AT516096B1 - Keyboard for a musical instrument - Google Patents

Abstract

Keyboard (2) for a musical instrument (1), having a multiplicity of keys (3) which are pivotably mounted in a play tray (4) and counter to the force (F) of a spring element (6) supported in the play tray (4). depressible, wherein the spring element (6) comprises a spring (11) which is supported by a shape memory alloy containing member (12) in the play tray (4), wherein the shape memory alloy with the aid of a controllable power source (9) is activated, and the member (12) comprises a slide (13) slidingly mounted in the play tray (4) on which the spring (11) is supported, and an actuator (14) made at least partially of the shape memory alloy, by means of which the slide (13) along the inner bottom (4 ') of the play tray (4) is displaceable.

Description

The present invention relates to a keyboard for a musical instrument, comprising a plurality of keys, which are pivotally mounted in a play drawer and each depressible from a rest position against the force of a spring loaded in the play drawer in a lowered position, wherein the Spring element comprises a spring which is supported via a shape memory alloy containing member in the play tray, wherein the shape memory alloy is activated by means of a controllable energy source, so that the force of the spring element is dependent on the degree of activation of the shape memory alloy.

Claviatures of this kind are used in - usually electronic - musical instruments that mimic pianos, but also completely different, even keyless instruments sound. As far as possible, not only by means of suitable impact sensors but also the impact dynamics, i. the volume and tone color of the key associated with the key being played, depending on the severity of a key attack, but also the weight of the keys, i. the actually required for the attack of the keys force and its course depending on the key position, a classic piano modeled.

From EP 1 356 449 B1 and the references cited therein, musical instruments in the form of electronic pianos are known, in which an electromechanical actuator for exerting a force acting on the key in its rest position is provided for each key, the force being removed. and is speed-dependent controlled in order to provide the musician as natural as possible key weighting and thus a feel like a real piano. The use of such actuators allows the generation and control of any, even variable characteristics of the force. However, the demands on the actuators and in particular on the control are very high, since they have to generate and control the force required to achieve a lifelike feel sufficiently quickly and accurately.

From JP 2008 157 999 A a keyboard of the aforementioned type is known in which the shape memory alloy member is below a coil spring and the same acts in the axial direction, which allows only limited adjustments of the spring force.

The invention has for its object to provide a keyboard for a musical instrument, which is able to produce in an improved manner a variable key weighting.

This object is achieved with a keyboard of the aforementioned type, which according to the invention is characterized in that said member comprises a slidably mounted in the play tray slide on which the spring is supported, and at least partially made of the shape memory alloy actuator , by means of which the carriage is displaceable along the inner bottom of the play tray.

As shape memory alloys (or "memory metals") metal alloys are referred to, which may be present in two different crystal structures (also called "phases"). A shape memory alloy deformed in its non-activated phase decreases upon activation, e.g. by applying a magnetic field or by increasing the temperature, as a result of a transformation of its crystal structure, it reverts to the original shape, with a very high specific working capacity, i. Ratio of work done to volume of material.

A typical example of thermally activatable shape memory alloys are nickel-titanium alloy whose alloy ratio makes the activation temperature adjustable within a wide range.

By means of such a spring element with a shaped alloy, a keyboard for a musical instrument is provided in which the key weighting is variable as needed. By a corresponding geometric design of the spring element even a complex, Tastenweg- and speed-dependent key weighting is replicated. In this case, by activating the shape memory alloy between two or more states or

Switched forces of the spring element or the power can be changed even stepless by appropriate control of the power source. Depending on the design of the spring element, a shape memory alloy with a two-way effect can be used, which has a preferred shape both in the activated and in the non-activated state, or a shape memory alloy with a one-way effect, which assumes a certain shape upon activation and without activation of an antagonist , eg a spring, a counterweight or another component of shape memory alloy, is reset.

According to the invention, the spring element on a spring which is supported via a shape memory alloy containing member in the play drawer. This allows a modular design of the spring element, so that different springs and members in different keyboards or in different keys of a keyboard combined can be used. Moreover, points of contact between member and spring as well as their relative arrangement with each other, e.g. the angle between travel and movement of the shape memory alloy-containing member is readily adaptable to the requirements, thereby optionally providing highly nonlinear relationships between activation of the shape memory alloy and force of the spring member on the key.

