Ultrasonic device

Abstract

To suppress increase in power consumption while applying sufficient ultrasonic energy to an object.SOLUTION: An ultrasonic device 10, which irradiates an object TO with ultrasonic waves US, comprises: a vibration generation part which generates vibration corresponding to the ultrasonic waves US; and a diaphragm 62 which has a distal end face 62A irradiating the object TO with the ultrasonic wave US by transmission of the vibration. The ultrasonic device 10 abuts on the object TO, and the distance between the distal end face 62A of the diaphragm 62 and the object TO is from 0.8 n times to 1.2 n times inclusive of the half wavelength HW of the vibration (n is a natural number).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic device.

Background Art

[0002] In recent years, small ultrasonic projection devices have been used as vehicle ultrasonic devices and parametric speakers that project sound waves with directivity. For example, Japanese Patent Application Laid-Open No. 2019-97052 (hereinafter referred to as Patent Document 1) discloses an ultrasonic projection device that transmits vibrations generated by a vibrating unit to a diaphragm to project ultrasonic waves.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an ultrasonic projection device, the sound pressure of ultrasonic waves emitted into the air diffuses and rapidly weakens. Therefore, in order to apply sufficient ultrasonic energy to an object, it is necessary to increase the output of the ultrasonic projection device, which increases power consumption.

[0005] The present disclosure has been completed based on the above circumstances, and an object thereof is to suppress an increase in power consumption while applying sufficient ultrasonic energy to an object.

Means for Solving the Problems

[0006] The ultrasonic device of the present disclosure is an ultrasonic device that emits ultrasonic waves to an object, and includes a vibration generating unit that generates vibrations corresponding to the ultrasonic waves, a diaphragm having a front end surface that emits the ultrasonic waves toward the object when the vibrations are transmitted thereto, and a distance defining unit that abuts against the object and defines the distance between the front end surface of the diaphragm and the object. The distance is 0.8n times or more and 1.2n times or less (n is a natural number) the half wavelength of the vibration, and is an ultrasonic device.

Effect of the Invention

[0007] According to the present disclosure, it is possible to suppress an increase in power consumption while applying sufficient ultrasonic energy to the object.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. [1] The ultrasonic device of the present disclosure is an ultrasonic device that emits ultrasonic waves to an object, and includes a vibration generating unit that generates vibrations corresponding to the ultrasonic waves, a diaphragm having a front end surface that emits the ultrasonic waves toward the object when the vibrations are transmitted thereto, and a distance defining unit that abuts against the object and defines the distance between the front end surface of the diaphragm and the object. The distance is 0.8n times or more and 1.2 times n or less (n is a natural number) the half wavelength of the vibration, and is an ultrasonic device.

[0010] Since the distance between the front end face of the diaphragm and the object is 0.8n times or more and 1.2n times or less (n is a natural number) the half wavelength of the vibration generated by the vibration generating unit, ultrasonic waves are applied to the object where the amplitude is large. Therefore, it is possible to suppress an increase in power consumption while giving sufficient ultrasonic energy to the object.

[0011] [2] It is preferable that the distance defining portion has a cylindrical shape, at least houses the diaphragm therein, and has a tip on the side opposite to the vibration generating portion with respect to the diaphragm. When the tip of the distance defining portion is applied to the object, the distance between the front end face of the diaphragm and the object becomes 0.8n times or more and 1.2n times or less (n is a natural number) the half wavelength of the vibration generated by the vibration generating portion, so that the handling of the ultrasonic device becomes easy.

[0012] [3] It is preferable that the acoustic impedance of the distance defining portion is larger than the acoustic impedance of air. Since ultrasonic waves are likely to be reflected by the inner wall of the outer cylinder, the ultrasonic energy applied to the object can be increased.

[0013] [4] When the direction from the front end face of the diaphragm toward the object is defined as the front side, it is preferable to further include a leakage prevention member that prevents leakage of ultrasonic waves radiated rearward from the diaphragm. The leakage prevention member can prevent the ultrasonic waves radiated rearward from the diaphragm from leaking.

