JPH03168697A - Key driver for automatic keyboard musical instrument - Google Patents

Abstract

PURPOSE:To improve the accuracy of key touch/detach control and to decrease the noise at the time of key driving by providing a coil in the direction orthogonal with the oscillation direction of a key, a movable yoke opened on the rear surface of the key and a stationary yoke varying in the area facing the movable yoke along the oscillation direction of the key, atop a rack. CONSTITUTION:Attraction force is generated between the stationary yoke 2 and the movable yoke 3 and the key 73 (74) is attracted together with the yoke, etc., downward when a driving current is passed from a controller to the coil 1. The change in the attraction force can flatten the characteristic of the key thrust by a difference in the lifting position of the key 73 (74) when the angle theta of the taper T of upright plates 2b, 2c of the stationary yoke 3 is set at a proper value while the coil current is constant. Since a space S is formed at the center of the body 3b of the yoke 3, a magnetic vector F is generated along the oscillation direction of the key 73 (74) between the yokes 2 and 3. The key is surely actuated in the oscillation direction by effectively utilizing the perpendicular component F1 thereof, by which the operation control accuracy of the key is improved and the noises at the time of the key driving are decreased.

Description

[Detailed Description of the Invention] "Industrial Field of Application J The present invention relates to a key drive device for an automatic keyboard instrument. Specifically, the accuracy of key press/release control is improved and the noise during key drive is reduced. This invention relates to a key drive device for an automatic keyboard instrument.

"Junioru's Technology" Automatic keyboard instruments (for example, player pianos, etc.) have a built-in key drive device for automatic performance based on pre-recorded performance information 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 bin 81 provided at the top of the reed center 80. Further, an oval key pin 85 is provided on the lower surface of the front side of the keys 73, 74 upwardly from the front side 82. The oval key pin 85 is loosely fitted into the insertion hole on the back of the key, thereby preventing the keys 73 and 74 from wobbling laterally. Further, a push-type solenoid 83 is provided at the back of the upper surface of the shelf board 84 and below the key 73.

When the solenoid 83 is activated, the plunger 83a of the solenoid 83 protrudes and the win vent 8 of the key 73 (74)
6. Push up the vicinity of the lower part to rotate the keys 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 to strike the string. The above operations are performed in tandem based on the output signal from the control unit 90, thereby performing automatic performance.

Reference numeral 87 is a key holding member for pressing the white key 73 or the black key 74 above the balance bin 81, and prevents the key from lifting when the lower part of the key 73 or 74 is pushed upward by the solenoid 83. This is to prevent this.

"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 key 73, 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 key 73.7 is released by the plunger 83a of the solenoid.
Key 73. by pushing up near the bottom of Wiven 86 of No. 4.
74, and since the point of application of the force is different from when a pianist plays, it is difficult to achieve faithful reproduction.

■ In the so-called impact drive method, in which the tip of the plunger 83a is brought into contact with the lower surface of the key 73.74,
It is difficult to reproduce the delicate playing techniques of a pianist. For this reason, it is not possible to reproduce the so-called 7-key technique, in which, for example, only half of the keys are used and the stroke is less than about 5 mm.

■ With impact drive, it is difficult to perform feedback control by introducing a servo system, etc., and there is a limit to improving control accuracy.

■ A keyboard pressing member 87 is required to prevent the keys 73 and 74 from lifting up when pushed up with the plunger 83a, but if the key holding member 87 is not in the appropriate position, the keys 73 and 74 will be pushed up.
The oscillation of 3.74 may not be performed as desired, which may result in poor sound production.

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 Problems" In order to achieve the above object, the present invention provides an automatic keyboard instrument with an automatic keyboard instrument, which is arranged between the inside of the reed and the front of the reed on the upper surface of the shelf board, and is provided above the shelf board. a coil that generates a magnetic field in a direction substantially perpendicular to the rocking direction of the key; a movable yoke that is fixed to the lower surface of the key and has a hollow portion that opens at the lower end; , a fixed yoke fixed to the coil at a position closely facing the movable yoke and formed in a shape such that a relative amount of the area facing the movable yoke changes along the swing direction of the key. It is characterized by:

"Operation" In the present invention, when the coil is energized, a magnetic field is generated through the fixed yoke, and an attractive force is generated between the fixed yoke and the movable yoke. Here, since the fixed yoke and the movable yoke have a variable relative amount of opposing area, the relative distance between the two and the suction characteristics can be set arbitrarily.

Therefore, it is possible to set the attraction characteristic with respect to the rocking position of the key to a flat characteristic that is easy to control, and the key driving force can be controlled by adjusting the amount of current supplied to the coil.

``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 respective components corresponding to the respective parts 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 coil l, a fixed yoke 2 fixed to the coil l, and a coil l fixed to the lower surface of the key 73 (74) are arranged on the upper surface of the shelf board 84 and between the reed center 80 and the reed front 82. t; A movable yoke 3 is provided.

The coil l is arranged so as to generate a magnetic field in a direction substantially perpendicular to the swinging direction of the key 73 (74) when energized.

The fixed yoke 2 is fixed at a position close to and facing the movable yoke 3, and is formed in a shape such that the relative amount of the area facing the movable yoke 3 changes along the swing direction of the key 73 (74). . Specifically, as shown in FIG.
The left and right upright plate portions 2b and 2c are formed into a substantially U-shaped cross section by the left and right upright plate portions 2b and 2c, and are erected at appropriate intervals on both sides of a with the coil 1 sandwiched between them.
．． The upper inner surface of 2c is formed with a tapered portion T that widens upward and outward.

The movable yoke 3 includes a mounting plate portion 3a fixed to the lower surface of the wooden key 73 (74) by fixing means such as screws, and a hollow portion S attached to the lower surface of the mounting plate portion 3a.
The yoke main body 3b has a U-shaped cross section and is attached such that the opening thereof faces downward.

The yoke body 3b has a corresponding coil 1 and fixed yoke 2.
It is positioned coaxially with the Further, the yoke main body 3b is pushed down and the left and right upright plate portions 2b of the fixed yoke 2 are pushed down. 2c so as not to interfere with the plate portions 2b. The radius "a" is determined so that a certain gap is formed between it and 2C and it is located inside the gap. Additionally, a key 73 is provided between the movable yoke 3 and the coil 1.
(74) is left with a gap C large enough to allow the key to fall even when pressed down. Note that the fixed yoke 2 and movable yoke 3 are each made of a ferromagnetic material.

Further, the coils l are electrically connected to the control unit described in the conventional example, so that the value and direction of the current flowing through the coils l are individually controlled.

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

When a current flows from the control unit to the coil 1, a magnetic field is generated around the coil 1 according to the direction of the current, and a magnetic loop is formed between the fixed yoke 2 and the movable yoke 3. Then, an attractive force is generated between the fixed yoke 2 and the movable yoke 3. Due to this suction force, the key 73 (74) is attracted downward together with the movable yoke 3.

The attraction force at this time is the coil! It is determined by the value of the current supplied to.

This is caused by the magnetic force generated between the yoke 2 and the movable yoke 3, and the force changes somewhat depending on the vertical position of the key 73 (74). This change in the attractive force is mainly determined by the angle θ of the tapered portion T of the left and right upright plate portions 21) + 2c of the fixed yoke 2, assuming that the current applied to the coil is kept constant. Therefore, by setting this taper angle θ to an appropriate value, the key 7 can be
It is possible to flatten the characteristics of the key thrust due to the difference in the vertical position It (stroke) of 3 (74).

Furthermore, since a space S is formed in the center of the yoke body 3b of the movable yoke 3, a magnetic vector in the direction along the swinging direction of the key 73 (74) is generated between the movable yoke 3 and the fixed yoke 2. F is generated, and by effectively utilizing the vertical component F of this magnetic vector F, the key 73 (74) can be reliably operated in the swinging direction. By the way, when the movable yoke 3 is made solid without providing the hollow part S, the magnetic flux shield 3
This makes it difficult to raise and lower the key 73 (74).

In addition, the coil 1 is attached to the shelf board 84, which has the advantage that the wiring to the coil 1 is easier and easier to mount than when it is attached to the movable side, i.e., the jl73 (74) side.

A modified example is shown below. In addition, Figure 1 (a). The same reference numerals are given to the same structural elements as in the example shown in (mouth).

FIG. 1(C) shows another example of the movable yoke 3.

