EP0698267B1 - Electromechanical piano - Google Patents

Abstract

The present invention concerns a piano comprising a computer-controlled electric motor/sensor (31) as actuating means for each of its hammers (2). Each key of the keyboard is composed of a flat, modular motor/sensor (40) coupled to a processing system (34), the output of the motor/sensor (40) determining, by means of the processing system, the displacement of at least one of the hammer motors (31).

Description

The present invention relates to a piano.

A classical piano is a musical instrument which includes strings capable of being struck by hammers, a keyboard and a mechanical connection system between each key of the keyboard and a hammer. This mechanical connection system is one of the key elements of a piano and has been the subject of numerous studies and numerous improvements, in particular with regard to the so-called single-exhaust and double-exhaust systems.

Figure 1 very schematically illustrates such a connection system between a key and a hammer. A string 1 fixed to the piano frame, symbolized by hatching, is likely to be struck by a hammer 2 and, in the absence of actuation, to be damped by a damper 3. The head of the hammer, generally provided of a felt, is connected by a handle 4 to an axis 6. A key 10 is articulated around an axis 11 and is capable of throwing the hammer towards the rope by means of a launching lever 13 recalled by a spring R. A cam system 14, 15 means that, after an initial propulsive stroke, the launch lever 13 "escapes" relative to the zone 15 at which the end of this lever presses on the hammer handle. Thus, an initial impulse on the key launches the hammer and causes it to strike the string while a slow movement of the key has no action. To avoid rebounds of the hammer, there is provided a part 17, called catch, which dampens the return of this hammer. A handle 19 of the damper 3 is also pressed by the button when the latter is pressed and the damper 3 is then moved away from the rope and then comes back into place under the effect of its own inertia when the button is released.

The representation of Figure 1 and the description above are extremely succinct and are only intended to remind that a key / hammer link mechanism is a complex mechanism in a piano. This mechanism is delicate to manufacture and susceptible to wear or adjustment. Its adjustment, replacement and repair are difficult and require the use of highly qualified specialists who are fewer and fewer in our time.

In addition, electronic pianos are known in which there are no longer strings but electronic oscillator and speaker systems which aim to reproduce the sound of strings struck or plucked. In fact, these electronic instruments, including digital pianos, synthesizers and electronic organs, are instruments different from traditional pianos because they never manage to reproduce exactly the sounds of strings struck but on the other hand allow new musical possibilities.

Pneumatic or mechanical pneumatic systems are also known in which the hammers of a piano without keyboard are propelled by a jet of air penetrating into the instrument thanks to the perforations of a paper roll in correspondence with the holes of a rule. These systems are generally relatively primitive and the recording mode does not provide music of the same quality as that played on a classical piano.

In order to make the keyboard of an electronic piano similar in its touch to the keyboard of a classical piano with mechanical connection between key and hammer, American patent 5 107 262, Claude Cadoz et al., "Modular Retroactive Keyboard and a Flat Moduler Actuator "describes a keyboard made up of modular elements with motors / sensors coupled to a computer, each of which can simulate exactly the behavior of a classical piano key or another keyboard instrument. The signals emitted by these modules are coded in various ways and sent to a computer which manages them to memorize them or operate conventionally an electronic piano or other synthesizer.

An approach to the retroactive simulation and coding mode suitable for musical systems is for example described in Computer Music Journal, Volume 8, N ° 3, 1984, pp 60-73, C. Cadoz et al., "Responsive Input Devices and Sound Synthesis Simulation of Instrumental Mechanism: The CORDIS System "; in International Computer Music Conference Proceedings 1986, J.L. Florens et al., "Optimized Real Time Simulation of Objects for Musical Synthesis and Animated Images Synthesis"; and in Computer Music Journal, Volume 17, N ° 1, 1993, pp 19-29, C. Cadoz et al., "CORDIS-ANIMA: A Modeling and Simulation System for Sound and Image Synthesis- the General Formation".

In addition, it is stated in the aforementioned US patent that motors / sensors having a keyboard function can also constitute actuators. In this case, the processor providing a feedback control signal in response to the key signal is controlled by an image signal from that normally provided by the key. It is also known from document US-A-4,970,928 an electro-mechanical piano comprising as actuating means of each of its keys a system both sensor and motor controlled by computer.

