Transducer and electronic appliance

Abstract

To provide a transducer that suppresses air leak and has resistance against impact.SOLUTION: A transducer includes: a piezoelectric element including a pair of electrodes and a piezoelectric film held between the pair of electrodes; a film body including a film support part having a hollow part, and a vibration film that is connected to the film support part and is displaceable in a film thickness direction, in which the piezoelectric element is stacked on the vibration film; and a contact member that restricts the displacement of the vibration film. An end part of the piezoelectric element includes a region overlapping the film support part.SELECTED DRAWING: Figure 21

Description

[Technical Field]

[0001] The present embodiment relates to a transducer and an electronic device. [Background technology]

[0002] 2. Description of the Related Art Transducers that transmit or receive sound waves or ultrasonic waves are known. Transducers are used, for example, as speakers that transmit sound waves, and are mounted in earphones, wearable devices, and the like.

[0003] For example, Patent Document 1 discloses a sound generating device suitable for earphones. This sound generating device includes a coil that generates a magnetic field and a magnet that interacts with the magnetic field generated by the coil to vibrate a diaphragm.

[0004] Speakers that use a coil and a magnet require a current to flow through the coil to generate a magnetic field, resulting in high power consumption. Therefore, speakers that use a piezoelectric element consisting of a piezoelectric film sandwiched between a pair of electrodes have been attracting attention (see, for example, Patent Document 2). Speakers of this type are manufactured using MEMS (Micro Electro Mechanical Systems), a semiconductor manufacturing technology that enables microfabrication. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-170592 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-105170 Summary of the Invention [Problem to be solved by the invention]

[0006] When a drive voltage is repeatedly applied to a pair of electrodes, the piezoelectric element and the diaphragm alternately displace upward and downward. Specifically, the tip of the diaphragm displaces in a warping manner. The vibration of the diaphragm vibrates the air around the diaphragm, and the air vibrations are output as sound waves. However, when a drive voltage is applied to the pair of electrodes, the piezoelectric element contracts, and the piezoelectric film of the piezoelectric element may warp (the diaphragm may also warp) in a direction parallel to the base (connection) of the diaphragm. This warping distorts the air vibrations. Furthermore, when the air around the diaphragm vibrates, if the internal space for the diaphragm to displace is too large, air leakage occurs, distorting the air vibrations. These distortions can affect the air vibrations. This effect can lead to defects, such as partial cancellation of the vibrations, making it impossible to transmit sound waves efficiently.

[0007] Furthermore, speaker units manufactured using MEMS are becoming smaller and have finer shapes, making them prone to fragile structures and therefore susceptible to damage from external impacts.

[0008] One aspect of this embodiment provides a transducer that suppresses warping of the piezoelectric membrane in a direction parallel to the connection between the membrane support and the vibration membrane, a transducer that suppresses air leakage and has resistance to impacts, etc., and an electronic device that includes a speaker unit with a smaller housing. [Means for solving the problem]

[0009] One aspect of this embodiment is a transducer comprising: a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in a thickness direction; a pair of electrodes; and a piezoelectric element on the vibration membrane, the piezoelectric element comprising a piezoelectric membrane sandwiched between the pair of electrodes; in a region overlapping the hollow portion, a plurality of first regions having a first total thickness that is the sum of the thickness of the vibration membrane and the thickness of the piezoelectric element; and a plurality of second regions having a second total thickness that is different from the first total thickness and is the sum of the thickness of the vibration membrane and the thickness of the piezoelectric element, the first regions and the second regions being arranged alternately, and one of the first regions being adjacent to the connection portion between the membrane support portion and the vibration membrane.

[0010] Another aspect of this embodiment is a transducer having a membrane support part having a hollow part, a vibration membrane connected to the membrane support part and displaceable in the film thickness direction, a piezoelectric element on the vibration membrane, the piezoelectric element comprising a pair of electrodes, a piezoelectric membrane sandwiched between the pair of electrodes, and multiple buffer layers on the pair of electrodes, wherein in a region overlapping with the hollow part, the transducer has a first region that does not include the buffer layer and a second region that includes the buffer layer, the first region and the second region are arranged alternately, and one of the first regions is adjacent to the connection part between the membrane support part and the vibration membrane.

[0011] Another aspect of this embodiment is a transducer comprising: a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in the membrane thickness direction; a pair of electrodes; and a piezoelectric element on the vibration membrane, the piezoelectric element comprising a piezoelectric membrane sandwiched between the pair of electrodes; wherein the vibration membrane has a plurality of recesses, and in a region overlapping with the hollow portion, the vibration membrane has a first region that does not include the recesses and a second region that includes the recesses, the first region and the second region are arranged alternately, and one of the first regions is adjacent to the connection portion between the membrane support portion and the vibration membrane.

[0012] Another aspect of this embodiment is a transducer comprising: a piezoelectric element having a pair of electrodes and a piezoelectric membrane sandwiched between the pair of electrodes; a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in the thickness direction of the membrane; a membrane body on which the piezoelectric element is stacked; and an abutment member that limits the displacement of the vibration membrane, wherein an end of the piezoelectric element has an area that overlaps with the membrane support portion.

[0013] Another aspect of this embodiment is an electronic device having a speaker unit including a substrate, and a bottomed cylindrical housing that houses the speaker unit, the housing having a cylindrical portion and a bottom that contacts the cylindrical portion, the substrate being disposed on a part of the cylindrical portion and a part of the bottom, the bottom being separated from the cylindrical portion via the speaker unit, and the speaker unit having an air vent in the film thickness direction that connects the space at the bottom to the outside of the housing via the air vent.

[0014] Another aspect of this embodiment is an electronic device having a speaker unit including a substrate, and a bottomed cylindrical housing that houses the speaker unit, the housing having a cylindrical portion and a bottom that contacts the cylindrical portion, the substrate being arranged on a part of the cylindrical portion and a part of the bottom, the bottom being separated from the cylindrical portion via the speaker unit, and the speaker unit having an air vent on a side that connects the space at the bottom to the outside of the housing via the air vent. [Effects of the Invention]

[0015] According to this embodiment, it is possible to provide a transducer that suppresses warping of the piezoelectric membrane in a direction parallel to the connection between the membrane support and the vibration membrane. It is also possible to provide a transducer that suppresses air leakage and has resistance to impacts. It is also possible to provide an electronic device that includes a speaker unit with a smaller housing. [Brief explanation of the drawings]