[0014] [Details of Embodiments of the Present Disclosure] A specific example of the ultrasonic device of the present disclosure will be described below with reference to the drawings. In each drawing, for convenience of explanation, a part of the configuration may be shown exaggerated or simplified. Also, the dimensional ratios of each part may be different in each drawing. Also, "parallel", "perpendicular", and "orthogonal" in this specification include not only cases of strict parallelism, perpendicularity, and orthogonality, but also cases that are generally parallel, perpendicular, and orthogonal within the range where the actions and effects of the present embodiment are exhibited.

[0015] (Embodiment 1) FIG. 1 is a schematic diagram showing the configuration of an ultrasonic device 10 according to Embodiment 1 of the present disclosure. The ultrasonic device 10 is a device that irradiates ultrasonic waves US into the air toward an object TO. The ultrasonic device 10 is formed in a substantially cylindrical shape with a central axis L as the axis. In the following description, for convenience of explanation, the direction in which the central axis L extends is defined as the axial direction. Also, the direction orthogonal to the central axis L is defined as the radial direction. Further, the front side is defined as the side of the first block body 21 as viewed from the second block body 22 described later in the axial direction. Also, the rear side is defined as the side of the second block body 22 as viewed from the first block body 21. However, the installation posture of the ultrasonic device 10 of the present embodiment is not particularly limited.

[0016] (Configuration of Ultrasonic Device 10) As shown in FIG. 1, the ultrasonic device 10 of the present embodiment includes a bolt-clamped Langevin transducer (hereinafter referred to as "BLT") 20 and an outer cylinder 30 that houses the BLT 20 therein. The ultrasonic device 10 of the present embodiment is used for health care products using ultrasonic waves. However, the use of the ultrasonic device 10 is not limited to health care products, and it may be an air ultrasonic sensor or air haptics. The outer cylinder 30 corresponds to the "distance defining portion" of the present disclosure.

[0017] (Configuration of BLT 20) The BLT 20 includes a first block body 21, a second block body 22, a piezoelectric unit 40, a bolt 50, and a tip member 60. The first block body 21, the second block body 22, and the piezoelectric unit 40 are arranged in this order from the rear side in the axial direction as the second block body 22, the piezoelectric unit 40, and the first block body 21. That is, the arrangement direction of the first block body 21, the second block body 22, and the piezoelectric unit 40 is the axial direction. The piezoelectric unit 40 corresponds to the "vibration generating portion" of the present disclosure.

[0018] The first block body 21 is a metal block body formed in a cylindrical shape with the central axis L as the axis. The first block body 21 is formed of, for example, aluminum, an aluminum alloy, titanium, a titanium alloy, stainless steel, iron, or the like. As shown in FIG. 2, a through hole 23 penetrating in the axial direction is formed in the first block body 21. The through hole 23 is formed in the central portion of the first block body 21 when viewed from the axial direction. Female threads for screwing the bolt 50 and the tip member 60 are formed on the inner wall surface of the through hole 23.

[0019] A flange 24 is formed at the rear end of the first block body 21. The flange 24 of the present embodiment is integrally formed on the outer peripheral surface of the first block body 21, but may be formed separately from the first block body 21. Further, the flange 24 of the present embodiment is formed over the entire circumference of the first block body 21, but may be connected to a part of the first block body 21. The flange 24 corresponds to the "leakage prevention member" of the present disclosure.

[0020] The second block body 22 is a metal block body formed in a cylindrical shape with the central axis L as the axis. The diameter of the second block body 22 is the same as the diameter of the first block body 21. However, the diameter of the second block body 22 may be different from the diameter of the first block body 21. The second block body 22 is formed of, for example, aluminum, an aluminum alloy, titanium, a titanium alloy, stainless steel, iron, or the like. The second block body 22 may be formed of the same material as the first block body 21 or may be formed of a material different from that of the first block body 21.