In the above example, the movable yoke 3 is composed of two members, but here, the movable yoke 3 is composed of one member having a U-shaped cross section. The movable yoke 3 can be easily obtained by drawing or extrusion. The outer side surface 31a of the upright portion 31 of the movable yoke 3 is the fixed yoke 3.
The tapered portion is shaped so as to become thinner toward the bottom in correspondence with the taper portion T of the tapered portion.

When such a movable yoke 3 is used, since the number of parts is reduced, manufacturing and installation man-hours are reduced, costs can be reduced, and quality control of parts can be easily controlled. In particular, since 88 keys are used on one piano, the above effect is significant.

FIG. 1(2) shows another example of the movable yoke 3.

The movable yoke 3 shown here is obtained by bending a plate material, and the upright portions 31 on both sides are shown in FIG.
Similar to the example shown in c), the outer side is bent over 90 degrees so that it goes inside. Even with such a structure, effects similar to those shown in FIGS. 1(A) to 1(C) can be obtained. FIG. 1(e) shows yet another example. In the movable yoke 3 shown here, a compression spring 5 is interposed between the upper surface of the coil 1 and the lower surface of the flat plate portion 3a of the movable yoke 3. By interposing the compression spring 5 in this way, the load of the extra movable yoke 3 can be removed, and even when the movable yoke 3 is attached in this way, the same key touch feeling as before it is attached can be obtained. Benefits can be obtained. Further, the dynamic characteristics of the key drive system can be adjusted by the compression spring 5, and the stability of the system during 7-effect back control can be increased.

Second example FIGS. 3A and 3B show a second embodiment of the present invention.

In the figure, the same reference numerals are given to the same components as those in FIG.

As shown in the figure, in this embodiment, serrated portions 2d are formed at the upper end portions of the upright plate portions 2b and 2c that constitute the fixed yoke 2 fixed to the coil 1. On the other hand, the lower surfaces of the left and right upright portions 3l of the movable yoke 3 are formed with serrated portions 31d corresponding to the serrated portions 2d of the fixed yoke 2.

As a result, when the movable yoke 3 moves up and down with [73 (74)], the cross-sectional area (relative amount of opposing area) of the fixed yoke 2 corresponding to a fixed position of the movable yoke 3 changes. That is, in the first embodiment shown in FIG. 1 above, the fixed yoke 2
Left and right standing plate portions 2b. By changing the thickness of the movable yoke 2C, the relative amount of the opposing area with respect to the movable yoke 3 was varied, but in this embodiment, instead of that, the movable yoke 3
Opposed to. Note that the serrated portions 2d. of the fixed yoke 2 and the movable yoke 3. 31d is set so that the number of opposing inclined sides is an even number.

According to the above key drive device, when a drive current flows from the control unit to the coil 1, an attractive force acts between the fixed yoke 2 and the movable yoke 3, and the key 73 (74) moves downward. At this time, the distance between the movable yoke 3 and the fixed yoke 2 becomes narrower, and the cross-sectional area (corresponding to the opposing area) of the movable yoke 3 that crosses the magnetic field generated from the fixed yoke 2 changes to become larger. Since the relative amount of opposing areas between the fixed yoke 2 and the movable yoke 3 changes in this way, the key thrust characteristics accompanying the movement stroke of the movable yoke 3 are
By setting the inclination angles of d and 31d, it can be changed arbitrarily. Therefore, the serrated portions 2d, 31
By appropriately setting the inclination angle of d and adjusting the current supplied to the coil 1, key press/release control for the key 73 (74) integrated with the movable yoke 3 can be appropriately set. As shown in FIG. 4, relatively flat characteristics are obtained that facilitate key thrust control.

Note that since the number of inclined side surfaces forming the opposing serrated portions 2d and 31d of the fixed yoke 2 and the movable yoke 3 is an even number, although the vertical division of magnetic force effectively acts as thrust, the horizontal The directional components cancel each other out, and the horizontal component does not affect the key driving force.

FIG. 5 shows the hammer speed when the key is driven by the key drive devices shown in the first and second embodiments. In this way, by controlling the voltage applied to the coil, the hammer stringing speed can be varied.
Moreover, as is clear from the figure, since the string-striking speed changes in a nearly linear manner, it can be inferred that control can be easily performed.

