Ultrasonic transducer

Abstract

An ultrasonic transducer of increasing a signal-to-noise ratio includes a shock absorption layer, a transducing module and an acoustic lens. The transducing module is disposed on the shock absorption layer. The acoustic lens is disposed on the transducing module and opposite to the shock absorption layer, and includes a plurality of flake structures having the same curvature. A structural height of each of the plurality of flake structures is defined as having a preset difference compared to a substrate thickness. An applied wavelength of the ultrasonic transducer is derived from a central frequency of the ultrasonic transducer and a sound speed of the acoustic lens. The substrate thickness is a sum of an integral multiple of half of the applied wavelength and one eighth of the applied wavelength. The preset difference is a numerical range greater than zero and smaller than or equal to one quarter of the applied wavelength.

Description

[Technical Field]

[0001] The present invention provides an ultrasonic transducer, and more particularly an ultrasonic transducer that can improve the signal-to-noise ratio. [Previous Technology]

[0002] Traditional ultrasound transducers include a damping layer, an acoustic lens, a piezoelectric material layer, and an acoustic impedance matching layer. The piezoelectric material layer is located on the damping layer near the acoustic lens, and the acoustic impedance matching layer is located between the piezoelectric material layer and the acoustic lens. The emitting surface of a traditional ultrasound transducer is a rectangular surface with a major axis and a minor axis. The curvature of the emitting surface causes the ultrasound waves to not have an ideal focusing effect in the minor axis direction, resulting in uneven energy distribution. In other words, traditional ultrasound transducers exhibit additional energy distribution in the minor axis direction, causing sidelobe effects and significantly attenuating the ultrasound wave energy due to diffusion. Therefore, designing an ultrasound transducer that can improve the signal-to-noise ratio and avoid sidelobe effects is one of the development issues in the related medical device industry. [Summary of the Invention]

[0003] The present invention provides an ultrasonic transducer that can improve the signal-to-noise ratio, thereby solving the above-mentioned problems.

[0004] The scope of this patent application discloses an ultrasonic transducer that can improve the signal-to-noise ratio, comprising a damping layer, a transducer module, and an acoustic lens. The transducer module is disposed on the damping layer. The acoustic lens is disposed on one side of the transducer module opposite to the damping layer, and has a plurality of sheet-like structures with the same curvature. The structural height of each of the plurality of sheet-like structures is defined as having a predetermined difference relative to the thickness of a substrate. An application wavelength of the ultrasonic transducer is derived from a center frequency of the ultrasonic transducer and a sound velocity of the acoustic lens. The substrate thickness is the sum of an integer multiple of half the application wavelength and one-eighth of the application wavelength. The predetermined difference is a numerical range greater than zero and less than or equal to one-quarter of the application wavelength.

[0005] The ultrasonic transducer of the present invention can significantly shorten the film thickness of the acoustic lens without changing its radius of curvature, so that the protrusion height of each sheet structure of the acoustic lens relative to the substrate can be far away from the sum of an integer multiple of the application wavelength and one-eighth of the application wavelength. That is, the predetermined difference between the structural height of the sheet structure and the thickness of the substrate can reach a value range that is greater than zero and less than or equal to one-quarter of the application wavelength. It has the advantages of increasing the overall signal strength and reducing the sidelobe effect, thereby effectively improving the signal-to-noise ratio of the ultrasonic transducer.

Implementation Method

[0006] Please refer to Figure 1, which is a schematic diagram of the structure of the ultrasonic transducer 10 according to an embodiment of the present invention. The ultrasonic transducer 10 may include at least a damping layer 12, a transducer module 14, and an acoustic lens 16. The damping layer 12 may be an adhesive-backed material. The transducer module 14 may include a piezoelectric material layer and an acoustic impedance matching layer (not marked in the figure); the acoustic impedance matching layer is located between the damping layer 12 and the acoustic lens 16, and the piezoelectric material layer is located between the damping layer 12 and the acoustic impedance matching layer. The acoustic lens 16 may be disposed on the side of the transducer module 14 opposite to the damping layer 12. The acoustic lens 16 of the present invention has a special design, which not only reduces the thickness of the acoustic lens 16, but also has the effect of eliminating artifacts and preventing sidelobe effects to improve the signal-to-noise ratio.

