Ultrasonic transducer

Abstract

The present invention discloses an ultrasonic transducer. The ultrasonic transducer comprises: a shell, a transducer housing and at least one ultrasonic transmitting unit for transmitting ultrasonic waves, wherein the transducer housing and the ultrasonic transmitting unit are located inside the shell, and the ultrasonic transmitting unit is located on the transducer housing; the inner surface of the transducer housing is an ultrasonic transmitting surface and has the function of reflecting ultrasonic waves, and the inner surface of the transducer housing forms a resonance cavity; the ultrasonic waves emitted by the inner surface of the transducer housing and the reflected waves formed by the reflection of the ultrasonic waves by the inner surface of the transducer housing are focused on the focal area of ​​the ultrasonic transmitting unit. The ultrasonic transducer provided by the present invention realizes resonant focusing and can withstand high hydrostatic pressure, thereby further improving the sound pressure in the focal area.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic technology, and in particular to an ultrasonic transducer. Background Art

[0002] After focusing ultrasound, an area with highly concentrated energy can be obtained, which is called the focal zone.

[0003] Taking advantage of this feature, China has taken the lead in developing this technology into high-intensity focused ultrasound tumor treatment equipment, and has applied it to the clinical treatment of benign and malignant tumors such as liver tumors, kidney tumors, bone tumors, and uterine fibroids, achieving good results in treatment safety, effectiveness, and economy, and gradually forming a new direction of minimally invasive treatment technology.

[0004] Existing ultrasonic focusing methods, such as spherical shell focusing, lens focusing, reflector focusing, phased focusing, etc., are all traveling wave focusing methods. The highest sound pressure achieved by the traveling wave focusing method is 10 7 Pa order of magnitude (continuous wave), the minimum focal size is of the wavelength order, so the focal energy is difficult to further increase.

[0005] However, in the prior art, there is no ultrasonic transducer that can further increase the focal sound pressure. Summary of the invention

[0006] The present invention provides an ultrasonic transducer for further improving the sound pressure in a focal region.

[0007] To achieve the above object, the present invention provides an ultrasonic transducer, comprising: a housing, a transducer housing, and at least one ultrasonic transmitting unit for transmitting ultrasonic waves, wherein the transducer housing and the ultrasonic transmitting unit are located inside the housing, and the ultrasonic transmitting unit is located on the transducer housing;

[0008] The inner surface of the transducer housing is an ultrasonic emitting surface and has the function of reflecting ultrasonic waves, and the inner surface of the transducer housing forms a resonance cavity;

[0009] The ultrasonic wave emitted by the inner surface of the transducer housing and the reflected wave formed by the inner surface of the transducer housing reflecting the ultrasonic wave are focused on the focal area of ​​the ultrasonic transmitting unit.

[0010] Optionally, the transducer housing has a function of a matching layer.

[0011] Optionally, the shape of the transducer shell is a spherical shell or a truncated spherical shell including the center of the sphere, and the focal area of ​​the ultrasonic transmitting unit is the center position of the transducer shell.

[0012] Optionally, the ultrasonic transmitting unit is located on the outer surface of the transducer housing.

[0013] Optionally, the inner surface of the transducer housing is a mirror surface.

[0014] Optionally, the transducer housing is made of aluminum alloy or titanium aluminum alloy.

[0015] Optionally, there are multiple ultrasonic transmitting units, and each ultrasonic transmitting unit is a piezoelectric array element.

[0016] Optionally, it further comprises: a first backing and a second backing;

[0017] The first backing is located on the ultrasonic transmitting unit, and the second backing is filled between the shell and the first backing.

[0018] Optionally, the material of the first backing includes a mixture of tungsten powder and epoxy material;

[0019] The material of the second backing includes epoxy material or oil.

[0020] Optionally, the operating frequency of the ultrasonic transmitting unit is 400kHz to 1200kHz.

[0021] Optionally, the ultrasonic transducer can withstand a hydrostatic pressure greater than or equal to 10 MPa.