FIG. 6 shows an example in which the key drive device shown in the second embodiment is actually attached to a keyboard instrument. As shown in these figures, the fixed yoke 2 is inserted into a common coil plate 21 and holes 21a formed at predetermined intervals along the length of the coil plate 21, and the lower end is screwed to the coil plate. 2
Standing plate 22 attached to the upper surface of l in an upright state...
It is being structured as such. The above common coil plate 2l is the sixth
As shown in the figure, it is fixed at a predetermined position on the keyboard instrument by being screwed to the shelf board 84 via the stay 23. A certain coil unit 1l is interposed between the upright plates 22 in the common coil plate 2l, with the film 1 built into the case 24.

On the other hand, the movable yoke 3 is directly screwed and fixed to the lower surface of the key 73 (74). Here, the thickness of the upright portion 31 of the movable yoke 3 is set to approximately half the thickness of the upright plate 22 of the fixed yoke 2, and two adjacent upright portions 31 have one common part. Fixed yoke standing plate 22
It is located above.

With this structure, the coil plate 2l of the fixed yoke 2
can be made into one by commonizing them, and the same upright plate 22 of the fixed yoke can also be used, which improves ease of assembly.
This is advantageous in terms of manufacturability.

Note that even if the movable yoke 3 is slightly shifted to the left or right with respect to the fixed yoke 2, the area of the substantially opposing portions remains almost the same, so that the key thrust control is not affected.

FIG. 7 shows an example of actually incorporating the key driving device according to the first embodiment shown in FIG. 1 into a keyboard instrument. In this example as well, a common plate member is used for the coil plate 2l of the fixed yoke 2, and the upright plate 22 is also made common, so that the same effect as shown in FIG. 6 can be obtained.

"Effect of the invention" According to the present invention, 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.

■ Since the driving force is applied between the middle and front of the reed when pressing and releasing keys, the point of application of the force is close to that during performance, making it suitable for performances by pianists ■ Movable yoke and keys Since these are integrated, the movement of the key can be controlled not only when the key is pressed but also when the key is released, expanding the control range and improving control accuracy. As a result, it is possible to reproduce the H7 key and improve the performance of consecutive hits.

■ Compared to the conventional impact method, the thrust characteristic against the moving stroke is 7 lats. Therefore, reproducibility is particularly improved in the low-speed drive range (during soft tone reproduction, pianissimo performance).

- Since the key is always controlled according to the supplied current regardless of the position of the key, controllability is extremely improved when performing 7-point feedback control.

■ By inserting a permanent magnet into the magnetic circuit and time-divisionally extracting the coil output voltage as it traverses the magnetic field, it can also be used as a key speed detection sensor.

■ Since it provides driving force in the middle and front of the reed, it can be applied to a wide range of pianos and is extremely versatile. This is because the pitch of the key arrangement in the above part is internationally standardized. By the way, the versatility of the system shown in Figure 8 was low.

[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. 1(B) is a sectional view taken along line A-A in the above figure. In addition, FIG. 1(C) is a sectional view showing a modification of the movable yoke in the first embodiment, and FIG.
2 is a cross-sectional view showing another modification of the movable yoke, FIG. FIG. 3 shows a second embodiment of the present invention, FIG. 3 (A) is a side view of the main part of the key drive device, FIG. The figure is an explanatory diagram showing the key thrust characteristics of the second embodiment. FIG. 5 is an explanatory diagram showing the speed at which the hammer is operated by the key drive device shown in the first and second embodiments. Figure 6 is the second one above! I! This figure shows an example of actually incorporating the key drive device shown in the example into a keyboard instrument. Figure (A) is an exploded perspective view, Figure (B) is a side view of the main part, and Figure (C) is the same figure. It is a sectional view taken along line CC of figure (b). FIG. 7 is a sectional view showing an example of actually incorporating the key driving device shown in the first embodiment into a keyboard instrument. FIG. 8 is a sectional view of a conventional key drive device for an automatic keyboard instrument. l... Coil 2... Fixed yoke 3... Movable yoke 73... White key 74... Black key 80...・Inside the reed 82...In front of the reed 84...Shelf board S...Hollow part

Claims (1)

[Scope of claims] 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, the external a coil that generates a magnetic field according to an energizing current from the key; a movable yoke fixed to the lower surface of the key and having a hollow portion opening at the lower end; fixed to the coil at a position close to and opposite to the movable yoke; A key drive device for an automatic keyboard instrument, comprising: a fixed yoke formed in a shape whose relative amount of opposing area with the movable yoke changes along the swinging direction of the key.