JPH06200976A - Silencer for piano sound - Google Patents

Abstract

PURPOSE:To dissolve propagation of vibration sound from the leg part of a piano to a floor by arranging an actuator displacing by an electric signal on the propagation course of vibration sound from the leg part of the piano to the floor, and dissolving the propagating vibration sound of the piano leg part with displacement of the actuator. CONSTITUTION:In a ground piano and the like, casters 12 are fitted to the lower ends of piano leg parts, and acceleration sensors 14 are fitted in proximity to the lower ends. Further an actuator 18 is arranged between the caster 12 and a floor F. The propagating sound vibration data of the piano leg part 10 detected by means of the acceleration sensor 14 is input to an opposite phase electric power generating device 16. The vibration of opposite phase against the detected vibration data is output from the opposite phase electric power generating device 16 to the acuator 18. Hereby the sound vibration of the piano leg part 10 is dissolved by the sound vibration of the actuator 18, and hence propagation of the sound vibration to the floor is dissolved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound muffling device for piano sounds, and more particularly to a sound muffling device for preventing sounds generated during piano performance from propagating from the piano legs to the floor.

[0002]

2. Description of the Related Art When playing a piano placed on the floor above the floor of an apartment house, the sound produced is (1) airborne and (2) airborne. There is a case where the sound vibrates the wall and propagates through the wall, and (3) there is a case where it propagates from the piano legs to the floor, that is, the ceiling below the floor. Has become one of the causes.

In particular, the sound propagated from the piano leg to the floor makes a great contribution to noise. Conventionally, in order to reduce such sound propagation as much as possible, the leg is placed on an elastic sheet such as rubber. Has been taken, but it has little effect. Not only the piano sound is 27-4200H
There is no elastic body that has a sound range of z or higher, and can mute sound over the entire range.

[0004]

SUMMARY OF THE INVENTION A piano sound muffling apparatus according to the present invention comprises an actuator which is arranged at least at one position of a piano sound propagation path from the piano leg to the floor and which is displaced by an electric signal, and a piano leg. And means for applying an electric signal to the actuator so as to cancel the propagating sound vibration and the displacement of the actuator. (Claim 1) The piano is in contact with the floor surface by casters, but the mounting position of the casters differs depending on the type of piano. That is,
In the grand piano, casters are attached to the tips of the three elongated legs. On the other hand, in the upright piano, casters are attached to the joints provided at the four corners of the bottom surface of the main body. In the present invention, for the upright piano, this joint is referred to as a leg. In any kind of piano,
The actuator may be interposed between the caster and the floor (claim 2), or may be interposed between the leg and the caster (claim 3). Further, it is necessary to provide at least one actuator, but it is preferable to provide each actuator for each leg in order to obtain a higher sound deadening effect.

The propagating vibration in the leg portion can be separately detected by an acceleration sensor provided in the leg portion or the caster, and an electric vibration signal of opposite phase can be given to the actuator based on the propagating sound vibration data. As a result, the sound vibrations cancel each other out, and the propagation to the floor can be almost eliminated. (Claim 4) Instead of this, the fact that a force is applied to the actuator by the sound vibration of the piano leg and a counter electromotive force is generated is utilized to generate an electric signal for canceling the counter electromotive force. By giving the actuator, it is possible to control without an acceleration sensor (claim 5). This is to control the voltage applied to the actuator so that it is always 0 V or constant, which is equivalent to infinite feedback and is useful because damping can be applied to all frequencies.

Alternatively, a supporting leg separate from the piano leg is provided below the piano body, and the piano body is supported by the supporting leg. The supporting leg is displaced by an electric signal. An actuator is attached to the piano leg or caster, and an acceleration sensor for detecting propagation sound vibration in the piano leg is provided. Based on the detected propagation sound vibration in the piano leg, an anti-phase vibration signal is output to the actuator. May be provided so that the propagating sound vibration in the piano leg and the displacement of the actuator cancel each other out. (Claim 6) In the same manner as in the above, in a piano having separate support legs, an actuator that is displaced by an electric signal is attached to the support legs, and counter electromotive force generated in the actuator is generated by propagating sound vibration in the piano legs. Means may be provided for applying an electrical signal to the actuator to cause it to cancel out the propagating sound vibrations in the piano leg and the displacement of the actuator. (Claim 7) Examples of the actuator that is displaced by an electric signal include a piezo element, a magnetostrictive element, and an electromagnetic element, and the piezo element is preferable in terms of load resistance and frequency characteristics. (Claim 8)

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a case where the device of the present invention is applied to a grand piano. A caster 12 is attached to the lower end of the piano leg 10, and an acceleration sensor 14 is attached to the side surface near the lower end. Between the caster 12 and the floor surface F,
An actuator 18 is arranged. Actuator 1
8 may be simply placed between the caster 12 and the floor surface F, or may be attached to the caster 12 by some means (not shown). The propagated sound vibration data in the piano leg 10 is detected by the sensor 14, and the antiphase power generator 1
6 is input. This device 16 gives a vibration of opposite phase to the actuator 18 based on the vibration data. As a result, sound vibrations cancel each other out, and the propagation of sound to the floor surface can be eliminated.

FIG. 2 shows a case where the device of the present invention is applied to an upright piano. The caster 12 is attached to each corner of the main body 11 via a flat leg portion (joint portion) 13. The acceleration sensor 14 is attached to the side surface of the support side plate 12 for the wheels of the caster 12. Other points are
This is the same as in the case of FIG. In the case of FIG. 1 as well, the sensor may be provided on the supporting side plate.

