JPH0418320Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to the structure of a piezoelectric speaker using a polymeric piezoelectric film as a diaphragm in the field of electroacoustic equipment.

[Prior Art] In the conventional structure of a piezoelectric speaker, which uses a flexible polymer piezoelectric film as a diaphragm with electrodes on both sides, when an electric signal is applied to the electrodes, the polymer piezoelectric film Since the vibrations stretch and contract in the directions, the acoustic conversion efficiency is extremely low if left as is.Therefore, in order to convert the vibrations in the plane direction into vibrations in the direction perpendicular to the plane, a typical structure with the characteristics shown in Figure 3 is used as a typical example. As seen in the specification and drawings of Publication No. 54-12213, a diaphragm 21 made of a polymeric piezoelectric film is held by a frame 22 and a substrate 23 so as to have a cylindrical surface or a shape of a combination of cylindrical surfaces. However, by making it a cylindrical surface, expansion and contraction in the surface direction is converted into deviation in the direction perpendicular to the surface. In order to prevent split vibration of the diaphragm and to efficiently convert such vibration modes, the inside of the cylindrical diaphragm is filled with a low-density elastic material 24 such as foamed resin or class wool. A constant tension is applied to the diaphragm 21.

[Problem to be solved] The frequency characteristics of the piezoelectric speaker with the conventional structure described above depend on the tension and dimensions of the diaphragm. Therefore, when mass-producing a speaker with this type of structure, it is necessary to avoid errors due to inherent errors in factors that affect the tension of the diaphragm, such as the amount of elastic material and the dimensions of the diaphragm support. However, the drawback was that it was not possible to obtain stable speaker performance.

Therefore, in the present invention, we have developed a piezoelectric type that eliminates the drawbacks of the conventional example and stabilizes the performance by making the tension of the diaphragm constant by making simple adjustments during assembly. The purpose is to obtain a speaker.

[Means for Solving the Problems] The structure of the piezoelectric speaker according to the present invention for achieving the above object will be explained with reference to FIGS. 1 and 2 showing examples. A diaphragm 1 made of a polymeric piezoelectric film having a diaphragm 1, a substrate 2 having a protruding adhesive frame 2a for attaching and extending the diaphragm 1, and a low-density film filled between the substrate 2 and the diaphragm 1. diaphragm 1 by pressing a part of the diaphragm 1 onto the elastic body 3 from above.
a plurality of presser rods 4 that apply tension to the presser rods 4;
It consists of a frame 5 which presses and holds the diaphragm on the diaphragm, a spring 6 interposed between the frame 5 and the substrate 2, and an adjustable coupling means 7 such as a screw which couples the frame 5 and the substrate 2. , has a structure in which a frame body 5 is adjustably attached to the base plate 2 so as to apply a predetermined tension to the diaphragm.

[Function] In the piezoelectric speaker having such a structure, when the frame 5 is attached to the substrate 2 via the spring 6 by the coupling means 7, the tightening amount of the coupling means 7 is adjusted to tighten the frame 5. By adjusting the pressing force with which the held presser rod 4 presses the diaphragm 1 from above against the elastic body 3, the tension acting on the diaphragm can be adjusted. At this time, the spring 6 tries to spread the space between the frame 5 and the substrate 2 against the tightening force of the screw 7, and reliably maintains the adjusted mutual position of the frame 5 and the substrate 2.

[Example] In Figs. 1 and 2, reference numeral 1 denotes a flexible diaphragm having electrodes formed by vapor-depositing metal on both sides of a polarized polyvinylidene fluoride film.

Reference numeral 2 denotes a substrate for holding the diaphragm 1 in an extended manner, and has two adhesion parts 2a protruding from the top surface to which the diaphragm is attached.

The diaphragm 1 has both sides attached to the adhesive part 2 so as to be bridged.
It is attached and held on a.

A low-density elastic body 3 is placed between the substrate 2 and the diaphragm 1.
The diaphragm 1 is filled with glass wool in an amount sufficient to apply tension to the diaphragm 1.

Reference numeral 5 denotes a frame body, and three presser rods 4 are attached to a square hole exposing the diaphragm 1 to press a part of the diaphragm 1 from above against the elastic body 3.

The frame body 5 is attached to the substrate 2 with screws 7 as coupling means via springs 6, and the three presser rods 4 press the diaphragm 1 at three places, so that the diaphragm 1 is shaped like a wave with continuous cylindrical surfaces. do. Each cylindrical surface portion of the diaphragm 1 is given tension by the expansion force of the filled elastic body 3 made of glass wool.

Although typical embodiments of the present invention have been described in detail above, the structure of the piezoelectric speaker of the present invention is not limited to the above embodiments. For example, changing the material of the piezoelectric polymer film or elastic body to another material with equivalent properties, or changing the spring to a plate spring or elastic rubber instead of a coil spring, etc., can satisfy the structural requirements of the present invention. However, the present invention can be modified and implemented as appropriate within the scope of maintaining the functions and effects of the present invention.

[Effects] The piezoelectric speaker according to the present invention described above has a structure in which the frame 5 is attached to the substrate 2 via the spring 6 with the machine screws 7. Therefore, the amount of tightening of the machine screws 7 can be adjusted to adjust the amount of tightening of the frame body 5. The tension acting on the diaphragm can be adjusted by adjusting the pressing force with which the presser rod 4 held at the diaphragm 5 presses the diaphragm 1 from above against the elastic body 3.

Therefore, as in the conventional example, even if there are errors in the dimensions of other components, it is possible to maintain the performance of the speaker at a constant level, and the piezoelectric speaker has the advantage of being highly mass-producible.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a piezoelectric speaker according to the present invention, FIG. 2 is a partially cutaway perspective view, and FIG. 3 is a sectional view of a conventional example. 1 is a diaphragm, 2 is a substrate, 3 is an elastic body, 4 is a presser bar, 5 is a frame body, 6 is a spring, and 7 is a screw.

Claims (1)

[Scope of utility model registration request] A diaphragm 1 made of a flexible polymeric piezoelectric film with electrodes on both sides, a substrate 2 with a sticking frame 2a protruding from which the diaphragm 1 is attached and extended, and the substrate 2 and the diaphragm 1. a low-density elastic body 3 filled in between, a plurality of presser rods 4 that apply tension to the diaphragm 1 by pressing a part of the diaphragm 1 from the upper surface onto the elastic body 3, and the presser rods 4. A frame body 5 that presses and holds the frame body 5 on the diaphragm, a spring 6 interposed between the frame body 5 and the substrate 2, and an adjustable coupling means 7 such as a screw that connects the frame body 5 and the substrate 2. A frame body 5 is configured to apply a predetermined tension to the diaphragm.
A piezoelectric speaker characterized in that a piezoelectric speaker is adjustably attached to a substrate 2.