WO1989002640A1

WO1989002640A1 - Optical recording device for the striking of a piano key

Info

Publication number: WO1989002640A1
Application number: PCT/FR1988/000444
Authority: WO
Inventors: Eric Lamy; Denis De La Rochefordiere
Original assignee: CAYREL, André; GUERAND, Gérard
Priority date: 1987-09-09
Filing date: 1988-09-09
Publication date: 1989-03-23
Also published as: FR2620255A1; AU2425888A; FR2620255B1

Abstract

The invention relates to devices for accurately recording the striking characteristics of a key of a keyboard, particularly a piano keyboard, and in order to use and exploit such recording. An essential object of the invention is therefore to provide a device for recording the striking characteristics of keys of a keyboard, said device making possible the faithful reconstitution of all touch forms practised on a string piano, and a device for making use and exploiting such recording. This object is reached by means of an optical recording device characterized in that it is provided with a displacement indicator (30) mounted integral on the key (31), said indicator (30) being provided with a plurality of graded marks along the key displacmenent direction, and with a displacement sensor (3) for detecting the displacement of said indicator (30), the sensor comprising means for detecting the passage of said marks during the displacement of the indicator (30). The invention applies preferably to digital pianos.

Description

Optical device for recording the striking of a piano key.

The field of the invention is that of devices making it possible to record, in a precise manner, the typing characteristics of a key on a keyboard, in particular a piano keyboard. The purpose of carrying out such a survey is in particular to allow the synthetic reconstruction of the sounds of a string piano using a digital piano. It also makes it possible to make available to the user or the artist a range of several "keystrokes" distinct from the keys, producing different effects.

The invention finds a preferential application for digital pianos, and provides the various components of the sound production chain from the recording of the typing characteristics of the keyboard to the sound emission.

However, some of the constituents of the invention are also immediately transposable into neighboring fields, obvious to those skilled in the art. As a simple example, mention will be made of keyboards for 1 "" orchestration "of light games, games of water jets, video synthesis means, etc.

Electronic keyboards are already known provided with devices for recording keystrokes.

Apart from simple hit detectors, based on all-or-nothing microcontacts or the like, there is in particular a device for detecting the strike force exerted on a key as illustrated in FIG. 1. To know the strike force exercised on the key, the sensor calculates the time taken by the flexible blade 10, integral with the key 11, to go from one electrical contact 12 to the other 13.

However, these devices have not only mechanical operating disadvantages, but also very significant shortcomings in terms of the accuracy and quality of the survey carried out.

In the order of mechanical drawbacks, it may be noted the difficulties of adjusting the movable flexible blade 12 with respect to the fixed contact 12, 13, the risks of oxidation or smearing of the contact points between the blade 10 and the contacts 12, 13, and in general all the risks of misadjustment, deformation and wear associated with the intense use of a fragile mechanical device. More essentially, the survey carried out only allows a very summary interpretation of the typing characteristic of the keys. Indeed, only one parameter is noted, namely the speed of movement of the key between two predetermined points. However, to regain the touch of the piano, it is in particular necessary to allow the artist to muffle and reset a note, possibly repetitively, at different depressing positions according to the acceleration of the key. This known device then becomes inoperative.

Also known, from US Patent No. 4,307,648, is a method and apparatus for evaluating characteristics of a conventional acoustic piano for mechanical reproduction. To this end, there is provided a shutter playing the role of witness, or two witness shutters are provided, for displacement, mounted on the handle of the hammer; when there is only one witness, it is provided (or not) with a single notch; one or two witness displacement sensors are also provided. comprising means for detecting the passage thereof and possibly the notch; in this latter hypothesis, a clock delivers counting pulses from the detection of the passage of one end of the indicator until the detection of the passage of the second end of the notch.

As a result, the subject of this document necessarily involves mounting on an acoustic piano since many other keyboard devices and in particular digital pianos do not include a hammer or hammer handle; moreover, the fact that the witness is on the handle of the hammer only imperfectly accounts for the keystroke, because this very "downstream" location is influenced by all the parasitic parameters which are introduced after the keystroke the fingerboard (such as mechanical play, wear of the hammer felts and possible repetition failure, for example); insofar as these parameters change over time, the reading taken is different for two identical keystrokes, and the user will not obtain the same sound for two keys; moreover, the reading depends on the mechanical adjustment of the piano made for each note.

In addition, the principle of the measurement (start of counting signal and end of counting signal) limits the possibilities of interpretation and remains integral with the mechanical adjustment of the piano used.

The objective of the invention is in particular to overcome all of the drawbacks and limits of these existing devices.

More precisely, an essential objective of the invention is to provide a device for recording the typing characteristics of the keys of a keyboard which allows the faithful reconstruction of all the forms of touch practiced on string piano. However, the sophistication of the recording device allowing such fidelity of reproduction must also be able to allow the application of the invention to be widened, for example for the creation of new touch characteristics and / or the production and creation of other types of sounds .

A complementary objective of the invention is to provide a device for recording and producing sounds in which no perceptible delay must be felt between the pressing of a key and

10 the appearance of sound, whatever the strike.

Another complementary objective of the invention consists in simulating the operation of the hammer in string pianos, by providing a device which allows a note to be played.

15 triggered by the acceleration effect produced on a moving key, when the latter has not yet reached the end of its previous stroke.

Another object of the invention is to provide a device which simulates the function of

20 the damper in string pianos, allowing a pressed note to be released two-thirds or halfway without choking. The intervention threshold for the damper, if applicable, must be adjustable.

An additional objective of the invention is to provide a reading device which is of a low cost price, and of a high reliability and resistance to wear.

The invention also aims to

30 provide a device for synthetic reconstruction of sounds which takes account of the characteristics recorded from the striking of each key for the production of a corresponding sound according to a given intensity, waveform and harmonic richness. Advantageously,

³⁵ . the invention must also be capable of being the subject of a "reprogramming" to modify the sounds associated with each type of keystroke.