[0022] The present invention has the following beneficial effects:

[0023] In the technical solution of the ultrasonic transducer provided by the present invention, the ultrasonic transducer includes a shell, a transducer shell and at least one ultrasonic transmitting unit. The transducer shell and the ultrasonic transmitting unit are located inside the shell, and the ultrasonic transmitting unit is located on the transducer shell. The ultrasonic transducer provided by the present invention realizes resonant focusing and can withstand high hydrostatic pressure, thereby further improving the sound pressure in the focal area. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of an ultrasonic transducer provided in Embodiment 1 of the present invention;

[0025] Figure 2 Schematic diagram of sound wave propagation in the transducer housing. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the ultrasonic transducer provided by the present invention is described in detail below with reference to the accompanying drawings.

[0027] Figure 1 A schematic diagram of the structure of an ultrasonic transducer provided in Embodiment 1 of the present invention is shown in FIG. Figure 1As shown, the ultrasonic transducer comprises: a housing 1, a transducer housing 2 and at least one ultrasonic transmitting unit 3 for transmitting ultrasonic waves. The transducer housing 2 and the ultrasonic transmitting unit 3 are located inside the housing 1, and the ultrasonic transmitting unit 3 is located on the transducer housing 2.

[0028] The inner surface of the transducer housing 2 is an ultrasonic emission surface and has the function of reflecting ultrasonic waves, and the inner surface of the transducer housing 2 forms a resonance cavity. The ultrasonic waves emitted by the inner surface of the transducer housing 2 and the reflected waves formed by the reflection of the ultrasonic waves by the inner surface of the transducer housing 2 are focused on the focal area of ​​the ultrasonic emission unit 3. Preferably, the ultrasonic emission unit 3 is located on the outer surface of the transducer housing 2. The ultrasonic waves emitted by the ultrasonic emission unit 3 penetrate the transducer housing 2, and propagate to the focal area through the inner surface of the transducer housing 2, and continue to propagate to the inner surface of the transducer housing 2 after passing through the focal area, and form reflected waves on the inner surface of the transducer housing 2.

[0029] The transducer housing 2 has the function of a matching layer. The matching layer is an important component of the ultrasonic transducer. The function of the matching layer is to match the acoustic impedance difference between the ultrasonic transmitting unit and the medium (such as water) of the ultrasonic transducer, and to achieve acoustic impedance matching or transition, so that the acoustic energy transmittance between the ultrasonic transmitting unit and the medium water is greatly improved. At the same time, the bandwidth of the ultrasonic transducer can be widened, so that the acoustic wave energy utilization rate of the transducer is improved, and the performance is improved. For a given frequency, the thickness of the matching layer is 1 / 4λ in principle, but the thickness will be corrected according to the experimental data of the ultrasonic transducer. The method is to first simulate and design according to the bandwidth and electroacoustic conversion efficiency of the ultrasonic transducer, and then determine the thickness of the matching layer according to the experimental results. The thickness of the determined matching layer is determined as the thickness of the transducer housing 2.

[0030] Preferably, the shape of the transducer housing 2 is a spherical shell or a truncated spherical shell including the center of the sphere, and the focal area of ​​the ultrasonic transmitting unit 3 is the center position of the sphere of the transducer housing 2. In this embodiment, the shape of the transducer housing 2 is a truncated spherical shell including the center of the sphere, specifically, the shape of the transducer housing 2 is a spherical table, for example, the shape of the transducer housing 2 is a drum. In practical applications, the shape of the transducer housing 2 can also be other shapes, which are not listed here one by one.

[0031] The transducer housing 2 is the core part of the ultrasonic transducer. Figure 2 is a schematic diagram of sound wave propagation in the transducer housing, as shown in Figure 2As shown, the ultrasonic wave emitted by the ultrasonic transmitting unit 3 penetrates the transducer housing 2, propagates to the spherical center position O through the inner surface of the transducer housing 2, and continues to propagate to the inner surface of the transducer housing 2 after passing the spherical center position O, and then forms a reflected wave through reflection from the inner surface of the transducer housing 2. When the transducer housing 2 meets the resonance condition, that is, when the inner surface of the transducer housing 2 forms a resonance cavity, the ultrasonic wave directly focused at the spherical center position O and the reflected wave have the same phase, so that a superposition of sound waves can be formed at the spherical center position O, so that a stable sound field distribution with high intensity is formed in the resonance cavity, so that a high sound pressure is reached at the spherical center position O, thereby increasing the sound pressure in the focal area.