[0007] The acoustic lens 16 is located in the ultrasonic transmission path of the ultrasonic transducer 10 and can serve as an acoustic impedance matching layer (meaning it can be considered part of the acoustic impedance matching layer). The function of the acoustic impedance matching layer is to reduce ultrasonic reflection and improve energy transfer efficiency. The application wavelength of the ultrasonic transducer 10 can be derived from the center frequency of the ultrasonic transducer 10 and the sound velocity of the acoustic lens 16; for example, if the center frequency is 10 MHz and the sound velocity is 1 mm / µs, the application wavelength can be calculated to be 0.1 mm. The actual value depends on the product specifications and will not be explained in detail here.

[0008] Therefore, if the thickness of the acoustic impedance matching layer is an odd multiple of one-quarter of the applied wavelength, the ultrasound wave will be reflected within the acoustic lens 16 (or between the acoustic impedance matching layer and the external medium), and the reflected wave and the incident wave will cancel each other out due to their opposite phases. If the thickness of the acoustic impedance matching layer is half of the applied wavelength, the ultrasound wave reflected within the acoustic lens 16 will have the same phase as the incident wave, and the energy will not be reflected through the acoustic impedance matching layer. The remaining areas will exhibit partial reflection and partial refraction. Therefore, in accordance with the above principle, the present invention designs the acoustic lens 16 as a modified Fresnel lens to improve the signal-to-noise ratio.

[0009] Please refer to Figure 2, which is a simplified structural diagram of the acoustic lens 16 according to the first embodiment of the present invention. The acoustic lens 16 may have a plurality of sheet-like structures 18 with the same curvature, and one end of the plurality of sheet-like structures 18 adjacent to the transducer module 14 is defined as the substrate 20. The plurality of sheet-like structures 18 have the same structural height H, and the substrate 20 has a substrate thickness W; moreover, the structural height H may have a predetermined difference from the substrate thickness W in order to reduce the sidelobe effect. In the first embodiment, the substrate thickness W may be the sum of an integer multiple of half the application wavelength (e.g., zero or a positive integer) and one-eighth of the application wavelength, and the predetermined difference may be designed to be a numerical range greater than zero and less than or equal to one-quarter of the application wavelength; in other words, the structural height H is preferably designed to be the sum of the substrate thickness W and one-quarter of the application wavelength, with a thinner film thickness and only a slight energy attenuation, which is a preferred embodiment; however, the actual application is not limited to this.

[0010] Furthermore, in the first embodiment, the vertex direction Dt of the two sheet-like structures 18 is oriented towards the center of the acoustic lens 16; however, practical applications are not limited to this. The present invention determines the vertex direction Dt according to the medium difference between the acoustic lens 16 and its environment, meaning that the vertex direction Dt can correspond to the medium difference between the acoustic lens 16 and its adjacent elements. The aforementioned adjacent elements may be the air surrounding the acoustic lens 16 or the target object that the ultrasonic transducer 10 intends to measure; the variation depends on design requirements.

[0011] Please refer to Figure 3, which is a simplified structural diagram of the acoustic lens 16A according to the second embodiment of the present invention. The plurality of sheet-like structures 18 of the acoustic lens 16A can be further divided into a first group G1 and a second group G2; the first group G1 can be located in the central region 22 of the acoustic lens 16A, and the second group G2 is located in the peripheral region 24 of the acoustic lens 16A to surround the first group G1 in the central region 22. The structural height H1 of the plurality of sheet-like structures 18 in the first group G1 is greater than the structural height H2 of the plurality of sheet-like structures 18 in the second group G2, thereby forming an acoustic lens 16A that is convex inward and concave in outward.

[0012] In the second embodiment, the structural height H2 of the plurality of sheet structures 18 of the second group G2 (e.g., the distance of the top end T2 of each sheet structure 18 relative to the reference plane R of the acoustic lens 16) can be selectively designed as the sum of the substrate thickness W and one-quarter of the applied wavelength; wherein, the distance D2 of the turning point P2 of the adjacent sheet structures 18 of the second group G2 relative to the reference plane R of the acoustic lens 16 can be selectively designed as the sum of an integer multiple of half of the applied wavelength and one-eighth of the applied wavelength, that is, the distance D2 is equivalent to the substrate thickness W of the first embodiment.

