JP2672372B2 - Music box pickup device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a music box pickup device, and more precisely converts the ringing vibration of a music box into an electric signal.

[Prior Art] A conventional music box sounding mechanism, as shown in FIG.
When the pin 2 formed as a protrusion on the outer circumference of the cylinder bounces the tip of the valve 3, the vibration of the valve is transmitted to the pedestal 4 of the music box, and the resonance plate 5 is further vibrated and converted into sound. .

The above-mentioned sounding sound of the music box has a tone color peculiar to the music box and has been used as various sound sources and is popular, but there is a defect depending on its use.

 The main three drawbacks are the following three points.

The volume cannot be adjusted according to the external environment.

 The size of the resonance plate cannot be reduced.

(Because the volume becomes low) The life of the music box is short.

(Approximately 6,000 times of playing) Regarding the contents of the above-mentioned drawbacks, regarding the volume adjustment such as quiet place and noisy place where the music box is installed, daytime and nighttime, difference in volume sense between people, etc. Although there is a request, the conventional music box could only voluntarily make a constant sound and could not arbitrarily adjust the volume.

Regarding the above, there is a demand that the entire music box be downsized depending on the application, but there is a drawback that the resonance plate portion cannot be made small. The reason is that in order to efficiently convert vibration into sound and to secure a sound volume above a certain level, a resonance plate area for converting into air vibration is required to some extent.

However, there is a drawback in that the life of the music box is not sufficient in the applications that are frequently used. The breaking of the music box is the main factor that determines the life of the music box. There is a problem that the valve breaks due to material fatigue, because the valve is used near the stress limit of the material in order to make the sound of the music box as loud as possible. Generally, the music box life compensation is a valve failure rate of 6.5% at the acceptable quality level (AQL) when driven continuously for 25 hours.
It is about. Converting the above 25 hours into the number of playing sounds will be about 6,000. For example, when it is used for a watch, if it sounds once per hour, it will be 8760 times a year, and the 6,000 times will have a life of about 8 months, which is the minimum life of a watch.
I am not satisfied with my six years.

As mentioned above, the conventional music box has some drawbacks depending on its application, so in order to remedy the drawbacks, a method of extracting the vibration of the music box as an electric signal and amplifying the speaker as in other electric musical instrument pickups is used. Has been devised. According to this method, the above drawbacks can be almost solved.

The drawback of is that the volume can be freely changed by changing the amplification rate, and the drawback of is that it can be miniaturized by replacing the resonance plate with a speaker, and the drawback of is that the amount of valve deflection and the maximum stress can be reduced. Can be solved by As a result, the volume decreases, but it can be covered by changing the amplification factor.

[Problems to be solved by the invention]

As described above, by adding an electric pickup device to the music box, the drawbacks of the conventional music box can be improved, but various problems have occurred to faithfully pick up the music box sound.

A piezoelectric element is generally used as the pickup element, but the method of using the piezoelectric element is generally that the piezoelectric element is directly attached to the vibrating body and the strain stress due to vibration is taken out as an electric signal.

When this method is applied to a music box, one example is
As shown in the figure. The piezoelectric element 6 is bonded to one surface of the pedestal 4 of the music box, and the vibration of the pedestal 4 is detected as an electric signal. However, the detection by this method cannot faithfully reproduce the music box sound, and the sound quality is on the high temperature side. On the other hand, the popping noise of the valve was emphasized, and the resonance on the low temperature side tended to disappear. I could only hear it as a so-called bad sound and did not reach the practical level.

This is because the music box has a unique vibration mode, and since the vibration is not picked up, a reproduced sound faithful to the original sound cannot be obtained.

When the vibration state is examined, as shown in FIG. 7, the vibration path is transmitted from the epicenter of the valve 3 to the pedestal 4, and the vibration reaches the piezoelectric element 6 to be converted into an electric signal. . The vibrations that affect the piezoelectric element 6 are longitudinal waves 21 and transverse waves 22 that propagate in the pedestal 4, and surface acoustic waves 23 that are generated on the pedestal surface due to the influence of both waves. The three waves and their reflected waves are detected by the piezoelectric element, but other than that, there is vibration of the pedestal that is not detected by the piezoelectric element in this method.

