JPH032955Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to an actuator for an automatic piano performance device that automatically performs keystrokes based on stored information of piano performance.

(Conventional device) An automatic piano performance device equipped with playback and recording functions consists of an actuator (solenoid unit) that automatically drives the keys using electrical signals during playback, and a key sensor unit that is used during recording. The arrangement relationship is shown in Fig. 1.

In FIG. 1, 1 is a key forming a piano keyboard, 2 is an actuator disposed below the rear end of the key, and 3 is a key sensor unit disposed below the front end of the key. This key sensor unit 3 is used to obtain information regarding the movement of the key 1 (key presses, keystroke speed). Calculate from dimensions.

The actuator 2 includes, for example, a solenoid coil 1 wound around a bobbin 10 as shown in FIG.
1 is placed between the upper common yoke 12 and the lower common yoke 13, and a truncated conical fixed yoke 14 is placed in the hollow part thereof, and its large diameter end is fixed to the upper common yoke 12. A movable element (plunger) 15 having a concave portion that fits into the fixed yoke 14 is arranged opposite to the fixed yoke 14, and a thrusting shaft 16 is fixed to this movable element 15, and this is connected to the central axis of the fixed yoke 14. The actuator head is inserted into a through hole, and a rubber cap (actuator head) 17 is attached to the protruding end of the actuator head.
The fixed yoke 1 is fixed by applying the required voltage to the coil 11.
4 is magnetized, and the movable element 15 is attracted to it to generate an upward thrust. In other words, the key 1 is pushed up by the thrust.

In this case, the excitation control of the coil 11 is performed by an electrical signal generated by a control unit (computer, etc.) based on information regarding the movement of the keys, so the keys act as if the player had pressed them with his or her fingers. It will be a similar movement.

However, in the actuator having the above structure, when obtaining a large thrust force, the number of turns of the solenoid coil increases and the DC resistance increases, resulting in increased power consumption, generation of a large amount of heat, and a large temperature rise. In particular, when a large number of keys are activated, such as in a duet performance, the actuator also operates in response, causing the area around the actuator to become overheated, which may have an adverse effect on the piano body. Furthermore, since the part that slidably supports the movable part such as the plunger is made of metal, there is a problem in that noise is generated due to relatively large friction during operation.

(Purpose of the invention) The purpose of the invention is to provide an actuator for an automatic piano performance device that has a high heat dissipation effect, suppresses overheating, and can reduce noise.

(Summary of the invention) In this invention, a solenoid coil wound around a bobbin is arranged between an upper common yoke and a lower common yoke, and a plunger yoke is arranged inside the bobbin so as to be movable in the axial direction. An actuator head is attached to the tip, and the solenoid coil is energized based on information about the movement of the keys on the piano keyboard to generate a thrust that moves the plunger yoke upward, and this thrust pushes the keys up and releases the fingers. In an actuator for an automatic piano performance device that automatically performs the same operation as a keystroke, a pair of cylindrical plate yokes with a gap in the middle are arranged coaxially with the bobbin, and the contact surface with the plunger yoke is It is insert-molded to form a bobbin material, which quickly dissipates the heat generated by the coil and allows the plunger yoke to move with low noise.

(Example) Figure 3 shows an example of this invention.
1 is an upper common yoke, 22 is a lower common yoke, 2
3 is a solenoid coil, and this coil 23 is wound around a bobbin 24 and placed between the upper common yoke 21 and the lower common yoke 22. Reference numeral 25 designates a plunger yoke, and an actuator head 26 is attached to a thrusting shaft at the tip thereof, and the plunger yoke 25 is supported by a spring or the like so as to bring it into contact with the lower surface of a key of a piano keyboard.

27 is a plate yoke formed into a cylindrical shape as shown in FIG. 4, with a gap (slit) 27A in the middle.
have. The plate yokes 27 are insert-molded so that a pair of plate yokes 27 are arranged coaxially with the bobbin at both ends of the bobbin 24 when the bobbin 24 is molded, and the contact surface 25A with the plunger yoke 25 is made of bobbin material.

With the above structure, when the solenoid coil 21 is excited, a thrust force is generated to move the plunger yoke 25 upward, and the plunger yoke 25 rises. As the plunger yoke 25 rises, the key is pushed up, and the key is driven as if the key were pressed by a finger.

In this case, the plunger yoke 25 is connected to the bobbin 24.
It slides upward while in contact with the inner contact surface 24A, resulting in low-noise operation due to reduced friction. Furthermore, the heat generated by the coil 23 is quickly released to the outside via the insert-molded plate yoke 27, and the temperature rise of the coil 23 is suppressed.

Note that the same method can be applied to a collision type plunger. In that case, the fixed yoke penetrating portion becomes loosely fitted, resulting in less processing accuracy and lower noise.

(Effects of the invention) As described above, according to this invention, a cylindrical plate yoke with a gap in the middle is arranged coaxially with the bobbin, and the contact surface with the plunger yoke is insert-molded with the bobbin material. Therefore, the plate yoke is located close to the coil, and the heat generated by the coil is quickly released to the outside via the plate yoke. That is, the heat dissipation effect is enhanced and the temperature rise can be suppressed, so that even when a large number of actuators operate at the same time, such as during a duet performance, overheating around the actuators is prevented, and there is no risk of adverse effects on the piano body. In addition, since the sliding surface of the plunger yoke is made of bobbin material,
It is possible to reduce noise caused by friction, prevent the generation of noise during automatic piano performance, and improve the performance effect.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the arrangement relationship of the actuator and key sensor unit constituting the drive unit of the automatic piano performance device with respect to the keys;
The figure is a sectional view showing an example of the structure of a conventional actuator, and FIG. 3 is a sectional view showing an example of this invention.
FIG. 4 is a perspective view of the plate yoke in the same embodiment. 1...Key, 3...Key sensor unit, 21
...Upper common yoke, 22...Lower common yoke,
23...Solenoid coil, 24...Bobbin, 2
4A...Contact surface, 25...Plunger yoke, 2
6...Actuator head, 27...Plate yoke, 27A...Gap.

Claims (1)

[Scope of utility model registration request] A solenoid coil wound around a bobbin is arranged between an upper common yoke and a lower common yoke, and a plunger yoke is arranged inside the bobbin so as to be movable in the axial direction, and an actuator head is attached to the tip of the plunger yoke. The solenoid coil is energized based on information regarding the movement of keys on a piano keyboard to generate a thrust that moves the plunger yoke upward, and this thrust pushes up the key to automatically perform an action similar to pressing a key with a finger. In an actuator for an automatic piano performance device, a pair of cylindrical plate yokes with a gap in the middle are arranged coaxially with the bobbin, and insert molding is performed so that the contact surface with the plunger yoke is made of bobbin material. An actuator for an automatic piano performance device characterized by: