JP2000324598A - Manufacture of piezoelectric speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a piezoelectric speaker which is superior in productivity and durability. SOLUTION: The piezoelectric speaker having a composite piezoelectric body sheet member formed by arraying many piezoelectric elements 14 in a sheet organic body is manufactured through an arraying state for arraying multiple piezoelectric elements in plane at specific pitch, a stage for pouring a molten organic body 16A in gaps between the arrayed piezoelectric elements, a half-setting stage for forming a half-setting sheet 52 by half-setting the poured molten organic body so that the body is still flexible, and a complete setting stage for completely setting the half-set sheet in a specific curved surface shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a speaker using a piezoelectric element, and more particularly to a method for manufacturing a piezoelectric speaker using a composite piezoelectric sheet member.

[0002]

2. Description of the Related Art Generally, a speaker causes a voice signal to flow through a voice coil connected to a voice cone, thereby causing the voice cone to vibrate mechanically due to the interaction between the current of the coil and the magnetic field of a permanent magnet. The sound is reproduced by vibrating. For sound reproduction, several tens of Hz to several tens of KH, which are human audible frequencies
Ideally, reproduction is performed efficiently and without distortion over a wide range up to z. However, in general, a single speaker cannot cover such a wide frequency range. Are used. Further, a magnet speaker using such a permanent magnet becomes large in size and heavy in order to increase sound pressure.

[0003] In recent years, there has been an increasing demand for smaller, lighter and thinner acoustic devices such as stereo devices and televisions. In response to such demands, extremely thin and lightweight piezoelectric speakers have been developed. Have been. This piezoelectric speaker uses, for example, a thin plate of lead zirconate titanate (PZT) -based ceramics. Electrodes are formed on both sides of the thin plate and attached to a metal diaphragm. The sound is reproduced by vibrating the diaphragm. However, conventional piezoelectric loudspeakers, which consist of a metal diaphragm and a piezoelectric ceramic alone, have a low degree of freedom in elasticity and are also acoustically hard. In addition, harmonics are likely to occur and distortion is likely to occur. There was a problem that it would occur.

In order to solve such a problem, the present inventor disclosed in Japanese Patent Application Laid-Open No. Hei 7-327298 that the piezoelectric effect of the piezoelectric ceramic and the We have proposed a loudspeaker using a composite piezoelectric sheet member that combines the elasticity of a speaker. A piezoelectric speaker using this composite piezoelectric sheet member forms a composite piezoelectric sheet member by embedding a large number of piezoelectric elements in an organic lattice-like sheet such as an epoxy resin, and forms electrode plates on both sides of the sheet member. The entire structure is fixed in a plate shape or a dome shape. Further, a sound quality adjusting thin film is formed on one surface of the electrode to improve the sound quality.

A conventional piezoelectric speaker previously proposed by the present applicant will be described with reference to FIGS.
FIG. 21 is an enlarged sectional view of a main part showing a general piezoelectric speaker,
FIG. 22 is an enlarged perspective view showing a composite piezoelectric sheet member used for the piezoelectric speaker shown in FIG. 21, and FIG. 23 is a sectional view showing the piezoelectric speaker. As shown in FIG.
Is a composite piezoelectric sheet member 4 composed of a piezoelectric element and an organic substance.
And two electrodes 6A and 6 uniformly bonded to both sides thereof.
B, an acoustic impedance matching holding layer 8 bonded to the surface of one of the electrodes 6A, and a holding frame 10 (see FIG. 3) made of, for example, metal or resin for holding the periphery of the laminate. ing. In the figure, reference numeral 9 denotes a protective film for preventing electrode oxidation bonded to the surface of the other electrode 6B. Then, a lead wire (not shown) is drawn from the two electrodes 6A and 6B, and an audio signal is applied to the lead wire from the audio signal source 12, whereby the composite piezoelectric sheet member 4 vibrates in the thickness direction due to the piezoelectric effect, and sound is generated. Will be emitted. In FIG. 21, each member is formed in a planar shape for the purpose of explanation, but in actuality, as shown in FIG. 23, the entire sheet is held in a curved state with the matching holding layer 8 side protruding.

In order to form the composite piezoelectric sheet member 4, first, a thickness of 0.5 m, which is uniformly polarized in the thickness direction.
m of PZT-based ceramics is fixed to a processing jig plate with a flat surface, and a 0.2 mm thick blade is used to form a grid on the surface with a groove depth of 0.3 mm and a pitch of 1.0 mm. Perform grooving. Then, an organic substance, for example, polyurethane resin, epoxy resin, silicon rubber, or the like, is filled in the lattice-shaped groove formed by this processing, and after solidifying this, the groove is applied to the processing jig plate surface and processed. Grinding is removed until a lattice surface appears. FIG. 22 is a perspective view of the composite piezoelectric sheet member 4 thus formed. In the figure, a hatched portion having a prismatic shape indicates a piezoelectric element 14, and a lattice portion connecting the piezoelectric element 14 indicates an organic substance 16. Here, the volume ratio of the piezoelectric elements in the composite piezoelectric sheet member 4 can be changed by appropriately selecting the thickness of the blade and the groove pitch during processing. Further, by selecting the material (hardness) of the organic material used in the composite piezoelectric sheet member 4, the degree of the shape holding function of the matching holding layer 8 is increased or decreased.

The electrodes 6A and 6B are made of an aluminum film or a Cr-Au film. The acoustic impedance matching holding layer 8 has a matching function for properly transmitting the vibration of the piezoelectric sheet member 4 to the air vibration, and a shape holding function for holding the bending state of the very flexible piezoelectric sheet 4. It also has an antioxidant function for preventing oxidation of the electrode 6A stretched inside, and is formed of, for example, polyurethane resin. By selecting the thickness, material, hardness and the like of the matching holding layer 8, an optimum frequency characteristic at the time of reproduction is obtained.

As the protective film 9, a relatively soft and very thin organic material, for example, a polyurethane resin is used. In this case, the thickness of the matching holding layer 8 may be reduced, and the thickness of the protective layer 9 may be increased accordingly. In any case, the curved shape of the sheet is held by the matching holding layer 8 and the protective layer 9 as a whole. I do. Here, as a representative example of the thickness of each member, for example, the thickness L1 of the piezoelectric sheet member 4 is set to 0.1.
2 mm, the thickness L2 of both electrodes 6A and 6B is 0.3 μm, and the thickness L3 of the acoustic impedance matching holding layer 8 is 3.
0 mm, and the thickness L4 of the protective film 9 is about 0.1 mm.

[0009]

By the way, when the composite piezoelectric sheet member 4 is manufactured by the above-described method, the organic material 16 made of resin is completely cured and then deformed into a predetermined curved shape. Therefore, the deformation processing is considerably difficult due to the rigidity of the composite piezoelectric sheet member 4, and in the worst case, the sheet member 4 may be damaged. Further, it is quite difficult to fill the small gap between the piezoelectric elements 14 with the organic substance 16, and there are also cases where air bubbles are trapped inside the gap, thereby lowering durability and acoustic characteristics. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a method for manufacturing a piezoelectric speaker having excellent productivity and durability.

[0010]

The invention defined in claim 1 is a method of manufacturing a piezoelectric speaker having a composite piezoelectric sheet member in which a large number of piezoelectric elements are arranged in a sheet-like organic substance. An arranging step of arranging the piezoelectric elements in a plane at a predetermined pitch, an organic distribution step of pouring the molten organic substance into the gaps between the arranged piezoelectric elements, and a step in which the poured molten organic substance remains flexible. A semi-curing step of semi-curing to form a semi-cured sheet, and a complete curing step of completely curing the semi-cured sheet while maintaining the semi-cured sheet in a predetermined curved shape.

Accordingly, the composite piezoelectric sheet member is formed into a curved surface in a semi-cured state with the molten organic material filled in the gaps between the piezoelectric elements, so that a large stress is not applied at the time of molding, and the composite piezoelectric sheet member can be easily formed. In addition, it can be manufactured with good mass productivity. As defined in claim 2, by performing a degassing step of degassing the gap between the piezoelectric elements under reduced pressure atmosphere between the arranging step and the organic distribution step, bubbles are generated in the gap. Without getting in,
The molten organic material can be sufficiently poured, and thus the bonding between the piezoelectric element and the organic material is strengthened, so that the durability and acoustic characteristics can be improved.

According to a third aspect of the present invention, in the arranging step, the piezoelectric elements are arranged on and adhered to the adhesive film using a mesh-shaped arranging mask. This makes it possible to easily arrange the piezoelectric elements on the adhesive film in a short time, so that mass productivity can be further improved.

[0013] As defined in claim 4, the arranging step comprises: arranging and bonding a piezoelectric element plate having a shape larger than the piezoelectric element on a preliminary adhesive film; A groove forming step of forming a cutting groove at a predetermined pitch; a dividing step of dividing the piezoelectric element plate by pulling the preliminary adhesive film in a plane to form a large number of piezoelectric elements; A transferring step of transferring the piezoelectric element from the adhesive film using an adhesive film. According to this, since a cutting groove is formed on a piezoelectric element plate having a large area and then divided, the formation and the arrangement of the piezoelectric element having a small area are performed at the same time. Can be further improved.

According to a fifth aspect of the present invention, the molten organic substance used in the resin pouring step is produced by performing a defoaming treatment for removing bubbles contained by mixing a plurality of undiluted organic substances. According to this, air bubbles mixed in the molten organic substance itself can also be removed, so that durability and acoustic characteristics can be improved.

According to a sixth aspect of the present invention, in the semi-curing step, pressure is applied and heating is performed in a state in which a molten organic substance is poured into the gaps between the piezoelectric elements, thereby performing heating.
Excess molten organic matter can be eliminated, and the curing speed can be accelerated, so that mass productivity can be further improved.

[0016] In the complete curing step, the semi-cured sheet may be heated. According to this, the curing speed can be accelerated by heating, and the mass productivity can be further improved.

The invention defined in claim 8 is a method of manufacturing a piezoelectric speaker having a composite piezoelectric sheet member in which a large number of piezoelectric elements are arranged in a sheet-like organic substance, wherein the plurality of piezoelectric elements are planarly arranged. An arraying step of arranging, the transferring step of transferring the piezoelectric elements to a forming base material having a curved surface shape to be finally formed, and the forming base material,
An organic substance injecting step of injecting a molten organic substance into a gap between the piezoelectric elements while being fitted in a molding die that forms a pair with this;
And an injection organic substance complete curing step of completely curing the injected molten organic substance. According to this, since the previously required semi-curing step can be omitted, the number of steps is reduced correspondingly, and the mass productivity can be further improved.

According to a ninth aspect of the present invention, the step of injecting the organic substance includes a degassing step of degassing the gap under a reduced pressure atmosphere before injecting the molten organic substance into the gap. As in the case of the above-mentioned claim 2, it is possible to sufficiently pour the molten organic substance without air bubbles entering the gap, so that the bonding between the piezoelectric element and the organic substance is strengthened, and the durability and acoustic properties are improved. The characteristics can be improved.

According to a tenth aspect of the present invention, in the arranging step, the piezoelectric elements are arranged on and adhered to the adhesive film using a mesh-shaped arranging mask. According to this, the piezoelectric elements can be easily arranged on the pressure-sensitive adhesive film in a short time in the same manner as in the case of the third aspect, so that mass productivity can be further improved.

[0020] The arranging step may include arranging and adhering a piezoelectric element plate having a shape larger than the piezoelectric element on a preliminary adhesive film, and attaching the piezoelectric element plate to the piezoelectric element plate. A groove forming step of forming a cutting groove at a predetermined pitch; a dividing step of dividing the piezoelectric element plate by pulling the preliminary adhesive film in a plane to form a large number of piezoelectric elements; A transferring step of transferring the piezoelectric element from the adhesive film using an adhesive film. According to this, similarly to the case of the above-mentioned claim 4, after forming a cutting groove in a piezoelectric element plate having a large area, and then dividing it, formation of a piezoelectric element having a small area and its arrangement are performed simultaneously. Therefore, the production becomes simple, and the mass productivity can be further improved.

According to a twelfth aspect of the present invention, the molten organic material used in the resin pouring step is produced by performing a defoaming treatment for removing a bubble contained by mixing a plurality of organic stock solutions. According to this, similarly to the case of the above-mentioned claim 5, since bubbles mixed in the molten organic substance itself can be removed, it is possible to improve durability and acoustic characteristics.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a piezoelectric speaker according to the present invention will be described below in detail with reference to the accompanying drawings. First, the first method invention will be described. FIG. 1 is a perspective view showing an arrangement process when a piezoelectric element is arranged on an adhesive film, FIG. 2 is a perspective view showing a state in which a piezoelectric element is arranged on an adhesive film, and FIG. 3 is a side view of a member shown in FIG. FIG. 4 is a view showing a state in which the arranged piezoelectric elements are accommodated in a fixing jig. FIG. 5 is a view for explaining a degassing step. FIG. 6 is a view for explaining an organic distribution step. FIGS. 8A, 8B, 9A, and 9B are diagrams for explaining a semi-curing process, FIGS. 8A and 8B are diagrams for explaining a complete curing process, and FIGS. The same members as those used in FIGS. 21 to 23 are denoted by the same reference numerals and described. The overall configuration of the piezoelectric speaker is shown in FIGS.
Therefore, the process of manufacturing the composite piezoelectric sheet member will be mainly described here. The method of manufacturing the composite piezoelectric sheet member mainly includes an arrangement step, an organic distribution step, a semi-curing step, and a complete curing step.

As shown in FIG. 1, reference numeral 14 denotes a substantially rectangular parallelepiped piezoelectric element made of a PZT ceramic or the like and having a piezoelectric effect, and has a thickness L5 of about 0.2 mm. The length of L7 is about 2 mm. At this point, the piezoelectric element 14 has not yet been subjected to the polarization processing. First, the arrangement process will be described. A large number of the piezoelectric elements 14 are arranged vertically and horizontally at a predetermined pitch P1 on an adhesive film 18 such as an acrylic film having an adhesive applied to the surface (see FIGS. 2 and 3). ).
The pitch P1 is, for example, about 2.2 mm. Therefore, the width L8 of the gap 19 between the adjacent piezoelectric elements 14 is equal to 0.1 mm.
It is about 2 mm. In this case, since the size of each piezoelectric element 14 is very small, as shown in FIG.
0 is used. For example, a stainless steel metal plate can be used as the arrangement mask 20. The arrangement mask 20 has a size larger than the plane size (2 mm square) of the piezoelectric element 14.
A large number of slightly larger drop-in holes 22 are formed vertically and horizontally at a predetermined pitch, and the piezoelectric element 14 can be dropped through the drop-in holes 22.
Specifically, the piezoelectric element 14 is dropped from each of the recesses 22 of the array mask 20 in a state where the adhesive film 18 and the array mask 20 are overlaid and adhered. Then, the piezoelectric elements 14 are adhered on the adhesive film 18 and the arrangement mask 20 is removed. As a result, as shown in FIGS. 2 and 3, the piezoelectric elements 14 are arranged on the adhesive film 18 in a plane, and the arrangement step is completed.

Next, as shown in FIG. 4, the adhesive film 18 on which the piezoelectric elements 14 are arranged is placed on a surface plate 24, and in this state, the surface plate 24 is fixed to the fixing frame 2 of the positioning jig 26.
8 and set. At this time, since the molten organic matter (resin) protrudes as described later, a protective sheet 30 such as a vinyl sheet is laid on the upper surface of the positioning jig 26 so that the resin does not adhere to the jig side. Also, it is preferable to apply fluorine grease on the upper surface of the surface plate 24 so that the adhesive film 18 can be easily peeled off.
Then, the positioning jig 26 accommodating the platen 24 with the adhesive film is accommodated in a vacuum container 32 which can be evacuated as shown in FIG. A gate door 34 that can be opened and closed is provided on the side wall of the vacuum vessel 32, and the positioning jig 26 is loaded and unloaded through the gate door 34.

Next, a vacuum pump (not shown) is driven to depressurize the interior of the vacuum vessel 32 and evacuate it, thereby performing a deaeration step. That is, the inside of the vacuum container 32 is, for example, 1
By evacuating to about mmTorr, air in the gap 19 between the adjacent piezoelectric elements 14 is exhausted and deaerated. At this time, as the degree of vacuum is higher, the efficiency of degassing is improved, and it is possible to prevent bubbles from being included in the gap 19 when the next molten organic material is poured. Note that this deaeration step may be performed as needed, and when this deaeration treatment is not performed,
It is not necessary to use the vacuum container 32. After the deaeration step is completed, the process proceeds to an organic distribution step. A swivel arm 36 that is rotatable and retractable is attached to the side wall of the vacuum vessel 32. A cup 38 containing molten organic matter 16A therein is attached to the tip of the arm 36.
Is held. As the molten organic material 16A, a two-liquid mixture type organic material, specifically, a resin material, is used, and the two resin materials consisting of the main material and the hardening material are mixed and stirred to gradually cure. have. In this case, air bubbles are mixed in the molten resin (organic substance) 16A when the resin raw material is stirred. Therefore, the molten resin 16A is allowed to stand in advance in, for example, the vacuum container 32 under a reduced pressure atmosphere for about 10 to 30 minutes. To remove air bubbles and perform a defoaming treatment.

Then, the revolving arm 36 is driven, and FIG.
By inverting the cup 38 as shown in (2), the defoamed molten resin 16A flows down onto the piezoelectric elements 14 arranged as described above. This allows
The molten resin 16 </ b> A spreads in the plane direction and flows into the gaps 19 between the piezoelectric elements 14. in this case,
It is preferable that the swivel arm 36 is moved up and down so that the molten resin 16A flows down uniformly over the entire area of the large number of piezoelectric elements 14. Here, since the degassing process and the defoaming process are performed as described above, no air bubbles or air pockets enter the gap 19, and only the molten resin 16A can be poured purely. As the molten resin 16A, for example, Ecobond 45LV (trade name) having an unmixed viscosity of about 35,000 CPS can be used. When the pouring step is completed in this way, the process proceeds to the semi-curing step.

As shown in FIG. 7, a pressure piston 40 is provided on the ceiling of the vacuum vessel 32 so as to be capable of expanding and contracting downward. For example, the pressing piston 40 is provided on the piezoelectric element 14 into which the molten resin 16A has been poured. Silicon rubber 4 about 1 mm thick
The push plate 44 is placed via the second plate 2. Then, the pressing piston 40 is driven to press down the pressing plate 44 at a predetermined pressure to apply pressure. Then, the molten resin 16A is semi-cured by being left in this pressure applied state for a predetermined time. At this time, the excess molten resin 16B protrudes outside from the peripheral portion and is removed. The reaction rate of the molten resin 16A is almost completely cured by leaving it at room temperature for 24 hours, so that it becomes a semi-cured state by leaving it at room temperature for about 8 hours. If the temperature is high, the molten resin 16
Since the reaction speed of A is improved, for example, the positioning jig 26
By heating with the heater 46 provided in the above, the time required for the semi-curing can be shortened and rapid processing can be performed. For example, if the molten resin 16A is heated to about 40 ° C., it can be sufficiently semi-cured in about 2 hours. Further, if it is heated to about 100 ° C., it will be in a semi-cured state in about 10 minutes. The heating temperature depends on the molten resin to be used, but is about 100 ° C. at the maximum in consideration of deterioration of the material. In addition, the semi-cured state means that the piezoelectric element 14 has a degree of curing that does not fall off at least from the resin, and has sufficient flexibility that the formed semi-cured sheet can be easily deformed. It refers to the range up to such a degree of curing.