Next, regarding the vibration that is not detected by the piezoelectric element,
This will be described with reference to the drawings. The figure shows a state that is equivalent to the vibration of a music box. It shows a state in which a vibrating body 7a having mass m (equivalent to a valve) is supported by a support body 7b having mass M (equivalent to a pedestal) at the tip of the leaf spring 7.

If the mass M is infinitely larger than the mass m, the displacement (swing) of the support 7b indicated by the arrow 8b due to the vibration of the vibrating body 7a indicated by the arrow 8a does not occur.
There is no generation of sound waves due to the displacement of the resonance plate 5 in contact with. (Some sound waves are generated due to the three-wave vibration shown in FIG. 7) The actual music box adjusts the mass M, and the vibration of the vibrating body 7a causes appropriate displacement (rocking) of the support body 7b. Then, the resonance plate is vibrated to generate a sound wave. The influence of the support 7b is that when the mass M is selected to be a relatively large value, the sound volume is small but the sound generation time is long, whereas when the mass M is selected to be a relatively small value, the sound volume is large but the sound generation time is shortened. It is necessary to select an appropriate mass M.

As described above, the displacement (swing) vibration of the support 7b has a great influence on the sound of the music box, and this displacement vibration must be detected to reproduce a faithful music box sound.

For example, looking at the case where the piezoelectric element is directly attached to the support 7b as shown in FIG. 9, the support 7b and the piezoelectric element 6 are integrally displaced, so that the strain stress due to the displacement indicated by the arrow 8b is applied to the piezoelectric element. Is not generated, there is no output, and displacement vibration of the support 7b cannot be detected. Needless to say, this example is the sixth
It is equivalent to the example shown in the figure, and the displacement vibration is not detected in the structure in which the piezoelectric element is attached to the pedestal.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a pickup device capable of detecting a displacement vibration of a pedestal of a music box to obtain a reproduced sound faithful to an original sound.

[Means for solving the problem]

In order to achieve the above object, the present invention supports a pedestal of a music box on a substrate through a vibration isolation mechanism, installs a piezoelectric element for pickup on the substrate side, and transmits a vibration transmitting member between the pedestal and the piezoelectric element. Alternatively, it is characterized in that the displacement vibration of the pedestal can be picked up by connecting with a vibration transmission part having a projection shape provided on the pedestal side.

[Action]

FIG. 10 is a diagram showing the operation principle of the vibration pickup portion of the present invention, in which the support 7b is supported on the substrate 8 by the support spring 9 so that the displacement vibration indicated by the arrow 8b of the support 7b is the substrate. The displacement amount of the substrate 8 is made sufficiently smaller than the displacement amount of the support 7b so that it is not transmitted to the 8 side, and the difference in the displacement amount between the two is converted into strain stress of the piezoelectric element and detected as an electric signal. .

As for the structure for generating strain stress in the piezoelectric element 6, only the outer periphery of the plate-shaped piezoelectric element (round or rectangular) is fixed to the substrate 8, and the central portion is supported so that it can freely bend and vibrate vertically. Together with the center of the piezoelectric element, the vibration transmission member 10
The piezoelectric element 6 can detect the displacement vibration of the support 7b.

FIG. 11 is a view for explaining the vibration isolation mechanism of the pedestal, which is a component of the present invention, in which the support 7b corresponding to the pedestal is vibration-proofed on the substrate 8.

In the figure, K is a restoration coefficient and c is a viscous damping coefficient.

Here, the amplitude F of displacement vibration of the support 7b and the substrate 8 during vibration
If the ratio τ = f / F with the amplitude f of the force transmitted to Is represented by

Where ω: circular frequency It is.

 The above relationship is as shown in FIG.

In the range, τ <1, and if ω / ω _c is further increased, that is, if the stiffness K of the support spring is reduced, the transmissivity τ is reduced as much as possible, and the vibration damping effect of the substrate can be improved. However, in reality, if the spring is too weak,
Since the amount of displacement of the support 7b due to external impact increases,
It is necessary to select an appropriate value, and vibration leakage to the substrate must be somewhat suppressed. On the other hand, the effect of viscous resistance is In the range of, since τ is increased rather, it is against the purpose of preventing the transmission of vibration. However, in order to suppress the continuation of free vibration due to accidental impact, it is better to give appropriate damping.

By vibrating and supporting the support 7b as described above,
The displacement vibration of the substrate can be made smaller than the displacement vibration of the support 7b. Therefore, if the difference in the amount of displacement between the two is detected, the displacement of the support 7b can be relatively detected.

〔Example〕

As shown in FIG. 1, the central portion of the lower surface of the pedestal 4 of the music box is fixed on the substrate 8 via the vibration-proof support portion 11,
A gap is formed between the lower surface of the substrate and the upper surface of the substrate 8. With the above structure, the pedestal 4 can move up and down like a seesaw on the substrate 8 with the anti-vibration support portion 11 as the center. A part of one end of the lower surface of the pedestal is attached to the vibration transmission member 10
Is coupled to the piezoelectric element 6 fixed to the substrate side via, and the coupling portion is pressed (pressed) by a spring 12 provided at the other end of the pedestal. When the pin 2 provided on the cylinder 1 flips the valve 3, the piezoelectric element 6 can pick up the ringing vibration of the music box including the displacement vibration of the pedestal.

The above is the outline of the entire structure. To explain the detailed structure, FIG. 2 shows an embodiment of the vibration-proof support portion, and the base 4 and the substrate 8 are provided with a rubber bush 13 and a screw 14 between them. This is a joint between the two, and it has both a spring effect due to the elasticity of the rubber and a damping effect due to the internal loss of the rubber for vibration isolation support. The rubber hardness should be soft and sponge rubber is enough. As a supporting method other than rubber, there is a method of supporting with a leaf spring or a coil spring, but it is difficult to restrict the movement of the supported pedestal to a movement only in a specific direction, and there is a vibration directly transmitted inside the spring material. Since it has a drawback that it is transmitted to the substrate and is combined with the vibration transmitted from the vibration transmission member 10 to the piezoelectric element 6 to change the sound quality, it seems to be difficult for actual use.

Next, the structure of the piezoelectric element part will be described. As shown in FIG. 3, the thin metal plate 15 has the same thin piezoelectric element 6 bonded to one side thereof, and electrodes 18 are formed on both sides of the piezoelectric element to form an electrical signal. The output terminal of. The metal plate 15 has a circular or rectangular shape with a thickness of 0.1 to 0.3 mm and a diameter of about 30 mm or less. The diameter of the piezoelectric element 6 is smaller than the diameter of the metal plate, the metal plate portion outside the piezoelectric element is welded or adhered to the substrate, and the central portion is configured so that it can freely flexurally vibrate. A vibration transmission member 10 is arranged at the center of the piezoelectric element,
The piezoelectric element and the pedestal are coupled to each other, and the vibration of the pedestal is transmitted to the piezoelectric element. When the vibration transmission member 10 is made of rubber, a relatively good sound quality can be obtained. Since rubber has a poor high-frequency vibration transmissibility, high-frequency noise due to the flipping of the valve is cut, and sound quality with less noise is obtained. The shape of the vibration transmitting member may be a comparatively thin cylindrical shape as shown in FIG. 3, but when rubber is used for the vibration transmitting member, the area on the piezoelectric element side is made conical as shown in FIG. The sound quality can be improved by widening it and slightly increasing the damping rate of the vibration of the piezoelectric element. Both contact surfaces of the vibration transmitting member are adhered to each other or a pressure is applied so that the contact does not separate during vibration. In the case of this embodiment shown in FIG. 4, the piezoelectric element side is bonded and the pedestal side is pressure-welded.

Regarding the installation position of the vibration transmission member with respect to the piezoelectric element, the lowest temperature can be detected when it is in the center of the piezoelectric element, and it moves to the higher temperature side as it shifts in the outer peripheral direction, so it is necessary to select an appropriate position according to your preference. There is. On the other hand, on the pedestal side, the vibration immediately below the position where the valve is screwed to the pedestal causes vibration that is relatively faithful to the original sound, so it is preferable to dispose the vibration transmission member at that position.

Further, instead of the vibration transmitting member, a protrusion-shaped vibration transmitting portion is provided on the pedestal side, and the tip of the vibration transmitting member is pressed against the piezoelectric element, or displacement vibration can be picked up.

Returning to FIG. 1, the other points will be described. The adjusting screw 16 adjusts the pressure applied to the vibration transmitting member 10. Further, the protrusion 17 regulates the displacement of the pedestal due to an external impact, and normally faces the pedestal with a slight gap maintained. Further, the material of the substrate 8 is preferably one having a large mass such as metal, and it is better to make it larger than the weight of the music box.

FIG. 13 shows the fatigue curve of the material used for the valve in this example, where the horizontal axis is the number of repetitions and the vertical axis is the maximum stress. The material is hot-worked Ni-Cr-Mo steel.

In this figure, for example, the maximum stress
When the 78kg f / mm ² lower the 62.4kg f / mm ² to 20% of stress, the number of repetitions will be extended 10 times little. Reducing the stress means that the amount of bending of the valve is reduced, and the volume energy is also reduced by that amount in proportion to the square of the rate of decrease of the stress. However, as in the present invention, the vibration of the valve is picked up by the piezoelectric element. If so, it can be amplified by the amplifier, which will eventually extend the life of the valve.

〔The invention's effect〕

As is clear from the above description, according to the present invention, the displacement vibration of the pedestal of the music box can be detected, so that it is possible to pick up an electric signal faithful to the original sound. as a result,
A music box sound can be emitted from a speaker by amplifying the electric signal, which has not been put into practical use in the past due to the above sound quality problem, but when the present invention can be put into practical use, its by-product effect The following features have also appeared.

 You can now adjust the volume of the music box.

Since the resonance plate can be replaced with a speaker, miniaturization is possible.

It has become possible to extend the valve life of the music box several times or more.

As described above, according to the present invention, the range of use has expanded to fields that could not be used with conventional music boxes.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention, FIG. 2 is a sectional view of the vibration-proof support portion shown in FIG. 1, FIGS. 3 and 4 are side views of a piezoelectric element portion, and FIG. FIG. 6 is a side view showing a conventional music box, FIG. 6 is a side view showing an example in which a piezoelectric element is applied to the conventional music box, FIG. 7 is an explanatory view showing a vibration transmission path, and FIG. 8 shows a vibration state of the conventional music box. Equivalent explanatory diagram,
FIG. 9 is an explanatory view showing an example in which a piezoelectric element is applied in FIG. 8, FIG. 10 is an explanatory view of the principle of the present invention, FIG. 11 is an explanatory view of the vibration isolation principle, and FIG. FIG. 13 is a graph showing the vibration damping characteristics, and FIG. 13 is a graph showing the fatigue curve of the material. 1 ... Cylinder, 2 ... Pin, 3 ... Valve, 4 ... Pedestal, 6 ... Piezoelectric element, 8 ... Substrate, 10 ... Vibration transmitting member, 11 ... Vibration support, 12 ... Spring , 13 …… rubber bush, 14 …… screw, 15 …… metal plate, 16 …… adjustment screw, 17 …… protrusion, 18 …… electrode.

Claims (1)

(57) [Claims] 1. A pick-up device for a music box in which a singing vibration of a music box is converted into an electric signal by a piezoelectric element through a pedestal that transmits vibrations. In the pick-up device, the pedestal of the music box is supported on a substrate in a vibration-proof manner, and the pedestal and the substrate side. The music box pickup device is characterized in that the piezoelectric elements installed in the above are connected by a vibration transmitting member or a projecting vibration transmitting portion provided on the pedestal side so that displacement vibration of the pedestal can be picked up.