JPH0432874Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a piezoelectric sound generator, such as a piezoelectric buzzer used in electronic equipment, and a piezoelectric sound generator used for tuning musical instruments.

(Prior Art) Conventional piezoelectric sound generators include, for example, the one shown in FIG. 5 (Japanese Utility Model Publication No. 56-55753), or the one shown in FIGS. ) etc. are known.

In the case of the former, as shown in FIG. The diaphragm 3 includes a piezoelectric element 5 that causes the diaphragm 3 to vibrate, and the diaphragm 3 has a lead terminal 7 extending from its outer peripheral edge.
has a substantially rectangular shape and is attached to the diaphragm 3 with its longitudinal direction substantially perpendicular to the lead terminals 7.

Therefore, in this piezoelectric buzzer (sound generator), the method of fixing the diaphragm 3 is the outer periphery fixing method, and the shape of the piezoelectric element 5 is approximately rectangular, so that the vibration mode of the diaphragm 3 In a piezoelectric buzzer whose diaphragm is asymmetrical with respect to its center, the piezoelectric element 5 is attached to the diaphragm 3 so that the lead terminal 7 is located at the position where the vibration displacement of the diaphragm 3 is least. It is designed to produce a large volume. Note that 9 is a resonance chamber.

Moreover, the latter shows a unimorph type piezoelectric sounding body.

In this unimorph type piezoelectric sounding body, a piezoelectric element 13 is attached to a substantially central portion of a diaphragm 11. Therefore, when an alternating voltage of a predetermined frequency is applied to the piezoelectric element 13, the diaphragm 11 resonates and a sound of a predetermined pitch is produced.

(Problems to be Solved by the Invention) However, such conventional piezoelectric sound generators have the following problems. In other words, in the former case, although it is possible to obtain the desired quality Q that approximates natural sound in the resonance curve, the piezoelectric sound generator itself becomes larger because the Helmholtz resonator is defined around the diaphragm. There was a problem that the problem occurred. On the other hand, in the case of the latter, although the piezoelectric buzzer itself becomes thinner, the value of the quality factor Q decreases and its frequency characteristics become flat as a whole, making the sound artificial and unpleasant to the auditory sense. There was also the problem that the volume was low.

(Means for Solving the Problems) Therefore, the present invention provides a plate-shaped support in which a recess is formed that opens in the thickness direction, and a membrane stretched over the support to cover the recess. a piezoelectric body, a piezoelectric body fixed to the membrane body, a plurality of switches arranged on the support body, and a control system installed in the recess and applying signals of frequencies corresponding to these switches to the piezoelectric body. It is an object of the present invention to solve the above problems by providing a piezoelectric sound generator characterized by comprising a circuit.

(Functions and Effects) In the piezoelectric sound generator according to the present invention, a recess is formed in the plate-shaped support and a membrane is stretched to cover the recess, so that the thickness of the piezoelectric sound generator itself is reduced by the support. It is determined by the thickness of the body and can be extremely thin overall. When the player selects and operates one of the plurality of switches, a signal having a frequency corresponding to that switch is applied from the control circuit to the piezoelectric body. Then, the membrane receives the vibration of the piezoelectric body and resonates due to membrane vibration, so unnecessary harmonic components are removed. Therefore, a sound with a natural tone from which unnecessary harmonic components have been removed is emitted from the membrane body. Even when emitting sounds of other frequencies, it is possible to obtain similarly natural tones. In this way, the performer can freely play notes of various pitches with natural tones. Moreover, the number of parts of the piezoelectric sound generator is reduced, and it can be manufactured at low cost.

That is, according to the present invention, by operating the switch, the performer can play tones of various pitches with natural tones. Further, since the piezoelectric sound generator according to the present invention is small and has excellent portability, it has the advantage that a performer can perform anywhere. That is, the present invention can provide a musical instrument with excellent portability.

Furthermore, the piezoelectric body causes the membrane body to vibrate, causing the membrane body to resonate. Therefore, even if the piezoelectric body vibrates including unnecessary harmonic components, the harmonic components are attenuated. Unwanted harmonic components are often emitted as harsh sounds. Since such harmonic components are attenuated, high-quality sound with natural tone can be obtained. By the way, in order to reduce such harmonic components and output high-quality sound, it is usually necessary to add an electric filter, tone control circuit, etc. to the output terminal of the control circuit. Since the piezoelectric sound generator according to the present invention does not require such an electric filter, the overall shape of the piezoelectric sound generator can be reduced in size, and
Another advantage is that costs can be reduced.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 to 3 show an embodiment of a piezoelectric sound generator according to the present invention.

In these figures, 21 is a rectangular thin (3 mm
The support body 21 is a plate-shaped support body, and a circular opening (concave portion) 23 is formed approximately in the center of the support body 21 . This opening 23 is formed through the support body 21 in the thickness direction of the support body 21.
Membranes 25 and 27, which are thinner than the support 21 and are made of a flexible material such as plastic film or paper, are attached to the upper and lower surfaces of the support body 21. Therefore, the opening 23 is connected to these membrane bodies 2.
5 and 27.

As the material for this support body 21, a material such as cardboard or styrofoam is used that has a predetermined hardness and rigidity and is as light as possible.

A thin disc-shaped piezoelectric element 31 is adhered to the inner surface of the central portion of one of the membrane bodies 25 and 27. That is, this piezoelectric element 31 causes the membrane body 2 to
Nos. 5 and 27 induce membranous vibration.

On the other hand, in the support body 21 in FIG. 1, a circular small opening 33 is formed adjacent to the opening 23, and inside this small opening 33 is a control circuit 35 for the piezoelectric element 31 and a battery 37 that is its power source. is accommodated. Further, this control circuit 35
It is connected to the piezoelectric element 31 by a lead wire 41 via a groove 39 formed in the piezoelectric element 31 . This lead wire 41
The width of the groove 39 in which the groove 39 is disposed is made as narrow as possible. This is to clarify the nodes of membrane vibration caused by the membrane bodies 25 and 27. And 5
Reference numeral 1 denotes a switch, which is fixed at one corner of the support body 21. In addition, this switch 51 is connected to the lead wire 5.
3 is connected to a control circuit 35 (board).

FIG. 3 shows the configuration of the control circuit 35. According to this figure, a gate circuit 57 that is opened and closed by a switch 51 is interposed between the sawtooth wave forming circuit 55 and the piezoelectric element 31.
By closing the gate circuit 57, the gate circuit 57 is opened.

Next, the effect will be explained.

In this embodiment, when the switch 51 is turned ON, the gate circuit 57 opens and passes the sawtooth wave signal formed in the sawtooth wave forming circuit 55, and outputs the sawtooth wave signal to the piezoelectric element 31. do. As a result, the piezoelectric element 31 vibrates at a predetermined frequency, causing the membrane bodies 25 and 27 to vibrate. This membranous vibration produces sound at a predetermined pitch. In this case, the degree of goodness Q of the resonance curve of this membranous vibration increases, and it is possible to obtain sound pronunciation that approximates natural sounds.

Further, as described above, since the membrane bodies 25 and 27 are stretched over both sides of the piezoelectric element 31, the area of the radiation surface of the generated sound is increased, and the sound volume can also be increased. Furthermore, this piezoelectric sound generator can be formed thin as a whole, making it extremely convenient to carry, and moreover, it can be manufactured at low cost due to the reduction in the number of parts.

FIG. 4 shows another embodiment of the invention.

In this embodiment, as shown in FIG.
A plurality of switches 61 are arranged in parallel on the support 21 in the shape of, for example, a keyboard. A divider circuit 65 is connected to the pulse generator 63. Furthermore, when any of these switches 61 is closed, the sawtooth wave forming circuit 67 outputs the sawtooth wave to the single piezoelectric element 31 in response to the corresponding pulse.

Therefore, in this embodiment, a single piezoelectric sound generator can produce sounds at a plurality of pitches. Further, in this case, by appropriately changing the diameter of the opening 23, its resonance characteristics can be changed; for example, the diameter is set corresponding to a predetermined sound range (one octave).

Note that this piezoelectric sound generator can also be used for tuning, and because the main body has become thinner, it has become possible to sell it not only for orchestral performances but also in combination with textbooks and the like. in this case,
The piezoelectric sound generator shall be set to produce a reference pitch tone.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view showing an embodiment of a piezoelectric sound generator according to the present invention, Fig. 2 is a longitudinal sectional view of the piezoelectric sound generator according to an embodiment, and Fig. 3 is a longitudinal sectional view of the piezoelectric sound generator according to an embodiment. Circuit diagram showing the control circuit of the piezoelectric sound generator, No. 4
FIG. 5 is a circuit diagram showing a control circuit of a piezoelectric sound generator according to another embodiment of the present invention, FIG. 5 is a vertical cross-sectional view of a conventional piezoelectric sound generator, and FIG. 6 is another conventional piezoelectric sound generator. 7 is a schematic perspective view showing the conventional piezoelectric sound generator, and FIG. 7 is a side view showing the conventional piezoelectric sound generator. 21...Support, 23...Opening (recess), 27
... Membrane body, 31 ... Piezoelectric element (piezoelectric body).

Claims (1)

[Scope of Claim for Utility Model Registration] A plate-shaped support in which a recess is formed that opens in the thickness direction, a membrane stretched over the support so as to cover the recess, and fixed to the membrane. a piezoelectric body, a plurality of switches disposed on the support body, and a control circuit disposed inside the recess for applying signals of frequencies corresponding to these switches to the piezoelectric body. Features a piezoelectric sound generator.