[0013] Accordingly, the distance D1 of the inflection point P1 of the adjacent sheet structures 18 of the first group G1 relative to the reference plane R of the acoustic lens 16 is the sum of the substrate thickness W and an integer multiple of half the applied wavelength; the distance T1 of the top end T1 of each sheet structure 18 of the first group G1 relative to the reference plane of the acoustic lens 16 (i.e., the structural height H1) is the sum of the distance D1 of the inflection point P1 relative to the reference plane R and one-quarter of the applied wavelength. It is worth mentioning that the calculation relationship of distance D2 (substrate thickness W), structural height H2, distance D1, and structural height H1 relative to the applied wavelength is not limited to the above embodiment and may have an allowable error of 10% to 15% depending on the circumstances.

[0014] Please refer to Figure 4, which is a simplified structural diagram of the acoustic lens 16B according to the third embodiment of the present invention. The plurality of sheet-like structures 18 of the acoustic lens 16B can be further divided into a first group G1 and a second group G2; the first group G1 can be located in the central region 22 of the acoustic lens 16B, while the second group G2 is located in the peripheral region 24 of the acoustic lens 16B, surrounding the first group G1 in the central region 22. In the third embodiment, the structural height H1' of the plurality of sheet-like structures 18 in the first group G1 is smaller than the structural height H2' of the plurality of sheet-like structures 18 in the second group G2, thereby forming a concave-convex acoustic lens 16B.

[0015] In the third embodiment, the structural height H1' of the plurality of sheet structures 18 of the first group G1 (e.g., the distance of the top end T1' of each sheet structure 18 relative to the reference plane R of the acoustic lens 16) can be selectively designed as the sum of the substrate thickness W and one-quarter of the applied wavelength; wherein, the distance D1' of the turning point P1' of the adjacent sheet structures 18 of the first group G1 relative to the reference plane R of the acoustic lens 16 can be selectively designed as the sum of an integer multiple of half of the applied wavelength and one-eighth of the applied wavelength, that is, the distance D1' is equivalent to the substrate thickness W of the first embodiment.

[0016] Accordingly, the distance D2' of the inflection point P2' of the adjacent sheet structures 18 of the second group G2 relative to the reference plane R of the acoustic lens 16 is the sum of the substrate thickness W and an integer multiple of half the applied wavelength; the distance T2' of the top end T2' of each sheet structure 18 of the second group G2 relative to the reference plane of the acoustic lens 16 (i.e., the structural height H2') is the sum of the distance D2' of the inflection point P2' relative to the reference plane R and one-quarter of the applied wavelength. It should be noted that the calculation methods of the distance D1' (substrate thickness W), structural height H1', ​​distance D2', and structural height H2' relative to the applied wavelength are not limited to the above embodiment and may have an allowable error of 10% to 15% depending on the circumstances.

[0017] Please refer to Figures 5 to 7, which are simplified structural diagrams of the acoustic lens 16C according to different embodiments of the present invention. The plurality of sheet-like structures 18 of the acoustic lens 16C can be further divided into a first group G1, a second group G2, and a third group G3. The first group G1 is located in the central region of the acoustic lens 16C, and the second group G2 is located between the first group G1 and the third group G3. As shown in Figure 5, the structural height of the first group G1 is greater than the structural height of the second group G2, and the structural height of the second group G2 is greater than the structural height of the third group G3; as shown in Figure 6, the structural height of the first group G1 is greater than the structural height of the second group G2, and the structural height of the second group G2 is less than the structural height of the third group G3; as shown in Figure 7, the structural height of the first group G1 is less than the structural height of the second group G2, and the structural height of the second group G2 is less than the structural height of the third group G3. Figures 5 through 7 show that the plurality of sheet-like structures 18 can be divided into three or more groups, and these groups may have two or more structural heights; the actual variation depends on the design requirements, and the structural details are not described in detail here.

