FR2620255A1 - OPTICAL POLLING DEVICE, IN PARTICULAR FOR THE STRIKE OF A BUTTON ON A KEYBOARD, OPERATING DEVICE OF THE SAME, AND DIGITAL PIANO EQUIPPED WITH SUCH DEVICES - Google Patents

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

Recording device is used to relax the user by pressing a key on a keyboard. disrmosi; f exploitation of said optical survey, e digital piano ecruiné such disrssitifse
The field of the invention is that devices for accurately identify the characteristics of striking a key on a keyboard, including a piano keyboard. The realization of such a statement is particularly useful for the synthetic reconstruction of the sounds of a piano with strings by means of a digital piano. It also makes available to the user or artist a range of several "keystrokes" distinct from the keys, producing different effects.

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

 However, some of the constituents of the invention are also immediately transposable in neighboring fields, obviously to those skilled in the art. By way of example, mention may be made of the production of keypads for the "orchestration" of lighting effects, of water jet games. video synthesis means, etc.

 Electronic keyboards equipped with devices for detecting keystrokes are already known.

 Apart from simple striking detectors based on on-off microswitches or the like, there is notably known a device for detecting the striking force exerted on a key as illustrated in FIG. 1. To know the force of striking exerted 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 inconvenients of operation, but also very important shortcomings as to the accuracy and quality of the survey performed.

 In the order of the mechanical disadvantages, it is possible to note the difficulty of adjusting the flexible flexible blade 12 with respect to the fixed contact 12, 13, the risks of oxidation or coaling of the points of contact between the blade 10 and the contacts 12, 13, and in general all the risks of maladjustment, deformation and wear related to the intense use of a fragile mechanical device.

 More importantly, the survey performed allows only a very basic interpretation of the typing characteristic of the keys. Indeed. only one parameter is raised, namely the speed of movement of the key between two predetermined points. However, to find the touch of the piano, it is especially necessary to allow the artist to choke and reset a note, possibly repetitively, to different driving positions according to the acceleration of the key. This known device then becomes inoperative.

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

 More specifically, an essential object of the invention is to provide a device for recording the striking characteristics of the keys of a keyboard that allows the faithful reconstruction of all forms of touch practiced on piano å strings. However, the sophistication of the reading device allowing such fidelity of reproduction must also be able to authorize to widen the application of the invention, for example for the creation of new touch characteristics and / or the production and creation of others. types of sounds.

 An additional objective of the invention is to provide a sound recording and production device in which no noticeable delay must be felt between the depression of a key and the appearance of the sound, regardless of the keystroke.

 Another complementary object of the invention is to simulate the operation of the hammer in string pianos, providing a device that allows a note to be triggered on acceleration effect produced on a moving key. while it has not yet reached the end of its previous race.

 Another object of the invention is to provide a device that simulates the function of the damper in stringed pianos, by allowing a depressed note to be released at two-thirds or 9-stroke without choking. The damper threshold, if any, must be adjustable.

 A complementary objective of the invention is to provide a survey device which is of low cost, and high reliability and wear resistance.

 The invention also aims to provide a device for synthesizing sounds that takes into account the characteristics of the striking of each key for the production of a corresponding sound according to an intensity, a waveform, and a wealth of 'harmony given. Advantageously, the invention must also be able to be the subject of a breprogramming to modify the sounds associated with each type of keystroke.

 Another object of the invention is to provide a complete chain of production 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 notes held, notes quilted, stifled, repeated, trills and tremolos obtained on stringed pianos, with reconstruction of the attack of each note, its holding, and its extinction in the most faithful way possible.

These objectives, as well as others which will appear later, are achieved by means of an optical recording device, in particular for the recording of the characteristics of movement of a key struck on a keyboard, of the type of piano keyboards. or the like,
characterized in that it is constituted
- A displacement indicator mounted integral with the key, said indicator being provided with a plurality of marks staggered in the direction of movement of the key, and
a sensor for moving said witness, comprising means for detecting the passage of said marks during the movement of the witness.

 Advantageously, said witness consists of a transparent support carrying an opaque set of bars staggered according to the direction of movement of the key, said witness scrolling between a light source and an optical sensor for moving the witness when the key is struck. the associated key, so that the passage of said opaque bars in front of the light source ensures the interruption and recovery of the light beam received by said optical sensor.

According to another characteristic of the invention. said optical sensor is a logic sensor outputting a crenellated signal capable of taking two alternating states
- A first state when the captured light beam has a brightness greater than a predetermined threshold;
a second state when said captured light beam has a brightness lower than said predetermined threshold.

