EP0813732B1 - Motion sensor for a piano key motion analysis system - Google Patents

Abstract

A motion sensor device particularly suitable for use under a piano keyboard in an opto-electronic piano key motion analysis system. The device comprises a body (24, 26) attachable to the piano under the keys thereof, and at least one element (12) that is movable relative to the body (24, 26) and has one end (11) contacting the underside of a piano key. The mutually contacting surfaces of the movable element (12) and the key include a magnetic element (14, 16) and a corresponding magnetic or magnetisable element (14, 16) whose mutual pull is determined in such a way that the end (11) of said movable element (12) remains in contact with the key during normal use.

Description

The subject of the invention is a device forming a displacement and finds its application in particular under the keyboard of a piano in an optoelectronic key movement analysis system of a piano.

To reproduce the sound of a piano, with all its finesse, it it is not enough to know how long the pianist has operated a touch. You also need to know how; that is to say what are the characteristics of the displacement in amplitude and speed. For that, we places under each note of the keyboard a sensor fitted, for example, with a flap which, depending on the position of the key, will modify the characteristics of a beam emitted by a light-emitting diode, in particular reflect it or cut it more or less. The signal recorded by a receiving diode can then be converted to electrical form and processed by computer.

• ils exercent pour maintenir le contact entre l'élément mobile et la touche une force tendant à relever la touche suffisamment sensible pour gêner un pianiste confirmé;
• ils ont une mauvaise fiabilité;
• leurs caractéristiques évoluent dans le temps.

To follow the movement of the keys of the piano, it is already known to use sensors of the type comprising a body intended to be fixed to the piano, under the keys and at least one element movable relative to the body, having one end in contact with the underside of a piano key. However, these devices using in particular a spring to maintain contact between the movable element and the key have the following drawbacks:

• they exert to maintain contact between the movable element and the fingerboard a force tending to raise the fingerboard sufficiently sensitive to disturb a confirmed pianist;
• they have poor reliability;
• their characteristics change over time.

A key movement analysis system piano is described in document US-A-5,062,342.

The invention overcomes these various problems by providing according to claim 1 a device forming a sensor for displacement used in particular in an optoelectronic analysis system of the movement of the keys of a piano characterized in that to ensure the followed by the movement of lowering / raising the key, it includes, fixed under the underside of each button, a magnetic element or magnetizable which cooperates with a magnetic or magnetizable element complementary linked to a mechanical element of analysis the modification of a system characteristic, such as a movable flap when uses an optoelectronic system, said magnetic elements or magnetisable cooperants remaining in permanent mutual contact during the normal operation of the device.

According to a preferred embodiment the new electronic device analysis and tracking of key movement uses a mobile element which moves with the key and is characterized in that at least said element mobile and said key on their mutual contact surface have a magnetic element and a cooperating magnetic or magnetizable element whose mutual attraction is thus determined, that in use normal, the end of said movable element remains in contact with the key.

Advantageously, the movable element is guided in a rectilinear manner relative to the body, for example by means of a needle on which it slides, substantially in the direction of the lifting movement and lowering the piano keys. This solution is very simple therefore reliable, inexpensive and makes it possible to produce a mobile element with low dimensions therefore very light (about 0.4 gram, in a realization put in use), in particular if it is made of polymer, such as for example a polyacetal. The device will thus not constitute a gene for the pianist who will hardly feel its presence under the keys.

To facilitate disassembly of the keyboard formed by the keys of the piano, the movable element may have a protruding rim and the body a shoulder limiting the sliding movement which tends to push out said movable element of the needle. The device thus produced then constitutes an inseparable entity which does not risk undesirable dismantling.

Another problem is to position the flap relative to the beam emitted by the emitting diode. For this, the mobile element can be of parallelepiped shape, one side moving in abutment against the body so as to obtain a simple translational movement (without rotation) of the flap, and said flap may be retained in a slot made on another face of the movable element or protrude, that is to say come in one piece with the movable element. Thus, the movement of the shutter will be a fair reflection of the movement of the button via the movable element and the connection between the flap and the mobile element will be simple, reliable and inexpensive.

