JP2015126500A - Piezoelectric acoustic element and piezoelectric loudspeaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric acoustic element and a piezoelectric loudspeaker that utilize a piezoelectric element, that are small in size, light in weight, thin, and low in power consumption, and that have good sound pressure characteristics.SOLUTION: A piezoelectric loudspeaker 60 comprises a piezoelectric acoustic element 10 in a housing 62. In the piezoelectric acoustic element 10, a plurality of piezoelectric elements 20-50 are arranged in a matrix on one principal surface 12A of a supporting body 12 with flexibility. A deformation amount of the supporting body 12 is increased while suppressing a deformation amount of the piezoelectric elements 20-50 by deformation of a supporting body part among the piezoelectric elements 20-50. The piezoelectric elements 20-50 are a bimorph type and are polarized so as to be displaced in a lamination direction at the same phase. Substantially cross-shaped wiring is provided among the piezoelectric elements 20-50, and wiring is provided around the piezoelectric elements 20-50, and the rigidity is increased to stabilize the displacement and the sound quality. The circumferential edge of the piezoelectric acoustic element 10 is pressed by a metal frame 80 and a resin frame 82, and thereby, the piezoelectric acoustic element 10 is supported by the housing 62.

Description

  The present invention relates to a piezoelectric acoustic element and a piezoelectric speaker using a piezoelectric element, and more specifically to improvement of mid-range sound pressure characteristics.

  A dynamic speaker generally used as an electromagnetic speaker is strongly affected by a back air chamber, and has disadvantages such as an increase in power consumption, a tendency to be thick, and a large influence of magnetism. On the other hand, a piezoelectric speaker has been developed that uses a piezoelectric element as an acoustic element to reduce the size, thickness, weight, and the like. For example, in Patent Document 1 below, in a piezoelectric speaker having a metal diaphragm, a piezoelectric body, and a frame body, the metal diaphragm includes a diaphragm portion in which the piezoelectric body is bonded to both surfaces to form a piezoelectric vibrator, Disclosed is a frame body attachment portion attached to the frame body, and a plurality of flexure arm portions that elastically support the diaphragm portion and the frame body attachment portion via a plurality of slit-shaped holes. ing. Patent Document 2 listed below includes a plurality of piezoelectric vibrators that have a piezoelectric element and an elastic member and output modulated ultrasonic waves that are demodulated to an audible sound due to a density phenomenon in the air, and a plurality of the piezoelectric elements. There is disclosed an oscillation device having a support body in which vibrators are arranged in a plurality of stages in the vertical direction and the piezoelectric vibrators of each stage are arranged in a planar shape so as to overlap each other.

JP 2006-287968 A JP 2012-100054 A

  By the way, the technique described in Patent Document 1 has a structure in which a piezoelectric body is bonded to a metal diaphragm. For this reason, when the ceramic piezoelectric element is enlarged and the deformation amount of the piezoelectric element is increased in order to increase the sound pressure, there is a possibility that a crack is generated in the ceramic piezoelectric element. In the technique described in Patent Document 2, since a plurality of piezoelectric elements are arranged in the height direction, variations in the ceramic piezoelectric elements and differences in the height direction occur in individual ceramic piezoelectric elements. Sound may interfere with the sound quality.

  The present invention focuses on the above points, and provides a piezoelectric acoustic element and a piezoelectric speaker that use a piezoelectric element and are small, light, thin, and have low power consumption and good sound pressure characteristics. Is the purpose.

  The piezoelectric acoustic element of the present invention is characterized in that a plurality of piezoelectric elements are arranged in a matrix on one main surface of a flexible support. One of the main forms is characterized in that a resin layer is formed around the plurality of piezoelectric elements. Another embodiment is characterized in that metal wires connecting the plurality of piezoelectric elements are wired between the plurality of piezoelectric elements and around the plurality of piezoelectric elements. Yet another embodiment is characterized in that the number of the piezoelectric elements is four and the metal wires wired between the piezoelectric elements are substantially cross-shaped. Yet another embodiment is characterized in that the piezoelectric element is a bimorph type, and the piezoelectric element has a polarization direction different from that of another piezoelectric element adjacent on the support.

  A piezoelectric speaker according to the present invention has one of the piezoelectric acoustic elements and a casing that supports the outer periphery of the piezoelectric acoustic element and has a sound emitting hole on a main surface side of a support on which the piezoelectric element is not disposed. And a frame body that is disposed between the main surface of the support on the side where the piezoelectric element is disposed and the lid portion of the housing, and presses the outer periphery of the piezoelectric acoustic element against the housing. It is characterized by having. One of the main forms is that the frame is made of a metal frame disposed on the piezoelectric acoustic element side, and a resin frame disposed between the metal frame and the lid of the housing. It is characterized by comprising. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  According to the present invention, by arranging a plurality of piezoelectric elements in a matrix on one main surface of a flexible support, deformation of the piezoelectric elements is caused by deformation of the support portion between the plurality of piezoelectric elements. The amount of deformation of the support was increased while the amount was suppressed. For this reason, a sound pressure acoustic element and a piezoelectric speaker with high sound pressure, suppressed deterioration in sound quality, good acoustic characteristics and no risk of cracking, and having a light weight, a thin shape, and low power consumption can be obtained.

It is a figure which shows the basic structure and comparative example of the piezoelectric acoustic element of this invention, (A-1) is a top view of this invention, (A-2) is sectional drawing at the time of the deformation | transformation of said (A-1), ( B-1) is a plan view of a comparative example, and (B-2) is a cross-sectional view at the time of deformation of (B-1). It is a figure which shows the piezoelectric speaker of Example 1 of this invention, (A) is an external appearance perspective view, (B) is an exploded perspective view. FIG. 3 is a plan view showing wiring of the piezoelectric acoustic element of Example 1. It is sectional drawing which cut | disconnected said FIG. 3 along the # B- # B line | wire and looked at the arrow direction. It is a connection example of the surface electrode shape of a bimorph type piezoelectric element and voltage application at the time of polarization, (A-1) and (A-2) show examples of a four-layer structure, and (B-1) and (B-2 ) Is a diagram showing an example of a six-layer structure. It is a graph which shows the frequency characteristic of the sound pressure level by the presence or absence of the cover film in the said Example 1. FIG.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

  First, the basic structure of the piezoelectric acoustic element of the present invention will be described with reference to FIG. 1A-1 is a plan view of the basic structure of the piezoelectric acoustic element of the present invention, and FIG. 1A-2 is a cross-sectional view taken along line # A- # A in FIG. It is sectional drawing at the time of the deformation | transformation seen in FIG. 1 (B-1) is a plan view of a piezoelectric acoustic element of a comparative example, and FIG. 1 (B-2) is a diagram (B-1) cut along line #A ′-# A ′ in the direction of the arrow. It is sectional drawing at the time of the deformation | transformation seen. As shown in FIG. 1 (A-1), the piezoelectric acoustic element 10 of the present invention has a matrix of a plurality of piezoelectric elements 20, 30, 40, 50 on one main surface 12A of a support 12 having flexibility. The structure is such that four piezoelectric elements in two vertical columns and two horizontal rows are arranged. For example, a polyimide resin is used as the support 12. The piezoelectric elements 20 to 50 are attached to the support main surface 12A with, for example, a double-sided tape 14 (see FIG. 4). In this embodiment, bimorph type piezoelectric elements are used as the piezoelectric elements 20 to 50. The piezoelectric elements 20 to 50 are substantially square to prevent deterioration in sound quality due to distortion during deformation.

  On the other hand, the piezoelectric acoustic element 200 of the comparative example shown in FIG. 1B-1 is provided with one bimorph type piezoelectric element 204 on one main surface 202A of a support 202 having flexibility. In the piezoelectric acoustic element 200 having such a structure, when the piezoelectric element 204 is enlarged in order to increase the sound pressure and the deformation is increased, the piezoelectric element 204 is cracked as shown in FIG. 206 may occur. On the other hand, in the piezoelectric acoustic element 10 of the present invention, as shown in FIG. 1 (A-1), the plurality of piezoelectric elements 20 to 50 are arranged in a matrix at appropriate intervals. For this reason, as shown in FIG. 1 (A-2), the deformation of the support 12 while suppressing the deformation of the piezoelectric elements 20 to 50 itself due to the deformation of the support between the plurality of piezoelectric elements 20 to 50. Can be increased. As a result, it is possible to obtain a lightweight, thin, and low power consumption piezoelectric acoustic element that has excellent acoustic characteristics, with no deterioration in sound quality even when the sound pressure is increased, and no risk of cracking.

  Next, a specific structure of a piezoelectric speaker using the piezoelectric acoustic element of the present invention will be described with reference to FIGS. 2A and 2B are diagrams showing the speaker of this embodiment, in which FIG. 2A is an external perspective view, and FIG. 2B is an exploded perspective view. FIG. 3 is a plan view showing the surface electrode shape and wiring of the piezoelectric acoustic element, and FIG. 4 is a cross-sectional view of FIG. 3 taken along line # B- # B and viewed in the direction of the arrow. FIG. 5 is an example of the surface electrode shape of a bimorph piezoelectric element and voltage application during polarization. (A-1) and (A-2) show an example of a four-layer structure, and (B-1) and (B B-2) is a diagram showing an example of a six-layer structure. FIG. 6 is a graph showing the frequency characteristics of the sound pressure level with and without the cover film.

  As shown in FIGS. 2A and 2B, the piezoelectric speaker 60 of the present embodiment has a structure in which the piezoelectric acoustic element 10 having the basic structure described above is housed in a housing 62. As shown in FIG. 2B, the casing 62 is composed of a case main body 64 and a lid 70, and is formed of, for example, PPS (polyphenylene sulfide) resin. The dimension of the housing 62 is, for example, 70 × 60 × 9 mm. The case main body 64 has a plurality of sound emitting holes 66 on the bottom surface 64A. A receiving portion 68 for supporting the piezoelectric acoustic element 10 is formed inside the case main body 64. After the mesh sheet 72 for protecting the sound emission hole 66 is bonded to the bottom surface 64A of the case 64 with a double-sided tape 74 or the like, the piezoelectric acoustic element 10 is bonded to the receiving portion 68 with the double-sided tape 76. At this time, bonding is performed so that the main surface 12B on the side where the piezoelectric elements 20 to 50 are not provided is on the sound emission hole 66 side. As the double-sided tape 76, for example, a waterproof foam double-sided tape is used.

  Next, a metal frame 80 for pressing the periphery of the piezoelectric acoustic element 10 against the case main body 64 without a gap is attached using a double-sided tape 78. Further, the piezoelectric acoustic element 10 is suppressed by the resin frame 82 from above, and the lid 70 is bonded using an adhesive (not shown). The shape of the periphery of the piezoelectric acoustic element 10 is maintained by holding the piezoelectric acoustic element 10 to the casing 62 by the metal frame 80 and the resin frame 82.

  FIG. 3 shows an example of the surface electrode shape and the wiring shape of the piezoelectric elements 20 to 50 of the piezoelectric acoustic element 10. In the present embodiment, as the piezoelectric elements 20 to 50, stacked bimorph piezoelectric elements in which piezoelectric layers and electrode layers are alternately stacked are used. The piezoelectric element 20 will be described as an example. As shown in FIG. 4, the piezoelectric element 20 has a structure in which a plurality of piezoelectric layers 22 and electrode layers 24 are alternately stacked. The pattern is divided into three patterns 26A to 26C. The three portions are formed for voltage application during polarization. When used as a piezoelectric speaker, two patterns (in the example shown, patterns 26B and 26C) are formed into a conductive paste 27. Connect with. The application of voltage at the time of polarization will be described later.

  The other piezoelectric elements 30, 40, and 50 have the same configuration. The piezoelectric element 30 has the piezoelectric layers 32 and the electrode layers 34 alternately stacked, and the uppermost surface electrode 34A has three patterns 36A to 36C. Among them, the patterns 36 </ b> B and 36 </ b> C are electrically connected by the conductive paste 27. In the piezoelectric element 40, the piezoelectric layers 42 and the electrode layers 44 are alternately stacked, and the uppermost surface electrode 44 </ b> A has the patterns 46 </ b> B and 46 </ b> C conducted by the conductive paste 27 among the three patterns 46 </ b> A to 46 </ b> C. In the piezoelectric element 50, the piezoelectric layers 52 and the electrode layers 54 are alternately stacked, and the uppermost surface electrode 54A is such that the patterns 56B and 56C among the three patterns 56A to 56C are electrically connected by the conductive paste 27. Yes. The piezoelectric elements 20 to 50 have dimensions of about 13.6 × 17.6 mm, for example.

  By arranging the piezoelectric elements 20 to 50 having such a surface electrode shape in a matrix on the main surface 12A of the support 12, a cross-shaped space is formed between the piezoelectric elements 20 to 50. In the present embodiment, a substantially cross-shaped wiring 90 for connecting the electrodes of the piezoelectric elements 20 to 50 is formed in the cross-shaped space, and the wiring 100 is surrounded so as to surround the piezoelectric elements 20 to 50. Is forming. The wirings 90 and 100 are formed by a pattern such as a copper foil, for example. Since the rigidity of the support 12 is low, the sound quality can be stabilized by increasing the rigidity and stabilizing the displacement by providing metal wiring between and between the piezoelectric elements 20 to 50.

  In the substantially cross-shaped wiring 90, lead portions 92 and 94 are formed at both ends of the wiring formed between the piezoelectric elements 20 and 30 and between the piezoelectric elements 40 and 50. One end 92 A of the lead-out portion 92 is connected to the pattern 26 B of the piezoelectric element 20 by the conductive paste 96, and the other end 92 B is connected to the pattern 36 A of the piezoelectric element 30 by the conductive paste 96. . One end 94A of the lead-out portion 94 is connected to the pattern 56B of the piezoelectric element 50 by the conductive paste 96, and the other end 94B is connected to the pattern 46A of the piezoelectric element 40 by the conductive paste 96. ing.

  Further, lead portions 102A to 102D are provided at appropriate positions of the wiring 100 provided around the piezoelectric elements 20 to 50, and the lead portion 102A is connected to the pattern 26A of the piezoelectric element 20 by the conductive paste 104. ing. The lead portion 102B is connected to the pattern 36B of the piezoelectric element 30 by the conductive paste 104, the lead portion 102C is connected to the pattern 46B of the piezoelectric element 40 by the conductive paste 104, and the lead portion 102D is piezoelectric by the conductive paste 104. It is connected to the pattern 56A of the element 50. The wirings 90 and 100 are connected to terminal terminals 108A and 108B by connection portions 98 and 106, respectively. These connecting portions are covered with an insulating tape 109. A cover film 120 is provided on the wirings 90 and 100 so as to surround the periphery of the piezoelectric elements 20 to 50. As the cover film 120, for example, a PET film is used, and is bonded to the support main surface 12A side of the piezoelectric acoustic element 10 with a double-sided tape (not shown). By providing the cover film 120, the deformation of the cover film 120 further promotes the deformation of the support 12 and the sound pressure is increased.

