JPH041697A - Key driving device for automatic keyboard musical instrument - Google Patents

Abstract

PURPOSE:To comparatively smooth thrust force-stroke characteristic for a key by providing a fixed yoke whose upper part is formed in sawtooth shape, and a movable yoke whose lower part is formed so as to be engaged with play with the sawtooth shape part of the fixed yoke. CONSTITUTION:A magnetic field in a direction along the fluctuating direction of the key 1 is generated by permitting a current to flaw on a coil 5, and a magnetic attractive force is generated between the fixed yoke being formed as a pair of two yokes and the movable yoke 6, which controls key depression and key separation. In such a case, since the magnitude of the attractive force for the movable yoke 6 is decided by a current value to energize the coil 5, a driving force for the key 1 can be easily and surely controlled by adjusting the current value. Also, an almost constant attractive force can be applied to the key 1 in spite of the elevating position of the key 1 by engaging with play the sawtooth parts 4a, 6a formed on both the fixed yoke 4 and the movable yoke 6 with each other, and the thrust force-stroke characteristic for the key 1 becomes flat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a key drive device for an automatic keyboard instrument, and more particularly to a key drive device that controls keystrokes and key releases using magnetic force.

"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.

Such key drive devices generally use a bush type solenoid, and devices using a pull type solenoid are also known. The visitor presses the key by pushing up the rear end of the key using a button-shaped solenoid installed on the top of the shelf, located at the back of the balance bin that rotatably supports the key. In addition, in the latter, a sliding plunger is pulled down by a pull-type solenoid located in front of the balance bin, and the key is pressed by pulling down the tip of the key connected to the plunger. This is how it was done.

"Problem to be Solved by the Invention" By the way, in a key drive device using a bush type solenoid, the rear end of the key is pushed up, so a holding member is needed to prevent the key from lifting up. Not only is this necessary, but the point of application of the force is significantly different from when the pianist actually performs, making it difficult to reproduce the performance faithfully.

On the other hand, with a key drive device that uses a pull type solenoid, it is possible to avoid the generation of operating noise that would be detrimental to the performance when the plunger slides, and the plunger is generally quite heavy. There is also a problem that the sliding resistance is also large, which adversely affects the keychain.

In addition, if the plunger is fixed to the back of the key, the plunger will become unstable as the key rotates, so in order to prevent this, the structure that connects the plunger to the key must be complicated. I don't get it. Moreover, the dimensions of the solenoids are generally larger than the width of the key, so it is difficult to arrange these solenoids in a horizontal row.
They have to be arranged in two levels, one above the other, which requires a lot of effort to assemble and inspect during mounting, making it difficult to ensure accuracy, and each key has a different touch.

SUMMARY OF THE INVENTION 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 in conventional key drive devices.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is provided with a plurality of devices disposed on the upper surface of the shelf of an automatic keyboard instrument below each weight and closer to the player than the key rotation support. , a coil that generates a magnetic field in the direction along the rocking direction of the key in response to an externally applied current; fixed yokes are arranged along the same axis and have serrated portions on their upper portions; and fixed yokes are attached to the back surface of the key in close opposition to two adjacent fixed yokes, and their lower portions are provided with serrated portions on the fixed yokes. It is characterized by comprising a movable yoke having a serrated portion that loosely fits into the movable yoke.

"Operation" In the key drive device of the present invention, when a current is passed through the coil, a magnetic field is generated in the direction along the swinging direction of the key, and the magnetic field is generated between the fixed yoke and the movable yoke, which are a set of two. A magnetic loop is formed between the fixed yokes and the movable yokes, thereby generating a magnetic attraction force between the pair of fixed yokes and the movable yokes to control keystrokes and key releases. In this case, since the magnitude of the attractive force applied to the movable yoke is determined by the value of the current flowing through the coil, the driving force applied to the key can be easily and reliably controlled by adjusting the current value. In addition, because the serrated portions formed on both the fixed yoke and the movable yoke loosely fit into each other, a nearly constant suction force acts on the key regardless of the key's ascending or descending position, and the thrust force against the key - the stroke The characteristics become flat.

"Example" Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a schematic configuration of the key drive device of this embodiment, and FIG. 2 is a front view, in which reference numeral 1 indicates keys of a player piano, and 2 indicates a reed to which keys 1 are attached. This is a shelf board that supports the inside.

