JPH03168696A - Key driver for automatic keyboard musical instrument - Google Patents

Abstract

PURPOSE:To improve the accuracy of key touch/detach control and to decrease the noises at the time of key driving by providing a pair of coils perpendicularly to the driving direction of keys, yokes fixed thereto and a movable yoke suspended in the magnetic field generated by the same atop a rack. CONSTITUTION:A magnetic field is generated when a driving current is passed from a controller to the coils 1, 2. Driving force is then generated between the stationary yokes 1A, 2A and the movable yoke 3. There is a window 5 in the movable yoke 3 and the area facing the stationary yokes 1A, 2A is variable. The left side of the yoke 3 receives the pushing down force F1 and the right side receives the pushing up force F2 when the coil 1 is energized. The key 73 (74) fixed to the yokes 1A, 2A is driven by the balance of the F1, F2. The gap change ratio of the yoke 3A with respect to the yokes 1A, 2A is maintained constant by the open window 5 even if the lifting position of the key varies and, therefore, the thrust of the key remains approximately constant unless the energizing current is changed. The control accuracy to the key is improved and the noises at the time of the key driving are decreased.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a key drive device for an automatic keyboard instrument, and more specifically, it improves the precision of key press/release control and reduces noise during key drive. This invention relates to a key drive device for an automatic keyboard instrument.

"Prior Art" An automatic keyboard instrument (for example, a player piano, etc.) is equipped with a key drive device for performing automatic performance based on performance information recorded in advance or performance information supplied from the outside.

FIG. 8 shows an example. The player piano 7l in the figure has a keyboard composed of a plurality of white keys 73 and black keys 74,
A string-striking mechanism 77 that transmits the movement of each key 73, 74 to the hammer 75, a string 79 that is struck by the hammer 75, and a string 79.
It has a damper 78 for suppressing vibrations.

A shelf board 84 is provided below the white key 73 or the black key 74, and a reed center 80 and a reed front 82 are fixed to the upper surface of the shelf board 84. The keys 73 and 74 are attached to be swingable around a balance pin 81 provided at the upper part of the reed center 80. Furthermore, an oval keybin 85 protrudes from the lower surface of the front side of the keys 73 and 74 toward the front of the reed 82, and this oval keybin 85 is loosely fitted into a recess 82a provided on the upper surface of the front of the reed 82. This prevents the keys 73 and 74 from wobbling laterally. In addition, the key 73 is located at the back of the upper surface of the shelf board 84.
A push type solenoid 83 is provided below. When the solenoid 83 is activated, the plunger 83a of the solenoid 83 projects and pushes up the vicinity of the lower part of the win pen 86 of the key 73 (74) to rotate the key 73,74.

This movement is transmitted to the hammer 75 and damper 78 via the string-striking mechanism 77. As a result, the damper 78 separates from the string 79, and the hammer 75 rotates to the left in the drawing, thereby striking the string. The above operations are performed continuously based on the output signal from the control unit 90, thereby performing automatic performance.

In addition, 87 is a key holding member for pressing the part above the balance bin 8l of the white key 73 or black key 74, and when the middle part of #73.74 is pushed upward by the solenoid 83, the key lifts up. This is to prevent

"Problems to be Solved by the Invention" By the way, the above-described conventional key drive device for an automatic keyboard instrument has the following drawbacks.

(2) Noise is generated when the solenoid 83 operates and the plunger 83a slides, when the tip of the plunger 83a comes into contact with the lower surface of the keys 73 and 74, and when the plunger 83a returns to the final sliding stroke position.

■ Due to the sliding of the plunger 83a, etc., the plunger 8
3a itself or the lower surfaces of the keys 73 and 74 may be worn out or damaged, resulting in poor reliability and durability.

■ The keys 73, 7 are released by the solenoid plunger 83a.
By pushing up near the bottom of the wippen 86 of No. 4, the key 73.
74, and since the point of application of the force is different from when played by a pianist, faithful reproduction is difficult.

■When the tip of the plunger 83a comes into contact with the bottom surface of the keys 73 and 74, it is difficult to reproduce the delicate playing techniques of a pianist using the so-called impact drive method. For this reason, for example, it is impossible to reproduce the so-called har-7 key technique, in which only the lower half of the key is used and the stroke is less than about 5 mm, or a continuous-strike performance.

■ With impact drive, it is difficult to perform 7-effect back control by introducing a servo system, and there is a limit to the improvement of control accuracy.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a key drive device for an automatic keyboard instrument that can solve the various problems described above.