[0016] [Figure 1]FIG. 1 is a cross-sectional view of one form of a transducer according to the first embodiment. [Figure 2] FIG. 2 is a top view of one form of the transducer according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of another form of the transducer according to the first embodiment. [Figure 4] FIG. 4 is a top view of another form of the transducer according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view of one form of the transducer according to the second embodiment. [Figure 6] FIG. 6 is a top view of one form of the transducer according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view of one form of the transducer according to the third embodiment. [Figure 8] FIG. 8 is a top view of one form of the transducer according to the third embodiment. [Figure 9] FIG. 9 is a cross-sectional view of one form of a transducer according to the fourth embodiment. [Figure 10] FIG. 10 is a top view of one form of the transducer according to the fourth embodiment. [Figure 11] FIG. 11 is a cross-sectional view of another form of the transducer according to the fourth embodiment. [Figure 12] FIG. 12 is a top view of another form of the transducer according to the fourth embodiment. [Figure 13] FIG. 13 is a cross-sectional view of another form of the transducer according to the fourth embodiment. [Figure 14] FIG. 14 is a top view of another form of the transducer according to the fourth embodiment. [Figure 15] FIG. 15 is a cross-sectional view of another form of the transducer according to the fourth embodiment. [Figure 16] FIG. 16 is a top view of another form of the transducer according to the fourth embodiment. [Figure 17]FIG. 17 is a cross-sectional view of another form of the transducer according to the fourth embodiment. [Figure 18] FIG. 18 is a top view of another form of the transducer according to the fourth embodiment. [Figure 19] FIG. 19 is a cross-sectional view of another form of the transducer according to the fourth embodiment. [Figure 20] FIG. 20 is a top view of another form of the transducer according to the fourth embodiment. [Figure 21] FIG. 21 is a cross-sectional view of a transducer according to a fifth embodiment. [Figure 22] FIG. 22 is a top view of a transducer according to the fifth embodiment. [Figure 23] FIG. 23 is a cross-sectional view of a transducer according to a first modified example. [Figure 24] FIG. 24 is a top view of a transducer according to a first modified example. [Figure 25] FIG. 25 is a cross-sectional view of a transducer according to a second modified example. [Figure 26] FIG. 26 is a cross-sectional view of a transducer according to a third modified example. [Figure 27A] FIG. 27A is a cross-sectional view of a slit 132 in a region 130 of a transducer according to a third modified example, as viewed from the air inlet / outlet side. [Figure 27B] FIG. 27B is a cross-sectional view of the slit 133 in the region 131 of the transducer according to the third modification, as viewed from the air inlet / outlet side. [Figure 28] FIG. 28 is a cross-sectional view of a transducer according to a fourth modified example. [Figure 29] FIG. 29 is a cross-sectional view of a transducer according to a fifth modified example. [Figure 30] FIG. 30 is a top view of a transducer according to a fifth modified example. [Figure 31A] FIG. 31A is an overall view of an earphone as an example of an electronic device according to a sixth embodiment. [Figure 31B]FIG. 31B is a diagram illustrating a housing of an earphone as an example of an electronic device according to the sixth embodiment. [Figure 32] FIG. 32 is a diagram illustrating the configuration of the speaker unit in the first implementation example. [Figure 33] FIG. 33 is a cross-sectional view of the earphone in the first implementation example. [Figure 34] FIG. 34 is a diagram illustrating the configuration of a speaker unit in the second implementation example. [Figure 35] FIG. 35 is a cross-sectional view of the earphone in the second implementation example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, this embodiment will be described with reference to the drawings. In the drawings described below, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and planar dimensions of each component may differ from the actual relationship. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0018] Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical ideas, and do not specify the materials, shapes, structures, arrangements, etc. of each component part. Various modifications can be made to the present embodiments within the scope of the claims.

[0019] A specific aspect of this embodiment is as follows.

[0020] <1> a piezoelectric element on the vibration membrane, the piezoelectric element comprising: a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in a thickness direction; a pair of electrodes; and a piezoelectric membrane sandwiched between the pair of electrodes; wherein in an area overlapping with the hollow portion, the transducer has a plurality of first regions having a first total thickness which is the sum of the thickness of the vibration membrane and the thickness of the piezoelectric element; and a plurality of second regions having a second total thickness which is the sum of the thickness of the vibration membrane and the thickness of the piezoelectric element and which is different from the first total thickness; the first regions and the second regions are arranged alternately, and one of the first regions is adjacent to the connection portion between the membrane support portion and the vibration membrane.

[0021] <2> A transducer comprising: a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and displaceable in a thickness direction; a piezoelectric element on the vibration membrane, the piezoelectric element comprising a pair of electrodes, a piezoelectric membrane sandwiched between the pair of electrodes, and a plurality of buffer layers on the pair of electrodes; wherein in a region overlapping with the hollow portion, the transducer has a first region that does not include the buffer layer and a second region that includes the buffer layer, the first region and the second region being arranged alternately, and one of the first regions is adjacent to the connection portion between the membrane support portion and the vibration membrane.

[0022] <3> The buffer layer is divided in one of the second regions. <2> The transducer according to claim 1.

[0023] <4> a width of one of the buffer layers in the second region is greater than a width of another of the buffer layers in the second region that is farther from the connecting portion than one of the buffer layers in the second region; <2> or <3> The transducer according to claim 1.

[0024] <5> the width of the one buffer layer in the second region increases toward the center in the longitudinal direction; <2> ~ <4> 10. A transducer according to any one of claims 1 to 9.

[0025] <6> the buffer layer includes multiple layers of different materials; <2> ~ <5> 10. A transducer according to any one of claims 1 to 9.

[0026] <7> the number of layers constituting one buffer layer in the second region is different from the number of layers constituting another buffer layer in the second region; <2> ~ <5> 10. A transducer according to any one of claims 1 to 9.

[0027] <8> A transducer comprising: a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in a thickness direction; a pair of electrodes; and a piezoelectric element on the vibration membrane, the piezoelectric element comprising a piezoelectric membrane sandwiched between the pair of electrodes; wherein the vibration membrane has a plurality of recesses, and in a region overlapping with the hollow portion, the vibration membrane has a first region that does not include the recesses and a second region that includes the recesses, the first region and the second region are arranged alternately, and one of the first regions is adjacent to the connection portion between the membrane support portion and the vibration membrane.

[0028] <9> The recess is disposed on the rear surface of the vibration membrane. <8> The transducer according to claim 1.

[0029] <10> a width of one recess in the second region is greater than a width of another recess in the second region that is farther from the connecting portion than one of the recesses in the second region; <8> or <9> The transducer according to claim 1.

[0030] <11> The width of one recess in the second region increases toward the center in the longitudinal direction. <8> ~ <10> 10. A transducer according to any one of claims 1 to 9.

[0031] <12> a depth of one recess in the second region and a depth of another recess in the second region are different from each other; <8> ~ <11> 10. A transducer according to any one of claims 1 to 9.

[0032] <13> One of the second regions is parallel to the connecting portion. <1> ~ <12> 10. A transducer according to any one of claims 1 to 9.

[0033] <14> One width of the second region is different from another width of the second region. <1> ~ <13> 10. A transducer according to any one of claims 1 to 9.

[0034] <15> The piezoelectric element has a piezoelectric slit. <1> ~ <14> 10. A transducer according to any one of claims 1 to 9.

[0035] <16> A transducer comprising: a piezoelectric element having a pair of electrodes and a piezoelectric membrane sandwiched between the pair of electrodes; a membrane support portion having a hollow portion; a vibration membrane connected to the membrane support portion and capable of displacement in a thickness direction of the membrane; a membrane body on which the piezoelectric element is stacked; and an abutment member that limits the displacement of the vibration membrane, wherein an end of the piezoelectric element has an area that overlaps with the membrane support portion.

[0036] <17> the piezoelectric element and the vibration membrane are disposed between the hollow portion and the contact member. <16> The transducer according to claim 1.

[0037] <18> The abutment member has a first opening, and an end of the first opening is rounded. <16> or <17> The transducer according to claim 1.

[0038] <19> The abutting member has a first opening and further has a first filter covering the first opening. <16> ~ <18> 10. A transducer according to any one of claims 1 to 9.

[0039] <20> the abutment member has a plurality of first through holes; <16> or <17> The transducer according to claim 1.

[0040] <21> The first through-holes become smaller as they move away from the vibration membrane. <20> The transducer according to claim 1.

[0041] <22> a second side surface of the contact member facing the first side surface of the contact member on the end side is formed in a tapered shape; <16> ~ <21> 10. A transducer according to any one of claims 1 to 9.

[0042] <23> The first side surface of the abutting member has a first slit on the end side. <16> ~ <22> 10. A transducer according to any one of claims 1 to 9.

[0043] <24> The first slit has a comb-like structure. <23> The transducer according to claim 1.

[0044] <25> The film further includes a substrate in contact with the film body, and the film body is sandwiched between the substrate and the contact member. <16> ~ <24> 10. A transducer according to any one of claims 1 to 9.

[0045] <26> the substrate has a second opening, and the edge of the second opening is rounded; <25> The transducer according to claim 1.

[0046] <27> the substrate has a second opening, and further has a second filter covering the second opening; <25> or <26> The transducer according to claim 1.

[0047] <28> the substrate has a plurality of second through holes; <25> ~ <27> 10. A transducer according to any one of claims 1 to 9.

[0048] <29> The second through-holes become smaller as they move away from the vibration membrane. <28> The transducer according to claim 1.

[0049] <30> The first side surface of the membrane support portion is tapered. <25> ~ <29> 10. A transducer according to any one of claims 1 to 9.

[0050] <31> The first side surface of the membrane support portion has a second slit on a side diagonally opposite to the end portion. <25> ~ <30> 10. A transducer according to any one of claims 1 to 9.

[0051] <32> The second slit has a comb-like structure. <31> The transducer according to claim 1.

[0052] <33> Further, the electrode has a wiring electrically connected to one of the pair of electrodes. <16> ~ <32> 10. A transducer according to any one of claims 1 to 9.

[0053] <34> The wiring is electrically connected to one of the pair of electrodes through a via provided in the membrane support portion. <33> The transducer according to claim 1.

[0054] <35> An electronic device comprising: a speaker unit including a substrate; and a bottomed cylindrical housing that houses the speaker unit inside, the housing having a cylindrical portion and a bottom that contacts the cylindrical portion, the substrate being arranged on a part of the cylindrical portion and a part of the bottom, the bottom being separated from the cylindrical portion via the speaker unit, the speaker unit having an air vent in a thickness direction that connects the space at the bottom to the outside of the housing via the air vent.

[0055] <36> An electronic device comprising: a speaker unit including a substrate; and a bottomed cylindrical housing that houses the speaker unit inside, the housing having a cylindrical portion and a bottom that contacts the cylindrical portion, the substrate being arranged on a part of the cylindrical portion and a part of the bottom, the bottom being separated from the cylindrical portion via the speaker unit, and the speaker unit having an air vent on a side surface that connects the space at the bottom to the outside of the housing via the air vent.

[0056] <37> The speaker unit includes a transducer, the transducer including a piezoelectric element having a pair of electrodes and a piezoelectric membrane sandwiched between the pair of electrodes, a membrane support portion having a hollow portion, and a vibration membrane connected to the membrane support portion and displaceable in a thickness direction, the piezoelectric element being stacked on the vibration membrane, and a contact member for limiting the displacement of the vibration membrane, and an end of the piezoelectric element has an area overlapping the membrane support portion. <35> or <36> The electronic device described in

[0057] The transducers according to the first to fourth embodiments described below are mainly composed of a piezoelectric element and a membrane. In some regions, the total thickness of the piezoelectric element and the membrane's vibration membrane is adjusted to form regions with different total thicknesses (for example, a first region with a first total thickness and a second region with a second total thickness), and the regions with different total thicknesses (for example, the first region and the second region) are arranged alternately.

[0058] Transducers according to first to fourth embodiments will be described with reference to the drawings.

[0059] (First embodiment) The configuration of the transducer 1 according to this embodiment will be described using Figures 1 and 2. The transducer 1 according to this embodiment is mainly composed of a piezoelectric element 10 and a film body 15. In the following description, the up and down directions are defined based on the state of the transducer 1 shown in Figure 2, but this does not limit the direction in which the transducer 1 is used.

[0060] The piezoelectric element 10 is composed of a pair of electrodes 11, 12, a piezoelectric film 13 sandwiched between the pair of electrodes 11, 12, and a plurality of buffer layers 18 on the pair of electrodes 11, 12. The pair of electrodes 11, 12 and the piezoelectric film 13 have a shape corresponding to the shape of a vibration film 16, which will be described later, and is rectangular in the example shown in Figures 1 and 2.

[0061] Although the present specification and the like describes the buffer layer as a part of the piezoelectric element, the present invention is not limited to this and may be interpreted as not including the buffer layer as a part of the piezoelectric element.

[0062] The buffer layer 18 is formed in a striped pattern on the electrode 11. The buffer layer 18 is formed parallel to a connecting portion 21 between the membrane support portion 17 and the vibration membrane 16, which will be described later. In this specification, "parallel" refers to a state in which two straight lines are arranged at an angle of between -5° and 5°, and also includes a state in which two lines form two concentric circles. Furthermore, if the ends of the connecting portion 21 and / or the buffer layer 18 are not straight but, for example, have a wavy or zigzag shape, they may be slightly deviated from the parallel orientation as long as the effect of the buffer layer 18, which will be described later, is not impaired.

[0063] 2 is located inside the edge of the electrode 11, but is not limited to this and may be flush with the edge of the electrode 11.

[0064] The buffer layer 18 may be formed, for example, in the same process as the wiring layer (not shown) and / or insulating layer (not shown) formed when manufacturing the transducer, or may be formed separately using a hard material such as titanium. By using a hard material, the bending strength of the buffer layer 18 is increased, and warping of the piezoelectric film 13 (and the vibrating film 16) in the direction parallel to the connecting portion 21 is suppressed. Furthermore, the width, film thickness, and pitch width between adjacent buffer layers 18, etc., of the buffer layer 18 are not particularly limited.

[0065] Each of the pair of electrodes 11, 12 is formed using a thin film of a conductive metal such as platinum, molybdenum, iridium, or titanium. One electrode 11 is located above the piezoelectric film 13 and connected to an electrode pad 11a, which is a circuit pattern for applying a drive voltage to the electrode 11. The other electrode 12 is located below the piezoelectric film 13 and connected to an electrode pad 12a, which is a circuit pattern for applying a drive voltage to the electrode 12.

[0066] The piezoelectric film 13 is made of, for example, a lead zirconate titanate (PZT) film. Other than lead zirconate titanate, the piezoelectric film 13 can also be made of aluminum nitride (AlN), zinc oxide (ZnO), lead titanate (PbTiO), or the like.

[0067] The membrane 15 is made up of a vibrating membrane 16 and a membrane support portion 17. The membrane 15 is made of, for example, silicon (Si). By etching the back surface of the membrane 15, the vibrating membrane 16 and the membrane support portion 17 are integrally formed.

[0068] The diaphragm 16 is made of a thin film and is configured to be displaceable in the film thickness direction, i.e., in the normal direction to the diaphragm 16 (the Z direction: up and down in the plane of the paper in FIG. 1, and the Z direction: perpendicular to the front and back of the paper in FIG. 2). When observed from a plane parallel to the diaphragm 16, the diaphragm 16 has a substantially rectangular shape.

[0069] The membrane support part 17 has a rectangular cylindrical inner peripheral surface that forms a cavity (hollow part) 20. The vibrating membrane 16 is inscribed on one side of the inner peripheral surface of the membrane support part 17, and thus the vibrating membrane 16 is supported by the membrane support part 17. The vibrating membrane 16 is connected to the upper end side of the membrane support part 17.

[0070] The transducer 1 also has a slit 2. The slit 2 is a cut that penetrates a vibrating body in which a piezoelectric element 10 and a vibrating membrane 16 are laminated in the thickness direction.

[0071] The diaphragm 16 has a cantilever shape that extends from the diaphragm support portion 17. The tip of the diaphragm 16 is configured as a free end. However, the diaphragm 16 is not limited to this, and may have a cantilever shape in which both ends are fixed by the diaphragm support portion 17.

[0072] In the region overlapping with the hollow portion 20, if the region not including the buffer layer 18 is defined as a first region 22 and the region including the buffer layer 18 is defined as a second region 23, the first region 22 and the second region 23 are alternately arranged. One of the first regions 22 is adjacent to the connecting portion 21. Furthermore, a first total film thickness, which is the sum of the film thickness of the vibrating membrane 16 in the first region 22 and the film thickness of the piezoelectric element 10 excluding the buffer layer 18, differs from a second total film thickness, which is the sum of the film thickness of the vibrating membrane 16 in the second region 23 and the film thickness of the piezoelectric element 10 including the buffer layer 18, i.e., differs by the film thickness of the buffer layer 18.

[0073] In the transducer 1 configured as described above, a piezoelectric element 10 is provided on the vibrating membrane 16 of the membrane body 15. That is, a lower electrode 12, a piezoelectric membrane 13, and an upper electrode 11 are layered in this order on the vibrating membrane 16. When a driving voltage is applied to each of the pair of electrodes 11 and 12, a potential difference is generated between the pair of electrodes 11 and 12. This potential difference causes the vibrating membrane 16 to displace. Specifically, the tip side of the vibrating membrane 16 is displaced so as to bend.

[0074] By repeatedly applying a drive voltage to the pair of electrodes 11 and 12, the vibrating membrane 16 alternately displaces upward and downward. The vibration of the vibrating membrane 16 vibrates the air around the vibrating membrane 16, and the vibration of the air is output as a sound wave.

[0075] By providing the buffer layer 18 as described above, the buffer layer 18 can alleviate the stress of the piezoelectric film 13 in the direction parallel to the connecting portion 21, thereby suppressing warping of the piezoelectric film 13 in that direction. This suppresses distortion in the vibrating film 16, allowing the vibrating film 16 to vibrate appropriately.

[0076] In addition, in this embodiment, as shown in FIG. 1, the buffer layer 18 is formed from near the center of the vibration membrane 16 to the tip, but this is not limited to this. For example, as shown in FIGS. 3 and 4, the transducer 1A may have the buffer layer 18 formed from near the connecting portion 21 to the tip.

[0077] (Second embodiment) The configuration of a transducer 1B according to this embodiment will be described with reference to Figures 5 and 6. The transducer 1B according to this embodiment differs from the transducer 1 according to the first embodiment in that a vibration membrane having a recess is used instead of a buffer layer. In this embodiment, the description of the first embodiment will be used for the points common to both the first and second embodiments, and the points of difference will be described below.

[0078] The membrane body 15 is composed of a vibrating membrane 16a and a membrane support portion 17. The vibrating membrane 16a has a plurality of recesses 19 on the back surface side. The vibrating membrane 16a can be formed by etching the back surface side of the vibrating membrane 16 of the first embodiment.

[0079] The vibrating membrane 16a has a stripe shape in which a plurality of recesses 19 are arranged, and the recesses 19 are formed parallel to the connecting portion 21. Furthermore, the width and depth of the recesses 19, the pitch between adjacent recesses 19, and the like are not particularly limited.

[0080] In the region overlapping with hollow portion 20, if the region not including recess 19 is defined as first region 24 and the region including recess 19 is defined as second region 25, first region 24 and second region 25 are alternately arranged. One of first regions 24 is adjacent to connecting portion 21. Furthermore, a first total film thickness, which is the sum of the film thickness of vibration membrane 16a in the region that is not a recess in first region 24 and the film thickness of piezoelectric element 10, differs from a second total film thickness, which is the sum of the film thickness of vibration membrane 16a in the region that is recess 19 in second region 25 and the film thickness of piezoelectric element 10; in other words, the difference is the depth of recess 19.

[0081] By providing the recesses 19 as described above, the recesses 19 can relieve the stress on the piezoelectric film 13 in the direction parallel to the connecting portions 21, thereby suppressing warping of the piezoelectric film 13 in that direction. This suppresses distortion in the vibrating film 16a, allowing the vibrating film 16a to vibrate appropriately.

[0082] In addition, in this embodiment, as shown in Figure 5, the recess 19 is arranged from near the center of the vibration membrane 16a to the tip, but this is not limited to this, and for example, the recess 19 may be arranged from near the connecting portion 21 to the tip.

[0083] (Third embodiment) The configuration of a transducer 1C according to this embodiment will be described with reference to Figures 7 and 8. The transducer 1C according to this embodiment differs from the transducer 1 according to the first embodiment in that the piezoelectric element 10 has a piezoelectric slit 14. In this embodiment, the description of the first embodiment will be used for the points common to both the first and second embodiments, and the points of difference will be described below.

[0084] Piezoelectric element 10 has piezoelectric slit 14 penetrating piezoelectric element 10 in the thickness direction. Piezoelectric slit 14 extends to slit 2 in a direction perpendicular to connecting portion 21. In this specification, "perpendicular" refers to a state in which two straight lines are arranged at an angle of 85° to 95°. Furthermore, the orientation may deviate slightly from the perpendicular as long as it does not impair the effect of piezoelectric slit 14, which will be described later.

[0085] Since the piezoelectric slits 14 divide the vibration membrane 16 in a direction parallel to the connecting portion 21, it is possible to suppress warping of the piezoelectric membrane 13 in that direction. As a result, it is possible to suppress the occurrence of distortion in the vibration membrane 16 and to allow the vibration membrane 16 to vibrate appropriately.

[0086] By providing the piezoelectric slits 14 in addition to the buffer layer 18, warping of the piezoelectric film 13 in the vibrating film 16 can be further suppressed.

[0087] Furthermore, although the buffer layer 18 shown in FIG. 7 is provided so as to straddle the piezoelectric slits 14, the present invention is not limited to this, and the buffer layer 18 may be divided by the piezoelectric slits 14.

[0088] (Fourth embodiment) The shape, pitch width, etc. of the buffer layer (or recesses) of the transducer according to the above-described embodiment may be changed as appropriate, for example, as follows.

[0089] For example, a divided buffer layer 18a may be disposed on the electrode 11 as in a transducer 1D shown in Figures 9 and 10, or the width of the buffer layer 18b closer to the connecting portion 21 may be greater than the width of the buffer layer 18 further from the connecting portion 21 than the buffer layer 18b as in a transducer 1E shown in Figures 11 and 12. Furthermore, a buffer layer 18c may be disposed on the electrode 11 as in a transducer 1F shown in Figures 13 and 14. The width of the buffer layer 18c increases toward the center in the longitudinal direction.

[0090] The buffer layer may be composed of two or more layers of the same or different materials, and for example, a buffer layer 18d may be provided on the buffer layer 18 as in the transducer 1G shown in Figures 15 and 16, or the buffer layer 18 and the buffer layer 18d may have a tapered shape as in the transducer 1H shown in Figures 17 and 18. Also, a buffer layer 18d may be provided on a portion of the multiple buffer layers 18 as in the transducer 1I shown in Figures 19 and 20, and for example, the number of layers constituting the buffer layer closer to the connecting portion 21 may be different from the number of layers constituting the buffer layer farther from the connecting portion 21.

[0091] Furthermore, if a hard material is used for the buffer layer, the hard material may inhibit the contraction of the piezoelectric film 13 in the direction perpendicular to the connecting portion 21, which may reduce the efficiency of air vibration. For this reason, it is preferable to provide a soft material below the hard material. Examples of soft materials include an insulating layer such as silicon oxide, a resin, etc., and a configuration may be used in which silicon oxide, which is a soft material, is provided for buffer layer 18a and titanium, which is a hard material, is provided for buffer layer 18d as shown in Figures 9 and 10.

[0092] Although not shown, the same applies to the recesses 19 of the second embodiment, for example, the width of the recesses closer to the connecting portion 21 may be greater than the width of the recesses further away from the connecting portion 21. Furthermore, recesses whose width increases toward the center in the longitudinal direction may be provided. Also, recesses of different depths may be provided.

[0093] (Fifth embodiment) The configuration of the transducer 101 according to this embodiment will be described using Figures 21 and 22. The transducer 101 according to this embodiment is mainly composed of a piezoelectric element 110, a film 115, a contact member 118, and a substrate 119. In the following description, the up and down directions are defined based on the state of the transducer 101 shown in Figure 21, but this does not limit the direction in which the transducer 101 is used.

[0094] Piezoelectric element 110 is composed of a pair of electrodes 111, 112 and a piezoelectric film 113 sandwiched between the pair of electrodes 111, 112. The pair of electrodes 111, 112 and piezoelectric film 113 have shapes corresponding to the shape of vibration film 116, which will be described later, and are rectangular in the example shown in FIGS.

[0095] The contact member 118 is disposed so as to face the vibrating membrane 116. The contact member 118 has a function of controlling the displacement of the vibrating membrane 116. That is, when the vibrating membrane 116 is displaced toward the space 200, the contact member 118 controls the displacement of the vibrating membrane 116 by causing the vibrating membrane 116 or the piezoelectric element 110 on the vibrating membrane 116 to come into contact with the contact member 118.

[0096] The distance between the contact surface of contact member 118, with which vibrating membrane 116 comes into contact, and vibrating membrane 116 is set based on the displacement of vibrating membrane 116 when a rated voltage is applied to piezoelectric element 110 (hereinafter referred to as "maximum displacement"). In other words, the contact surface of contact member 118 is set so that vibrating membrane 116 or piezoelectric element 110 (a laminate of these is also referred to as a vibrating body) comes into contact with the contact surface when a displacement greater than the maximum displacement occurs. This allows vibrating membrane 116 or piezoelectric element 110 to come into contact with the contact surface when a large displacement exceeding the maximum displacement occurs in the vibrating body due to an impact or the like, without interfering with the normal displacement of vibrating membrane 116 caused by piezoelectric element 110.

[0097] The shape of the contact surface is formed based on the displacement shape of vibrating membrane 116. As a result, when vibrating membrane 116 contacts the contact surface, the contact surface makes surface contact with vibrating membrane 116. For example, the contact surface of the contact member disposed in space 200 may have a hemispherical shape that curves upward.

[0098] An opening 118a is formed in the center of the contact member 118. Furthermore, in the space 200 between the vibrating membrane 116 and the contact member 118, air vibrates due to the displacement of the vibrating membrane 116, and the air flows to the outside of the transducer 101 through the opening 118a. When air flows through the space 200, the distance (gap) between the contact surface of the vibrating membrane 116 and the contact member 118 is sufficient to allow the vibrating membrane 116 to be displaced up and down, and the smaller the distance, the better. For example, the gap is 5 to 30 μm. By reducing the gap, air leakage can be suppressed and the air can be vibrated efficiently. Furthermore, as shown in FIG. 22, the opening 118a preferably has rounded edges. By rounding the edges of the opening 118a, stress concentration at the edges can be alleviated.

[0099] Each of the pair of electrodes 111, 112 is formed using a thin film of a conductive metal such as platinum, molybdenum, iridium, or titanium. One electrode 111 is located above the piezoelectric film 113 and is connected to an electrode pad, which is a circuit pattern for applying a drive voltage to the electrode 111. The other electrode 112 is located below the piezoelectric film 113 and is connected to an electrode pad, which is a circuit pattern for applying a drive voltage to the electrode 112.

[0100] The piezoelectric film 113 is made of, for example, lead zirconate titanate (PZT). In addition to lead zirconate titanate, the piezoelectric film 113 can also be made of aluminum nitride (AlN), zinc oxide (ZnO), lead titanate (PbTiO3), or the like.

[0101] The electrode 111 is connected to the wiring 121 through an opening formed in the insulating film 120. An insulating film 122 is provided on the wiring 121. The electrode 111 is electrically connected to an electrode pad through the opening in the insulating film 122. The contact member 118 is formed on the insulating film 122 and on the film support portion 117. In this specification, "electrically connected" includes connection via "something that has some kind of electrical function." Here, "something that has some kind of electrical function" is not particularly limited as long as it enables the exchange of electrical signals between the objects to be connected. For example, "something that has some kind of electrical function" includes electrodes, wiring, switching elements, resistive elements, inductors, capacitive elements, and other elements having various functions.

[0102] The wiring 121 is formed using, for example, a thin film of metal, etc. The insulating films 120 and 122 can be made of, for example, aluminum oxide, etc.

[0103] Membrane 115 is made up of vibrating membrane 116 and membrane support portion 117. Membrane 115 is made up of, for example, silicon (Si). By etching the back surface side of membrane 115, vibrating membrane 116 and membrane support portion 117 are integrally formed.

[0104] Vibrating membrane 116 is made of a thin film and is configured to be displaceable in the film thickness direction, i.e., in the normal direction to vibrating membrane 116 (the Z direction: up and down the plane of the paper in FIG. 21, and the Z direction: perpendicular to the front and back of the paper in FIG. 22). Vibrating membrane 116 has a substantially rectangular shape when observed from a plane parallel to vibrating membrane 116.

[0105] Membrane support part 117 has a rectangular cylindrical inner circumferential surface that forms space (hollow part, cavity) 201. Vibrating membrane 116 is inscribed on one side of the inner circumferential surface of membrane support part 117, and thereby vibrating membrane 116 is supported by membrane support part 117. Vibrating membrane 116 is connected to the upper end side of membrane support part 117.

[0106] Furthermore, membrane support portion 117 has an area that overlaps with the end of piezoelectric element 110, and vibrating membrane 116 has a cantilever shape that protrudes from membrane support portion 117. The tip end of vibrating membrane 116 is configured as a free end. However, without being limited to this, vibrating membrane 116 may have a cantilever shape in which both ends are fixed by membrane support portion 117.

[0107] Substrate 119 is in contact with membrane support portion 117. An opening 119a is formed in the center of substrate 119. In addition, in space 201 surrounded by vibrating membrane 116, membrane support portion 117, and substrate 119, air vibrates due to displacement of vibrating membrane 116, and the air circulates to the outside of transducer 101 through opening 119a. In addition, as shown in FIG. 22, opening 119a preferably has rounded edges. By rounding the edges of opening 119a, stress concentration at the edges can be alleviated. Substrate 119 is made of, for example, silicon (Si). In addition, substrate 119 has a function of limiting the displacement of vibrating membrane 116.

[0108] In transducer 101 configured as described above, piezoelectric element 110 is provided on vibrating membrane 116 of membrane body 115. That is, lower electrode 112, piezoelectric film 113, and upper electrode 111 are laminated in this order on vibrating membrane 116. When drive voltages are applied to paired electrodes 111 and 112, respectively, a potential difference occurs between paired electrodes 111 and 112. This potential difference displaces vibrating membrane 116. Specifically, the tip side of vibrating membrane 116 is displaced so as to bend.

[0109] By repeatedly applying a drive voltage to the pair of electrodes 111 and 112, the vibration membrane 116 alternately repeats displacement toward the space 200 side and displacement toward the space 201 side. The vibration of the vibration membrane 116 causes the air around the vibration membrane 116 to vibrate, and the vibration of the air is output as a sound wave.

[0110] In this embodiment, the transducer 101 has a contact member 118 that limits the displacement of the vibrating membrane 116 by contacting the vibrating membrane 116 or the piezoelectric element 110 when the vibrating membrane 116 is displaced in the film thickness direction. The substrate 119 also has a function of limiting the displacement of the vibrating membrane 116.

[0111] With this configuration, contact member 118 and / or substrate 119 can suppress air leakage and vibrate air efficiently. Furthermore, contact member 118 and / or substrate 119 can limit the displacement of vibrating membrane 116, thereby suppressing excessive displacement of vibrating membrane 116 due to impact or the like. This can suppress the occurrence of breakage, thereby suppressing air leakage and providing a transducer that is resistant to impact or the like.

[0112] The transducer according to this embodiment is not limited to the above-described configuration, and various modifications are possible. Modifications of the transducer according to this embodiment will be described below.

[0113] <First Modification> The configuration of a transducer 101A according to this modified example will be described using Figures 23 and 24. The transducer 101A according to this modified example differs from the transducer 101 shown in Figures 21 and 22 described above in that a wiring 123 is newly provided to connect to wiring 121. The above description will be used to refer to the points common to the transducer 101 shown in Figures 21 and 22 in this modified example, and only the points of difference will be described below.

[0114] The wiring 123 is connected to the wiring 121 through a via provided in the membrane support portion 117. That is, the wiring 123 is electrically connected to the electrode 111 through the wiring 121. This is not limiting, and for example, the wiring 123 may be configured to be electrically connected to the electrode 111 using wiring provided on the outer wall of the membrane body 115. By providing the wiring 123 on the back surface of the substrate 119, surface mounting is possible, and the surface mounting method takes up less space than the wire bonding method, and is therefore suitable for miniaturizing the transducer.

[0115] <Second Modification> The configuration of a transducer 101B according to this modified example will be described using Figure 25. The transducer 101 according to this modified example differs from the transducer 101 shown in Figures 21 and 22 described above in that a filter 124 that covers the openings 118a and 119a is newly provided. The above explanation will be used to refer to the points common to the transducer 101 shown in Figures 21 and 22 in this modified example, and the points of difference will be described below.

[0116] The filter 124 is provided on the upper surface of the contact member 118 so as to close the opening 118a. The filter 124 is provided on the back surface of the substrate 119 so as to close the opening 119a. The filter 124 is formed in a sheet shape and is made of a material that allows air to pass through. The filter 124 may be made of a waterproof and breathable fabric such as a nonwoven fabric or Gore-Tex (registered trademark). The filter 124 may be provided on the lower surface of the contact member 118 or the upper surface of the substrate 119, or may be provided on the side surface of the contact member 118 or the side surface of the membrane support part 117 as in a third modified example described below.

[0117] By providing filter 124, opening 118a and / or opening 119a are blocked by filter 124, which makes it possible to prevent dust, liquid, and the like from entering internal space 200 and space 201. Furthermore, filter 124 is made of a material that allows air to pass through, so air can be maintained circulating through opening 118a and opening 119a.

[0118] <Third Modification> The configuration of transducer 101C according to this modification will be described using Figures 26, 27A, and 27B. Transducer 101C according to this modification differs from transducer 101A of the first modification described above in that abutment member 128 is used instead of abutment member 118, membrane support member 127 is used instead of membrane support member 117, and substrate 129 is used instead of substrate 119. Air in spaces 200 and 201 is circulated to the outside via slits 132 provided in abutment member 128 and slits 133 provided in membrane support member 127 instead of openings 118a and 119a. The above description will be used to refer to the points common to transducer 101A of the first modification in this modification, and only the points of difference will be described below.

[0119] The abutting member 128a can be made of the same material as the abutting member 118. For example, when etching a material to form a groove that will become the space 200, a slit can be formed at the same time to form the abutting member 128. Alternatively, the abutting member 128 can be formed by etching a material to form a groove that will become the space 200, and then etching a part of the inner surface of the groove to form a slit. From the standpoint of the number of steps and cost, it is preferable to simultaneously form the groove that will become the space 200 and the slit using one photomask.

[0120] 27A shows a cross-sectional view of slits 132 in region 130 shown in FIG. 26 as viewed from the air inlet / outlet side (left side of the page). As shown in FIG. 27A, slits 132 provided in abutting member 128 have a comb-like structure. Such a structure can prevent foreign matter (such as dust or liquid) from entering internal space 200 from the outside. Furthermore, slits 132 do not have to have a comb-like structure, and may have, for example, a lattice-like structure, as long as the structure can prevent foreign matter from entering internal space 200 from the outside.

[0121] The membrane support portion 127 can be made of the same material as the membrane support portion 117. In other words, the membrane 115 is composed of the vibrating membrane 116 and the membrane support portion 127. Therefore, by etching the back surface of the membrane 115, the vibrating membrane 116 and the membrane support portion 127 are integrally formed. When etching the back surface of the membrane 115 to form a groove portion that will become the space 201, the membrane support portion 127 can be formed by simultaneously forming a slit. Alternatively, the membrane support portion 127 can be formed by etching the back surface of the membrane 115 to form a groove portion that will become the space 201, and then etching a portion of the inner surface of the groove to form a slit. From the standpoint of the number of processes and costs, it is preferable to simultaneously form the groove portion and the slit that will become the space 201 using one photomask.

[0122] FIG. 27B shows a cross-sectional view of the slit 133 in the region 131 shown in FIG. 26 as viewed from the air inlet / outlet side (the right side of the page). As shown in FIG. 27B, the slit 133 provided in the membrane support part 127 has a comb-like structure. With such a structure, it is possible to prevent foreign matter (such as dust or liquid) from entering the internal space 201 from the outside. Furthermore, the slit 133 does not have to have a comb-like structure, and may have, for example, a lattice-like structure, as long as it is configured to prevent foreign matter from entering the internal space 201 from the outside.

[0123] Furthermore, slit 133 is located in a diagonal direction to slit 132. Specifically, the side surface of membrane support part 127 on which slit 133 is provided is located in a diagonal direction to the side surface of contact member 128 on which slit 132 is provided, across vibrating membrane 116. This structure allows air to flow efficiently in and out of the atmosphere.

[0124] <Fourth Modification> The configuration of transducer 101D according to this modification will be described using Fig. 28. Transducer 101D according to this modification differs from transducer 101A of the first modification described above in that it uses a contact member 138 instead of a contact member 118, and a membrane support member 137 instead of membrane support member 117. The above description will be used to refer to the points common to transducer 101A of the first modification in this modification, and the points of difference will be described below.

[0125] The abutting member 138 can be made of the same material as the abutting member 118. The abutting member 138 has an opening 138a, and the side surface of the abutting member 138 at the opening 138a is formed in a forward tapered shape. This is not limiting, and the side surface of the abutting member 138 at the opening 138a may be formed in a reverse tapered shape. The abutting member 138 also has a reverse tapered side surface 138b that is the abutting surface. By having the side surface 138b, the distance (gap) between the abutting member 138 and the vibrating membrane 116 can be reduced. By reducing the gap, air leakage can be suppressed and the air can be vibrated efficiently.

[0126] The membrane support portion 137 can be made of the same material as the membrane support portion 117. The membrane support portion 137 has a tapered side surface 137a. The membrane body 115 is composed of the vibrating membrane 116 and the membrane support portion 137. Therefore, by etching the back surface side of the membrane body 115, the vibrating membrane 116 and the membrane support portion 137 are integrally formed. The back surface side of the membrane body 115 is etched to form a groove portion that becomes the space 201, and then a part of the inner surface of the groove is etched to form the side surface 137a, thereby forming the membrane support portion 137. By having the side surface 137a, the distance (gap) to the vibrating membrane 116 can be reduced. By reducing the gap, air leakage can be suppressed and the air can be vibrated efficiently.

[0127] <Fifth Modification> The configuration of transducer 101E according to this modification will be described using Figures 29 and 30. Transducer 101E according to this modification differs from transducer 101A of the first modification described above in that it uses abutment member 148 instead of abutment member 118, and uses substrate 139 instead of substrate 119. The above description will be used to refer to the points common to transducer 101A of the first modification in this modification, and only the points of difference will be described below.

[0128] The abutting member 148 can be made of the same material as the abutting member 118. The abutting member 148 has an opening 148a, and through-holes 148b are formed in the opening 148a. The through-holes 148b preferably become smaller as they move away from the vibrating membrane 116. By providing such through-holes 148b, it is possible to prevent foreign matter (such as dust or liquid) from entering the internal space 200 from the outside. Furthermore, it is preferable that the diameter of the through-holes 148b be larger near the tip of the vibrating membrane 116, because this allows the air near the tip of the vibrating membrane 116, where the amount of displacement of the vibrating membrane 116 is large, to vibrate more efficiently. Furthermore, it is preferable that the density of holes of the same diameter near the tip of the vibrating membrane 116 be higher than in other locations near the tip of the vibrating membrane 116, because this allows the air near the tip of the vibrating membrane 116 to vibrate more efficiently.

[0129] The substrate 139 can be made of the same material as the substrate 119. The substrate 139 has an opening 139a, and through-holes 139b are formed in the opening 139a. The through-holes 139b preferably become smaller with increasing distance from the vibrating membrane 116. By providing such through-holes 139b, it is possible to prevent foreign matter (such as dust or liquid) from entering the internal space 201 from the outside. Furthermore, it is preferable to increase the diameter of the through-holes 139b near the tip of the vibrating membrane 116, because this allows the air near the tip of the vibrating membrane 116, where the amount of displacement of the vibrating membrane 116, to vibrate more efficiently. Furthermore, it is preferable to increase the density of holes of the same diameter near the tip of the vibrating membrane 116 compared to other locations near the tip of the vibrating membrane 116, because this allows the air near the tip of the vibrating membrane 116 to vibrate more efficiently.

[0130] As mentioned above, although several modifications have been described, the descriptions and drawings forming part of the disclosure should be understood as illustrative and not restrictive. From this disclosure, various alternative modifications and operating techniques will become apparent to those skilled in the art.

[0131] (Sixth embodiment) An electronic device according to this embodiment will be described. The electronic device according to this embodiment has a speaker unit and a housing that houses the speaker unit. An example of the electronic device is an earphone. Earphone 150 shown in FIG. 31A has earpiece 151 and housing 152.

[0132] 31B is a diagram showing earphone 150 with earpiece 151 removed, illustrating the shape of housing 152. Housing 152 is cylindrical with a bottom, and has tubular portion 152a and bottom portion 152b that contacts tubular portion 152a. Speaker units are disposed in part of tubular portion 152a and part of bottom portion 152b. The arrangement of housing 152 and the speaker unit (mounting of the speaker unit) will be described below.

[0133] <Implementation example 1> As shown in Fig. 32, the speaker unit (transducer 101) has a configuration in which a film 115 and a contact member 118 are provided on a substrate 119. Ventilation holes (specifically, openings 118a and 119a shown in Fig. 33) are provided in the film thickness direction (direction indicated by the arrow in the figure) of the transducer 101 (substrate 119, film 115, and abutment member 118).

[0134] 33 is a cross-sectional view of an earphone in which transducer 101 is mounted on housing 152. Substrate 119 is disposed on part of tubular portion 152a and part of bottom portion 152b, and membrane 115 and abutment member 118 are provided on substrate 119. Substrate 119 has opening 119a, and abutment member 118 has opening 118a. Membrane 115 is composed of a vibrating membrane and a membrane support portion. Bottom portion 152b is separated from tubular portion 152a via transducer 101, and the space in bottom portion 152b communicates with the outside of housing 152 via openings 118a and 119a. The transducer 101 in this implementation example can be, for example, the transducer 101 according to the first embodiment shown in Figures 21 and 22, and the space at the bottom 152b is connected to the outside of the housing 152 via the opening 118a, the space 200, the space 201, and the opening 119a.