 The objectives of the invention are also achieved by means of a device for analyzing and using the displacement information provided by the optical survey device described above, characterized in that it comprises means capable of determine the direction of movement, the creep during the stroke, the speed and the acceleration of movement of said struck key.

In a preferred embodiment of the invention. said device for analyzing and exploiting the displacement information provided by said optical survey device in the form of a two-state warped signal comprises
means for detecting the attack of the key;
means for determining the attack characteristics of said key;
means for detecting the release of the key;
Advantageously, when the output signal of the optical pickup sensor consists of a succession of high and low pulses, said means for detecting the attack of the key are constituted
means for storing the duration of each of the high and / or low pulses;
means for recognizing the end of stroke of forced striking of said key when the ratio of the comparison of the duration of the current pulse with the duration of the preceding pulse and / or a reference pulse duration exceeding one predetermined threshold.

 Advantageously, said means for determining the striking characteristics of each key consist in performing 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 measured pulse durations or the last pulse duration immediately preceding the forced-stroke end-of-stroke recognition. 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 struck striking characteristic. Advantageously, can provide at least two different attack sounds by keys, or even more, depending on the membership of the pulse duration and / or the key strike rate has 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 depression of the key;
means for storing the duration of each high and low pulse of the crenel output signal of the optical pickup sensor;
means for recognizing the end of travel free to release the key when the ratio of the comparison of the duration of the current pulse with the duration of the preceding pulse and / or a reference pulse duration exceeds one preset threshold.

 Advantageously, and so as to simulate the behavior of a stringed piano. the touch release is accompanied by a forced attenuation when detecting the release of the key (approach of the damper against the resonant stringj, å which is added a "strengthened" attenuation during the recognition of the end the free stroke to release the key (complete application of the damper on the resonant string to cause the total extinction of the sound).

Particularly in the application of the invention to the production of a digital sound synthesis electronic piano, the device for analyzing and operating the displacement information provided by the optical pickup sensor of the keystroke characteristics is characterized in that it comprises
- Key detection means struck. preferably comprising calculation means for each key of the striking characteristics, means for cyclic scanning of all the keys with registration and selection of the keys activated from the previous scan, and means for memorizing the striking characteristics of said activated keys; ;
means for producing a driving sound comprising a memory for storing at least two sampled driving sounds for each key, said memory being addressed by means of selection of the attack sound according to the key hit and depending on the attack characteristics of said key;
means for producing a sustain sound prolonging said attack sound, constituted by a memory for storing at least one sampled sustaining sound for each key, addressed as a function of each key struck and, where appropriate, according to attack sound when several sustain sounds are provided by key;
means for attenuating and / or over attenuating said sustaining sound as a function of intensity waveform envelope information.

in duration and in attenuation from an envelope compilation module, depending on the typing characteristics of each activated key.

In a preferred embodiment, said means for memorizing the keying characteristics of the activated keys comprise only a limited memory capacity. and ensure the expulsion of one of the stored keys; the criterion of the choice of 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 rating is the lowest in intensity, and the choice of the highest note.
Advantageously, said digital sound synthesis electronic piano device comprises a sound emission unit consisting of a polytimbre synthesizer receiving as input on the one hand the sampled waveforms of the attack and sustaining sounds. from said sampled sound memory, and on the other hand envelope information from said key typing compilation module.

Other features and advantages of the invention will appear on reading the following description of preferred embodiments of the invention, given in a non-limiting manner, and the accompanying drawings in which:
FIG. 1 schematizes the prior device discussed in the preamble;
FIG. 2 represents a preferred embodiment of the optical opaque bar indicator of the optical pickup device according to the invention;
FIG. 3 schematizes a preferred type of mounting of the indicator of FIG. 2 on a keyboard key;
FIG. 4 is a diagram illustrating, in the general case, the form of the signals representative of the keystroke characteristics, as recorded and calculated from said optical pick-up sensor of the invention;
FIG. 5 is a diagram of the type of FIG. 4, illustrating the speed of the response times of the operating means of the signals coming from the optical sensor according to the invention;
FIG. 6 is a diagram of the type of FIG. 4 illustrating the simulation of the control of the damper in an electronic piano equipped with the device of the invention; ;
FIG. 7 is a diagram, of the type due to FIG. 4, illustrating the behavior of the devices for recording and exploiting the keystroke characteristics during a key attack repetition;
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 case of a "note note" type key attack; ,
FIG. 9 is a representative schematic diagram of the output signal of the optical reflex sensor according to the invention, illustrating the range of accuracy and sensitivity of said sensor;
FIG. 10 is a block diagram of an embodiment of a digital piano provided with devices for reading and exploiting the key-typing characteristics of the invention;
FIG. 11 is an electronic block diagram of an embodiment of an opto-digital module mounted at the output of the optical pick-up sensor according to the invention for obtaining useful signals representative of the typing characteristics of the keys;
FIG. 12 is a simplified diagram illustrating an embodiment of the connections between the various modules constituting a digital piano provided with a device according to the invention;
FIG. 13 is an illustrative diagram of the management means of an 88-key keyboard, each key being provided with an optical recording device of the striking characteristics according to the invention;
The design of the device for optical recording of the striking characteristics of a keypad according to the invention is derived from the in-depth analysis of the touch and the rendering of sounds in a classical stringed piano.
Two types of considerations are to be considered in a detailed touch analysis:
- the mechanical behavior of the chain of elements connecting each key to the corresponding set of strings, in a classical stringed piano;
- the characteristics of the sound spectrum made by the strings according to the touch.