According to the invention, said member comprises, as discussed, a slide slidably mounted in the play drawer, on which the spring is supported, and an actuator made at least partially of the shape memory alloy, by means of which the slide is slidable along the inner bottom of the play drawer. In this case, the spring may be mounted on the carriage, or the carriage is wedge-shaped and the spring rides on it by means of a sliding block, or else the spring is a leaf spring and is supported on the carriage, whereby the effective length of the leaf spring by the movement of the Sled is changeable. The leaf spring may preferably be approximately double S-shaped in side view. All these variants allow a particularly sensitive adjustment of the spring force and thus adjustment of the key weighting.

, When the spring element is made in different areas of different shape memory alloys is particularly favorable. As a result, a different degree of activation of the shape memory alloys can be achieved with the same amount of energy applied, whereby the degree of activation, which is approximately linear over a certain activation range, of one shape memory alloy is widened by that of another shape memory alloy or, on the other hand, the effect of the shape memory alloy in one area of the spring element by that of the shape memory alloy in another Reinforced area or, depending on the geometry of the spring element, if desired, also weakened and / or its effective direction is deflected.

Alternatively or additionally, it is also advantageous if the energy source is adapted to apply different amounts of energy to the shape memory alloy in different areas of the spring element. In this way, the effect of the shape memory alloy is more precisely controllable and the approximate linearity of the degree of activation can be extended to a wider range. In this way, the effect of the shape memory alloy in one area of the spring element can also be controlled in a particularly simple manner to reinforce the effect of the shape memory alloy in another area or against it, and thus, for example. a return to a starting position of the spring element and / or a completely non-linear change of the key weight can be achieved.

It is particularly advantageous if the energy source is an electrical resistance heater, by means of which the shape memory alloy is thermally activated. Such a thermal activation is - compared to a required for certain shape memory alloys magnetic activation - particularly easy to do and very precisely controlled. In the simplest case, the resistance heater comprises a current source and a resistance wire wound around the spring element or the shape memory alloy contained therein. Such resistance heating is flexible, inexpensive and durable. Also, by suitable winding arrangement on the spring element, e.g. only in the area of the shape memory alloy can the exact location of the heating be determined in a simpler way.

In an alternative embodiment, the power source is an electric current source and the shape memory alloy formed as an electrical resistance, in turn, it is thermally activated. This leads to a particularly simple construction of the spring element and the energy source with a particularly small number of parts and also to a simple controllability by means of current regulator.

In a further, alternative embodiment, the energy source is a Peltier element with electrical feed, by means of which the shape memory alloy is thermally activated. In this way, the degree of activation of the shape memory alloy is directly adjustable, or regulated, since the Peltier element not only allows a very simple and precise controllable heating of the shape memory alloy, but - if desired or necessary - the same Peltier element by simply reversing the electric current flow can also be used for cooling.

It is particularly advantageous if the spring element is associated with a temperature sensor which controls the energy source is particularly advantageous. As a result, the degree of activation of the shape memory alloy depending on the actual temperature of the spring element and thus at any ambient temperature is controlled with high accuracy. In particular, in the embodiment of the energy source as a Peltier element with electrical supply for the thermal activation of the shape memory alloy thereby a particularly precise temperature control by demand-dependent heating or cooling is possible.

In a particularly advantageous embodiment of the invention, a controller is provided for a plurality of keys, which controls a common source of energy sources or separate energy sources. This reduces the control effort while fully maintaining the adjustability of the force required to depress each key. In this case, the forces of the spring elements of all the keys can be controlled together or several keys are grouped together and the forces of all the keys of each group are controlled independently of those of other groups and thereby, for example, the forces of the black irrespective of those of the white keys or forces the keys of lower octaves of the keyboard independently of those of higher octaves.

The invention will be explained in more detail with reference to embodiments shown in the accompanying drawings. In the drawings: Fig. 1 shows a musical instrument with a device according to the invention

Keyboard in schematic plan view; Fig. 2 shows the musical instrument of Fig. 1 in a schematic cross section; FIG. 3 shows an example of the degree of activation of a thermally activatable shape memory alloy as a characteristic over temperature; FIG. Figures 4 to 8, 9a and 10a show various embodiments of the keyboard

Fig. 1 and its spring element in each case in cross section; and FIGS. 9b to 9e and 10b and 10c respectively show variants of the spring elements of FIGS. 9a and 10a, partially with resistance wires for thermal activation (FIGS. 9d and 9e), in a perspective view obliquely from above.

