Ultrasonic transducer and parametric speaker provided with same

Abstract

The first vibrating plate (110) resonates and vibrates in a direction orthogonal to the first vibrating plate (110) at a phase opposite to the phase of the at least one single-chip piezoelectric vibrator (130). The dimension (L1) of the inner side of the at least one frame body (120) in the longitudinal direction is at least four times the dimension of the inner side of the at least one frame body (120) in the short direction orthogonal to the longitudinal direction. The second diaphragm (135) is positioned in a region sandwiched between both end edges (120s1, 120s2) in the short-side direction of the inner peripheral surface of the at least one housing (120) when viewed from a direction orthogonal to the first diaphragm (110), and the second diaphragm (135) is positioned in the short-side direction in a region sandwiched between both end edges (120s1, 120s2) in the short-side direction of the inner peripheral surface of the at least one housing (120). The average distance (D1) in the short-side direction between one end edge (120s1) in the short-side direction of the inner peripheral surface of the at least one frame (120) and one end edge (135s1) in the short-side direction of the second diaphragm (135), and the average distance (D2) in the short-side direction between the other end edge (120s2) in the short-side direction of the inner peripheral surface of the at least one frame (120) and the other end edge (135s2) in the short-side direction of the second diaphragm (135) are respectively equal to (D1, D2) in the short-side direction. The dimension (L2) of the inner side of at least one frame body (120) in the short side direction is 1 / 6 or less.

Description

Technical Field

[0001] The present invention relates to an ultrasonic transducer and a parametric loudspeaker including the ultrasonic transducer. Background Art

[0002] As prior art documents disclosing the structure of a superdirective sound device, there are Japanese Patent Application Laid-Open No. 2003-47085 (Patent Document 1) and Japanese Patent No. 6333480 (Patent Document 2). The superdirective sound device described in Patent Document 1 is configured such that a plurality of ultrasonic transducers are arranged on a single printed circuit board and are arranged such that their outer peripheries form a substantially circular shape. The plurality of ultrasonic transducers are divided into two groups having different mounting heights.

[0003] The superdirective sound device described in Patent Document 2 includes a first ultrasonic emitter and a second ultrasonic emitter. The second ultrasonic emitter is arranged on the axis of the first ultrasonic emitter and in front of the radiation surface. The phase of the carrier signal radiated by the second ultrasonic emitter is opposite to the phase of the carrier signal included in the signal radiated by the first ultrasonic emitter.

[0004] Prior art documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-47085

[0007] Patent Document 2: Japanese Patent No. 6333480 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the superdirective sound device described in Patent Document 1, a plurality of ultrasonic transducers are arranged in two groups having different mounting heights, and the structure is relatively complex. In the superdirective sound device described in Patent Document 2, the second ultrasonic emitter is arranged outside the first ultrasonic emitter, and the device becomes large-sized.

[0010] The present invention has been made in view of the above problems, and an object thereof is to provide an ultrasonic transducer and a parametric loudspeaker including the ultrasonic transducer, which can improve the sound pressure level with a simple and miniaturized structure.

[0011] Means for Solving the Problems

[0012] The ultrasonic transducer based on the present invention includes a first diaphragm, at least one frame, and at least one single-chip piezoelectric vibrator. At least one frame extends in the longitudinal direction and is joined to the first diaphragm. At least one single-chip piezoelectric vibrator is respectively mounted on at least one frame. At least one single-chip piezoelectric vibrator includes a piezoelectric body facing the first diaphragm at a distance and a second diaphragm provided on the side of the piezoelectric body opposite to the side where the frame is located. The first diaphragm resonates and vibrates in a direction orthogonal to the first diaphragm with a phase opposite to that of at least one single-chip piezoelectric vibrator. The dimension of the inner side of at least one frame in the longitudinal direction is more than 4 times the dimension of the inner side of at least one frame in the short side direction orthogonal to the longitudinal direction. When viewed from the direction orthogonal to the first diaphragm, the second diaphragm is located in the region sandwiched by the two end edges of the inner peripheral surface of at least one frame in the short side direction in the short side direction. In the second diaphragm, the average distance in the short side direction between one end edge of the inner peripheral surface of at least one frame in the short side direction and one end edge of the second diaphragm in the short side direction, and the average distance in the short side direction between the other end edge of the inner peripheral surface of at least one frame in the short side direction and the other end edge of the second diaphragm in the short side direction are respectively 1 / 6 or less of the dimension of the inner side of at least one frame in the short side direction.

[0013] Effect of the Invention

[0014] According to the present invention, it is possible to improve the sound pressure level with a simple and miniaturized structure in an ultrasonic transducer. Description of the Drawings

[0015] Figure 1 It is a longitudinal sectional view showing the structure of the ultrasonic transducer according to Embodiment 1 of the present invention.

[0016] Figure 2 It is an exploded perspective view showing the structure of the ultrasonic transducer according to Embodiment 1 of the present invention.

[0017] Figure 3 It is a perspective view showing the structure of the frame included in the ultrasonic transducer according to Embodiment 1 of the present invention.

[0018] Figure 4 It is viewed from the direction of arrow IV Figure 2 of the ultrasonic transducer.

[0019] Figure 5 It is a sectional view showing the structure of the single-chip piezoelectric vibrator included in the ultrasonic transducer according to Embodiment 1 of the present invention.

[0020] Figure 6It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to Embodiment 1 of the present invention transmits or receives ultrasonic waves.

[0021] Figure 7 It is a cross-sectional view of the ultrasonic transducer viewed from the direction of the arrow along line VII-VII. Figure 6 of the ultrasonic transducer.

[0022] Figure 8 It is a graph showing the change in the resonance frequency of the first vibration plate when the short side dimension inside the housing is fixed and the long side dimension is changed, obtained by performing simulation analysis using the finite element method.

[0023] Figure 9 It is a graph showing the change in the sound pressure of the ultrasonic waves transmitted from the ultrasonic transducer when the short side dimension inside the housing is fixed and the long side dimension is changed, obtained by performing simulation analysis using the finite element method.

[0024] Figure 10 It is a graph showing the change in the sound pressure of the ultrasonic waves transmitted from the ultrasonic transducer when the minimum dimension in the second direction (Y-axis direction) of the ultrasonic oscillator is changed, obtained by performing simulation analysis using the finite element method.

[0025] Figure 11 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to the first embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 24 mm, transmits or receives ultrasonic waves.

[0026] Figure 12 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to the second embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 16 mm, transmits or receives ultrasonic waves.

[0027] Figure 13 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to the third embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 15 mm, transmits or receives ultrasonic waves.

[0028] Figure 14 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to the fourth example, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 14.5 mm, transmits or receives ultrasonic waves.

[0029] Figure 15 It is a cross-sectional view of the ultrasonic transducer viewed from the direction of the arrow along line XV-XV. Figure 14 of the ultrasonic transducer.

[0030] Figure 16 FIG. 5 is a view of the ultrasonic transducer according to the fifth embodiment of Embodiment 1 of the present invention as viewed from the ultrasonic oscillator side.

[0031] Figure 17 FIG. 6 is a view of the ultrasonic transducer according to the sixth embodiment of Embodiment 1 of the present invention as viewed from the ultrasonic oscillator side.

[0032] Figure 18 FIG. 7 is a cross-sectional view showing the structure of the ultrasonic transducer according to the seventh embodiment of Embodiment 1 of the present invention.

[0033] Figure 19 FIG. 8 is a graph obtained by performing a simulation analysis using the finite element method of the transition of the displacement of the first diaphragm when the center position in the first direction (X-axis direction) of the second diaphragm is fixed and the short side dimension W of the second diaphragm is changed in the first experimental example.

[0034] Figure 20 FIG. 9 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the first comparative example transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second diaphragm is 1 mm, and the average distances D1 and D2 are 0.4 mm respectively.

[0035] Figure 21 FIG. 10 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the eighth embodiment transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second diaphragm is 1.5 mm, and the average distances D1 and D2 are 0.15 mm respectively.

[0036] Figure 22 FIG. 11 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the second comparative example transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second diaphragm is 2 mm, and the average distances D1 and D2 are -0.1 mm respectively.

[0037] Figure 23 FIG. 12 is a graph obtained by performing a simulation analysis using the finite element method of the transition of the displacement of the first diaphragm when the thickness of the piezoelectric body is changed to 0.2 mm with respect to the analysis conditions of the first experimental example, the center position in the first direction (X-axis direction) of the second diaphragm is fixed, and the short side dimension W of the second diaphragm is changed in the second experimental example.