  In order to realize the connection of the electrodes by the wirings 90 and 100 having the shapes as described above, the polarization direction is set so that the vibration directions (deformation directions) of the piezoelectric elements 20 to 50 are the same in the stacking direction. FIG. 5 shows an example of electrode connection during polarization. First, the case of the four-layer structure shown in FIGS. 5A-1 and 5A-2 will be described. As shown in FIG. 5 (A-2), the piezoelectric element 150 has a structure in which four piezoelectric layers 152A to 152D and electrode layers 154 to 162 are alternately stacked.

  The uppermost electrode layer (surface electrode) 154 is formed in three patterns 154A to 154C. In the illustrated example, the pattern 154A is a plus side electrode, the pattern 154B is a minus side electrode, and the pattern 154C is a common electrode. . The internal electrode layers are appropriately connected to these patterns 154A to 154C through through holes or the like. For example, the pattern 154A and the electrode layer 156 are connected, the pattern 154B and the electrode layer 160 are connected, and the pattern 154C and the electrode layers 158 and 162 are connected. Then, as shown in FIG. 5 (A-2), the polarization process is performed by applying a voltage for polarization. By reversing the connection on the plus side and the minus side, the polarization direction can be reversed. After the polarization is completed, the two patterns are connected to form one electrode.

  Next, the case of a six-layer structure will be described. The piezoelectric element 180 has a structure in which six piezoelectric layers 182A to 182F and electrode layers 184 to 196 are alternately stacked as shown in FIG. It has become. In the uppermost layer, three patterns 184A to 184C are formed. In the illustrated example, the pattern 184A is a positive electrode, the pattern 184B is a negative electrode, and the pattern 184C is a common electrode. The internal electrode layers are appropriately connected to these patterns 184A to 184C through through holes or the like. For example, the pattern 184A and the electrode layer 188 are connected, the pattern 184B and the electrode layers 192 and 196 are connected, and the pattern 184C and the electrode layers 186, 190, and 194 are connected. Then, a polarization process is performed by applying a voltage as shown in FIG. In this case as well, as in the case of the four-layer structure, the polarization direction can be reversed by reversing the connection on the plus side and the minus side. That is, the laminated bimorph piezoelectric element of this example has three electrodes, and has a structure having two lead portions by connecting the two electrodes after polarization.

  In the piezoelectric element subjected to the polarization treatment in this way, for example, the polarization directions of the adjacent piezoelectric elements 20 and 30 are reversed, the polarization directions of the adjacent piezoelectric elements 40 and 50 are reversed, and the adjacent piezoelectric elements. 30 and 40 are arranged so that the polarization directions are the same, and the polarization directions of adjacent piezoelectric elements 10 and 50 are the same. When a voltage is applied via the lead wires 110 and 112 connected to the terminals, the piezoelectric acoustic element 10 is bent and displaced in the stacking direction in the plurality of piezoelectric elements 20 to 50 with the same phase. Note that the number of stacked layers and the shape of the surface electrode shown in FIG. 5 are examples, and can be changed as appropriate. In this way, since piezoelectric elements having the same structure can be used, the displacement amount and phase between the piezoelectric elements can be made the same, and the generated sound interferes to efficiently generate sound waves. Therefore, sound quality deterioration can be suppressed and a stable sound can be obtained.

  FIG. 6 shows a graph showing the frequency characteristics of the sound pressure level with and without the cover film 120. In the figure, the horizontal axis represents frequency [Hz] and the vertical axis represents sound pressure level (SPL) [dB]. It can be seen that even if there is no cover film 120 (“no resin layer”), the frequency band near 700 Hz to 2.5 kHz can be controlled to a high sound pressure. Furthermore, as shown in the figure, it can be seen that by providing the cover film 120 (“with resin layer”), the sound pressure is increased in the vicinity of 1 kHz as compared with the case without the cover film 120. This is considered to be because the periphery of the piezoelectric acoustic element 10 is satisfactorily fixed by the cover film 120, and the deformation of the piezoelectric elements 20 to 50 is effectively converted into sound pressure. From the above results, the piezoelectric speaker 60 of the present embodiment uses four piezoelectric elements 20 to 50 having a size of 13.6 × 17.6 mm, and the connection patterns (wirings 90 and 100) and the piezoelectric elements 20 to 50 are used. In addition to the arrangement, by optimizing with the use of the cover film 120 as necessary, the frequency band in the vicinity of 700 Hz to 2.5 kHz can be controlled to a high sound pressure, and the piezoelectric speaker 60 is light, thin, and has low consumption electrodes. Can be realized.

Thus, according to the first embodiment, there are the following effects.
(1) By disposing the plurality of piezoelectric elements 20 to 50 in a matrix on one main surface 12A of the support body 12 having flexibility, the support body portion between the plurality of piezoelectric elements 20 to 50 is deformed. The deformation amount of the support 12 is increased while the deformation amount of the piezoelectric elements 20 to 50 is suppressed. For this reason, even if the sound pressure is increased, the occurrence of cracks is prevented, the deterioration of sound quality is suppressed, and the piezoelectric acoustic element 10 and the piezoelectric speaker 60 that are lightweight, thin, and have low power consumption with good acoustic characteristics can be obtained.
(2) Since the piezoelectric elements 20 to 50 are substantially square, they are closer to a circle than a rectangle or the like, so that distortion during deformation can be suppressed and deterioration of sound quality can be prevented.

(3) Since the wires 90 and 100 for connecting the electrodes of the piezoelectric elements 20 to 50 are provided in a substantially cross shape between the piezoelectric elements 20 to 50 and around the piezoelectric elements 20 to 50, rigidity is improved. This improves the displacement and stabilizes the sound quality.
(4) Since the polarization directions are set so that the piezoelectric elements 20 to 50 are bent and displaced in the laminating direction at the same phase, the connection by the wirings 90 and 100 can be realized, and unnecessary wiring is eliminated. Can do. For this reason, it is possible to prevent deterioration in sound quality due to the difference in rigidity between the extra wiring portion and other portions.
(5) Since the wirings 90 and 100 are wired only on the one main surface 12A side of the support body 12, they are suitable as a waterproof structure and the wiring itself is easy.

(6) Since bimorph type piezoelectric elements are used as the piezoelectric elements 20 to 50, the element can be deformed as a single element.
(7) By providing the cover film 120 around the piezoelectric elements 20 to 50, the support 12 is further deformed and the sound pressure is improved.
(8) Since the piezoelectric acoustic element 10 is pressed against the casing 62 using the metal frame 80 and the resin frame 82, the shape of the periphery of the piezoelectric acoustic element 10 can be fixed and supported well.
(9) Since the double-sided tape or the like is used to attach the piezoelectric acoustic element 10 to the housing 62, the manufacturing process of the piezoelectric speaker 60 can be simplified.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The dimensions and shapes of the piezoelectric elements 20 to 50 shown in the above embodiments are merely examples, and may be appropriately changed as necessary, such as a circular shape. Moreover, although the four piezoelectric elements 20-50 were used in the said Example, you may increase / decrease the number of piezoelectric elements as needed.
(2) In the above embodiment, a bimorph type piezoelectric element having a laminated structure is used as the piezoelectric elements 20 to 50. However, this is also an example, and the piezoelectric element may be a unimorph type or not a laminated structure. It may be a single layer structure.
(3) The polarization direction and applied voltage shown in the above embodiment are also examples, and the polarization direction and applied voltage of the piezoelectric element may be set as appropriate so that the vibration direction of the piezoelectric element is the same. For example, in the electrode pattern shown in FIG. 3, the polarization direction may be set to be reversed between all adjacent piezoelectric elements. For example, the polarization direction and the wiring pattern are set so that a positive voltage is applied to the largest patterns 26A and 46A of the piezoelectric elements 20 and 40, and a negative voltage is applied to the largest patterns 36A and 56A of the piezoelectric elements 30 and 50. Etc.
(4) The materials shown in the above embodiments are also examples, and various known materials may be used as long as the same effects can be obtained.
(5) The position and number of the sound emission holes 66 of the housing 62 shown in the above embodiment are also examples, and can be changed or increased or decreased as necessary.
(6) The above-described embodiment is an example suitable for a vehicle-mounted small speaker or the like, but the present invention can be applied as a piezoelectric acoustic element used for various other known acoustic devices.