[0021] As shown in FIG. 2, a bottomed hole portion 25 extending in the axial direction is formed in the second block body 22. The hole portion 25 is formed at the center of the second block body 22 when viewed in the axial direction. The hole portion 25 is formed so as to be recessed from the front surface to the rear side of the second block body 22. A female thread for screwing the bolt 50 is formed on the inner wall surface of the hole portion 25. For example, the diameter of the hole portion 25 is the same as the diameter of the through hole 23 of the first block body 21. However, the diameter of the hole portion 25 may be different from the diameter of the through hole 23.

[0022] The piezoelectric unit 40 has a pair of power supply terminals 41A and 41B that are supplied with power from a power supply unit (not shown), and generates vibration by the power received by the power supply terminals 41A and 41B. The piezoelectric unit 40 includes, for example, a plurality of laminated disc-shaped piezoelectric ceramic elements. The piezoelectric unit 40 is formed in an annular shape centered on the central axis L. In the present embodiment, the outer diameter of the piezoelectric unit 40 is slightly smaller than the diameters of the first block body 21 and the second block body 22. However, the outer diameter of the piezoelectric unit 40 may be larger than or equal to the diameters of the first block body 21 and the second block body 22.

[0023] As shown in FIGS. 1 and 2, in the present embodiment, two piezoelectric units 40 are arranged adjacent to each other in the axial direction. However, the number of piezoelectric units 40 can be changed. That is, the ultrasonic device 10 may include a single piezoelectric unit 40.

[0024] These piezoelectric units 40 are arranged between the first block body 21 and the second block body 22 in the axial direction. The first block body 21 is located on the front side of the piezoelectric unit 40. Also, the second block body 22 is located on the rear side of the piezoelectric unit 40. These piezoelectric units 40 are sandwiched between the first block body 21 and the second block body 22.

[0025] The bolt 50 extends along the central axis L and is arranged so as to overlap with the central axis L. A male thread is formed on the outer peripheral surface of the bolt 50. As shown in FIG. 2, the bolt 50 penetrates through the annular piezoelectric unit 40.

[0026] The first block body 21 is fixed to the front end portion of the bolt 50, and the second block body 22 is fixed to the rear end portion of the bolt 50. The front end portion of the bolt 50 is inserted into the through hole 23 of the first block body 21. The male thread of the bolt 50 is screwed with the female thread formed on the inner wall surface of the through hole 23. Further, the rear end portion of the bolt 50 is inserted into the hole portion 25 of the second block body 22. The male thread of the bolt 50 is screwed with the female thread formed on the inner wall surface of the hole portion 25.

[0027] The first block body 21 and the second block body 22 are screwed to the bolt 50, and the piezoelectric unit 40 is sandwiched between the first block body 21 and the second block body 22, so that the first block body 21, the second block body 22, and the piezoelectric unit 40 are integrated.

[0028] The tip member 60 is a member attached to the first block body 21 from the front side. The tip member 60 is formed of, for example, aluminum, an aluminum alloy, titanium, a titanium alloy, stainless steel, iron, or the like. The tip member 60 may be formed of the same material as the first block body 21 and the second block body 22, or may be formed of a material different from that of the first block body 21 and the second block body 22. As shown in FIG. 2, for example, the tip member 60 has a base portion 61, a diaphragm 62, a connecting portion 63, and a shaft portion 64.

[0029] The base portion 61 directly or indirectly supports the diaphragm 62, the connecting portion 63, and the shaft portion 64. The base portion 61 is a disk-shaped portion formed substantially circular when viewed in the axial direction. The connecting portion 63 is connected to the front side of the base portion 61, and the shaft portion 64 is connected to the rear side of the base portion 61. In the present embodiment, the diameter of the base portion 61 is slightly larger than the diameter of the first block body 21. However, the diameter of the base portion 61 may be equal to or smaller than the diameter of the first block body 21.