[0038] Figure 24It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when, in the third experimental example, the thickness of the second vibrating plate is changed to 0.3 mm relative to the analysis conditions of the first experimental example, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0039] Figure 25 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when, in the fourth experimental example, the short side dimension inside the frame is changed to 2.2 mm relative to the analysis conditions of the first experimental example, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0040] Figure 26 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when, in the fifth experimental example, the thickness of the piezoelectric body is changed to 0.2 mm, the short side dimension inside the frame is changed to 2.2 mm relative to the analysis conditions of the first experimental example, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0041] Figure 27 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when, in the sixth experimental example, the material of the second vibrating plate is changed to piezoelectric ceramics, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0042] Figure 28 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when, in the seventh experimental example, the center position of the second vibrating plate in the first direction (X-axis direction) is offset.

[0043] Figure 29 It is a cross-sectional view showing the displacement state obtained by using the finite element method for simulation analysis when the ultrasonic transducer of the ninth embodiment transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.5 mm, the offset amount of the center position of the second vibrating plate in the first direction (X-axis direction) is 0.15 mm, the average distance D1 is 0 mm, and the average distance D2 is 0.3 mm in the seventh experimental example.

[0044] Figure 30It is a cross-sectional view showing the displacement state obtained by simulation analysis using the finite element method when the ultrasonic transducer of the third comparison example sends or receives ultrasonic waves, in which the short side dimension W of the second vibration plate in the first direction (X-axis direction) is 1.2 mm, the offset of the center position of the second vibration plate in the first direction (X-axis direction) is 0.3 mm, the average distance D1 is 0 mm, and the average distance D2 is 0.6 mm in the seventh experimental example.

[0045] Figure 31 This is a perspective view of the ultrasonic transducer according to the first modified example of the first embodiment of the present invention as viewed from the second vibration plate side.

[0046] Figure 32 This is a perspective view of an ultrasonic transducer according to a second modified example of the first embodiment of the present invention as viewed from the first diaphragm side.

[0047] Figure 33 This is a side view showing the structure of an ultrasonic transducer according to Embodiment 2 of the present invention.

[0048] Figure 34 Observed from the direction of arrow XXXIV Figure 33 Rear view of the ultrasonic transducer shown.

[0049] Figure 35 It is an exploded perspective view showing a stacked state of various components of an ultrasonic transducer according to a second embodiment of the present invention.

[0050] Figure 36 It is a plan view showing the positional relationship in the first direction (X-axis direction) in the step of cutting the piezoelectric body of the ultrasonic transducer according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0051] The ultrasonic transducers according to various embodiments of the present invention are described below with reference to the accompanying drawings. In the following descriptions of the embodiments, identical or equivalent parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. The present invention is applicable to applications requiring high sound pressure ultrasonic waves, such as ultrasonic transducers for parametric loudspeakers, ultrasonic sensors, and non-contact tactile sensing. While the following embodiments illustrate ultrasonic transducers for parametric loudspeakers, the applications of ultrasonic transducers are not limited thereto.

[0052] (Implementation 1)

[0053] Figure 1 It is a longitudinal sectional view showing the structure of the ultrasonic transducer according to the first embodiment of the present invention. Figure 2 : is an exploded perspective view showing the structure of the ultrasonic transducer according to the first embodiment of the present invention. Figure 1 and Figure 2As shown, the ultrasonic transducer 100 of Embodiment 1 of the present invention includes a first diaphragm 110, a housing 120, and a single-chip piezoelectric vibrator 130.

[0054] The first diaphragm 110 has a flat plate shape. The first diaphragm 110 is formed of an aluminum alloy such as duralumin containing aluminum, or a metal such as stainless steel. In the present embodiment, the first diaphragm 110 is formed of an aluminum alloy. Since the Young's modulus of the aluminum alloy is small, by forming the first diaphragm 110 of the aluminum alloy, the stress generated in the first diaphragm 110 during the driving of the ultrasonic transducer 100 can be reduced. The thickness of the first diaphragm 110 is, for example, 0.05 mm or more and 0.2 mm or less.

[0055] The housing 120 has a rectangular ring shape. The housing 120 has a short side direction along the first direction (X-axis direction) and a long side direction along the second direction (Y-axis direction). The housing 120 extends in the second direction (Y-axis direction). The axial direction of the housing 120 is along the third direction (Z-axis direction). One end of the housing 120 in the third direction (Z-axis direction) is joined to the first diaphragm 110 by an adhesive composed of epoxy resin or the like.

[0056] The housing 120 is formed of a metal such as an aluminum alloy, a nickel-iron alloy (42Ni-Fe), or stainless steel, a glass epoxy material, or a resin. From the viewpoint of suppressing characteristic changes of the ultrasonic transducer 100 due to temperature changes, the housing 120 is preferably formed of a metal. On the other hand, from the viewpoints of making the ultrasonic waves transmitted or received by the ultrasonic transducer 100 have a lower frequency and making the ultrasonic transducer 100 smaller, the housing 120 is preferably formed of a resin. In the present embodiment, the housing 120 is formed of stainless steel. The thickness of the housing 120 is, for example, 0.2 mm or more and 0.6 mm or less.

[0057] Figure 3 is a perspective view showing the structure of the housing included in the ultrasonic transducer of Embodiment 1 of the present invention. As Figure 3 shown, the housing 120 has a pair of long side portions 121 extending in the second direction (Y-axis direction) and a pair of short side portions 122 extending in the first direction (X-axis direction). The pair of long side portions 121 and the pair of short side portions 122 are continuous to form the inner peripheral surface of the housing 120. The average interval between the short side portions 122 is 4 times or more the shortest interval between the long side portions 121. That is, the long side dimension L1 in the second direction (Y-axis direction) on the inner side of the housing 120 is 4 times or more the short side dimension L2 in the first direction (X-axis direction) on the inner side of the housing 120.

[0058] Furthermore, the corners between the long side 121 and the short side 122 may be chamfered. Furthermore, the short side 122 is not limited to being linear when viewed from the third direction (Z-axis direction), but may also be an arcuate shape convex toward the inside of the frame 120 or an arcuate shape convex toward the outside of the frame 120.

[0059] The resonant frequency of the first diaphragm 110 can be adjusted by changing the short side dimension L2 in the first direction (X-axis direction) inside the frame 120. For example, when the resonant frequency of the first diaphragm 110 is set to 100 kHz or higher, the short side dimension L2 is set to 1.5 mm to 3 mm.

[0060] The long side dimension L1 in the second direction (Y-axis direction) inside the frame 120 is at least four times the short side dimension L2. From the perspective of increasing the sound pressure level of the ultrasonic wave transmitted by the ultrasonic transducer 100, the long side dimension L1 is, for example, at least 20 mm.

[0061] Figure 4 Observed from the direction of arrow IV Figure 2 Figure 1 shows the ultrasonic transducer. Figure 1 and Figure 4 As shown, a unimorph piezoelectric vibrator 130 is mounted on the frame 120. Unimorph piezoelectric vibrator 130 includes a piezoelectric body 131 spaced apart from and facing the first vibrating plate 110, and a second vibrating plate 135 disposed on the side of piezoelectric body 131 opposite the frame 120. Piezoelectric body 131 has a rectangular parallelepiped shape. The thickness of piezoelectric body 131 is, for example, 0.1 mm to 0.2 mm. Piezoelectric body 131 is, for example, a piezoelectric ceramic.

[0062] The second vibration plate 135 is formed of a metal such as an aluminum alloy, an iron-nickel alloy (42Ni-Fe) or stainless steel, a glass epoxy material or ceramics. In the present embodiment, the second vibration plate 135 is formed of an iron-nickel alloy (42Ni-Fe). The second vibration plate 135 has a rectangular parallelepiped shape. The second vibration plate 135 is bonded to the piezoelectric body 131. The length of the second vibration plate 135 in the second direction (Y-axis direction) is equal to the length of the piezoelectric body 131 in the second direction (Y-axis direction). The short side dimension W of the second vibration plate 135 in the first direction (X-axis direction) and the short side dimension L2 in the first direction (X-axis direction) of the inner side of the frame 120 satisfy the relationship of (2 / 3) L2≤W<L2. The thickness of the second vibration plate 135 is, for example, greater than 0.2 mm and less than 0.4 mm. In addition, when the shape of the second vibration plate 135 is not a rectangle but an ellipse when viewed from the third direction (Z-axis direction), the short side dimension W is set to an average value.

[0063] like Figure 4As shown, when the second diaphragm 135 is viewed in the third direction (Z-axis direction) orthogonal to the first diaphragm 110, it is located in a region sandwiched by the two end edges 120s1 and 120s2 in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 in the first direction (X-axis direction).

[0064] As Figure 1 shown, in the second diaphragm 135, the average distance D1 in the first direction (X-axis direction) between one end edge 120s1 in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 and one end edge 135s1 in the first direction (X-axis direction) of the second diaphragm 135, and the average distance D2 in the first direction (X-axis direction) between the other end edge 120s2 in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 and the other end edge 135s2 in the first direction (X-axis direction) of the second diaphragm 135 are each 1 / 6 or less of the short side dimension L2 in the first direction (X-axis direction) inside the housing 120.

[0065] As Figure 4 shown, the long side dimension L1 in the second direction (Y-axis direction) inside the housing 120 is larger than the minimum dimension Lm in the second direction (Y-axis direction) of the piezoelectric body 131 in the single wafer type piezoelectric oscillator 130. Here, when the single wafer type piezoelectric oscillator 130 has a stacked structure formed by laminating a plurality of piezoelectric bodies, the minimum dimension Lm in the second direction (Y-axis direction) of the piezoelectric body 131 in the single wafer type piezoelectric oscillator 130 is the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body having the shortest length in the second direction (Y-axis direction) among the plurality of piezoelectric bodies. For example, when the single wafer type piezoelectric oscillator 130 has a stacked structure formed by laminating two piezoelectric bodies 131, the polarization directions Dp of the two piezoelectric bodies 131 face each other in the third direction (Z-axis direction). The electric fields applied to the two piezoelectric bodies 131 also have opposite orientations in the third direction (Z-axis direction), thereby forming a single wafer type piezoelectric oscillator in which the two piezoelectric bodies 131 perform bending vibration in the same manner.

[0066] In Figure 4 it, a state is shown in which the piezoelectric body 131 and the second diaphragm 135 overlap without being offset in the second direction (Y-axis direction). In addition, in the present embodiment, the length of the piezoelectric body 131 in the second direction (Y-axis direction) is shorter than the long side dimension L1 in the second direction (Y-axis direction) inside the housing 120, but it is not limited thereto, and it may also be equal to or greater than the long side dimension L1 in the second direction (Y-axis direction) inside the housing 120.

[0067] At least one end edge 120e in the second direction (Y-axis direction) of the inner peripheral surface of the housing 120, and Figure 2The average distance L3 in the second direction (Y-axis direction) between at least one end edge 130e in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric oscillator 130 shown on the side of the frame body 120 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the frame body 120.

[0068] In the present embodiment, the average distance L3 in the second direction (Y-axis direction) between the end edge 120e on one side in the second direction (Y-axis direction) of the inner peripheral surface of the frame body 120 and the end edge 130e on one side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric oscillator 130 on the side of the frame body 120 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the frame body 120, and the average distance L3 in the second direction (Y-axis direction) between the end edge 120e on the other side in the second direction (Y-axis direction) of the inner peripheral surface of the frame body 120 and the end edge 130e on the other side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric oscillator 130 on the side of the frame body 120 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the frame body 120.

[0069] Figure 5 It is a cross-sectional view showing the structure of the single-chip piezoelectric oscillator included in the ultrasonic transducer according to Embodiment 1 of the present invention. As Figure 1 shown, the single-chip piezoelectric oscillator 130 is mounted on the frame body 120 and faces the first vibration plate 110 with a gap therebetween. Specifically, the single-chip piezoelectric oscillator 130 is mounted on the other ends in the third direction (Z-axis direction) of the pair of long side portions 121 of the frame body 120 and faces the first vibration plate 110 with the inner space of the frame body 120 interposed therebetween.

[0070] As Figure 1 、 Figure 2 and Figure 5 shown, the single-chip piezoelectric oscillator 130 is a piezoelectric element including a piezoelectric body 131. As Figure 5 shown, in the present embodiment, the piezoelectric body 131 is sandwiched between a first electrode 132 and a second electrode 133. The polarization direction Dp of the piezoelectric body 131 is along the third direction (Z-axis direction). The first electrode 132 and the second electrode 133 are electrically connected to a processing circuit 140 to which an AC voltage can be applied.

[0071] Figure 6 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer according to Embodiment 1 of the present invention transmits or receives ultrasonic waves. Figure 7 It is viewed from the arrow direction of line VII-VII Figure 6Cross-sectional view of the ultrasonic transducer. As simulation analysis conditions, the thickness of the first vibration plate 110 is set to 0.1 mm, the thickness of the piezoelectric body 131 is set to 0.1 mm, the thickness of the second vibration plate 135 is set to 0.2 mm, the long side dimension L1 of the inner side of the housing 120 is set to 20 mm, the short side dimension L2 is set to 1.8 mm, and the thickness of the housing 120 in the third direction (Z-axis direction) is set to 0.4 mm.

[0072] As Figure 6 and Figure 7 shown, in the vibration mode of the ultrasonic transducer 100 of Embodiment 1 of the present invention, the first vibration plate 110 resonates and vibrates in the third direction (Z-axis direction) orthogonal to the first vibration plate 110 with a phase opposite to that of the single crystal wafer type piezoelectric vibrator 130. That is, as Figure 7 shown, the displacement direction of the resonance vibration Bm of the first vibration plate 110 and the displacement direction of the resonance vibration Bp of the single crystal wafer type piezoelectric vibrator 130 are in opposite directions in the third direction (Z-axis direction). In the present embodiment, the resonance frequencies of the first vibration plate 110 and the single crystal wafer type piezoelectric vibrator 130 are 100 kHz or more.

[0073] In the first vibration plate 110, the middle portion 110c located in the middle of the long side direction of the inner side of the housing 120 becomes the antinode of the resonance vibration, and the end portions 110e located at both ends of the long side direction of the inner side of the housing 120 become the nodes of the resonance vibration. That is, the portion of the first vibration plate 110 located above the inner space of the housing 120 becomes the vibration region of the resonance vibration. The long side dimension of the vibration region of the first vibration plate 110 is the same as the long side dimension L1 of the inner side of the housing 120, and the short side dimension of the vibration region of the first vibration plate 110 is the same as the short side dimension L2 of the inner side of the housing 120.

[0074] Here, the relationship between the resonance frequency of the first vibration plate 110 and the long side dimension L1 of the inner side of the housing 120 will be described.

[0075] Figure 8 is a graph obtained by simulating and analyzing the change in the resonance frequency of the first vibration plate when the short side dimension of the inner side of the housing is fixed and the long side dimension is changed using the finite element method. In Figure 8 , the resonance frequency (kHz) of the first vibration plate 110 is represented on the vertical axis, and the long side dimension L1 (mm) of the inner side of the housing 120 is represented on the horizontal axis. As simulation analysis conditions, the short side dimension L2 of the inner side of the housing 120 is fixed at 2 mm.

[0076] As Figure 8As shown, when the long side dimension L1 of the inner side of the housing 120 is 2 mm, the resonance frequency of the first diaphragm 110 is 220 kHz. When the long side dimension L1 increases to 8 mm and the long side dimension of the vibration region of the first diaphragm 110 increases, the resonance frequency of the first diaphragm 110 decreases to 122 kHz. After that, even when the long side dimension L1 of the inner side of the housing 120 is larger than 8 mm and the long side dimension of the vibration region of the first diaphragm 110 further increases, the resonance frequency of the first diaphragm 110 remains approximately constant at 122 kHz.

[0077] That is to say, although the resonance frequency of the first diaphragm 110 is determined by the speed of sound in the first diaphragm 110 and the reflection of the vibration with the housing 120 set as a fixed end, the following situation starts to occur when the long side dimension L1 of the inner side of the housing 120 is more than 4 times the short side dimension L2: for the reflection of the vibration, the influence of the short side dimension L2 becomes dominant, and even when the long side dimension L1 further increases relative to 4 times the short side dimension L2, the state of the reflection of the vibration remains unchanged.

[0078] Next, the relationship between the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer 100 and the long side dimension L1 of the inner side of the housing 120 will be described for the results obtained by simulation analysis using the finite element method.

[0079] Figure 9 is a graph that uses the finite element method to simulate and analyze the change in the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer when the short side dimension of the inner side of the housing is fixed and the long side dimension changes. In Figure 9 the vertical axis represents the sound pressure (Pa) transmitted from the ultrasonic transducer 100, and the horizontal axis represents the long side dimension L1 (mm) of the inner side of the housing 120. As the simulation analysis conditions, the short side dimension L2 of the inner side of the housing 120 is fixed at 2 mm, and the sound pressure (Pa) at a position 30 cm away from the first diaphragm 110 on the front side of the ultrasonic transducer 100 in the third direction (Z-axis direction) is calculated.

[0080] As Figure 9 shown, as the long side dimension L1 of the inner side of the housing 120 increases, the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer 100 increases. This means that even when the long side dimension of the vibration region of the first diaphragm 110 is increased, the entire vibration region of the first diaphragm 110 between the two end portions 110e vibrates. That is, the area of the vibration region can be increased by the amount by which the vibration region of the first diaphragm 110 becomes longer. As a result, the pressure change of the air achieved by the vibration of the first diaphragm 110 can be increased, thereby obtaining a higher sound pressure.