Figs. 1 and 2 show a musical instrument 1 with a keyboard 2, which has a plurality of keys 3. The keys 3 are pivotally mounted in a play tray 4 on an axis 5 and in each case by a rest position S-ι (Fig. 2, 4a, 4c) against the force F of a supported in the play tray 4 spring element 6 in a lowered position S2 (Fig 4b, 4d) depressible.

Upon depression of a key 3, in a manner known to those skilled in the art, by means of a sensor element 7, e.g. a motion or touch sensor, and an electric or electronic audio frequency generator 8 (sound generator, SG) controlled therefrom generates a sound associated with the depressed key 3. Alternatively, the clay could also be made in a purely mechanical way, e.g. be excited by attacks of a tensioned string.

The spring element 6, whose structure will be explained in detail below with reference to various embodiments according to FIGS. 4 to 10, is at least partially made of a shape memory alloy, which by means of a controllable power source 9, e.g. an electric power source 9 ', can be activated. The force F of the spring element 6 is dependent on the degree of activation of the shape memory alloy. Using the shape memory alloy, e.g. either a spring stiffness or a spring travel of the spring element 6 are reversibly influenced.

Shape memory alloys have two distinct crystal structures ("phases"), wherein a shape memory alloy deformed in its non-activated phase, upon activation, i.e. upon conversion to the activated phase, reverts to its original shape by application of a magnetic field or by temperature elevation.

Fig. 3 shows an exemplary characteristic curve 10 for a thermally activated shape memory alloy, wherein the degree of activation a, i. the proportion of the shape memory alloy in its activated (high temperature) phase, above the temperature T, is shown. A magnetically activatable shape memory alloy would have a comparable characteristic 10 over the magnetic field strength.

The degree of activation α is typically approximately linear in a certain temperature range B, so that the shape memory alloy can be targeted only partially activated, and it also performs only a part of that work, which is able to perform at full activation.

For activation, a common controlled energy source 9 may be provided for several or even all of the keys 3 of the keyboard 2; In the example of FIG. 1, the keyboard 2 each has a controlled current source 9 'for the uppermost octave and for the remaining (lower) octaves. It is understood that, alternatively, each key 3 could have its own energy source 9, 9 ', which is controllable separately (see FIG. 2) or together with other keys (not shown), and that the musical instrument 1 furthermore has an arbitrary number may have on keys 3.

4 to 10 illustrate the operation of the variable application of force of the key 3 using exemplary, not to be considered as limiting variants of the spring element 6. In this case, FIGS. 4 to 7 different spring elements 6, each with a spring 11, the is supported by a shape memory alloy containing member 12 in the play tray 4.

The said member 12 according to the example of Fig. 4a to 4d comprises a slidably mounted in the play tray 4 carriages 13, on which the spring 11 - here: a coil spring - sits and the force F exerts on the key 3, and The carriage 13 is displaceable by the helical actuator 14 in this example along the inner bottom 4 'of the play tray 4 up to a position Pi on a stop lug 15. In the rest position S-1 of the key 3 according to FIG. 4 a, the spring 11 is already preloaded in the play tray 4, so that it exerts the force F on the key 3. If the key 3 is pressed down in a lowered position S2 according to FIG. 4b, the spring 11 is further tensioned; the force F acting on the key 3 changes as a function of the characteristic curve of the spring 11.

If the shape memory alloy of the actuator 14 is activated (Fig. 4c), it pulls the carriage 13 from the position Pi in one of them depending on the degree of activation α more or less spaced position P2 and tilts the spring 11, thereby increasing their bias already reduced in the rest position Si against the key 3. Consequently, the spring 11 is also in the lowered position S2 of the key 3 of FIG. 4d at a lower voltage and the force F, which must apply a musician when depressing the key 3, as low as in non-activated shape memory alloy according to Fig. 4a and 4b. Thus, the degree α of the activation of the shape memory alloy determines the magnitude of the force F of the spring element 6.