[0135] By using a structure in which the cylindrical portion 152a and the bottom portion 152b are separated via the transducer 101, the airflow between the cylindrical portion 152a and the bottom portion 152b is blocked. This allows the space inside the housing 152 to be used to mount other devices, a battery, etc., and the housing 152 can be made smaller.

[0136] <Implementation example 2> As shown in Fig. 34, the speaker unit (transducer 101) has a configuration in which a membrane 115 and an abutment member 128 are provided on a substrate 129. Ventilation holes (specifically, slits 132 and 133 shown in Fig. 35) are provided on the side of the transducer 101 (substrate 129, membrane 115, and abutment member 128). In other words, air flows in the direction shown by the arrows in the figure.

[0137] 35 is a cross-sectional view of an earphone in which transducer 101 is mounted on housing 152. Substrate 129 is disposed on part of tubular portion 152a and part of bottom portion 152b, and membrane 115 and abutment member 128 are provided on substrate 129. Membrane 115 is composed of a vibrating membrane and a membrane support portion. Abutment member 128 has slit 132, and the membrane support portion of membrane 115 has slit 133. Bottom portion 152b is separated from tubular portion 152a via transducer 101, and the space in bottom portion 152b communicates with the outside of housing 152 via slits 132 and 133. The transducer 101 in this implementation example can be, for example, the transducer 101C according to the third modified example shown in FIG. 26, and the space of the bottom 152b is connected to the outside of the housing 152 via the slit 132, the space 200, the space 201, and the slit 133.

[0138] By using a structure in which the cylindrical portion 152a and the bottom portion 152b are separated via the transducer 101, the airflow between the cylindrical portion 152a and the bottom portion 152b is blocked. This allows the space inside the housing 152 to be used to mount other devices, a battery, etc., and the housing 152 can be made smaller.

[0139] (Other embodiments) Although several embodiments have been described above, the descriptions and drawings forming part of the disclosure are illustrative and should not be understood as limiting. From this disclosure, various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art.

[0140] For example, the transducer may be used to receive sound waves in addition to transmitting sound waves.Furthermore, the transducer may be used to transmit or receive ultrasonic waves, not just sound waves. [Explanation of symbols]

[0141] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 101, 101A, 101B, 101C, 101D, 101E Transducers 2, 132, 133 Slits 10, 110 Piezoelectric element 11, 12, 111, 112 electrodes 11a, 12a electrode pads 13, 113 Piezoelectric film 14 Piezoelectric slit 15, 115 membrane body 16, 16a, 116 Vibration membrane 17, 117, 127, 137 Membrane support part 18, 18a, 18b, 18c, 18d Buffer layer 19 Recess 20 Hollow part 21 Connecting part 22, 24 First Area 23, 25 Second Area 118, 128, 138, 148 Contact members 118a, 119a, 138a, 139a, 148a opening 119, 129, 139 boards 120, 122 insulating film 121, 123 wiring 124 filters 130, 131 area 137a, 138b side 139b, 148b through hole 150 earphones 151 earpiece 152 cabinet 152a Cylinder part 152b bottom 200, 201 space

Claims

1. a piezoelectric element including a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes; a membrane body including a membrane support part having a hollow part, and a vibration membrane connected to the membrane support part and displaceable in a thickness direction, and the piezoelectric element is laminated on the vibration membrane; a contact member that limits the displacement of the vibration membrane, A transducer, wherein an end of the piezoelectric element has an area that overlaps with the membrane support portion.

2. The transducer according to claim 1 , wherein the piezoelectric element and the vibration membrane are disposed between the hollow portion and the contact member.

3. the abutment member has a first opening; 3. The transducer of claim 1, wherein the first opening has a rounded edge.

4. the abutment member has a first opening; The transducer according to any one of claims 1 to 3, further comprising a first filter covering the first opening.

5. The transducer according to claim 1 or 2, wherein the abutment member has a plurality of first through holes.

6. The transducer according to claim 5 , wherein the first through-holes become smaller in size as they move away from the vibration membrane.

7. 7. The transducer according to claim 1, wherein a second side surface of said contact member facing said first side surface of said contact member on said end side is formed in a tapered shape.

8. The transducer according to any one of claims 1 to 7, wherein the first side surface of the abutting member has a first slit on the end side.

9. The transducer of claim 8 , wherein the first slit is a comb-like structure.

10. Further, a substrate is provided in contact with the film body, 10. The transducer according to claim 1, wherein the film body is sandwiched between the substrate and the abutting member.

11. the substrate has a second opening; The transducer of claim 10 , wherein the second opening has a rounded edge.

12. the substrate has a second opening; 12. The transducer of claim 10 or 11, further comprising a second filter covering the second opening.

13. The transducer according to any one of claims 10 to 12, wherein the substrate has a plurality of second through holes.

14. The transducer of claim 13 , wherein the second through-holes become smaller in size as they move away from the vibration membrane.

15. The transducer according to any one of claims 10 to 14, wherein the first side surface of the membrane support portion is tapered.

16. The transducer according to any one of claims 10 to 15, wherein the first side surface of the membrane support portion has a second slit on a side diagonally opposite to the end portion.

17. 17. The transducer of claim 16, wherein the second slit is a comb-like structure.

18. The transducer according to any one of claims 1 to 17, further comprising a wiring electrically connected to one of the pair of electrodes.

19. The transducer of claim 18 , wherein the wiring is electrically connected to one of the pair of electrodes through a via provided in the membrane support portion.

20. a speaker unit including a substrate; a cylindrical housing with a bottom that houses the speaker unit therein; the housing has a cylindrical portion and a bottom portion in contact with the cylindrical portion, the substrate is disposed on a part of the cylindrical portion and a part of the bottom; the bottom portion is separated from the cylindrical portion via the speaker unit, The speaker unit has a vent hole in the thickness direction of the film, The electronic device is configured so that the space at the bottom communicates with the outside of the housing through the ventilation hole.

21. a speaker unit including a substrate; a cylindrical housing with a bottom that houses the speaker unit therein; the housing has a cylindrical portion and a bottom portion in contact with the cylindrical portion, the substrate is disposed on a part of the cylindrical portion and a part of the bottom; the bottom portion is separated from the cylindrical portion via the speaker unit, The speaker unit has a vent hole on a side surface, The electronic device is configured so that the space at the bottom communicates with the outside of the housing through the ventilation hole.

22. The speaker unit includes a transducer; The transducer comprises: a piezoelectric element including a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes; a membrane body including a membrane support part having a hollow part, and a vibration membrane connected to the membrane support part and displaceable in a thickness direction, and the piezoelectric element is laminated on the vibration membrane; a contact member that limits the displacement of the vibration membrane, 22. The electronic device according to claim 20, wherein an end of the piezoelectric element has an area that overlaps with the membrane support portion.

Images