[0081] Thus, the ultrasonic transducer 100 of the present embodiment can increase the long side dimension of the vibration region of the first vibration plate 110, thereby maintaining the resonance frequency at a substantially constant level while increasing the sound pressure. In addition, nodes exist at both ends in the long side direction, so these two ends can be supported or fixed, making it easier to install the ultrasonic transducer 100.

[0082] Next, the relationship between the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer and the minimum dimension Lm in the second direction (Y-axis direction) of the piezoelectric body 131 will be described with respect to the results obtained by performing simulation analysis using the finite element method.

[0083] Figure 10 It is a graph that uses the finite element method to simulate and analyze the change in the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer when the minimum dimension in the second direction (Y-axis direction) of the ultrasonic oscillator changes. In Figure 10 it, the sound pressure (Pa) transmitted from the ultrasonic transducer is represented on the vertical axis, and the minimum dimension Lm (mm) in the second direction (Y-axis direction) of the piezoelectric body is represented on the horizontal axis.

[0084] As the simulation analysis conditions, the dimension in the second direction (Y-axis direction) of the outer shape of the housing 120 is set to 24 mm, the dimension in the first direction (X-axis direction) is set to 2.6 mm, the thickness in the third direction (Z-axis direction) of the housing 120 is set to 0.4 mm, the long side dimension L1 inside the housing 120 is set to 20 mm, and the short side dimension L2 is set to 1.8 mm. The dimensions of the outer shape of the first vibration plate 110 are set to be the same as those of the outer shape of the housing 120, and the thickness of the first vibration plate 110 is set to 0.1 mm. The dimension of the piezoelectric body 131 in the first direction (X-axis direction) is set to 2.4 mm, and the thickness of the piezoelectric body 131 is set to 0.1 mm. The piezoelectric body 131 is arranged at a position that is point-symmetrical about the center of the housing 120 when viewed from the third direction (Z-axis direction). The dimension of the second vibration plate 135 in the first direction (X-axis direction) is set to 1.5 mm, and the thickness of the second vibration plate 135 is set to 0.2 mm. The dimensions of the piezoelectric body 131 and the second vibration plate 135 in the second direction (Y-axis direction) are set to be the same. The sound pressure (Pa) at a position 30 cm away from the first vibration plate 110 on the front surface of the ultrasonic transducer in the third direction (Z-axis direction) is calculated.

[0085] Figure 11 It is a three-dimensional view showing the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer of the first embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 24 mm, transmits or receives ultrasonic waves. Figure 12It is a three-dimensional diagram of the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer of the second embodiment, where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 16 mm, transmits or receives ultrasonic waves. Figure 13 It is a three-dimensional diagram of the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer of the third embodiment, where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 15 mm, transmits or receives ultrasonic waves. Figure 14 It is a three-dimensional diagram of the displacement state obtained by performing simulation analysis using the finite element method when the ultrasonic transducer of the fourth embodiment, where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body is 14.5 mm, transmits or receives ultrasonic waves. Figure 15 It is a cross-sectional view of the ultrasonic transducer viewed from the arrow direction of the XV-XV line. Figure 14 of the ultrasonic transducer.

[0086] As Figure 11 and Figure 12 shown, in the ultrasonic transducers 101 of the first embodiment and 102 of the second embodiment where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body 131 is 16 mm or more, the first diaphragm 110 vibrates in a tuning fork vibration mode in which the middle portion 110c of the first diaphragm 110 becomes an antinode of resonant vibration. As Figure 13 shown, in the ultrasonic transducer 103 of the third embodiment where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body 131 is 15 mm, the first diaphragm 110 vibrates in the following vibration mode: large displacement portions 110p with the largest displacement appear near both ends in the long side direction inside the housing 120 in the first diaphragm 110. Among them, the two large displacement portions 110p vibrate in the same phase, and the vibration in the first diaphragm 110 is in the same phase.

[0087] As Figure 14 and Figure 15 shown, in the ultrasonic transducer 104 of the fourth embodiment where the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body 131 is 14.5 mm, the first diaphragm 110 vibrates in the following vibration mode: reverse displacement portions 110b that are displaced in a displacement direction Ds opposite to the displacement direction Dm of the middle portion 110c appear near both ends in the long side direction inside the housing 120 in the first diaphragm 110. That is, in the first diaphragm 110, vibrations with a phase opposite to that of the middle portion 110c are generated near both ends in the long side direction inside the housing 120.

[0088] As a result, as Figure 10As shown, the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer 104 of the fourth embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body 131 is 14.5 mm, becomes approximately half of the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer 102 of the second embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the piezoelectric body 131 is 16 mm.

[0089] In the ultrasonic transducer 104 of the fourth embodiment, the average distance L3 in the second direction (Y-axis direction) of the gap between at least one end edge 120e in the second direction (Y-axis direction) of the inner peripheral surface 120s of the housing 120 and at least one end edge 130e in the second direction (Y-axis direction) of the surface 130s of the single crystal wafer type piezoelectric vibrator 130 on the side of the housing 120 is 2.75 mm, which is approximately 1.5 times the short side dimension L2 in the first direction (X-axis direction) inside the housing 120. That is, when the above average distance L3 is approximately 1.5 times the short side dimension L2 in the first direction (X-axis direction) inside the housing 120, vibrations with opposite phases are generated in the first diaphragm 110.

[0090] It was confirmed by simulation analysis using the finite element method that although there are slight variations due to changes in the dimension of the length of the single crystal wafer type piezoelectric vibrator 130 in the second direction (Y-axis direction) and the short side dimension L2 in the first direction (X-axis direction) inside the housing 120, if the above average distance L3 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the housing 120, vibrations with opposite phases are not generated in the first diaphragm 110. That is, if the above average distance L3 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the housing 120, the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer can be maintained at a high level and the power consumption can be reduced.

[0091] Here, the power consumption of the ultrasonic transducer will be described. The piezoelectric body 131 that constitutes the single crystal wafer type piezoelectric vibrator 130, especially the piezoelectric ceramic, has a large dielectric constant and has electrical characteristics like a capacitor. If the frequencies of the alternating current are set to ω and the capacitance is set to C, the impedance of the capacitance is proportional to 1 / ωC. Therefore, if the frequency of the applied voltage to the piezoelectric body 131 becomes higher, the impedance of the piezoelectric body 131 decreases and the consumed current increases. On the other hand, if the area of the piezoelectric body 131 is reduced, the capacitance decreases, so the consumed current becomes smaller.

[0092] In the ultrasonic transducer 101 of the first embodiment, in which the minimum dimension in the second direction (Y-axis direction) of the single crystal wafer type piezoelectric vibrator 130 is 24 mm, as Figure 11As shown, the end portions 110e at both ends in the long side direction on the inner side of the frame 120 in the first diaphragm 110 become nodes of resonant vibration and hardly vibrate. That is, both end portions of the single crystal wafer type piezoelectric vibrator 130 in the second direction (Y-axis direction) hardly vibrate and do not operate.

[0093] Therefore, in the present embodiment, as Figure 4 shown, at least one end edge 120e in the second direction (Y-axis direction) of the inner peripheral surface 120s of the frame 120 and Figure 2 shown, a gap is formed between at least one end edge 130e in the second direction (Y-axis direction) of the surface 130s on the side of the frame 120 of the piezoelectric body 131, so that the minimum dimension Lm in the second direction (Y-axis direction) of the piezoelectric body 131 is smaller than the long side dimension L1 in the second direction (Y-axis direction) of the inside of the frame 120. Thereby, it is possible to eliminate Figure 11 shown as the parts that consume power and do not operate, both end portions of the single crystal wafer type piezoelectric vibrator 130 in the second direction (Y-axis direction), and it is possible to reduce the power consumption of the single crystal wafer type piezoelectric vibrator 130 and improve the efficiency.

[0094] In addition, by forming the above-mentioned gap, the internal space inside the frame 120 and the external space outside the frame 120 communicate with each other through the above-mentioned gap. Therefore, for example, it is possible to reduce the pressure change in the internal space when heating and curing the adhesive material that joins the first diaphragm 110 and the frame 120, thereby suppressing the increase in the internal stress in the ultrasonic transducer 100. When the first diaphragm 110 and the frame 120 are joined by an adhesive material, in order to prevent the above-mentioned gap from being blocked by the adhesive material applied to the long side portion 121 of the frame 120 and entering the above-mentioned gap, the average distance L3 in the second direction (Y-axis direction) of the above-mentioned gap is preferably 0.2 mm or more. That is, the average distance L3 in the second direction (Y-axis direction) of the above-mentioned gap is preferably 0.2 mm or more and is 1.3 times or less of the short side dimension L2 in the first direction (X-axis direction) of the inside of the frame 120.