In order to guide the carriage 13 back to the position P-1 on the stop lug 15, it is sufficient if the actuator 14 is made of a shape memory alloy with a two-way effect, in which case it is active both in the activated and in the non-activated state. activated state has a preferred form (which leads to the positions Pi or P2 of the carriage 13 according to FIGS. 4a and 4c), or if the member 12 comprises a return element (not shown), for example another spring or on the other hand, a further actuator, by which the carriage 13 is acted upon or acted upon against the stop lug 15.

5a to 5d show - analogous to FIGS. 4a to 4d - an alternative embodiment of the member 12 with a wedge-shaped carriage 13 ', which moves from the actuator 14 between the two positions P-ι and P2 in the manner mentioned becomes. On the sloping top of the wedge 13 'rides the lower end of the spring 11 with a sliding block 11', which is guided vertically (in a manner not shown) in the play tray 4 and / or on the key 3 to the bias of the spring 11th depending on position P1; P2 of the wedge 13 'to change.

E in a further alternative embodiment, Figs. 6a and 6b, wherein the spring 11 rests on the member 12 of the actuator 14 and a carrier 16 which, in contrast to the carriage 13 according to the example of Fig. 4a to 4d not displaced approximately transversely to the force F but about parallel to it is raised or lowered by the actuator 14 with the shape memory alloy during their activation, which in turn changes the bias of the spring 11. In this arrangement of spring 11 and actuator 14, a separate return element for the actuator 14 can be omitted. Further, optionally, the actuator 14 could be directly, i. elimination of the carrier 16, attack the spring 11.

Actuator 14 with the shape memory alloy according to the example of FIGS. 7a and 7b displaces upon activation a support block 17 designed as a slide with which it forms the member 12 on the inner bottom 4 'of the play tray 4. On the support block 17 is a side view approximately double S-shaped leaf spring 18 of the spring element 6 against the play tray 4 is supported. As a result, the effective length L of the leaf spring 18 and thus the force F depending on the degree of activation α of the shape memory alloy of the actuator 14 is changed.

Fig. 8 shows a variant of the spring element 6, in which this consists of tensioned between game load 4 and button 3 spring 11 and arranged parallel thereto, the spring 11 optionally but not necessarily touching actuator 14 with the shape memory alloy, so that upon activation of the shape memory alloy add the forces of the spring 11 and the actuator 14. For this purpose, the actuator 14 could alternatively also in the interior of the spring 11 -or vice versa - be arranged.

It will be understood that the spring element 6 is shown in a different geometry than shown in Figs. 4 to 8, e.g. by scissor-shaped arrangement of a plurality of springs 11 and / or members 12, or with other types of springs, e.g. Cone, wave, thigh or coil springs, torsion, Evolut-, leaf or disc springs or rubber or gas springs, may be constructed.

In the variants of Figs. 9a to 9e, the spring element 6 is a side-view approximately S-shaped leaf spring 18 which is supported on a leg 18 'of the "S" in the play tray 4 and e.g. 9b is urged by a screw 20 therein and its other leg 18 "urges the key 3. Such a leaf spring 18 may be U-shaped in plan view as shown in Fig. 9b and may have portions 19a to 19g of at least partially mutually different materials For example, the entire leaf spring 18 and thus the entire spring element 6 may be completely made of a shape memory alloy or, for example, the regions 19a, 19d, 19g of spring steel and the regions 19b, 19c, 19e and 19f of (optionally different) shape memory alloy (s) be made with spring steel.

In another embodiment according to Fig. 9c, the spring element 6 and the leaf spring 18 is partially reinforced with rods 21 of shape memory alloy. This reinforcement could alternatively extend over the entire leaf spring 18 and / or the rods 21 consist of different shape memory alloys.

In the following, various possibilities for activating the shape memory alloy will be explained with reference to the examples shown in FIGS. 9b to 9e, which are to be applied mutatis mutandis in another embodiment of the spring element 6.

The shape memory alloy of the spring elements 9 according to FIGS. 9b and 9c is thermally activated by connecting a controlled current source 9 '(not shown) to contacts 22 at the two ends of the leaf spring 18 which is approximately U-shaped in plan view. wherein the spring element 6 and the leaf spring 18 is designed for thermal activation of the shape memory alloy as an electrical resistance.

Alternatively (or additionally), according to FIGS. 9d and 9e, an electrical resistance heater as the energy source 9 can thermally activate the shape memory alloy. In this case, by a controllable electrical power source 9 '(not shown), e.g. an electrical resistance wire 23 is fed, which is at least partially wound around the spring element 6.

Alternatively, the power source 9, e.g. with two separately controllable electrical current sources 9 '(not shown) for two separate resistance wires 23 according to Fig. 9e, the shape memory alloy in different areas of the spring element 6 different degrees of energy.

It is understood that the resistance wire 23 with the shape memory alloy may be in direct thermal conductive connection but need not and the leaf spring 18 does not have to embrace, but for example, could also be located only in the vicinity of the shape memory alloy.

Alternatively, the energy source 9 could be a Peltier element with electrical feed, with which the shape memory alloy is thermally activated. Further, the power source 9 may be a heat radiation source, e.g. an infrared radiation source, or - in magnetically activated shape memory alloy - an electromagnet with electrical feed (not shown).

Optionally, the spring element 6 is associated with a temperature sensor (not shown), which regulates the power source 9 and thus the temperature of the spring element 6.

In the example of FIGS. 10a to 10c, the spring element is a U-shaped wire bracket 24 whose one leg 24 'is supported in the play tray 4 and optionally, e.g. By means of the screw 20, it is anchored therein and its other leg 24 "bears the force of the key 3. According to the examples shown in FIGS. 10a and 10c, such a spring element 6 could for example be in the region of the bend of the" U "and thus at least partially with a support 25 be reinforced from shape memory alloy, alternatively, the entire such designed spring element 6 could be made of shape memory alloy (not shown).

According to Fig. 10b, the U-shaped wire bracket 24 on the one hand be double-U-shaped and in plan view U-shape or consist of one or two approximately parallel U-shaped wire brackets 24 as shown in FIG. 10c, the two Supports 25 can optionally be made of different shape memory alloys and / or can be subjected to different amounts of energy.

The invention is not limited to the illustrated embodiments, but includes all variants and modifications that fall within the scope of the appended claims.

Claims (12)

claims 1. Keyboard for a musical instrument, with a plurality of keys which are pivotally mounted in a play tray and each depressible from a rest position against the force of a supported in the play load spring element in a lowered position, wherein the spring element comprises a spring over a shape memory alloy containing member is supported in the play drawer, the shape memory alloy being activatable by a controllable energy source, such that the force of the spring member is dependent on the degree of activation of the shape memory alloy, characterized in that said member (12) is one in the play drawer (4) slidably mounted carriage (13) on which the spring (11) is supported, and an actuator (14) made at least partially of the shape memory alloy, by means of which the carriage (13) along the inner bottom (4 ') of the play drawer (4) is displaceable. 2. Keyboard according to claim 1, characterized in that the spring (11) on the carriage (13) is fixed. 3. keyboard according to claim 1, characterized in that the carriage (13) is wedge-shaped and thereupon the spring (11) by means of a sliding block (1T) rides. 4. Keyboard according to claim 1, characterized in that the spring (11) is a leaf spring (18) and on the carriage (13) is supported, whereby the effective length (L) of the leaf spring (18) by the movement of the carriage ( 13) is changeable. 5. keyboard according to claim 4, characterized in that the leaf spring (18) is approximately double S-shaped in side view. 6. Keyboard according to one of claims 1 to 5, characterized in that the spring element (6) in different areas (19a - 19e) is made of different shape memory alloys. 7. Keyboard according to one of claims 1 to 6, characterized in that the energy source (9) is adapted to apply the shape memory alloy in different areas of the spring element (6) with different levels of energy. 8. Keyboard according to one of claims 1 to 7, characterized in that the energy source (9) is an electrical resistance heater (9 ', 23), by means of which the shape memory alloy is thermally activated. 9. keyboard according to one of claims 1 to 7, characterized in that the energy source (9) is an electric current source (9 ') and the shape memory alloy is formed as an electrical resistance, so that it is thermally activated. 10. Keyboard according to one of claims 1 to 7, characterized in that the energy source (9) is a Peltier element with electrical supply, by means of which the shape memory alloy is thermally activated. 11. Keyboard according to one of claims 1 to 10, characterized in that the spring element (6) is associated with a temperature sensor which controls the energy source (9). 12. Keyboard according to one of claims 1 to 11, characterized in that for several keys (3), a control is provided which one of the keys (3) common energy source (9, 9 ') or separate energy sources (9, 9' ) controls. For this 6 sheets of drawings