EP0121064A1

EP0121064A1 - Keyboard with dynamics control for electronic musical instruments

Info

Publication number: EP0121064A1
Application number: EP84101556A
Authority: EP
Inventors: Umberto Pradella
Original assignee: FARFISA SpA
Current assignee: FARFISA SpA
Priority date: 1983-02-16
Filing date: 1984-02-15
Publication date: 1984-10-10
Also published as: IT1193674B; IT8319616A0; JPS59218496A; AU2466384A

Abstract

This invention relates to a process and means for providing a keyboard of electronic musical instruments with dynamics control. Each key (20), movable between two extreme positions defining two possible states, shifts a mass (23) which can move along a path, defined by a guide. The displacement speed of said mass (23) between two predetermined sights (25, 27) is closely related to the sound intensity from the instrument. Said speed is suitably transduced to cause an output voltage regulating the sound intensity emitted from the frequency and envelope generator device.

Description

This invention relates to a process for providing the keyboard of electronic musical instruments with dynamics control and a keyboard which is improved according to the provided process.
In conventional mechanical type of instruments, a keyboard has two clearly defined operating modes, namely:

- a first operating mode, in which, upon lowering of a key, the generation of a musical sound or note, will occur. The pitch and frequency of said sound or note corresponds to the actuated key, while its intensity is constant or controlled by another means such as, for example, a pedal, knob, blowing apparatus and so on.

Examples of such instruments are organ, accordion, harpsichord.
According to a second operating mode, a sound intensity control is provided, which is proportional, within determined limits, to the key actuating force. This is usually referred to as "dynamics control". The most typical example for this second type of instrument is a piano.
In known electronic keyboard instruments, the operating mode would nearly always be that of said first type. Keyboards are known in which a first type of dynamics control is provided. In such instruments, attempts are made to measure by various devices the speed at which a key is moving between two predetermined sights or determine the pressure being exerted on the key by a finger.
For example, the patent DE-OS-3000646 discloses a key, movable between two extreme positions, at the end of which a mass is firmly attached. The kinematic system of this device is quite different from the one of the known key of a mechanical piano. Thus, during key actuation, the mass and key, as well as the player's finger, hand and arm are simultaneously moving and integrally joined together. Moreover, these types of instruments, besides being costly, do not exactly reproduce the physiological and mechanical sensations provided by a mechanical piano. Therefore, also the technique of performance used is quite different.
It is the object of the present invention to provide a process and device assembly applicable to a keyboard of electronic instruments to obtain a physiological sensation corresponding to that sensed by a pianist playing the mechanical instrument, so as to cause a key actuation with differentiated touch and determine an electrical voltage which suitably controls the amplitude of the acoustical signal on the basis of a voltage output proportional to the strain exerted by the player's finger.
It is an auxiliary object of the invention to provide a device having a reasonable cost, so as to be bought by many users.
The object is achieved by providing, in a keybord having each key movable between two extreme positions defining two possible states, that the speed at which a mass provided for each key moving between two predetermined sights is measured, then said speed is transduced into an electric signal which, as suitably processed, is supplied to the sound and envelope generating device, to control a voltage output determining the desired sound intensity, characterized in that said mass is initially displaced by the key actuation, is separated therefrom and freely moves along a predetermined path, while the key, after having struck the mass, will go back again to the initial position, independently of the mass position at that time.
An improved keyboard according to the process provides a number of keys, each of which pivoted at a determined location, transducer means for transducing the key displacement speed into an electric quantity, information processor means, and a sound and envelope generating device, in which said transducer means have a whole mass as that of the mechanical elements provided for each key in a normal piano, said mass being movable between two extreme positions along a predetermined path, a switch means being arranged at each of said extreme positions to supply to the processor means electric signals relating to the instants at which said mass contacts said switches.
In order to reduce the implementation costs for said device, it is provided that said processor means further comprise a device effecting a periodical scanning on the state of the switches arranged at the extreme ends of the mass stroke
An improvement to the key unit contemplates the provision for each key of a retainer element for holding the key in place at its rest or inoperative condition.
A particular approach or embodiment further contemplates that for the two extreme positions of the mass a first set of normally open contacts and a second set of normally closed contacts are provided.
A particular embodiment provides that said mass is made of conductive metal material to make up the movable contact for the switches provided at the extreme positions.
An approach or embodiment provides that said retainer element is made of magnetic rubber.
Finally, the mass guide means may provide either a straight path or comprise a pin for rotation through a predetermined angle.
The basic characteristics of the present invention will now be illustrated with reference to the accompanying drawings, in which:

Fig. 1 is a view schematically showing the mechanical part normally provided in a mechanical piano;
Fig. 2 is an embodiment showing the mechanical and electric parts of a keyboard according to the invention, in which the key is at rest position;
Fig. 3 is the embodiment of Fig. 2 at the position in which the key has been operated;
Fig. 4 is another embodiment of the mechanical part; and
Fig. 5 is a block diagram for the circuit.