[0095] Figure 16 It is a view of the ultrasonic transducer according to the fifth embodiment of the first embodiment of the present invention as viewed from the ultrasonic oscillator side. As Figure 16As shown, in the ultrasonic transducer 105 of the fifth embodiment of Embodiment 1 of the present invention, the average distance L3 in the second direction (Y-axis direction) of the gap between the edge 120e on one side in the second direction (Y-axis direction) of the inner peripheral surface 120s of the housing 120 and the edge 130e on one side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric vibrator 130 on the side of the housing 120 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the housing 120, and no gap is formed between the edge 120e on the other side in the second direction (Y-axis direction) of the inner peripheral surface 120s of the housing 120 and the edge 130e on the other side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric vibrator 130. That is, it is also possible to eliminate only Figure 11 one of the two end portions in the second direction (Y-axis direction) of the single-chip piezoelectric vibrator 130 shown as a portion that consumes power and does not operate.

[0096] Figure 17 is a view of the ultrasonic transducer of the sixth embodiment of Embodiment 1 of the present invention as viewed from the ultrasonic vibrator side. As Figure 17 shown, in the ultrasonic transducer 106 of the sixth embodiment of Embodiment 1 of the present invention, when viewed from the third direction (Z-axis direction), the edge 130e on one side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric vibrator 130 on the side of the housing 120 is located at a position not parallel to at least one edge 120e in the second direction (Y-axis direction) of the inner peripheral surface 120s of the housing 120. In such a case, the average distance L3 in the second direction (Y-axis direction) of the gap between at least one edge 120e in the second direction (Y-axis direction) of the inner peripheral surface 120s of the housing 120 and Figure 2 the edge 130e on one side in the second direction (Y-axis direction) of the surface 130s of the piezoelectric body 131 of the single-chip piezoelectric vibrator 130 shown is set as the average value of the shortest distances between the edge 120e and the edge 130e that vary according to the position in the first direction (X-axis direction), and this average distance L3 only needs to be 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the housing 120.

[0097] Figure 18 is a cross-sectional view showing the structure of the ultrasonic transducer of the seventh embodiment of Embodiment 1 of the present invention. As Figure 18As shown, the average distance L3 in the second direction (Y-axis direction) of the gap between at least one end edge 120e in the second direction (Y-axis direction) of the inner peripheral surface of the housing 120 and at least one end edge 130e in the second direction (Y-axis direction) of the surface 130s of the single crystal wafer type piezoelectric vibrator 130 on the side of the housing 120 is 1.3 times or less the short side dimension L2 in the first direction (X-axis direction) inside the housing 120. Thus, in the ultrasonic transducer 100d, it is possible to reduce power consumption and increase the sound pressure level with a simple and miniaturized structure.

[0098] A part of the surface 131b of the piezoelectric body 131 on the side opposite to the side where the housing 120 is located is not covered by the second vibration plate 135. Specifically, by arranging the second vibration plate 135 to be offset from the piezoelectric body 131 in the second direction (Y-axis direction), a part of the surface 131b of the piezoelectric body 131 on the side opposite to the side where the housing 120 is located is not covered by the second vibration plate 135 but is exposed. Thus, it is possible to easily connect the wiring 10 for supplying power to the piezoelectric body 131 to a part of the surface 131b of the piezoelectric body 131 on the side opposite to the side where the housing 120 is located and not covered by the second vibration plate 135. In addition, the dimension of the second vibration plate 135 in the second direction (Y-axis direction) can be larger, smaller, or the same as the dimension of the piezoelectric body 131 in the second direction (Y-axis direction).

[0099] Here, regarding the relationship between the average distance D1 in the first direction (X-axis direction) between one end edge 120s1 in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 and one end edge 135s1 in the first direction (X-axis direction) of the second vibration plate 135, and the average distance D2 in the first direction (X-axis direction) between the other end edge 120s2 in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 and the other end edge 135s2 in the first direction (X-axis direction) of the second vibration plate 135 and the displacement of the first vibration plate 110, the results of the first experimental example obtained from the simulation analysis will be described.

[0100] Figure 19 is a graph that uses the finite element method to simulate and analyze the change in the displacement of the first vibration plate when the center position of the second vibration plate in the first direction (X-axis direction) is fixed and the short side dimension W of the second vibration plate changes in the first experimental example. In Figure 19 the vertical axis represents the displacement (μm) of the first vibration plate 110, and the horizontal axis represents the short side dimension W (mm) of the second vibration plate.

[0101] As the simulation analysis conditions in the first experimental example, the thickness of the first vibrating plate 110 in the third direction (Z-axis direction) is set to 0.1 mm, the long side dimension of the piezoelectric body 131 in the second direction (Y-axis direction) is set to 18 mm, the thickness of the piezoelectric body 131 in the third direction (Z-axis direction) is set to 0.1 mm, the long side dimension L1 of the inner side of the housing 120 is set to 20 mm, the short side dimension L2 is set to 1.8 mm, the thickness of the housing 120 in the third direction (Z-axis direction) is set to 0.4 mm, the thickness of the second vibrating plate 135 in the third direction (Z-axis direction) is set to 0.2 mm, and the long side dimension of the second vibrating plate 135 in the second direction (Y-axis direction) is set to 18 mm. The material of the first vibrating plate 110 is set to aluminum alloy, the material of the housing 120 is set to stainless steel, and the material of the second vibrating plate 135 is set to a nickel-iron alloy (42Ni-Fe). The central position of the second vibrating plate 135 in the first direction (X-axis direction) is made to coincide with the central position of the inner space of the housing 120 in the first direction (X-axis direction).

[0102] Figure 20 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the first comparative example transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1 mm, and the average distances D1 and D2 are 0.4 mm respectively in the first experimental example.

[0103] Figure 21 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the eighth embodiment transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.5 mm, and the average distances D1 and D2 are 0.15 mm respectively in the first experimental example.

[0104] Figure 22 is a cross-sectional view showing the displacement state obtained by performing a simulation analysis using the finite element method when the ultrasonic transducer of the second comparative example transmits or receives ultrasonic waves, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 2 mm, and the average distances D1 and D2 are -0.1 mm respectively in the first experimental example. For Figures 20 - 22 , it is illustrated in the same cross-sectional view manner as Figure 7 , and is represented by a gray scale where the higher the tensile stress in the first direction (X-axis direction), the whiter it becomes, and the higher the compressive stress in the first direction (X-axis direction), the blacker it becomes.

[0105] As Figure 19As shown, in the first experimental example, when the short-side dimension W in the first direction (X-axis direction) of the second diaphragm is 1.2 mm or more and 1.8 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first diaphragm 110 at a relatively high level of 0.56 μm or more within the range where the resonance frequency is 150 kHz or more and 160 kHz or less, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0106] As Figure 20 shown, when the average distance D1 and the average distance D2 are 0.3 mm or more respectively, for the stress distribution in the piezoelectric body 131, the portions where tensile stress is generated and the portions where compressive stress is generated are dispersed, the vibration efficiency of the piezoelectric body 131 is reduced, and the displacement of the first diaphragm 110 is small.

[0107] As Figure 21 shown, when the average distance D1 and the average distance D2 are 0 or more and 0.3 mm or less respectively, for the stress distribution in the piezoelectric body 131, portions where relatively high compressive stress is generated exist as a whole, the vibration efficiency of the piezoelectric body 131 is improved, and the displacement of the first diaphragm 110 is large.

[0108] As Figure 22 shown, when viewed from the third direction (Z-axis direction) orthogonal to the first diaphragm 110, when the second diaphragm 135 extends beyond the region sandwiched by the two end edges in the first direction (X-axis direction) of the inner peripheral surface of the housing 120 and is located outside this region in the first direction (X-axis direction), the piezoelectric body 131 is restricted and difficult to vibrate, and the stress in the piezoelectric body 131 is generally low. As a result, the vibration efficiency of the piezoelectric body 131 is reduced, and the displacement of the first diaphragm 110 is small.

[0109] According to Figures 20 - 22 the mechanism of action shown, when the central position in the first direction (X-axis direction) of the second diaphragm 135 coincides with the central position in the first direction (X-axis direction) of the inner space of the housing 120, in the second diaphragm 135, when the average distance D1 and the average distance D2 are each 1 / 6 or less of the short-side dimension L2 in the first direction (X-axis direction) inside the housing 120, it is considered that the displacement of the first diaphragm 110 is large, and the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100 can be improved.

[0110] Hereinafter, the results obtained by analyzing by changing the simulation analysis conditions with respect to the first experimental example will be described. For the following analysis results, only the conditions changed with respect to the first experimental example are described, and the conditions not described are the same as the analysis conditions of the first experimental example.

[0111] Figure 23It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibration plate when, in the second experimental example, the thickness of the piezoelectric body is changed to 0.2 mm relative to the analysis conditions of the first experimental example, the center position of the second vibration plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibration plate is changed.

[0112] As Figure 23 shown, in the second experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibration plate is 1.2 mm or more and 1.8 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first vibration plate 110 at a relatively high level of 0.31 μm or more within the range where the resonance frequency is 158 kHz or more and 159 kHz or less, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0113] Figure 24 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibration plate when, in the third experimental example, the thickness of the second vibration plate is changed to 0.3 mm relative to the analysis conditions of the first experimental example, the center position of the second vibration plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibration plate is changed.

[0114] As Figure 24 shown, in the third experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibration plate is 1.2 mm or more and 1.8 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first vibration plate 110 at a relatively high level of 0.55 μm or more within the range where the resonance frequency is 150 kHz or more and 160 kHz or less, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0115] Figure 25 It is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibration plate when, in the fourth experimental example, the short side dimension inside the frame is changed to 2.2 mm relative to the analysis conditions of the first experimental example, the center position of the second vibration plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibration plate is changed.

[0116] As Figure 25As shown, in the fourth experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.6 mm or more and 2.2 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first vibrating plate 110 at a relatively high level of 0.65 μm or more within the range where the resonance frequency is 100 kHz or more and 110 kHz or less, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0117] Figure 26 It is a graph that uses the finite element method to simulate and analyze the change in the displacement of the first vibrating plate when, in the fifth experimental example, the thickness of the piezoelectric body is changed to 0.2 mm, the short side dimension inside the frame is changed to 2.2 mm, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0118] As Figure 26 shown, in the fifth experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.6 mm or more and 2.2 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first vibrating plate 110 at a relatively high level of 0.44 μm or more when the resonance frequency is 108 kHz, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0119] Figure 27 It is a graph that uses the finite element method to simulate and analyze the change in the displacement of the first vibrating plate when, in the sixth experimental example, the material of the second vibrating plate is changed to piezoelectric ceramics, the center position of the second vibrating plate in the first direction (X-axis direction) is fixed, and the short side dimension W of the second vibrating plate is changed.

[0120] As Figure 27 shown, in the sixth experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.2 mm or more and 1.8 mm or less, that is, when the average distance D1 and the average distance D2 are 0 mm or more and 0.3 mm or less respectively, it is possible to ensure the displacement of the first vibrating plate 110 at a relatively high level of 0.55 μm or more within the range where the resonance frequency is 150 kHz or more and 160 kHz or less, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0121] Next, the results of the seventh experimental example, which uses the finite element method to simulate and analyze the change in the displacement of the first vibrating plate when the center position of the second vibrating plate in the first direction (X-axis direction) is offset and the short side dimension W of the second vibrating plate is changed, will be described.

[0122] Figure 28 This is a graph that uses the finite element method to simulate and analyze the displacement trend of the first vibrating plate when the center position of the second vibrating plate in the first direction (X-axis direction) is offset in the 7th experimental example. In Figure 28 , the displacement (μm) of the first vibrating plate 110 is represented on the vertical axis, and the offset amount (mm) of the center position of the second vibrating plate in the first direction (X-axis direction) is represented on the horizontal axis. In Figure 28 , the data with the short side dimension W of the second vibrating plate being 1.5 mm is represented by a solid line, the data with the short side dimension W of the second vibrating plate being 1.4 mm is represented by a dashed line, the data with the short side dimension W of the second vibrating plate being 1.3 mm is represented by a single dotted line, and the data with the short side dimension W of the second vibrating plate being 1.2 mm is represented by a double dotted line.

[0123] As the simulation analysis conditions in the 7th experimental example, other conditions are the same as those in the 1st experimental example. In addition, the offset direction of the center position of the second vibrating plate is set to one side in the first direction (X-axis direction), and the center position of the second vibrating plate is offset until the average distance D1 becomes 0 mm.

[0124] Figure 29 This is a cross-sectional view of the displacement state obtained by using the finite element method for simulation analysis when the ultrasonic transducer of the 9th embodiment, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.5 mm, the offset amount of the center position of the second vibrating plate in the first direction (X-axis direction) is 0.15 mm, the average distance D1 is 0 mm, and the average distance D2 is 0.3 mm, transmits or receives ultrasonic waves in the 7th experimental example.

[0125] Figure 30 This is a cross-sectional view of the displacement state obtained by using the finite element method for simulation analysis when the ultrasonic transducer of the 3rd comparative example, where the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.2 mm, the offset amount of the center position of the second vibrating plate in the first direction (X-axis direction) is 0.3 mm, the average distance D1 is 0 mm, and the average distance D2 is 0.6 mm, transmits or receives ultrasonic waves in the 7th experimental example.

[0126] As Figure 28 shown, in the 7th experimental example, when the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.2 mm, when the offset amount of the center position of the second vibrating plate in the first direction (X-axis direction) is 0 mm, that is, when the average distances D1 and D2 are 0.3 mm respectively, it is possible to ensure the displacement of the first vibrating plate 110 at a relatively high level of 0.56 μm or more, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0127] When the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.3 mm, when the offset amount at the center position in the first direction (X-axis direction) of the second vibrating plate is within 0.1 mm, that is, when the average distance D2 is within 0.35 mm, the displacement of the first vibrating plate 110 can be ensured at a relatively high level of 0.56 μm or more, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0128] When the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.4 mm, when the offset amount at the center position in the first direction (X-axis direction) of the second vibrating plate is within 0.15 mm, that is, when the average distance D2 is within 0.35 mm, the displacement of the first vibrating plate 110 can be ensured at a relatively high level of 0.56 μm or more, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0129] When the short side dimension W in the first direction (X-axis direction) of the second vibrating plate is 1.5 mm, when the offset amount at the center position in the first direction (X-axis direction) of the second vibrating plate is within 0.15 mm, that is, when the average distance D2 is within 0.3 mm, the displacement of the first vibrating plate 110 can be ensured at a relatively high level of 0.56 μm or more, improving the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100.

[0130] As Figure 29 shown, when the average distance D2 is 0.3 mm, for the stress distribution in the piezoelectric body 131, a relatively high compressive stress is generated in the part on the second vibrating plate 135, and a relatively high tensile stress is generated in the part corresponding to the average distance D2, but the vibration mode is maintained, and no significant reduction in the displacement of the first vibrating plate 110 is confirmed.

[0131] As Figure 30 shown, when the average distance D2 is 0.6 mm, for the stress distribution in the piezoelectric body 131, a relatively high compressive stress is generated in the part on the second vibrating plate 135, and a relatively high tensile stress is generated in the part corresponding to the average distance D2, the vibration mode changes and the first vibrating plate 110 deforms in a skewed shape, and a significant reduction in the displacement of the first vibrating plate 110 is confirmed.

[0132] According to Figure 29 and Figure 30Regarding the operation mechanism shown, when the central position of the second diaphragm 135 in the first direction (X-axis direction) is offset from the central position of the inner space of the housing 120 in the first direction (X-axis direction), it is considered that if the average distance D1 and the average distance D2 are each 1 / 6 or less of the short side dimension L2 of the inner side of the housing 120 in the first direction (X-axis direction), the displacement of the first diaphragm 110 can be ensured at a relatively high level of 0.56 μm or more, and the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100 can be improved.

[0133] Based on the results of the above-described first to seventh experimental examples, it is considered that when the second diaphragm 135 is located in the region sandwiched between the two end edges of the inner peripheral surface of the housing 120 in the first direction (X-axis direction) when viewed from the third direction (Z-axis direction) orthogonal to the first diaphragm 110, and in the second diaphragm 135, the average distance D1 in the first direction (X-axis direction) between one end edge 120s1 of the inner peripheral surface of the housing 120 in the first direction (X-axis direction) and one end edge 135s1 of the second diaphragm 135 in the first direction (X-axis direction), and the average distance D2 in the first direction (X-axis direction) between the other end edge 120s2 of the inner peripheral surface of the housing 120 in the first direction (X-axis direction) and the other end edge 135s2 of the second diaphragm 135 in the first direction (X-axis direction) are each 1 / 6 or less of the short side dimension L2 of the inner side of the housing 120 in the first direction (X-axis direction), the displacement of the first diaphragm 110 can be increased, and the transmission sound pressure and reception sensitivity of the ultrasonic transducer 100 can be improved.

[0134] In the parametric speaker including the ultrasonic transducer 100 according to Embodiment 1 of the present invention, audible sound can be reproduced by modulating the ultrasonic waves radiated from the ultrasonic transducer 100 through the modulation drive of the ultrasonic transducer 100. As the modulation method, there are an AM modulation method (amplitude modulation method) and an FM modulation method (frequency modulation method).

