Acoustic lens, method for manufacturing the same, ultrasonic probe, and ultrasonic diagnostic apparatus

Abstract

The present application provides an acoustic lens for an ultrasonic probe, a method for manufacturing the same, and an ultrasonic probe and an ultrasonic diagnostic apparatus each having the acoustic lens, which has a small sound attenuation and a sound impedance suitable for the ultrasonic probe. The acoustic lens for the ultrasonic probe is characterized in that a concave lens portion and a convex lens portion are joined to form the acoustic lens, the propagation speed of ultrasonic waves in the convex lens portion is slower than that in the concave lens portion, the sound impedance of the lens portion for a subject side in the concave lens portion and the convex lens portion is in a range of 1.3 to 1.8 MRayl, and the materials of the concave lens portion and the convex lens portion are both thermoplastic resins.

Description

Technical Field

[0001] This invention relates to acoustic lenses, methods for manufacturing them, ultrasonic probes, and ultrasonic diagnostic devices.

[0002] More specifically, this involves acoustic lenses that minimize sound attenuation and have acoustic impedance suitable for ultrasonic probes. Background Technology

[0003] In the past, acoustic lenses were used in ultrasonic probes of ultrasonic diagnostic devices to improve the resolution of the obtained images.

[0004] An acoustic lens is a medium used to converge or diverge sound waves. By appropriately adjusting the difference between the speed of sound propagation (hereinafter also called the velocity of sound) within the acoustic lens and the velocity of sound in the surrounding material, as well as the shape of the lens, sound waves can be converged or diverged. In ultrasonic probes, acoustic lenses are used to converge ultrasonic waves in the slice direction.

[0005] Regarding the acoustic lens used in ultrasonic probes, in order to reduce the reflection of ultrasonic waves between the probe and the object being tested after satisfying the conditions for ultrasonic wave convergence (sound velocity, lens shape), it is required to be close to the acoustic impedance of the object being tested. Furthermore, in order to improve sensitivity, the sound attenuation (sound propagation attenuation) is required to be small.

[0006] As a prior art, there are convex acoustic lenses that use microparticle-filled silicone rubber in the material (Patent Document 1). Microparticle-filled silicone rubber is excellent as a material for convex acoustic lenses because silicone rubber has a suitable sound velocity and the acoustic impedance can be adjusted by filling it with microparticles such as silica. However, it has the disadvantage of large sound attenuation due to the influence of microparticles.

[0007] To suppress such sound attenuation, a composite acoustic lens with a high-speed concave lens combined with a convex lens portion using silicone rubber was disclosed (Patent Document 2), thereby reducing the overall thickness, and a composite acoustic lens without using microparticles to fill silicone rubber was disclosed (Patent Document 3).

[0008] However, in the case of composite acoustic lenses using the above-mentioned technology, the use of thermosetting resin in the material of at least one lens portion results in poor bonding between the lens portions, making actual manufacturing very difficult. Therefore, there is a need to develop acoustic lenses using materials with good bonding properties.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 58-216294

[0012] Patent Document 2: Japanese Patent Publication No. 7-63465

[0013] Patent Document 3: Japanese Patent Publication No. 2019-504547 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] The present invention was made in view of the above-mentioned problems and conditions, and its solution is to provide an acoustic lens with low sound attenuation and acoustic impedance suitable for an ultrasonic probe, a method for manufacturing the same, and an ultrasonic probe and an ultrasonic diagnostic device equipped with the acoustic lens.

[0016] Methods for solving problems

[0017] In order to solve the above-mentioned problems, the inventors conducted research on the causes of the above-mentioned problems and found that: in an acoustic lens formed by joining a concave lens portion and a convex lens portion, by using a thermoplastic resin in the material of any lens portion, it is possible to provide an acoustic lens with low sound attenuation and acoustic impedance suitable for an ultrasonic probe, thus achieving the present invention.

[0018] That is, the aforementioned problems involved in this invention are solved by the following means.

[0019] 1. An acoustic lens, which is an acoustic lens used in an ultrasonic probe, characterized in that,

[0020] It is constructed by joining a concave lens portion and a convex lens portion.

[0021] The propagation speed of ultrasonic waves in the convex lens portion is slower than that in the concave lens portion.

[0022] The acoustic impedance of the lens portion used on the object side of the concave lens portion and the convex lens portion described above is in the range of 1.3 to 1.8 MRayl, and

[0023] Both the concave lens portion and the convex lens portion are made of thermoplastic resin.

[0024] 2. The acoustic lens according to claim 1, characterized in that the lens surface opposite to the object being tested when disposed in an ultrasonic probe is planar or convex.

[0025] 3. The acoustic lens according to claim 1 or 2, characterized in that the propagation speed of the ultrasonic wave in the convex lens portion is at least 300 m / s slower than the propagation speed of the ultrasonic wave in the concave lens portion.

[0026] 4. The acoustic lens according to any one of claims 1 to 3, characterized in that the thermoplastic resin used as the material for the concave lens portion is a thermoplastic hard resin, and

[0027] The thermoplastic resin used as the material for the aforementioned convex lens portion is a thermoplastic elastomer.

[0028] 5. The acoustic lens according to any one of claims 1 to 4, characterized in that the thermoplastic resin, which is the material of the convex lens portion, has a resilience of 60% or more.

[0029] 6. The acoustic lens according to any one of claims 1 to 5, characterized in that the difference in solubility parameters between at least one component of the material of the concave lens portion and at least one component of the material of the convex lens portion is 1 (cal / cm²). 3 ) 1 / 2 the following.

[0030] 7. The acoustic lens according to any one of claims 1 to 6, characterized in that the concave lens portion and the convex lens portion are fused together to form the lens.

[0031] 8. The acoustic lens according to any one of claims 1 to 7, characterized in that it is configured such that the concave lens portion is on the side of the object being detected and the convex lens portion is on the side of the ultrasonic transducer.

[0032] The thermoplastic resin used as the material for the concave lens portion is a polyolefin-based thermoplastic hard resin, and

[0033] The thermoplastic resin used as the material for the aforementioned convex lens portion is a thermoplastic elastomer containing a polyolefin-based resin component.

[0034] 9. The acoustic lens according to any one of claims 1 to 7, characterized in that it is configured such that the concave lens portion is on the ultrasonic transducer side and the convex lens portion is on the object being detected side.

[0035] The thermoplastic resin used as the material for the concave lens portion is any one of the following thermoplastic rigid resins: polycarbonate, ABS, polybutylene terephthalate, and polyamide.

[0036] The thermoplastic resin used as the material for the aforementioned convex lens portion is a thermoplastic elastomer containing at least one of polyester, polyamide, and polyurethane resin components.

[0037] 10. A method for manufacturing an acoustic lens, comprising a method for manufacturing an acoustic lens according to any one of items 1 to 9, characterized in that,

[0038] The concave lens portion and the convex lens portion are fused together.

[0039] 11. The method for manufacturing an acoustic lens according to claim 10, characterized in that the concave lens portion and the convex lens portion are fused together by insert molding.

[0040] 12. The method for manufacturing an acoustic lens according to claim 10, characterized in that the concave lens portion and the convex lens portion are fused together by two-color molding.

[0041] 13. An ultrasonic probe comprising an ultrasonic transducer that transmits ultrasonic waves to a test object and receives its reflected echoes, and an acoustic lens disposed on the transceiver wavefront side of the ultrasonic transducer, characterized in that,

[0042] The aforementioned acoustic lens is any one of items 1 to 9.

[0043] 14. An ultrasonic diagnostic apparatus, characterized in that it comprises the ultrasonic probe described in item 13.

[0044] The effects of the invention

[0045] Through the above-described means of the present invention, it is possible to provide an acoustic lens with low sound attenuation and acoustic impedance suitable for an ultrasonic probe, a method for manufacturing the same, and an ultrasonic probe and ultrasonic diagnostic device equipped with the acoustic lens.

[0046] The mechanism by which the effects of this invention are manifested or function is not yet clear, but speculation is offered below.

[0047] In the past, in order to form a convex lens shape that is close to the acoustic impedance of the object being tested (within the range of 1.3 to 1.8 M ayl), silicone rubber filled with microparticles that have high sound attenuation was used. However, in the acoustic lens of the present invention, the necessary shape conditions are met by combining a concave lens part with high sound speed and a convex lens part with low sound speed, and the necessary acoustic impedance conditions are met by using a lens on the side of the object being tested. Thus, it can be made without microparticles, and it is effective in attenuating sound.

[0048] Furthermore, a key feature of the present invention is that each lens portion is made of thermoplastic resin. This allows for easy joining of the lens portions, enabling the provision of an acoustic lens that satisfies the aforementioned conditions, such as the speed of sound, after considering the joinability.

[0049] It is believed that through these manifestation or action mechanisms, acoustic lenses with low sound attenuation and acoustic impedance suitable for ultrasonic probes can be provided. Attached Figure Description

[0050] Figure 1 This is a cross-sectional view of an acoustic lens configured such that the concave lens portion is on the side of the object being tested and the convex lens portion is on the side of the ultrasonic transducer.

[0051] Figure 2 This is a cross-sectional view of an acoustic lens configured such that the concave lens portion is on the side of the ultrasonic transducer and the convex lens portion is on the side of the object being tested.

[0052] Figure 3 A graph showing the relationship between the resilience and sound attenuation rate in thermoplastic elastomers.

[0053] Figure 4 This is a schematic cross-sectional view of an ultrasonic probe.

[0054] Figure 5 This is a schematic diagram of an ultrasound diagnostic device. Detailed Implementation

[0055] The acoustic lens of the present invention is an acoustic lens for an ultrasonic probe, characterized in that it is formed by joining a concave lens portion and a convex lens portion, wherein the propagation speed of the ultrasonic wave in the convex lens portion is slower than the propagation speed of the ultrasonic wave in the concave lens portion, the acoustic impedance of the lens portion used on the object side of the concave lens portion and the convex lens portion is in the range of 1.3 to 1.8 MRayl, and the material of the concave lens portion and the convex lens portion is thermoplastic resin.

[0056] This feature is a common or corresponding technical feature of the following embodiments.

[0057] Regarding the acoustic lens of the present invention, in terms of achieving good sealing with the object being tested, preventing air entrapment, and obtaining good tomographic images, it is preferable that the lens surface facing the object being tested when disposed in an ultrasonic probe is planar or convex.

[0058] Regarding the acoustic lens of the present invention, in terms of reducing sound attenuation by reducing the thickness of the lens through reducing curvature and in terms of suppressing the shapeability of the thickness deviation, it is preferable that the propagation speed of the ultrasonic wave in the convex lens portion is 300 m / s or more slower than the propagation speed of the ultrasonic wave in the concave lens portion.

[0059] Regarding the acoustic lens of the present invention, considering the propagation speed of ultrasonic waves, it is preferable that the thermoplastic resin used as the material of the concave lens portion is a thermoplastic hard resin, and that the thermoplastic resin used as the material of the convex lens portion is a thermoplastic elastomer.

[0060] Regarding the acoustic lens of the present invention, in terms of reducing sound attenuation caused by the material properties of the convex lens portion, it is preferable that the thermoplastic resin used as the material of the convex lens portion has a resilience of 60% or more.

[0061] Regarding the acoustic lens of the present invention, in terms of adhesion, it is preferable that the difference in solubility parameters between at least one of the components contained in the material of the concave lens portion and at least one of the components contained in the material of the convex lens portion is 1 (cal / cm²). 3 ) 1 / 2 the following.

[0062] Regarding the acoustic lens of the present invention, in terms of the absence of sound attenuation caused by the adhesive layer, it is preferable to form a structure by fusion bonding the concave lens portion and the convex lens portion.

[0063] Regarding the acoustic lens of the present invention, in terms of satisfying the conditions of acoustic impedance and ultrasonic wave propagation speed while having good adhesion, it is preferable to construct the concave lens portion as the object being detected and the convex lens portion as the ultrasonic transducer side. The thermoplastic resin used as the material of the concave lens portion is a polyolefin-based thermoplastic hard resin, and the thermoplastic resin used as the material of the convex lens portion is a thermoplastic elastomer containing a polyolefin-based resin component.

[0064] Regarding the acoustic lens of the present invention, in terms of satisfying the conditions of acoustic impedance and ultrasonic wave propagation speed while maintaining good adhesion, it is preferable to configure the concave lens portion as the ultrasonic transducer side and the convex lens portion as the object being detected side. The thermoplastic resin used as the material of the concave lens portion is a thermoplastic rigid resin selected from polycarbonate, ABS, polybutylene terephthalate, and polyamide, and the thermoplastic resin used as the material of the convex lens portion is a thermoplastic elastomer containing at least one of polyester, polyamide, and polyurethane resin components.

