Piezoelectric sound generating component

Abstract

The present application relates to a piezoelectric sound emitting component. The piezoelectric sound emitting component (1) is provided with a piezoelectric vibration plate (2) and a housing (5) accommodating the piezoelectric vibration plate (2), a peripheral edge portion (15) of the vibration plate (10) has a first peripheral edge portion (13) fixed to the housing (5) and a second peripheral edge portion (12) movable relative to the housing (5), the housing (5) has a stepped portion (34) provided at a position corresponding to the second peripheral edge portion (12) in a thickness direction of the vibration plate (10), and a gap (P) is formed between the stepped portion (34) and the second peripheral edge portion (12).

Description

Technical Field

[0001] This invention relates to piezoelectric sound-generating components. Background Technology

[0002] Piezoelectric sound-generating components are widely used in electronic devices, home appliances, mobile phones, and other electronic products as piezoelectric buzzers or piezoelectric receivers that emit alarm or action sounds. Such piezoelectric sound-generating components require high sound conversion efficiency.

[0003] For example, Patent Document 1 discloses a piezoelectric sound-generating component that has the characteristics of large displacement and high sound pressure by providing a slit in the vibrating plate, thereby suppressing air convection in the air chambers above and below the vibrating plate without sealing them.

[0004] Patent Document 1: Japanese Patent Application No. 2019-151732

[0005] However, to achieve greater displacement, high sound pressure as a good sound pressure characteristic, and low-frequency sound as an easier-to-hear sound, the vibrating plate of the piezoelectric sound-generating component needs to be thinner. Furthermore, the slit shown in Patent Document 1 is a structure that extends through the vibrating plate along its thickness direction. When a slit is formed in a thin vibrating plate, the width of the slit needs to be very narrow to maintain the effect of suppressing air convection based on the slit. However, such a very narrow slit is difficult to manufacture and prone to manufacturing deviations. In addition, due to the vibration of the vibrating plate, the slit may deform, causing its width to increase. As a result, the sound pressure characteristics of the piezoelectric sound-generating component become unstable. Summary of the Invention

[0006] The present invention was made in view of the following circumstances, and is able to provide a piezoelectric sound generating component that can use a simple structure, maintain sound conversion efficiency, and obtain good sound pressure characteristics.

[0007] One aspect of the piezoelectric sound-generating component of the present invention includes: a piezoelectric vibrating plate having a vibrating plate and a piezoelectric body, the vibrating plate having a central portion and a peripheral portion surrounding the central portion, the piezoelectric body being disposed in the central portion; and a housing having an internal space and housing the piezoelectric vibrating plate therein, the peripheral portion of the vibrating plate having a first peripheral portion fixed to the housing and a second peripheral portion movable relative to the housing, the housing having a stepped portion disposed in the thickness direction of the vibrating plate at a position corresponding to the second peripheral portion, and a gap being formed between the stepped portion and the second peripheral portion.

[0008] According to the present invention, a piezoelectric sound-generating component can be provided, which can maintain sound conversion efficiency and obtain good sound pressure characteristics using a simple structure. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view showing the structure of the piezoelectric sound-generating component according to the first embodiment.

[0010] Figure 2 yes Figure 1 Sectional view along line II-II.

[0011] Figure 3 This is a diagram showing the structure of the housing according to the first embodiment.

[0012] Figure 4 yes Figure 2 An enlarged view of part A.

[0013] Figure 5 This is a graph showing the relationship between the width of the gap and the sound pressure attenuation in the first embodiment.

[0014] Figure 6 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the second embodiment.

[0015] Figure 7 This is a cross-sectional view showing the state of each structure of the piezoelectric sound-generating component when the piezoelectric vibrating plate according to the second embodiment vibrates.

[0016] Figure 8 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the third embodiment.

[0017] Figure 9 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the fourth embodiment.

[0018] Figure 10 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the fifth embodiment.

[0019] Figure 11 This is an exploded perspective view showing the structure of the piezoelectric sound-generating component according to the sixth embodiment.

[0020] Figure 12 This is a diagram showing the structure of the piezoelectric vibrating plate involved in the comparative example.

[0021] Figure 13 This is a diagram showing the vibration state of the piezoelectric vibrating plate involved in the comparative example.

[0022] Figure 14 This is a graph showing the relationship between the width of the slit involved in the comparative example and the sound pressure attenuation. Detailed Implementation

[0023] The embodiments of the present invention will now be described. In the following drawings, the same or similar structural elements are indicated by the same or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of the parts are schematic and should not be construed as limiting the technical scope of the present invention to these embodiments.

[0024] [First Implementation Method]

[0025] <Piezoelectric Sound Generating Component 1>

[0026] First, refer to Figure 1 and Figure 2 An overview of the piezoelectric sound-generating component 1 according to the first embodiment will be described. Figure 1 This is an exploded perspective view showing the structure of the piezoelectric sound-generating component 1 according to the first embodiment. Figure 2 yes Figure 1 Sectional view along line II-II. In the following description, Figure 2 The state of the piezoelectric sound-generating component 1 shown is called the "assembly state".

[0027] Piezoelectric sound-generating component 1 is an example of a pin-type sound-generating component. For example... Figure 1 As shown, the piezoelectric sound-generating component 1 includes a piezoelectric vibrating plate 2 and a housing 5 for housing the piezoelectric vibrating plate 2. The housing 5 has a housing body 3 with an opening and a cover 4 for closing the opening of the housing body 3. Additionally, as... Figure 2 As shown, the housing 5 has an internal space 30 surrounded by the housing body 3 and the cover 4, and a stepped portion 34 located in the internal space 30 and disposed on the peripheral wall of the housing 5. The stepped portion 34 has a first stepped portion 341 disposed on the housing body 3 and a second stepped portion 342 disposed on the cover 4.

[0028] In the assembled state, the piezoelectric vibrating plate 2 is housed in the internal space 30, so that part of it is clamped and fixed to the housing 5 by the housing body 3 and the cover 4, while the other part is inserted into the stepped portion 34 and is movable relative to the housing 5. In this case, a gap P is formed between the stepped portion 34 and the other part of the piezoelectric vibrating plate 2 inserted into the stepped portion 34. In addition, in this case, the two pin terminals 50 provided on the cover 4 are electrically connected to the piezoelectric vibrating plate 2. In this way, the piezoelectric vibrating plate 2 vibrates in the internal space 30 by means of the AC voltage applied from the two pin terminals 50. Figure 2 It vibrates back and forth as shown by the dotted line to produce sound (ringing).

[0029] <Detailed information about piezoelectric sound-generating component 1>

[0030] Next, refer to Figures 1 to 4 The detailed structure of each component of the piezoelectric sound-generating component 1 is explained. Figure 3 This is a diagram showing the structure of the housing 5 according to the first embodiment. Figure 4 yes Figure 2 An enlarged view of part A.