• la figure 1 montre un clavier de piano standard vu de dessus,
• la figure 2 montre une vue d'ensemble, suivant la ligne II-II de la figure 1, du dispositif de l'invention placé sous le clavier du piano,
• la figure 3 montre en perspective le dispositif de l'invention,
• la figure 4 est une vue agrandie du dispositif tel qu'illustré en figure 2 ; il est représenté en trait fort en position repos touche levée et en trait mixte fin dans la position touche enfoncée,
• la figure 5 est une vue en coupe du dispositif selon le plan V-V de la figure 4,
• la figure 6 montre, de façon similaire à la figure 4, une variante de montage,
• la figure 7 montre une vue d'ensemble du dispositif placé sous le clavier d'un piano standard et selon une autre variante,
• la figure 8 est une vue de côté du dispositif isolé et agrandi de la figure 7 ; il y est représenté en trait fort dans la position touche levée ou en position repos, et en trait mixte fin, dans la position touche enfoncée,
• les figures 9, 10 et 11 sont des vues de côté du dispositif des figures 7 et 8 autour de la zone de contact, suivant trois variantes de réalisation selon lesquelles :
• la figure 9 montre un aimant collé sur la surface externe de la partie effilée du levier en contact avec une plaque métallique collée sur la face inférieure de la touche,
• la figure 10 montre un aimant collé sur la surface externe de la partie effilée du levier en contact avec une plaque métallique noyée dans la partie inférieure de la touche,
• la figure 11 montre un aimant collé sur la face inférieure de la touche en contact avec la partie effilée du levier, celui-ci étant alors métallique,
• la figure 12 montre une vue en perspective d'un aimant noyé dans la partie effilée du levier.

Other characteristics, objects or advantages of the invention will appear more clearly with the aid of the description which follows, made with reference to the appended drawings in which:

• FIG. 1 shows a standard piano keyboard seen from above,
• FIG. 2 shows an overall view, along line II-II of FIG. 1, of the device of the invention placed under the keyboard of the piano,
• FIG. 3 shows in perspective the device of the invention,
• Figure 4 is an enlarged view of the device as illustrated in Figure 2; it is shown in heavy lines in the raised key rest position and in thin dashed lines in the pressed key position,
• FIG. 5 is a sectional view of the device according to the plane VV of FIG. 4,
• FIG. 6 shows, in a similar manner to FIG. 4, an alternative mounting,
• FIG. 7 shows an overall view of the device placed under the keyboard of a standard piano and according to another variant,
• Figure 8 is a side view of the isolated and enlarged device of Figure 7; it is shown there in a strong line in the raised key position or in the rest position, and in a thin dashed line in the pressed key position,
• FIGS. 9, 10 and 11 are side views of the device in FIGS. 7 and 8 around the contact area, according to three alternative embodiments according to which:
• FIG. 9 shows a magnet bonded to the external surface of the tapered part of the lever in contact with a metal plate bonded to the underside of the key,
• FIG. 10 shows a magnet bonded to the external surface of the tapered part of the lever in contact with a metal plate embedded in the lower part of the key,
• FIG. 11 shows a magnet bonded to the underside of the button in contact with the tapered part of the lever, the latter then being metallic,
• Figure 12 shows a perspective view of a magnet embedded in the tapered portion of the lever.

In Figures 1 and 2, the keys 2, 2 'of a keyboard 4 under which the device of the invention is placed. The whole keyboard 4 is supported by a tray 8. A strip 6, called a small door, generally in short precious wood across the width of the keyboard, in front of the keys 2 which it hides at the bottom. Two points 10 guide the keys 2 in their movement between the pressed and released positions. This assembly is classic.

In Figures 3 to 5, we can see more precisely the device 1 of the invention. In order not to overload the drawings unnecessarily, three sensors having been represented, the marks have very often been worn only on one them in Figures 3 and 5. The undersides 3 of the keys 2, arranged side by side side by side, are in contact with one end 11 of movable elements 12 positioned respectively under each of the keys via of magnetic elements and of magnetic or magnetizable elements 14, 16 arranged under the keys 2 and on the movable elements 12. The element magnetic may be constituted by a magnet while the element magnetizable can be metallic or ferromagnetic material. They may be arranged indistinctly on the movable element or under the touch the piano without modifying the invention.

These movable elements 12 have attached to them a flap 20, here inserted into a slot 22 holding it relative to its movable element respective. The shutter could also be obtained from the element mobile advantageously made of plastic such as for example a polyacetal.

Said movable elements 12, which are advantageously shaped rectangular parallelepiped, have a rim 13 of rectangular shape in the lower part and a recess 15 made hollow to receive sliding a guide needle 18.

ns slide, thus on aligned needles 18, directed in the same direction (substantially vertical), and fixed on a body 24, 26 arranged on stage 8 of the piano. This body comprises a rail 24 presenting substantially in the form of a U-shaped profile and a plate 26 fixed to the rail 24, covering the device and having openings 34 through which pass the moving elements 12.