"Means for Solving the Problem" In order to achieve the object, in the structure recited in claim 1 of the present application, a device is provided between the middle of the reed and the front of the reed on the upper surface of the shelf of the automatic keyboard instrument. , a pair of coils each generating a magnetic field in accordance with the direction of the energized current in a direction substantially perpendicular to the swinging direction of the key provided above the shelf board, and a pair of fixed yokes each fixed to the coils. and at least one of the opposing area equivalent amount or the opposing interval of both parts fixed to the key and facing the pair of fixed yokes individually changes in opposite directions, and the pair of coil-o and the above-mentioned coil o. a movable yoke suspended in a magnetic field generated by the fixed yoke;
It is characterized by having the following.

Further, the structure according to claim 2 of the present application is characterized in that, in addition to the above structure, the pair of coils are arranged adjacent to each other.

Furthermore, in the structure according to claim 3 of the present application, the structure according to claim 1
In addition to the structure described above, the present invention is further characterized in that the pair of coils are arranged opposite to each other along the longitudinal direction of the key with the movable yoke sandwiched therebetween.

"Operation" In the structure according to claim 1, when the coil is energized, a magnetic field is generated through the solid yoke, and an attractive force is generated between the fixed yoke and the movable yoke. There is a pair of fixed yokes that exert forces in opposite directions on the movable yoke, and the movable yoke is moved by the difference between these forces. Eventually, the key fixed integrally with the movable yoke is returned upward or downward. Furthermore, by controlling the current flowing through the pair of coils, the driving direction and driving speed of the key can be controlled.

In the structure according to claim 2, since the pair of coils are arranged adjacent to each other, the coils can be arranged together on one side of the movable yoke, allowing for compact arrangement.

In the structure according to claim 3, since the pair of coils are arranged opposite to each other in the longitudinal direction of the key, a large arrangement space can be secured, and since sufficiently large coils can be arranged as individual coils, the key-pressing/key-releasing speed can be increased. be able to.

``Embodiment'' Hereinafter, an embodiment of the invention will be described with reference to the drawings. First Embodiment FIGS. 1(A) and 1(B) show a first embodiment of the present invention. In these figures, the same reference numerals are given to the structural elements corresponding to the parts shown in FIG. 8, and the explanation thereof will be omitted.

As shown in FIG. 1(a), the key drive device of this embodiment is
A pair of coils 1.2 disposed on the upper surface of the shelf board 84 between the middle 80 of the reed and the front 82 of the reed, and a pair of fixed yokes IA and 2A fixed to each of the coils 1.2. key 73
A movable yoke 3 fixed to the lower surface of (74) is provided.

The fixed yokes iA, 2A are U-shaped and made of ferromagnetic material, and are inserted in the longitudinal direction of the key 73 (74) with the movable yoke 3 sandwiched between them so that their openings 4 face each other. They are arranged facing each other with an appropriate interval between them. and,
The coil 1.2 is fixed to the central portion of the fixed yokes IA, 2A so as to generate a magnetic field directed in a direction substantially perpendicular to the direction of swing of the key 73 (74).

The movable yoke 3 is made of a ferromagnetic material and has a T-shaped cross section, and its upper flat portion 3a is fixed to the lower surface of the key 73 (74) with fixing means such as screws or adhesive. The lower upright portion 3b is designed so that the lower upright portion 3b is along the longitudinal direction of the key 73 (74) and can face the fixed yokes IA, 2A even when the key 73 (74) is not pressed. The lower ends thereof are provided so as to extend to near the lower ends of the fixed yokes IA and 2A. In addition, the lower standing part 3
Between the lower end of b and the shelf board 84, when the key is pressed, the key 7
3 (74) is left with a gap C that is large enough for it to go down.

Further, the movable yoke 3 is formed with a plurality of window openings 5 (5a, 5b), each having a different opening area, arranged in the vertical direction, and these are arranged in four rows on the left and right. In Fig. 1 (A), the window openings 5a in the two rows on the left side are bored so that the opening area gradually increases from the top to the bottom, while the window openings 5b in the two rows on the right side are in the opposite direction. Gradually from the bottom to the top, two rows of window holes 5a on the opening surface side and their vicinity face the fixed yoke IA on the left side in the figure, and two rows of window holes 5b on the left side and their vicinity. The vicinity faces the fixed yoke 2A on the right side. That is, the opposing area equivalent amounts of both the left and right portions of the movable yoke 3, which respectively face the pair of fixed yokes IA and 2A, are shaped such that they change in opposite directions.

