JP2001285994A - Piezoelectric speaker and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric speaker capable of flattening frequency characteristics and reducing distortion and a method for manufacturing the piezoelectric speaker for easily forming the damper material of a uniform film thickness. SOLUTION: In this piezoelectric speaker provided with piezoelectric bodies 12 and 13 and a metal diaphragm 11 attached to a frame body and provided with a diaphragm part 31 for constituting a piezoelectric vibrator together with the piezoelectric bodies 12 and 13 and an elastic supporting part 33 for elastically supporting it for which the damper material 40 is loaded between the diaphragm part 31 of the metal diaphragm 11 and the frame body, the damper material 40 is formed of a part of polymer films 41 and 42 stuck to the metal diaphragm 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric speaker having a vibrator using a piezoelectric body and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a small and low-current driven acoustic device using a piezoelectric body as an electroacoustic transducer has been known. For example, a small-sized device such as a cassette tape recorder or a micro-cassette tape recorder has an acoustic output device. Has been used as

Recently, this type of piezoelectric speaker has a planar shape, and is provided with a metal diaphragm made of a metal thin film and an edge material for elastically supporting the metal diaphragm so as to be able to vibrate with respect to an outer frame. Have been. The edge material is formed by applying a polymer solution to a metal diaphragm and forming a polymer film as a damper material having rubber elasticity (viscoelasticity like rubber) on a peripheral portion thereof. The damper material here partitions the front and rear spaces in the vicinity of the outer peripheral portion of the metal diaphragm, and becomes a portion having a low mechanical impedance and a large internal loss, and unnecessary peaks due to surface resonance of the metal diaphragm. (Mountain) / Dip (valley), plays the role of suppressing distortion and the like.

In forming the damper material, a dipping method in which a metal diaphragm is immersed in a polymer solution or a brush-coating method in which a polymer solution is applied to a metal diaphragm with a brush are usually employed. In addition, a method of filling a gap between a diaphragm portion of a metal diaphragm and a portion surrounding the diaphragm portion with a polymer material by utilizing a capillary phenomenon has been adopted.

[0005]

However, in the above-described conventional piezoelectric speaker and the method of manufacturing the same, in order to form a damper material, a metal diaphragm is dipped in a polymer solution, or the polymer diaphragm is dipped. Since the solution was brush-painted onto the metal diaphragm, it was difficult to evenly fill the gap around the metal diaphragm with the polymer solution. It was difficult to make the uniform. Therefore, the sound pressure-frequency characteristic of the piezoelectric speaker is flattened, and the damper characteristic of suppressing the distortion of the generated sound with respect to the audio signal cannot be sufficiently exhibited, so that there is a problem that an acoustic characteristic corresponding to high sound quality cannot be obtained. .

Further, there is another problem that a pinhole is easily generated in the polymer film forming the damper material, and an air leak occurs to deteriorate acoustic characteristics.

Further, an electrode or the like for applying a sound current is formed on the piezoelectric body adhered to the metal diaphragm, but bubbles are mixed into the polymer coating film covering the electrode, and the insulating performance of the piezoelectric speaker is reduced. There is also a problem that the water resistance / moisture proof performance is deteriorated by the pinhole.

Accordingly, an object of the present invention is to provide a piezoelectric speaker capable of flattening frequency characteristics and reducing distortion, and a method of manufacturing a piezoelectric speaker capable of easily forming a damper material thereof.

[0009]

In order to solve the above-mentioned problems, a piezoelectric speaker according to the present invention comprises a piezoelectric body, a diaphragm attached to a frame, and constituting a piezoelectric vibrator together with the piezoelectric body. A metal diaphragm having an elastic support portion for elastically supporting the plate portion on the frame via a plurality of bending arm portions, wherein a damper material is provided between the diaphragm portion of the metal diaphragm and the frame. Wherein the damper member is formed of a polymer film having a predetermined thickness bonded to the metal diaphragm.