 Among the essential elements of the mechanism of transmission of the touch to the strings, it is necessary to note the important role played on the one hand by the hammer of striking of the strings, and on the other hand by the felt of choking of the resonance of struck strings. The hammer has the function of causing the keystrokes only when a certain threshold of depression and / or a certain speed of striking a key are crossed. In addition, the intensity of the note rendered depends closely on the striking force of the hammer, itself linked to the speed of depression of the associated key. In addition, the so-called "double-escapement" system in advanced grand pianos allows a fast repetition of notes, even if the key has not been released completely. After the keystroke, each string hits first. natural damping of the libration, which is then greatly attenuated during the application of the damper on the ropes. The action and damping effect of the damper can be controlled between temporarily holding the key in the fully depressed state and then by releasing the key.

 Note also the role of harmonic pedals.

a major improvement of which is the subject of the patent application 86 08177 filed by Denis de la ROCHEFORDIERE, also co-inventor of this patent.

 Regarding the spectrum of the sound of strings according to the touch, it should be known that, in a classical string piano, the sound obtained is richer in harmonic when a touch "strong" and "fortissimo", that at the touch of a "piano", or "pianissimo" This effect is due to the phenomenon of sympathetic resonance of the whole string plane, which increases with the hammer's speed of striking, and the greater compression of the hammer. felt of the hammer.

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

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

as well as the attenuation and extinction characteristics of the sound as a function of the release of the keys.

 These objectives are achieved with the aid of an optical pickup sensor of the type shown in FIGS. 1 and 2.

 The present description of a detailed embodiment of the invention is specifically related to the application of optical reading devices and exploitation of the striking characteristics of a key to the production 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 uses ensisageables keyboards, as mentioned in the preamble.

 In the embodiment of FIG. 3, the displacement indicator 30 is mounted at the end of the hinged key 31, so as to be interposed between an optical source 32 and an optical pickup sensor 33.

 Advantageously, the indicator is mounted at the end of the key 31 opposite to 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 struck, the warning light 30 moves in the direction of "depressing" E in front of the sensor 33. During the letting go, the direction of movement L of the telltale 30 is reversed.

 If necessary, a second sensor 34 may be provided for the management of an effect. over-pressing the key. This over-burst effect may optionally be desired to obtain a tremolo, vibrato, or other. An equivalent means consists in providing a fourth zone 9 opaque bars on the control 30 as represented in FIG.

 Advantageously, the control 30 of FIG. 2 is formed of a transparent mylar plate on which the opaque bars 21 have been affixed.

as well as an extended opaque zone 22. These marks are distributed over a reading range 1, corresponding to the approximate travel distance of the indicator 30 during a complete hit of a key. The range I can be broken down into three zones successively crossed during the displacement of the control in direction E or L
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 in the direction of movement E, L of the key and corresponding to the central portion of the stroke of movement of the key;
a third opaque zone 22 corresponding to the depressed position of said key.

 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. 1), a crenellated "code" signal referenced 23 in FIG. 2. The passage of light through a transparent zone corresponds to the zero (low) state of the crenellated signal, and the interruption of the light beam corresponds to the state I (high).

 The zone B of the control 30 carrying the parallel opaque bars 21 may advantageously comprise, but not necessarily, 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 pickup device according to the invention to faithfully respond to key recesses before complete release. re-accelerations of keys being pressed, and any type of repetitive strike.

 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 operating circuits of the signals supplied by the sensor 33, it will be possible to envisage using bars of different widths (linearization of the responses. ...).

 The multiplication of the number of opaque bars 21 also has the advantage of allowing a plurality of values to be obtained during a movement of the key. This plurality of values makes it possible, on the one hand, to calculate an acceleration value of the key and, on the other hand, to detect possible errors in readings due, for example, to the presence of dust that inadvertently closes the light beam received by the sensor 33 .