  According to the present invention, by arranging a plurality of piezoelectric elements in a matrix on one main surface of a flexible support, deformation of the piezoelectric elements is caused by deformation of the support portion between the plurality of piezoelectric elements. The amount of deformation of the support was increased while the amount was suppressed. For this reason, the sound pressure is high, deterioration of the sound quality is suppressed, there is no fear of cracking, good acoustic characteristics can be obtained, and the weight, thickness, and power consumption can be reduced. In particular, it is suitable for vehicle-related acoustic applications (for example, hybrid vehicle approach warning speakers, headless application speaker units, etc.).

10: Piezoelectric acoustic element 12: Support body 12A, 12B: Main surface 14: Double-sided tape 20, 30, 40, 50: Piezoelectric element 22, 32, 42, 52: Piezoelectric layer 24, 34, 44, 54: Electrode layer 24A , 34A, 44A, 54A: surface electrodes 26A-26C, 36A-36C, 46A-46C, 56A-56C: pattern 27: conductive paste 60: piezoelectric speaker 62: housing 64: case main body 64A: bottom surface 66: sound emission Hole 68: Receiving portion 70: Cover 72: Mesh sheet 74, 76, 78: Double-sided tape 80: Metal frame 82: Resin frame 90: Wiring 92, 94: Lead-out portion 92A, 92B, 94A, 94B: End portion 96, 104 : Conductive paste 98, 106: Connection part 100: Wiring 102A-102D: Lead-out part 108A, 108B: Terminal terminal 109: Insulating tape 110, 112: lead wire 120: cover film 150: piezoelectric elements 152A to 152D: piezoelectric layers 154 to 162: electrode layers 154A to 154C: pattern 180: piezoelectric elements 182A to 182F: piezoelectric layers 184 to 196: electrode layers 184A to 184C : Electrode pattern 200: Piezoelectric acoustic element 202: Support body 202A: Main surface 204: Piezoelectric element 206: Crack

Claims (7)

  A piezoelectric acoustic element comprising a plurality of piezoelectric elements arranged in a matrix on one main surface of a flexible support.   The piezoelectric acoustic element according to claim 1, wherein a resin layer is formed around the plurality of piezoelectric elements. A metal wire connecting the plurality of piezoelectric elements,
3. The piezoelectric acoustic element according to claim 1, wherein wiring is performed between the plurality of piezoelectric elements and around the plurality of piezoelectric elements. There are four piezoelectric elements,
4. The piezoelectric acoustic element according to claim 3, wherein the metal wire wired between the piezoelectric elements has a substantially cross shape. The piezoelectric element is a bimorph type,
5. The piezoelectric acoustic element according to claim 4, wherein the piezoelectric element has a polarization direction different from that of another piezoelectric element adjacent on the support. The piezoelectric acoustic element according to any one of claims 1 to 5,
A housing that supports the outer periphery of the piezoelectric acoustic element and has a sound emitting hole on the main surface side of the support on the side where the piezoelectric element is not disposed;
A frame that is disposed between the main surface of the support on the side where the piezoelectric element is disposed and the lid of the casing, and holds the outer periphery of the piezoelectric acoustic element against the casing;
A piezoelectric speaker characterized by comprising: The frame is
A metal frame disposed on the piezoelectric acoustic element side;
A resin frame disposed between the metal frame and the lid of the housing;
The piezoelectric speaker according to claim 6, comprising:

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