[0010] In this piezoelectric speaker, the damper material to be loaded between the diaphragm portion of the metal diaphragm and the frame is formed of a polymer film having a predetermined film thickness bonded to the metal diaphragm. The thickness of the damper material formed between the bending arm portions becomes uniform depending on the thickness of the polymer film, so that the frequency characteristics can be flattened and the distortion component can be reduced.

In the above piezoelectric speaker, the damper member is formed by joining polymer films disposed on both sides of the metal diaphragm between the diaphragm portion and the frame.
It is preferable that it is mounted between the diaphragm and the frame. This is because the lamination of the polymer films facilitates the loading of the damper material.

It is more preferable that the polymer film is laminated on the metal diaphragm with the metal diaphragm and the piezoelectric body sandwiched from both sides. With this configuration,
Waterproofing and moistureproofing of the piezoelectric body becomes possible.

A method for manufacturing a piezoelectric speaker according to the present invention comprises:
A metal diaphragm having a diaphragm portion and an elastic support portion for elastically supporting the diaphragm portion through a plurality of flexure arms, comprising a piezoelectric body bonded to the diaphragm portion to constitute a piezoelectric vibrator of a piezoelectric speaker And a polymer film that can be bonded to the metal diaphragm, and heating and pressurizing the polymer film in a state where the polymer film is overlaid on the metal diaphragm, and bonding the polymer film to the metal diaphragm. At the same time, a damper member made of the polymer film is loaded between the diaphragm portion and the elastic support portion of the metal diaphragm.

In this method for manufacturing a piezoelectric speaker, the polymer film is pressed against the metal diaphragm while being heated, so that the polymer film is bonded to the metal diaphragm at the same time.
Since a damper material consisting of a part of the polymer film is loaded between the diaphragm portion and the elastic support portion of the metal diaphragm and between the plurality of flexure arms, the periphery of the diaphragm and the periphery of the flexure arm are loaded. Can be surrounded by a polymer film having a constant thickness, respectively, and the damper material can be quickly formed.

Further, polymer films are laminated on both sides of the metal diaphragm, respectively, and both polymer films are joined between a diaphragm portion and an elastic support portion of the metal diaphragm to form the diaphragm portion and the elastic support portion. When the damper material is formed between the elastic support portions, the loading of the damper material is facilitated by laminating the polymer films.

Further, in the above-described method for manufacturing a piezoelectric speaker, a band-shaped film in which a separator is bonded to one surface of the polymer film with a lower adhesive force than the other surface of the polymer film is provided on both sides of the metal diaphragm. Placed on the side,
While laminating the polymer film of the band-shaped film on both sides of the metal diaphragm, pressing the separator of the band-shaped film from the back side of the polymer film toward the metal diaphragm, after the pressurization It is preferable that the separator be separated from the laminate of the metal diaphragm and the polymer film. In this configuration, the thin film polymer film can be superimposed on the metal diaphragm while being kept in a predetermined shape by the separator, and by appropriately selecting the material of the separator, the polymer film can be interposed between the diaphragm and the diaphragm portion through the separator. It can be securely brought into close contact with the outer edge portion and the elastic support portion.

[0017]

Preferred embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are views showing a piezoelectric speaker according to one embodiment of the present invention.

First, the configuration will be described. As shown in FIG. 1, the piezoelectric speaker according to the present embodiment includes a piezoelectric element 10 and an outer frame 20 supporting an outer peripheral portion of the piezoelectric element 10. The piezoelectric element element 10 includes a metal vibrating plate 11 made of a thin metal plate for a spring, for example, a thin plate of a stainless alloy such as 42 alloy (for example, a plate thickness of 100 microns), and the metal vibrating plate 11.
And piezoelectric members 12 and 13 made of, for example, PZT (lead zirconate titanate). The outer frame 20 has a plurality of, for example, four mounting holes 20a (a U-shaped or other notch may be used).

The metal vibrating plate 11 includes a vibrating plate portion 31 that forms the piezoelectric vibrator 15 with the piezoelectric members 12 and 13 adhered to both sides with known rubber-based adhesives 12 a and 13 a, and the vibrating plate portion 31. The diaphragm 31 includes an elastic supporting portion 33 that elastically supports the piezoelectric body 1 as shown in FIG.
It has four substantially rectangular vibrating portions 31b extending obliquely in four directions from a central portion 31a to which the second and the 13 are attached, and has a line-symmetrical shape in the left, right, up, and down directions. 2 and 3
As shown in the figure, on the outer peripheral portion of the elastic supporting portion 33 of the metal diaphragm 11, an electrode lead wire portion 11a protruding outward is provided.
A positioning round hole 11b and an oval hole 11c are provided.

The piezoelectric body 12 on one side is formed in a shape extending in four oblique directions, and the piezoelectric body 13 on the other side is formed in a circular shape. The two piezoelectric bodies 12 and 13 are connected to each other by a surface electrode jumper wire (for example, urethane wire) 51 (see FIGS. 2 and 3), and an electrode lead wire (for example, urethane stranded wire) 52 from the piezoelectric body 12 is placed outside. One terminal 55a of the relay board 55 mounted on the frame 20
(For example, a plus terminal), while the metal diaphragm 1
1 lead wire portion 11a is connected to the other terminal 5 of the relay board 55.
5b (for example, a negative terminal). And, between the positive and negative terminals 55a and 55b of the relay board 55,
When an audio input voltage (AC signal) within a predetermined frequency range is applied, the piezoelectric bodies 12 and 13 are deformed into a concave or convex shape according to the frequency, and the diaphragm 31 of the metal diaphragm 11 vibrates. , Sound is generated.

On the other hand, as shown in FIG.
Is straight up, down, left and right between a rectangular inner frame portion 34 surrounding the diaphragm portion 31, an outer frame attachment portion 35 attached to the outer frame 20, and a center portion 31a of the diaphragm portion 31 and the inner frame portion 34. Pairs of first flexure arms 32a, 32b spanned across
A plurality of pairs of second bending arms 32c and 32d bridged between the vibrating portions 31b of the vibrating plate portion 31 and the vicinity of the center of each side of the inner frame portion 34, and four inner corners of the inner frame portion 34 The four third bending arm portions 36a bridged between the respective vibrating portions 31b and the inner frame portion 34 at the four corners of the inner frame portion 34
And four fourth flexible arms 36b bridged between the outer frame mounting portion 35 and the inner frame portion 34 at the center of each side of the inner frame portion 34.
A pair of left and right fifth
And the bending arm portion 37.

Here, a pair of upper and lower second flexure arms 32 is provided.
4 are symmetrically arranged near the center of the metal diaphragm 11 in the left-right direction in FIG. 4 with the first bending arm portion 32a interposed therebetween, and extend in the longitudinal direction of the metal diaphragm 11 in a substantially U-shape. It has a folded arm shape. The pair of left and right flexure arms 32d are arranged vertically symmetrically around the center of the metal diaphragm 11 in the vertical direction in FIG. 4 with the first flexure arm 32b interposed therebetween.
Are extended in the longitudinal direction, and are folded in a substantially U-shape in opposite directions.

The inner frame portion 34 is substantially rectangular and has a pair of long and short bending arms 34a, 34b supported at both ends by a pair of adjacent bending arms 36b.
The first bending arm 32a or 32b and the second bending arm 32c or 32d are arranged at the center of the a and b.

A plurality of flexure arms 32a to 32 between the diaphragm 31 and the elastic support 33 of the metal diaphragm 11 are provided.
D, 34a, 34b, 36a, 36b and 37 (between diaphragm 31 and frame 20) are loaded with a damper material 40 as shown in FIGS.

The damper member 40 is formed by combining polymer films 41 and 42 disposed on both sides of the metal diaphragm 11 with the diaphragm portion 3.
1 and the frame 20, that is, between the diaphragm 31 and the outer frame mounting portion 35 of the elastic support 33,
By directly bonding and joining between 2a to 32d, 34a, 34b, 36a, 36b, and 37, the metal diaphragm 11 is loaded into a plurality of slit-shaped holes between the bending arms.

