a horizontal axis perpen¬ dicular from and substantially spaced from the traverse line along a switching element so that a substantially flat (small segment along a large radius) range of movement of significant length, half an inch or more, preferably over an inch, is provided for the roller carried on a spring at the working end of the actuating mechanism. This arrangement provides a high tolerance of spacing of diff¬ erent active and inactive portions of the switching element, while maintaining substantially constant normal force applied by the wheel, consistent with a practical actuating mechanism.

These and other objects, features and advantages of the invention will be apparent from the following de¬ tailed description with reference therein to the accompany¬ ing drawing in which:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view of a single key arm/ electrical signal output device combination of a keyboard and typical of all such combinations in the keyboard linear array and FIG. 2 is a corresponding top view (a dash line alternate position is also seen) ;

FIGS. 3A-3C are simplified force diagrams showing the general geometric resolution of forces transmitted from key to arm at two positions of the key and the nature of the key arm interface for another embodiment shown in FIG. 3D;

FIGS. 4A-4G are planar views of a number of al¬ ternative embodiments of the switchboard switch elements in which FIG. 4A shows a contact configuration in which two discrete pulses are generated as the switch actuator contact either element, FIG 4B shows a configuration in which a pulse train is generated on a single output line, and FIG. 4C shows a configuration having an added upper and lower contact; FIG. 5 shows a detail of the switchboard and a simple utilization circuit for measurement of arm's velocity;

FIGS. 6A-6C are side, front and top .views of a coupling between the mechanism and electrical switching element in accordance with a preferred embodiment of the invention and FIG. 6D shows a front view of a variant em¬ bodiment. FIGS. 6E-6H show further variants.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring specifically now to FIGS. 1 and 2, an elongated key 10 having a playing end 12 and a front pun¬ ching 14 mounted thereunder is mounted for depression by a player. The key 10 rotates about a rail 16 and has a back cloth 18 mounted under a back end 20 of the key. Mounted adjacent the back end 20 of the key is the flange 22 supported from a fixed base and on which flange an arm 24 is mounted. A jack 26 may extend downward from the arm or upward from the key as shown (preferably the latter) . The arm is pivotally mounted by means of a fixed pivot 28. A key pad 30 mounted on the rear end 20 of the arms meets the upper surface 32 of the jack 26. The flange 22 supports one end of a spring 34 which extends along the arm (rear) end remote from the flange 22. A spring arm 38 is mounted on the rear arm end, extends beyond the end of the hammer arm 24 and has a roller 39 mounted on its remote end. A switchboard 40 carrying an upper pressure sensitive layer 42 upon which the roller 39 presses is mounted on a lower frame 44. An upper frame 45 carries an arm stop 46 which limits the travel of the arm 24.

When the palying end 12 of the key 10 is depressed, the key pivots about the rail 16 and lifts jack 26^" to thereby rotate the arm 24 about pivot 28. This causes the roller 39 to wipe downwardly across the switchboard in direct response to the motion of the arm 24. Although the weight 36 may contact the arm stop 46 at maximum travel, key travel is limited by the key contacting the front punching 14 when depressed.

FIGS. 3A, 3B, 3C show resolution of forces for the FIG. 3D embodiment of the invention differing from that of FIG. 1 in that a jack 26' extends from the arm to the key and meets it at an interface 26". Two intersecting planes PI and P2 of the jack end are engaged by a key pad 30' on key 10'. Plane PI is engaged when the key is at rest (FIG. 3A) . Initial depression (FIG. 3A through 3B positions) provides a resolution of transmitted force F into Fx and Fy components (where y is direction of move¬ ment of 30' and x is orthogonal to y) that has a high Fx and low Fy compared to a later stage of key depression and resultant arm movement (FIG. 3B through 3C positions) where pad 30 engages plane P2 and Fx is much lower and Fy higher as resolved geometric components of transmitted force F.

Going back to FIG. 1, the same qualitative effects are achieved through the curved (spherically rounded) screw head end 32 of jack 26 on the key but with smoother transition from stage to stage.

