JPH0419917Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention: [Field of industrial application] This invention relates to a speaker using a piezoelectric film as a vibrating body.

[Prior art] Speakers using piezoelectric films as vibrating bodies have been developed using patent application publication No. 12432/1988 (title of invention: electroacoustic transducer) and publication of utility model application No. 1983/41476 (name of invention: speaker).

Problems to be Solved by the Invention] Although such conventional devices have wide directivity, they have the disadvantage that the frequency band of electroacoustic conversion cannot be set broadly.

The purpose of this invention is to provide a speaker that has a wide directivity and can set a wide frequency band for reproduced sound.

Structure of the invention: The speaker of this invention has several piezoelectric vibrating films 1 of different thicknesses on the outer peripheral surface of a cylindrical porous elastic body 2, each of which is slightly elastically compressed by the porous elastic body 2. This configuration is characterized in that they are arranged side by side in the axial direction of the cylinder.

[Example] The length x width dimensions are the same 100 mm x 100 mm, and the thickness is 9
Polymer piezoelectric vibrating films 1a, 1b, and 1c of 52 microns, 28 microns, and 52 microns are placed on the outer peripheral surface of a porous elastic body 2 formed into a cylindrical shape of soft urethane foam, in order from the bottom in the axial direction of the cylinder. A molecular piezoelectric vibrating film 1a, a 28-micron polymer piezoelectric vibrating film 1b, and an 8-micron polymer piezoelectric vibrating film 1c are arranged in a porous elastic body 2 formed into a cylindrical shape of soft urethane foam so as to be slightly elastically compressed. It has been set up. A 52 micron polymer piezoelectric vibrating film 1a is placed between the porous elastic body 2 formed into a cylindrical shape of soft urethane foam.
This forms the speaker SP1, and the 28 micron polymer piezoelectric vibrating film 1b serves as the speaker.
SP2 is formed, and a speaker SP3 is formed using a 9 micron polymer piezoelectric vibrating film 1c.
The input terminals of these speakers SP1, SP2, and SP3 are connected in parallel.

Figure 2 A shows the sound pressure frequency characteristics of speakers SP1, SP2, and SP3, and Figure 2 B shows the sound pressure frequency characteristics of speakers SP1, SP2, and SP3.
This is a sound pressure frequency characteristic of an embodiment of this invention, which is a composite of the sound pressure frequency characteristics of SP1, SP2, and SP3. The sound pressure frequency characteristics in Figure 2 B are the speaker SP in Figure 2 A.
The frequency band of the reproduced sound is wider than any of the sound pressure frequency characteristics of SP1, SP2, and SP3. Since the polymer piezoelectric vibrating films 1a, 1b, and 1c are arranged so as to surround the outer peripheral surface of the cylindrical porous elastic body, the directivity of the sound pressure frequency characteristics is approximately 360°, although not shown. spread in the direction.

In this embodiment, the thickness of the polymeric piezoelectric vibrating film 1 is 9 microns, 28 microns, and 52 microns, but other combinations may be used as appropriate.

Effect of the invention: By selecting the thickness of the polymer piezoelectric vibrating film 1 with different thicknesses and selecting the number of polymer piezoelectric vibrating films 1, the frequency band of the reproduced sound can be appropriately set to a wide range.

[Brief explanation of the drawing]

Fig. 1 is a perspective view illustrating the speaker of this invention, Fig. 2 A is a sound pressure frequency characteristic diagram illustrating an embodiment of this invention, and Fig. 2 B is a sound pressure frequency of the speaker in an embodiment of this invention. A characteristic diagram is shown. 1...Polymer piezoelectric vibrating film, 1a, 1b,
1c...Polymer piezoelectric vibrating film having different thicknesses, 2...Cylindrical porous elastic body, 3...Cylindrical punching metal. 4...Sound absorbing material, 5...
The stand.

Claims (1)

[Scope of utility model registration request] A plurality of piezoelectric vibrating films having different thicknesses are arranged on the outer circumferential surface of a cylindrical porous elastic body in the axial direction of the cylinder so as to slightly elastically compress the porous elastic body. speaker.