On the upper surface of the shelf board 2, there is a spacer located on the front side (on the player's side) of a balance bin (not shown) installed in a reed that rotatably supports the keys 1, and arranged in the direction in which the keys 1 are arranged. A long base plate 3 is attached to the base plate 3. This base plate 3 is made of a soft magnetic material such as an iron plate.
A large number of plate-shaped fixed yokes 4 are connected to the mounting holes 3 formed in the base plate 3 with convex portions 4b formed at the bottom thereof. By being fitted into the base plate 3
The keys 1 are arranged in an upright state and arranged at equal intervals in the direction in which the keys 1 are arranged.

Two of these fixed yokes 4 form a set, and each set of fixed yokes 4.4 is located below each weight 1. A coil 5 is attached to one side (the left side in FIG. 2) of each set of fixed yokes 4.4. Further, on the back surface of each weight 1, a movable yoke 6 having a U-shaped cross section is attached to closely oppose each set of fixed yokes 4, 4.

The upper part of the fixed yoke 4 and the lower part of the movable yoke 6 are provided with sawtooth shapes that loosely fit into each other in a non-contact state.
J and 6 J are formed, respectively.

In the key drive device configured as described above, when the coil 5 is energized, a magnetic field is generated along the central axis of the coil 5, that is, the swinging direction (up and down direction) of the key 1, and the fixed yoke 4.4, base plate 3, movable yoke 6
A magnetic loop as shown by the arrow in FIG. 2 is formed between the two. A magnetic attraction force is generated between the fixed yoke 4.4 and the movable yoke 6, and this causes the key 1 to be moved along with the movable yoke 6 to the fixed yokes 4, 4 side (downward).
The person is drawn to the key and presses the key. Further, by adjusting the current flowing through the coil 5 when the key is released, the speed at which the fixed yokes 4, 4 and the movable yoke 6 are separated, that is, the key release speed can be controlled.

In this case, the magnitude of the attractive force on the movable yoke 6 is determined by the current value flowing through the fill 5, so by adjusting the current value! The driving force for l can be easily and reliably controlled.

Furthermore, in this case, the magnitude of the suction force acting on the key 1 will vary somewhat depending on the vertical position of the key 1 (that is, the magnitude of the distance between the fixed yoke 4 and the movable yoke 6).
In the above device, both yokes 4 and 61 are formed with serrated portions 4m and 6a that fit loosely into each other.Therefore, a nearly constant suction force is maintained regardless of the vertical position of the fal.
It is possible to make it work. In other words,
The thrust-stroke characteristics of the keys IJ become flat, and as a result, performance reproducibility in low-speed drive ranges such as when playing soft tones or pianissimo playing can be improved.

According to the key drive device described above, each weight 1 is pulled downward I in front of the balance bottle to perform a keystroke, so that the point of application of force during automatic performance is almost the same as when the player actually plays. This makes it possible to perform more faithful reproduction than a conventional key drive device using a bush type solenoid.

Furthermore, according to this key drive device, unlike key drive devices using conventional pull-type solenoids, there is no operating noise or sliding resistance. Therefore, the key touch during automatic performance does not differ greatly from that during actual performance. In the case of this embodiment, the thickness of the movable yoke 6 is 2 am@
In that case, the weight of the movable yoke will be approximately 14 grams, but the static load (down weight) at the start of keystroke on a general piano is approximately 60 grams, and the weight of the movable yoke is approximately 14 grams. Not only is this addition to the key 1 not a practical problem at all, but by attaching the movable yoke 6, it is possible to reduce the balance weight that was conventionally required to be attached to the key 1.

Furthermore, in this key drive device, since the direction of the magnetic field generated by each coil 5 is along the swing direction of the key l,
It has the advantage that there is little magnetic interference or negative influence on other adjacent sets of fixed yokes 4. It is composed of only four types of parts, and the other three types except the coil 5 are all sheet metal parts such as iron plates, so it is possible to reduce the parts cost and it can fit within the width dimension of the key. In addition, it is extremely easy to assemble, making it possible to fully automate the assembly process and inspection process.Furthermore, the base plate 3 and each fixed yoke 4 are designed to prevent heat generation from the fill 5. Since it acts as a heat sink and radiation fin to dissipate heat to the outside, it naturally has excellent heat radiation efficiency without the need for special heat radiation measures.

The first embodiment has been described above, and next, the second embodiment will be described with reference to FIGS. 3 to 6.

The key drive device of this second embodiment has almost the same structure as the key drive device of the first embodiment except that the shape of the movable yoke is different, so the same components are denoted by the same reference numerals. A detailed explanation will be omitted.

In this embodiment, a flat plate member is processed into a corrugated shape so that the lower part has a serrated portion 10! A movable yoke 10 is used, and this movable yoke 10 is located above each set of fixed yokes 4, 4 and attached to the back surface of the key 1.

