CN117941377A - Ultrasonic transducer - Google Patents

Abstract

The main vibration part (110 m) which is a part of the exterior part (110) located inside the cylinder (120) resonates with a phase opposite to that of the ultrasonic vibrator (130), as viewed from the 1 st direction (Z-axis direction). The secondary vibration section (110 s), which is a section of the outer cover section (110) located outside the cylinder (120) and inside the restraining section (140), resonates in the 2 nd direction (X-axis direction) when viewed from the 1 st direction (Z-axis direction), within a range in which the absolute value of the phase difference of the resonant vibration with respect to the primary vibration section (110 m) is 120 DEG to 180 deg.

Description

Ultrasonic transducer

Technical Field

The present invention relates to ultrasonic transducers.

Background

As a prior document disclosing the structure of an ultrasonic sensor, japanese patent application laid-open No. 2007-142967 (patent document 1) is known. The ultrasonic sensor described in patent document 1 is mounted on the inner surface side of a bumper or a resin portion for a vehicle. The ultrasonic sensor has an ultrasonic transducer and a housing. The ultrasonic vibrator transmits and receives ultrasonic waves. The housing accommodates the ultrasonic vibrator. The ultrasonic vibrator is fixed to the inner surface of the bottom surface portion of the case while the outer surface of the bottom surface portion is in contact with the inner surface of the vehicle bumper or the resin portion.

An ultrasonic wave transmitting portion is formed in a part of the bottom surface of the case. The ultrasonic wave transmitting portion is disposed in contact with the vehicle bumper or the resin portion and the ultrasonic vibrator. The ultrasonic wave transmitting portion is made of a material different from that of the case, and has an acoustic impedance intermediate between that of the ultrasonic vibrator and that of the vehicle bumper or the resin portion. The ultrasonic sensor transmits and receives ultrasonic waves through the ultrasonic transmission unit and the vehicle bumper or the resin portion.

Prior art literature

Patent literature

Patent document 1, japanese patent laid-open No. 2007-142967

Disclosure of Invention

Problems to be solved by the invention

When the vibration region is limited to a narrow range in order to suppress the narrowing of the angular range of directivity, the transmission intensity and the reception sensitivity of the ultrasonic wave become low.

The present invention has been made in view of the above-described problems, and an object thereof is to provide an ultrasonic transducer capable of suppressing narrowing of the angular range of directivity while achieving at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

Technical scheme for solving problems

An ultrasonic transducer according to the present invention includes an exterior part, a cylindrical body, an ultrasonic transducer, and a restraint part. The outer housing portion has an inner surface. The cylinder is mounted on the inner surface. The ultrasonic vibrator is mounted on the cylinder body and is opposed to the inner surface with a space therebetween. The restraining part is mounted on the inner surface and is spaced from the cylinder to clamp the cylinder. The main vibration portion, which is a portion of the exterior part located inside the cylinder, resonates in a phase opposite to that of the ultrasonic vibrator, as viewed from the 1 st direction perpendicular to the inner surface. The secondary vibration portion, which is a portion of the outer casing portion located outside the cylinder and inside the constraining portion in the 2 nd direction orthogonal to the 1 st direction, resonates in a range of 120 ° to 180 ° in absolute value of a phase difference of the resonant vibration with respect to the primary vibration portion, as viewed from the 1 st direction.

Effects of the invention

According to the present invention, it is possible to suppress narrowing of the angular range of directivity while achieving at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

Drawings

Fig. 1 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 1 of the present invention.

Fig. 2 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 1 of the present invention.

Fig. 3 is a cross-sectional view showing a structure of an ultrasonic transducer included in an ultrasonic transducer according to embodiment 1 of the present invention.

Fig. 4 is a perspective view showing a displacement state in which a simulation analysis is performed by using a finite element method when an ultrasonic transducer according to embodiment 1 of the present invention transmits or receives ultrasonic waves.

Fig. 5 is a cross-sectional view of the ultrasonic transducer of fig. 4, as viewed from the direction of the V-V line arrow.

Fig. 6 is a diagram for explaining a relationship between the area of the vibration portion and the directivity.

Fig. 7 is a schematic diagram showing a state in which secondary sound sources vibrating in phases opposite to those of a primary sound source are arranged on both sides of the primary sound source.

Fig. 8 is a graph showing directivity subjected to simulation analysis using the finite element method when only the primary sound source is driven, when the sound pressure ratio of the primary sound source to the secondary sound source is set to 16:1, and when the sound pressure ratio of the primary sound source to the secondary sound source is set to 4:1.

Fig. 9 is a graph showing the sound pressure ratio of the sub-sound source to the main sound source and the transition of the sound pressure level when the radiation angle is 20 ° when the phase difference between the sine wave of the ultrasonic wave radiated from the main sound source and the sine wave of the ultrasonic wave radiated from the sub-sound source is changed.

Fig. 10 is a graph showing the sound pressure ratio of the sub-sound source to the main sound source and the transition of the sound pressure level when the radiation angle is 40 ° when the phase difference between the sine wave of the ultrasonic wave radiated from the main sound source and the sine wave of the ultrasonic wave radiated from the sub-sound source is changed.

Fig. 11 is a cross-sectional view showing a resonance mode of a main vibration unit that has been subjected to simulation analysis by using a finite element method in an ultrasonic transducer according to embodiment 1 of the present invention.

Fig. 12 is a cross-sectional view showing a resonance mode of a sub-vibration unit that has been subjected to simulation analysis by using a finite element method in the ultrasonic transducer according to embodiment 1 of the present invention.

Fig. 13 is a cross-sectional view showing a state in which resonance vibrations of the main vibration portion and resonance vibrations of the sub vibration portion, which have been subjected to simulation analysis using the finite element method, are in the same phase.

Fig. 14 is a graph showing the relationship between the ratio of the difference between the resonance frequency of the main vibrating portion and the resonance frequency of the sub vibrating portion to the resonance frequency of the main vibrating portion and the phase difference between the resonance vibrations of the main vibrating portion and the sub vibrating portion.

Fig. 15 is a graph showing the relationship between the ratio of the difference between the resonance frequency of the main vibrating portion and the resonance frequency of the sub vibrating portion to the resonance frequency of the main vibrating portion and the ratio of the resonance amplitude of the sub vibrating portion to the resonance amplitude of the main vibrating portion.

Fig. 16 is a plan view showing a restraining portion according to modification 1.

Fig. 17 is a plan view showing a restraining portion according to modification 2.

Fig. 18 is a plan view showing a restraining portion according to modification 3.

Fig. 19 is a plan view showing a restriction portion according to modification 4.

Fig. 20 is a plan view showing a restriction portion according to modification 5.

Fig. 21 is a plan view showing a restraining portion according to modification 6.

Fig. 22 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 7.

Fig. 23 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 8.

Fig. 24 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 9.

Fig. 25 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to modification 10 of embodiment 1 of the present invention.

Fig. 26 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 2 of the present invention.

Fig. 27 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 2 of the present invention.

Fig. 28 is a longitudinal sectional view showing the periphery of an ultrasonic transducer of the ultrasonic transducer according to modification 1 of embodiment 2 of the present invention.

Fig. 29 is a perspective view showing a cylindrical body and a metal plate portion of an ultrasonic transducer according to modification 2 of embodiment 2 of the present invention.

Fig. 30 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 3 of the present invention.

Fig. 31 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 3 of the present invention.

Fig. 32 is a perspective view showing a metal plate portion and a cylindrical body according to a comparative example.

Fig. 33 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 1.

Fig. 34 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 2.

Fig. 35 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 3.

Fig. 36 is a graph showing the relationship between the resonant frequency of each of the main vibration portion and the sub vibration portion and the length of the slit.

Fig. 37 is a perspective view showing a cylindrical body and a metal plate portion of an ultrasonic transducer according to a modification of embodiment 3 of the present invention.

Detailed Description

Hereinafter, an ultrasonic transducer according to each embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)

Fig. 1 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 1 of the present invention. Fig. 2 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 1 of the present invention. As shown in fig. 1 and 2, an ultrasonic transducer 100 according to embodiment 1 of the present invention includes an exterior part 110, a tubular body 120, an ultrasonic transducer 130, and a constraining part 140.

The exterior part 110 is a part of an exterior such as a vehicle bumper, a case of a personal computer or a smart phone, furniture, or a wall of a house. The outer housing 110 has an inner surface 111. The outer cover 110 has a substantially flat plate shape. The exterior part 110 is formed of a resin such as polypropylene. The thickness of the outer covering portion 110 is, for example, about 1.5 mm.

In the figure, the 1 st direction orthogonal to the inner surface 111 of the exterior part 110 is shown as the Z-axis direction, the 2 nd direction orthogonal to the 1 st direction is shown as the X-axis direction, and the 3 rd direction orthogonal to each of the 1 st and 2 nd directions is shown as the Y-axis direction.

The cylinder 120 is mounted on the inner surface 111 of the outer part 110. In the present embodiment, one end of the cylinder 120 in the 1 st direction (Z-axis direction) is bonded to the inner surface 111 of the exterior part 110. The cylinder 120 has a rectangular annular shape. The cylinder 120 has a long side direction along the 3 rd direction (Y-axis direction) and has a short side direction along the 2 nd direction (X-axis direction). The axial direction of the cylinder 120 is along the 1 st direction (Z-axis direction).

The cylinder 120 is formed of resin, glass epoxy, metal, or the like. From the viewpoint of suppressing characteristic changes caused by temperature changes of the ultrasonic transducer 100, the cylinder 120 is preferably formed of metal. On the other hand, from the standpoint of reducing the frequency of the ultrasonic waves transmitted or received by the ultrasonic transducer 100 and from the standpoint of miniaturizing the ultrasonic transducer 100, the cylinder 120 is preferably formed of resin. In the present embodiment, the cylinder 120 is formed of glass epoxy having intermediate characteristics of metal and resin.

Fig. 3 is a cross-sectional view showing a structure of an ultrasonic transducer included in an ultrasonic transducer according to embodiment 1 of the present invention. As shown in fig. 1, the ultrasonic transducer 130 is attached to the tubular body 120 and faces the inner surface 111 of the outer housing 110 with a gap therebetween. Specifically, the ultrasonic transducer 130 is attached to the other end of the cylindrical body 120 in the 1 st direction (Z-axis direction), and faces the inner surface 111 of the exterior part 110 through the inner space of the cylindrical body 120.

As shown in fig. 1 to 3, the ultrasonic transducer 130 is a piezoelectric element including a piezoelectric body 131. As shown in fig. 3, in the present embodiment, the ultrasonic vibrator 130 includes 2 piezoelectric bodies 131 stacked. The polarization directions Dp of the 2 piezoelectric bodies 131 are different from each other. Specifically, the polarization directions Dp of the 2 piezoelectric bodies 131 are opposite to each other in the 1 st direction (Z-axis direction). The 2 piezoelectric bodies 131 are sandwiched between the 1 st electrode 132 and the 2 nd electrode 133, and the intermediate electrode 134 is arranged between the 2 piezoelectric bodies 131. The 1 st electrode 132 and the 2 nd electrode 133 are electrically connected to a processing circuit 150 capable of applying an ac voltage. The ultrasonic vibrator 130 is a so-called tandem bimorph piezoelectric vibrator. The total thickness of the 2 piezoelectric bodies 131 is, for example, 0.5mm to 0.75 mm.

The restraining portion 140 is attached to the inner surface 111 of the outer housing 110, and sandwiches the cylinder 120 with a space therebetween. In the present embodiment, the restraining portion 140 has an annular shape. Specifically, the constraint part 140 has a rectangular annular shape. The restraining portion 140 is spaced apart from the cylinder 120 and surrounds the cylinder 120 from the outside. However, the constraining section 140 may sandwich the cylindrical body 120 with a gap from the cylindrical body 120 in the 2 nd direction (X-axis direction). One end of the restraint portion 140 in the 1 st direction (Z-axis direction) is bonded to the inner surface 111 of the outer case 110.

The restraint portion 140 is formed of a metal such as stainless steel or aluminum, or a material having high rigidity such as glass epoxy. The portion of the exterior part 110 to which the constraining section 140 is attached is constrained, so that vibration of a sub-vibration section, which will be described later, can be enclosed in the sub-vibration section and stabilized.

Fig. 4 is a perspective view showing a displacement state in which a simulation analysis is performed by using a finite element method when an ultrasonic transducer according to embodiment 1 of the present invention transmits or receives ultrasonic waves. Fig. 5 is a cross-sectional view of the ultrasonic transducer of fig. 4, as viewed from the direction of the V-V line arrow. As simulation analysis conditions, the thickness of the exterior part 110 was 1.5mm, the thickness of the piezoelectric body 131 was 0.6mm, the long side dimension of the outer shape of the cylinder 120 was 16mm, the short side dimension was 6mm, the thickness was 0.4mm, and the width of the cylinder 120 was 0.5mm. That is, the long side dimension of the inner shape of the cylinder 120 is 15mm, and the short side dimension is 5mm. The width of the restriction portion 140 was set to 2mm, and the thickness was set to 3mm. The interval between the cylindrical body 120 and the restriction portion 140 in the 2 nd direction (X-axis direction) was set to 4mm.

As shown in fig. 4 and 5, the ultrasonic transducer 100 according to embodiment 1 of the present invention includes a main vibrating portion 110m, which is a portion of the exterior portion 110 located inside the cylinder 120, and a sub vibrating portion 110s, which is a portion of the exterior portion 110 located outside the cylinder 120 and inside the constraining portion 140, in the 2 nd direction (X-axis direction), as viewed from the 1 st direction (Z-axis direction).

As shown in fig. 5, the main vibration portion 110m resonates with a phase opposite to that of the ultrasonic vibrator 130. That is, the displacement direction of the resonance vibration Bm of the main vibration portion 110m and the displacement direction of the resonance vibration Bp of the ultrasonic vibrator 130 are opposite to each other in the 1 st direction (Z-axis direction).

The sub-vibration portion 110s resonates in a range in which the absolute value of the phase difference of the resonant vibration with respect to the main vibration portion 110m is 120 ° or more and 180 ° or less. That is, the displacement direction of the resonance vibration Bs of the sub-vibration portion 110s and the displacement direction of the resonance vibration Bm of the main vibration portion 110m are opposite to each other in the 1 st direction (Z-axis direction).

Here, a mechanism that can achieve the effect of the ultrasonic transducer 100 according to embodiment 1 of the present invention will be described.

As shown in fig. 5, the main vibration portion 110m resonates in a phase opposite to that of the ultrasonic vibrator 130, whereby vibration leakage to the periphery of the main vibration portion 110m in the exterior portion 110 can be reduced as shown in fig. 4. This suppresses the narrowing of the angular range of directivity of the ultrasonic transducer 100. In the ultrasonic transducer 100, the above-described resonant vibration Bs is excited in the sub-vibration portion 110s, whereby it is possible to suppress narrowing of the angular range of the directivity of the ultrasonic transducer 100 while achieving at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

First, a mechanism of suppressing the narrowing of the angular range of directivity by the main vibration and the sub-vibration will be described using a simplified model.

Fig. 6 is a diagram for explaining a relationship between the area of the vibration portion and the directivity. As shown in fig. 6, when it is assumed that ultrasonic waves radiated from the vibration site are radiated from a plurality of point sound sources S arranged at intervals from each other, a difference DL in path length between ultrasonic waves radiated from the point sound sources S located at one end and the other end of the vibration site in a direction other than the radiation angle θ of 0 ° increases as the area of the vibration site increases. Since the interference occurs due to the relationship between the difference DL between the path lengths and the wavelength of the ultrasonic wave, basically, the larger the area of the vibration portion and the higher the frequency of the ultrasonic wave become, the narrower the angle range of the directivity becomes.

On the other hand, if the area of the vibration portion is reduced, the directivity can be suppressed from narrowing in the angular range, but the sound pressure of the ultrasonic wave to be radiated becomes low. Here, the results of simulation analysis of the relationship between sound pressure and directivity in the case where secondary sound sources vibrating in phases opposite to those of the primary sound source are arranged on both sides of the primary sound source will be described using the finite element method.

Fig. 7 is a schematic diagram showing a state in which secondary sound sources vibrating in phases opposite to those of a primary sound source are arranged on both sides of the primary sound source. As shown in fig. 7, simulation analysis was performed using a simplified model in which a secondary sound source SS vibrating in a phase opposite to that of the primary sound source MS was arranged on both sides of the primary sound source MS.

Fig. 8 is a graph showing directivity subjected to simulation analysis using the finite element method when only the primary sound source is driven, when the sound pressure ratio of the primary sound source to the secondary sound source is set to 16:1, and when the sound pressure ratio of the primary sound source to the secondary sound source is set to 4:1. In fig. 8, the sound pressure level (dB) is shown on the vertical axis, and the radiation angle (°) from the center of the primary sound source is shown on the circumferential axis. Further, the directivity when driving only the primary sound source is shown by a solid line, the directivity when the sound pressure ratio of the primary sound source and the secondary sound source is set to 16:1 is shown by a broken line, and the directivity when the sound pressure ratio of the primary sound source and the secondary sound source is set to 4:1 is shown by a two-dot chain line. In each of the above 3 cases, the sound pressure level in the front direction of the radiation angle θ=0° was set to 0dB, and the transition of the radiation angle θ and the sound pressure level was shown.

As shown in fig. 8, the angular range of directivity is widened when the sound pressure ratio of the primary sound source MS and the secondary sound source SS is set to 16:1, and the angular range of directivity is further widened when the sound pressure ratio of the primary sound source MS and the secondary sound source SS is set to 4:1.

When the sound pressure ratio of the primary sound source MS and the secondary sound source SS is set to 4: when 1, the sound pressure level in the front direction of the radiation angle θ=0° becomes lower due to interference of the ultrasonic wave radiated from the primary sound source MS and the ultrasonic wave radiated from the secondary sound source SS, but the sound pressure level becomes highest in the range of the radiation angle θ of 20 ° or more and 40 ° or less.

The change in sound pressure level caused by the disturbance varies according to the sound pressure ratio of the primary sound source MS and the secondary sound source SS, and the phase difference of the sine wave of the ultrasonic wave radiated from the primary sound source MS and the sine wave of the ultrasonic wave radiated from the secondary sound source SS.

Fig. 9 is a graph showing the sound pressure ratio of the sub-sound source to the main sound source and the transition of the sound pressure level when the radiation angle is 20 ° when the phase difference between the sine wave of the ultrasonic wave radiated from the main sound source and the sine wave of the ultrasonic wave radiated from the sub-sound source is changed. Fig. 10 is a graph showing the sound pressure ratio of the sub-sound source to the main sound source and the transition of the sound pressure level when the radiation angle is 40 ° when the phase difference between the sine wave of the ultrasonic wave radiated from the main sound source and the sine wave of the ultrasonic wave radiated from the sub-sound source is changed.

In fig. 9, the sound pressure level (dB) at a radiation angle of 20 ° is shown on the vertical axis, and the sound pressure ratio (%) of the secondary sound source to the primary sound source is shown on the horizontal axis. In fig. 10, the sound pressure level (dB) at a radiation angle of 40 ° is shown on the vertical axis, and the sound pressure ratio (%) of the secondary sound source to the primary sound source is shown on the horizontal axis. In fig. 9 and 10, the sound pressure level in the front direction at the radiation angle θ=0° is set to 0dB, and the transition when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source and the sine wave of the ultrasonic wave radiated from the secondary sound source is 90 ° is shown by L1, the transition when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source and the sine wave of the ultrasonic wave radiated from the secondary sound source is 120 ° is shown by L2, and the transition when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source and the sine wave of the ultrasonic wave radiated from the secondary sound source is 150 ° is shown by L3, and the transition when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source and the sine wave radiated from the secondary sound source is 180 °.

In each of fig. 9 and 10, when the sound pressure level is increased, the angular range of directivity is increased as compared with the case where the sound pressure ratio of the sub-sound source SS to the main sound source MS is 0%.

As shown in fig. 9 and 10, when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source MS and the sine wave of the ultrasonic wave radiated from the secondary sound source SS is 90 °, the sound pressure level at the radiation angle of 20 ° and 40 ° does not become larger than when the sound pressure ratio of the secondary sound source SS to the primary sound source MS is 0%.

When the absolute value of the phase difference is 120 °, the sound pressure level at the radiation angle of 20 ° is substantially the same as that at the sound pressure ratio of the sub-sound source SS to the main sound source MS of 0%, and the sound pressure level at the radiation angle of 40 ° is greater than that at the sound pressure ratio of the sub-sound source SS to the main sound source MS of 0%.

When the absolute value of the phase difference is 150 ° and 180 °, the sound pressure level at the radiation angle of 20 ° and 40 ° becomes larger than when the sound pressure ratio of the sub-sound source SS to the main sound source MS is 0%.

From the above results, it was confirmed that the angular range of directivity was widened in the range where the absolute value of the phase difference of the sine wave of the ultrasonic wave radiated from the primary sound source MS and the sine wave of the ultrasonic wave radiated from the secondary sound source SS was 120 ° or more and 180 ° or less. For example, when the absolute value of the phase difference between the sine wave of the ultrasonic wave radiated from the primary sound source MS and the sine wave of the ultrasonic wave radiated from the secondary sound source SS is 180 ° and the sound pressure ratio of the secondary sound source SS to the primary sound source MS is 10% or more, the sound pressure level becomes higher by 2dB or more when the radiation angle is 20 ° and the sound pressure level becomes higher by 6dB or more when the radiation angle is 40 ° than when the sound pressure ratio of the secondary sound source SS to the primary sound source MS is 0%.

Next, the vibration modes in the main vibration portion 110m and the sub vibration portion 110s will be described. Fig. 11 is a cross-sectional view showing a resonance mode of a main vibration unit that has been subjected to simulation analysis by using a finite element method in an ultrasonic transducer according to embodiment 1 of the present invention. Fig. 12 is a cross-sectional view showing a resonance mode of a sub-vibration unit that has been subjected to simulation analysis by using a finite element method in the ultrasonic transducer according to embodiment 1 of the present invention. In fig. 11 and 12, the same cross-sectional position as in fig. 5 is shown in cross-section.

The ultrasonic transducer 100 according to embodiment 1 of the present invention transmits and receives ultrasonic waves in accordance with the resonance mode of the main vibration unit 110m shown in fig. 11. The ultrasonic transducer 100 according to embodiment 1 of the present invention suppresses the narrowing of the angular range of directivity by overlapping the resonance mode of the sub-vibration portion 110s and the resonance mode of the main vibration portion 110m shown in fig. 12. In order to efficiently perform at least one of transmission and reception of ultrasonic waves, the sub-vibration unit 110s is resonantly vibrated at a frequency in the vicinity of the resonance frequency of the main vibration unit 110 m.

Fig. 13 is a cross-sectional view showing a state in which resonance vibrations of the main vibration portion and resonance vibrations of the sub vibration portion, which have been subjected to simulation analysis using the finite element method, are in the same phase. In fig. 13, a cross section is taken at the same cross section position as in fig. 5. When the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s is out of the proper range, the resonance vibration Bm of the main vibration portion 110m and the resonance vibration Bs of the sub vibration portion 110s have the same phase as shown in fig. 13. In this case, the sound pressure level in the front direction of the radiation angle θ=0° becomes high due to interference of the ultrasonic wave radiated from the main vibration portion 110m and the ultrasonic wave radiated from the sub vibration portion 110s, and the angular range of the directivity becomes narrow.

On the other hand, when the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s is within a proper range, the phase difference and the amplitude ratio between the resonance vibration Bm of the main vibration portion 110m and the resonance vibration Bs of the sub vibration portion 110s can be set to a desired state as shown in fig. 5.

First, in order to vibrate the main vibration portion 110m in a resonance mode with little vibration leakage, it is required to perform resonance vibration of the main vibration portion 110m and the ultrasonic vibrator 130 in opposite phases while maintaining physical balance of the main vibration portion 110m and the ultrasonic vibrator 130.

In order to maintain the physical balance between the main vibrating portion 110m and the ultrasonic transducer 130, if the sound velocity of the transverse wave of the outer cover 110 is Cb, the sound velocity of the transverse wave of the piezoelectric body 131 is Cp, the thickness of the main vibrating portion 110m is Tb, and the thickness of the piezoelectric body 131 is Tp, the relationship of 0.7 CpTp/cb+.tb+.1.3 CpTp/Cb is preferably satisfied. The sound velocity Cb of the transverse wave of the exterior part 110 is determined by the material constituting the exterior part 110. The sound velocity Cp of the transverse wave of the piezoelectric body 131 is determined by the material constituting the piezoelectric body 131. When a plurality of piezoelectric elements 131 are laminated in the ultrasonic vibrator 130, the thickness Tp of the piezoelectric elements 131 is a total value of the thicknesses of the piezoelectric elements 131.

By satisfying the relationship of 0.7 CpTp/Cb.ltoreq.Tb.ltoreq.1.3 CpTp/Cb, physical balance between the main vibrating portion 110m and the ultrasonic vibrator 130 during vibration can be maintained, and reduction in the amplitude of resonance vibration of the main vibrating portion 110m and vibration leakage can be suppressed. In addition, it is further preferable to satisfy the relationship of tb= CpTp/Cb.

Next, the results of simulation analysis of the relationship between the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s and the phase difference between the resonance vibration Bm of the main vibration portion 110m and the resonance vibration Bs of the sub vibration portion 110s by using the finite element method will be described. Fig. 14 is a graph showing the relationship between the ratio of the difference between the resonance frequency of the main vibrating portion and the resonance frequency of the sub vibrating portion to the resonance frequency of the main vibrating portion and the phase difference between the resonance vibrations of the main vibrating portion and the sub vibrating portion. In fig. 14, the vertical axis shows the phase difference (°) between the resonance vibration of the main vibration unit and the resonance vibration of the sub vibration unit, and the horizontal axis shows the ratio (%) of the difference between the resonance frequency of the main vibration unit and the resonance frequency of the sub vibration unit to the resonance frequency of the main vibration unit.

Further, as the interval between the cylindrical body 120 and the constraining section 140 in the 2 nd direction (X-axis direction) increases, the resonance frequency of the secondary vibrating section decreases, and as the interval decreases, the resonance frequency of the secondary vibrating section increases.

As shown in fig. 14, when the resonance frequency of the sub-vibration portion 110s is lower than the resonance frequency of the main vibration portion 110m, the phase difference between the resonance vibration of the main vibration portion 110m and the resonance vibration of the sub-vibration portion 110s is 0 ° or more and 80 ° or less. When the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s to the resonance frequency of the main vibration portion 110m is 7%, as indicated by a broken line La, the phase difference between the resonance vibration of the main vibration portion 110m and the resonance vibration of the sub vibration portion 110s becomes 120 °.

Next, the results of simulation analysis will be described with respect to the relationship between the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s and the ratio of the resonance amplitude of the sub vibration portion 110s to the resonance amplitude of the main vibration portion 110m using the finite element method. Fig. 15 is a graph showing the relationship between the ratio of the difference between the resonance frequency of the main vibrating portion and the resonance frequency of the sub vibrating portion to the resonance frequency of the main vibrating portion and the ratio of the resonance amplitude of the sub vibrating portion to the resonance amplitude of the main vibrating portion. In fig. 15, a ratio (%) of the resonance amplitude of the sub-vibration portion to the resonance amplitude of the main vibration portion is shown on the vertical axis, and a ratio (%) of the difference between the resonance frequency of the main vibration portion and the resonance frequency of the sub-vibration portion to the resonance frequency of the main vibration portion is shown on the horizontal axis.

As shown in fig. 15, the resonance amplitude of the sub-vibration portion 110s is smaller than the resonance amplitude of the main vibration portion 110 m. When the resonance frequency of the sub-vibration part 110s is higher than the resonance frequency of the main vibration part 110m, the resonance amplitude of the sub-vibration part 110s becomes larger as the resonance frequency of the sub-vibration part 110s approaches the resonance frequency of the main vibration part 110 m.

When the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s to the resonance frequency of the main vibration portion 110m is 7%, as indicated by a broken line La, the ratio of the resonance amplitude of the sub vibration portion 110s to the resonance amplitude of the main vibration portion 110m is 40%. When the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub vibration portion 110s to the resonance frequency of the main vibration portion 110m is 20%, as indicated by a broken line Lb, the ratio of the resonance amplitude of the sub vibration portion 110s to the resonance amplitude of the main vibration portion 110m is 18%. The larger the ratio of the resonance amplitude of the sub-vibration portion 110s to the resonance amplitude of the main vibration portion 110m is, the wider the angle range of directivity can be made.

As shown in fig. 15, when the resonance frequency of the sub-vibration portion 110s is higher than the resonance frequency of the main vibration portion 110m, and the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub-vibration portion 110s to the resonance frequency of the main vibration portion 110m is 7% or more and 20% or less, linearity is confirmed in the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub-vibration portion 110s to the resonance frequency of the main vibration portion 110m, and the ratio of the resonance amplitude of the sub-vibration portion 110s to the resonance amplitude of the main vibration portion 110 m.

As shown in fig. 14 and 15, when the resonance frequency of the sub-vibration portion 110s is higher than the resonance frequency of the main vibration portion 110m, and the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub-vibration portion 110s to the resonance frequency of the main vibration portion 110m is 7% or more and 20% or less, the phase difference between the resonance vibration of the main vibration portion 110m and the resonance vibration of the sub-vibration portion 110s can be set to 120 ° or more and 180 ° or less, and the resonance amplitude of the sub-vibration portion 110s can be set to 18% or more and 40% or less of the resonance amplitude of the main vibration portion 110 m.

Accordingly, by adjusting the resonance frequency of the sub-vibrating portion 110s in the range of 107% or more and 120% or less of the resonance frequency of the main vibrating portion 110m by changing the interval between the tubular body 120 and the restraining portion 140 in the 2 nd direction (X-axis direction), the phase difference between the resonance vibration of the main vibrating portion 110m and the resonance vibration of the sub-vibrating portion 110s can be set to be 120 ° or more and 180 ° or less, and the resonance amplitude of the sub-vibrating portion 110s can be appropriately selected in the range R of 18% or more and 40% or less of the resonance amplitude of the main vibrating portion 110m, so that at least one of transmission of high-sound-pressure ultrasonic waves and reception of high-sensitivity ultrasonic waves can be realized, and the directional angle range can be widened.

As described above, in the ultrasonic transducer 100 according to embodiment 1 of the present invention, the sub-vibration portion 110s is resonantly vibrated in an appropriate resonance mode without reducing the vibration portion of the main vibration portion 110m, and thereby, at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity can be realized while suppressing a narrowing of the angular range of directivity.

In the present embodiment, the case where the ultrasonic vibrator 130 is a piezoelectric vibrator has been described, but the ultrasonic vibrator 130 is not limited to a piezoelectric vibrator and may be an electrostatic or electromagnetic driven ultrasonic vibrator as long as the main vibration portion 110m and the sub vibration portion 110s can be driven in the same manner.

The shape of the constraining section 140 is not limited to a rectangular ring shape, as long as the resonance vibration of the sub-vibrating section 110s can be similarly generated. The restraint unit of the ultrasonic transducer according to each modification of embodiment 1 of the present invention will be described below.

Fig. 16 is a plan view showing a restraining portion according to modification 1. As shown in fig. 16, the restraining portion 140a according to modification 1 has a square annular shape. Fig. 17 is a plan view showing a restraining portion according to modification 2. As shown in fig. 17, in the restraining portion 140b according to modification 2, the outer shape is square, and the inner shape is circular. Fig. 18 is a plan view showing a restraining portion according to modification 3. As shown in fig. 18, in the restraining portion 140c according to modification 3, the outer shape is square, and the inner shape is hexagonal. Fig. 19 is a plan view showing a restriction portion according to modification 4. As shown in fig. 19, a constraint portion 140d according to modification 4 has a circular shape. Fig. 20 is a plan view showing a restriction portion according to modification 5. As shown in fig. 20, the restraining portion 140e according to modification 5 has a U-shape. Fig. 21 is a plan view showing a restraining portion according to modification 6. As shown in fig. 21, the shape of the restraining portion 140f according to the 6 th modification is a pair of straight lines extending in the 3 rd direction (Y-axis direction) while being spaced apart from each other in the 2 nd direction (X-axis direction).

In the present embodiment, the ultrasonic vibrator 130 is a so-called tandem bimorph piezoelectric vibrator, but the ultrasonic vibrator 130 may be another piezoelectric vibrator. An ultrasonic transducer of an ultrasonic transducer according to a modification of embodiment 1 of the present invention will be described below.

Fig. 22 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 7. As shown in fig. 22, an ultrasonic transducer 130a according to modification 7 is a piezoelectric element including 2 piezoelectric elements 131 stacked. The polarization directions Dp of the 2 piezoelectric bodies 131 are identical to each other. The ultrasonic vibrator 130a is a so-called parallel bimorph piezoelectric vibrator.

Fig. 23 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 8. As shown in fig. 23, an ultrasonic transducer 130b according to modification 8 is a piezoelectric element including 4 piezoelectric elements 131 stacked. The polarization direction Dp of the 2 piezoelectric bodies 131 located on the outer side among the 4 piezoelectric bodies 131 is directed to one of the 1 st direction (Z-axis direction), and the polarization direction Dp of the 2 piezoelectric bodies 131 located on the inner side among the 4 piezoelectric bodies 131 is directed to the other of the 1 st direction (Z-axis direction). The ultrasonic vibrator 130b is a so-called piezoelectric transducer of a piezoelectric multi-piezoelectric wafer type.

Fig. 24 is a cross-sectional view showing the structure of an ultrasonic transducer according to modification 9. As shown in fig. 24, an ultrasonic transducer 130c according to modification 9 is a piezoelectric element including 1 piezoelectric body 131. Specifically, the piezoelectric body 131 is sandwiched by the 1 st electrode 132 and the vibration plate 135 including metal. The ultrasonic vibrator 130c is a so-called unimorph piezoelectric vibrator.

Fig. 25 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to modification 10 of embodiment 1 of the present invention. As shown in fig. 25, an ultrasonic transducer 100a according to a 10 th modification of embodiment 1 of the present invention includes an exterior part 110, a tubular body 120a, an ultrasonic transducer, and a constraining part 140. The cylinder 120a has a bottomed cylindrical shape. The cylinder 120a is formed of metal. A piezoelectric body 131 is adhered to the bottom surface of the outer side of the cylinder 120a, and an ultrasonic transducer which is a unimorph piezoelectric transducer is formed.

In the ultrasonic transducer 100 according to embodiment 1 of the present invention, the main vibration portion 110m, which is a portion of the exterior portion 110 located inside the cylinder 120, resonates in a phase opposite to that of the ultrasonic vibrator 130, as viewed from the 1 st direction (Z-axis direction). The sub-vibration portion 110s, which is a portion of the exterior portion 110 located outside the cylinder 120 and inside the constraint portion 140 in the 2 nd direction (X-axis direction) as viewed from the 1 st direction (Z-axis direction), resonates in a range of 120 ° to 180 ° in absolute value of a phase difference of the resonant vibration with respect to the main vibration portion 110 m. This makes it possible to suppress narrowing of the angular range of directivity while achieving at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

In the ultrasonic transducer 100 according to embodiment 1 of the present invention, the restraint portion 140 has an annular shape. This can suppress occurrence of vibration leakage in the 3 rd direction (Y-axis direction) orthogonal to the 2 nd direction (X-axis direction) in which the angular range of directivity is widened.

In the ultrasonic transducer according to embodiment 1 of the present invention, the ultrasonic vibrator 130 is a piezoelectric element including a piezoelectric body. This makes it possible to simplify the structure of the ultrasonic transducer 100.

In the ultrasonic transducer according to embodiment 1 of the present invention, the resonance frequency of the sub-vibration portion 110s is higher than the resonance frequency of the main vibration portion 110m, and the ratio of the difference between the resonance frequency of the main vibration portion 110m and the resonance frequency of the sub-vibration portion 110s to the resonance frequency of the main vibration portion 110m is 7% or more and 20% or less. This makes it possible to widen the angular range of directivity while achieving at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

In the ultrasonic transducer according to embodiment 1 of the present invention, the relationship of 0.7CpTp/Cb and Tb and 1.3CpTp/Cb is satisfied when the sound velocity of the transverse wave of the exterior part 110 is Cb, the sound velocity of the transverse wave of the piezoelectric body 131 is Cp, the thickness of the main vibration part 110m is Tb, and the thickness of the piezoelectric body 131 is Tp. This can maintain physical balance between the main vibration unit 110m and the ultrasonic vibrator 130 during vibration, and suppress a decrease in the amplitude of the resonance vibration of the main vibration unit 110m and vibration leakage.

In the ultrasonic transducer according to embodiment 1 of the present invention, the resonance amplitude of the sub-vibration portion 110s is smaller than the resonance amplitude of the main vibration portion 110 m. Thereby, the sound pressure level in the front direction of the radiation angle θ=0° can be suppressed from becoming too low.

In the ultrasonic transducer according to embodiment 1 of the present invention, the resonance amplitude of the sub-vibrating portion 110s is 18% or more and 40% or less of the resonance amplitude of the main vibrating portion 110 m. This makes it possible to realize at least one of transmission of ultrasonic waves of high sound pressure and reception of ultrasonic waves of high sensitivity.

(Embodiment 2)

An ultrasonic transducer according to embodiment 2 of the present invention will be described below with reference to the drawings. The ultrasonic transducer according to embodiment 2 of the present invention is different from the ultrasonic transducer according to embodiment 1 of the present invention in that the tubular body and the restraint portion are attached to the inner surface of the exterior portion via the metal plate portion, and therefore, the same configuration as that of the ultrasonic transducer according to embodiment 1 of the present invention will not be described again.

Fig. 26 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 2 of the present invention. Fig. 27 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 2 of the present invention. As shown in fig. 26 and 27, an ultrasonic transducer 200 according to embodiment 2 of the present invention includes an exterior part 110, a tubular body 120, an ultrasonic transducer 130, a restraint part 140, and a metal plate part 250.

The cylindrical body 120 and the restraining portion 140 are each attached to the inner surface 111 via a metal plate portion 250 extending along the inner surface 111 of the outer housing portion 110. Specifically, a recess 112 is formed in the inner surface 111 of the outer housing 110. The thickness of the outer covering portion 110 of the portion where the recess 112 is formed is, for example, 1mm. The recess 112 may not necessarily be formed in the outer housing 110.

The metal plate portion 250 has a flat plate shape. The metal plate portion 250 is mounted in the recess 112. The tubular body 120 is attached to the center of the metal plate portion 250, and the restraint portion 140 is attached to the edge of the metal plate portion 250, as viewed from the 1 st direction (Z-axis direction). The metal plate portion 250 is formed of a metal such as aluminum. The thickness of the metal plate portion 250 is, for example, 0.5mm.

The main vibration portion 110m and the sub vibration portion 110s are each composed of a thinned portion of the exterior portion 110 in which the recess 112 is formed, and the metal plate portion 250.

By adding the metal plate portions 250 to the main vibration portion 110m and the sub vibration portion 110s, the sound velocity of the transverse wave of each of the main vibration portion 110m and the sub vibration portion 110s increases. On the other hand, the thickness of the main vibration portion 110m becomes thin. Accordingly, the thickness of the piezoelectric body 131 needs to be adjusted. When the thickness of the portion of the exterior part 110 where the recess 112 is formed is 1mm and the thickness of the metal plate part 250 containing aluminum is 0.5mm, the thickness of the piezoelectric body 131 is preferably 1mm or more and 1.5mm or less.

The resin such as polypropylene constituting the exterior part 110 is hard at low temperature and soft at high temperature. Accordingly, the resonance frequencies of the main vibration portion 110m and the sub vibration portion 110s vary according to the temperature.

In the ultrasonic transducer 200 according to embodiment 2 of the present invention, the metal plate portions 250 having little change in hardness due to temperature are added to the main vibration portion 110m and the sub vibration portion 110s, so that the change in resonance frequency due to temperature of each of the main vibration portion 110m and the sub vibration portion 110s can be reduced. As a result, the temperature characteristics of the ultrasonic transducer 200 can be stabilized.

In the ultrasonic transducer 200 according to embodiment 2 of the present invention, the thickness of the outer cover 110 constituting each of the main vibration portion 110m and the sub vibration portion 110s is reduced, so that the change in the resonance frequency of each of the main vibration portion 110m and the sub vibration portion 110s due to temperature can be reduced. This also stabilizes the temperature characteristics of the ultrasonic transducer 200.

Fig. 28 is a longitudinal sectional view showing the periphery of an ultrasonic transducer of the ultrasonic transducer according to modification 1 of embodiment 2 of the present invention. As shown in fig. 28, in the ultrasonic transducer according to modification 1 of embodiment 2 of the present invention, an internal space formed by the tubular body 120 and the metal plate portion 250 is filled with a damping material 260 such as silicone. This can suppress the generation of unnecessary radiation and reverberation of the ultrasonic wave to the side opposite to the exterior part side. The Young's modulus of the damping material 260 is, for example, 0.1MPa or more and 100MPa or less. The young's modulus of the damping material 260 is preferably 0.1MPa or more and 0.5MPa or less from the viewpoint of suppressing the radiation of unnecessary ultrasonic waves to the side opposite to the exterior part side, and the young's modulus of the damping material 260 is preferably 10MPa or more and 50MPa or less from the viewpoint of suppressing reverberation.

Fig. 29 is a perspective view showing a cylindrical body and a metal plate portion of an ultrasonic transducer according to modification 2 of embodiment 2 of the present invention. As shown in fig. 29, in the ultrasonic transducer according to modification 2 of embodiment 2 of the present invention, the tubular body 120 and the metal plate portion 250 are integrally formed. Specifically, the cylinder 120 and the metal plate portion 250 are formed of a bottomed tubular metal member. In this modification, vibration leakage from the interface between the cylindrical body 120 and the metal plate portion 250 can be suppressed.

Embodiment 3

An ultrasonic transducer according to embodiment 3 of the present invention will be described below with reference to the drawings. The ultrasonic transducer according to embodiment 3 of the present invention differs from the ultrasonic transducer according to embodiment 2 of the present invention in that a slit is formed in a metal plate portion, and therefore, the same configuration as that of the ultrasonic transducer according to embodiment 2 of the present invention will not be described again.

Fig. 30 is a longitudinal sectional view showing the structure of an ultrasonic transducer according to embodiment 3 of the present invention. Fig. 31 is an exploded perspective view showing the structure of an ultrasonic transducer according to embodiment 3 of the present invention. As shown in fig. 30 and 31, an ultrasonic transducer 300 according to embodiment 3 of the present invention includes an exterior part 110, a cylindrical body 120, an ultrasonic transducer 130, a restraint part 140, and a metal plate part 350.

In the present embodiment, a slit 351 extending along the outer edge of the cylindrical body 120 is formed in a position of the metal plate portion 350 overlapping the sub-vibration portion 110s, as viewed from the 1 st direction (Z-axis direction). The slit 351 extends in the 3 rd direction (Y-axis direction). The slit 351 is intermittently formed in the 3 rd direction (Y-axis direction). Specifically, the slit 351 is formed at the position of the center portion and both end portions of the cylinder 120 in the 3 rd direction (Y-axis direction).

In the present embodiment, a slit 352 extending in the 2 nd direction (X-axis direction) along the outer edge of the cylinder 120 is formed in the metal plate portion 350. The slit 351 and the slit 352 are formed in a substantially rectangular shape as viewed from the 1 st direction (Z-axis direction).

Here, the results of simulation analysis of the relationship between the resonant frequency of each of the main vibration portion 110m and the sub vibration portion 110s and the length of the slit 351 will be described using the finite element method. Fig. 32 is a perspective view showing a metal plate portion and a cylindrical body according to a comparative example. Fig. 33 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 1. Fig. 34 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 2. Fig. 35 is a perspective view showing a metal plate portion and a cylindrical body according to embodiment 3.

As shown in fig. 32, the slit 351 is not formed in the metal plate portion 950 according to the comparative example. As shown in fig. 33, in the metal plate portion 350a according to embodiment 1, a slit 351 having a length of 4mm is formed in the center portion in the 3 rd direction (Y-axis direction). As shown in fig. 34, in the metal plate portion 350b according to embodiment 2, slits 351 having a length of 8mm are formed from the central portion toward the both end portions in the 3 rd direction (Y-axis direction). As shown in fig. 35, in the metal plate portion 350c according to embodiment 3, slits 351 having a length of 12mm are formed from the central portion toward the both end portions in the 3 rd direction (Y-axis direction).

Fig. 36 is a graph showing the relationship between the resonant frequency of each of the main vibration portion and the sub vibration portion and the length of the slit. In fig. 36, the resonance frequencies (kHz) of the main vibration portion and the sub vibration portion are shown on the vertical axis, and the lengths (mm) of the slits are shown on the horizontal axis. The resonance frequency of the main vibrating portion is shown by a solid line, and the resonance frequency of the sub vibrating portion is shown by a broken line.

As shown in fig. 36, as the length of the slit 351 increases, the resonance frequency of each of the main vibration portion 110m and the sub vibration portion 110s decreases. In particular, as the length of the slit 351 becomes longer, the resonance frequency of the sub-vibrating portion 110s significantly decreases.

As is clear from the simulation analysis results, the resonance frequency of the sub-vibration portion 110s can be reduced by forming the slit 351 extending along the outer edge of the cylindrical body 120 at the position of the metal plate portion 350 overlapping the sub-vibration portion 110s as viewed in the 1 st direction (Z-axis direction). Therefore, by forming the slit 351 of an appropriate length while reducing the interval between the cylinder 120 and the constraining section 140 in the 2 nd direction (X-axis direction), the ultrasonic transducer 300 can be miniaturized while maintaining the resonance frequency of the sub-vibrating section 110 s. By reducing the interval between the cylinder 120 and the restriction 140 in the 2 nd direction (X-axis direction), vibration leakage can be reduced.

Fig. 37 is a perspective view showing a cylindrical body and a metal plate portion of an ultrasonic transducer according to a modification of embodiment 3 of the present invention. As shown in fig. 37, in the ultrasonic transducer according to the modification of embodiment 3 of the present invention, the tubular body 120 and the metal plate portion 350 are integrally formed. Specifically, the cylinder 120 and the metal plate portion 350 are formed of a bottomed tubular metal member. In this modification, vibration leakage from the interface between the cylindrical body 120 and the metal plate portion 350 can be suppressed.

In the description of the above embodiments, the combinable structures may be combined with each other.

The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the appended claims, rather than by the description given above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Description of the reference numerals

100. 100A, 200, 300 ultrasonic transducers;

110. An outer part;

110m main vibration part;

110s auxiliary vibrating part;

111. An inner surface;

112. A concave portion;

120. 120a cylinder;

130. 130a, 130b, 130c ultrasonic vibrators;

131. a piezoelectric body;

132. 1 st electrode;

133. a2 nd electrode;

134. an intermediate electrode;

135. A vibration plate;

140. 140a, 140b, 140c, 140d, 140e, 140 f;

150. A processing circuit;

250. 350, 350a, 350b, 350c, 950 sheet metal portions;

260. Damping material;

351. 352 slit.

Claims (10)

1. An ultrasonic transducer is provided with:

an outer part having an inner surface;

A cylinder mounted on the inner surface;

an ultrasonic vibrator mounted on the cylinder and facing the inner surface with a space therebetween; and

A restraining part mounted on the inner surface and sandwiching the cylinder with a space therebetween,

A main vibration portion, which is a portion of the exterior part located inside the cylinder, resonates in a phase opposite to that of the ultrasonic vibrator as viewed from the 1 st direction orthogonal to the inner surface,

The secondary vibration portion, which is a portion of the exterior portion located outside the cylinder and inside the constraining portion in the 2 nd direction orthogonal to the 1 st direction, resonates in a range of 120 ° to 180 ° in absolute value of a phase difference of the resonant vibration with respect to the primary vibration portion, as viewed from the 1 st direction.

2. The ultrasonic transducer according to claim 1, wherein,

The restraining portion has a ring-like shape.

3. The ultrasonic transducer according to claim 1 or claim 2, wherein,

The ultrasonic vibrator is a piezoelectric element including a piezoelectric body.

4. An ultrasonic transducer according to any one of claim 1 to claim 3 wherein,

The cylinder and the restraining portion are each mounted on the inner surface via a metal plate portion extending along the inner surface.

5. The ultrasonic transducer of claim 4, wherein,

A slit extending along an outer edge of the cylindrical body is formed at a position of the metal plate portion overlapping the sub-vibration portion as viewed from the 1 st direction.

6. The ultrasonic transducer according to claim 4 or claim 5, wherein,

A recess is formed in the inner surface,

The metal plate portion is mounted in the recess.

7. The ultrasonic transducer according to any one of claim 1 to claim 6, wherein,

The resonance frequency of the secondary vibrating portion is higher than the resonance frequency of the primary vibrating portion,

The difference between the resonance frequency of the secondary vibration portion and the resonance frequency of the primary vibration portion is 7% or more and 20% or less of the resonance frequency of the primary vibration portion.

8. The ultrasonic transducer according to claim 3, wherein,

If the sound velocity of the transverse wave of the exterior part is Cb, the sound velocity of the transverse wave of the piezoelectric body is Cp, the thickness of the main vibration part is Tb, and the thickness of the piezoelectric body is Tp

Satisfies the relationship of 0.7 CpTp/Cb.ltoreq.Tb.ltoreq.1.3 CpTp/Cb.

9. The ultrasonic transducer according to any one of claim 1 to claim 8, wherein,

The resonance amplitude of the secondary vibration portion is smaller than the resonance amplitude of the primary vibration portion.

10. The ultrasonic transducer of claim 9, wherein,

The resonance amplitude of the secondary vibration portion is 18% to 40% of the resonance amplitude of the primary vibration portion.