JPH0325795B2 - - 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 built into a keyboard section by unitizing the actuator.

[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 of a metal plate such as soft iron into a substantially square shape, and the upper and lower ends of this yoke 6 are slidably engaged with a set screw 7 and the sliding groove 4. It is positioned and fixed by a square nut 8 that 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 29 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 closer to the front of the reed than in the middle of the reed. In the actuator for a player piano, the electromagnetic plunger is connected to an excitation coil supported by the yoke structure, and the end on the key side is connected to the excitation coil. A fixed yoke formed in a concave or convex shape, a movable yoke having an opposing surface that can be fitted with the key-side end of the fixed yoke, and a shaft suspended from the key for attaching the movable yoke to the key. and a plate-shaped armature fixed to the movable yoke and extending in a plane direction substantially perpendicular to the axis of the shaft.

[Function] In the actuator for a player piano according to the present invention, when the movable yoke is attracted to the fixed yoke by energizing the excitation coil, the electromagnetic plunger fixes a part of the movable yoke in the height direction of the excitation coil. It can be overlapped with a part of the yoke. 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, the actuator can be made thinner without reducing the number of turns of the excitation coil.

Further, the thin plate-like armature can reduce leakage of magnetic flux formed in the yoke component, and a strong and thin actuator can be obtained.

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

FIG. 2 is a partially cutaway side view of a keyboard section showing an embodiment of the present invention, and FIG. 3 is a side sectional view showing an enlarged actuator thereof.

In these figures, a keyboard reed consisting of a front reed 21, a middle reed 22, a rear reed (not shown), etc. is arranged on the top surface of the shelf board 1, and a plurality of keys 2 are arranged on top of the keyboard reed. is disposed so as to be swingable in the vertical direction using its longitudinal 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 formed in the middle portion thereof and having a substantially fan-shaped cross section in the vertical direction. It is something.

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 8 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 rotation of the key 2 in the left-right direction.

The actuator 30 operates in a space 60 between the shelf board 1 and the key 2 and between the front of the reed 21 and the middle of the reed 22.
It is housed and located in.

In this actuator 30, the upper end of the shaft 43 of each electromagnetic plunger 32 is engaged with the front end 2B of the key 2.

Therefore, the shaft 43 is inserted from above the key 2 into the insertion hole 61 bored in the front end 2B of the key 2 via the guide pipe 62, and is movable up and down.
Its upper end is locked to the upper surface of the key 2 by a nut 63 and a rotation stopper 64 to prevent it from coming off downward.

On the other hand, the lower end of the shaft 43 protruding downward from the key 2 is fitted and fixed into the inner hole of the upper yoke 42 of the pair of yokes 41 and 42 constituting the electromagnetic plunger 32. is slidably inserted into the inner hole of the

In this case, in the pair of yokes 41 and 42, the lower end of the yoke 41 is connected to the lower yoke structure 3.
It is fitted and fixed in the insertion hole 38 of 1B.

On the other hand, the yoke 42 is fixed to the lower surface of an armature 65 disposed above the yoke component 31A. Further, the yoke 42 is inserted into the bobbin 39 through the insertion hole 37 of the yoke component 31A to form a magnetic gap with the yoke 41.

Further, 40 is an excitation coil, which is wound around a bobbin 39 which is a cylindrical body made of soft iron or the like.

On the upper surface of the armature 65, a punching 66 formed in an annular shape from leather, felt, etc. is placed and fitted onto the shaft 43.

52 is a heat pipe for heat radiation, and 53 is housed in a space within the yoke components 31A and 31B. Further, this space is filled with a resin material 53 having high thermal conductivity. As this resin material 53, for example, epoxy resin mixed with metal powder, filler, etc. is used.

Note that the lower end of the shaft 43 corresponding to the key 2 disposed on the keyboard reed joist 67 passes through the yoke 41 and is inserted into a through hole 68 formed in the keyboard reed joist 67 .

70 is a guide bush through which the lower end of the shaft 43 is slidably inserted.

In the actuator 30 having such a configuration, when a driving current is supplied to the excitation coil 40 of the electromagnetic plunger 32 corresponding to a certain key 2, the movable members consisting of the yoke 42, the shaft 43, the armature 65, etc. It is attracted downward due to the magnetic flux generated in the magnetic gap between the two. That is, the actuator 30 drives the key 2 by lowering the movable member such as the shaft 43 as if it were pressed by hand.

Then, when the excitation coil 40 is demagnetized, the key 2 is rotated back to its original initial position by the load of the action mechanism, and the movable members such as the shaft 43 are pulled up.

Therefore, even in such a configuration, the key 2
can be driven smoothly.

In this case, since the upper end of the shaft 43 is engaged with the key 2 by a nut 63 or the like, the key 2 and the shaft 43 can be operated integrally.
In addition, since the distance between the key 2 and the actuator 30 can be adjusted by rotating the nut 63, variations in the driving force of the electromagnetic plunger 32 for each key 2 can be adjusted even after the actuator 30 is assembled.
This can be easily done from above.

Further, the actuator 30 is connected to the front end 2 of the key 2.
Since the key B is pulled in, there is no risk that the key 2 will come off the balance key pin 24 unlike in the push-up type.

In addition, in this embodiment, the keyboard reed center 67
Although the case where the actuator 30 is arranged is described above, the present invention is not limited to this, and the actuator 30 is fixed to the middle 22 of the reed or the front 21 of the reed, and
Of course, it is also possible to remove.

According to such an 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 in a unit and can be assembled compactly, attachment to the keyboard section and adjustment work are 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 for 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 absorbed from the entire length thereof. 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.

[Effects of the Invention] As explained above, in the actuator for a player piano according to the present invention, when the movable yoke is attracted to the fixed yoke, a part of the movable yoke overlaps a part of the fixed yoke in the height direction of the excitation coil. Therefore, it is possible to reduce the proportion of space occupied by the shelf board of the movable yoke and the key. Therefore, the actuator can be made thinner without reducing the number of turns of the excitation coil.

In addition, since the armature made of a thin plate is fixed to the movable yoke, it is possible to reduce the leakage of magnetic flux formed in the yoke structure when the excitation coil is energized, and it is possible to exert sufficient thrust for stable driving, resulting in a thinner design. Actuator can be obtained.

[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, and FIG. 2 is a partially cutaway side sectional view of a keyboard section equipped with an actuator according to an embodiment of the present invention. , FIG. 3 is an enlarged side sectional view of the actuator which is a part of FIG. 2. 1...shelf board, 2...key, 2B...front end of key,
24... Balance key pin (fulcrum), 30... Actuator, 31A, 31B... Yoke structure, 32... Electromagnetic plunger, 39... Bobbin,
40... Excitation coil, 41... Yoke (fixed yoke), 42... Yoke (movable yoke), 43... Shaft, 52... Heat pipe, 60... Space,
65... Armature.

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 closer to the front of the reed than in the middle 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 or convex end on the key side, and an end on the key side of the fixed yoke. a movable yoke having an opposing surface that can be fitted with the movable yoke; a shaft suspended from the key for attaching the movable yoke to the key; and a shaft fixed to the movable yoke and extending in a plane direction substantially perpendicular to the axis of the shaft. An actuator for a player piano, characterized by comprising a plate-shaped armature that is present in the actuator, and an actuator for a player piano.