The polymer films 41 and 42 are resin films having rubber elasticity, for example, elastomer sheets made of butadiene / styrene copolymer (SBR), and have a thickness of about の of the metal diaphragm 11. (For example, 50 microns). These polymer films 41 and 42
Can sufficiently follow the surface and the notch shape of the metal vibration plate 11 and are directly adhered between the vibration plate portion 31 and the elastic support portion 33 (between the bending arm portions). The thickness 40 is substantially the same as the thickness of the metal diaphragm 11.

The polymer films 41 and 42 are formed by forming an adhesive layer (not shown) on at least the surface facing the metal diaphragm 11, or are pretreated so that they have adhesiveness. The rubber elastic film having a predetermined hardness is formed by applying pressure and heating the metal vibration plate 11 in a state where the rubber vibration film is adhered.

When the piezoelectric speaker is manufactured as described above, the diaphragm 31 and its elastic support 33 are prepared in advance.
Are prepared, and the piezoelectric bodies 12, 13 are provided with rubber adhesives 12a, 13a.
Is attached to the diaphragm 31. And the piezoelectric body 12,
13 are connected to each other by a surface electrode jumper wire 51, an electrode lead wire 52 from the piezoelectric body 12 is connected to one terminal 55a of the relay board 55, and a lead wire portion 11a of the metal vibration plate 11 is connected to the other terminal of the relay board 55. 55b,
Connect each one.

Further, polymer films 41 and 42 that can be laminated on the metal diaphragm 11 are prepared. In this embodiment, the cut polymer films 41 and 42 are not used as they are, but as shown in FIG. , Polymer film 41, 4
Adhesion to one surface (one surface side) of the polymer film sheets 101A, 101B from which the polymer film 2 can be cut out at an arbitrary portion is weaker than the adhesion surface (the other surface) of the polymer film sheets 101A, 101B to the metal diaphragm 11 The band-shaped separators 102A and 102B are bonded together by force to form band-shaped films 100A and 100B, respectively.
Rolls 0A and 100B are respectively prepared, and these strip films 100A and 100B are arranged on both sides of a predetermined laminating position.

Next, as shown in FIG.
13 is transferred in the direction of a white arrow (lamination position side) in the figure by a transfer means (not shown) by a transfer means (not shown), and the polymer film sheets 101A and 101B of the strip films 100A and 100B are transferred to the metal sheet. While laminating on both sides of the diaphragm 11, the belt-shaped films 100A,
00B separators 102A and 102B from the back side of the polymer film sheets 101A and 101B.
It is transported while hot pressing toward 1. That is, the polymer film sheets 101A and 101B are heated and pressed in a state where the polymer film sheets 101A and 101B are superimposed on the metal vibration plate 11 by the provisional pressure contact rolls 201 and 202, and the polymer films 41 and 42 are attached to the metal vibration plate 11 at the same time. The plurality of bending arms 32a to 32d, 34a, 34b, 36a, and 3 between the diaphragm portion 31 and the elastic support portion 33 of the metal diaphragm 11;
A damper material 40 composed of a part of the polymer films 41 and 42 is loaded between 6b and 37. At this time, all holes of the metal diaphragm 11 are closed by the polymer films 41 and 42.

Next, the separators 102A, 1A
02B is the metal diaphragm 11 and the polymer film sheet 1
It is peeled off from the laminated sheet portion 110 which is a laminate of 01A and 101B. At this time, the separators 102A, 10A separated from the laminated sheet portion 110
2B is a separator take-up roll 111A, 111B
It is wound up.

In addition, such a series of works can be transported, and the belt-like films 100A, 100B are provided with a predetermined tension on the upstream side of the pre-pressing rolls 201, 202 so that a predetermined tension is applied to the belt-like films 100A, 100B. Film 100A,
100B is sequentially rotated in the film feeding direction, and simultaneously, the separator winding rolls 111A and 111B are rotated in the winding direction.