The width of the movable yoke 10 is slightly smaller than the width of the key 1 and slightly larger than the mutual spacing between the fixed yokes 4.4 of each set.

The key drive device of this second embodiment in which such a movable yoke 10 is adopted not only has the same effect as the first embodiment, but also can achieve further weight reduction and miniaturization. , and has excellent magnetic properties that allow sufficient driving force to be obtained.

In other words, since the movable yoke 10 is processed into a corrugated shape, the magnetic path length (dimension along the longitudinal direction of the key 1) of the movable yoke 10 is substantially sufficiently larger than that when the movable yoke 10 is shaped like a flat plate. Even if the thickness of the yoke 10 is made sufficiently thin, a large magnetic path cross-sectional area can be secured, and the path length of the magnetic loop formed between the fixed yoke 4.4 and the movable yoke 10 of each set is shown in FIG. As shown in FIG. 2, it is sufficiently smaller than in the case of the first embodiment, so that a sufficient driving force for the key 1 can be ensured.

And regarding the area corresponding to the fixed yoke 4.4,
In the case of the first embodiment, sufficient length was required to ensure the thickness of the movable yoke.

However, in the movable yoke 10 according to the second embodiment, by setting the width sufficiently wide, it is possible to secure a corresponding area with a margin, and the thickness of the movable yoke 10 can be set to 0.
It is possible to make it sufficiently thin, about 8 to 1 mm, and its weight can be reduced (for example, about 8 grams) compared to the first embodiment, and the effect on key touch is accordingly further reduced. can be reduced.

Moreover, the width dimension of the movable yoke 10 is different from that of the fixed yoke 4 of each set.
．． Since the distance between the fixed yokes 4 and 4 is slightly larger than that of the fixed yokes 4 and 4, even if the position of the fixed yoke 4.4 is slightly shifted to the left and right with respect to the movable yoke 10 during mounting, there is no problem with the formation of the magnetic loop, and therefore the assembly is easy. Work becomes easier and reliability increases.

In order to commonly apply the key drive device of each of the above embodiments to various types of general pianos, it is necessary to have an installation space in which the external dimensions of the key drive device for one key are common to various pianos;
That is, the length of the front part of the balance bin is approximately 70 mm.
, a height of approximately 30 mm, and a radius of 1213 mm. However, in each of the above embodiments, the size is small enough to fit within such a space while ensuring sufficient thrust characteristics and magnetic shielding from adjacent coils. can be easily realized.

"Effects of the Invention" As explained in detail above, the present invention provides the following effects.

■Since each weight is pulled down in front of the balance pin and the key is pressed, the point of force application during automatic performance is almost the same as during actual performance, and the key drive using a conventional butshu type renoid is possible. It is possible to perform performance reproduction with more fidelity than with other devices.

■There is no operating noise or sliding resistance that occurs with conventional key drive devices using pull-type solenoids, and the movable yoke can be made sufficiently lightweight, so the key touch during automatic performance is as accurate as the actual key touch. There is no difference in performance.

■Because the serrated parts formed on both the fixed yoke and the movable yoke loosely fit into each other, a nearly constant suction force acts on the key regardless of the key's ascending or descending position, resulting in a thrust-stroke characteristic for the key. becomes relatively smooth.

- Since the direction of the magnetic field generated by each coil is along the swinging direction of the key, there is little magnetic interference or negative effect on other adjacent sets of fixed yokes.

■The structure is simple, reducing parts costs, making it small enough to fit in the width of the key, and being extremely easy to assemble, allowing full automation of the assembly and inspection processes. It is possible to achieve this.

■The fixed yoke acts as a heat sink to dissipate heat from the coil to the outside, so no special heat dissipation measures are required.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of a key drive device according to the present invention, with FIG. 1 being a perspective view and FIG. 2 being a front view. 3 to 6 show a second embodiment of the key drive device according to the present invention, in which FIG. 3 is a perspective view, FIG. 4 is a front view,
FIG. 5 is a plan view, and FIG. 6 is a side view. 0...Movable yoke, 0a... Serrated portion.

Claims (1)

[Scope of Claims] The keys are arranged on the upper surface of the shelf of the automatic keyboard instrument below each key and closer to the player than the key rotation support part, and the keys swing in response to an externally applied current. a coil that generates a magnetic field in a direction along the direction; and a coil arranged at the center of the windings of the coil and between the coils so that they are arranged along the direction in which the keys are arranged, and the upper part thereof has a serrated part. a movable yoke that is attached to the back surface of the key in close opposition to two adjacent fixed yokes, and whose lower part has a serrated portion that loosely fits into the serrated portion of the fixed yoke; A key drive device for an automatic keyboard instrument, comprising: