JPH0441680Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a polymer piezoelectric vibrating element using a film of a polymer material having a pressure-to-electricity conversion function, such as polyvinidene fluoride.

[Prior Art] Acoustic transducers, such as speakers, using polymeric piezoelectric vibration elements have conventionally been widely used as speakers for reproducing high-pitched sounds, but this speaker has only the ability to reproduce high-pitched sounds in a limited frequency band. It's for a reason.

In order to solve this problem, various attempts have been made to widen the reproduction frequency range of such polymer piezoelectric speakers.

For example, since the reproduction frequency decreases as the film becomes thicker, a speaker that combines films of different thicknesses has been considered.

[Problems to be solved by the invention] However, since the film is only available in two or three different thicknesses on the market, it is difficult to obtain a film of a desired thickness easily and inexpensively. I had a problem that didn't exist.

[Means for solving the problem] In this invention, at least a portion of the surface of a polymer piezoelectric film having conductive layers formed on both sides is covered with an ultraviolet curable adhesive layer to form surfaces with different thicknesses. , is a polymer piezoelectric element characterized in that the surfaces having different thicknesses have different reproduction frequency bands.

[Function] This invention has the same effect as increasing the thickness of that part by layering an ultraviolet curable adhesive layer on the part, and by lowering the reproduction frequency band in that part, the reproduction frequency as a whole is increased. The band can be expanded.

[Example] This idea will be explained below with reference to examples.

FIG. 1 shows the first embodiment, in which a part B of a polymer piezoelectric film (on which a conductive layer is formed) formed into a wave-shaped curved surface is formed, except for the central part A. Also, the outermost edge portion C
has a thicker adhesive layer.

That is, after applying the ultraviolet curable adhesive 2a to the parts other than the part A by an appropriate means and curing it by irradiating ultraviolet rays, further applying the ultraviolet curable adhesive 2b only to the outermost edge part C, By curing by irradiating with ultraviolet rays, a polymer piezoelectric vibrating element having a part A without an adhesive layer, a part B with one layer of adhesive, and a part C with two layers of adhesive on a curved surface is produced. can get.

According to this configuration, the C section operates as a diaphragm for reproducing low frequencies, the B section operates as a diaphragm for reproducing medium frequencies, and the section A functions as a diaphragm for reproducing high frequencies.

FIG. 2 shows a second embodiment, in which a polymer piezoelectric film (with a conductive layer formed on the surface) 1 is formed into continuous waveform curved surfaces A, B, and C, and the C portion is formed as described above. Two adhesive layers 2a, 2b
The B part has a single adhesive layer 2a, and the A part has no adhesive layer.

According to this configuration, the C section operates as a diaphragm for low-temperature reproduction, the B section operates as a diaphragm for medium frequency reproduction, and the A section functions as a diaphragm for high frequency reproduction. Furthermore, since each waveform is formed into an independent waveform curved surface, the depth of the vibrating element can be reduced compared to the first embodiment if the same acoustic radiation efficiency is to be obtained.

FIG. 3 shows a third embodiment, in which a polymer piezoelectric film (with a conductor layer formed on the surface) 1 has a dome shape A in the center, an annular part B with a waveform curved surface connected to the dome, and Annular part C with a wavy curved surface on its outer periphery
are formed respectively.

The two adhesive layers 2a and 2b are formed on the C portion as described above, the single adhesive layer 2a is formed on the B portion, and no adhesive layer is formed on the A portion.

According to this configuration, the C section operates as a diaphragm for bass reproduction, the B section operates as a diaphragm for medium frequency reproduction, and the A section operates as a diaphragm for high frequency reproduction. In addition, since they are each formed into independent annular waveform curved surfaces, the depth of the vibrating element can be reduced in order to obtain the same acoustic radiation efficiency compared to the previous two embodiments, and since the external shape is circular, it is easier to assemble the speaker. It also becomes easier.

[Effect of the invention] According to the invention explained above, by partially layering the ultraviolet curable adhesive, the same effect as using piezoelectric films of different thicknesses can be obtained, and the adhesive layer Since the thickness can be freely selected, a vibrating element with desired acoustic characteristics can be easily obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the first embodiment of this invention, Figure 2 is a perspective view of the second embodiment of this invention, and Figure 3a.
Figures 3 and 3b are a top view and a sectional view of a third embodiment of the invention.

Claims (1)

[Scope of utility model registration request] At least a portion of the surface of the polymer piezoelectric film, which has conductor layers formed on both sides, is covered with an ultraviolet curable adhesive layer to form surfaces with different thicknesses, and the surfaces with different thicknesses each have different playback frequency bands. A polymer piezoelectric element characterized by having the following.