The laminated sheet portion 110 is further hot-pressed by main pressing rolls 203 and 204, and the polymer films 41 and 42 are permanently pressed to the metal diaphragm 11.

The laminated sheet portion 110 hot-pressed by the main pressing rolls 203 and 204 is then cut, for example, at a position indicated by a virtual line in FIG. 5, and cut into a predetermined shape, as shown in FIGS. Piezoelectric element 1
It becomes 0.

When the piezoelectric element 10 is attached to the outer frame 20, the piezoelectric speaker of the present embodiment is completed.

In the piezoelectric speaker of this embodiment,
Since the damper member 40 is formed by a part of the polymer films 41 and 42 attached to the metal diaphragm 11, the thickness of the damper member 40 is uniform and determined by the thickness of the polymer films 41 and 42. Therefore, the piezoelectric speaker can flatten frequency characteristics and reduce distortion components.

Further, by directly bonding and joining the polymer films 41 and 42 to each other, the loading of the damper material 40 can be easily performed. In addition, since the polymer films 41 and 42 are laminated on the metal diaphragm 11 with the metal diaphragm 11 and the piezoelectric members 12 and 13 sandwiched from both sides, the waterproofing and moisture proofing of the piezoelectric members 12 and 13 are also ensured. Can be something. Since the polymer films 41 and 42 are thin films, it is needless to say that the polymer films 41 and 42 have good followability (adhesion) to the shape of the metal diaphragm 11.

Further, in the manufacturing method of the piezoelectric speaker according to the present embodiment, the polymer films 41 and 42 are heated and pressurized to the metal diaphragm 11 side so that the polymer films 4 and 42 are pressed.
At the same time as the laminations 1 and 42 are bonded to the metal diaphragm 11, a plurality of bending arms 32a to 32d, 34a, 34b, and 36 are provided between the diaphragm 31 and the elastic support portion 33 of the metal diaphragm 11.
Since the damper material 40 composed of a part of the polymer films 41 and 42 is loaded between the a, 36b and 37 (between the vibrating rice feed 31 and the outer frame 20), the periphery of the vibrating plate portion 31 and the bending arm portions 32a to 32b are mounted. 32d, 34a, 34b, 36a, 36b
And 37 can be surrounded by polymer films 41 and 42 having a constant thickness, respectively, and the thickness of the damper material 40 at the edge becomes uniform depending on the thickness of the polymer film.

Moreover, in this embodiment, the damper material 40 is loaded from both sides of the metal diaphragm 11 by laminating the polymer films 41 and 42 by a hot press while being transported by the provisional pressure contact rolls 201 and 202. Since the work is performed, the work can be performed very quickly, and the damper material 40 can be formed at a much higher speed and more stably as compared with a conventional film forming method such as dipping or brushing.

Further, in the above-described method of manufacturing the piezoelectric speaker, the thin film polymer films 41 and 42 can be overlapped on the metal diaphragm 11 while maintaining the thin polymer films 41 and 42 in a predetermined shape by the separators 102A and 102B.
By appropriately selecting the materials of 02A and 102B, the polymer film 41 via the separators 102A and 102B,
Reference numeral 42 denotes an outer edge portion of the diaphragm portion 31 and bending arm portions 32a to 32
d, 34a, 34b, 36a and 36b.

In the present invention, it goes without saying that the shape of the gap between the diaphragm portion and the elastic support portion of the metal diaphragm and the shapes of the plurality of bending arms can be arbitrarily set. Further, in the above-described embodiment, the elastomer film sheets are bonded to both sides of the metal diaphragm, but it is also possible to use one side. Further, although the strip films 100A and 100B with the separators are continuous strip sheets, it goes without saying that any cut shape may be used as long as the size is larger than the metal diaphragm.

[0043]

According to the present invention, it is possible to provide a piezoelectric speaker in which the thickness of the damper material can be made uniform by the thickness of the polymer film, and the frequency characteristics can be flattened and the distortion component can be reduced. Can be.