 Figure 9 illustrates the range of accuracy and sensitivity of the sensor, which has been chosen to be able to detect pulses of durations ranging from 100 microseconds to 200 milliseconds. These values were recorded and optimized experimentally on prototype. The corresponding indicator has bars of about 0.3 mm. In a preferred embodiment of the invention, this scale makes it possible to define an accuracy of 4096 steps on 12-bit words. the ratio of the minimum and maximum speeds after treatment being at least equal to 1/1000. The sensor according to the invention therefore allows considerable precision, and allows a touch analysis and sound reproduction extremely fine and faithful, incommensurate with existing devices.

 In an advantageous embodiment, each key is associated with members 100 of adjustable mechanical resistance to striking and depression, and / or å 100 members of the key rest in the rest position to simulate the conditions of to touch on stringed piano.

 Figure 4 is an illustrative diagram. in the general case. the shape of the signals representative of the keystroke characteristics. as read and calculated from the optical survey sensor of Figure 2.

This diagram consists of 4 distinct signals
a "code" signal obtained on I bit at the output of the optical reading sensor. possibly after preliminary treatment described later with regard to FIG. 11;
a dynamic "dyn" signal consisting of 12-bit words representative of the duration of each "low" and "high" pulse of the "code" signal. Of course, the length of the word mentioned does not constitute a limiting feature of the invention.

a signal "gate", on I bit, representative of a validation information of the keystroke, which goes to the validated state when the recognition of the end of the stroke of forced striking of the key, until the recognition end of stroke free to release said key;
an "attentive" signal, on 1 bit, representative of attenuation information that is activated during the recognition of the end-of-stroke forcing the key, until the detection of the beginning of a free race to release said key.

 As already mentioned with reference to FIG. 2, two pulse weights can be distinguished in the crenellated signal "code", namely low level pulses 41, 43a, 43b, 43c, 45a, 45b, 45c, 47, and high level pulses 4, a.4, b, 42c, 44, 46a, 46b, 46c.

In the sequence shown, the key successively undergoes four distinct phases
a phase 1 of attack of 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 43a, 43b, 43c respectively corresponding to the passage of opaque bars 21 and intervals between opaque bars.

a phase 2 of prolonged pressing of the key, in which the "code" signal is in the "high" continuous state 44, because of the complete blocking of the light beam by the extended bar 22 of the control 30;
a phase 3 to release the key, in which the succession of low pulses 45a, 45b, 45c and high 46a, 46b, 46c corresponds to the passage of the opaque bars 21 in front of the sensor 32, in the opposite direction to that of the phase A of attack;
a phase 4 corresponding to the stabilization of the key in the rest position. maintaining 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 completed version. the duration calculations relate to the zero level pulses 43a, 43b, 43c, 45a, 45b, 45c and 47 as well as to the prolonged driving pulse 44. Of course, it is also possible to selectively raise the duration of the high pulses or the duration of all the high and low pulses.

 The "gate" signal 60 goes from the zero (low) state to the one (up) state when the key forcing key is recognized. This is advantageously achieved when it is found that the high level pulse immediately following a low level pulse 43a, 43b, 43c extends over a time t greater than twice the duration tl of said low level pulse. In the diagram of FIG. 4, this case intervenes only after the pulse 43c, and is found after the duration t 2 = 2.tlc immediately following the pulse 43c of low level and duration t1c.

 Symmetrically, the inverse passage of the "gate" signal 60 from the high level to the low level is controlled when the sensor detects a low pulse of duration t4 at least equal to twice the duration of the measured impulse immediately preceding. In the diagram of FIG. 4, this condition is realized only when the "code" signal 47 is detected immediately following the low pulse 45c of duration t3c.

 Of course, the multiplier "2" recommended does not constitute a limiting feature of the invention.

 The function of the "gate" signal 60 is, on the one hand, to recognize the end of the attack zone I of the struck key, in order to determine the attack sound to be produced according to the durations tla.tlb , tlc stored as will be seen below, and secondly to achieve a "strengthened" attenuation of the signal when it was detected the end of the free run to let go of the key. This enhanced attenuation must be able to cause the total extinction of the sound within a range of 2 ms to 500 ms (possibly adjustable value) so as to simulate a natural break.

 The "attentive" signal 70 goes from the low level to the high level in the same conditions as the "gate" signal 60. On the other hand, this signal returns to the zero level when the detection of the touch signal 71 is detected, as will be seen in detail. further.

 FIG. 5 illustrates the speed of the response time of the optical detection device and the exploitation of the keystroke characteristics according to the invention. In this diagram, it is noted that the driving pulses 51 provided by the "code" signal 40 have weak durations, which schematically corresponds to a strong attack which must provide a note of strong intensity, and rich in harmonics. In this case, the "gate" signal 60 passes very quickly to level 1 (52). the duration ta = 2t1 being short. Conversely, in the case of a light strike. the response time would be longer. which corresponds to reality in classical 9-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 loosing frank. This case corresponds to the retention of the damper in a classical stringed piano, by approximately maintaining the key in the depressed state.

 Despite the existence of pulse tA, tB in the crenellated signal "code" 40, the "gate" signal 60 does not return to the zero level. This is due to the fact that at no time does the detector detect a limit-free end-of-travel recognition (t4> = 2t3, see fig.4).

 On the other hand, the signal "atten" 70 undergoes some variations, and returns to the zero state 9 each time a low pulse 62, 64, follows a prolonged high pulse 61, 63 symptomatic of a depression held by the key. Conversely, each passage of the "code" signal 40 at an extended high level 61, 63, 65 following a short low pulse t1, tA, tB, causes a rise in the "atten" signal 70 at the high level.

 The trembling found on the key by the succession of slots of the signal "code" 40 does not, however, cause a repetition of note Ä unl difference of the case of Figure 7. Indeed, as will be seen below, the signal "code 40 of FIG. 6 does not verify the necessary condition, namely that the duration tA tB of the crenelated secondary sequences of the "code" signal 40 is smaller than the duration t1 of the initial attack pulses of the key.

 The signal "code" 40 of Figure 7 is representative of a succession of lachers and reattaching a key, the attack is effected even before the key has returned to its rest position. The note reissue command is performed by passing the "gate" signal 60 from the zero state to the state 1, at 76, 77, ....

The variation of the "gate" signal 60 only occurs when two conditions are realized
the impulse t2 is less than half of the duration of the previous impulses,
- the pulses of the zero level t2, t3, t4 of attacking the keys are followed by a high pulse of duration at least double (confirmation of depression of key).

 In all the cases illustrated in FIGS. 4 to 7, the reference pulse, for each train of quasi identical pulses (driving phase, or lag phase) is the pulse of minimum duration. However. it is also possible to choose a reference pulse duration corresponding to the last stored pulse, or to an equalization calculation performed on all the times t1A, t1B, tlC, etc., stored during a single memory pulse. phase.

 It will also be noted that, in the diagrams shown, the "atten" signal 70 does not automatically anticipate a return to zero of the "gate" signal when it returns to the low level (see FIG. 6). Indeed, the "atten" signal controls the means of simulation of the approach of the damper against the (or) chord (s) resonant (s). that the skilled pianist can control. On the other hand, the signal "gate" commands 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 quilted note.

 In the "code" signal 40, an attack phase 81 is recognized, followed by a phase 82 of letting go, this phase 82 of letting go before the key is depressed for a long time, and thus before the end of the driving stroke. of said key (no prolonged pulse 44 as in FIG. 4).

 However, since the raising of the key is always slower than the depression, since the touch lift is never forced, the first high pulse 82 of the phase 82 to let go has a duration much greater than 2 times. the duration tl of the representative pulse of the attack phase 81.

 As a result, the system correctly performs the forced attack limit switch recognition of the key, and controls the passage of the "gate" signal 60 to the high level (84).

 If the key was re-entered again, before acknowledging the limit switch to freeze (85), the note would have been replayed, provided, as already mentioned, that the system recognized a low pulse of less than less than half of the t2 pulses to drop.

 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 voice of the same sound that comes from between products. Indeed, on the one hand, although the meme touches is fra: pée. the striking characteristics are likely to be different. and therefore the type of sound emitted slightly distinct, in intensity and timbre. On the other hand. in a classical 9-string piano, the emission of a note continues well beyond the touch of the keys, even after the damper has been applied.As a result, to accurately reproduce this effect, the repetition of a sound by striking Repeated on a key must be able to lead to the production of a sound, to each.

repetition on a different voice, so as to let the previous sound (s) end normally. Of course, after a certain number of repetitions.

The ear can no longer discriminate the contribution of the oldest repeated attacks, and it is possible to reuse the transmission channels of these oldest sounds without any inconvenience. A maximum of 2 or 3 channels is sufficient to achieve a satisfactory "weld" between several repeated notes.

 In any case, it is imperative to let all the sounds produced go off in a damped way, so as to avoid the known phenomenon of filter clapping, typical of the sudden stop of a sound, causing the emission of an "attenuated sinus" To avoid this phenomenon, it is necessary to smooth the damping and stopping of each product sound before complete extinction.

 FIG. 10 schematizes the functional blocks of a digital piano equipped with the device for reading and exploiting the key-typing characteristics of the invention.

 The opto-digital sensor 101 outputs a signal that is interpreted in a keypress detection module 102. In the event of an activation detection of the key associated with the sensor 101, the computer module 103 carries out an analysis and a calculation of the striking characteristics, namely of the dynamic "dyn" (representative of the typing speed), and the state of the signals "gate" and "atten".

 The processing carried out by 103 provides on the one hand an addressing information of a selector module 104 for reading a memory 105 for storing attack sounds, A1, A2, A3, A4 to provide the attack sound Ax corresponding to the detected key striking characteristic and secondly, an envelope calculation module 106 determining the intensity, the attenuation and the duration of the emitted sound.

 The attack sound Ax is followed by a key maintaining sound Mx, whose Mx waveform is obtained by reading a memory 105 of sampled sustaining sounds, and whose envelope (duration, attenuation, extinction) is provided by an envelope calculation module 106.

 The sustaining sound Mx is advantageously selected separately from several sounds associated with the struck key. to match the attack eDn Ax This is intended to simulate the greatest harmonic richness of the sound rendered by a nerve attack in comparison to a softer attack.

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

 The sound emission is finally achieved through a sampled digital signal conversion module 07 representative of the audio frequency analog signaling and sustaining sounds, followed by an attenuator and / or filtering circuit controlled by the module 106 for calculating the envelope, before possibly attacking mixers and then output transducers.

 FIG. 11 represents an electronic block diagram of an embodiment of an opto-digital module mounted at the output of the optical survey sensor of the invention.

 This module consists of two submodules 111, 112.

 The module 111 comprises the sensor 113 whose source 114 sends a light beam to the phototransistor 115, selectively closed by the passage of the mobile indicator 116. The collector of the phototransistor 115 drives a signal processing integrated circuit CALOS 117, in order to obtain the signal "code".

 Advantageously, the phototransistor 115 is a TRWOPB 860 IN'SI and the cicuit CMOS a CD 4049 MOTOROLA.

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

 Note also that it would be possible to provide a version of this submodule 112 that is common to several keys, and for example mounted in the cards 131 of the embodiment of the keyboard management assembly of Figure 13 (to see further).

 The illustrative submodule 112 of FIG. 11 receives as input the signal "code" coming from the CMOS circuit 117, which attacks a 12-bit counter 118 on the one hand, and two monostables 119, 120 generating on the other hand each an impulse. either on the falling edge of the signal "code" or on the front of my tan: said signal "code".

The counter 118 is activated by a clock 121 at 300 kHz
Monostabla 119, 120 output short pulses in response to the change of state of the signal "code", to come back to zero, 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 120 9 through the door 124.

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

 The value of "dyn" is also continuously compared to the current pulse value provided by the "code" signal, in the comparator 122. This comparator 122 has the function of producing the state changes of the "gate" signal when the current pulse of the signal "code" is at least twice the value of the signal "dyn".

 Finally, a flip-flop 126, which receives on the one hand, on the one hand, the "code" signal value, and on the other hand the value of the "gate" signal, outputs the value of the "atten" signal.

 Figure 12 schematizes the main components of a digital sound synthesized electronic piano equipped with devices for reading and exploiting the keystroke typing features of the invention.

 The 88 keys of the keyboard 150 each provide a concentrated signal in a keyboard management block 151 detailed in FIG. 13. The block 51 is optionally also powered by a harmonic pedal information (s) 155. The block 151 supplies a interface 152 with the values of the "code", "dyn", "atten" and "gate" 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 addressing counters of the storage memory sampled sounds of attack and holding 156, corresponding to the 24 output channels of the piano (the number of channels is not a limiting feature of the invention).

 Advantageously, this memory is a fast access memory.

of the RONI type. RANI or EPRO! S5, said memory 156 possibly being rechargeable and / or reprogrammable from a storage hard disk and / or a CDROM memory 157.

 When the information stored in the CDROM 157 is a sample stored in compressed form, a decompression interface 158 is responsible for reconstituting it when the memory 156 is loaded.

 If necessary, when the memory 156 is a dynamic memory, a refreshing module 159 may be associated with it.

 The sequencing of the memory is provided 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 transmission of sounds, against clock 160. The module 161 finally attacks a set of cards 162 the number of which corresponds to the number of voices that can be simultaneously played. In the embodiment shown.

24 cards, corresponding to 24 different simultaneous sounds, have been planned.