If grease or the like is applied to the lower surface of the pressing plate 44 or the upper surface of the silicon rubber 42, pressure can be applied uniformly in the surface of the silicon rubber 42 by the flow action of the grease. The in-plane uniformity of the thickness of the semi-cured sheet can be improved. When the semi-curing process is completed in this way, the process proceeds to a complete curing process. As described above, the semi-cured sheet in the semi-cured state is taken out of the vacuum container 32 together with the positioning jig 26, and the platen 24, the pressing plate 44, the silicone rubber 42 and the adhesive film 18 are removed, and the semi-cured sheet is removed. Use as a single unit. As shown in FIG. 8, an extra portion of the outer peripheral portion of the semi-cured sheet 52 is cut, and the semi-cured sheet 52 is mounted along a forming surface of a concave forming jig 50 having a curved surface shape to be formed. In this case, since the semi-cured sheet 52 is very flexible,
It can be easily mounted along the curved forming surface.

Then, in this state, a predetermined pressure is applied to the semi-cured sheet 52 by fitting a convex-shaped forming jig 54 which is paired with the concave-shaped forming jig 50 as shown in FIG. The semi-cured resin in the sheet is completely cured. In this case, if left at room temperature, depending on the resin material used, it takes, for example, about 16 hours to complete curing. However, the heater 56 incorporated in the concave forming jig 50 is driven to drive the semi-cured sheet 52 to, for example, 40 hours. If the heating is maintained at about ℃, it is possible to complete the curing in about 2 hours, for example. By thus completely curing the semi-cured sheet 52, a composite piezoelectric sheet member 4 having a desired curved surface shape as shown in FIGS. 10 and 22 is completed. Thereafter, fog of the resin adhering to the surface of the completed composite piezoelectric sheet member 4 is removed by a file or the like, and then, as shown in FIG. 21, the electrodes 6A and 6B, the acoustic impedance matching holding layer 8 and the protective film 9 are removed. Formed and then both electrodes 6
A piezoelectric speaker is completed by applying a DC voltage to A and 6B to polarize the piezoelectric element 14. The area occupied by the piezoelectric element 14 with respect to the entire area of the composite piezoelectric sheet member 4 is preferably in the range of 60 to 90% from the viewpoint of the characteristic efficiency.

As described above, according to the first method of the present invention, the composite piezoelectric sheet member 4 is maintained in a predetermined curved shape while being fully cured in a semi-cured state and is completely flexible. It is hardened to make it a final rigid curved surface, so it is easy to manufacture and rich in productivity, and it does not apply excessive stress, so there is no damage and it is possible to improve durability . In this embodiment, the cross-sectional shape of the piezoelectric element 14 is substantially square, but is not limited thereto, and may be rectangular, elliptical, circular, or the like. In this case, array mask 2
Of course, the shape of the 0 drop-in hole 22 is also made to correspond to it. In particular, when the cross-sectional shape of the piezoelectric element 14 is circular, there is no limitation on the direction of the piezoelectric element 14, so that the arrangement on the adhesive film 18 using the arrangement mask 20 can be performed more quickly. .

In the arrangement step of the above embodiment, the piezoelectric elements 14 formed in advance are arranged on the adhesive film 18 by using the arrangement mask 20, but the invention is not limited to this. A small piezoelectric element 1 is formed by using a relatively large piezoelectric element plate before forming a single unit.
4 may be arranged. FIG. 11 to FIG. 15 are explanatory diagrams for explaining such modified examples of the arrangement process. This arrangement step includes an element plate arrangement step, a groove formation step, a division step, and a transfer step. First, as shown in FIG. 11, a plurality of piezoelectric element plates 62 having a relatively large area are placed on a pre-adhesive film 60 having an adhesive surface as shown in FIG.
They are arranged and adhered at a distance of about 05 mm.
In the illustrated example, the piezoelectric element plate 62 has such a size that, for example, 36 small piezoelectric elements 14 can be formed, but is actually a square of 2 to 3 cm square.

After the element plate arranging step is completed in this way, the process proceeds to a groove forming step. In this groove forming step, as shown in FIG. 12, a cutting groove 66 is formed on each of the piezoelectric element plates 62 arranged as described above at a predetermined pitch in the vertical direction and the horizontal direction using a dicing saw 64 in the depth direction. Formed part way. This cutting groove 66
Is set to the size of one piezoelectric element. FIG. 13 is an enlarged side view of the piezoelectric element plate 62 in which such a cutting groove 66 is formed. After the completion of the groove forming step, the process proceeds to the dividing step. When the cutting grooves 66 are formed in the respective piezoelectric element plates 62 as described above, as shown in FIG. 14, the preliminary adhesive film 60 is pulled so as to extend in the vertical and horizontal directions in a plane, whereby the respective piezoelectric element plates 62 Since the strength of the portion of the cutting groove 66 formed in this is low, cracks occur along the cutting groove 66 and the piezoelectric element 14 is divided into many.

After the division step is completed in this way, the process proceeds to the transfer step. In this transfer step, if the piezoelectric elements 14 are formed by dividing each of the piezoelectric element plates 62 as described above, the preliminary adhesive film 60 is pulled so that the gap 9 between the adjacent piezoelectric elements 14 has a predetermined width L8. While maintaining the above, each piezoelectric element 14 is transferred using an adhesive film 18 separately prepared as shown in FIG. FIG. 15 shows the state at the time of transfer.
Thereby, the piezoelectric elements 14 can be arranged on the adhesive film 18 in substantially the same form as shown in FIGS. In this case, by forming the cutting grooves 66 using the dicing saw 64 or the like, a large number of piezoelectric elements 14 can be formed at a time and can be arranged at the same time, so that the piezoelectric speaker can be manufactured more quickly. And productivity can be further improved. In each of the above-described embodiments, the organic material (resin) in the composite piezoelectric sheet member 4 is semi-cured and the curved surface is formed and completely cured. However, the semi-curing step of semi-curing the molten organic material is performed. Alternatively, a desired curved surface shape may be directly formed without going through. FIG. 16 to FIG. 19 are explanatory diagrams for explaining such a second method invention.

The second method invention includes an arrangement step, a transfer step, an organic substance injection step, and an injection organic substance complete curing step. First, the arrangement step is performed in exactly the same manner as described in the first method invention, and in the next transfer step, the piezoelectric elements 14 arranged on the adhesive film as shown in FIGS. Is pressed by the molding base material 70 and transferred to this surface. The molding base material 70 is made of an elastic member such as silicon rubber, for example.
For example, it has a dome shape. Accordingly, when the molded member 70 is pushed down onto the piezoelectric element 14 as shown in FIG. 17, the molded member 70 is sufficiently deformed. The surface of the molding base material 70 is also coated with an adhesive substance, and
When 0 is raised again, the piezoelectric element 14 is in a state of being sucked and transferred to the surface of the molding base material 70 as shown in FIG.

After the transfer step has been completed in this way, the process proceeds to the organic substance injection step. As shown in FIG. 19, in this organic substance injecting step, a molding base material 70 with the piezoelectric element 14 attached to the surface is fitted into a concave molding die 72 that is paired with the molding base material 70, and in this state, the molten resin (organic substance) 16 is formed.
A is introduced, and the molten resin 16A is poured into the gap between the piezoelectric elements 14 by an injection molding method or the like.
In this case, a ring-shaped runner 7 is formed around the upper side of the forming base material 70.
The molten resin 16A flows into the gap between the piezoelectric elements from the entire circumference of the runner 74. At this time, an exhaust passage 76 is formed in the molding die 72 so as to communicate with a substantially lowermost portion of the molding surface, and is evacuated at the same time as the molten resin 16A is poured in or by a vacuum pump or the like (not shown). Thus, the atmosphere in the gap between the piezoelectric elements is evacuated, that is, degassed to promote the flow of the molten resin 16A. The molten resin 16A used here is, of course, preliminarily subjected to the defoaming treatment as described above. In particular, since the molten resin 16A needs to flow through a narrow gap, the molten resin 16A used has a viscosity. The lower the better, the viscosity at 23 ° C is 9
A transparent low-viscosity epoxy resin of about 100 to 1000 CPS,
For example, Crystal Resin (trade name) manufactured by Kokusai Chemical Co., Ltd. can be used.

When the organic substance injection step has been completed in this way, the process proceeds to the injection organic substance complete curing step. In this step, while the injection of the molten resin 16A shown in FIG. 19 is stopped, the molding die 72 and the molding base material 70 are left as they are for a predetermined time, and the molten resin 16A is completely cured. In this case, if the heater 78 incorporated in the molding die 72 is driven and heated to, for example, about 40 ° C. to 80 ° C., the reaction for curing the resin is accelerated accordingly, and the time required for complete curing is reduced. It is possible to shorten and improve the productivity. As described above, according to the second method invention, the semi-curing step required in the first method invention can be omitted, and accordingly, the manufacturing time is shortened and the productivity is improved. It becomes possible.