An object of the present invention is to provide a piano structurally identical in its generating part of sound (strings struck) to a conventional piano, and whose string striking system is simplified.

Another object of the present invention is to provide such a piano having a keyboard functionally identical for the user to the keyboard of a conventional piano but in which the key / hammer link mechanism is simplified.

Another object of the present invention is to provide a piano which can behave in a strictly identical manner to a conventional piano but provided with additional possibilities of recording and modification of the pianist's playing or modification of the sounds provided.

To achieve these objects, the present invention provides a piano comprising as a means of actuating each of its hammers an electric motor / sensor controlled by computer.

According to an embodiment of the present invention, each key on the keyboard of this piano consists of a flat modular motor / sensor coupled to a processing system and the output signals of which determine, via this processing system , the displacement of at least one of said motors / sensors.

According to an embodiment of the present invention, this piano comprises means for memorizing the sequence of the signals produced by each key actuation.

According to an embodiment of the present invention, each actuation / key motor / sensor is connected to a signal bus of a processing processor by a forward link comprising a position sensor and an analog / digital converter and a return link comprising a digital / analog converter and an amplifier.

According to an embodiment of the present invention, the processing processor is associated with a sampling clock and takes into account the position information of each analog / digital converter at each clock time and provides reaction information at each digital / analog converter at each following clock time.

• la figure 1 représente très schématiquement un mécanisme de liaison touche/marteau d'un piano classique ;
• la figure 2 représente un système de liaison touche/ marteau selon la présente invention ; et
• la figure 3 est un schéma plus détaillé d'un mode de réalisation d'un système de liaison touche/marteau selon la présente invention.

These objects, characteristics and advantages as well as others of the present invention will be explained in detail in the following description of a particular embodiment made in relation to the attached figures, among which:

• Figure 1 very schematically shows a key / hammer link mechanism of a conventional piano;
• FIG. 2 represents a hammer / hammer connection system according to the present invention; and
• Figure 3 is a more detailed diagram of an embodiment of a key / hammer connection system according to the present invention.

In the following description, it will be assumed that the European patent application 365 441 is known as well as the American patent 5 107 262 which both claim priority from the French patent application 88/14064 of the applicant.

In the system according to the present invention illustrated in FIG. 2, there is a string 1 fixed to a piano frame, these two elements being in no way modified compared to a conventional piano. As before, the rope is capable of being struck by a hammer head 2 and damped by a damper 3. But, according to the present invention, the hammer and the damper are mounted on the head 30 of the axis of a motor / sensor 31 controlled by a microcontroller or computer 34. A first link 35 supplies the motor 31 with the control signals coming from the computer 34 and a second link 36 returns information received by the computer to the computer 34 motor sensor / sensor on the positions and movements of the hammer at all times when it moves then strikes the rope 1.

An embodiment of a flat modular actuator which can serve as a motor / sensor 31 is described in the patents cited above. It will be noted that the conventional difference between strings is of the same order of magnitude as the difference between keys of a keyboard and therefore that the production of flat modular actuators making it possible to satisfy the dimensional constraints of a keyboard suitable for producing a motor / sensor 31 according to the present invention.

The computer 34 can control the various meters 31 arbitrarily under the effect of a pre-stored program and possibly designed in a computerized manner. Those skilled in the art will find the information useful for programming the computer to fulfill a desired function in the various articles mentioned above.

It can also be provided that the piano according to the present invention has exactly the same function as a conventional piano. For this, the conventional keyboard of a piano is replaced by a keyboard made up of motors / sensors 40 each of which is coupled to the computer 34 by a forward link 41 and a return link 42.

FIG. 3 shows in a little more detail and in the form of blocks the electronic arrangement of the connection system between the motors / sensors of the hit 40 and the motors / sensors of the hammer 31. Each circuit / sensor 40 is associated with a circuit sensor electronics 50 which supplies an analog / digital converter 51 with a quantity indicative of the movement of a key. The key sensor 40 receives, via a digital / analog converter 53 and an amplifier 54, signals from a signal bus 56 coupled to a processing processor 58. A digital converter / analog 60 receives information from the signal bus 56 and supplies it via an amplifier 61 to the motor / sensor 31. Any movement of this motor / sensor 31 is processed by an electronic circuit 63 which supplies the information of position corresponding to signal bus 56 via an analog / digital converter 64.