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

 More specifically, each of the cards of the set 162 receives on the one hand the sampled signal corresponding to the waveform of the attacking and sustaining sound selected in response to the striking characteristics of the corresponding key, and on the other hand a envelope information from a computational module 163.

 This envelope information corresponds to the intensity, the duration.

and the type of sound attenuation, depending on the striking characteristics provided by the interface 152.

 The resulting signal, defined in its waveform (harmonic composition), and in its envelope (intensity, attenuation, duration) is converted into audio frequency, then passes through a mixer circuit 164 before driving the output transducers (amplifier and speakers for example).

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

 FIG. 13 schematizes an advantageous embodiment of the keyboard management assembly 151 of FIG. 12.

 In this embodiment, the keys are grouped into sets of eight keys 130 each set being pre-processed in a common card 131. This common card provides a successive and cyclic interrogation of each of the eight associated keys, to restore them successively on the common bus. 132.

 The transmission of all the "code", "dyn", "atten" and "gate" signals, for each key, on the bus 132, is managed by the sequencer circuit 1330. One of the sequencing modes can for example, to display a 3-bit counter (and thus 23 = 8 states, corresponding to the eight keys) associated with each card 131 successively each of the eight states, simultaneously for all the cards 131. The 11 cards 131 are then successively interrogated , for each state of the counters, by the sequencer module 133, so as to successively deliver the information of the row key selected by the 3-bit counter. on the bus 132.

 In the case where the signal "dyn" is expressed on 12 bits, the bus 132 has a width of 16 bits, so as to also route the single-wire signals "code", "gate" and "atten".

 The sequencer circuit 133, controlled by the scan clock 134, has the function of detecting and selecting the activated keys whose striking characteristics have a variation of a scan on the other.

 In the embodiment shown, the sequencer circuit supplies a dynamic memory 135 of limited capacity (24 voices). It can be considered that the maximum number of 24 simultaneous voices allows an excellent fidelity of reproduction, insofar as the ear loses its faculties of discrimination during the simultaneous emission of a plurality of sounds.

 In the event of saturation of the memory 135, the sequencer 133 ensures the expulsion of one of the stored keys, according to a given criterion. The choice of the oldest note played, or the choice of the key whose current score is the lowest in intensity or the choice of the most acute note, may be considered as expulsion criteria. This last criterion is explained by the fact that the high notes have a resonance of shorter duration than the low notes.

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

Claims (27)

REEDINGS 1) Optical surveying device, particularly for recording the characteristics of movement of a key struck on a key, such as piano keyboards or the like, characterized in that it consists of: - a witness (30) movement mounts on the key (I), said indicator (30) being provided with a plurality of marks (21, 22) staggered in the direction (E, L) of movement of the key. and a sensor (33; 113) for moving said witness, comprising means for detecting the passage of said marks during the movement of the witness.  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) traveling between a light source (32; 114) and an optical sensor (33)  115), so that the passage of said opaque bars (21, 22) in front of the light source ensures the interruption and recovery of 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 disposed on said support of the control (30) of displacement of key so as to show at least three distinct areas  a first transparent zone (A) corresponding to the rest position of said key  - A second zone (B) having a plurality of substantially parallel opaque bars, spaced in the direction of movement of the key. said zone corresponding substantially to the central part of the displacement stroke of the key;  a third opaque zone (C) corresponding to the depressed 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 opaque bars (21) adjacent, and is chosen to match the movement of a key for a duration ranging from 100 microseconds to 200 milliseconds.  6) Device according to claim 1, characterized in that said optical sensor (33; 113) is a logic sensor outputting a crenellated signal, capable of taking two alternating states:  a first state when the captured light beam has a brightness greater than a predetermined threshold;  - A second state when said captured light beam has a brightness below said predetermined threshold.  7) Device according to claim 1, characterized in that said key is associated with members of mechanical resistance adjustable to the striking and depression, and / or has return members of the key in the rest position.  8) Device for analyzing and using the displacement information provided by an optical reading device according to any one of claims I to 7, characterized in that it comprises means capable of determining the direction of movement, the creep during the course of the race, the speed and / or acceleration of movement of said struck key.  9) Device for analyzing and using the displacement information provided by an optical survey device according to any one of claims 1 to 7, in the form of a crenellated signal, characterized in that it comprises  counting means (118) for the duration of each high and low pulse of the crenellated signal supplied by said optical sensor;  means for exploiting said calculated pulse durations.  10) Device according to claim 9, characterized in that said operating means of the stored pulses comprise  means for detecting the attack of said struck key;  means for determining the attack characteristics of said key;  means for detecting the loosening of said key.  11) Device according to claim 10, wherein the output signal of the optical survey sensors consists of a succession of pulses (II) high and low, characterized in that said means for detecting the attack of the key are made up of:  - Storage means (123) of the duration of the high and / or low pulses;  recognition means (122) for 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 preceding pulse, and / or a reference pulse duration , exceeds a predetermined threshold.  12) Apparatus according to claim 10, wherein the output signal of the optical pickup sensor is constituted by a succession of high and low pulses. characterized in that said means for detecting the release of the key comprise  - means (gate) for recognizing and memorizing an initial state of effective depression of the key;  means for storing (123) the duration of each of the high and low pulses;  - recognition means (122) of the end of travel 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 pulse duration reference, exceeds a predetermined threshold.  13) Device according to claim 1 1 or 12, characterized in that said means for determining the driving characteristics perform a selection operation and / or equalization to determine a reference time between said pulse durations noted.  14) Device according to any one of claims li å 13, characterized in that said reference period is the smallest of the durations noted.  15) Device according to any one of claims 1 I to 13, characterized in that said reference period is the duration of the last pulse detected.  16) A device for analyzing and using the displacement information provided by an optical pickup sensor for keypad according to any one of claims 1 to 7, in particular for producing an electronic piano with digital sound synthesis characterized in that it comprises:  detection means (102) for struck keys;  - means (104) for producing a driving sound according to the attack characteristics of the key;  means (105) for producing a sustain sound prolonging said attack sound;  - Means (108) for attenuation and / or over-attenuation of said hold sound during touch-up.  17) Device according to claim 16, characterized in that said means (10 =) for detecting struck keys comprise  calculation means (112) for each key. of: typing characteristics;  means (133) for cyclic scanning of all the keys, with identification of the keys whose striking characteristics have varied with respect to the preceding scanning cycle;  means (135) for storing the striking characteristics of said activated keys identified.  18) Device according to claim 17, characterized in that said means (135) for memorizing the keystroke characteristics of the activated keys comprise only a limited memory capacity, and ensure the expulsion of one of the stored keys.  19) Device according to claim 16, characterized in that said key striking features include:  a typing dynamic information (dyn), representative of a striking intensity, and obtained as a function of the duration of the attack pulse and / or of the selected leash;  - a validation (gate) validation, which goes to the validated state when recognizing the end of the attack stroke of the key, until the recognition of the end of the free race to let go of said key;  attenuation information (attenuation) which is activated during the recognition of the forced attic limit switch of the key, until the detection of the start of the stroke free to release said key.  20) Device according to claim 16, characterized in that said means for producing a driving sound are constituted by a memory (105) for storing the different sampled attack sounds corresponding to each key. said memory being addressed by selection means (104) of the attack sound depending on the struck key on the one hand, and the attack characteristics of said key on the other hand.  21) Device according to claim 20, characterized in that, each of said keys are associated with at least two distinct driving sounds, each of said attack sounds being selectively associated with a different range in the range of value representative of the characteristics of the attacking said key calculated by said means for determining the driving characteristics.  22) Device according to claim 16, characterized in that said means (105) for producing a holding sound are constituted by a storage memory of the different sampled holding sounds corresponding to each key, said memory being addressed by means selecting the sustaining sound according to the struck key and / or the attack sound selected for said key.  23) Device according to any one of claims 20 and characterized in that said memory (104, 105) for storing sampled sounds of attack and / or maintenance is a fast access memory, ROM, RAM or EPROM, said memory being optionally rechargeable and / or reprogrammable, from a hard disk storage andZou a CDROM type memory.  24) Device according to claim 16, characterized in that said means for attenuation and / or over-attenuation of said holding sound consist of a module (108) for receiving the key striking characteristics, receiving as input, for each activated key, a dynamic information (dyn), attenuation (attenuation) information and push-in / key-off validation (gate) information, and outputting waveform envelope information representative of the volume, the duration and the attenuation of said waveform.  25) Device according to claims 20 to 24, characterized in that it comprises means for transmitting sounds, consisting of a polytimbre synthesizer (161, 162) receiving on the one hand on the one hand sampled waveforms of said driving and / or sustaining sounds from said sampled sound memory (105), and envelope information of said waveform. from said envelope calculation module (108).  26) Optical survey 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 over-pressing the key.  27) Device according to claim 26, in particular for the production of a digital piano digital sound synthesis, characterized in that said additional means correspond to a vibrato signal control.  28) Device according to claim 26, characterized in that said additional means consist in providing a second displacement sensor (34) offset with respect to said control displacement sensor and / or an additional area of said displacement indicator carrying additional specific marks. .  29) Device according to claim 18 characterized in that the criterion for choosing 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 lowest in intensity, and the choice of the most acute note.