[0032] Since the inner surface of the transducer housing 2 is used as the ultrasonic emission surface, the transducer housing 2 needs to transmit the ultrasonic waves emitted by the ultrasonic emission unit 3 as much as possible. In this embodiment, the ultrasonic transducer needs to set the transmittance, and the formula of the transmittance is: τ = 4Z1Z2 / (Z2+Z1) 2 , where τ is the transmittance, Z1 is the impedance of the ultrasonic transmitting unit 3, and Z2 is the impedance of the transducer housing 2. The material of the transducer housing 2 can be selected by the above formula so that the ultrasonic transducer obtains a larger transmittance. Preferably, the material of the transducer housing 2 is an aluminum alloy. From the above formula, it can be concluded that the transmittance of the transducer housing 2 is greater than 90%, thereby meeting the transmittance requirements of the ultrasonic transducer. In practical applications, optionally, the material of the transducer housing 2 can also be a titanium aluminum alloy.

[0033] The inner surface of the transducer housing 2 also serves as a reflecting surface. The inner surface of the transducer housing 2 reflects the ultrasonic wave to form a reflected wave. When the transducer housing 2 meets the resonance condition, the transducer housing 2 reflects the ultrasonic wave reaching the inner surface back to the spherical center position O as much as possible, so that the energy is superimposed at the spherical center position O to increase the sound pressure at the spherical center position O. In order to make the transducer housing 2 reflect the ultrasonic wave reaching the inner surface back to the spherical center position O as much as possible, the inner surface of the transducer housing 2 can be processed into a mirror surface or a quasi-mirror surface. Preferably, the inner surface of the transducer housing 2 is a mirror surface, so that the ultrasonic wave is strongly reflected on the inner surface of the transducer housing 2 to form a reflected wave. When resonance occurs, the ultrasonic wave and the reflected wave are superimposed at the spherical center position O, so as to achieve the purpose of increasing the sound pressure at the spherical center position O.

[0034] The ultrasonic transmitting unit 3 is located on the outer surface of the transducer housing 2. Specifically, multiple ultrasonic transmitting units 3 can be attached to the outer surface of the transducer housing 2. At this time, the transducer housing 2 is a supporting housing for the ultrasonic transmitting unit 3. Preferably, the number of ultrasonic transmitting units 3 is multiple, and the ultrasonic transmitting unit 3 is a piezoelectric array element. For example, the material of the piezoelectric array element is piezoelectric ceramic or 1-3 type piezoelectric composite material. Multiple ultrasonic transmitting units 3 adopt an array element combined structure. In this embodiment, the parameters of the piezoelectric array element can be designed according to the shape and focusing requirements of the transducer housing 2. The influence of the number and arrangement of the piezoelectric array elements on the focusing performance and sound pressure can be studied by numerical simulation. The results show that the sound pressure at the focal area (center position O) is proportional to the number of piezoelectric array elements. Multiple piezoelectric array elements are arranged in sequence on the outer surface of the transducer housing 2. Preferably, multiple piezoelectric array elements are arranged on the outer surface of the transducer housing 2 in an equidistant and dense manner, which is conducive to suppressing the side lobes of ultrasonic waves. In addition, the vibration mode of the piezoelectric array element adopts a thickness vibration mode to improve its electroacoustic conversion efficiency.

[0035] Furthermore, the ultrasonic transducer further includes: a first backing 4. The first backing 4 is located on the ultrasonic transmitting unit 3. Specifically, the first backing 4 is located on the surface of the ultrasonic transmitting unit 3 close to the shell 1. Preferably, the material of the first backing 4 is a mixture of tungsten powder and epoxy material. During the manufacturing process, the ratio of tungsten powder and epoxy material can be set and a mixture can be formed according to the set ratio, and the mixture of tungsten powder and epoxy material formed according to the set ratio is made into a molded block, and the mixture made into a molded block is ground into a shape matching the ultrasonic transmitting unit 3, and the mixture is pasted on the surface of the ultrasonic transmitting unit 3 close to the shell 1, so as to achieve the first backing 4 being pasted on the surface of the ultrasonic transmitting unit 3 close to the shell 1.

