JPH0325794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an actuator for a player piano that can be made into a unit and built into a keyboard section.

[Prior art and its problems] In general, the actuator installed in a player piano and driving the keys includes an excitation coil and a movable actuator that is slidably inserted through the excitation coil with a small gap in the center. A well-known electromagnetic plunger is used, which includes an iron core and a yoke that houses an excitation coil and forms a magnetic path.

Then, by driving this electromagnetic plunger with an electric signal obtained by reproducing information recorded in advance on a tape, etc., the key is operated as if it were pressed by hand. ing.

Figure 1 shows the conventional mounting structure of this type of actuator.
A mounting plate 3 extending long along the direction in which the mounting plates are arranged in parallel (direction of arrow A) is arranged substantially vertically. On this mounting plate 3, a plurality of electromagnetic plungers 5 corresponding to each key 2 are arranged in two stages, upper and lower, and are movable and adjustable in the direction in which the keys 2 are arranged side by side.

Therefore, on the back surface of the mounting plate 3, a total of four sliding grooves 4 in the shape of a square are formed in parallel at predetermined intervals in the vertical direction.

Each electromagnetic plunger 5 has a yoke 6 formed in a substantially square shape from a metal plate such as soft iron, and the upper and lower ends of this yoke 6 are slidably connected to a set screw 7 and the sliding groove 4. It is positioned and fixed by a square nut 8 which is inserted and screwed onto the set screw 7.

An excitation coil 10 is provided in the internal space 9 of the yoke 6.
is housed together with the movable iron core 11. This movable iron core 11 projects above and below the yoke 6, and the projecting end that projects upward further passes through an insertion hole 12, which is a square hole or the like, drilled in the shelf board 1, and is provided at the top of the insertion hole 12. The push-up button 13 is placed close to and opposed to the lower surface of the rear end of the corresponding key 2.

The upper electromagnetic plunger 5 and the lower electromagnetic plunger 5 are vertically arranged in a staggered manner and are offset by the pitch of the key 2.

A specific example of the structure of such a conventional electromagnetic plunger is disclosed in Japanese Patent Publication No. 48-33689. In this electromagnetic plunger, the upper end of the fixed yoke is convex, and the felt disc 2
2 is separated from the coil 35 by a large distance.

By the way, in general, the distance between the shelf board and the keys on a piano is extremely small (typically about 28 millimeters), and actuators for player pianos must quickly drive the keys, which are quite heavy. Therefore, the actuator for a player piano must be made thin without reducing the number of windings.

However, in general, when the actuator is made thinner, the number of windings thereof is reduced, resulting in a problem in that the driving ability of the key is reduced.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a strong and thin actuator for a player piano.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned points, and includes a yoke structure that is interposed between a shelf board and a key at a position on the rear side of the reed from the inside of the reed. In the actuator for a player piano, the electromagnetic plunger has an excitation coil supported on the yoke structure, and a concave portion connected to the excitation coil on the key side. , a fixed yoke each having a convex portion on the shelf side; a shaft slidably penetrating the fixed yoke and capable of protruding toward the key; fixed to the end of the shaft on the shelf side; a movable yoke having a concave portion configured with a surface that can fit with the convex portion of the fixed yoke; This is an actuator for a player piano, which has an uplift button housed in a recess.

[Operation] In the actuator for a player piano according to the present invention, when the excitation coil is energized, the yoke component is magnetized, and a magnetic flux is generated that passes through the magnetic gap between the fixed yoke and the movable yoke. When the movable yoke is attracted to the fixed yoke, a part of the movable yoke can be overlapped with a part of the fixed yoke in the height direction of the excitation coil. As a result,
The proportion occupied by the movable yoke in the narrow space between the shelf board and the key can be reduced. Therefore, without reducing the number of turns of the excitation coil,
The actuator can be made thinner.

Further, since the key side of the fixed yoke is made into a recess, when the movable yoke is separated from the fixed yoke, the push-up button can be stored in the recessed part of the fixed yoke on the key side. Therefore, the excitation coil can be made thinner by a distance corresponding to the thickness of the raised button without reducing the number of turns of the excitation coil.

Furthermore, in the actuator for a player piano according to the present invention, since the fixed yoke has a convex shape on the shelf board side, while ensuring sufficient wall thickness, the distance between the movable yoke and the recessed part, that is, the magnetic gap, can be reduced. This makes it possible to further reduce the thickness of the actuator while ensuring movable yoke driving thrust.

[Example] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 2 is a sectional side view of a main part of a keyboard section equipped with an actuator according to the present invention, and FIG. 3 is an exploded perspective view of the actuator.

In these figures, on the upper surface of the shelf board 1 is a keyboard reed 20 consisting of a reed front 21, a reed middle 22, a reed back 23, etc.
is placed, and on top of it are multiple keys 2.
is arranged so as to be swingable in the vertical direction using its intermediate portion as a rotational fulcrum.