A support console 28 is also attached to the rail 24. console 28 maintains a light emitting diode 30a, a diode receiver 30b, and an electronic card 32 for processing information.

In practice, depending on the movement of the keys 2, the respective mobile elements 12 translate according to a movement straight, substantially in the direction of movement of the keys 2 (substantially vertical) when lowered or raised. They are guided in their movement on the one hand by the sliding needles 18 in the housings 15 and the openings 34 made in the plate 26 of the body, and on the other hand by a lateral face 36 of the rail 24 against which the edges 13 come to bear. The rectangular shape of the edges 13 prevents rotation of the movable elements 12 while the needles 18 and the openings 34 ensure their axial guidance with the cooperating parts of these elements.

Rotation can also be prevented by planning correspondence, in place of needle 18, a rod of non-circular section cooperating with a housing 15 in the movable element also of section not circular.

The flaps 20 linked to the mobile elements 12 will follow their movement and move between the emitting diodes 30a and receiving 30b. In the illustrated embodiment this amounts to cutting the beam more or less incident from the emitting diode 30a and thus modify the characteristics noted by the receiving diode 30b and then analyzed by the card electronic 32.

Other known systems can also be used such as the use of a slot made in the flap causing displacement of a light beam passing through the slit detected by a sensor on the other side of the shutter. The transmitter and receiver could also be placed from the same side of the flap 20 and detect, for example the displacement of lines of the "barcode" type produced on the shutter.

On the other hand, during disassembly of the keyboard 4, the elements mobile 12 following the movement of the keys 2 will rise. The openings 34 formed in the plate 26 forming the shoulder then go cooperate with the projecting edges 13 of the movable elements 12 to retain these and prevent them from coming out of the needles 18.

Although a magnet has been provided as a magnetic element, could replace the magnet with an electromagnet by providing a proper nutrition. In this case, when the electromagnet is not powered up, the device would be put out of action and the piano could be used traditionally, the movable elements being separated from the keys and resting on the rail.

In the variant embodiment illustrated in FIG. 6, so that obtain substantially the same length of travel stroke, the flaps 20, 20 'of the white 2 and black 2' keys respectively, which do not have the same length, two devices 1, 1 'have been arranged one behind the other displacement sensors according to the invention.

The sensor device 1 is used for the white keys 2, the sensor device 1 'is used for the black keys 2'.

A slightly wider single rail 124 replaces rail 24 of the previous figures; it is capped (on the right) in the figure by a plate 126 for guiding the mobile elements of the device 1 and (on the left, in the figure), by another plate 126 'for guiding the mobile elements of the device 1 '.

This arrangement also has the advantage of facilitating mounting and the distribution of sensor elements under the piano keys.

In FIG. 6, the black key 2 ′ has been indicated as pressed, while white key 2 has been marked as raised.

For the remainder, the assembly not being modified compared to what has been described in the previous figures, no further description will be given detailed.

In Figure 7, there is shown a keyboard provided with the device, seen from cut side. The plate 101 is a plate which supports the entire keyboard. The small door 102 is a strip, generally made of precious wood, running across the width of the keyboard, intended to hide the bottom of the keys. The key 103 is held by two guide tips 104. The lever 105 is a advantageously light tilting part and provided with a flap 106 which comes shut off part of the light beam from the optoelectronic system 107, which is not part of the invention.

Figure 8 shows the device more precisely. Leverage 105 has a tapered portion 107 whose curvature allows contact continuous tangential with the underside 111 of the key 103 by through the magnetic elements 112, 113. This lever is mounted on a pivot axis 109 and has a massive part 108 placed in such a way so that it is a counterweight to the tapered part 107; that is to say that the tapered part 107 and the massive part 108 are placed on either side of the pivot axis 109. An adjustment screw 110, placed at the end of the massive part 108 so as to be distant from the pivot axis 109, adjusts the component due to the gravitation of the contact force between the tapered part 107 of the lever 105 and the underside 111 of the button 108. We can thus regulate at will the negative action of lightening or the action positive weighting of the lever acting on the key to adjust the force to depress the touch as desired by the user.

The representation of the device in strong lines in the key position lifted and in a dashed line in the depressed key position shows the displacement of the contact surface between the underside 111 of the key 103 and the tapered part 107 of the lever 105.

Figures 9 to 12 illustrate different embodiments allowing the contact between the underside 111 of the key 103 and the tapered part 107 of the lever 105 via a magnetic and / or magnetizable element (magnet / ferromagnetic surface).

One embodiment consists in sticking to the tapered part 107 of the lever 105 a magnet 113 and stick a metal plate 112 on the underside 111 of the key 103 as shown in FIG. 9.