Note that the coils 1 and 2 are electrically connected to the control unit described in the conventional example, and these coils 1 and 2 are electrically connected to the control unit described in the conventional example.
．． The value and direction of the current flowing through the two terminals are individually controlled.

Next, the operation of the key drive device having the above structure will be explained.

When a drive current flows from the control unit to the coils 1 and 2, a magnetic field is generated around the coils 1 and 2 according to the direction of the current, and a magnetic loop is created between the fixed yokes IA and 2A and the movable yoke 3. It is formed. And fixed yoke L
A driving force is generated between A, 2A and the movable yoke 3.

The movable yoke 3 facing these is also formed with window openings 5, so that the area facing the fixed yokes IA, 2A is variable. In FIG. 1, the left side of the movable yoke 3 is subjected to a force F which is pushed down by the energization of the coil 1. On the other hand, the right side of the movable yoke 3 receives an upward force F,
receive. The key 73 (74) ha to which the movable yoke 3 is fixed receives an upward or downward driving force by the balance of both forces Fr and Fz. Moreover, the speed is determined by the amount of current supplied to the coil 1.2.

Further, the force for pushing up or lowering the key 73 (74) described above is obtained by the magnetic force generated between the fixed yokes IA, 2A and the movable yoke 3, and the force (thrust) is Fixed yoke IA even if the vertical position of
Since the air gap change rate of the movable yoke 3 with respect to 2A is kept constant (as described above, this is because multiple window openings 5 and
. . ) is maintained approximately constant unless the value of the applied current is changed (see FIG. 7). In this way, the key press and key release strength characteristics are flat, so
The control accuracy for 673 (74) is improved.

This is because a movable yoke made of a high permeability material such as a piece of iron is placed in the magnetic field, and a force is always applied to the movable yoke in a direction that minimizes the magnetic resistance of its magnetic path.

Note that a modification of the first embodiment will be shown below.

FIGS. 2(a) and 2(b) show other examples of the movable yoke 3.

That is, in the above example, although the opposing areas of the left and right portions of the movable yoke 3 facing the fixed yokes LA and 2A are varied,
A plurality of window openings 5 (5) of different sizes are provided in the lower standing portion 3b.
a, 5b), etc., but here, instead of that, the problem is dealt with by making the end face of the lower upright portion 3b slope. The direction of inclination is the same at both the left and right ends, and the lower upright portion 3b has a parallelogram shape when viewed from the side.

Even with such a structure, when the coil 1.2 is energized, the movable yoke 3 receives thrust in the vertically opposite direction from the left and right fixed yokes IA and 2A, and the current supplied to both coils 1.2 is controlled. This allows you to press and release keys. In addition, with such a structure, the machining of the movable yoke 3 becomes easy and costs can be reduced.

31st! 1 (a) and (b) show still other examples of the movable yoke 3.

In this example, two triangular window openings 5.5 each having a size that fits approximately half the size of the lower upright portion 3b are formed in the upper and lower directions opposite to each other.

With such a structure, it is possible to vary the opposing areas of the left and right sides of the fixed yoke IA and the movable yokes facing each other for two people, and by controlling the current supplied to the coil 1.2, keystrokes and keystrokes can be controlled. Can be operated.

FIG. 4 shows another example of the movable yoke 3 and the corresponding fixed yokes LA, 2A.

In this example, the movable yoke 3 is divided into two halves and wedge-shaped with respect to each other, and the divided movable yokes 3A and 3B are disposed offset in the longitudinal direction of the key 73 (74). The front movable yoke 3A is arranged so that its lower side is thicker, and the rear movable yoke 3B is arranged so that its upper side is thicker.

The pair of fixed yokes LA and 2A are also movable yokes 3A and 3B.
The keys 73 (74) are arranged so as to be shifted in the longitudinal direction of the keys 73 (74). The front fixed yoke 2A has two wedge-shaped bodies 2Aa, 2Aa made of ferromagnetic material arranged parallel to each other with an interval left and right, and the upper interval is increasing, and the rear fixed yoke IA has two wedge-shaped bodies 2Aa, 2Aa made of ferromagnetic material. Wedge-shaped body IAa, IAa
are arranged parallel to each other with intervals left and right, and the distance above is reduced.