[0030] The diaphragm 62 is located on the front side of the base portion 61 and is connected to the base portion 61 via the connecting portion 63. The diaphragm 62 is a disk-shaped portion formed in a circular shape when viewed from the axial direction. The diaphragm 62 vibrates when the vibration generated by the piezoelectric unit 40 is transmitted thereto. When the diaphragm 62 vibrates, ultrasonic wave US is radiated. The direction from the front end surface 62A of the diaphragm 62 toward the object TO is the front side, and the direction from the diaphragm 62 toward the flange 24 is the rear side. Most of the ultrasonic wave US is radiated forward from the front end surface 62A which is the front surface of the diaphragm 62, and a part of the ultrasonic wave US is also radiated rearward from the diaphragm 62.

[0031] In the present embodiment, the diameter of the diaphragm 62 is the same as the diameter of the first block body 21. However, the diameter of the diaphragm 62 may be different from the diameter of the first block body 21. That is, the diameter of the diaphragm 62 may be larger or smaller than the diameter of the first block body 21.

[0032] The connecting portion 63 is provided between the base portion 61 and the diaphragm 62 and supports the diaphragm 62. This connecting portion 63 has a groove portion 63A formed in an annular shape around the central axis L. The inner wall surface of the groove portion 63A is a smooth surface that connects the diaphragm 62 and the base portion 61. Here, the term "smooth" means that the whole is formed by a curved surface or a flat surface and no bent portion is provided.

[0033] As described above, the groove portion 63A is formed in an annular shape around the central axis L. The cross-sectional shape by a plane including the central axis L is a semi-elliptical shape that is recessed from the outer side in the radial direction toward the inner side as shown in FIG. 2. The minor axis of this semi-elliptical shape is parallel to the central axis L. Also, the major axis of this semi-elliptical shape is parallel to the radial direction.

[0034] However, the cross-sectional shape of the groove portion 63A may be a semi-elliptical shape with the minor axis parallel to the radial direction and the major axis parallel to the central axis L. Further, the cross-sectional shape of the groove portion 63A may be a semi-circular shape or a horseshoe shape. Further, the cross-sectional shape of the groove portion 63A may be any shape as long as it is a surface without a curved surface as a whole or a bent portion combining a curved surface and a flat surface as a whole.

[0035] The shaft portion 64 is connected to the center of the base portion 61 as viewed from the axial direction and protrudes rearward from the base portion 61. The shaft portion 64 is formed in a cylindrical shape. A male screw that is screwed into the female screw of the through hole 23 of the first block body 21 is formed on the outer peripheral surface of the shaft portion 64. The tip member 60 is fixed to the first block body 21 by screwing the shaft portion 64 into the through hole 23 until the rear surface of the base portion 61 abuts against the front surface of the first block body 21.

[0036] (Configuration of the outer cylinder 30) The outer cylinder 30 is formed in a cylindrical shape with the central axis L as the axis. The outer cylinder 30 is formed of, for example, aluminum, an aluminum alloy, titanium, a titanium alloy, stainless steel, iron, or the like. BLT20 is accommodated inside the outer cylinder 30. The rear end of the outer cylinder 30 coincides with the rear end of BLT20 in the axial direction. The front end 30A of the outer cylinder 30 is located forward of the front end of BLT20 in the axial direction. The inner diameter D1 of the outer cylinder 30 is the same as the diameter of the flange 24 of the first block body 21. The inner diameter D1 of the outer cylinder 30 is constant at any position in the axial direction. For example, BLT20 may be fixed to the outer cylinder 30 by welding the outer edge of the flange 24 to the inner wall surface of the outer cylinder 30.

[0037] In the present embodiment, since the first block body 21 and the outer cylinder 30 are formed of the above metals, the acoustic impedance is much larger than that of air, and the sound pressure reflectivity of the flange 24 of the first block body 21 and the outer cylinder 30 is 1.

[0038] (Explanation of the operation of the ultrasonic device 10) In such an ultrasonic device 10 of the present embodiment, when power is supplied from an external power supply unit to the piezoelectric unit 40, the piezoelectric unit 40 vibrates. By setting the driving frequency of the piezoelectric unit 40 to the resonance frequency of the ultrasonic device 10, the ultrasonic device 10 resonates with the vibration of the piezoelectric unit 40. As a result, the diaphragm 62 vibrates strongly, generating ultrasonic waves US with a high sound pressure. Most of the generated ultrasonic waves US are radiated forward from the front end surface 62A, and a part of the ultrasonic waves US is also radiated rearward from the diaphragm 62. In this way, the ultrasonic device 10 radiates the ultrasonic waves US generated by the diaphragm 62 into the air. Further, a standing wave is generated in the space in front of the diaphragm 62 by being reflected by the object TO. The diaphragm 62 is disposed at the position of the antinode of the longitudinal vibration when the ultrasonic device 10 resonates. As a result, the amplitude of the diaphragm 62 can be increased, and ultrasonic waves US with a higher sound pressure can be output.

[0039] The dimension L1 from the front end surface 62A of the diaphragm 62 to the front end 30A of the outer cylinder 30 is set to be 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration. Therefore, when the front end 30A of the outer cylinder 30 is directed at the object TO, the dimension from the front end surface 62A of the diaphragm 62 to the object TO is 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration.

[0040] The dimension L1 of the present embodiment is twice the half wavelength HW of the vibration, but may be one time the half wavelength HW or an integral multiple of 3 or more. By doing so, the amplitude becomes maximum at the position of the object TO, so that ultrasonic waves US with a higher sound pressure can be applied to the object TO. Further, the ultrasonic waves US radiated rearward from the diaphragm 62 are reflected by the flange 24 and directed forward, so that leakage of the ultrasonic waves US can be prevented and the ultrasonic application to the object TO can be increased.

[0041] (Operational effects of Embodiment 1) (1) The ultrasonic device 10 of the present disclosure is an ultrasonic device 10 that emits ultrasonic waves US to the object TO, and includes a piezoelectric unit 40 that generates vibrations according to the ultrasonic waves US, and a diaphragm 62 having a front end surface 62A to which the vibrations are transmitted and that emits ultrasonic waves US toward the object TO. The dimension from the front end surface 62A of the diaphragm 62 to the object TO is 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration. This is the ultrasonic device 10.

[0042] Since the dimension from the front end surface 62A of the diaphragm 62 to the object TO is 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration generated by the piezoelectric unit 40, the ultrasonic waves US are applied to the object at the point where the amplitude becomes large. Therefore, it is possible to suppress an increase in power consumption while applying sufficient ultrasonic energy to the object TO.

[0043] (2) It further includes an outer cylinder 30 having a cylindrical shape and accommodating at least the diaphragm 62 therein. The dimension L1 from the front end surface 62A of the diaphragm 62 to the front end of the outer cylinder 30 is preferably 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration. When the front end of the outer cylinder 30 is directed at the object TO, the dimension from the front end surface 62A of the diaphragm 62 to the object TO becomes 0.8 times or more and 1.2 times or less of an integral multiple of the half wavelength HW of the vibration generated by the piezoelectric unit 40, so that the handling of the ultrasonic device 10 becomes easy.

[0044] (3) The acoustic impedance of the outer cylinder 30 is preferably greater than the acoustic impedance of air. Since the ultrasonic waves US are likely to be reflected by the inner wall of the outer cylinder 30, the ultrasonic energy applied to the object TO can be increased.

[0045] (4) When the direction from the front end surface 62A of the diaphragm 62 toward the object TO is defined as the front side, it is preferable to further include a flange 24 that prevents leakage of the ultrasonic waves US radiated from the diaphragm 62 to the rear side. The flange 24 can prevent the ultrasonic waves US radiated from the diaphragm 62 to the rear side from leaking.

[0046] (Embodiment 2) Embodiment 2 will be described with reference to FIG. 3. The ultrasonic device 110 of Embodiment 2 has a modified shape of the outer cylinder 30 of Embodiment 1, and other configurations are the same as those of the ultrasonic device 10 of Embodiment 1. The same reference numerals as those in Embodiment 1 will be used for the same configurations as in Embodiment 1.

