JPS5929040B2 - piezoelectric vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a piezoelectric vibrator used as a drive source for a sounding body such as a piezoelectric speaker, and relates to a piezoelectric vibrator that is capable of reproducing bass frequencies and practical frequency ranges. .

A piezoelectric vibrator has the characteristics that it can be easily made thin in a piezoelectric speaker using the vibrator as a driving source, and consumes very little power.

In recent years, with the development of integrated circuits for generating synthetic speech, piezoelectric speakers have been attracting attention as a replacement for conventional dynamic speakers, especially due to their low power consumption characteristics.

However, piezoelectric speakers have a practical sound range and are difficult to reproduce low tones, making it difficult to put them into practical use, and they have only been put into practical use for high-pitched sounds.

Therefore, the present invention provides a piezoelectric vibrator that can be used as a drive source for a piezoelectric speaker aimed at reproducing a practical frequency range.

That is, in this invention, in a piezoelectric vibrator in which one end of a metal plate composed of a piezoelectric plate is fixed and the other end is a vibrating tip, the metal plate width (d) of the vibrating tip is equal to the fixed side metal plate width. This piezoelectric vibrator has a dimension ratio d/A' with respect to the effective length A) of 0.75 to 2.

The piezoelectric vibrator according to the present invention specifies the shape of a bimorph piezoelectric vibrator having a cantilever structure, and widens the reproduction frequency when configured as a sounding body.

To explain a conventional rectangular piezoelectric vibrator 1 as a piezoelectric vibrator having a cantilever structure, as shown in FIG. It is inserted and fixed into the fixing part 4 of the speaker case, and has a structure in which the other end is a vibrating tip, and the center point of the diaphragm 5 is connected to this vibrating tip to assemble it into a piezoelectric speaker.

In the drawing, the diaphragm 5 has its peripheral end fixed to a support part 7 of a speaker case via a support member 6 made of foamed polyurethane.

When measuring the acoustic output of this conventional piezoelectric speaker using the strip piezoelectric vibrator 1 as a driving source, the output is insufficient, especially in the low frequency range.

On the other hand, the piezoelectric vibrator 11 according to the present invention has a second
As shown in the figure, in order to make the width of one end of the rectangle narrower than the width of the opposite end, it is a quadrilateral that includes a right angle at one end from both adjacent sides of one end of the rectangle, and the rectangle is cut out. In other words, a piezoelectric plate 13 is bonded to the center of a table tennis racket-shaped metal plate 12 using adhesive or other means, and the narrow side of the metal plate 12 is inserted into, for example, a fixing part 14 of a speaker case and fixed. , the wider side of the metal plate 12 is the vibrating tip.

A piezoelectric speaker can be assembled by connecting the center point of a diaphragm 15 whose circumferential end is fixed to the supporting part 17 of the speaker case via a support member 16 made of foamed polyurethane to the vibrating tip of the piezoelectric vibrator 11. .

As described above, the piezoelectric speaker using the piezoelectric vibrator 11 according to the present invention, in which the width on the tip side of the vibrator is wider than that on the fixed side, has an improved low-frequency output when its acoustic output is measured, and is suitable for practical use. A flat frequency response can be obtained over a wide range.

The effect of the piezoelectric vibrator according to this invention, especially the improvement in the output sound pressure in the low frequency range of the speaker, is that in the case of a conventional rectangular vibrator, the low frequency output depends only on the bending vibration in the longitudinal direction of the vibrator. This is because, on the other hand, bending vibration in the width direction of the vibrator is utilized simultaneously with the length direction of the vibrator.

In other words, when the vibrator undergoes bending resonance, the acoustic output of the speaker increases, but in conventional rectangular vibrators, frequencies other than the first-order laminar resonance frequency f1 and the second-order laminar resonance frequency f2 in the length direction increase. Since there is no resonance point and the frequencies of fl and f2 are greatly different, the acoustic output between fl and f2 is reduced.

On the other hand, in the case of the piezoelectric vibrator of the present invention, there is a first-order laminar resonance frequency f'1 in the width direction of the vibrator between the above-mentioned first-order f1 and second-order bending resonance frequencies of 2 degrees. However, the acoustic output particularly in the bass range is improved, and a wide band of reproduced sound is achieved.

Therefore, the relationship between the effective length 1> of the vibrator according to the present invention and the width (d) of the vibrating tip of the vibrator is important, and the width (d) of the vibrating tip is divided by the effective length l). Dimension ratio d
By setting the value of ll in the range of 0.75 to 2, the first layer bending resonance frequency "nf'1 in the width direction described above can be changed to fl and f
2, which improves the acoustic output over the entire practical range width.

Next, regarding the shape of other parts of the piezoelectric vibrator according to the present invention, the width of the metal plate on the fixed side of the vibrator is arbitrary, and may be appropriately selected based on the size of the vibrating side, etc.

Furthermore, the shape of the rectangular cutout in the shape of the metal plate 12 is not specified and may be selected as appropriate.

For example, in addition to having the outer shape of the metal plate 12 formed by a straight line as shown in FIG. It is also preferable to set the connecting portion with the side diaphragm 15 (indicated by a black circle in Figure C) on the protruding metal plate 12.

On the other hand, the piezoelectric plate 13 is similar to the metal plate 12 shown in the drawings.
In addition to compounding on one side, it is also good to compound on both sides.
As shown in FIG. 3a, the piezoelectric plate 13 may be extended to the metal plate 12 within the fixed part 14 of the vibrator, and in this case, the primary laminar vibration force in the length direction increases. .

Alternatively, as shown in FIG. 3D, the width of the piezoelectric plate 13 may be expanded laterally to match the width of the metal plate 12 to increase the bending vibration force in the width direction.

Furthermore, when increasing the width of the piezoelectric plate 13 by O in the lateral force direction, a third
The piezoelectric plate 13 is equivalent to a circular piezoelectric plate 13 as shown in Fig. e, which increases the bending vibration force in the width direction and is easy to manufacture.

Up to now, the shape of the metal plate 12 has been explained using the above-mentioned rectangular notch as an example, but in this invention, the width of the vibration side of the vibrator 11 is substantially wider than that of the fixed side. Various shapes can be used, and for example, as shown in Fig. 3F, a substantially circular metal plate 12 may be used, in which a rectangle is aligned with one circumference of the circle, and a rectangular part that protrudes from the circle may be used. The fixed side is, for example, the circular piezoelectric plate 13 described above.
It is also good to combine them into a vibrator.

Next, an example according to the present invention will be shown to clarify its effects.

First, the conventional rectangular vibrator 1 shown in FIG. 1 has a length L6.
A metal plate 2 made of a phosphor bronze plate with a width of 8 mm and a thickness of 0.15 mm has a length of 10 m and 7 ft, a width of 8 mm, and a thickness of 0.1 mm.
A piezoelectric plate 3 made of a 5 mm zircon-lead titanate piezoelectric ceramic plate is glued to the fixed part of the vibrator 1.
The IL was adhesively fixed to the fixing part 4 of the speaker case, and fixed to the support part 7 of the speaker case via a support member 6 made of a foamed polyurethane sheet, with a thickness of 50 μm and a diameter of 3.
The center point of the diaphragm 5 made of a 0 mm polyimide film and the tip of the vibrator 1 were bonded with adhesive to complete a piezoelectric speaker.

On the other hand, the piezoelectric vibrator 11 according to the present invention shown in FIG. A piezoelectric plate 13 made of zircon-lead titanate piezoelectric ceramic having a length of 10 mr/L, a width of 8 m11 L, and a thickness of 0.15 m was bonded to form a piezoelectric vibrator.

Next, the same speaker case and diaphragm 15 as in the conventional example are used, and the fixed length of the metal plate 12 at the fixing part 14 is set to 3 mm, and the effective length of the vibrator is 13 mm as in the conventional example.
mm? With these settings, we created a piezoelectric speaker.

A sinusoidal voltage with an effective value of 1■ was applied to these two piezoelectric speakers, and the acoustic output at 10 CIr on the axis of the speakers was measured. FIG. 5 shows a case where a vibrator is used.

In the case of the conventional example, the frequency characteristic is the first-order layered resonance f1
is approximately 0.9 KHz, and the second layer resonance f2 is approximately 8 KHz.
It can be seen that there is no other resonance point, and the acoustic output between fl and f2 is greatly reduced.

On the other hand, in the case of the present invention, the first resonance f'1 in the width direction of the vibrator occurs between f and f2, which improves the low-frequency output in particular and makes it practical over a wide frequency range. It can be seen that sufficient output is obtained over the period.

Next, piezoelectric vibrators were manufactured using the same dimensions and materials as in the above-described embodiment of the present invention, but only the width of the vibrating tip of the metal plate 12 was varied, and changes in resonance frequency were measured.

The results are shown in the graph of FIG. 6, in which the horizontal axis represents the value of dll, which is the tip width (d) of the vibrator divided by the effective length, and the vertical axis represents the resonant frequency.

As is clear from the results, when the value of dll is in the range of 0.75 to 2, the first resonance f'1 in the width direction is effective between the first resonance f1 and the second resonance f2 in the length direction. It can be seen that it is located in

As detailed above, in the piezoelectric vibrator according to the present invention, the width of the vibrating tip side of the vibrator is made wider than the width of the fixed side, so that the reproduced sound obtained when assembled into a piezoelectric speaker is particularly The output in the bass range has been improved, showing excellent frequency characteristics.

[Brief explanation of the drawing]

1 is a side view and a bottom view of a conventional rectangular vibrator, FIG. 2 is a side view and a bottom view of a piezoelectric vibrator according to the present invention, and FIG. 3 is a bottom view showing another embodiment according to the present invention. FIG. 4 is a chart showing the relationship between frequency and acoustic output of a conventional speaker in an embodiment, FIG. 5 is a chart showing a relationship between frequency and acoustic output of a piezoelectric speaker according to the present invention, and FIG. It is a chart showing the relationship between child dll and resonance frequency. In the figure, 1...... rectangular vibrator, 2, 12...
・Metal plate, 3.13...Piezoelectric plate, 4,14...
... Fixed part, 5゜15 ... Vibration plate, 6,1
6...Support member, 7°17...Support portion, 11...Piezoelectric vibrator.

Claims (1)

[Claims] 1. In a piezoelectric vibrator in which one end of a metal plate composed of a piezoelectric plate is fixed and the other end is a vibrating tip, the metal plate width (d) of the vibrating tip is made wider than the width of the metal plate on the fixed side, and the size ratio dll to the effective length of the vibrator 12>
A piezoelectric vibrator having a value in the range of 0.75 to 2.