As shown in FIG. 3A, the lower surface 32 of the jack 26' comprises two intersecting planar faces PI and 52. Initially, the jack fact PI rests flat on the key pad 30'. As the key is depressed, the remote end of the key rises off the backcloth 18 and the jack fact PI slides in direction "a" relative to the key pad. As the rear end of the key and the front end of the arm move upward, the orientation of the jack 26 rotates with respect to the key and the Fx component decreases. Upon release of a key, the inertial force of the weight 36 and the torsional force of the psring 34 pushing against the arm, act to restore the entire mechanism to its "rest" position as shown in FIG. 3A. The spring develops a relatively small, fast acting force overcoming the inherent limitations of an inertial force such as the arm weight. Through elimina¬ ting the escapement mechanism of a traditional piano action

OMP 7

and through the increase in Fx as the 'key is released and the front end of the arm descends, contact can be maintained between the key and key bounce is reduced. This immediate restorative force adds responsiveness and quick restrike capability characteristic of a good piano action.

The added weight 36 (or an equivalent weight distribution within the arm) greatly contributes to the desired piano-action feel by providing an inertial force to the arm 24 which continues the motion of the arm in response to a brief but forceful key depression. This contributes to achieving the response of a grand piano action without the complexity of such an action. Control over wide -dynamic range is provided by the-above features.

Unlike a conventional piano action in which a hammer mechanism actually strikes a string to cause onset of a note, the piano-action keyboard for an electronic musical instrument need only impart a characteristic piano-action feel and response to the keys. Mechanically, this allows it to be greatly simplified, but electronically it must interface with circuitry which controls and generates the parameters necessary for operation of an electronic music instrument, (e.g., a synthesizer). This electromechanical interface is preferably provided by the switch elements. Any mechanical friction existent in the electromechanical interface will be "reflected" in the feel of the key action. Since it is an object of the present invention to provide a realistic key feel, and response, it is important that such friction be minimized.

One preferred form of the switch elements com¬ prises a spring arm 38 and roller 39 mounted at the end of the arm remote from the pivoted end and a plurality of switch elements mounted on a switchboard 40 positioned tangential to the flight of the spring arm so as to remain in contact with the roller 39 through the entire arc which the arm 24 travels. The sliding friction which would normally exist if the spring arm 38 directly wiped the

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/,- WIIPPOO ..v switchboard 40 is convered to rolling friction by roller 39. This roller reduces the overall drag that would otherwise exist in the keyboard response and substantially improves the restrike characteristics. Switch elements within the switchboard 36 within this arc are utilized to implement a number of alternative embodiments for position and motion measuremen s.

FIGS. 4A-4C are planar views of various forms of contact boards useful in the invention. A preferred em¬ bodiment of the switchboard contact elements is shown in FIG. 4A and comprises a narrow first contact 54 and a second contact 56 spaced from the first contact, both mounted on a substrate 58; the roller initially (i.e. , at it rest position) contacts the PC board 58 at the position indicated by line 60. In its rest position, as the spring arm falls upon depression of a key, the roller crosses contact 54, developing an initial narrow pulse 62. It then passes .across non-contact area 64 and finally touches contact 56 which develops a pulse 66 which remains "on" as long as the spring arm stays in the up position corresponding to the "key depressed" state. Arrows S and R indicate roller 39 motions on key strike and release. This configuration can provide significant information when* interfaced with appropriate electronic circuitry. Since the first contact 54 is spaced below the rest position 60 of the spring arm, initial accelerations required to overcome gravity and mechanism friction have decreased by the time the spring arm crosses the first contact. The time between the falling edge of the first contact pulse 62 and the onset of the second cntact pulse 66 is indicative of the velocity of key/spring arm travel. By attenuating initial irregularities in spring arm velocity, the measurement of this time becomes more re- peatable for successive keystrokes. Partial release of a key brings the spring arm above the second contact thereby

OMP WIP indicating key release. If the spring arm is allowed to at least touch the first contact area 54 before it again falls (due to key depression) to touch the second contact 56, the piano-action "restrike" characteristic is .cloaely simulated.

An alternative contact scheme is shown in FIG. 4B. As the spring arm travels across the contact board 68, a series of pulses is generated. Iterative time measure¬ ments taken on this pulse then give "incremental," as well as average, velocity. FIG. 4C is a second pulse train con¬ tact layout utilizing two additional contacts. An upper contact 72 remains "on" (73) until key depression begins. A pulse train^"74 is then generated as"described previously. A lower contact 76 then goes "on" (77) as the key reaches its maximum travel. Using this contact pattern, discrete events can be triggered at the beginning and end of key depression in. addition to generating signals indicative of key velocity. For example, one of the intermediate pulses may be used to trigger a modifier, such as a sample-hold circuit for varying timbre. Also the final pulse, corresponding to the key being held down, can be used to control an "on-off" instrumental effect which is independent of key velocity. This can be useful in achieving a "layered" musical effect, with an "orchestral quality."

Since a plurality of algorithms exist for measurement of key strike velocity, it is important that an improved piano-action for an electronic musical instrument have an electro-mechanical interface flexible enough to meet the varying requirements of these different methods.

The preferred embodiment of the "contact" pre¬ viously described is a modified version of a commercially available "membrane" or "touch" type switch. FIG. 5 is a cross sectional elevation view of the switchboard of FIG. 4A. Two conductive pads 78 and 80 are mounted on an insulating substrate 82. Spacers 84, 86 are mounted to

O PI_ „IPϊO^., physically separate the conductive pads 78, 80 from the lower conductive surface 88 of the flexible switch plate 90. In operation, as the roller passes over area 54, the switch plate 90 flexes downward causing conductive layer 88 to contact pad 78, thereby creating a closed circuit. When the roller is over area 64, no contact is made due to the insulating spacer 86. Contact is made between the pad 80 and the conductive layer 88 when the roller depresses the switch plate 90 over area 56. A voltage source 92 is connected to the conductive layer 88 thereby generating voltage changes as the pads 78 and 80 are contacted.

An embodiment of utilization circuitry is also shown in FIG. 5. The positive-going edge of the pulse 62 resets a counter 94 to its maximum value. The negative- going edge of pulse 62 enables a high frequency clock 96 which begins decrementing the value in the counter.. This decrementing continues until the positive-going edges of pulse 66 disables the clock thereby effectively "freezing" the final value in the counter. This final value is stored and used as a relative amplitude voltage to control an electronic musical instrument. The lower . the velocity of key depression, the longer the time between first * contact pulse and second cntact pulse, and correspondingly, the smaller the final value output. Should the time between first and second pulses be long enough to allow complete decay from the maximum value, the output would be zero. This corresponds to a very slow key depression and, as in a true piano action, there exists a lower key strike thres¬ hold below which no sound is generated.

In an alternative optional embodiment, pro¬ vision may be made to have some non-zero value of output corresponding to a very slow key depression. Although this is not characteristic of the response of a true piano action, it would be of considerable aid to musicians attempting to achieve an extremely soft "pianissimo" effect without the

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/._ WI1P1. OU problem of some notes not sounding at all.

Variations from the above described preferred embodiments, meeting one or more of the objects of the in¬ vention and within the broadest scope-thereof include, without limitation, capacitance or resistance change transducers in lieu of normally on or normally off switches; optical-mechanical pickups in lieu of electromechanical pickups; electromagnetic or magnetic pickups, or Hall effect pickups in lieu of electromechanical pickups; multiple arms associated with each key (i.e., addition of intermediate arms between key and switch-carrying arm) ; and usage of the keyboards hereof in non-musical applications (e.g., graphics, computer or communication machine consoles) .

Referring to the exemplary signal means shown in FIGS. 3D and 1-2 (the latter being preferred) it will be appreciated that various rolling or sliding arrangmeents can be made in various geometries to implement the objects of the invention.

Expanded side, front and top views of spring 38 and roller 39 are shown in FIGS. 6A-6C respectively and a front view of a variant embodiment of this coupling is shown in FIG. 6D. The roller 39 is mounted on trunnions 391 which are supported by bent ears 381 located at the end of a sheet spring element 38 of vee-bent form. The inte¬ gral nature of spring element 38 avoids the need to accommo¬ date tolerances in mating parts. While two ears are pro¬ vided straddling a roller in FIG. 6A-6C, the arrangement can be as simple as an end twist to form a single ear 38D1 (at the end of a spring element 38D which is not of vee-bent form but gets its resilience from a simple curvature or deflecting arrangement with respect to the switch element) . The FIG. 6A-6C embodiment is preferred in relation to the FIG. 6D embodiment. A bent end portion of the spring 38, 380, is mateable to the actuating arm of the actuating mechanism by bolting thereto (by a bolt or other fastener passed 12

through a hole 379 in the tab 380) . Typical dimensions of the left arm L and right arm R of the veeObent spring 38 are .844 and 1.00 inches respectively and a typical angle A is 15°. The roller 39 is typically a one-quarter inch diameter by .063 inch wide cylindrical element.

FIG. 6E shows a spring element 38E of wire form (typically .023 inch diameter brass spring wire) which can be fastened by a screw as indicated in exploded form - to arm 24 and used to hold a roller 39E with a dished edge carrying a rubber (or plastic 0-ring 39E1. The wire passes through a central hole 39E' in the wheel and may have loose ends there or may be fastened into a closed loop (with the fastening point between two wire ends at any point along the wire length. FIG. 6F shows a variant of the FIG. 6E embodiment wherein a wire 38F of paper dip form wherein end 38F' passes through the hole in the wheel 39E (FIG. 6E) and end portions 38F" are twisted (and excess length portions thereof may be cut off) . The legs 38L can ride against wheel sides to restrain twisting of the wheel. FIGS. 6G and 6H show that the switch 42 acute angle face can be at positive or negative acute angles and that the bend of spring arm 38 (of any of the variant forms above) can be upwards or downwards from a basic at rest position AR of the spring arm.

- ^*UB.E

O P

Claims

13CLAIMS

1. A piano-action keyboard for an electronic musical instrument comprising, a plurality of elongated keys, a supporting base, each of said keys being pivotally mounted on said supporting base, a plurality of hammer-like arms pivotally mounted on said base, each arm being adjacent one end of a key and arranged so that when the key is pivoted, a driving force is imparted to the adjacent arm by direct striking of the arm in a strike region thereof by the key, each arm having a heavily weighted, portion relating to other portions thereof, electrical signal means comprising an actuating com¬ ponent mounted on each said pivoted-arm and plural portions of said signal means each of which is responsive to movement of one said arm to generate an electrical signal as the associated arm moves including response to rate of movement of the arm and to travel of the arm, a spring means mounted on said base and connected to each arm to apply to each such arm, when loaded by a corresponding key strike and resultant transmission of force to the arm, a restoring force in opposition to the force so applied, means pivotally mounting each such arm, the said strike region and distribution of weight of each arm being arranged so that the weight distribution applies an inertial force (as an unbalanced net weight) on said arm in opposition to the force applied to the arm by the key, the combination of spring and weight affording a kinesthetic feedback to the keys simulating that of a manual piano.

2. A piano-action keyboard according to claim 1 which further comprises, an upper frame extending over and above said 14

pivoted arms, and pivoted arm stop means on said upper frame extendi downward for contact by said heavily weighted portion of sai arm at a limit of travel position thereof.

3. A piano-action keyboard according to claim 2 i which said spring is so selected as to apply to said arm a force less than the inertial force of said weight distri¬ bution.

4. A piano-action keyboard according to claim 1 wherein the arms , which all have similar arbitrarily designa ted forward and backward ends, are aligned substantially parallel to their respective keys, which all have similar arbitrarily designated forward and backward ends, and all said arms and keys pivotally mounted in respective arrays, with forward ends of the arms overlying back ends of the keys, the keys being pivotally mounted at intermediate positions thereof, the said electrical signal means comprising an array of switches lined up behind the said arms, each arm mounting on its back end, as said activating component of the signal means, a link which will act on one of said switches as the arm is removed in response to striking by the key, the range of motion of the said arm including a portion where the arm remains in contact with its activating key and a portion where the arm can be out of contact with its activating key, the electrical signal means having distinctly different responses to movement of the said arm in said different portions.

5. A piano-action keyboard for an electronic musical instrument comprising, a plurality of elongated keys, a supporting base, each of said keys being pivotally mounted on said supporting base,

OMP1 IPO 15

a plurality of arms pivotally mounted on said base, each arm being adjacent one end of a key and arranged so that when the key is pivoted, a driving force is imparted to the adjacent arm by direct striking of the arm by the key at a strike point, electrical signal means comprising a mechanical component mounted on each said pivoted arm and plural portions of said signal means each of which is responsive to movement of one said arm to generate an electrical signal as the associated arm moves including response to rate of movement of the arm, means defining an interface between each key and pivot-arm pair which varies the force.resolution components of the force transmitted to the arm by key pivoting so that an initial stage of key pivoting from an at rest position produces lower Fy and higher Fx components where y is the direction of movement of the arm portion at the strike point and y is the orthogonal to x compared to Fx and Fy at a later stage of key depression.

6. A piano-action keyboard according to claim 5 in which said interface is defined by a face on one of the said arm and key at the region of striking therebetween comprising a curved surface configured to present a varying curvature to said key as said key is pivoted.

7. A piano-action keyboard according to claim 5 in which said interface is defined by two intersecting planar surfaces.

8. A piano-action keyboard according to claim 5 and further comprising in connection with each arm a spring means mounted on said base and applying a force on its said arm in opposition to the force applied to the arm by depression of its key, and means pivotally mounting the said arm, the said strike region and distribution of weight of each arm being arranged so that the weight distribution applies an inertial force (as an unbalanced net weight) on said arm in oppo-^'

OMH .- IIPPOO sition to the force applied to the arm by the key.

9. A piano-action keyboard according to claim 8 which further comprises an upper frame extending over and above said pivoted arms, and arm stop means on said upper frame extending downward for contact by a heavily weighted portion of said arm at a limit of travel position thereof.

10. A piano-action keyboard according to claim 9 in which said spring is so selected as to apply to said arm a force less than the inertial force of said weight distribut o .

11. A piano-action keyboard according to claim 5 wherein the arms are aligned substantially parallel to their respective keys and all pivotally mounted in an array with forward ends of the arms overlying back ends of the key the keys being pivotally mounted at intermediate positions thereof, the said electrical signal means comprising an array of switches lined up behind the pivoted arms, each arm-mounting on its back end, as said mechanical component of the signal means, a link which will act on one of said switches as the arm is removed in response to striking by the key, the range of motion of the pivoted arm including a portion where the arm remains in contact with its activating key and a portion where the arm can be out of contact with its activating key, the electrical signal means having distinctly different responses to movement of the pivoted arm in said different portions.

12. A piano action keyboard according to either of claims 1 or 5 wherein the signal means are constructed and arranged so that initial arm movement is ineffective to generate a signal, and subsequent movement is so 17

effective, whereby the effect of initial accelerations of the key-arm mechanism output is attenuated.

13. Apparatus in accordance with claim 1, further comprising means defining said electrical switching element with an elongated compliant surface, deflection of which at one or more points produces one or more electrical _ switching changes and an actuating means selectively movable parallel to said compliant surface and, a coupling from the actuating means to the compliant surface to translate actuating means motions into compliant surface deflections with low dynamic friction and low effective-reaction force in- relation to the. actuating mechanism comprising a roller mounted from the actuating mechanism by a spring link to continuously contact said compliant surface.

14. Apparatus in accordance with claim 13 wherein the spring link is in a vee-bent sheet form with one end thereof secured to the actuating mechanism and the other free end thereof carrying the roller.

15. Apparatus in accordance with claim 14 wherein the carrying end of the spring is a deformed end of a spring thereof.

16. Apparatus in accordance with claim 13 wherein the link is in a sheet form with one end thereof secured to the actuating mechanism and the other free end thereof carrying the roller.

17. Apparatus in accordance with claim 16 wherein the carrying end of the spring is a deformed end of a spring thereof.

18. Apparatus In accordance with claim 13 wherein the compliant surface is ramped at an angle of 50-80° to horizontal.

19. Apparatus in accordance with claim 1 wherein said switching means comprise, electrical circuit portion means with at least a

-= REXCT-

O PI 18

triple layering of bottom, middle and top superimposed films of resilient plastic, the middle such film having multiple openings therein in a linear array, the films being tensioned and arranged so that portions of the bottom and top films have two relative positions, one of which is close proximity including ocntact or near contact of the two films and the other of which is lesser proximity, one of said positions being the at-rest position of the films portions in the region of each such opening and the other being the result of external actuation to at least one of the films (preferably the top film) , the positional changes of film portions in other openings of said aperture array, the film arrangement at each such opening in¬ cluding a capability of varying the form and/or time of assuming a form of the said position resulting from the application of external force depending on the exact point of application force and rate of application of the said external actuation, means defining electrical components selected from the class consisting of active devices, passive devices, switches, gates and interconnect wiring located in at said openings and each having multiple states in relation to an electrical circuit containing such components including at least a first state when the top and bottom films have said at rest positions and a second state In the other position and including in at least some of said open¬ ings, a third state resulting from variation of form of the said position due to variation of location, force and rate of said external actuation, and said switch means comprising a separate external force actuating linkage aligned with each opening of the linear array and arranged for independent actuation of the film portions at each such opening.

20. Apparatus in accordance with claim 19 and further comprising similar superimposed film arrangement 19

and collateral openings thereof with circuit elements therein located adjacent at least some of the openings of said linear array but out of the linear array, at least some of said actuating linkages being arranged.-to~.move between one of the openings of said linear array and at least one of said collateral aperature regions for selectively actua¬ ting the circuit components therein to change the state thereof.

21. Apparatus according to claim 20 wherein said electrical component is constructed and arranged so that initial arm movement is ineffective to generate a signal, and subsequent movement is so effective, whereby the effect of initial^" accelerations of the key-arm mechanism output is attenuated.