[0135] Figure 31 It is a perspective view of the ultrasonic transducer according to the first modification of Embodiment 1 of the present invention as viewed from the second diaphragm side. As Figure 31As shown, in the ultrasonic transducer 100a according to the first modification of Embodiment 1 of the present invention, the length of the second diaphragm 135 in the second direction (Y-axis direction) is longer than the length of the piezoelectric body 131 in the second direction (Y-axis direction). The housing 120 and the second diaphragm 135 are each plated with Ag or the like. The housing 120 and the piezoelectric body 131 are electrically connected by pressure bonding, and the piezoelectric body 131 and the second diaphragm 135 are electrically connected by pressure bonding. Thus, the wiring 10 for supplying power to the piezoelectric body 131 can be easily connected to the ends of the housing 120 and the second diaphragm 135 in the second direction (Y-axis direction).

[0136] Figure 32 is a perspective view of the ultrasonic transducer according to the second modification of Embodiment 1 of the present invention as viewed from the first diaphragm side. As Figure 32 shown, in the ultrasonic transducer 100b according to the second modification of Embodiment 1 of the present invention, a slit 110s extending in the first direction (X-axis direction) is formed in the first diaphragm 110. In this modification, the length dimension of the slit 110s in the first direction (X-axis direction) is the same as the short side dimension L2 of the inner side of the housing 120 in the first direction (X-axis direction). The width dimension of the slit 110s in the second direction (Y-axis direction) is 0.4 mm or more and 0.6 mm or less. The slit 110s is formed from a position on the edge of the inner peripheral surface of the housing 120 in the second direction (Y-axis direction) to an inner position in the second direction (Y-axis direction) with the above width dimension. The two slits 110s are respectively opened at both ends of the housing 120 in the second direction (Y-axis direction) on the inner side.

[0137] Thus, the internal space inside the housing 120 and the external space outside the housing 120 communicate with each other through the slit 110s. Therefore, for example, it is possible to reduce the pressure change in the internal space when heating and curing the adhesive material that joins the first diaphragm 110 and the housing 120, thereby suppressing an increase in the internal stress in the ultrasonic transducer 100. In addition, the portion adjacent to the slit 110s becomes the free end of the first diaphragm 110 that resonates and vibrates and is easily displaced. Therefore, it is possible to reduce the internal stress generated in the resonating and vibrating first diaphragm 110. Thus, in the ultrasonic transducer 100, it is possible to reduce the internal stress and improve the sound pressure level with a simple and miniaturized structure.

[0138] (Embodiment 2)

[0139] Hereinafter, the ultrasonic transducer according to Embodiment 2 of the present invention will be described with reference to the drawings. In the ultrasonic transducer according to Embodiment 2 of the present invention, it is different from the ultrasonic transducer according to Embodiment 1 of the present invention in that a plurality of single-chip piezoelectric vibrators are arranged in an array, and thus, the structures that are the same as those of the ultrasonic transducer according to Embodiment 1 of the present invention will not be described repeatedly.

[0140] Figure 33 It is a side view showing the structure of the ultrasonic transducer according to Embodiment 2 of the present invention. Figure 34 It is viewed from the direction of arrow XXXIV Figure 33 The rear view of the ultrasonic transducer shown. Figure 35 It is an exploded perspective view showing the stacked state of the respective structures of the ultrasonic transducer according to Embodiment 2 of the present invention.

[0141] As Figures 33 - 35 shown, in the ultrasonic transducer 200 according to Embodiment 2 of the present invention, the ultrasonic transducer 100 according to Embodiment 1 arranged in an array in the first direction (X-axis direction) is integrally formed. The ultrasonic transducer 200 includes a first vibration plate 210, a plurality of frames 220, and a plurality of single-chip piezoelectric vibrators 230. A plurality of frames 220 are joined to the first vibration plate 210, and a plurality of single-chip piezoelectric vibrators 230 are respectively joined to the plurality of frames 220.

[0142] Here, a manufacturing method of the ultrasonic transducer 200 will be described. As Figure 35 shown, the first vibration plate 210 has a flat plate shape, and a plurality of slits 211 extending in the second direction (Y-axis direction) are formed at intervals in the first direction (X-axis direction). The first vibration plate 210 is formed of an aluminum alloy such as duralumin containing aluminum, or a metal such as stainless steel. In the present embodiment, the first vibration plate 210 is formed of stainless steel. The plurality of slits 211 are formed by etching or cutting or the like.

[0143] The plurality of frames 220 each have a rectangular ring shape. The plurality of frames 220 each have a short side direction along the first direction (X-axis direction) and a long side direction along the second direction (Y-axis direction). The plurality of frames 220 each extend in the second direction (Y-axis direction). The axial directions of the plurality of frames 220 each extend along the third direction (Z-axis direction). The plurality of frames 220 each have a pair of long side portions 221 extending in the second direction (Y-axis direction) and a pair of short side portions 222 extending in the first direction (X-axis direction). The shortest distance between the long side portions 221 is more than 4 times the shortest distance between the short side portions 222.

[0144] A plurality of frames 220 are arranged and configured in the first direction (X-axis direction). Slits 223 are formed between the frames 220 adjacent to each other along the first direction (X-axis direction). The plurality of slits 223 are formed by etching, cutting, or the like. The adjacent long side portions 221 of the frames 220 adjacent to each other along the first direction (X-axis direction) are separated from each other by the slits 223.

[0145] The frames 220 adjacent to each other in the first direction (X-axis direction) are connected to each other at the short side portions 222. That is, the frames 220 adjacent to each other in the short side direction among the plurality of frames 220 are connected to each other at both ends in the long side direction of each other.

[0146] The plurality of frames 220 are each formed of a metal such as aluminum alloy or stainless steel, a glass epoxy material, or a resin. In the present embodiment, the plurality of frames 220 are formed of a single thin plate, but are not limited thereto, and may also be integrated by joining the short side portions 222 of the plurality of frames 220 respectively formed of a plurality of thin plates to each other.

[0147] Figure 36 It is a plan view showing the positional relationship in the first direction (X-axis direction) in the process of cutting the piezoelectric body of the ultrasonic transducer according to Embodiment 2 of the present invention. As Figure 36 shown, the slit 211 and the slit 223 are arranged at the same position in the first direction (X-axis direction) so as to overlap each other in the third direction (Z-axis direction). The piezoelectric body 131 is cut and divided by a cutting machine or the like at a plurality of cutting lines LC extending along the second direction (Y-axis direction) so as to overlap the slit 211 and the slit 223 in the third direction (Z-axis direction).

[0148] As Figure 35 shown, the second vibration plates 235 adjacent to each other in the first direction (X-axis direction) are connected to each other at positions near both ends in the second direction (Y-axis direction) by connecting portions 236. The connecting portions 236 extend in the first direction (X-axis direction). The connecting portions 236 are formed by etching, stamping, cutting, or the like.

[0149] A concave portion 237 is formed in a portion of the connecting portion 236 that faces the gap between the piezoelectric bodies 131 adjacent to each other in the first direction (X-axis direction) among the plurality of single crystal wafer type piezoelectric vibrators 230. The concave portion 237 is formed by semi-etching, stamping, cutting, or the like.

[0150] The second vibration plate 235 and the piezoelectric body 131 are joined by an adhesive so that the concave portion 237 faces the cutting line LC in the third direction (Z-axis direction). As a result, as Figure 34As shown, a plurality of single-chip piezoelectric vibrators 230 each include a piezoelectric body 131 facing the first vibration plate 210 with a space therebetween, and a plurality of second vibration plates 235 provided on the side of the piezoelectric body 131 opposite to the side where the housing 220 is located. The plurality of single-chip piezoelectric vibrators 230 are arranged in the first direction (X-axis direction).

[0151] The recess 237 functions as a storage place for the adhesive, suppressing the entry of the adhesive into the cutting line LC. Thereby, it is possible to suppress the characteristics deterioration of the ultrasonic transducer 200 caused by the interference between adjacent single-chip piezoelectric vibrators 230.

[0152] In the present embodiment, the housing 220 and the second vibration plate 235 are each plated with Ag or the like. The housing 220 and the piezoelectric body 131 are electrically connected by pressure bonding, and the piezoelectric body 131 and the second vibration plate 235 are electrically connected by pressure bonding. Thus, as Figure 34 shown, it is possible to drive a plurality of single-chip piezoelectric vibrators 230 by connecting the wiring 10 for supplying power to the piezoelectric body 131 only to two portions at the ends in the second direction (Y-axis direction) of the housing 220 and the second vibration plate 235, respectively.

[0153] In the ultrasonic transducer 100 of Embodiment 1, nodes exist at both end portions in the second direction (Y-axis direction) which is the long side direction. Therefore, even if the ultrasonic transducers 100 of Embodiment 1 are arrayed by connecting them to each other at these both end portions to form the ultrasonic transducer 200 of Embodiment 2, the resonance vibration in each ultrasonic transducer 100 is not hindered. Therefore, it is possible to easily increase the sound pressure level by increasing the number of ultrasonic transducers 100 constituting the ultrasonic transducer 200 of Embodiment 2.