The processing system may include the aforementioned processing processor 58 associated with a management processor 66 coupled to a communication network by an input access / output 68, and associated with a mass memory 69 and with a control panel 70. It is possible to use a set of processing processors each of which is associated with one or more sets of motors / sensors 40, 31, all of these processing processors being associated with a single management processor managing all the keyboard and all the motors / hammer sensors. In the context of the following description, to simplify the case where there is provided a single processing processor 58 and a single signal bus 56. The management processor 66 is preferably a local management microprocessor which allows management of the operating modes of the processing processor 58, that is to say for example the choice of processing models, the adjustment of the parameters, the configuration of the key / hammer links. Preferably, the mass memory 69 associated with the management processor 66 contains all the programs capable of being used by the processing processor 58. The processing processor 58 also includes an input / output access 71 making it possible to supply signals Midi type standard (Musical Instrument Digital Interface) intended to control a synthesizer, or on the contrary to receive Midi codes to directly actuate hammer motors / sensors.

In a rough preferred operation, the positions of the keys and hammers, provided by the analog / digital converters 51 and 64 are sampled at a fixed rate, typically of 1 kHz and the processing processor calculates from these samples, at the rate where they are supplied, the reaction forces to be supplied to the motors / sensors 40 and 31, these reaction values being sent to the digital / analog converters 53 and 60 at each following sampling period.

• le levier de lancement 13 qui intervient dans la phase d'accélération du marteau à partir de la position de repos de la touche ; au-delà du seuil d'échappement, l'effet de ce marteau de lancement disparaît grâce à la pièce 14 et n'est retabli que par le retour de la touche à sa position de repos sous l'effet du ressort de rappel R ;
• l'attrape-marteau 17 qui constitue un lien rigide entre la touche et le marteau, avec un fort effet de viscosité : tout se passe comme si, en plus du lien rigide, un frottement visqueux avec le bâti intervenait. Ce lien permet l'amortissement du mouvement du marteau après impact et retour à la position de repos. Le rapport cinématique par cette deuxième liaison de la touche au marteau est différent de celui établi par le levier de lancement.

To calculate the reaction forces to be applied to each motor / sensor in response to position detections, we use a model based on the simplified representation of a piano appearing in figure 1. This model includes two kinematic chains linking the movement of the key to that of the hammer. These chains include:

• the launch lever 13 which intervenes in the hammer acceleration phase from the rest position of the key; beyond the exhaust threshold, the effect of this launch hammer disappears thanks to the part 14 and is only restored by the return of the key to its rest position under the effect of the return spring R;
• the hammer catcher 17 which constitutes a rigid link between the fingerboard and the hammer, with a strong viscosity effect: everything happens as if, in addition to the rigid link, a viscous friction with the frame intervened. This link allows the damping of the hammer movement after impact and return to the rest position. The kinematic ratio by this second connection of the key to the hammer is different from that established by the launch lever.

These are the forces of gravity that bring the fingerboard and the hammer back to their meal position.

• Les éléments matériels correspondent à des pièces fixes ou mobiles possédant une inertie. Ces éléments sont simulés par un processus recevant des forces et produisant des positions.
• les éléments de liaison déterminent les forces de liaison entre les éléments matériels. Ils sont simulés par des processus recevant des positions et produisant des forces.

The analysis of a mechanism described by this model shows that it comprises two types of elements: material elements and connecting elements.

• The material elements correspond to fixed or mobile parts having inertia. These elements are simulated by a process receiving forces and producing positions.
• the connecting elements determine the connecting forces between the material elements. They are simulated by processes receiving positions and producing forces.

In the context of the model considered, the material elements are the fingerboard, the hammer, the fixed frame. The connecting elements are the two kinematic chains of the hammer key, namely that of the launch lever 13 and that of the catch 17; the linkage of the hammer rest stop this one to the frame; the links of the restoring force type connecting the key and the frame on the one hand, the hammer and the frame on the other hand which are, as indicated above, links which correspond to the forces of gravity.

STIMULATION ALGORITHM OF THE VARIOUS CONSTITUENTS 1. Connection by launch lever 13

• a) la partie visco-élastique dont le calcul de force est défini par les équations suivantes :
  • force appliquée au marteau $$\begin{gathered} \text{Fm(n+1) = K(n)*[Xm(n)-R*Xt(n)-L] +} \\ \text{Z(n)*[Xm(n)-Xm(n-1)-R*Xt(n)+R*Xt(n-1)]} \end{gathered}$$
    
    où
    • n-1, n et n+1 désignent trois périodes d'échantillonnage successives
    • Fm(n) indique la force appliquée au marteau pendant la période d'échantillonnage n,
    • Xm(n) désigne la position du marteau à l'instant n, et R et L sont des constantes.
  • force appliquée à la touche (Ft) : $$\text{Ft(n+1) = -R*Fm(n+1)}$$
    
• b) Le coetrôle des paramètres K(n) et Z(n)

This bond is represented by a viscoelastic bond whose stiffness K and viscosity Z parameters are variable at each sampling step. The processing therefore consists of two parts:

• a) the visco-elastic part whose force calculation is defined by the following equations:
  • force applied to the hammer $$\begin{gathered} \text{Fm (n + 1) = K (n) * [Xm (n) -R * Xt (n) -L] +} \\ \text{Z (n) * [Xm (n) -Xm (n-1) -R * Xt (n) + R * Xt (n-1)]} \end{gathered}$$
    
    or
    • n-1, n and n + 1 denote three successive sampling periods
    • Fm (n) indicates the force applied to the hammer during the sampling period n,
    • Xm (n) denotes the position of the hammer at time n, and R and L are constants.
  • force applied to the key (Ft) : $$\text{Ft (n + 1) = -R * Fm (n + 1)}$$
    
• b) The co-control of the parameters K (n) and Z (n)

It is a two-state automaton whose inputs are the positions of the hammer Xm and the key Xt. The two states of this automaton represent the two states of the launch lever 13 of FIG. 1. These are the "free" state and the "linked" state.

The transition table with the corresponding produced values for K and Z is as follows, Ste being a fixed parameter adjusted once and for all which determines the escape threshold. Xt key position (n) Pos. relative Hammer / Key Xm (n) -R * Xt (n) State (n) State (n + 1) K (n + 1) Z (n + 1) <Ste > 0 Free Related 0 0 > Ste > 0 Free Free 0 0 <Ste <0 Free Free 0 0 > Ste <0 Free Free 0 0 <Ste > 0 Related Related 0 0 > Ste > 0 Related Free 0 0 <Ste <0 Related Related Knockout ZO > Ste <0 Related Free 0 0

The parameters L and B can vary under the control of the management processor, for example to correspond to the action of a mute pedal which modifies in a real device the rest position of the hammer and therefore makes it possible to modify its striking speed for a given keyboard touch.

2. Connection by trap 17

• a) Partie visco-élastique
  • Force appliquée au marteau: $$\begin{gathered} \text{Fm(n+1) = K(n)*[Xm(n)=R*Xt(n)-L] +} \\ \text{Z(n)*[Xm(n)-Xm(n-1)-R*Xt(n)+R*Xt(n-1)] +} \\ \text{Zs(n)*[Xm(n)-Xm(n-1)]} \end{gathered}$$
    
  • Force appliquée à la touche: $$\text{Ft(n+1) = -R*Fm(n+1).}$$
    
• b) Partie contrôle des paramètres:

This bond appears as a viscoelastic bond between the fingerboard and the hammer (stiffness K, viscosity Z) and a viscous bond (viscosity Zs) between the hammer and the frame. The corresponding parameters are as in the previous case variable at each step and controlled from the positions of the key and the hammer.

• a) Visco-elastic part
  • Force applied to the hammer: $$\begin{gathered} \text{Fm (n + 1) = K (n) * [Xm (n) = R * Xt (n) -L] +} \\ \text{Z (n) * [Xm (n) -Xm (n-1) -R * Xt (n) + R * Xt (n-1)] +} \\ \text{Zs (n) * [Xm (n) -Xm (n-1)]} \end{gathered}$$
    
  • Force applied to the key: $$\text{Ft (n + 1) = -R * Fm (n + 1).}$$
    
• b) Parameter control part:

The link has two states, the free state and the linked state, but unlike the link by the launch lever, the state is not memorized and is determined at each sampling step as a function of the relative positions of the key. and hammer. The following table characterizes this parameter control module Pos. relative Hammer / Key Xm (n) -R * Xt (n) K (n + 1) Z (n + 1) Zs (n + 1) > 0 0 0 0 <0 K1 Z1 Zs1