The invention herein described is aimed to propose for the mechanical part a series of kinematic motions corresponding to the moving parts in a classical mechanics for a piano and for the electronic part a measuring arrangement providing the information required for the control of the amplitude of a sound generated by a known frequency and envelope generator.
Fig. 1 is a view schematically showing the classical mechanics of a piano. It is seen, according to this figure, that, upon actuation of key 10 pivoting about fulcrum 11, a movement is provided for the hammer 12 which, in its rotation about the pivot 13, will strike the string 14. Coupling between the two movements is provided by the escapement 15 which, by rocking or swinging about the center 16, transmits the pulse from the key to the harnner for disengagement just before the latter reaches said string 14. The strain sensed by the pianistis is not constant. Thus, following an idle stroke, that is, until the projection of hammer 12 is touched, a substantial strain is exerted to overcome the system inertia until the escapement is disengaged and the finger does no longer sense any strain, while the hammer accelerates to maximum rate, continuing its stroke owing to inertial forces.
Figs. 2 and 3 are views showing an embodiment for the mechanical and electrical parts of a key in a keyboard according to the invention, having the purpose of reproducing this situation. By rotating about the fulcrum 21, the key 20 will strike with its extending portion 22 against a small cylinder 23, made of conductive metal, such as iron, and the mass of which is closely equivalent to that of the escapement and hammer of a conventional mechanics. This small cylinder 23 bears against the key at rest or inoperative position (Fig. 2). The small cylinder 23 is retained at said rest or inoperative position by the magnetic action of a bar 24, made of magnetic rubber, performing retainer and shock absorber functions to reproduce the inertial situation of classical mechanics. Said small cylinder 23 also bears on the electrical contact 25, thus providing a switch with normally closed contacts at rest or inoperative condition.
Upon pulse reception from the movement of extension 22, said small cylinder 23 freely upward moves along guides 26 to close the electric contact 27 of a switch having normally open contacts. The seat provided in said guides 26 allows a straight or rectilinear path. After having pushed the small cylinder, the key 20 separates therefrom, and terminates its stroke arresting against a stop (not shown) to then go back to initial position, where it will be maintained at steady position by said magnetic bar 24 and small cylinder 23.
When indicating by M the mass of the finger and arm portion cooperating in key operation, by V the speed thereof, by m the hammer mass and by v the speed thereof, the following relation exists:
which is maintained by the solutions of Figs. 2, 3 and 4, since the small cylinder mass m is equivalent to that of the escapement and hamer. Therefore, the physiological sensation sensed by the player will be equivalent to that provided by a normal piano.
Another embodiment is shown in Fig. 4. It also provided a mass freely movable along a predetermined path under the pulse given thereto by the key operated by the player. According to this approach, the operated key 120 rotates about the fulcrum 121 and by its extending portion 122 strikes a mass 123 pivoted at 126.
The mass 123 may be made of conductive metal, for example iron, and is equivalent to that of the escapement and hammer for a conventional mechanics. The mass 123 is maintained at rest or inoperative position by a magnetic element 124, made of magnetic rubber, also forming a damping and braking element for the mass during transports and displacements. An extension 123a of said mass 123 bears against the electric contact 125, making up a switch with normally closed contacts. On receiving the pulse from the extension 122, said mass 123 rotates about the guide pin 126 to reach the hatched position, thereby closing the contact 127 of a switch having normally open contacts. Also in this case, when struck by said mass 123, the key 120 is separated therefrom and at the end of the stroke thereof goes back to the initial position.
However, since the mass in both cases is identical, the measure or value of the small cylinder speed is proportional to the sound intensity corresponding to the speed given by the player. The second part of the invention relates to way to convert said speed into an electric control signal.
Thus, still considering the key 20 or 120 of Fig. 2 or Fig. 4 with the relative masses 23 or 123, it will be seen that the electric circuit between the contact 25 or 125, the body of mass 23 or 123, and the guide 26 or pin 126 made of electricity conductive material can be closed when the key, and accordingly the relative mass, are at rest or inoperative condition. When the mass has completed its stroke and reached the hatched position as pushed by the key, it will close the electric circuit between the contact 27 or 127 and the conducting guide 26 or pin 126. These two signals are sensed by a digital electronic counter 29 or 129 and -converted into an electric voltage through a digital/analog converter D/ A 29a or 129a.
Let us consider the number of fingers that at a same time can operate the keys: these at maximum may be ten, or twenty, when playing four-handed. Therefore, an operation in polyphony of ten or in polyphony of twenty could be provided.
Hereinafter reference will be made to the polyphony of ten, it being however evident that the same circuit is also applicable to a polyphony of twenty.
Fig. 5 shows a preferred embodiment for the circuit of the simplification above set forth. Such an embodiment provides the use of a microprocessor device 30 having CK and P. OR as inputs. It carries aut a very fast scanning on the matrix of the normally closed contacts (block 31 ) associated with the switch with normally closed contacts comprising the mass 23 or 123 and the contact 25 or 125, and on the matrix of the normally open contacts (block 32) comprising the mass 23 or 123 and the contact 27 or 127 through a decoder 33 for the selection of the common bars and a matrix of diodes 34.
Since it is not humanly possible to actuate two consecutive notes in a time less than 1/200 sec and that normally 88 keys are provided on a keyboard, it will be seen that in conmercially available microprocessor devices the scanning speed or rate is quite consistent with these quantities.
The data for the keyboard are then read by the microprocessor element 30 which, after suitable processings, will transfer such data to a number of output gates. A portion of these is connected through a cannon channel ( or bus) 35 to the peripheral sound and envelope generator device 36, which in turn is controlled by a timer 37 and T.O.S. 38. The remaining portion is connected through suitable decoders 39 having as many "n" counters 40a-40n as the keyboard polyphony channels (n). More particularly, each output of decoders 39 is for conditioning the positioning controls (set and reset) of the respective counter 40a-40n, which will be gated as soon as the normally closed keyboard contact scanned by the microprocessor opens, and the counting operation will be stopped when closing the normally open contact located at the final positioon of the stroke for the corresponding mass.
The number or digit in each counter, connected to clocks 41a-41n at the time of closing for the end of stroke contact, is the numerical value ( as suitably inverted) corresponding to the transition time for the mass between the two extreme positions and therefore will be directly proportional to the switching time of the contact.
Such a value is then stored in registers 42a-42n in order that the information is not lost for all the time the key is actuated or played, and converted through a suitable digital-to-analog converter (D.A.C.) 43a-43n. The output voltage fran said digital-to-analog converter is inputted to the corresponding voltage controlled amplifier (V.C.A) 44a-44n, and to a voltage controlled filter (V.C.F. ) 45a- 45n, which is connected to the sound channel assigned on the frequency and envelope generator peripheral through a mixer 46 and amplifier 47.
Thus, an economical and dynamic amplitude control can be provided and quite corresponding to the tactile and auditory sensations for a-player as normally provided by a mechanical piano.

Claims

1. A process for providing a keyboard of electronic musical instruments with dynamics control, in which each key (20, 120) is movable between two extreme positions of a predetermined stroke, defining two possible states, wherein the speed by which a mass (23, 123) moves between two preset sights is measured, which mass is moved by the operation of said key (20, 120) said speed is transduced into an electrical signal which, suitably processed to provide a voltage related to the displacement speed of said mass (23, 123) is supplied to the sound and envelope generator device (36), characterized by the fact that said mass (23, 123) is initially displaced by the operation of said key (20, 120), is separated therefrom and freely moves along a predetermined path, while the key (20, 120), after having struck the mass and reached an end of stroke position, goes back to the initial position independently of the position where said mass (23, 123) is at that time.

2. An improved keyboard comprising a series of keys (20, 120), each of which is pivoted at a determined location (21, 121 ), transducer means (23-25, 26, 27, 123-125, 126, 127) for transducing the key displacement speed into an electrical quantity, information processor means (42, 43, 44, 45) and a sound and evelope generator device (36), wherein said transducer means comprise an equivalent element or equivalent mass (23, 123) movable between two extreme positions, at each of which switch means (25, 26, 27, 125, 126, 127) are provided to supply a processor means with electric signals relating to the manents in which said mass contacts said switches, characterized by the fact that said equivalent element or mass (23, 123) has a whole mass like the one of the mechanical elements comprised in a normal piano, is separated from the key (20, 120) and is freely movable along a predetermined path by guide means (26, 126) under the pulse given thereto by said key (20, 120).

3. An improved keyboard as claimed in Claim 2, characterized by the fact that said processor means comprise at least one electronic counter device (29, 129) for receiving at the input thereof the signals supplied by said switches, thereby to process data in digital form relating to the mass displacement speed.

4. An improved keyboard as claimed in Claim 2, characterized by the fact that said processor means comprise a device (30) carrying out a periodical scanning on the state of the switches provided at the extreme ends of the mass stroke, thereby reducing the detecting circuitry associated with each key.

5. An improved keyboard as claimed in Claim 2, characterized by the fact that each key (20, 120) provides a retainer element (24, 124) to maintain said key at its rest or inoperative condition.

6. An improved keyboard as claimed in Claim 2, characterized by the fact that said switch means provided at the extreme end of the mass stroke comprise normally closed contacts (25, 26, 125, 126) and normally open contacts (26, 27, 126, 127), that is with rest or inoperative conditions in opposition to one another.

7. An improved keyboard as claimed in Claim 5, characterized by the fact that said mass (23, 123) is made of electrical conductive metal material, thereby to form the movable contact of the switches provided at the ends of stroke.

8. An improved keyboard as claimed in Claim 5, characterized by the fact that said retainer element (24, 124) comprises magnetic rubber.

9. An improved keyboard as claimed in Claim 2, characterized by the fact that said guide means (26) for providing the path of said mass (23) provides a seat for enabling the mass to move in rectilinear direction.

10. An improved keyboard as claimed in Claim 2, characterized by the fact that said guide means (126) for providing a path for said mass (123) comprise a pin about which the mass (123) rotates through a predetermined angle.