[0031] (Piezoelectric vibrating plate 2)

[0032] The piezoelectric vibrating plate 2 is formed into a thin plate shape. For example... Figure 1 and Figure 2 As shown, the piezoelectric vibrating plate 2 has a vibrating plate 10 and a piezoelectric element 20 disposed on the vibrating plate 10.

[0033] The vibrating plate 10 is formed in a sheet shape. The top view of the main surface of the vibrating plate 10 is square. Alternatively, the top view of the main surface of the vibrating plate 10 can also be circular or rectangular, etc. The thickness of the vibrating plate 10 is, for example, 0.05 mm. Figure 1 In the example shown, no slits or cuts are formed in the vibrating plate 10 that extend through the vibrating plate 10 in the thickness direction.

[0034] Furthermore, the vibrating plate 10 is made of a material with good electrical conductivity and spring elasticity, such as a metal with an elastic modulus of 1 GPa or higher. In particular, the vibrating plate 10 is preferably made of alloy 42, SUS (stainless steel), brass, phosphor bronze, etc. In addition, the vibrating plate 10 may also be made of resin-based materials and composite materials such as glass epoxy resin with an elastic modulus of 1 GPa or higher.

[0035] In addition, such as Figure 2 As shown, the vibrating plate 10 has a first main surface 111, a second main surface 112, and a side surface 113. In the assembled state, the first main surface 111 faces a first direction, and the second main surface 112 faces a second direction. In addition, the second main surface 112 is electrically connected to one of the two pin terminals 50 of the cover 4.

[0036] Furthermore, the vibrating plate 10 has a central portion 11 located at the center of the vibrating plate 10 and a peripheral portion 15 located around the central portion 11 in the main surface direction. In the assembled state, a piezoelectric element 20 is provided in the central portion 11. Additionally, as... Figure 2 As shown, the central portion 11 and a part of the peripheral portion 15 (the second peripheral portion 12 described later) together constitute the reciprocating vibration portion V of the piezoelectric vibrating plate 2.

[0037] like Figure 1 As shown, the peripheral portion 15 has a first peripheral portion 13 and a second peripheral portion 12. The first peripheral portion 13 is the four corners of the vibrating plate 10. The second peripheral portion 12 is the portion of the periphery of the vibrating plate 10 other than the four corners. In other words, the second peripheral portion 12 is the portion corresponding to the four sides (excluding the corners) of the vibrating plate 10.

[0038] The first peripheral portion 13 is an example of a structure in which the piezoelectric vibrating plate 2 is fixed to the housing 5. In the assembled state, the first peripheral portion 13 is held between the housing body 3 and the cover 4 and fixed relative to the housing 5. In this way, the piezoelectric vibrating plate 2 is mounted to the housing 5. In addition, in this case, the second peripheral portion 12 is configured to be movable relative to the housing 5.

[0039] The second peripheral portion 12 is an example of a structure that, together with the stepped portion 34 of the housing body 3 (described later), suppresses air convection on both sides of the piezoelectric vibrating plate 2 in the thickness direction. In the assembled state, the second peripheral portion 12 is inserted into the stepped portion 34 without contacting it. Furthermore, details regarding the configuration of the second peripheral portion 12 and the stepped portion 34 will be explained in the "Detailed Description of the Stepped Portion 34" section (described later).

[0040] The piezoelectric element 20 is formed in the shape of a sheet. The piezoelectric element 20 is configured as a pair of electrodes holding a piezoelectric plate. The top view of the main surface of the piezoelectric element 20 is circular. The piezoelectric element 20 is attached to the second main surface 112 of the central portion 11 of the vibrating plate 10 by means of an adhesive.

[0041] In the assembled state, the electrode on the first direction side of the piezoelectric element 20 is electrically connected to one of the two pin terminals 50 of the cover 4 via the second main surface 112 of the vibrating plate 10. The electrode on the second direction side of the piezoelectric element 20 is electrically connected to the other of the two pin terminals 50 of the cover 4.

[0042] (Main body of the shell 3)

[0043] The main body 3 of the casing is box-shaped. Furthermore, the main body 3 is made of insulating materials such as ceramics and resin. Figures 1 to 3 As shown, the housing body 3 has a first top wall portion 31, a first peripheral wall portion 32 disposed at the end of the first top wall portion 31, a first pressing portion 33 disposed at the four corners of the first peripheral wall portion 32, and a first step portion 341 disposed on the first peripheral wall portion 32.

[0044] The first top wall portion 31 is formed in the shape of a thin plate. The top view of the main surface of the first top wall portion 31 is square. For example... Figure 2 As shown, the first top wall portion 31 has a top wall main surface 311 and a top wall main surface 312 located on both sides in the thickness direction. A sound emission hole 313 is provided in the center of the first top wall portion 31. The sound emission hole 313 extends through the first top wall portion 31 in the thickness direction, connecting the interior of the housing body 3 with the exterior. Thus, in the assembled state, the sound emission hole 313 can release the sound generated by the reciprocating vibration of the piezoelectric vibrating plate 2 to the exterior of the housing 5.

[0045] The first circumferential wall portion 32 is formed into a frame shape. For example... Figure 2 and Figure 3As shown, the first peripheral wall portion 32 has an inner peripheral surface 321, an outer peripheral surface 322, and an opening 323 provided at one end of the first peripheral wall portion 32. The inner peripheral surface 321 is composed of four planes. Figure 2 As shown, in the assembled state, the portion of the inner peripheral surface 321 located on the side closer to the first direction than the piezoelectric vibrating plate 2, together with the main surface 312 of the top wall and the piezoelectric vibrating plate 2, constitutes the acoustic space 301 of the internal space 30 located on the first direction side.

[0046] The first pressing part 33 is a protruding structure formed on the four corner sides of the first peripheral wall part 32. In addition, the first pressing part 33 extends along the height direction of the first peripheral wall part 32. In the assembled state, the first pressing part 33, together with the second pressing part 43 of the cover 4 (described later), clamps the first peripheral edge part 13 of the piezoelectric vibrating plate 2, thereby fixing the piezoelectric vibrating plate 2 to the housing 5.

[0047] The first step portion 341 is a protrusion provided on the side of the opening 323 of the first peripheral wall portion 32, and is formed on each of the four planes of the inner peripheral surface 321. In the assembled state, the first step portion 341 is provided at a position corresponding to the second peripheral edge portion 12 of the piezoelectric vibrating plate 2. Specifically, the first step portion 341 is provided on the side of the first main surface 111 of the second peripheral edge portion 12. In addition, in this case, the first step portion 341 does not contact the second peripheral edge portion 12. That is, as Figure 4 As shown, a gap is formed between the first stepped portion 341 and the second peripheral portion 12. Further details regarding the first stepped portion 341 will be described later.

[0048] (Cover 4)

[0049] like Figure 1 and Figure 3 As shown, the cover 4 has a cover body 40 and two pin terminals 50 disposed on the cover body 40.

[0050] The cover body 40 is box-shaped. Furthermore, the cover body 40 is made of insulating materials such as ceramics or resin. Figure 1 and Figure 3 As shown, the cover 4 has a second top wall portion 41, a second peripheral wall portion 42 disposed at the end of the second top wall portion 41, a second pressing portion 43 disposed at the four corners of the second top wall portion 41, a fixing portion 44 disposed on the second top wall portion 41, and a second step portion 342 disposed on the second peripheral wall portion 42.

[0051] The second top wall portion 41 is formed into a thin plate shape. The top view of the main surface of the second top wall portion 41 is square. For example... Figure 2 As shown, the second top wall portion 41 has a top wall main surface 411 and a top wall main surface 412 located on both sides in the thickness direction. In addition, the second top wall portion 41 has a through hole (not shown) that extends through the second top wall portion 41 in the thickness direction.

[0052] The second wall portion 42 forms a frame shape. For example... Figure 2 and Figure 3 As shown, the second peripheral wall portion 42 has an inner peripheral surface 421, an outer peripheral surface 422, and an opening 423 provided at one end of the second peripheral wall portion 42. The inner peripheral surface 421 is composed of four planes. Figure 2 As shown, in the assembled state, the inner peripheral surface 421, together with the top wall main surface 411 and the piezoelectric resonator 2, constitute the acoustic space 302 located on the second direction side of the internal space 30.

[0053] The second pressing part 43 is a protrusion formed on the four corner sides of the second peripheral wall part 42. In addition, the second pressing part 43 extends along the height direction of the second peripheral wall part 42. In the assembled state, the second pressing part 43, together with the first pressing part 33 of the housing body 3, clamps the first peripheral edge 13 of the piezoelectric vibrating plate 2, thereby fixing the piezoelectric vibrating plate 2 to the housing 5.

[0054] The fixing part 44 is a protruding structure provided on the main surface 411 of the top wall of the second top wall part 41. In the assembled state, the fixing part 44, together with the through hole formed in the second top wall part 41, can fix the two pin terminals 50 to the second top wall part 41. In addition, the fixing part 44 can maintain the contact posture between the two pin terminals 50 and the piezoelectric vibrating plate 2.

[0055] The second step portion 342 is a protrusion provided on the side of the opening 423 of the second peripheral wall portion 42, and is formed on each of the four planes of the inner peripheral surface 421. In the assembled state, the second step portion 342 is provided at a position corresponding to the second peripheral edge portion 12 of the piezoelectric vibrating plate 2. Specifically, the second step portion 342 is positioned opposite the first step portion 341 to the second main surface 112 side of the second peripheral edge portion 12. In this case, the second step portion 342 does not contact the second peripheral edge portion 12. That is, as Figure 4 As shown, a gap is formed between the second step portion 342 and the second peripheral portion 12. Further details regarding the second step portion 342 will be described later.

[0056] The two lead terminals 50 are flexible components formed by bending wires. Furthermore, the wires are, for example, phosphor bronze wires with a Sn plating on their surface. The two lead terminals 50 are fixed to the cover 4 via a through hole and a fixing part 44 provided in the second top wall portion 41 of the cover 4.

[0057] In the assembled state, one of the two pin terminals 50 is electrically connected to the electrode on the first direction side of the piezoelectric body 20 via the second main surface 112 of the vibrating plate 10 of the piezoelectric vibrating plate 2. The other of the two pin terminals 50 is electrically connected to the electrode on the second direction side of the piezoelectric body 20. In this way, the two pin terminals 50 can apply an alternating voltage to a pair of electrodes of the piezoelectric body 20 of the piezoelectric vibrating plate 2.

[0058] <Details of Step 34>

[0059] Next, refer to Figure 4 The details of the step portion 34 will be explained. Specifically, after explaining the structure of the step portion 34, the arrangement relationship between the structure of the step portion 34 and the second peripheral portion 12 will be explained.

[0060] like Figure 4 As shown, the first step portion 341 and the second step portion 342 constituting the step portion 34 have the same shape. In addition, the distance between the first step portion 341 and the second step portion 342 is greater than the thickness of the second peripheral portion 12.

[0061] Specifically, such as Figure 4 As shown, the first step portion 341 has a first step surface 343 facing the second step portion 342, and the second step portion 342 has a second step surface 344 facing the first step portion 341. The first step surface 343 and the second step surface 344 are connected by an inner peripheral surface 321. In the assembled state, each of the first step surface 343, the second step surface 344, and the inner peripheral surface 321 corresponds to a facing surface that opposes each of the first main surface 111, the second main surface 112, and the side surface 113 of the second peripheral edge portion 12. In addition, the first step surface 343, the second step surface 344, and the inner peripheral surface 321, together with the first main surface 111, the second main surface 112, and the side surface 113, form the wall of the gap P.

[0062] In addition, such as Figure 4 As shown, in the thickness direction of the vibrating plate 10, a first gap P1 is formed between the first step surface 343 of the first step portion 341 and the first main surface 111 of the second peripheral portion 12, and a third gap P3 is formed between the second step surface 344 of the second step portion 342 and the second main surface 112 of the second peripheral portion 12. In the main surface direction of the vibrating plate 10, a second gap P2 is formed between the inner peripheral surface 321 of the first peripheral wall portion 32 and the side surface 113 of the second peripheral portion 12. The second gap P2 intersects with the first gap P1 and the third gap P3.

[0063] Furthermore, in the thickness direction of the vibrating plate 10, the width dimension of the first gap P1 is H1, and the width dimension of the third gap P3 is H3. In the main surface direction of the vibrating plate 10, the length dimension of the first gap P1 and the length dimension of the third gap P3 are the length L1 of the first step portion 341 (or the second step portion 342) in the main surface direction of the vibrating plate 10. In the main surface direction of the vibrating plate 10, the width dimension of the second gap P2 is H2. Hereinafter, these dimensions will be referred to as "width dimension H1", "width dimension H2", "width dimension H3" and "length dimension L1".

[0064] Here, the width dimension H1 is preferably 0.35 mm or less. The width dimension H1 in the first embodiment is, for example, 0.35 mm. The width dimension H3 can be formed to be larger than the width dimension H1. The width dimension H3 is, for example, 0.50 mm. Furthermore, the width dimension H3 can also be formed to be the same as or smaller than the width dimension H1. The width dimension H2 can be formed in the same way as the width dimension H3. The length dimension L1 is formed to be larger than the width dimension H1. Additionally, the length dimension L1 is preferably 0.50 mm or more. The length dimension L1 in the first embodiment is, for example, 0.80 mm.

[0065] Furthermore, while the above description states that the first gap P1 is the gap with the smallest width dimension (width dimension H1 is 0.35 mm or less), it is not limited to the structure described above. For example, any one of the width dimensions H1, H2, and H3 can be 0.35 mm or less. Alternatively, any two or all three of the width dimensions H1, H2, and H3 can be 0.35 mm or less. Additionally, the length dimension L1 and the width dimension H1 (or H2) have a relationship where the length dimension L1 becomes shorter as the width dimension H1 (or H2) becomes smaller.

[0066] Thus, the stepped portion 34 and the second peripheral portion 12, which are arranged separately from each other, constitute a first gap P1, a second gap P2, and a third gap P3. In other words, the first gap P1, the second gap P2, and the third gap P3, which have the above-described dimensional characteristics, constitute a U-shaped gap P existing between the stepped portion 34 and the second peripheral portion 12. The gap P connects the acoustic spaces 301 and 302 located on both sides of the piezoelectric resonator 2 in the thickness direction. On the other hand, when the piezoelectric resonator 2 vibrates, almost no convection occurs between the air in the acoustic space 301 and the air in the acoustic space 302, thanks to the gap P.

[0067] <The effect of gap P>

[0068] Next, the effect of the gap P according to the first embodiment will be explained in detail. In the following explanation, refer to Figure 2 , Figure 4 , Figure 5 , Figures 12 to 14 After explaining the principle of suppressing air convection based on the gap P involved in the first embodiment, and... Figure 12 and Figure 13 The comparative examples shown compare the structures of the piezoelectric sound-generating components that suppress air convection, and the effect of the gap P involved in the first embodiment is explained. Figure 5 This is a graph showing the relationship between the width dimension H1 of the first gap P1 involved in the first embodiment and the sound pressure attenuation. Figure 12 This is a diagram showing the structure of the piezoelectric vibrating plate 200 involved in the comparative example. Figure 13 This is a diagram showing the vibration state of the piezoelectric vibrating plate 200 involved in the comparative example. Figure 14 This is a graph showing the relationship between the width h of the slit 130 involved in the comparative example and the sound pressure attenuation.

[0069] (The principle of suppressing air convection)

[0070] First, the principle of the air convection suppression effect based on the gap P according to the first embodiment will be explained. Furthermore, the principle of air convection suppression according to the comparative example is the same as the principle of air convection suppression according to the first embodiment.

[0071] Air exists in the void P. Under normal temperature and pressure conditions (hereinafter referred to as the "normal state"), air is a low-viscosity substance with a viscosity μ of approximately 0.018 mPa·s. When the piezoelectric vibrating plate 2 is not vibrating, the air existing in the void P is not subjected to external force, and its viscosity is low under normal conditions.

[0072] In contrast, when the piezoelectric vibrating plate 2 reciprocates at high speed (e.g., 2 kHz to 10 kHz), shear stress (frictional stress) τ is generated on the air present in the gap P. In other words, frictional stress τ is generated between the air present in the gap P and the wall of the gap P.

[0073] In this case, the actual viscosity μ of the air hardly changes, but due to the large frictional stress τ, the air is difficult to flow relative to the wall of the void P. Therefore, the air present in the void P can be considered to have the same properties as a highly viscous substance. As a result, the air with properties similar to high viscosity closes the void P, suppressing the convection between the air in the acoustic space 301 and the air in the acoustic space 302.

[0074] (The effect of gap P)

[0075] Next, the effect of the gap P in the first embodiment will be explained by comparing it with the structure of the piezoelectric sound-generating component that suppresses air convection in the comparative example.

[0076] Before explaining the effect of the gap P involved in the first embodiment, firstly, refer to... Figure 12 and Figure 13 The structure of the piezoelectric vibrating plate 200 involved in the comparative example will be briefly described.

[0077] like Figure 12 As shown, the piezoelectric vibrating plate 200 of the comparative example includes a vibrating plate 100 and a piezoelectric element 150 disposed on the vibrating plate 100. The vibrating plate 100 has the same shape and thickness as the vibrating plate 10 of the first embodiment. On the other hand, the vibrating plate 100 has a structure that the vibrating plate 10 of the first embodiment does not have, namely, a slit 130.

[0078] The slit 130 is a structure that suppresses the convection between the air present in the acoustic space 3010 and the air present in the acoustic space 3020 on both sides of the piezoelectric vibrating plate 200 of the piezoelectric sound-generating component involved in the comparative example in the thickness direction. Figure 13 As shown, the slit 130 extends through the vibrating plate 100 along its thickness direction. The width h of the slit 130 is 0.10 mm, and the length l of the slit 130 (i.e., the thickness of the vibrating plate 100) is 0.05 mm. In contrast, the narrowest gap P in the first embodiment, namely the first gap P1, has a width H1 of 0.35 mm and a length L1 of 0.80 mm.

[0079] Thus, as Figure 5 and Figure 14 As shown, if the piezoelectric vibrating plate 2 of the piezoelectric sound-generating component 1 according to the first embodiment and the piezoelectric vibrating plate 200 of the piezoelectric sound-generating component according to the comparative example vibrate and generate sound under the same conditions, i.e., based on the same temperature, air pressure, and vibration speed, then both the first gap P1 according to the first embodiment and the slit 130 according to the comparative example can suppress the sound pressure attenuation to "-15dB". That is, the first gap P1 according to the first embodiment can suppress air convection to the same extent as the slit 130 according to the comparative example. Therefore, by employing the first gap P1 according to the first embodiment, the sound conversion efficiency of the piezoelectric sound-generating component 1 can be maintained.

[0080] On the other hand, in this case, the width dimension H1 (0.35 mm) of the first gap P1 involved in the first embodiment is 3.5 times the width dimension h (0.10 mm) of the slit 130 involved in the comparative example. Here, generally, the larger the width dimension of the gap or slit, the less likely the air in the gap or slit is to produce properties similar to high viscosity. However, by forming the length dimension L1 of the first gap P1 to be relatively long, the first embodiment can achieve properties similar to high viscosity even if the width dimension H1 is formed to be relatively large. In addition, in order to form the length dimension L1 of the first gap P1 to be relatively long, the first embodiment forms the length direction of the first gap P1 along the main surface direction of the piezoelectric vibrating plate 2.

[0081] Thus, by employing a first gap P1 along the main surface direction of the piezoelectric vibrating plate 2, the length limitation of the gap along the thickness direction of the vibrating plate 100, as in the slit 130 of the comparative example, can be eliminated; that is, the limitation that only a length the same as the thickness of the vibrating plate 100 can be formed. Therefore, compared to the slit 130 of the comparative example, in the first embodiment, a first gap P1 with a length dimension L1 (0.80 mm) that is 16 times the length dimension l (0.05 mm) of the slit 130 can be formed. Moreover, the width dimension H1 of the first gap P1 in the first embodiment can also be formed to be larger. As a result, compared to the smaller width dimension h (0.10 mm) of the slit 130 of the comparative example, when a larger width dimension H1 (0.35 mm) is adopted in the first embodiment, even if there is a slight deviation in the arrangement of the piezoelectric vibrating plate 2, the impact on the completion of the width dimension H1 is small. Therefore, the deviation of the sound pressure characteristics of the piezoelectric sound-generating component 1 can be reduced.

[0082] Furthermore, the first gap P1 is formed by the second peripheral edge 12 of the vibrating plate 10 and the first stepped portion 341 of the stepped portion 34. Therefore, it is not necessary to cut a slit in the vibrating plate 10 as in the slit 130 of the comparative example. As a result, compared with the case of forming a slit 130 in the comparative example, the structure of the piezoelectric vibrating plate 2 according to the first embodiment is simpler, and the construction process of the piezoelectric vibrating plate 2 is also simpler. Therefore, the manufacturing time and cost of the piezoelectric vibrating plate 2 and the piezoelectric sound-generating component 1 can be reduced. In addition, since no slit is formed in the piezoelectric vibrating plate 2, the strength of the piezoelectric vibrating plate 2 can be improved.

[0083] Furthermore, in the comparative example, due to the deformation of the vibrating plate 10 caused by the vibration of the piezoelectric vibrating plate 200 (see reference). Figure 13The deformation of the slit 130 (as shown by the dotted line) causes the slit 130 to deform, increasing its width and reducing its air convection suppression function. In contrast, in the first embodiment, no slit is formed in the piezoelectric vibrating plate 2, thus avoiding the impact of slit 130 deformation on the air convection suppression function as described in the comparative example. Furthermore, gaps, namely a first gap P1 and a third gap P3, are provided on both sides of the thickness direction of the piezoelectric vibrating plate 2. When the piezoelectric vibrating plate 2 is displaced along the thickness direction, the width of either the first gap P1 or the third gap P3 decreases. Therefore, by using gaps with smaller widths, the reduction in air convection suppression function can be avoided.

[0084] In addition to the first gap P1, the first embodiment also employs a second gap P2 and a third gap P3 connected to the first gap P1. These gaps form a U-shaped gap P. By employing a U-shaped gap P, the overall length of the gap P can be further extended, thus further increasing the frictional stress τ generated between the air in the gap P and the wall of the gap P. At the same time, by employing a U-shape, the possibility of air convection present in each of the acoustic spaces 301 and 302 on both sides of the gap P can be further reduced. As a result, by employing the gap P according to the first embodiment, a piezoelectric sound-generating component 1 with good sound pressure characteristics can be obtained.

[0085] Furthermore, in the first embodiment, when the piezoelectric vibrating plate 2 is fixed to the housing 5, only the first peripheral portion 13, i.e., the four corners of the vibrating plate 10, is fixed to the housing 5. On the other hand, the portion of the piezoelectric vibrating plate 2 other than the first peripheral portion 13, i.e., the vibrating portion V, is configured to be movable relative to the housing 5. Therefore, even if the piezoelectric vibrating plate 2 is not provided with slits, the influence on the vibration displacement of the vibrating portion V is small, and it can vibrate at the same large amplitude as the piezoelectric vibrating plate 200 provided with slits 130 in the comparative example. As a result, the structure of the piezoelectric vibrating plate 2 can be simplified, and the sound conversion efficiency of the piezoelectric sound-generating component 1 according to the first embodiment can be maintained.

[0086] As described above, in the first embodiment, by employing a gap P consisting of a stepped portion 34 and a second peripheral portion 12 having the above-described features, it is possible to provide a piezoelectric sound-generating component that can maintain sound conversion efficiency and obtain good sound pressure characteristics using a simple structure.

[0087] [Second Implementation]

[0088] Next, refer to Figure 6 and Figure 7 The structure of the step portion 34B according to the second embodiment will be described. Figure 6 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the second embodiment. Figure 7 This is a cross-sectional view showing the state of each structure of the piezoelectric sound-generating component when the piezoelectric vibrating plate 2 according to the second embodiment vibrates.

[0089] Furthermore, in the following description, the description of aspects common to the first embodiment in the second embodiment is omitted, and the differences, namely the structure of the step portion 34B and the arrangement relationship between the piezoelectric vibrating plate 2 and the step portion 34B, will be explained. In particular, the same effects resulting from the same structure are not mentioned. The same applies to the third to sixth embodiments described later.

[0090] like Figure 6 As shown, unlike the step portion 34 in the first embodiment, the step portion 34B in the second embodiment is only provided on the housing body 3B. Furthermore, the step portion 34B may also be provided only on the cover 4B instead of being provided on the housing body 3B. Additionally, the step portion 34B is provided on the first main surface 111 side of the piezoelectric vibrating plate 2.

[0091] In the second embodiment, when the piezoelectric vibrating plate 2 is not vibrating, such as Figure 6 As shown, the first main surface 111 of the second peripheral portion 12 is configured not to contact the first step surface 343B of the step portion 34B. In this case, a first gap P1B is formed between the first step surface 343B of the step portion 34B and the first main surface 111 of the second peripheral portion 12. Thus, an L-shaped gap PB is formed by the first gap P1B and the second gap P2. In addition, in the thickness direction of the piezoelectric vibrating plate 2, the width dimension H1B of the first gap P1B is 0.35mm or less.

[0092] Furthermore, in the second embodiment, when the piezoelectric vibrating plate 2 is not vibrating, the piezoelectric vibrating plate 2 can also be configured to have the first main surface 111 in contact with the first step surface 343B of the step portion 34B. That is, the width dimension H1B of the first gap P1B can also be 0.00mm. In this case, when the piezoelectric vibrating plate 2 vibrates in the second direction, such as Figure 7 As shown, the first main surface 111 of the piezoelectric vibrating plate 2 separates from the first step surface 343B of the step portion 34B. In this case, the width dimension H1B of the first gap P1B becomes larger. In addition, the maximum value of the width dimension H1B of the first gap P1B is 0.35mm or less.

[0093] Thus, in the second embodiment, by employing the step portion 34B and the second peripheral portion 12 configured as described above, the same effect as in the first embodiment can be achieved, and the structure of the step portion can be simplified. Furthermore, when the piezoelectric vibrating plate 2 is not vibrating, it is configured to contact the step portion 34B, thereby improving the simplicity and stability of installing the piezoelectric vibrating plate 2 onto the housing body 3.

[0094] [Third Implementation Method]

[0095] Next, refer to Figure 8 The structure of the step portion 34C according to the third embodiment will be described. Figure 8 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the third embodiment.

[0096] like Figure 8 As shown, unlike the stepped portion 34 in the first embodiment, the stepped portion 34C in the third embodiment is only provided on the housing body 3C. Furthermore, the stepped portion 34C may also be provided only on the cover 4C instead of being provided on the housing body 3C. Additionally, the stepped portion 34C is provided on the second main surface 112 side of the piezoelectric vibrating plate 2.

[0097] In the third embodiment, when the piezoelectric vibrating plate 2 is not vibrating, such as Figure 8 As shown, the second main surface 112 of the second peripheral portion 12 of the piezoelectric vibrating plate 2 is configured not to contact the second step surface 343C of the step portion 34C. In this case, a second gap P2 is formed between the inner peripheral surface 321 and the side surface 113 of the second peripheral portion 12, and a third gap P3C is formed between the second step surface 343C of the step portion 34C and the second main surface 112 of the second peripheral portion 12. Thus, an L-shaped gap PC is formed by the second gap P2 and the third gap P3C. In addition, in the thickness direction of the piezoelectric vibrating plate 2, the width dimension H1C of the third gap P3C is 0.35 mm or less.

[0098] In the third embodiment, when the piezoelectric vibrating plate 2 is not vibrating, it can also be configured such that its second main surface 112 contacts the second step surface 343C of the step portion 34C. That is, the width dimension H1C of the third gap P3C can also be 0.00 mm. In this case, if the piezoelectric vibrating plate 2 vibrates in the first direction, the second main surface 112 of the piezoelectric vibrating plate 2 moves away from the second step surface 343C of the step portion 34C. In this case, the width dimension H1C of the third gap P3C increases. Furthermore, the maximum value of the width dimension H1C of the third gap P3C is 0.35 mm or less.

[0099] Thus, in the third embodiment, by adopting the step portion 34C and the second peripheral portion 12 configured as described above, the same effect as in the first embodiment can be achieved, and the structure of the step portion can be simplified.

[0100] [Fourth Implementation Method]

[0101] Next, refer to Figure 9 The structure of the step portion 34D according to the fourth embodiment will be described. Figure 9This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the fourth embodiment.

[0102] like Figure 9 As shown, unlike the stepped portion 34 in the first embodiment, the stepped portion 34D in the fourth embodiment is a recess formed in the first peripheral wall portion 32D of the housing body 3D. Furthermore, the stepped portion 34D is only provided on the first main surface 111 side of the piezoelectric vibrating plate 2. In this case, a first gap P1 is formed between the first stepped surface 343D of the stepped portion 34D and the first main surface 111 of the second peripheral portion 12, and a second gap P2 is formed between the inner peripheral surface 321 and the side surface 113 of the second peripheral portion 12. Thus, an L-shaped gap PD is formed by the first gap P1 and the second gap P2. Additionally, in the thickness direction of the piezoelectric vibrating plate 2, the width dimension H1D of the first gap P1 is 0.35 mm or less.

[0103] Thus, in the fourth embodiment, by employing the stepped portion 34D and the second peripheral portion 12 configured as described above, the same effect as in the first embodiment can be achieved, and the stepped portion 34D can be formed using the first peripheral wall portion 32D of the shell body 3D. As a result, the structure of the stepped portion 34D and the shell body 3D can be simplified, and the shell strength can also be improved.

[0104] [Fifth Implementation Method]

[0105] Next, refer to Figure 10 The structure of the step portion 34E according to the fifth embodiment will be described. Figure 10 This is a cross-sectional view showing the structure of the piezoelectric sound-generating component according to the fifth embodiment.

[0106] like Figure 10 As shown, unlike the stepped portion 34 in the first embodiment, the stepped portion 34E in the fifth embodiment is a recess formed in the first peripheral wall portion 32E of the housing body 3E. Furthermore, the stepped portion 34E is provided on both sides of the piezoelectric vibrating plate 2 in the thickness direction. Specifically, the stepped portion 34E has a first stepped portion 341E provided in the housing body 3E and a second stepped portion 342E provided in the cover 4. Additionally, a first gap P1 is formed between the first stepped surface 343E of the first stepped portion 341E and the first main surface 111 of the second peripheral portion 12, a second gap P2 is formed between the inner peripheral surface 321E and the side surface 113 of the second peripheral portion 12, and a third gap P3 is formed between the second stepped surface 344E of the second stepped portion 342E and the second main surface 112 of the second peripheral portion 12. The dimensions of the first gap P1, the second gap P2, and the third gap P3 involved in the fifth embodiment, as well as the U-shaped gap P formed by these gaps, are the same as those of the U-shaped gap P involved in the first embodiment.

[0107] Thus, in the fifth embodiment, by employing the stepped portion 34E and the second peripheral portion 12 configured as described above, the same effect as in the first embodiment can be achieved, and the stepped portion 34E can be formed using the first peripheral wall portion 32E of the shell body 3E. As a result, the structure of the shell body 3E can be simplified, and the shell strength can also be improved.

[0108] [Sixth Implementation Method]

[0109] Next, refer to Figure 11 The structure of the piezoelectric sound-generating component 1F according to the sixth embodiment will be described. Figure 11 This is an exploded perspective view showing the structure of the piezoelectric sound-generating component 1F according to the sixth embodiment.

[0110] like Figure 11 As shown, unlike the top view shapes of the housing body 3, cover 4, vibrating plate 10, first step portion 341 provided on the housing body 3, and second step portion 342 provided on the cover 4 in the first embodiment, the top view shapes of the main surfaces of the housing body 3F, cover 4F, and vibrating plate 10F in the sixth embodiment are all circular, and the top view shapes of the first step portion 341F provided on the housing body 3F and the second step portion 342F provided on the cover 4F are both annular. On the other hand, features other than the top view shape of the structure in the sixth embodiment are the same as those in the first embodiment. Furthermore, the other structures of the piezoelectric sound-generating component 1F in the sixth embodiment are the same as those in the piezoelectric sound-generating component 1 in the first embodiment.

[0111] The vibrating plate 10F according to the sixth embodiment has a second peripheral portion 12F and four first peripheral portions 13F formed on the circumference of the second peripheral portion 12F. Additionally, four pressing portions 345F are formed at positions corresponding to the four first peripheral portions 13F on the first stepped portion 341F. Four pressing portions 346F are formed at positions corresponding to the four first peripheral portions 13F on the second stepped portion 342F. In the assembled state, the first peripheral portions 13F are clamped and fixed to the housing by the pressing portions 345F and 346F, and the second peripheral portion 12F is movable relative to the housing. Furthermore, the number of first peripheral portions 13F and the number of pressing portions 345F and 346F used to fix the first peripheral portions 13F can be more than four or less than four.

[0112] Thus, in the sixth embodiment, by employing the piezoelectric sound-generating component 1F described above, the same effect as in the first embodiment can be achieved, and the design freedom of the piezoelectric sound-generating component 1F can be increased.

[0113] The exemplary embodiments of the present invention have been described above.

[0114] In one embodiment of the present invention, a piezoelectric sound-generating component 1 includes: a piezoelectric vibrating plate 2 having a vibrating plate 10 and a piezoelectric body 20, the vibrating plate 10 having a central portion 11 and a peripheral portion 15 located around the central portion 11, the piezoelectric body 20 being disposed in the central portion 11; and a housing 5 having an internal space 30, and housing the piezoelectric vibrating plate 2 within the internal space 30, the peripheral portion 15 of the vibrating plate 10 having a first peripheral portion 13 fixed to the housing 5 and a second peripheral portion 12 movable relative to the housing 5, the housing 5 having a stepped portion 34 disposed in the thickness direction of the vibrating plate 10 at a position corresponding to the second peripheral portion 12, and a gap P being formed between the stepped portion 34 and the second peripheral portion 12.

[0115] Based on the above structure, a piezoelectric sound-generating component can be provided, which can maintain sound conversion efficiency and obtain good sound pressure characteristics using a simple structure.

[0116] Alternatively, in the above structure, the stepped portion 34 may be a protrusion or a recess formed on the peripheral wall of the housing 5.

[0117] Based on the above structure, a step section with a simple structure can be constructed.

[0118] Alternatively, in the above structure, the housing 5 may have a housing body 3 with an opening 323 and a cover 4 that closes the opening 323 of the housing body 3. The housing body 3 has a first top wall portion 31 opposite to the first main surface 111 of the vibrating plate 10 and a first peripheral wall portion 32 disposed at the end of the first top wall portion 31. The cover 4 has a second top wall portion 41 opposite to the second main surface 112 of the vibrating plate 10 and a second peripheral wall portion 42 disposed at the end of the second top wall portion 41. The step portion 34 has a first step portion 341 formed in the thickness direction on the side of the first main surface 111 of the second peripheral portion 12. The first step portion 341 is disposed on either the first peripheral wall portion 32 or the second peripheral wall portion 42. The gap P includes a first gap P1 formed in the thickness direction between the opposing surfaces of the second peripheral portion 12 and the first step portion 341.

[0119] According to the above structure, by forming a first gap along the main surface direction of the vibrating plate, it is possible to suppress the convection of air on both sides of the thickness direction of the vibrating plate through the first gap.

[0120] Alternatively, in the above structure, the surfaces of the first step portion 341 and the second peripheral portion 12 facing each other in the thickness direction may be the first main surface 111 of the vibrating plate 10 and the opposing surface of the first step portion 341 facing the first main surface 111, i.e., the first step surface 343. The first gap P1 is the gap surrounded by the first main surface 111 and the first step surface 343 of the first step portion 341 when the first main surface 111 of the vibrating plate 10 and the first step surface 343 of the first step portion 341 are not in contact. Or, it is the gap generated between the first main surface 111 and the first step surface 343 of the first step portion 341 of the vibrating plate 10 due to the vibration of the piezoelectric vibrating plate 2 when the first main surface 111 of the vibrating plate 10 and the first step surface 343 of the first step portion 341 are in contact.

[0121] According to the above structure, a first gap can be formed before and during the vibration of the diaphragm, which can improve the degree of freedom of the first gap and suppress the change in sound pressure characteristics caused by air convection.

[0122] Alternatively, in the above structure, the width dimension H1 in the thickness direction of the first gap P1 can be the distance between the first main surface 111 of the vibrating plate 10 and the first step surface 343 of the first step portion 341, and the width dimension H1 of the first gap P1 can be 0.35mm or less.

[0123] According to the above structure, by making the width of the first gap along the main surface direction of the vibrating plate smaller, the convection of air on both sides of the thickness direction of the vibrating plate through the first gap can be reliably suppressed, thereby improving the sound pressure characteristics.

[0124] Alternatively, in the above structure, the length dimension L1 of the first gap P1 in the main surface direction of the vibrating plate 10 may be the same as the length of the first step portion 341 in the main surface direction. In the first gap P1, the length dimension L1 is formed to be larger than the width dimension H1.

[0125] Based on the above structure, by ensuring the length of the first gap sufficiently, the effect of the first gap in suppressing air convection can be improved.

[0126] Alternatively, in the above structure, the gap P may include a second gap P2, which is formed between the surfaces of either the first peripheral wall portion 32 or the second peripheral wall portion 42, where the first step portion 341 is provided, and the surfaces of the second peripheral edge portion 12 that are opposite to each other.

[0127] According to the above structure, by forming a second gap along a direction intersecting the main surface direction of the vibrating plate, the length of the gap can be extended, thus reliably achieving the effect of the gap suppressing air convection.

[0128] Alternatively, in the above structure, the second gap P2 may be a gap surrounded by the side surface 113 of the second peripheral portion 12 and the inner peripheral surface of either the first peripheral wall portion 32 or the second peripheral wall portion 42, which is provided with the first step portion 341, and is intersecting and connected with the first gap P1.

[0129] Based on the above structure, an L-shaped gap can be formed, which can improve the effect of suppressing air convection based on the gap.

[0130] Alternatively, in the above structure, the step portion 34 may also have a second step portion 342 formed in the thickness direction on the second main surface 112 side of the second peripheral portion 12. The second step portion 342 is provided in the first peripheral wall portion 32 and the second peripheral wall portion 42 in a manner opposite to the first step portion 341, and the gap P includes a third gap P3 formed in the thickness direction between the opposing surfaces of the second step portion 342 and the second peripheral portion 12.

[0131] Based on the above structure, a third gap can be formed along the main surface direction of the vibrating plate, which can further extend the length of the gap and improve the effect of the gap in suppressing air convection.

[0132] Alternatively, in the above structure, the surfaces of the second step portion 342 and the second peripheral portion 12 facing each other in the thickness direction are the second main surface 112 of the vibrating plate 10 and the opposing surface of the second step portion 342 facing the second main surface 112, namely the second step surface 344. The third gap P3 is a gap surrounded by the second main surface 112 of the vibrating plate 10 and the second step surface 344 of the second step portion 342, and is intersecting and connected with the second gap P2.

[0133] Based on the above structure, a U-shaped gap can be formed, which can improve the effect of suppressing air convection based on the gap and obtain good sound pressure characteristics.

[0134] Alternatively, in the above structure, the width dimension H3 in the thickness direction of the third gap P3 may be the distance between the second main surface 112 of the vibrating plate 10 and the second step surface 344 of the second step portion 342, and the width dimension H3 of the third gap P3 may be larger than the width dimension H1 of the first gap P1.

[0135] According to the above structure, the width of the first gap can be made smaller, and the width of the third gap in the thickness direction can be made larger than the width of the first gap. This ensures the effect of suppressing air convection based on the gap, and the processing of the step portion and the placement of the vibrating plate on the step portion can be easily performed.

[0136] Alternatively, in the above structure, the top view shape of the main surface of the vibrating plate 10 can be circular or rectangular.

[0137] Based on the above structure, the design freedom of the vibrating plate can be improved.

[0138] Alternatively, in the above structure, the first peripheral portion 13 may be fixed to the housing 5 in two or more places.

[0139] Based on the above structure, the installation stability of the vibrating plate to the shell is improved, thereby improving the stability of the sound pressure characteristics.

[0140] Alternatively, in the above structure, when the top view of the main surface of the vibrating plate 10 is rectangular, the first peripheral portion 13 is the four corners of the vibrating plate 10.

[0141] Based on the above structure, the stability of the diaphragm installation can be improved, and the influence of the fixed part on the vibrating part can be reduced, thereby maintaining the sound conversion efficiency.

[0142] Furthermore, the embodiments described above are for ease of understanding of the present invention and are not intended to limit or interpret the present invention. The present invention can be modified / improved without departing from its spirit, and the present invention also includes its equivalents. That is, those skilled in the art can make appropriate design changes to the embodiments, as long as they possess the features of the present invention, and these are included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, dimensions, etc., of each embodiment are not limited to the examples and can be appropriately modified. In addition, the embodiments are examples, and of course, partial substitutions or combinations of the structures shown in different embodiments are possible; these, as long as they contain the features of the present invention, are also included within the scope of the present invention.

[0143] Explanation of reference numerals in the attached figures

[0144] 1…Piezoelectric sound-generating component; 2…Piezoelectric vibrating plate; 3…Main body of the housing; 4…Cover; 5…Housing; 10…Vibrating plate; 11…Central part; 12…Second peripheral part; 13…First peripheral part; 15…Peripheral part; 20…Piezoelectric body; 30…Internal space; 31…First top wall part; 32…First peripheral wall part; 34…Step part; P…Gap; 50…Pin terminal.

Claims

1. A piezoelectric sound generating component, wherein, Possessing: a piezoelectric vibrating plate having a vibrating plate and a piezoelectric body, the vibrating plate having a central portion and a peripheral portion located around the central portion, the piezoelectric body being provided to the central portion; and a case having an internal space and housing the piezoelectric vibrating plate in the internal space, the peripheral portion of the vibrating plate has a first peripheral portion fixed to the case and a second peripheral portion movable with respect to the case, the case has a stepped portion provided to a position corresponding to the second peripheral portion in a thickness direction of the vibrating plate, a gap is formed between the stepped portion and the second peripheral portion.

2. The piezoelectric sound production member according to claim 1, wherein the stepped portion is a convex portion or a concave portion formed in the case.

3. The piezoelectric sound production member according to claim 1 or 2, wherein the case has a case main body with an opening and a lid closing the opening of the case main body, the case main body has a first top wall portion facing a main surface of one side of the vibrating plate and a first peripheral wall portion provided to an end portion of the first top wall portion, the lid has a second top wall portion facing a main surface of the other side of the vibrating plate and a second peripheral wall portion provided to an end portion of the second top wall portion, the stepped portion has a first stepped portion formed on one side of the second peripheral portion in the thickness direction, the first stepped portion is provided to either one of the first peripheral wall portion and the second peripheral wall portion, the gap includes a first gap formed between the second peripheral portion and the first stepped portion in the thickness direction.

4. The piezoelectric sound production member according to claim 3, wherein the opposing surfaces of the first stepped portion and the second peripheral portion to each other in the thickness direction are one main surface of the vibrating plate and an opposing surface of the first stepped portion on a side facing the one main surface, the first gap is a gap surrounded by the one main surface of the vibrating plate and the opposing surface of the first stepped portion when the one main surface of the vibrating plate and the opposing surface of the first stepped portion are not in contact, or a gap generated between the one main surface of the vibrating plate and the opposing surface of the first stepped portion due to vibration of the piezoelectric vibrating plate when the one main surface of the vibrating plate and the opposing surface of the first stepped portion are in contact.

5. The piezoelectric sound production member according to claim 4, wherein a width dimension of the first gap in the thickness direction is a distance between the one main surface of the vibrating plate and the opposing surface of the first stepped portion, the width dimension of the first gap is 0.35 mm or less.

6. The piezoelectric sound production member according to claim 5, wherein a length dimension of the first gap in a direction of a main surface of the vibrating plate is a length of the first stepped portion in the direction of the main surface, the length dimension is larger than the width dimension in the first gap.

7. The piezoelectric sound production member according to claim 3, wherein ​ The void includes a second void formed in the thickness direction of the vibration plate between the second peripheral edge portion and either one of the first peripheral wall portion and the second peripheral wall portion provided with the first step portion.

8. The piezoelectric sound generating component according to claim 7, wherein The second void is a void surrounded by a side surface of the second peripheral edge portion and an inner peripheral surface of either one of the first peripheral wall portion and the second peripheral wall portion provided with the first step portion, and communicates in a manner crossing the first void.

9. The piezoelectric sound generating component according to claim 3, wherein The step portion further has a second step portion formed in the thickness direction on the other side of the second peripheral edge portion, The second step portion is provided in the one of the first peripheral wall portion and the second peripheral wall portion which is not provided with the first step portion, in a manner opposite to the first step portion, The void includes a third void formed in the thickness direction between the second step portion and the opposite surface of the second peripheral edge portion.

10. The piezoelectric sound generating component according to claim 9, wherein The opposite surface of the second step portion and the second peripheral edge portion in the thickness direction is the other main surface of the vibration plate, and an opposite surface of the second step portion on the side toward the other main surface, The third void is a void surrounded by the other main surface of the vibration plate and the opposite surface of the second step portion, and communicates in a manner crossing the second void surrounded by a side surface of the second peripheral edge portion and an inner peripheral surface of either one of the first peripheral wall portion and the second peripheral wall portion provided with the second step portion.

11. The piezoelectric sound generating component according to claim 10, wherein The width dimension of the third void in the thickness direction is a distance between the other main surface of the vibration plate and the opposite surface of the second step portion, The width dimension of the third void can be formed larger than the width dimension of the first void.

12. The piezoelectric sound generating component according to claim 1 or 2, wherein The plan view shape of the main surface of the vibration plate is a circular shape or a rectangular shape.

13. The piezoelectric sound generating component according to claim 1 or 2, wherein The first peripheral edge portion is fixed to the housing at two or more places.

14. The piezoelectric sound generating component according to claim 13, wherein When the plan view shape of the main surface of the vibration plate is a rectangular shape, the first peripheral edge portion is four corner portions of the vibration plate.

Images