JPS63312800A - Electroacoustic transducer - Google Patents

Abstract

PURPOSE:To obtain a broad band electroacoustic transducer by arranging plural piezoelectric elements with different basic resonance frequency as the drive for same diaphragm so as to make the characteristic flat. CONSTITUTION:Piezoelectric element 2A, 2B are arranged in one and same plane of the flat diaphragm 1. The element 2A is used for a low resonance frequency and the element 2B is used for a high resonance frequency. Then the characteristic peak by the plural elements 2A, 2B with different basic resonance frequency is make flat by the diaphragm 1. Thus, the electroacoustic transducer with a broad band is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application IF) The present invention relates to electroacoustic transducers such as speakers or microphones.

(Prior art and its problems) Piezoelectric elements such as ceramic vibrators are small and lightweight, so they are expected to have many advantages when applied to electroacoustic transducers such as speakers and microphones. Generally, the resonance is too large and it is difficult to make the characteristics flat over a wide band.

(Means for Solving the Problems) The present invention has been proposed in view of the above points, and its purpose is to provide an electroacoustic device that can flatten characteristics over a wide band and take advantage of the advantages of piezoelectric elements. The purpose is to provide a converter.

In order to achieve the above object, the present invention provides an electroacoustic transducer characterized in that a plurality of piezoelectric elements having different fundamental resonance frequencies are arranged to drive the same diaphragm.

(Function) In the present invention, the characteristic peaks caused by the plurality of piezoelectric elements having different fundamental resonance frequencies are flattened by the diaphragm, so that the present invention can be fully put into practical use in electroacoustic transducers such as speakers and microphones.

(Example) DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing embodiments.

FIGS. 1 and 2 respectively show the first and second embodiments of the present invention, in which two piezoelectric elements and 2 bits are arranged in the same plane of a flat diaphragm 1. Note that the two piezoelectric elements have a low resonance frequency, and the piezoelectric element 2 has a low resonance frequency.
B has a high resonant frequency. Further, in the embodiment shown in FIG. 2, the diaphragm 1 is formed into an oval shape.

Figures 3 to 5 represent the third to fifth embodiments of the present invention, respectively.
This shows an example in which two piezoelectric elements 2B are provided behind the diaphragm 1, and piezoelectric elements 2A and 2 are provided on the diaphragm 1.
The vibrations of B are appropriately synthesized and transmitted. In addition, 1a is an edge, 3 is a connecting part, 4 is a holding part, 5 is a transmission part, and 6 is a frame.

In each of the above embodiments, the piezoelectric element can be of either a stretching vibration type or a bending vibration type (bimorph type). However, the bimorph type is more efficient. Also,
The number of piezoelectric elements is not limited to what is shown in the drawings, and may be any suitable number. Furthermore, from the viewpoint of distortion generation, it is preferable that the resonant frequency of the piezoelectric element is not selected to be an integral multiple of the resonant frequency of other piezoelectric elements. On the other hand, the materials for the diaphragm are paper, metal, and plastic.

Any material such as glass or ceramic can be used, and it is also possible to use not only a flat diaphragm but also a part or all of a structure of any shape.

Figure 6 shows the relationship (characteristics) between frequency and sound pressure of the electroacoustic transducer according to the present invention, and when there is no influence of the diaphragm, the characteristics change at the resonant frequency of each piezoelectric element as shown by the solid line. Mountains occur, but the shape.

By using a diaphragm made of appropriately selected materials and two dimensions, it is possible to obtain flattened characteristics as shown by the broken line.

(Effects of the Invention) As described above, in the electroacoustic converter of the present invention, since a plurality of piezoelectric elements having different fundamental resonance frequencies are arranged for driving the same diaphragm, the characteristics are flattened, and the piezoelectric elements This has the effect of providing a broadband electroacoustic transducer while taking advantage of its small size and lightweight characteristics.

[Brief explanation of the drawing]

1 to 5 are block diagrams showing the first to fifth embodiments of the electroacoustic transducer of the present invention, and Fig. 6 shows the relationship between frequency and sound pressure in the electroacoustic W transducer of the present invention. FIG. 1...Vibration plate, 1m...Edge, 2A
, 2B...Piezoelectric element, 3...Connection section, 4...Holding section, 5...Transmission N, 6.
...Frame patent applicant Michio Takayama', patent attorney Foster Electric Co., Ltd.'・4. I and 1 other person Figure 1 Figure 2

Claims (1)

[Claims] An electroacoustic transducer characterized in that a plurality of piezoelectric elements having different fundamental resonance frequencies are arranged to drive the same diaphragm.