Another objective of the invention is to provide a complete production chain of musical sounds from a keypad provided with the recording device of the invention, and allowing the production of all types of complex chords, sequences with notes held, notes pitted, muffled, repeated, trills and tremolos obtained on string pianos, with reconstruction of the attack of each note, its outfit, and its extinction as faithfully as possible.

These objectives, as well as others which will appear subsequently, are achieved with the aid of an optical recording device, in particular for recording the characteristics of movement of a key hit on a keyboard, of the type of piano keyboards. or the like, characterized in that it is provided with:

a displacement indicator mounted integral with the key, said indicator being provided with a plurality of marks staggered according to the direction of displacement of the key, and

- A displacement sensor of said witness, comprising means for detecting the passage of said marks during the displacement of the witness.

Advantageously, said indicator consists of a transparent support carrying a set of opaque bars staggered according to the direction of movement of the key, said indicator scrolling between a light source, visible or not, and an optical sensor for moving the indicator. during the striking of the associated key, so that the passage of said opaque bars in front of the light source ensures the interruption and the restoration of the beam light from the light source and received by said optical sensor.

According to another characteristic of the invention, said optical sensor is a logic sensor providing at the output a crenellated signal, capable of taking two alternating states:

a first state when the beam of captured light has a brightness greater than a predetermined threshold;

a second state when said beam of captured light has a brightness lower than said predetermined threshold.

The objectives of the invention are also achieved by means of a device for analyzing and exploiting the displacement information provided by the optical reading device described above, characterized in that it includes means adapted to determining the direction of movement, the turning back during the race, the speed and the acceleration of movement of said hit key.

In a preferred embodiment of the invention, said device for analyzing and exploiting the displacement information provided by said optical reading device in the form of a crenellated signal with two states comprises Ï - means for detecting the 'attack of the button;

- means for determining the attack characteristics of said key;

- means for detecting the release of the key;

Advantageously, when the output signal from the optical reading sensor consists of a succession of high and low pulses, the said means for detecting the attack of the key are made Î - means for memorizing the duration of each of the high and / or low pulses;

means for recognizing the end of the forced striking stroke of said key when the ratio of the comparison of the duration of the current pulse with the duration of the previous pulse and / or a reference pulse duration exceeds a predetermined threshold.

Advantageously, said means for determining the striking characteristics of each key consist in carrying out a selection and / or equalization operation between said durations of the pulses. The selection may for example consist in retaining only the smallest of the pulse durations measured or else the last pulse duration immediately preceding the recognition of the end of the forced strike stroke. The striking characteristics thus determined then cooperate, in the case of an application of the invention to an electronic piano, with means for producing an attack sound corresponding to the noted striking characteristic. Advantageously, it is possible to provide at least two different attack sounds per key, or even more, depending on whether the pulse duration and / or the speed at which the key is struck falls within a predetermined range of values. .

According to another characteristic of the invention, said means for detecting the release of the key comprise: means for recognizing and memorizing an initial state of effective depressing of the key;

means for memorizing the duration of each high and / or low pulse of the crenellated output signal of the optical reading sensor; 8

means for recognizing the limit switch free to release the key when the ratio of the comparison of the duration of the current pulse with the duration of the previous pulse and / or a reference pulse duration exceeds one predetermined threshold.

Advantageously, and in order to simulate the behavior of a string piano, the release of the key is accompanied by a forced attenuation upon detection of the release of the key (approach of the damper against the resonant string) , to which is added a "reinforced" attenuation when recognizing the end of the free run to let go of the button (complete application of the damper on the resonant string to cause the total extinction of the sound). During the application of the invention in particular to the production of an electronic piano with digital synthesis of sounds, the device for analyzing and exploiting the movement information provided by the sensor for optical reading of the keystroke characteristics is characterized in that it comprises:

means for detecting the keys struck, preferably comprising means for calculating for each key the typing characteristics, means for cyclically scanning all of the keys with identification and selection of the keys activated since the previous scan, and means for memorization of the typing characteristics of said activated keys; means for producing an attack sound comprising a memory for storing at least two sampled attack sounds for each key, said memory being addressed by means of selecting the attack sound as a function of the key struck and in function of the attack characteristics of said key;

means for producing a holding sound extending said attack sound, constituted by a memory for storing at least one sampled holding sound for each key, addressed as a function of each key struck and if necessary as a function attack sound when several holding sounds are provided by touch • _e; means for attenuation and / or over-attenuation of said sustaining sound as a function of envelope information in waveform intensity, duration and attenuation coming from an envelope compilation module, as a function of the typing characteristics of each activated key. In a preferred embodiment, said means for memorizing the typing characteristics of the activated keys only have a limited capacity of. memorization, and ensure the expulsion of one of the memorized keys; the criterion for choosing said expelled key advantageously belongs to the group of criteria comprising the choice of the oldest key played, the choice of the key whose current note is the weakest in intensity, and the choice of the highest note. Advantageously, said device for electronic piano with digital sound synthesis comprises a sound emission unit consisting of a polytimber synthesizer receiving as input on the one hand the sampled waveforms of the attack sounds and of maintaining from said memory sampled sounds, ^'and secondly an envelope information from said compiling characteristics keystroke module.