[0018] In summary, the ultrasonic transducer of the present invention can significantly shorten the film thickness of the acoustic lens without changing its radius of curvature. This allows the protrusion height of each sheet-like structure of the acoustic lens relative to the substrate to be far from the sum of an integer multiple of the application wavelength and one-eighth of the application wavelength. In other words, the predetermined difference between the structure height of the sheet-like structure and the thickness of the substrate can reach a value greater than zero and less than or equal to one-quarter of the application wavelength. This has the advantages of increasing overall signal strength and reducing sidelobe effects, thereby effectively improving the signal-to-noise ratio of the ultrasonic transducer. The above description is only a preferred embodiment of the present invention. All equivalent variations and modifications made within the scope of the claims of this invention should be considered within the scope of this invention. [Simplified Explanation of the Diagram]

[0019] Figure 1 is a schematic diagram of the structure of an ultrasonic transducer according to an embodiment of the present invention. Figure 2 is a simplified structural diagram of an acoustic lens according to the first embodiment of the present invention. Figure 3 is a simplified structural diagram of an acoustic lens according to the second embodiment of the present invention. Figure 4 is a simplified structural diagram of an acoustic lens according to the third embodiment of the present invention. Figures 5 to 7 are simplified structural diagrams of acoustic lenses according to different embodiments of the present invention.

Claims

1. An ultrasonic transducer capable of improving signal-to-noise ratio, comprising: a damping layer; a transducer module disposed in the damping layer; and an acoustic lens disposed on one side of the transducer module opposite to the damping layer, the acoustic lens having a plurality of sheet-like structures with the same curvature, wherein the structural height of each of the plurality of sheet-like structures is defined as having a predetermined difference relative to the thickness of a substrate; wherein, The thickness of the substrate is the sum of an integer multiple of half the wavelength of one of the ultrasonic transducers and one-eighth of the wavelength of the applied wave; wherein the predetermined difference is a numerical range greater than zero and less than or equal to one-quarter of the wavelength of the applied wave.

2. The ultrasonic transducer as claimed in claim 1, wherein the plurality of sheet structures have the same height.

3. The ultrasonic transducer as claimed in claim 2, wherein the height of the structure is the sum of the thickness of the substrate and one-quarter of the applied wavelength.

4. The ultrasonic transducer as claimed in claim 1, wherein the plurality of sheet structures are divided into a first group and a second group, the first group being located in a central region of one of the acoustic lenses and the second group being located in a peripheral region of one of the acoustic lenses to surround the central region.

5. The ultrasonic transducer as claimed in claim 4, wherein the height of the plurality of sheet structures in the first group is greater than the height of the plurality of sheet structures in the second group.

6. The ultrasonic transducer as claimed in claim 5, wherein the structural height of each sheet structure in the second group is the sum of the substrate thickness and one-quarter of the applied wavelength; the distance between a turning point of an adjacent sheet structure in the first group and a reference plane of the acoustic lens is the sum of an integer multiple of the substrate thickness and one-half of the applied wavelength; and the distance between a top end of each sheet structure in the first group and the reference plane is the sum of the distance between the turning point and the reference plane and one-quarter of the applied wavelength.

7. The ultrasonic transducer as claimed in claim 4, wherein the height of the plurality of sheet structures in the first group is less than the height of the plurality of sheet structures in the second group.

8. The ultrasonic transducer as claimed in claim 7, wherein the structural height of each sheet structure in the first group is the sum of the substrate thickness and one-quarter of the applied wavelength; a distance between a turning point of each sheet structure in the second group and a reference plane of the acoustic lens is the sum of an integer multiple of the substrate thickness and one-half of the applied wavelength; and a distance between a top end of an adjacent sheet structure in the second group and the reference plane is the sum of the distance between the turning point and the reference plane and one-quarter of the applied wavelength.

9. The ultrasonic transducer as claimed in claim 1, wherein the plurality of sheet structures are further divided into a first group, a second group and a third group, the first group being located in the central region of one of the acoustic lenses, the second group being located between the first group and the third group, and the first group, the second group and the third group having at least two structural heights.

10. The ultrasonic transducer as claimed in claim 1, wherein the apex orientation of the plurality of sheet structures corresponds to the medium difference between the acoustic lens and one of its adjacent elements.

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