As a result, when the movable yoke 3 moves downward together with the key 73, the cross-sectional area of the movable yoke 3A that crosses the magnetic field generated from the front fixed yoke 2A becomes smaller, while the magnetic field generated from the rear fixed yoke IA decreases. The cross-sectional area of the movable yoke 3B becomes larger.

In this way, the fixed yoke IA of the movable yoke 3. Since the amount equivalent to the area facing 2A changes in the opposite direction, a thrust force in the vertically opposite direction acts on the movable yokes 3A and 3B as in the above example, and the current supplied to both coils 1.2 is controlled. This allows you to press and release keys.

Second Embodiment FIGS. 5(a), (b), and (c) show a second embodiment of the present invention. In the drawings, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted.

As shown in the figure, in this embodiment, the movable yoke 3 is arranged such that the lower upright portion 3b thereof is inclined from the vertical plane.
4) The upper flat part 3a is screwed to the lower surface, while the pair of fixed yokes IA and 2A are arranged with a slight interval along the longitudinal direction of the key 73 (74) so as to sandwich the movable yoke 3. has been done.

The fixed yoke IA (2A) has a pair of ferromagnetic plates IAa, IAa as shown in FIG. 5, and a coil l (2) is installed between these ferromagnetic plates IAa, IAa. A common shaft yoke 8 is inserted through the central portion in the interposed state. The end face of the fixed yoke IA (2A) facing the movable yoke 3 is inclined to the same extent as the movable yoke 3.

In this way, the lower upright portion 3b of the movable yoke 3, the fixed yoke IA (2A) facing it, and the ferromagnetic plate material IAa
, IAa are inclined because of the vertical force F that attracts the movable yoke 3 due to the magnetic field generated between the pair of fixed yokes IA and 2A, as shown in FIG. This is to obtain power. Here, by changing the angle of this movable yoke 3, the thrust characteristics with respect to the stroke can be adjusted.

In this embodiment, when the key 73 (74) moves downward, the distance between the movable yoke 3 and the fixed yoke 2A on the right side of the figure narrows (gap reduction), the downward suction force increases, and as a result, the downward thrust On the other hand, conversely, the distance between the movable yoke 3 and the left fixed yoke 1A widens (gap enlargement).
, the upward suction force decreases and, as a result, the upward thrust force also decreases.

Since the opposing spatial gap (gap) between the movable yoke 3 facing the fixed yokes LA and 2A changes in this way, the movable yoke 3, a thrust force is applied in the upside down direction, allowing keystrokes and keystrokes to be performed.

Furthermore, in this embodiment, the movable yoke 3 can be obtained by simply bending a rectangular ferromagnetic plate material, and the structure is simplified, resulting in cost reduction.

In addition, the fixed yoke LA (2A) is installed on the shelf board 84.
Since the common shaft 7 and yoke 8 are used here, 8
Eight keys can be installed at once. Also, at this time, there is a concern that the fixed yoke LA (2A) may shift from side to side (in the axial direction of the common shaft yoke 8) with respect to the movable yoke 3, but even if it shifts to some extent, the forces acting on the movable yoke 3 will be opposite to each other. Because the balance is maintained by both coils 1 and 2, there is little effect on key-pressing and key-release operations.

Third embodiment show.

In this embodiment, the coils 1.2 fixed to the shelf board 84 are assembled to one side (front side) of the movable yoke 3, and are assembled so that every other coil generates a magnetic field in the opposite direction. In accordance with this, the fixed yokes IA and 2A are also arranged parallel to each other at approximately half the interval as compared to the above embodiment.

The above coil 1.2 is as shown in Fig. 6 (opening).
Two pieces are integrally incorporated into the coil bobbin 10;
something is being used. With such a coil, the work of winding the coil is easy and the work of assembling it into the shelf board 84 can also be easily performed. In addition, from this integrated coil bobbin lO, 3
Book terminals T extend, one of which is used as a common terminal.

On the other hand, in the movable yoke 3, an L-shaped support plate portion 3l is fixed to the lower surface of the key 73 (74) with fixing means such as screws, and both left and right ends of the upright portion 31a of the L-shaped support plate portion 31 are fixed to the lower surface of the key 73 (74). is supported by triangular plate portions 32 and 33, and the fixed yoke IA. 2A
It is located between the ferromagnetic plates.

Moreover, they are provided so that their inclined end faces are in opposite directions.