FIG. 3 shows a leg 1 of a grand piano.
When the actuator 18 is attached between 0 and the caster 12, FIG. 4 shows the same case in the upright piano.

FIG. 5 shows a case where the back electromotive force of the actuator 18 is used without using the acceleration sensor 14. A force is applied to the actuator by the vibration sound propagating in the piano leg, and a counter electromotive force is generated. The counter electromotive force is input to the counter electromotive force canceling signal generator 17. This device 17 provides an electrical signal to the actuator 18 that counteracts the back electromotive force. Although FIG. 5 shows the upright piano, a similar configuration may be used for the grand piano. Further, the counter electromotive force cancellation signal generator 17 may be used also when the actuator is arranged between the leg portion and the caster.

In the embodiment shown in FIG. 6, the piano body 11
The support leg 17 is provided separately from the original leg portion having the casters 12. The support leg is longer than the piano leg portion (including casters), and the support leg supports the piano so that the piano leg portion floats inside. The support leg 17 is in the shape of a casing, and an actuator 18 is provided inside the support leg 17 with a little space above. The actuator 18 is supported in the leg portion 17 by using a spring member (not shown), and the expansion / contraction operation of the actuator 18 acts on the floor F via the protrusion 19. In the illustrated example, the supporting legs are applied to an upright piano, but the present invention is not limited to this, and may be applied to a grand piano. In that case, the support leg 1
7 has a long shape, and an actuator 18 is arranged at an appropriate position inside, and its operation is similar to that of the protrusion 19
Is transmitted to the floor F via. In the illustrated case, the actuator 18 is housed inside the casing-shaped leg portion 17, but instead of this, the actuator 18 is arranged between the support leg 17 and the piano body 11 or at the lower end of the support leg 17. May be. In the case shown in the figure, the acceleration sensor 14 is attached to the caster, the propagation sound vibration in the caster is detected, and the antiphase vibration signal is applied to the actuator 18 by the antiphase power generator (not shown). Instead of this,
Without providing the acceleration sensor 14, the actuator 18 may be provided with an electric signal for canceling the counter electromotive force generated in the actuator 18 by the propagating sound vibration in the support leg.

In the embodiment of FIGS. 1 to 6, the acceleration sensor 14 may be attached to the bottom portion, the lower portion, or other places of the piano body.

Table 1 shows the results of evaluating the loudness of the sound on the first floor by installing a piano on the flooring floor of the second floor of an apartment house in the examples shown in FIGS.

Table 2 shows data as Comparative Examples 1 to 5 when the cancellation control was not performed in Examples 1 to 5.

[0015]

[Table 1]

[Table 2]

[0016]

EFFECTS OF THE INVENTION Without affecting the sound of the piano when playing it, it is possible to largely cancel the sound vibration that propagates to the floor from the legs of the piano, which is the main cause of piano noise. Help solve the noise problem of the.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment.

FIG. 2 is a schematic diagram showing a second embodiment.

FIG. 3 is a schematic diagram showing a third embodiment.

FIG. 4 is a schematic diagram showing a fourth embodiment.

FIG. 5 is a schematic view showing a fifth embodiment.

FIG. 6 is a schematic view showing a sixth embodiment.

[Explanation of symbols]

 10 …… Piano leg 11 …… Piano main body 12 …… Caster 13 …… Piano leg 14 …… Accelerometer 15 …… Caster support side plate 16 …… Anti-phase power generator 17 …… Counter electromotive force cancellation signal generation Device 18 …… Actuator F ………… Floor surface

Claims (8)

[Claims] 1. An actuator that is displaced by an electric signal disposed at at least one place in a propagation path of a piano sound from a piano leg portion to the floor, and a propagating sound vibration in the piano leg portion and a displacement of the actuator cancel each other out. And a means for applying an electric signal to the actuator to control the sound of the piano. 2. The actuator is arranged between a caster attached to a piano leg and a floor.
Piano sound muffling device described in. 3. The piano sound deadening device according to claim 1, wherein the actuator is arranged between a leg portion of the piano and a caster attached to the leg portion. 4. The piano leg or caster is provided with an acceleration sensor for detecting a propagating sound vibration in the piano leg, and the means for applying the electric signal detects the propagating sound vibration in the piano leg. 2. A vibration signal having an opposite phase is first given to the actuator.
The piano sound muffling device according to any one of 1 to 3. 5. The means for applying the electric signal provides the actuator with an electric signal for canceling a counter electromotive force generated in the actuator due to propagation sound vibration in a piano leg. The sound muffling device for piano according to any one of 1. 6. A support leg, which is separate from the piano leg portion, is provided below the piano body, and the piano leg is supported by the support leg. An actuator that is displaced by an electric signal is provided on the support leg. A means for attaching, to a piano leg or a caster, an acceleration sensor for detecting a propagating sound vibration in the piano leg, and applying a vibration signal of an opposite phase to the actuator based on the detected propagating sound vibration in the piano leg. A piano sound muffling apparatus having the above, whereby the propagating sound vibration in the piano leg and the displacement of the actuator cancel each other. 7. A support leg, which is separate from the piano leg portion, is provided below the piano body so as to support the piano body by the support leg, and an actuator that is displaced by an electric signal is provided on the support leg. There is a means for providing the actuator with an electric signal that cancels the counter electromotive force generated in the actuator due to the propagating sound vibration in the piano leg, and thereby the propagating sound vibration in the piano leg and the displacement of the actuator are provided. A piano sound muffling device that cancels each other. 8. The piano sound muffling device according to claim 1, wherein the actuator is a piezo element, an electrostrictive element, a magnetostrictive element, or an electromagnetic element.