Other characteristics and advantages of the invention will appear on the following reading of the description of preferred embodiments of the invention, given without limitation, and attached drawings in which: Figure 1 shows schematically the prior device discussed in the preamble; FIG. 2 represents a preferred embodiment of the optical indicator with opaque bars of the optical reading device according to the invention;

- Figure 3 shows schematically a preferred type of mounting of the indicator of Figure 2 on a keyboard key;

- Figure 4 is a diagram illustrating, in the general case, the shape of the signals representative of the keystroke characteristics, as read and calculated from said optical reading sensor of the invention;

- Figure 5 is a diagram of the type of Figure 4, illustrating the speed of response times of the means of processing the signals from the optical sensor according to the invention;

- Figure 6 is a diagram of the type _. of Figure 4 illustrating the simulation of the damper control in an electronic piano provided with the device of the invention; FIG. 7 is a diagram, of the type of FIG. 4, illustrating the behavior of the devices for reading and exploiting the striking characteristics of the keys during a repetition of a key attack;

FIG. 8 is a diagram of the type of FIG. 4, illustrating the behavior of the devices for reading and exploiting the characteristics of the keystrokes according to the invention, in the event of a key attack of the "pitted note" type ;

- Figure 9 is a schematic diagram representative of the output signal from the reading sensor 11

optics according to the invention, illustrating the range of precision and sensitivity of said sensor;

- Figure 10 is a block diagram of an embodiment of a digital piano provided with devices for reading and exploiting the typing characteristics of a keyboard key according to the invention;

- Figure 11 is an electronic block diagram of an embodiment of an optonumeric module mounted at the output of the optical reading sensor according to the invention for obtaining useful signals representative of the typing characteristics of the keys;

- Figure 12 is a simplified diagram illustrating an embodiment of the connections between the different modules constituting a digital piano provided with a device according to the invention;

- Figure 13 is an illustrative diagram of the management means of a keyboard with 88 keys, each key being provided with an optical reading device of the typing characteristics according to the invention;

The design of the device for optical reading of the typing characteristics of a key keyboard according to the invention is the result of an in-depth analysis of touch and the rendering of sounds in a classical string piano.

Two types of considerations should be taken into account during a detailed analysis of touch:

- the mechanical behavior of the chain of elements connecting each key to the corresponding set of strings, in a classical string piano; the characteristics of the sound spectrum rendered by the strings as a function of touch.

Among the essential elements of the mechanism of transmission of the touch to the strings, we must note the important role played on the one hand by the hammer 2640

12

strings, and on the other hand by the felt of suffocation of the resonance of the strings struck. The function of the hammer is to cause the keys to be struck only when a certain penetration threshold and / or a certain speed for striking a key are crossed. In addition, the intensity of the note rendered depends closely on the force of the hammer, which is itself linked to the speed at which the associated key is pressed. In addition, the so-called "double escapement" system in advanced grand pianos allows rapid repetition of notes, even if the key has not been released completely. After striking, each struck string first undergoes natural damping of the vibration, which is then greatly attenuated when the damper is applied to the strings. The damping action and effect of the damper can be controlled by temporarily holding the button in the fully depressed state, then by the speed of release of the button.

The role of harmonic pedals will also be noted for memory, an important improvement of which is the subject of patent application no. 86 08177 filed by Denis de la ROCHEFORDIERE, also co-inventor of this patent.

With regard to the spectrum of the sound rendering of the strings as a function of touch, you should know that, in a classical string piano, the sound obtained is richer in harmonics during a "strong" and "fortissimo" touch, than when touching "piano" or "pianissimo". This effect is due to the phenomenon of sympathetic resonance of the whole plane of strings, which increases with the speed of striking the hammer, and the greater compaction of the felt of the hammer.

It therefore follows that the touch of the pianist is an essential parameter controlling the rendering of the sound. Sometimes seen by the layman as an obstacle to be overcome. on the contrary, touch is a fundamental characteristic of the piano game, the mastery of which characterizes the quality of the artist. In addition, we may note a preference of some performers for pianos to touch "soft", or "hard", these characteristics may vary depending on the invoice of the instrument. One of the objectives and advantages of the invention is to authorize an adjustment of the response (threshold and sensitivity) of the electronic piano to the will of the pianist, with possibly (adjustable) simulation of the mechanical resistance of the keys.

In a conventional device for recording the striking characteristics, such as the prior device in FIG. 1, only the intensity of the sound rendered is controlled by touch. On the contrary, in the invention, are controlled continuously by means of each key, not only the intensity of the sound rendered, but also its richness in harmonics and its timbre, its attack characteristics, as well as the attenuation characteristics and switching off the sound as a function of the release button.

These objectives are achieved using an optical reading sensor of the type shown in FIGS. 2 and 3.

The present description of a detailed embodiment of the invention is specifically linked to the application of optical reading devices and of exploitation of the striking characteristics of a key, and to the realization of an electronic piano with • digital synthesis of sounds. Of course, the scope of the invention is not limited to this embodiment, and extends to all types and possible uses of keyboards, as already mentioned in the preamble.

In the embodiment of Figure 3, the displacement indicator 30 is mounted at the end of 02640

14

the articulated key 31, so as to come between an optical source 32 and an optical reading sensor 33.

Advantageously, the indicator is mounted at the end of the key 31 opposite the striking end F, so as to benefit from the precision conferred by the lever arm at the point of rotation 35.

When the key F is pressed, the indicator 30 moves in the direction of "driving" E in front of the sensor 33. When released, the direction of movement L of the indicator 30 is reversed.

If necessary, a second sensor 34 can be provided, for managing an over-depressing effect of the key. This overpressure effect may possibly be desired in order to obtain a tremolo, a vibrato, or the like. An equivalent means consists in providing a fourth zone with opaque bars on the indicator 30 as shown in FIG. 2.

Advantageously, the indicator 30 in FIG. 2 is formed by a transparent ylar plate on which opaque bars 21 have been affixed, as well as an extended opaque zone 22. These marks are distributed over a range 1 of reading, corresponding to the approximate travel of displacement of the indicator 30 during a complete hitting of a key. Track 1 can be broken down into three zones crossed successively when the witness moves in the E or L direction:

- A first transparent zone A, corresponding to the rest position of the key; - A second zone B comprising a plurality of opaque bars - 21 substantially parallel, and spaced along the direction of movement E, L of the key and corresponding to the central part of the stroke of movement of the key; 15

- A third opaque zone 22 corresponding to the pressed position of said button.

The scrolling of the indicator 30 in front of the sensor 33 makes it possible to obtain at the output of the sensor, if necessary after preliminary processing (circuit of FIG. 11), a crenellated "code" signal referenced 23 in FIG. 2. The passage of the light to through a transparent zone corresponds to the zero state (low) of the crenellated signal, and the interruption of the light beam corresponds to state 1 (high).

Zone B of the indicator 30 carrying the parallel opaque bars 21 may advantageously, but not necessarily, have from 2 to 10 bars, preferably 3 bars. The multiplication of the number of bars 21 improves the measurement accuracy, as well as the ability of the optical reading device according to the invention to respond faithfully to key depressions before complete release, re-accelerations of keys during depressing, and to all type of hitting repetitive.

In the embodiment shown, the width of the bars 21 is substantially equal to the interval separating two adjacent bars. However, depending on the desired effects, the characteristics of the sensor 33 used, and the characteristics of the signal processing circuits supplied by the sensor 33, it will be possible to envisage using bars of different widths (linearization of the responses, threshold effects ...).

The multiplication of the number of opaque bars 21 also has the advantage of making it possible to obtain a plurality of values when the key is moved. This plurality of values makes it possible on the one hand to calculate a value for acceleration of the key, and on the other hand to detect possible errors of reading due for example to the presence of dust inadvertently blocking the light beam received by the sensor 33.

FIG. 9 illustrates the range of precision and sensitivity of the sensor, which has been chosen so as to be able to detect pulses of durations ranging from 100 microseconds to 200 milliseconds. These values were noted and experimentally optimized on prototype. The corresponding indicator has bars of approximately 0.3 mm. In a preferred form of implementation of the invention, this scale makes it possible to define an accuracy of 4096 steps on 12-bit words, the ratio of minimum and maximum speeds after processing being at least equal to 1/1000. The sensor according to the invention therefore allows considerable precision, and allows an extremely fine and faithful touch analysis and sound rendering, without common measure with existing devices.

In an advantageous embodiment, each key is associated with members 100 of adjustable mechanical resistance to striking and pressing, and / or members 100 for returning the key to the rest position so as to simulate the conditions of touch on string piano.

FIG. 4 is a diagram illustrating, in the general case, the shape of the signals representative of the keystroke characteristics, such as readings and calculated from the optical surveyor sensor of FIG. 2.

This diagram is made up of 4 distinct signals: - a "code" signal obtained on 1 bit at the output of the optical reading sensor, possibly after preliminary processing described below with reference to FIG. 11; ^'

- a signal "dyn" dynamics, consisting of ^'words of 12 bits representative of the duration of 17

each "low" and "high" pulse of the "code" signal. Of course, the length of the word mentioned does not constitute a limiting characteristic of the invention.

- a "spoiling" signal, on 1 bit, representative of a key validation information, which passes to the validated state upon recognition of the end of the forced key stroke, until recognition of the limit switch free to release said key;

- an "atten" signal, on 1 bit, representative of attenuation information which is activated during recognition of the end of the forced stroke of the key, until the start of a free stroke is detected to let go of said key.

As already mentioned with reference to FIG. 2, two types of pulses can be distinguished in the crenellated "code" signal, namely pulses of low level 41, 43a, 43b, 43c, 45a, 45b, 45c, 47, and high level pulses 42a, 42b, 42c, 44, 46a, 46b,

• 46c. In the sequence shown, the key successively undergoes four distinct phases Ï

a phase 1 of attacking the key, in which the rapid passage of the indicator 30 in front of the optical sensor 32 causes a succession of high pulses 42a, 42b, 42c and low pulses 43a, 43b, 43c corresponding respectively to the passage of opaque bars 21 and intervals between opaque bars.

a phase 2 of prolonged depressing of the key, in which the “code” signal is in the “high” continuous state 44, due to the complete blocking of the light beam by the extended bar 22 of the indicator 30;

- a phase 3 of releasing the key, in which the succession of low pulses 45a, 45b, 45c and high pulses 46a, 46b, 46c corresponds to the passage of opaque bars 21 in front of the sensor 32, in the opposite direction to that of the attack phase A; a phase 4 corresponding to the stabilization of the key in the rest position, with continuous maintenance of the "code" signal at zero level 47, 41.

The signal "dyn" 50 corresponds to the emission of words representative of the duration of each of the pulses. In the version produced, the duration calculations relate to the zero level pulses 43a, 43b, 43c, 45a, 45b, 45c and 47 as well as to the pulse 44 of prolonged penetration. Of course, it is also possible to selectively record the duration of the high pulses or even the duration of all the high and low pulses. Signal "spoils" 60 goes from zero state

(low) in state one (high) when recognizing the end of the forced key stroke. This is advantageously achieved when it is noted that the high level pulse immediately following a low level pulse 43a, 43b, 43c extends over a duration ₂ greater than twice the duration t ₁ of said low level pulse. In the diagram of FIG. 4, this case occurs only after the pulse 43c, and is noted after the duration ₂ = 2- ^ c immediately following the pulse 43c of low level and duration t- ^ C.

Symmetrically, the reverse passage of the “spoils” signal 60 from the high level to the low level is controlled when the sensor detects a low pulse of duration t ₄ at least equal to 2 times the duration of the immediately preceding measured pulse. In the diagram of FIG. 4, this condition is only realized when the "code" signal 47 is detected immediately following the low pulse 45c of duration t ₃ c. Of course, the multiplier "2" recommended does not constitute a limiting characteristic of the invention.

The signal "spoils" 60 has the function on the one hand, of recognizing the end of the attack zone of the key struck, in order to proceed with the determination of the attack sound to be produced. as a function of the durations t ₁ a, t ₁ b, t ₁ c memorized as will be seen below, and on the other hand to carry out an "enhanced" attenuation of the signal when the end of the free travel has been detected. let go of the button. This reinforced attenuation must be able to cause the total extinction of the sound within a range of 2 ms at 500 s (value possibly adjustable) so as to simulate a natural break.

The "atten" signal 70 goes from low level to high level under the same conditions as the signal

"spoils" 60. On the other hand, this signal returns to zero level upon detection of the release of key 71, as will be seen in detail below.

FIG. 5 illustrates the rapidity of the response time of the optical reading device and of the operation of the keystroke characteristics according to the invention. In this diagram, it is noted that the attack pulses 51 supplied by the "code" signal 40 have short durations, which schematically corresponds to a strong attack which must provide a note of high intensity, and rich in harmonics. In this case, the “spoils” signal 60 very quickly passes to level 1 (52), the duration t2 = 2t ₁ being short. Conversely, in the case of a less intense typing, the response time would be longer, which corresponds to the reality in classical string pianos.

Figure 6 shows the four signals "code" 40, "dyn" 50 and "atten" 70, in the case of a note held, even slightly shaky, without letting go. This 20

case corresponds to the retention of the damper in a classical string piano, by roughly holding the key down.

Despite the existence of a pulse t _A , t _β in the crenellated "code" signal 40, the "spoils" signal 60 does not return to zero level. This is due to the fact that at no time does the detector detect end-of-stroke recognition free to release a key (t ₄ > = 2t ₃ ; see fig. 4).

On the other hand, the "atten" signal 70 undergoes some variations, and returns to the zero state each time that a low pulse 62, 64 follows a prolonged high pulse 61, 63 symptomatic of a depressed holding of the key. Conversely, each passage of the "code" signal 40 to an extended high level 61, 63, 65 following a short low pulse t _j , t _A , t _B , causes the "atten" signal 70 to rise to the high level.

The trembling observed on the key by the succession of slots of the “code” signal 40 does not, however, cause a repetition of the note, unlike in the case of FIG. 7. In fact, as will be seen below, the signal “code” "40 of FIG. 6 does not verify the necessary condition, namely the fact that the duration t _A , t _B of the crenellated secondary sequences of the signal" code "40 is smaller than the duration ^ of the initial attack pulses of the touch.

The “code” signal 40 of FIG. 7 is representative of a succession of releases and of re-attacks of a key, the re-attack being carried out even before the key has returned to its rest position. The re-emission, note command is carried out by the passage of the "spoils" signal 60 from the zero state to the state 1, at 76, 77, ....

The variation of the “spoiling” signal 60 is only carried out when two conditions are met: - the key re-attack pulse t ₂ is less than less than half the duration of the preceding pulses;

- the zero level pulses t ₂ , t ₃ , t ₄ for re-attacking the keys are followed by a high pulse of at least double duration (confirmation that the key has been pressed).

In all the cases illustrated in FIGS. 4 to 7, the reference pulse, for each train of almost identical pulses (attack phase, or release phase) is the pulse of minimum duration. However, it is also possible to choose a reference pulse duration corresponding to the last memorized pulse, or even to an equalization calculation carried out over all the durations t- ^ A, t ₁ B, t _{j ^} C, etc., memorized during the same phase.

It will also be noted that, in the diagrams represented, the “atten” signal 70 does not systematically anticipate a return to zero of the “spoiling” signal when it returns to the low level (see FIG. 6). Indeed, the "atten" signal, control the simulation means of the damper ^• 1'approche against the (or the) rope (s) resonant (s), as skilled pianist can control. On the other hand, the “spoils” signal controls the total and rapid extinction of the sound corresponding to the complete application of the damper.

The diagram in Figure 8 corresponds to the case of a stitched note.

We recognize in the "code" signal 40 a phase 81 of attack, followed by a phase 82 of letting go of note, this phase 82 of letting go intervening before prolonged pressing of the key, and therefore before the ^' end of race'. pressing said key (no prolonged pulse 44 as in FIG. 4).

However, since the ascent of the key is always performed more slowly than pressing, the key ascent is never forced, the first high pulse 83 of the release phase 82 has a duration significantly greater than twice the duration t ^ of the pulse representative of the attack phase 81. As a result, the system correctly performs recognition of the end of the forced attack stroke of the key, and controls the passage of the “spoiling” signal 60 to the high level (84).

If the key had been pressed again, before recognition of the free run limit (85), the note would have been replayed, on the condition, as already mentioned, that the system recognized a low pulse of duration less than the minus half of the t ₂ pulses to release the key. In the case of a re-attack or a repetition of close notes, it is preferable to produce the corresponding sound again on a different track, from that of the same sound which has just been produced. Indeed, on the one hand, although the same key is hit, the typing characteristics are likely to be different, and therefore the type of sound emitted slightly distinct, in intensity and timbre, and on the other hand, in a classical string piano, the emission of a note continues well beyond the release of the key, even after application of the damper. Consequently, in order to faithfully render this effect, the repetition of a sound by repeated keystrokes on a key must be able to lead to the production of a sound, on a different channel at each repetition, so as to leave the preceding sound or sounds 'finish normally. Of course, after a certain number of repetitions, the ear no longer succeeds in discriminating the contribution of the oldest repeated attacks, and it is possible to reuse without difficulty the emission channels of these oldest sounds. . A maximum of 2 or 3 ways is enough to achieve 23

a satisfactory "bond" between several repeated notes.

In all cases, it is imperative to let all the sounds produced go out in a damped manner, so as to avoid the known phenomenon of filter slamming, typical of the sudden stop of a sound, causing the emission of a damped sinusoid. To avoid this phenomenon, it is therefore necessary to smooth the damping and stopping of each sound product before complete extinction.

FIG. 10 diagrams the functional blocks of a digital piano provided with the device for reading and exploiting the characteristics of keystrokes according to the invention.

The opto-digital sensor 101 outputs a signal which is interpreted in a module 102 for keystroke detection. In the event of detection of activation of the key associated with the sensor 101, the computer module 103 performs an analysis and a calculation of the striking characteristics, namely of the dynamic "dyn" (representative of the striking speed), and the status of the "spoils" and "atten" signals.

The processing performed by the computer module 103 provides, on the one hand, addressing information for a selector module 104 for reading a memory 105 for storing attack sounds, A ^, A _{2 /} A ₃ , A ₄ to provide the attack sound A _χ corresponding to the keystroke characteristic detected, and on the other hand an envelope calculation 106 determining the intensity, the weakening and the duration of the sound emitted.

The attack sound A- ^ is thus followed by a key hold sound Mx, whose waveform Mx is obtained by reading a memory 105 of sampled hold sounds, and whose envelope (duration , weakening, extinction) is provided by an envelope calculation module 106. 24

The holding sound Mx is advantageously chosen selectively from among several sounds associated with the key struck, so as to correspond to the attack sound Ax. The purpose of this is to simulate the greater richness in harmonics of the sound rendered by a nervous attack in comparison with a softer attack.

Advantageously, the emission of the holding sound Mx undergoes electronic damping, in the absence of any attention controlled by the signal "atten", then the signal "spoils". This electronic damping corresponds to the natural damping of the oscillations of the resonant string.

The emission of the sound is finally carried out through a module 107 for converting the sampled digital signal representative of the attack and hold sounds into an analog audio signal, followed by a circuit 108 attenuator and / or filtering controlled by the module 106 envelope calculation, before possible attack of mixers then output transducers. FIG. 11 represents an electronic block diagram of an embodiment of an optonumeric module mounted at the output of the optical reading sensor of the invention.

This module consists of two sub-modules 111, 112.

The module 111 comprises the sensor 113, the source 114 of which sends a light beam onto the phototransistor 115, selectively closed by the passage of the moving indicator 116. The collector of the phototransistor 115 drives a CMOS integrated circuit 117 for signal processing, in order to get the "code" signal.

Advantageously, the phototransistor 115 is a TR OPB 860 NSI, and the CMOS circuit a CD 4049 MOTOROLA. 25

The configuration of the sub-module 112 shown in FIG. 11 is only a schematic illustrative example of a circuit capable of calculating the signals "atten", "spoils" and "dyn" from the signal "code". Those skilled in the art will be able to produce variants more or less close to this sub-module 112, without departing from the protective field of the present invention.

It will also be noted that it would possibly be possible to provide a version of this sub-module 112 which is common to several keys, and for example mounted in the cards 131 of the embodiment of the keyboard management assembly in FIG. 13 (see below).

The illustrative sub-module 112 of the figure it receives as input the "code" signal coming from the CMOS circuit 117, which comes to attack on the one hand a 12 bit counter 118, and on the other hand, two monostable assemblies 119, 120 each generating a pulse, either on the falling edge of the "code" signal, or on the rising edge of said "code" signal.

The counter 118 is activated by a clock 121 at 300 kHz.

The monostable stages 119, 120 supply short pulses at the output in response to the change of state of the "code" signal, in order to come to reset, adequately, the counter 118, as well as a comparator 122.

The output of the counter 118 is stored in the circuit 123 on command of the pulses generated by the monostable assembly 120 through the door 124.

In order to memorize only the smallest pulse of a sequence of pulses (attack or release) of the "code" signal, gate 124 is blocked by comparator 125, when the current value pulse is greater than the pulse value stored in 123. The current value stored in 123 therefore corresponds to the reference duration selected for the current sequence, and therefore to the "dyn" signal.

The value of "dyn" is also continuously compared with the current pulse value supplied by the signal "code", in comparator 122. The function of this comparator 122 is to produce changes in the state of the "spoiling" signal when l The current pulse of the "code" signal is at least twice the value of the "dyn" signal.

Finally, a flip-flop 126, which receives as input, on the one hand, the signal value "code", and on the other hand the value of the signal "spoils", supplies as output the value of the signal "atten". Figure 12 shows schematically the main components of an electronic piano with digital synthesis of sounds equipped with devices for reading and exploiting the keystroke characteristics of the invention. The 88 keys of the keyboard 150 each provide a signal concentrated in a keyboard management block 151 detailed in FIG. 13. The block 51 is optionally also supplied with information from the harmonic pedal (s) 155. The block 151 supplies a interface 152 with the values of the "code", "dyn", "atten" and "spoils" signals of the activated keys. This interface 152 is interrogated by the central unit 153, which constitutes the brain of the assembly, in association with the user memory 154. The central unit 153 comprises 24 counters for addressing the memory for storing the sampled sounds of attack and sustain 156, corresponding to the 24 output channels of the piano v (the number of channels is not a limiting characteristic of the invention). 27

Advantageously, this memory is a quick access memory, of the ROM, RAM or EPROM type, said memory 156 possibly being rechargeable and / or reprogrammable from a hard disk for storage and / or a memory of CDROM type. 157.

When the information stored in the CDROM 157 are samples stored in compressed form, a decompression interface 158 is responsible for reconstructing them when the memory 156 is loaded.

Where appropriate, when the memory 156 is a dynamic memory, a refresh module 159 can be associated with it.

The memory is sequenced by a clock 160. The output values of the sound memory

156 are stored asynchronously in a buffer memory module 161, responsible for resynchronizing the emission of sounds, under control of the clock 160. The module 161 finally attacks a set 162 of output cards, the number of which corresponds to the number voices that can be played simultaneously. In the embodiment shown, 24 cards, corresponding to 24 different simultaneous sounds, have been provided.

These cards have the function of converting the sampled and resynchronized signals coming from the memory 156, in the form of audio frequency signals.

More precisely, each of the cards of the game 162 receives on the one hand the sampled signal corresponding to the waveform of the attack and sustain sound selected in response to the striking characteristics of the corresponding key, and on the other hand a envelope information, coming from an envelope calculation module 163. This envelope information corresponds to the intensity, the duration, and the type of sound attenuation, as a function of the striking characteristics provided by the interface 152.