[0154] In a parametric speaker including the ultrasonic transducer 200 of Embodiment 2 of the present invention, audible sound can be reproduced by modulating the ultrasonic waves radiated from the ultrasonic transducer 200 by the modulation drive of the ultrasonic transducer 200.

[0155] In a parametric speaker including the ultrasonic transducer 200 of the present embodiment that transmits ultrasonic waves of 100 kHz or more, it is possible to suppress the sound from reaching an unnecessary distance, and to suppress the sound leakage caused by unnecessary reflection, and to reproduce audible sound only in a limited space. In addition, in the ultrasonic transducer 200, it is possible to increase the attenuation of the audible sound achieved by the propagation distance without providing a structure for transmitting an anti-phase carrier as in Patent Document 2, and thus a simple and miniaturized structure can be provided. Moreover, ultrasonic waves of 100 kHz or more are outside the audible range of animals such as dogs or cats, so the influence on these animals can be suppressed.

[0156] In order to attenuate audible sound after a propagation distance of 30 cm, the Rayleigh distance needs to be set within 30 cm. The Rayleigh distance R0 satisfies the relationship R0 = (k × a 2 ) / 2. k is the wave number and a is the radius of the sound source. Therefore, when the speed of sound in air is set to 340 m / s, the long side dimension of the vibration region of the first vibrating plate 210 is 36 mm or less when the ultrasonic frequency is 100 kHz, 29.4 mm or less when the ultrasonic frequency is 150 kHz, and 25.5 mm or less when the ultrasonic frequency is 200 kHz. When the ultrasonic frequency is 100 kHz or more, the long side dimension L1 is 4 times or more and 24 times or less the short side dimension L2.

[0157] (Appendix)

[0158] Those skilled in the art can understand that the above exemplary embodiments are specific examples of the following forms.

[0159] <1> An ultrasonic transducer, comprising:

[0160] A first vibrating plate;

[0161] At least one frame body that extends in the long side direction and is joined to the first vibrating plate; and

[0162] At least one single crystal wafer type piezoelectric vibrator, which is respectively mounted on the at least one frame body, includes a piezoelectric body that faces the first vibrating plate at an interval, and a second vibrating plate provided on the side of the piezoelectric body opposite to the side where the frame body is located,

[0163] The first vibrating plate resonantly vibrates in a direction orthogonal to the first vibrating plate with a phase opposite to that of the at least one single crystal wafer type piezoelectric vibrator,

[0164] The dimension of the at least one frame body in the long side direction inside the at least one frame body is 4 times or more the dimension of the at least one frame body in the short side direction orthogonal to the long side direction inside the at least one frame body,

[0165] When viewed in a direction orthogonal to the first diaphragm, the second diaphragm is located within a region in the short-side direction that is sandwiched by the two end edges in the short-side direction of the inner peripheral surface of the at least one housing. Further, the average distance in the short-side direction between one end edge in the short-side direction of the inner peripheral surface of the at least one housing and one end edge in the short-side direction of the second diaphragm, and the average distance in the short-side direction between the other end edge in the short-side direction of the inner peripheral surface of the at least one housing and the other end edge in the short-side direction of the second diaphragm are each 1 / 6 or less of the size of the at least one housing in the short-side direction on the inner side thereof.

[0166] <2> The ultrasonic transducer according to <1>, wherein

[0167] the size of the at least one housing in the long-side direction on the inner side thereof is larger than the minimum size of the piezoelectric body in the long-side direction of the at least one single-wafer piezoelectric vibrator,

[0168] the average distance in the long-side direction of the gap between at least one end edge in the long-side direction of the inner peripheral surface of the at least one housing and at least one end edge in the long-side direction of the surface of the piezoelectric body of the at least one single-wafer piezoelectric vibrator on the side closer to the housing is 1.3 times or less the size of the at least one housing in the short-side direction on the inner side thereof.

[0169] <3> The ultrasonic transducer according to <1> or <2>, wherein

[0170] a plurality of the at least one housing are arranged in the short-side direction and joined to the first diaphragm,

[0171] the at least one housing adjacent in the short-side direction is connected to each other at both ends in the long-side direction thereof,

[0172] a plurality of the at least one single-wafer piezoelectric vibrator are arranged in the short-side direction.

[0173] <4> The ultrasonic transducer according to <3>, wherein

[0174] the second diaphragms of the at least one single-wafer piezoelectric vibrator adjacent in the short-side direction are connected to each other at positions close to both ends in the long-side direction thereof by a connecting portion extending in the short-side direction,

[0175] a recess is formed in a portion of the connecting portion that faces the gap between the piezoelectric bodies of the at least one single-wafer piezoelectric vibrator adjacent in the short-side direction.

[0176] <5>A parametric loudspeaker including the ultrasonic transducer according to any one of <1> to <4>.

[0177] The audible sound is reproduced by the modulation driving of the ultrasonic transducer.

[0178] In the description of the above embodiments and examples, structures that can be combined may be combined with each other.

[0179] It should be considered that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is represented by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0180] Description of Reference Numerals

[0181] 10, wiring; 100, 100a, 100b, 100d, 101, 102, 103, 104, 105, 106, 200, ultrasonic transducers; 110, 210, first diaphragms; 110b, reverse displacement portions; 110c, intermediate portions; 110e, end portions; 110p, large displacement portions; 110s, 211, 223, slits; 120, 220, frames; 120e, 120s1, 120s2, 130e, 135s1, 135s2, end edges; 120s, inner circumferential surfaces; 121, 221, long side portions; 122, 222, short side portions; 130, 230, single crystal wafer type piezoelectric vibrators; 130s, 131b, surfaces; 131, piezoelectric bodies; 132, first electrodes; 133, second electrodes; 135, 235, second diaphragms; 140, processing circuits; 236, connecting portions; 237, recesses.

Claims

1. An ultrasonic transducer, comprising: A first diaphragm; At least one frame body that extends in the longitudinal direction and is joined to the first diaphragm; and At least one single-chip piezoelectric vibrator, which is respectively mounted on the at least one frame body, and includes a piezoelectric body that faces the first diaphragm with a gap therebetween and a second diaphragm provided on the side of the piezoelectric body opposite to the side where the frame body is located, The first diaphragm resonantly vibrates in a direction orthogonal to the first diaphragm with a phase opposite to that of the at least one single-chip piezoelectric vibrator, The dimension of the at least one frame body in the longitudinal direction on the inner side thereof is more than 4 times the dimension of the at least one frame body in the short-side direction orthogonal to the longitudinal direction on the inner side thereof, When viewed from a direction orthogonal to the first diaphragm, the second diaphragm is located in a region sandwiched by the two end edges of the at least one frame body in the short-side direction on the inner peripheral surface of the at least one frame body in the short-side direction. Moreover, the average distance in the short-side direction between one end edge of the at least one frame body in the short-side direction on the inner peripheral surface and one end edge of the second diaphragm in the short-side direction, and the average distance in the short-side direction between the other end edge of the at least one frame body in the short-side direction on the inner peripheral surface and the other end edge of the second diaphragm in the short-side direction are each 1 / 6 or less of the dimension of the at least one frame body in the short-side direction on the inner side thereof.

2. The ultrasonic transducer according to claim 1, wherein The dimension of the at least one frame body in the longitudinal direction on the inner side thereof is larger than the minimum dimension of the piezoelectric body in the longitudinal direction of the at least one single-chip piezoelectric vibrator, The average distance in the longitudinal direction of the gap between at least one end edge of the at least one frame body in the longitudinal direction on the inner peripheral surface and at least one end edge of the surface of the piezoelectric body of the at least one single-chip piezoelectric vibrator on the side close to the frame body is 1.3 times or less of the dimension of the at least one frame body in the short-side direction on the inner side thereof.

3. The ultrasonic transducer according to claim 1 or 2, wherein The at least one frame body is arranged in a plurality in the short-side direction and is joined to the first diaphragm, The at least one frame body adjacent in the short-side direction is connected to each other at both ends in the longitudinal direction thereof, The at least one single-chip piezoelectric vibrator is arranged in a plurality in the short-side direction.

4. The ultrasonic transducer according to claim 3, wherein The second diaphragms of the at least one single-chip piezoelectric vibrator adjacent in the short-side direction are connected to each other at positions close to both ends in the longitudinal direction by a connecting portion extending in the short-side direction, A recess is formed in a portion of the connecting portion that faces the gap between the piezoelectric bodies of the at least one single-chip piezoelectric vibrator adjacent in the short-side direction.

5. A parametric loudspeaker, comprising the ultrasonic transducer according to any one of claims 1 to 4, Reproduce audible sound by modulating and driving the ultrasonic transducer.

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