Another embodiment consists in drowning the metal plate 112 in a recess 114 made for this purpose in the lower part of the key 103 as shown in Figure 10.

Another embodiment consists of sticking to the underside 111 of the key 103 a magnet, this one being or not drowned in a recess made for this purpose in the key 103, and to realize the lever 105 in material metallic, ferromagnetic or magnetizable such as an iron blade or of steel, as shown in FIG. 11. Another embodiment consists in drown the magnet 116 in the tapered part 107 of the lever 105, advantageously by means of a trapezoidal groove 117 as shown in FIG. 12.

Of course, other implementations of the present invention could have been considered without departing from the scope of this invention. Any other device enabling the characteristics of displacement of the movable element 12 in translation relative to the needle 18, or respectively of the lever 105 in rotation relative to the axis 109, as in particular that an induction device would also be suitable.

Claims (14)

1. Device forming a displacement sensor used especially in an optoelectronic system for analysis of the movement of the keys (2, 2', 103) of a piano, characterized in that in order to track the movement of lowering/raising of the key, it comprises, fixed beneath the lower face (3, 3', 111) of each key (2, 2', 103), a magnetic or magnetizable element (14, 112, 115) which co-operates with a complementary magnetic or magnetizable element (16, 107, 113, 115, 116) linked to a mechanical element for analysis of the modification of a characteristic of the system, such as a movable shutter (20, 106), when an optoelectronic system is used, the said co-operating magnetic or magnetizable elements remaining in permanent mutual contact during normal operation of the device.
2. Device according to Claim 1, characterized in that, comprising a body (24, 26, 124, 126, 126') intended to be fixed to the piano, beneath the keys (2, 2'), and at least one element (12) movable relative to the body (24, 26, 124, 126, 126'), having one end (11) in contact with the lower face (3, 3') of a piano key (2, 2'), at least the said movable element (12) and the said key (2, 2') have on their mutual contact surface a magnetic element (14, 16) and a co-operating magnetic or magnetizable element (14, 16), the mutual attraction force of which is determined in such a manner that in normal use the end (11) of the said movable element (12) remains in contact with the key (2,
3. Device according to Claim 2, characterized in that the movable element (12) is guided rectilinearly relative to the body (24, 26), substantially in the direction of the movement of raising and lowering of the keys (2) of the piano.
4. Device according to Claim 3, characterized in that the movable element (12) slides on a pin (18) fixed to the body (24, 26).
5. Device according to Claim 4, characterized in that the movable element (12) has a projecting flange (13) and the body (24, 26) a shoulder (26) to limit the sliding movement of the said movable element (12) in the direction which tends to cause it to leave the pin (18).
6. Device according to one of the preceding claims, characterized in that the magnetic element (14, 16) is a magnet.
7. Device according to one of the preceding claims, characterized in that the magnetic element (14, 16) is an electromagnet.
8. Device according to any one of Claims 2 to 7, characterized in that the movable element (12) is generally in the shape of a rectangular parallelepiped, one lateral face being displaced while bearing against the body (24), and includes a shutter (20) projecting in another face.
9. Device according to any one of Claims 2 to 7, characterized in that the movable element (12) is generally in the shape of a rectangular parallelepiped, one lateral face being displaced while bearing against the body (24), and includes a slot (22) provided in another face to receive a shutter (20).
10. Device according to any one cf Claims 2 to 9, characterized in that the body is in the form of an elongate rail (24, 124) of constant section, to which are fixed aligned pins (18), pointing in the same direction, on which slide the movable elements (12).
11. Device according to Claim 10, characterized in that it additionally comprises a plate (26, 126, 126') which caps it and through which the movable elements (12) pass in order to guide them in their movement and prevent them leaving the pin (18).
12. Device according to Claim 1, characterized in that, the displacement sensor having a lever (105) mounted on a pivot axis (109), the said lever has a tapered end (107) in continuous tangential contact with the lower face (111) of a piano key (103), the said lever (105) and/or the said key (106) having on their mutual contact surface a magnetic element and a co-operating magnetic or magnetizable element (107, 112, 113, 115, 116).
13. Device according to Claim 12, characterized in that the said lever (105) has on the opposite side (108) from the said contact zone with respect to the pivot axis (109) a balancing means, such as, especially, an adjustable screw (110).
14. Device according to Claim 10 or Claim 11, characterized in that it comprises two rows of sensor systems respectively (1, 1') placed one behind the other in the elongate rail (124) for analysis of the respective movements of the white keys (2) and the black keys (2').

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