The resulting signal, defined in its waveform (composition in harmonics), and in its envelope (intensity, attenuation, duration) is converted into an audible frequency, and then crosses a mixer circuit 164 before attacking the output transducers ( amplifier and speakers for example).

If necessary, the digital piano can also be supplied with external, sequencing or other information, supplied from an input interface 165, 166.

FIG. 13 shows diagrammatically an advantageous embodiment of the assembly for managing the keyboard 151 of FIG. 12.

In this embodiment, the keys are grouped together in sets of eight keys 130, each set being pretreated in a common card 131. This common card ensures successive and cyclic interrogation of each of the eight associated keys, in order to restore them successively on the bus common 132.

The transmission of all the “code”, “dyn”, “atten” and “spoiler” signals, for each key, on the bus 132, is managed by the sequencing circuit 1330. One of the sequencing modes can for example, consisting in selecting a key among eight, then among eleven or twelve (that is to say finally among 88 or 96), so as to each successively deliver the necessary information.

In the case where the signal "dyn" is expressed on 12 bits, the bus 132 has a width of 16 bits, so that it can also carry the monofilament signals "code", "spoils" and "atten". The sequencer circuit 133, controlled by the scan clock 134, has the function of detecting and selecting the activated keys whose typing characteristics exhibit a variation from one scan to the other.

In the embodiment shown, the sequencer circuit supplies a dynamic memory 135 of limited capacity (24 voices). We can consider that the maximum number of 24 simultaneous channels allows an excellent reproduction fidelity, insofar as

10 the ear loses its faculties of discrimination during the simultaneous emission of a plurality of sounds.

In case of saturation of the memory 135, the sequencer 133 ensures the expulsion of one of the memorized keys, according to a given criterion. We can consider

15 as a non-exhaustive expulsion criterion, the choice of the oldest note played, or the choice of the key whose current note is the weakest in intensity or even the choice of the highest note. This last criterion is explained by the fact that the scores

20 trebles have a shorter resonance than the bass notes.

The memory 135 is then interrogated by the central processing unit 153, as described with reference to FIG. 12.

The problems mentioned above of the known devices are thus solved by virtue of the invention, which can be applied to a large number of devices provided that they include a keyboard. As the witness is on the sidelines itself, his

30 movement faithfully reveals the touch thereof, regardless of the parasitic parameters introduced downstream (games for example), and the setting, and the same hit will always give the same reading, and consequently, the same sound memorized in the memory of the

- ^• - _ digital piano in the event that the invention is 30

applied to such an instrument. Also, the presence of a plurality of marks along the witness makes it possible to study the evolution of the speed of the strike, and not only this speed near the impact of a hammer on a rope; we therefore have an image of the acceleration of the key, and we can, using a bar code as a witness, identify fixed variations in speed, and also record extremely different speeds within a determined range of speeds (for example in a report 1000), which allows a fine analysis of the user's touch. Thus, the movement of the key on the go measures an acceleration by comparison of several speeds, and the return of the key measures the exact moment of extinction of the note on the one hand and the repetition threshold on the other hand (degree of key depression from which the note can be replayed). More precisely, the object of the analysis of the signals provided by the witness is the study of the cyclic relationship of these; these signals, called "squares",. are read on the barcode consisting of brands with a duty cycle of 1; when a relevant event must be taken into account, this ratio changes and becomes a basis for counting to obtain different effects and settings: - signal to activate the note ("spoils") earlier or later than normal,

- the same for the extinction allowing the regulation of the start of the dampers in the case of a piano sound for example, - attenuation (pre-extinction) simulating the resonance of the string at the start of the dampers, or any other effect,

- elimination of parasitic events such as trembling of the user's fingers. 31

Finally, the presence of a single sensor with a single beam per key is a considerable saving factor, taking into account the number of keys of certain keyboards, as we have seen more than eighty for a simple piano).

Claims

.

32

1) Optical reading device, in particular for reading the movement characteristics of a key hit on a keyboard, of the type of piano keyboards or the like, characterized in that it is provided with:

- A displacement indicator (30) mounted integral with the key (31), said indicator (30) being provided with a plurality of marks (21, 22) staggered in the direction (E, L) of displacement of the button, and

- A sensor (33; 113) for moving said indicator, comprising means for detecting the passage of said marks when the indicator moves.

2) Device according to claim 1, characterized in that said indicator (30) consists of a transparent support carrying a set of opaque bars (21, 22) staggered in the direction of movement of the key (E, L), said indicator (30) moving between a light source (32; 114) and an optical sensor (33; 115) for displacement of the indicator, so that the passage of said opaque bars (21, 22) in front of the light source ensures interrupting and restoring the light beam received by said optical sensor (33; 115). 3) Device according to claim 2, characterized in that said set of opaque bars (21, 22) is arranged on said support of the indicator (30) of key movement so as to reveal at least three distinct zones s - a first transparent zone (A) corresponding to the rest position of said button; a second zone (B) comprising a plurality of substantially parallel opaque bars, spaced apart in the direction of movement of the key, said zone corresponding substantially to the central part of the key movement;

- a third opaque zone (C) corresponding to the pressed position of said key.

4) Device according to claim 3, characterized in that said second zone (B) comprises from two to ten opaque bars (21) identical, and regularly spaced? and preferably three to four bars (21).

5) Device according to any one of claims 3 or 4, characterized in that the width of each opaque bar (21) is substantially identical to the interval separating two adjacent opaque bars (21), and is chosen so as to correspond the travel of movement of a key for a duration ranging from 100 microseconds to approximately 200 milliseconds.

6) Device according to claim 1, characterized in that said optical sensor (33; 113) is a logic sensor providing at output a crenellated signal, capable of taking two alternating states:

7) Device according to claim 1, characterized in that said key is associated with mechanical resistance members adjustable to impact and depression, and / or to return members of the key in the rest position.

8) Device according to any one of claims 1 to 7, characterized in that it comprises additional means (34) for controlling an additional specific signal by depressing the key. 9) Device according to claim 8, in particular for producing an electronic piano with digital synthesis of sounds, characterized in that said additional means correspond to a vibrato signal control. 10) Device according to claim 8, characterized in that said additional means consist of a second displacement sensor (34) offset relative to said indicator displacement sensor and / or an additional area of said displacement indicator bearing additional specific marks.

11) Device for analyzing and exploiting the movement information provided by an optical reading device according to any one of claims 1 to 10, characterized in that it comprises means capable of determining the direction of movement, the reversals during the race, the speed and / or the acceleration of movement of said hit key. 12) Device for analyzing and exploiting the displacement information provided by an optical reading device according to any one of claims 1 to 10, in the form of a crenellated signal, characterized in that it comprises: counting means (118) of the duration of each high and / or low pulse of the crenellated signal supplied by said optical sensor;

means of exploiting said calculated pulse durations. 13) Device according to claim 12, characterized in that said means for exploiting the stored pulses comprise:

- means for detecting the attack on said hit; means for determining the attack characteristics of said key;

- means for detecting the release of said key.

14) Device according to claim 13, wherein the output signal of the optical pickup sensors consists of a succession of high and low pulses (11), characterized in that said means for detecting the attack of the key are made up:

- means for memorizing (123) the duration of the high and / or low pulses;

- means for recognizing (122) the end of the forced hitting stroke of said key when the ratio of the comparison of the duration of the current pulse with the duration of the previous pulse, and / or a pulse duration of reference, exceeds a predetermined threshold.

15) Device according to claim 13, in which the output signal from the optical reading sensor consists of a succession of high and low pulses, characterized in that said means for detecting the release of the key comprise:

- means (spoils) for recognizing and memorizing an initial state of effective depressing of the key;

- memory means (123) for the duration of each of the high and / or low pulses;

- means for recognizing (122) the limit switch free to release the key when the ratio of the comparison of the duration of 1 • current pulse with the duration of the previous pulse, and / or a pulse duration of reference, exceeds a predetermined threshold.

16) Device according to any one of claims 14 or 15, characterized in that said means for determining the attack characteristics carry out a selection and / or equalization operation to determine a reference duration between said recorded pulse durations.

17) Device according to any one of claims 5 to 16, characterized in that said reference duration is the smallest of the durations noted.

18) Device according to any one of claims 14 to 16, characterized in that said ° reference duration is the duration of the last pulse detected.

19) Device for analyzing and exploiting the movement information provided by an optical reading sensor for a keypad according to any one of claims 1 to 10, in particular for producing an electronic piano with digital synthesis of sounds, characterized in that it comprises:

- means for detecting (102) the keys struck; 0 - means (104) for producing an attack sound as a function of the attack characteristics of the key;

- Means (105) for producing a holding sound extending said attack sound; 5 - means (108) for attenuation and / or over-attenuation of said holding sound when the key is released.

20) Device according to claim 19, characterized in that said means (102) for detecting 0 hit keys comprise:

- calculation means (112), for each key, typing characteristics;

- means (133) for cyclic scanning of all the keys, with identification of the keys, 5 of which striking characteristics have varied from the previous scanning cycle; means (135) for memorizing the typing characteristics of said identified activated keys. 21) Device according to claim 20, characterized in that said means (135) for memorizing the striking characteristics of the activated keys only have a limited capacity for memorizing, and ensure the expulsion of one of the memorized keys.

22) Device according to claim 19, characterized in that said key striking characteristics include:

- information (dyn) of striking dynamics, representative of a striking intensity, and obtained as a function of the duration of the attack and / or release pulse selected;

- information (spoils) of validation of the strike, which passes to the validated state during the recognition of the end of the attack stroke of the key, until the recognition of the end of the stroke free to release said key;

- attenuation information (atten) which is activated when the end of the forced attack stroke of the key is recognized, until the start of the stroke is free to release the key.

23) Device according to claim 19, characterized in that said means for producing an attack sound consist of a memory (105) for storing the different sampled attack sounds corresponding to each key, said memory being addressed by means for selecting (104) the attack sound as a function of the key hit on the one hand, and attack characteristics of said key on the other hand.

24) Device according to claim 23, characterized in that, to each of said keys are associated with at least two distinct attack sounds, each of said attack sounds being selectively associated with a different range in the range of value representative of the characteristics d attack of said key calculated by said means for determining attack characteristics. 25) Device according to claim 19, characterized in that said means (105) for producing a holding sound consist of a memory for storing the different sampled holding sounds corresponding to each key, said memory being addressed by means selection of the holding sound as a function of the key hit and / or of the attack sound selected for said key.

26) Device according to any one of claims 23 and 25, characterized in that said memory (104, 105) for storing sampled sounds of attack and / or maintenance is a fast access memory, of ROM, RAM type or EPROM, said memory possibly being rechargeable and / or reprogrammable, from a hard disk for memorizing and / or a memory of CDROM type.

27) Device according to claim 19, characterized in that said means for attenuation and / or over-attenuation of said holding sound are constituted by a module (108) for receiving the typing characteristics of the keys, receiving input, .for each key activated, dynamic information (dyn), attenuation information (atten) and key press / rest validation information (spoiler), and outputting waveform envelope information representative of the volume, duration and attenuation of said waveform.

28) Device according to any one of claims 23 to 27, characterized in that it comprises means for emitting sounds, consisting of a polytimbre synthesizer (161, 162) receiving as input on the one hand forms d sampled wave of said attack and / or sustain sounds from said memory (105) of sampled sounds, and on the other hand envelope information of said waveform, from said module (108) envelope calculation.

29) Device according to claim 21, characterized in that the criterion for the choice of said expelled key belongs to the group of criteria comprising the choice of the oldest key played, the choice of the key whose current note is the weakest in intensity , and the choice of the highest note.