Further, according to the present invention, a piezoelectric material capable of rapidly forming and loading a damper material made of a polymer film having a constant film thickness around the diaphragm and around the bending arm of the elastic support is provided. A method for manufacturing a speaker can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing a piezoelectric speaker according to an embodiment of the present invention, wherein (a) is a front view thereof and (b) is a plan view thereof.

FIG. 2 is a front view of a piezoelectric element of the piezoelectric speaker according to the embodiment.

3A and 3B are diagrams showing a piezoelectric element of the piezoelectric speaker according to one embodiment, wherein FIG. 3A is a rear view of the piezoelectric element, and FIG. 3B is a sectional view taken along line AA of FIG.

FIG. 4 is a plan view of a metal diaphragm of the piezoelectric speaker of one embodiment.

FIG. 5 is an explanatory view of a step of laminating a metal diaphragm and a polymer film for explaining a manufacturing process of the piezoelectric speaker of one embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Piezoelectric element element 11 Metal vibrating plate 12, 13 Piezoelectric material 15 Piezoelectric vibrator 20 Outer frame 31 Vibrating plate part 31a Central part 31b Vibrating part 32a, 32b First bending arm part 32c, 32d Second bending arm part 33 Elasticity Supporting part 34 Inner frame part 34a, 34b Flexible arm part 36b Fourth flexible arm part 40 Damper material 41, 42 Thin film polymer film 100A, 100B Both belt-shaped film 100A, 100B Band-shaped film 101A, 101B Polymer film sheet 102A, 102B Separator 110 Laminated sheet portion 111A, 111B Separator winding roll 201, 202 Temporary pressure contact roll 203, 204 Main pressure contact roll

Claims (6)

[Claims] 1. A piezoelectric body, a diaphragm attached to a frame, and constituting a piezoelectric vibrator together with the piezoelectric, and the diaphragm is elastically supported by the frame via a plurality of bending arms. A metal diaphragm having an elastic supporting portion, wherein a damper member is mounted between the diaphragm portion of the metal diaphragm and the frame, wherein the damper member is provided on the metal diaphragm. A piezoelectric speaker formed of a polymer film having a predetermined thickness bonded thereto. 2. The method according to claim 1, wherein the damper member joins a polymer film disposed on both sides of the metal diaphragm between the diaphragm portion and the frame, thereby forming a gap between the diaphragm portion and the frame. The piezoelectric speaker according to claim 1, wherein the piezoelectric speaker is mounted on the piezoelectric speaker. 3. The piezoelectric speaker according to claim 2, wherein the polymer film is laminated on the metal diaphragm with the metal diaphragm and the piezoelectric body sandwiched from both sides. 4. A piezoelectric vibrator for a piezoelectric speaker, comprising: a diaphragm portion; and an elastic support portion for elastically supporting the diaphragm portion via a plurality of flexure arms. A metal diaphragm constituting a vibrator and a polymer film that can be adhered to the metal diaphragm are prepared, and the polymer film is heated and pressed in a state of being stacked on the metal diaphragm, and the metal diaphragm is prepared. A method of manufacturing a piezoelectric speaker, comprising: attaching a damper material made of the polymer film between the diaphragm portion and the elastic supporting portion of the metal diaphragm at the same time as attaching the polymer film to the metal diaphragm. . 5. A polymer film is laminated on both sides of the metal diaphragm, and both polymer films are joined between a diaphragm portion and an elastic support portion of the metal diaphragm, and the diaphragm portion and the elastic support portion are joined together. The method according to claim 4, wherein the damper material is formed between the elastic support portions. 6. A band-like film in which a separator is attached to one side of the polymer film with a lower adhesive force than the other side of the polymer film is disposed on both sides of the metal diaphragm. While laminating the polymer film on both sides of the metal diaphragm, pressing the separator of the band-shaped film from the back side of the polymer film toward the metal diaphragm, the separator after pressurizing the separator The method according to claim 5, wherein the piezoelectric speaker is separated from a laminate of a metal diaphragm and the polymer film.