Also in this embodiment, when the coil 1.2 is energized and, for example, the key 73 (74) moves downward, the area of the movable yoke 3 facing the fixed yoke IA becomes smaller;
On the contrary, the area facing the other fixed yoke 2A becomes large.

Since the opposing cross-sectional area of the movable yoke 3 with respect to the fixed yokes IA and 2A changes in the opposite direction, a thrust force is applied to the movable yoke 3 in the opposite direction, as in the above example, and both coils 1 and 2 By controlling the current supplied to the keypad, key-pressing and key-release operations can be performed.

Furthermore, in this embodiment, the fixed yoke IA (2A) and the coils 1 and 2 can be arranged together on one side of the movable yoke 3, which provides the advantage of being able to be assembled compactly.

"Effect of the invention" According to the structure described in claim 1, the following effects are achieved.

■ Almost no noise is generated because it is a non-contact drive method rather than a contact drive method (impact method) using a plunger or the like.

■ Also, since there are no mechanical contact parts, reliability and durability are improved.

(2) Since differential control is performed using a pair of coils, and the movable yoke and key are integrated, not only key-pressing but also key-release operations can be controlled, expanding the control range and improving control accuracy. This makes it possible to reproduce the 1-7 keys and improve the performance of repeated hits.

Furthermore, since the equivalent amount of the area of the movable yoke facing the fixed yoke is variable, the thrust force characteristics with respect to the movement stroke are flat compared to the conventional impact method. Therefore, reproducibility is particularly improved in the low-speed drive range (during soft tone reproduction, pianissimo performance).

(2) As described above, since the key is differentially controlled by a pair of coils, the key can be controlled at all times according to the supplied current regardless of the position of the key, so controllability is extremely good when performing 7 feedback control.

For example, if a permanent magnet is incorporated in the magnetic circuit, it can also be used as a key speed detection sensor by time-divisionally extracting the coil output voltage when the movable yoke crosses the magnetic field.

Also, according to the structure of claim 2, in addition to the above-mentioned effects, since the pair of coils are arranged adjacent to each other, the coils can be arranged together on one side of the movable yoke, and a compact arrangement is possible. Therefore, assembly and adjustment workability is improved.

Furthermore, according to the structure described in claim 3, since the pair of coils are arranged opposite to each other in the longitudinal direction of the key, a large space for arranging the coils and the magnetic circuit can be secured, and each coil can be sufficiently large. can be placed and can exert a strong force on the key.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, FIG. 1 (A) is a side view of the main part of the key drive device, and FIG.
FIG. 2 shows a modification of the movable yoke in the first embodiment, FIG. Furthermore, another modification is shown, and FIG. 3 (a) is a side view;
4 is a perspective view showing another example of a combination of a fixed yoke and a movable yoke. FIG. FIG. 5 shows a second embodiment of the present invention, in which (A) is a side view of the main part of the key drive device, (opening) is a perspective view of the main part, and (C) is an enlarged view of the main part. It is an explanatory diagram. FIG. 6 shows a third embodiment of the present invention, in which FIG. 6(a) is a perspective view of the main part of the key drive device, and FIG. 6(b) is a detailed perspective view of the coil. FIG. 7 is an explanatory diagram illustrating the operational characteristics of the key of the key drive device according to the present invention. FIG. 8 is a side sectional view of a conventional key drive device for an automatic keyboard instrument. 1.2... Coil A, 2A... Fixed yoke... Movable yoke 3... White key 4... Black key 0...・・・・・・Reed middle 2・・・・・・Reed front 4・・・Shelf board

Claims (1)

[Scope of Claims] 1) Disposed between the middle of the reed and the front of the reed on the upper surface of the shelf of an automatic keyboard instrument, in a direction substantially perpendicular to the swinging direction of the keys provided above the shelf. , a pair of coils each generating a magnetic field according to the direction of the energized current, a pair of fixed yokes fixed to the coils, and both parts fixed to the key and facing the pair of fixed yokes individually. The shape is such that at least one of the facing area equivalent amount or the facing interval changes in opposite directions,
A key drive device for an automatic keyboard instrument, comprising: a movable yoke suspended in a magnetic field generated by the pair of coils and the fixed yoke. 2) The key drive device for an automatic keyboard instrument according to claim 1, wherein the pair of coils are arranged adjacent to each other. 3) The key drive device for an automatic keyboard instrument according to claim 2, wherein the pair of coils are arranged opposite to each other along the longitudinal direction of the key with the movable yoke in between.