JPS60214200A - Piezoelectric electroacoustic transducer - Google Patents

Abstract

PURPOSE:To obtain uniform reproducing response over a wide band by using a nodal position of the 1st and 2nd resonance frequencies of a piezoelectric element so as to connect the piezoelectric element and a cone form diaphragm. CONSTITUTION:The cone form diaphragm 5' has a long diameter part 8, a short diameter part 9 and a bottom 10. A bottom 10-1 of the long diameter part 8 and a bottom 10-2 of the short diameter part form a regular ellipse or a curve close to an ellipse respectively where the nodal diameter of the 1st resonance frequency and the nodal diameter of the 2nd resonance frequency are used respectively as the major and the minor axes of the ellipse respectively. A piezoelectric element disc 1 and the bottom of the cone are bonded by a means of bonding in terms of line or face. The resonance mode is scattered since the cone bottom 10 of the cone form diaphragm 5' and the piezoelectric element disc 1 are bonded by using the nodal position of the 1st and 2nd resonance frequencies in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a piezoelectric electroacoustic transducer that is widely used in general audio, such as high-pitched speakers and microphones.

(Conventional configuration and its problems) In recent years in the general audio industry, taking high-frequency speakers as an example, piezoelectric high-frequency speakers, which often require a low-frequency rejection filter for band division, are used to reduce costs. Figure 1 shows the cross-sectional configuration of an example of a conventional piezoelectric speaker for high-pitched sounds. 1 is a piezoelectric element disk, and many are of the bimorph type with an intermediate electrode inserted.
2 is a highly flexible cushioning material that allows for free vibration;
3 is the electrode lead wire of the piezoelectric element, from which an electric signal current is supplied; 4 is a frame made of a thin metal plate or resin;
Reference numeral 5 denotes a cone-shaped diaphragm made of paper or light metal foil, the lower end apex 6 of which is fixed to the piezoelectric element disc 1 by means of adhesive or the like, the upper part of the opening is glued to the frame 4, and the upper part is made of paper or the like. The configured gasket 7 is fixed.

In a high-pitched piezoelectric speaker with such a conventional configuration, only one point of the apex 6 of the cone-shaped diaphragm 5 is driven.
Only a large peak occurs in the frequency characteristics near the first resonance frequency of the piezoelectric element disk 1, and the reproduction efficiency of other frequencies is low.As a result, the speaker has an extremely narrow reproduction band, and it is difficult to improve its performance. There are some drawbacks.

FIG. 2 shows an example of the frequency characteristics of a conventional high-pitched piezoelectric speaker.

(Objective of the Invention) It is an object of the present invention to provide a piezoelectric electroacoustic transducer that eliminates the above-mentioned conventional drawbacks and enables uniform reproduction over a wide band.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention includes a conversion element which is larger than a piezoelectric element disk, a node of the first resonance frequency of the piezoelectric element disk is the long axis, and a node of the second resonance frequency of the piezoelectric element disk. a cone-shaped diaphragm made of paper or light metal foil having a regular elliptical or substantially elliptical bottom with a short axis of and an acoustic signal is generated by driving the piezoelectric element disk with an electric signal, or an electric signal is obtained from the piezoelectric element disk by applying a sound wave to the diaphragm. It is.

(Description of Embodiment) FIGS. 3(a) and 3(b) show the structure of an embodiment of a piezoelectric electroacoustic transducer according to the present invention, in which (a) is a vertical cross-sectional view, and (b) is a plane view. It is a diagram.

In the figure, 1 is a piezoelectric element disk, 2 is a flexible cushion material, 3 is an electrode lead wire of the piezoelectric element, 4 is a frame,
The configuration up to this point is completely unchanged from the conventional configuration shown in FIG. 8 indicates the long axis of the cone of the cone-shaped diaphragm 5', 9 indicates the short axis of the cone, 1° indicates the bottom of the cone, and the bottom 1o-1 on the long axis side corresponds to the first resonance frequency of the piezoelectric element disk 1. The diameter of the cylinder and the bottom part 10-2 on the minor axis side form a regular ellipse or a substantially ellipse with the cylinder diameter of the second resonance frequency as the major axis and minor axis of the ellipse, respectively, and the piezoelectric element disk 1 and the cone It is fixed to the bottom part 10 by means of line drawing or surface adhesion.

In this way, since the piezoelectric element disk l and the bottom part 1o of the cone of the cone-shaped diaphragm 5' are coupled using the node positions of the first and second resonance frequencies of the piezoelectric element, the resonance mode is dispersed. Ru.

Figure 4 shows an example of the frequency characteristics of the high-pitched piezoelectric speaker according to the present invention, and shows that the band in which a uniform sound pressure can be obtained is wider than the conventional example shown in Figure 2. ing.

(Effects of the Invention) As explained above, according to the present invention, the piezoelectric element and the cone-shaped diaphragm are coupled using the nodal positions of the first and second resonance frequencies of the piezoelectric element. The mode is dispersed, and a uniform playback response can be obtained over a much wider band than the conventional center-only drive.For the same reason, the same effect can be expected when used as a microphone. can. As described above, the present invention has the advantage that it is possible to obtain an electroacoustic transducer with high performance reproduction and great practical value without significantly changing the structure and, therefore, with almost no increase in cost. be.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a cross-sectional configuration of an example of a conventional piezoelectric speaker for high-pitched sounds, Fig. 2 is a frequency characteristic diagram of a conventional piezoelectric speaker for high-pitched sounds, and Fig. 3 is an embodiment of a piezoelectric electroacoustic transducer according to the present invention. FIG. 4 is a diagram showing an example of the configuration of an example, and FIG. 4 is a diagram showing an example of the frequency characteristics of the high-pitched piezoelectric speaker according to the present invention. 1... Piezoelectric element disk, 2... Cushion material, 3...
・Piezoelectric element electrode lead wire, 4...frame, 5.5
′... Cone-shaped diaphragm, 6... Apex, 7... Gasket, 8... Long diameter part of cone, 9... Short diameter side of cone, 10... Bottom of cone. Figure 1 7 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A paper or light metal having a conversion element consisting of a piezoelectric disk, and a regular elliptical or substantially elliptical bottom whose major axis is the node of the first resonance frequency of the piezoelectric disk and the minor axis is the node of the second resonance frequency. The diaphragm has a cone-shaped diaphragm made of foil, the elliptical bottom of the diaphragm is fixed to the piezoelectric element disk so as to be integrated, and the piezoelectric element disk is driven by an electric signal to generate an acoustic signal. 1. A piezoelectric electroacoustic transducer characterized in that an electric signal is obtained from a piezoelectric element disk by making a sound or applying a sound wave to the diaphragm.