JPS6246399Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a piezoelectric speaker, and its purpose is to use a piezoelectric element with a structure in which a thin piezoelectric ceramic plate is bonded to a thin metal diaphragm having a wider area. Another object of the present invention is to provide an inexpensive and lightweight piezoelectric speaker that does not require a separate housing part, has a simple mounting structure, and does not generate magnetic force or chattering noise unlike electromagnetic speakers. .

Conventionally, piezoelectric speakers have the configuration shown in Fig. 4, in which 8 is a case with a bottom, and the periphery of a piezoelectric element consisting of a diaphragm 11 to which a piezoelectric ceramic plate 10 is pasted is fixed with adhesive. There is. Reference numeral 9 denotes an upper lid having a large number of sound emitting holes 13. 12 is a terminal for electrical connection with the outside. If such a configuration is adopted, since the diaphragm 11 is fixed to the case 8 with an adhesive, the vibration of the piezoelectric element will leak and the sound will be jarring. In addition, in order to expand the sound range to the low range, it is necessary to increase the diameter or thinner the diaphragm or piezoelectric ceramic plate, which is difficult in terms of construction, and it is difficult to expand the sound range to the low range below 500Hz. It was difficult.

The present invention solves the above-mentioned drawbacks, and the structure thereof will be explained below with reference to the drawings showing an embodiment of the present invention.

Fig. 1 shows a front view of the piezoelectric speaker of the present invention, and Fig. 2 shows a cross-sectional view, in which a piezoelectric element made by laminating a piezoelectric ceramic plate 2 to a thin metal diaphragm 1 is simultaneously molded into a plastic case 3. It was insert molded and fixedly held in the insert molding part 4. The outer shell 6 of the plastic case 3 is
It is made thick enough so that it will not be shaken by the vibrations of the piezoelectric element. The annular vibrating part 5 between the insert molding part 4 and the outer part 6 of the plastic case 3 is molded to have a small thickness, so that the annular vibrating part 5 itself can generate a second vibration that resonates without eliminating the vibration from the piezoelectric element. It was constructed to function as a board. 7 is a mounting hole for a piezoelectric speaker.

Since the present invention has the above-mentioned configuration, the annular vibrating part 5 is equivalent to increasing the diameter of the diaphragm 1, and the reproduced sound range is lowered as shown in Fig. 3A. I was able to expand it to. FIG. 3B shows the frequency characteristics of the conventional example. Furthermore, since the outer shell 6 is molded thickly, vibrations are sufficiently suppressed, and the plastic case 3 hardly resonates, so there is no chatter in the sound. In addition, since the piezoelectric element does not need to be glued to the plastic case 3, it is simple and inexpensive to construct, and if the molding conditions are well controlled, it is possible to obtain uniform characteristics.
We were able to provide a piezoelectric speaker that has a simple installation structure and does not generate magnetic force like electromagnetic speakers.

[Brief explanation of the drawing]

Figure 1 is a front view showing the piezoelectric speaker of the present invention, Figure 2 is a sectional view of the same, Figure 3 A is an example of the frequency characteristics of the present invention, B is an example of the frequency characteristics of the conventional example, and Figure 4 A is the conventional example. A front view showing , and a sectional view of the same. DESCRIPTION OF SYMBOLS 1... Vibration plate, 2... Piezoelectric ceramic plate, 3... Plastic case, 4... Insert molding part, 5...
... Annular vibrating part, 6... Outer part.

Claims (1)

[Scope of utility model registration request] A plastic case that holds the outer periphery of a piezoelectric element, which has a structure in which a thin piezoelectric ceramic plate is bonded to a thin metal diaphragm having a wider area, is formed by insert molding the outer periphery of the piezoelectric element at the same time as the plastic case is molded. This piezoelectric speaker has a thin annular vibrating section molded between the insert molding section and the thick outer shell of the plastic case.