Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS57163898 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a conventional piezoelectric sounding body, FIG. 3 is a plan view showing a piezoelectric diaphragm used for the piezoelectric sounding body, and FIG. FIG. 6 is a cross-sectional view showing an embodiment of the piezoelectric sounding body of the present invention, and FIGS. 7 to 9 are diaphragms of the piezoelectric sounding body according to the present invention. The top view which shows an Example, FIG. 10 is a sound pressure-frequency characteristic view of the piezoelectric sounding body by this invention. 8 ··· Case · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · elastic thin plate, 13 · · · · · · · · · · · · · · · · piezoelectric vibration plate DETAILED DESCRIPTION OF THE INVENTION In the present invention, a piezoelectric ceramic plate and an elastic thin plate such as a metal plate are bonded to each other, or a piezoelectric diaphragm which induces flexural vibration of one having piezoelectric ceramic plates laminated to each other. According to a piezoelectric sounding body that generates a direct sound from the piezoelectric diaphragm, the expansion of the frequency band and the flattening of the sound pressure-frequency characteristic are performed to generate a melody or a voice. As a conventional piezoelectric speaker, as shown in FIG. 1 to FIG. 4, the elastic thin plate 2 made of circular metal is circular at the -L portion of the case 1 as shown in FIG. 1 to FIG. Alternatively, the peripheral portion of the piezoelectric diaphragm 4 or the node portion of the piezoelectric diaphragm 4 formed by bonding the square-shaped piezoelectric ceramic plate 3 is supported by the projecting portion 5H of the case 1, and the lead wire 6 for applying the signal voltage is provided. Vibration by applying a signal voltage 4 is vibrated and sound from sound emission hole 7 of the front or case 1 of the piezoelectric diaphragm 4 has been a structure in which radiation. The piezoelectric sounding body has a feature of low power consumption, thinness and light weight, and has been used as a buzzer in many electronic devices in recent years. However, since this piezoelectric speaker has a very sharp resonance characteristic with the piezoelectric diaphragm 4, the sound pressure-frequency characteristic becomes very high near the resonance 11-05-2019 1 frequency as shown in FIG. The change was unremarkably large, and it was not possible to reproduce natural sound with emphasis on sound power of a specific frequency as the factory Lithea force that generates melody and voice. The resonance frequency of the piezoelectric diaphragm 4 in the 853 piezoelectric speaker is determined by the material, thickness, diameter and support structure of the piezoelectric diaphragm 4 of the piezoelectric diaphragm 4, and the fundamental first resonance and second or higher harmonics Resonance occurs. When the piezoelectric diaphragm 4 is circular as in the prior art, the first and second or higher order resonance frequencies appear one by one according to the diameter of the piezoelectric diaphragm 4 and the resonance Q is very high. Because the sound pressure in the vicinity of the resonance frequency and the sound pressure at the other frequencies are largely different, the characteristics become as shown in FIG. In FIG. 5, fl is a first order, f2 is a second order, and f5 is a third order resonance frequency. In particular, when circular vibration is supported at the periphery, the ratio h / f + of the first and second resonance frequencies is about 3.9, and the ratio + 3 / f2 of the second and third resonance frequencies is about 2. As the distance between the respective resonance frequencies is wide, there is a disadvantage that the sound pressure is greatly reduced particularly in the middle of them. The present invention eliminates the abovementioned conventional drawbacks. That is, the present invention provides a piezoelectric sounding body in which the piezoelectric diaphragm has an elliptical shape 864 and has many resonance frequencies. Hereinafter, an embodiment of the present invention will be described with reference to FIG. 6 to FIG. First of all, in FIG. 6, 8 is a case of open upper surface made of synthetic resin or the like, and a sound emission hole 9 is provided on the bottom surface of the substrate 8 and a step 10 is provided on the inner periphery of the earth portion. It is provided. A peripheral portion of a piezoelectric diaphragm 13 made of an elastic thin plate 12 made of metal or the like to which the piezoelectric ceramic plate 11 is attached is bonded to the case 80 step portion 10 by adhesion or the like. A lead wire 14 is connected to the piezoelectric ceramic plate 119 elastic thin plate 11, and this lead wire 14 is used for applying a signal application voltage and is drawn out of the case 8. As shown in FIG. 7, the piezoelectric diaphragm 13 has an elliptical shape for both the piezoelectric ceramic plate 111 and the elastic thin plate 12, and as shown in FIG. 8, the piezoelectric ceramic plate 11 is circular and the elastic thin plate 12 has an elliptical shape. Furthermore, as shown in FIG. 9, short straight portions may be made continuous to form an oval shape having a large nine-square shape. Further, as another piezoelectric vibration plate 13, two elliptical piezoelectric ceramic plates may be bonded. The elliptical piezoelectric vibrating plate 13 can be considered as a composite of a circular vibrating plate whose diameter continuously changes from the length a of its major axis to the length b-4 of its minor axis. The next resonant frequency is also determined by the major axis a. 決 ま る, determined by the minor axis from a. It can exist continuously up to + Ib. Similarly, the high-order primary resonance frequency can be continuously present from fna determined by the major axis a to fnb determined by the minor axis, and it is possible to generate a senden diaphragm 13 having a very large number of 11-05-2019 2 resonant frequencies. can do. In particular, it has an elliptical shape so that f, b determined by the short axis of the highest frequency in the first resonance frequency is slightly lower than f 2 L determined by the long axis a of the lowest frequency in the second resonance frequency The major axis length a and the minor axis length b of the piezoelectric diaphragm 13 are set so that the primary resonance and the secondary resonance of the elliptical diaphragm 13 generate almost continuous frequencies, and so on. The second and third resonances, and higher order resonances above -9 also generate frequencies 868 continuously. Therefore, the sound pressure cage generated between the resonance frequencies is also reduced, and the frequency response change of the sound pressure can be reduced as a whole. Since the resonant frequency is inversely proportional to the square of the diameter of the piezoelectric diaphragm, assuming that the proportional constant is K, +, a = / a2. f, b = / b '! And 2 / -f as described above. Since 39: F2a = s, sx / a ', so that: FIb = to / b' 43. sK / a '=, ((2aK1 ヨ ウ Kt Le K Ha b ˜ 472.0 1) It is most preferable to set the minor axis length b of the ellipse a little larger than 1 / 2.0 of the major axis length a It is effective. Piezoelectric sounding body peripherally supported on case 8 as shown in FIG. 6 according to the elliptical piezoelectric diaphragm of the present invention of FIG. 7 in which the length b of the short axis is set to 1 / 1.6 of the length a of the long axis The sound pressure-frequency characteristics of are shown in FIG. As shown in this characteristic, the piezoelectric sounding body using the earth electrode diaphragm according to the present invention has a conventional level change due to the sound pressure frequency (smaller compared to the conventional one, and the range is expanded, resulting in natural voice and melody If the piezoelectric sounding body is used as a speaker terminal 897, the present invention is very effective and highly useful. 11-05-2019 3
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