That is, the key 2 is swingably supported by the balance key pin 24 implanted on the reed center 22 being inserted into a through hole 25 formed in the middle portion thereof and having a substantially fan-shaped cross section in the vertical direction. It is something that

Further, a well-known action mechanism (not shown) is placed on the rear end portion 2A of the key 2 via a capstan 26, so that the front end portion 2B is normally
1, and the rear end portion 2A is placed on the rear reed 23 with a felt 27 interposed therebetween.

Further, an oval key pin 28 is planted on the upper surface of the front reed 21. This oval key pin 2
The upper end of the key 2 is always engaged in a recess (not shown) formed on the lower surface of the front end 2B of the key 2, thereby regulating and preventing the key 2 from rotating in the left-right direction.

A flat actuator 30 is disposed in a space 15 between the shelf board 1 and the key 2 and between the middle 22 and rear 23 of the reed.

This actuator 30 includes a pair of upper and lower yoke structures 31 that extend long along the direction in which the keys 2 are arranged side by side.
A, 31B, and the pair of upper and lower yoke components 3
1A and 31B, a plurality of electromagnetic plungers 32 are arranged in a staggered manner corresponding to each key 2.

The pair of upper and lower yoke components 31A and 31B are formed of a magnetic material such as soft iron, and thereby provide a common magnetic path to each electromagnetic plunger 32. On the upper surface of the lower yoke structure 31B formed in a substantially square shape, the yoke structure 31B
An upper yoke component 31A formed in a plate shape is disposed so as to cover the opening of the set screw 33.
It is fixed by.

The upper end of the rear wall of the yoke structure 31B is bent rearward, so that the yoke structure 3
The mounting portion 34 is formed integrally with the mounting portion 1B. This mounting portion 34 is the upper yoke component 31A.
It is also fixed to the front end of the upper surface of the rear reed 23.

Further, the front end side of the yoke structure 31B is fixedly held by a shield case 36 that shields the printed circuit board 35.

In this way, the yoke structure 31B is arranged above the shelf board 1 at a predetermined distance.

The rear end of the printed circuit board 35 is fixed to the lower surface of the front end of the yoke structure 31B via an insulating paper (not shown). Said shield case 3
Reference numeral 6 is formed of a thin perforated plate and has a substantially square shape, and its upper surface is mounted and fixed on the front end upper surface of the upper yoke structure 31A, and its lower surface is mounted and fixed on the upper surface of the shelf board 1, respectively.

A plurality of insertion holes 37 and 38 are arranged and bored in a staggered manner in the bottom surfaces of the upper yoke structure 31A and the lower yoke structure 31B, respectively, corresponding to the electromagnetic plungers 32.

Each electromagnetic plunger 32 is formed into a cylindrical shape as a whole, and includes a bobbin 39 that integrally has flanges at both upper and lower ends, an excitation coil 40 wound around the outer peripheral surface of the bobbin 39, and an upper and lower part inserted into the bobbin 39. A pair of yokes 41 and 42 and a lower yoke 4
The shafts 43 and the like are fitted and fixed in the inner holes of the two.

To explain the details further, each flange of the bobbin 39 is fixed to the lower surface of the upper yoke structure 31A and the inner bottom surface of the lower yoke structure 31B with double-sided tape 44, respectively. The lead wire 45 of the excitation coil 40 is inserted into a lead wire insertion hole (not shown) drilled in the upper yoke component 31A.
After being led out through the shield case 3
6 and connected to the terminal portion of the printed circuit board 35. The upper yoke 41 is formed into a substantially cylindrical shape and is fitted and fixed to the upper end opening of the bobbin 39, and its upper end is fitted into the insertion hole 37 of the upper yoke structure 31A.

The lower end of the yoke 41 is formed into a truncated conical shape, and a recess 46 is formed in the upper surface of the yoke 41 to accommodate the protruding button 13 screwed onto the upper end of the shaft 43.

On the other hand, the lower yoke 42 is formed in a cylindrical shape, and its upper end is slidably inserted into the inner hole of the bobbin 39 through the insertion hole 38 bored in the lower yoke component 31B. A collar 47 is integrally fixed to the portion.

The upper end side opening of this yoke 42 forms a tapered hole 48 so as to be able to fit into the lower end of the upper yoke 41.

The shaft 43 is formed into a rod-shaped body made of non-magnetic material, and its lower end is connected to the lower yoke 42.
The upper end of the upper yoke 41 slidably passes through the inner hole of the upper yoke 41 and projects above the upper yoke structure 31A.

Therefore, the lower yoke 42, collar 47, and shaft 43 are integrally coupled to form a movable member that is attracted upward and operates when a signal current is supplied to the excitation coil 40, as will be described later. ing.

A guard member 5 such as felt is provided on the upper surface of the collar 47.
0 is placed thereon, and the flange 47 is placed on a guard member 51 which is normally formed into a belt shape of felt or the like on the upper surface of the shelf board 1.

A heat pipe 52 is further housed inside the lower yoke structure 31B. This heat pipe 52 is for diffusing the heat of the excitation coil 40 in the direction in which the keys 2 are arranged side by side.
It extends in the longitudinal direction of 1B. Further, a resin material 53 having high thermal conductivity is filled between the heat pipe 52 and each electromagnetic plunger 32. As the resin material 53, epoxy resin mixed with metal powder, filler, etc. is used.

In addition, in FIG. 3, 54 is a guide bush that is fitted and fixed in the inner hole of the yoke 41, 55 and 56 are wood screws and spacers that fix the pair of upper and lower yoke components 31A and 31B, and 57 is a side opening of the yoke component 31B. It is a side cap that closes off the area.

In the actuator 30 having such a configuration, the electromagnetic plunger 32 corresponding to a certain key 2
When a signal current is supplied to the excitation coil 40, the lower yoke 42 is attracted and raised by the action of the magnetic flux generated in the magnetic gap between the upper and lower yokes 41 and 42, so that the shaft 43 rises together with the lower yoke 42, causing the key to open. The push-up button 13 pushes up the lower surface of the rear end portion 2A of 2.

Therefore, the key 2 is driven as if it were pressed by hand.

When the signal current to the excitation coil 40 disappears, it is demagnetized, so the shaft 43 and the lower yoke 42 fall due to their own weight and return to the initial position shown in FIG. 2, and the key 2 also returns accordingly. do.

Thus, according to this actuator 30, since it is disposed between the shelf board 1 and the key 2,
There is no need to process the shelf board 1 at all, and a decrease in the strength of the shelf board 1 can be prevented.

Further, a plurality of electromagnetic plungers 32 corresponding to each key 2 are connected to a pair of upper and lower yoke structures 31A, 31B.
Since they are commonly housed within the unit and made into a unit, they can be put together compactly, and installation and adjustment work to the keyboard section is easy.

Further, since the actuator 30 is not visible from the outside of the piano body, deterioration of the appearance of the piano itself can be prevented.

Furthermore, since the pair of yoke components 31A and 31B provide a common magnetic path to each electromagnetic plunger 32, they reduce magnetic resistance and at the same time, together with the heat pipe 52, heat generated in the electromagnetic plunger 32 is released from its entire length. In order to dissipate heat, the temperature distribution due to the heat generated by the actuator 30 is made uniform. Therefore, the driving force of the electromagnetic plungers 32, which are frequently used, does not decrease due to the influence of heat, and the driving force of each plunger 32 can be kept constant.

FIG. 4 is a side sectional view showing a modification of the above embodiment.

The difference from the above embodiment is that the heat pipe is removed, and a well-known coil spring ring 80 is installed between the uplift button 13 and the yoke 41 to improve the rise of the movable members including the yoke 42, shaft 43, etc. The point lies in the intervention of

Since the other configurations are substantially the same as those of the above embodiment, the same reference numerals are given and the explanation thereof will be omitted. In the figure, 81 is the insulating paper mentioned above. It is clear that the same effects as in the above embodiment can be obtained with this configuration as well.

[Effects of the Invention] As described above, the actuator for a player piano according to the present invention allows the actuator to be made thinner without reducing the number of turns of the excitation coil.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a main part showing the mounting structure of an actuator in a conventional player piano, FIG. 2 is a side sectional view showing a main part of a keyboard section equipped with an actuator according to an embodiment of the present invention, and FIG. 4 is an exploded perspective view of the actuator, and FIG. 4 is a side sectional view of the keyboard section showing another embodiment. 1...Shelf board, 2...Key, 15...Space, 30...
... Actuator, 31A, 31B ... Yoke component, 32 ... Electromagnetic plunger, 39 ... Bobbin, 40 ... Excitation coil, 41, 42 ... Yoke, 43 ... Shaft, 52 ... Heat pipe.

Claims (1)

[Scope of Claims] 1. An actuator for a player piano having an electromagnetic plunger interposed between a shelf board and a key at a position on the rear side of the reed from the inside of the reed and supported by the shelf board via a yoke structure. , the electromagnetic plunger includes an excitation coil supported by the yoke structure,
a fixed yoke connected to the excitation coil and having a concave portion on the key side and a convex portion on the shelf side; a shaft that slidably passes through the fixed yoke and can protrude toward the key; a movable yoke fixed to an end on the shelf side of the shaft and having a recess configured with a surface that can fit with a convex part of the fixed yoke; An actuator for a player piano, characterized in that it has a raised button that is housed in the recess when the actuator moves away from the fixed yoke.