3. Link stimulating the hammer rest stop

b) contrôle des paramètres Pos Marteau (Xm) K(n+1) Z(n+1) >0 0 0 <0 K2 Z2 This connection is of the visco-elastic type between the hammer and the frame with parameter control by an automaton without memory as before.
a) Visco-elastic part:
Force applied to the hammer: $$\begin{gathered} \text{Fm (n + 1) = [K (n) * [Xm (n) -L] +} \\ \text{Z (n) * [Xm (n) -Xm (n-1)]} \end{gathered}$$

b) control of parameters Hammer Pos (Xm) K (n + 1) Z (n + 1) > 0 0 0 <0 K2 Z2

4. Links simulating gravity

These are additional constant forces applied to the hammer and fingerboard.

Then, the summation of the various elements of the force is carried out. A calculation corresponding to the model designated above is easily implemented by programming to be carried out by the processing microprocessor 58.

An advantage of the piano according to the present invention is that it will have for the user exactly the same characteristics as a conventional piano but that the complex mechanical mechanism between keys and hammers has been replaced by an electromechanical and electronic system in which all adjustments can be made by computer processing.

• faire que certaines touches, au lieu de commander un marteau unique, commandent de façon sélectionnée un ensemble de marteaux, simultanément ou avec un léger décalage entre eux, pour réaliser par actionnement d'une seule touche un accord complexe ;
• mémoriser les signaux fournis par le clavier 40 pour reproduire le jeu d'un pianiste exactement de la façon dont il l'a effectué, en tenant compte de son toucher spécifique ;
• utiliser un enregistrement pour rejouer un morceau modifié par traitement électronique ;
• varier ou changer la frappe et corrélativement le toucher, par exemple, pour une frappe de touche donnée modifier la frappe du marteau sur la corde ;
• modifier le toucher de façon arbitraire ou pour qu'il corresponde à d'autres instruments à clavier tels que clavecin, clavicorde, orgue, célesta, harmonium ;
• actionner simultanément un synthétiseur d'accompagnement en utilisant les signaux du clavier ;
• régler la course de retour du moteur 35 pour qu'après une frappe de corde, l'étouffoir ne soit réappliqué qu'après une durée déterminée par l'ordinateur.

Of course, if it can use the system according to the invention like a classical piano, it can also be used to perform complex functions, some of which are already performed in synthesizers. For example, by programming, we can:

• make certain keys, instead of controlling a single hammer, selectively control a set of hammers, simultaneously or with a slight offset between them, to achieve by actuation of a single key a complex chord;
• memorizing the signals supplied by the keyboard 40 to reproduce the play of a pianist exactly the way he performed it, taking into account his specific touch;
• use a recording to replay an electronically edited song;
• vary or change the strike and correspondingly the touch, for example, for a given hit, modify the strike of the hammer on the string;
• modify the touch arbitrarily or so that it corresponds to other keyboard instruments such as harpsichord, clavichord, organ, celesta, harmonium;
• simultaneously operate an accompanying synthesizer using keyboard signals;
• adjust the return stroke of the motor 35 so that after a stroke of the rope, the damper is not reapplied until after a period determined by the computer.

Although the invention has been described in the context of a particular embodiment, many variants and modifications will appear to those skilled in the art.

Claims (5)

1. A piano characterized in that it includes, as a means for operating each hammer (2) a first computer-controlled electrical motor/sensor (31) that acts directly on the corresponding motor.
2. The piano of claim 1, characterized in that each key of its keyboard is formed by a flat second modular motor/sensor (40) coupled to a processing system (34) and whose output signals determine, through said processing system, the motion of at least one of said first motors (31).
3. The piano of claim 2, characterized in that it comprises means for storing the sequence of signals generated each time the keys are actuated.
4. The piano of claim 2, characterized in that each first and second motor/sensor is connected to a signal bus (56) of a processor (58) through an output link which comprises a position sensor (50, 63) and an analog-to-digital converter (51, 64) and a return link which comprises a digital-to-analog converter (53, 60) and an amplifier (54, 61).
5. The piano of claim 4, characterized in that the processor (58) is associated with a sampling clock and takes into account the position information of each analog-to-digital converter at each clock pulse and provides feedback information to each digital-to-analog converter at each subsequent clock pulse.

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