FIG. 20 is a graph showing the frequency-output characteristics of the headphones produced by the method of the present invention.
Output is sufficient over a wide range of 30 KHz,
It turned out that it showed good characteristics. The specifications of this headphone are as follows: the diameter is 80 mm, the radius of curvature of the dome-shaped speaker is 50 mm, the diameter of the piezoelectric element is 2 mm, and the area ratio of the piezoelectric element is 70%. is there. The piezoelectric speaker manufactured by the method of the present invention can be used for a headphone, a tweeter, a hearing aid, a telephone, and the like, in addition to a speaker for an ordinary audio or the like. It should be noted that the dimensions, shapes, and the like of each member described in the present embodiment are merely examples, and are not limited thereto.

[0038]

As described above, according to the method for manufacturing a piezoelectric speaker of the present invention, the following excellent functions and effects can be exhibited. According to the invention as defined in claim 1, the molten organic material is formed into a curved surface in a semi-cured state, and is completely cured in this state. It can be manufactured with good mass productivity. According to the second aspect of the present invention, it is possible to sufficiently flow the molten organic substance without air bubbles entering into the gap between the piezoelectric elements, and therefore, the bonding between the piezoelectric element and the organic substance is strengthened and the durability is improved. In addition, the acoustic characteristics can be improved. According to the third aspect of the present invention, since the piezoelectric elements can be easily arranged on the adhesive film in a short time, mass productivity can be further improved. According to the fourth aspect of the present invention, the cutting groove is formed on the piezoelectric element plate having a large area and then divided, thereby simultaneously forming the piezoelectric element having a small area and arranging the same. Thus, mass productivity can be further improved. According to the fifth aspect of the present invention, since bubbles mixed in the molten organic substance itself can be removed, it is possible to improve durability and acoustic characteristics. According to the invention of claim 6, by applying pressure and heating while the molten organic substance is poured into the gap between the piezoelectric elements, it is possible to eliminate excess molten organic substance and to accelerate the curing rate. Thus, mass productivity can be further improved. According to the invention of claim 7, if the semi-cured sheet is heated, the curing speed can be accelerated by heating, and the mass productivity can be further improved. According to the invention of claim 8, since the previously required semi-curing step can be omitted,
To that extent, the number of steps is reduced, and mass productivity can be further improved. According to the ninth aspect of the present invention, the second aspect of the present invention is provided.
As in the case of, no bubbles enter the gap,
The molten organic material can be sufficiently poured, and thus the bonding between the piezoelectric element and the organic material is strengthened, so that the durability and acoustic characteristics can be improved. According to the tenth aspect, as in the case of the third aspect, since the piezoelectric elements can be easily and quickly arranged on the adhesive film in a short time, mass productivity can be further improved. Becomes According to the eleventh aspect, similarly to the case of the fourth aspect, after forming a cutting groove in a piezoelectric element plate having a large area and dividing the same, the formation of a piezoelectric element having a small area and the arrangement thereof can be performed. Since the processes are performed at the same time, the manufacturing is simplified, and the mass productivity can be further improved. According to the twelfth aspect, as in the case of the fifth aspect, bubbles mixed in the molten organic substance itself can be removed, so that it is possible to improve durability and acoustic characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an arrangement process when arranging a piezoelectric element on an adhesive film.

FIG. 2 is a perspective view showing a state where a piezoelectric element is arranged on an adhesive film.

FIG. 3 is a side view of the member shown in FIG. 2;

FIG. 4 is a diagram showing a state in which the arranged piezoelectric elements are housed in a fixing jig.

FIG. 5 is a view for explaining a deaeration step.

FIG. 6 is a diagram for explaining an organic distribution process.

FIG. 7 is a view for explaining a semi-curing step.

FIG. 8 is a view for explaining a complete curing step.

FIG. 9 is a view for explaining a complete curing step.

FIG. 10 is a view showing a composite piezoelectric sheet member formed into a curved surface.

FIG. 11 is an explanatory diagram for explaining a modification of the arrangement step.

FIG. 12 is an explanatory diagram for explaining a modification of the arrangement step.

FIG. 13 is an explanatory diagram for describing a modification of the arrangement step.

FIG. 14 is an explanatory diagram for explaining a modification of the arrangement step.

FIG. 15 is an explanatory diagram for explaining a modification of the arrangement step.

FIG. 16 is an explanatory diagram for explaining the second method invention.

FIG. 17 is an explanatory diagram for explaining the second method invention.

FIG. 18 is an explanatory diagram for explaining the second method invention.

FIG. 19 is an explanatory diagram for explaining the second method invention.

FIG. 20 shows the frequency of headphones produced by the method of the present invention.
4 is a graph showing output characteristics.

FIG. 21 is an enlarged sectional view of a main part showing a general piezoelectric speaker.

22 is an enlarged perspective view showing a composite piezoelectric sheet member used for the piezoelectric speaker shown in FIG. 21.

FIG. 23 is a sectional view showing a piezoelectric speaker.

[Explanation of symbols]

 Reference Signs List 2 piezoelectric speaker 4 composite piezoelectric sheet member 6A, 6B electrode 14 piezoelectric element 16 organic substance 16A molten organic substance (resin) 18 adhesive film 19 gap 20 array mask 22 drop-in hole 32 vacuum container 40 pressing piston 52 semi-cured sheet 60 preliminary adhesive film 62 Piezoelectric element plate 66 Cutting groove 70 Molding base material 72 Molding die

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenji Akihama 5200 Sankajiri, Kumagaya-shi, Saitama Hitachi Metals, Ltd. Magnetic Materials Research Laboratories (72) Inventor Tadashi Furuya 5200 Sangajiri, Kumagaya-shi, Saitama Hitachi, Ltd. Within Materials Research Laboratory (72) Inventor Chitose Nakatani 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in Hitachi Advanced Systems, Ltd. (reference) 5D004 AA02 AA07 BB01 CC04 CC06 CC10 DD02 EE00 GG00

Claims (12)

[Claims] 1. A method of manufacturing a piezoelectric speaker having a composite piezoelectric sheet member in which a large number of piezoelectric elements are arranged in a sheet-like organic material, wherein the plurality of piezoelectric elements are arranged in a plane at a predetermined pitch. A step, an organic distribution step of flowing molten organic matter into the gaps between the arrayed piezoelectric elements, and a semi-curing step of semi-curing the poured molten organic substance to the extent that the flexibility remains to produce a semi-cured sheet. A complete curing step of completely curing the semi-cured sheet while maintaining the semi-cured sheet in a predetermined curved shape. 2. The piezoelectric speaker according to claim 1, wherein a deaeration step of deaeration of a gap between the piezoelectric elements is performed under a reduced pressure atmosphere between the arrangement step and the organic distribution step. Manufacturing method. 3. The method for manufacturing a piezoelectric speaker according to claim 1, wherein in the arranging step, the piezoelectric elements are arranged and adhered on an adhesive film using a mesh-shaped arrangement mask. 4. The arranging step includes: arranging a piezoelectric element plate having a shape larger than the piezoelectric element on a preliminary adhesive film and adhering the same; and forming cutting grooves at a predetermined pitch on the piezoelectric element plate. Forming a groove, forming a plurality of piezoelectric elements by dividing the piezoelectric element plate by planarly pulling the preliminary adhesive film, and dividing the piezoelectric element from the preliminary adhesive film in the tension state. 3. The method of manufacturing a piezoelectric speaker according to claim 1, further comprising: a transfer step of transferring by an adhesive film. 5. The method according to claim 1, wherein the molten organic material used in the resin pouring step is prepared by performing a defoaming treatment for removing bubbles contained by mixing a plurality of organic material stock solutions. A method for manufacturing a piezoelectric speaker according to any one of claims 1 to 3. 6. The piezoelectric speaker according to claim 1, wherein in the semi-curing step, pressure is applied and heating is performed in a state in which a molten organic substance is poured into the gap between the piezoelectric elements. Manufacturing method. 7. The method according to claim 1, wherein the semi-cured sheet is heated in the completely curing step. 8. A method of manufacturing a piezoelectric speaker having a composite piezoelectric sheet member in which a large number of piezoelectric elements are arranged in a sheet-like organic substance, wherein: an arrangement step of arranging the plurality of piezoelectric elements in a plane. A transferring step of transferring the piezoelectric element to a forming base material having a curved surface shape to be finally formed, and the piezoelectric element in a state where the forming base material is fitted in a forming die paired with the forming step. A method of manufacturing a piezoelectric speaker, comprising: an organic substance injecting step of injecting a molten organic substance into a gap therebetween; and an injected organic substance complete curing step of completely curing the injected molten organic substance. 9. The piezoelectric device according to claim 8, wherein the step of injecting the organic substance includes a step of degassing the gap under a reduced pressure atmosphere before injecting the molten organic substance into the gap. A method for manufacturing a speaker. 10. In the arranging step, the piezoelectric element is
10. The method for manufacturing a piezoelectric speaker according to claim 8, wherein the piezoelectric speaker is arranged and adhered on an adhesive film using a mesh-shaped arrangement mask. 11. The arranging step includes: arranging a piezoelectric element plate having a shape larger than that of the piezoelectric element on a preliminary adhesive film and adhering the same; and forming a cutting groove on the piezoelectric element plate at a predetermined pitch. Forming a groove, forming a plurality of piezoelectric elements by dividing the piezoelectric element plate by planarly pulling the preliminary adhesive film, and dividing the piezoelectric element from the preliminary adhesive film in the tension state. 10. The method for manufacturing a piezoelectric speaker according to claim 8, further comprising: a transfer step of transferring by a pressure-sensitive adhesive film. 12. The method according to claim 8, wherein the molten organic substance used in the resin pouring step is prepared by performing a defoaming treatment for removing bubbles contained by mixing a plurality of organic substance stock solutions. A method for manufacturing a piezoelectric speaker according to any one of claims 1 to 3.