[0036] Furthermore, the ultrasonic transducer further includes: a second backing 5. The second backing 5 is filled between the housing 1 and the first backing 4. Preferably, the material of the second backing 5 is an epoxy material. In this embodiment, the epoxy material can be used to fill the epoxy material between the housing 1 and the first backing 4, so that the ultrasonic transducer forms a rigid structure, thereby improving the pressure resistance of the ultrasonic transducer. Preferably, the thickness of the second backing 5 ranges from 2 mm to 10 mm.

[0037] In practical applications, the material of the second backing 5 can optionally be oil, for example, castor oil. In this case, the distance between the first backing 4 and the housing 1 can be set to be smaller, for example, 2 mm. In this case, before the ultrasonic transducer is installed, the gap between the first backing 4 and the ultrasonic transmitting unit 3 can be filled with a polymer material.

[0038] In this embodiment, a double-layer backing structure of a first backing 4 and a second backing 5 is adopted. In the double-layer backing structure, the mixture of tungsten powder and epoxy material of the first backing 4 has a high acoustic impedance characteristic, which can improve the acoustic attenuation performance of the ultrasonic transducer, so that most of the ultrasonic waves emitted by the ultrasonic transmitting unit 3 are emitted to the focal area (center position O) through the inner surface of the transducer housing 2, thereby improving the performance of the ultrasonic transducer; in the double-layer backing structure, the second backing 5 can use the fluidity of epoxy to fill each gap, so that the ultrasonic transducer forms a good rigid structure and has good process feasibility. This embodiment adopts a double-layer backing structure to improve the pressure resistance of the entire ultrasonic transducer.

[0039] Furthermore, the ultrasonic transducer further comprises: an upper end cover 6 and a lower end cover 7. The upper end cover 6 is located above the transducer housing 2, and the upper end cover 6 is mounted on the transducer housing 2; the lower end cover 7 is located below the transducer housing 2, and the lower end cover 7 is mounted on the transducer housing 2.

[0040] Furthermore, the ultrasonic transducer further comprises: a first sealing structure 8. The first sealing structure 8 is used to seal the upper end cover 6. Preferably, the first sealing structure 8 is a sealing ring, for example: an O-type sealing ring.

[0041] Furthermore, the ultrasonic transducer further comprises: a second sealing structure 9. The second sealing structure 9 is used to seal the lower end cover 7. Preferably, the second sealing structure 9 is a sealing ring, for example: an O-type sealing ring.

[0042] In this embodiment, the ultrasonic transducer uses double O-rings to seal the upper end cover and the lower end cover, thereby achieving a good sealing effect.

[0043] Furthermore, the ultrasonic transducer includes: a connection seat 10 and a power aviation plug connector 11. Preferably, the connection seat 10 is a pressure-resistant connection seat, and the power aviation plug connector 11 is a pressure-resistant power aviation plug connector. The connection seat 10 and the power aviation plug connector 11 both adopt a watertight joint and an integrated vulcanized cable method, and the sealing method adopts a sealing ring sealing and a rubber vulcanization sealing process. Double sealing is adopted for the installation surface of the connection seat 10 and the power aviation plug connector 11, and at the same time, each electrical connection and each core adopts a quadruple sealing ring sealing. After each set of connection seat 10 and power aviation plug connector 11 is manufactured, a rubber fully sealed vulcanization process is adopted for the tail of each connection seat 10 and power aviation plug connector 11 to ensure that the hydrostatic pressure that can be tolerated is ≥10MPa. When installing the connection seat 10 and the power aviation plug connector 11, apply special pressure-resistant sealing grease to ensure sealing and pressure resistance indicators. At the same time, the connection cable of the connection seat 10 and the power aviation plug connector 11 is a specially customized cable that meets the pressure resistance requirements. After each set of cables is manufactured, strict pressure resistance tests and related technical indicators are tested.

[0044] In this embodiment, the width of the transducer housing 2 is 200 mm to 1000 mm. For example, when the shape of the transducer housing 2 is a spherical shell or a spherical shell including the center of the sphere, the diameter of the transducer housing 2 is 200 mm to 1000 mm.

[0045] In this embodiment, the operating frequency of the ultrasonic transmitting unit 3 is 400KHz to 1200kHz.

[0046] In this embodiment, the hydrostatic pressure that the ultrasonic transducer can withstand is greater than or equal to 10 MPa. The ultrasonic transducer has the characteristics of high hydrostatic pressure resistance, thereby achieving the purpose of suppressing medium cavitation and increasing the cavitation threshold. The ultrasonic transducer in this embodiment can be used in deep water, pressurized or normal pressure environments.

[0047] In this embodiment, the sound pressure in the focal area is greater than or equal to 10 9 Pa.

[0048] In the technical solution of the ultrasonic transducer provided in this embodiment, the ultrasonic transducer includes a shell, a transducer shell and at least one ultrasonic transmitting unit. The transducer shell and the ultrasonic transmitting unit are located inside the shell, and the ultrasonic transmitting unit is located on the transducer shell. The ultrasonic transducer provided in this embodiment realizes resonant focusing and can withstand high hydrostatic pressure, thereby further improving the sound pressure in the focal area. The inner surface of the transducer shell of the present invention is both an ultrasonic transmitting surface and a sound wave reflecting surface, and the transducer shell is a matching layer. Through ultrasonic transducer frequency tracking and compensation, phase control, ultrasonic wave emission and reflection, sound wave resonant focusing is realized, and a stable spherical standing wave focusing sound field and a sub-wavelength fine focal area can be realized, so that the ultrasonic transducer can obtain 10 9 Pa high sound pressure, thus providing a new research platform for scientific research.

[0049] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An ultrasonic transducer, characterized in that: include: A housing, a transducer housing and at least one ultrasonic transmitting unit for transmitting ultrasonic waves, wherein the transducer housing and the ultrasonic transmitting unit are located inside the housing, and the ultrasonic transmitting unit is located on the transducer housing; The inner surface of the transducer housing is an ultrasonic emitting surface and has the function of reflecting ultrasonic waves, and the inner surface of the transducer housing forms a resonance cavity; The ultrasonic wave emitted by the inner surface of the transducer housing and the reflected wave formed by the inner surface of the transducer housing reflecting the ultrasonic wave are focused on the focal area of ​​the ultrasonic transmitting unit; There are multiple ultrasonic transmitting units, each of which is a piezoelectric array element; the multiple piezoelectric array elements are arranged on the outer surface of the transducer housing in an equidistant manner; The ultrasonic transducer further comprises a double-layer backing structure of a first backing and a second backing; the first backing is located on a surface of the ultrasonic transmitting unit close to the shell, and the second backing is filled between the shell and the first backing; The material of the first backing includes a mixture of tungsten powder and epoxy material; the tungsten powder and the epoxy material are mixed in a set ratio, and the mixture is formed into a block shape, the block-shaped mixture is ground into a shape matching the ultrasonic transmitting unit, and the mixture is pasted on the surface of the ultrasonic transmitting unit on the side close to the shell, so as to achieve the first backing being pasted on the surface of the ultrasonic transmitting unit on the side close to the shell; The material of the second backing includes epoxy material or oil.

2. The ultrasonic transducer according to claim 1, characterized in that: The transducer housing has the function of a matching layer.

3. The ultrasonic transducer according to claim 1 or 2, characterized in that: The shape of the transducer shell is a spherical shell or a truncated spherical shell including the center of the sphere, and the focal area of ​​the ultrasonic transmitting unit is the center position of the sphere of the transducer shell.

4. The ultrasonic transducer according to claim 1, characterized in that: The ultrasonic transmitting unit is located on the outer surface of the transducer housing.

5. The ultrasonic transducer according to claim 1, characterized in that: The inner surface of the transducer housing is a mirror surface.

6. The ultrasonic transducer according to claim 1, characterized in that: The material of the transducer housing is aluminum alloy or titanium aluminum alloy.

7. The ultrasonic transducer according to claim 1, characterized in that: The operating frequency of the ultrasonic transmitting unit is 400kHz to 1200kHz.

8. The ultrasonic transducer according to claim 1, characterized in that: The ultrasonic transducer can withstand a hydrostatic pressure greater than or equal to 10 MPa.

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