[0047] The ultrasonic device 110 includes a BLT 20 and an outer cylinder 130 that houses the BLT 20 therein. As shown in FIG. 3, the outer cylinder 130 of the present embodiment includes a cylindrical portion 131 extending in a cylindrical shape and a tip portion 132 formed at the tip of the cylindrical portion 131. The cylindrical portion 131 has the same shape as the outer cylinder 30 of Embodiment 1 and is shorter than the outer cylinder 30 of Embodiment 1 by the length of the tip portion 132 in the axial direction. Therefore, the dimension L2 from the front end surface 62A of the diaphragm 62 to the front end 132A of the tip portion 132 is twice the half wavelength HW of the same vibration as in Embodiment 1.

[0048] The tip portion 132 is formed in a frustum shape with the central axis L as the axis. The front end 132A and the rear end 132B of the tip portion 132 are open in the axial direction. The inner diameter D2 of the tip portion 132 decreases from the rear end 132B toward the front end 132A. The inner diameter D2 at the rear end 132B of the tip portion 132 is the same as the inner diameter D1 of the cylindrical portion 131.

[0049] According to the present embodiment, since a part of the ultrasonic wave US radiated from the front end surface 62A of the diaphragm 62 is reflected by the inner wall surface of the tip portion 132 and heads toward the front end 132A, sufficient ultrasonic energy can be applied to the object TO, and the ultrasonic wave US can be applied to the object TO pinpointedly.

[0050] (Other Embodiments) The above embodiments can be implemented with the following modifications. The above embodiments and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0051] ·In the first and second embodiments described above, the connecting portion 63 was exemplified as the support column for fixing the diaphragm 62, but it may be a round bar-shaped support column extending in the axial direction. In that case, the diaphragm fixed to the tip of the support column may be a flat disc-shaped diaphragm.

[0052] ·In the first and second embodiments described above, the flange 24, which is a reflector that reflects the ultrasonic wave US, was exemplified as the leakage prevention member, but it may be a leakage prevention member composed of a member that absorbs the ultrasonic wave US (for example, a sponge-like member).

[0053] ·In the first and second embodiments described above, those in which the dimensions L1, L2, and L3 are smaller than the inner diameter D1 were exemplified, but the dimensions L1, L2, and L3 may be the same as the inner diameter D1, or may be larger than the inner diameter D1.

Explanation of Reference Numerals

[0054] 10, 110: Ultrasonic device 20: Bolt-tightened Langevin-type vibrator 21: First block body 22: Second block body 23: Through hole 24: Flange (leakage prevention member) 25: Hole portion 30, 130: Outer cylinder (distance regulating portion) 30A: Tip 40: Piezoelectric unit (vibration generating portion) 41A, 41B: Power supply terminals 50: Bolt 60: Tip member 61: Base portion 62: Diaphragm 62A: Tip surface 63: Connecting portion 63A: Groove portion 64: Shaft portion 70: Cover 70A: Front end 131: Cylindrical portion 132: Tip portion 132A: Front end 132B: Rear end D1, D2: Inner diameter L: Central axis L1, L2, L3: Dimensions TO: Object US: Ultrasonic wave

Claims

1. An ultrasonic device that emits ultrasonic waves to an object, comprising: a vibration generating unit that generates vibrations corresponding to the ultrasonic waves; a diaphragm having a tip surface that radiates the ultrasonic waves toward the object when the vibration is transmitted thereto; a distance defining unit that contacts the object and defines a distance between the tip surface of the diaphragm and the object, wherein the distance is 0.8n times or more and 1.2n times or less of a half wavelength of the vibration (n is a natural number). The ultrasonic device.

2. The ultrasonic device according to claim 1, wherein the distance defining unit has a cylindrical shape, at least the diaphragm is housed therein, and has a tip on the side opposite to the vibration generating unit with respect to the diaphragm.

3. The ultrasonic device according to claim 2, wherein an acoustic impedance of the distance defining unit is greater than an acoustic impedance of air.

4. The ultrasonic device according to claim 1 or claim 2, further comprising a leakage prevention member that prevents leakage of ultrasonic waves radiated to the rear side from the diaphragm when the direction from the tip surface of the diaphragm toward the object is defined as the front side.

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