[0065] The method for manufacturing an acoustic lens of the present invention is a method for manufacturing an acoustic lens of the acoustic lens described in the present invention, characterized in that the concave lens portion and the convex lens portion are fused together.

[0066] Regarding the manufacturing method of the acoustic lens of the present invention, in terms of being able to melt-joint without using a special molding machine, it is preferable to use insert molding to melt-joint the concave lens portion and the convex lens portion.

[0067] Regarding the manufacturing method of the acoustic lens of the present invention, in terms of enabling the molding and joining of the first lens portion to be completed in a single process, it is preferable to melt-join the concave lens portion and the convex lens portion by two-color molding.

[0068] The ultrasonic probe of the present invention comprises an ultrasonic transducer that transmits ultrasonic waves to a test object and receives its reflected echoes, and an acoustic lens disposed on the transceiver wavefront side of the ultrasonic transducer, wherein the acoustic lens is the acoustic lens of the present invention.

[0069] The ultrasonic diagnostic device of the present invention is characterized by comprising the ultrasonic probe of the present invention.

[0070] The present invention, its constituent elements, and the forms and methods for carrying out the invention will be described in detail below. It should be noted that in this application, "~" is used to indicate the lower and upper limits of the numerical values ​​included before and after it.

[0071] (1) Summary of the acoustic lens of the present invention

[0072] The acoustic lens of the present invention is an acoustic lens for an ultrasonic probe, characterized in that it is formed by joining a concave lens portion and a convex lens portion, wherein the propagation speed of the ultrasonic wave in the convex lens portion is slower than the propagation speed of the ultrasonic wave in the concave lens portion, the acoustic impedance of the lens portion used on the subject side of the concave lens portion and the convex lens portion is in the range of 1.3 to 1.8 MRayl, and both the concave lens portion and the convex lens portion are made of thermoplastic resin.

[0073] By possessing these characteristics, it is possible to meet the conditions for ultrasonic wave convergence (sound velocity, lens shape), and to simultaneously achieve both acoustic impedance adjustment and sound attenuation suppression. Furthermore, in terms of manufacturing, it is practically possible to provide a product that considers fitability.

[0074] The following details the situation.

[0075] (2) Shape of the acoustic lens

[0076] The acoustic lens of the present invention is characterized by being constructed by joining a concave lens portion and a convex lens portion.

[0077] The cross-sectional shape of a concave lens portion is such that the thickness of the central portion is thinner than the thickness of the peripheral portion (so-called concave shape). Conversely, the cross-sectional shape of a convex lens portion is such that the thickness of the central portion is thicker than the thickness of the peripheral portion (so-called convex shape).

[0078] With regard to the acoustic lens of the present invention, in the ultrasonic probe, it includes, as Figure 1 The acoustic lens 26 shown is configured such that the concave lens portion 31 is on the side of the object being detected (right side of the figure) and the convex lens portion 32 is on the side of the ultrasonic transducer (left side of the figure); and as shown in the figure... Figure 2 The acoustic lens 26 shown is configured such that the concave lens portion 31 is the ultrasonic transducer side (left side of the figure) and the convex lens portion 32 is the object being detected side (right side of the figure).

[0079] exist Figure 1 and Figure 2 In the image, the arrows indicate how the ultrasonic waves emitted from the ultrasonic transducer side are refracted by the acoustic lens and converge on the side of the object being tested.

[0080] There are no particular limitations on the thickness and curvature of each lens part, and it can be designed according to the application. From the point of view of sound attenuation, it is preferable that each lens part is thin.

[0081] Regarding the acoustic lens of the present invention, when disposed in an ultrasonic probe, it is preferable that the lens surface facing the object being tested is planar or convex. This ensures good adhesion to the object being tested, prevents air entrapment, and allows for the acquisition of a good tomographic image.

[0082] (3) Thermoplastic resin

[0083] The acoustic lens of the present invention is characterized in that both the concave lens portion and the convex lens portion are made of thermoplastic resin. Therefore, the lens portions can be easily joined together by melt bonding and adhesion using an adhesive.

[0084] The term "thermoplastic resin" refers to a resin that exhibits thermoplastic properties. Furthermore, in this invention, resins that do not exhibit rubber elasticity are called rigid resins, and resins that exhibit rubber elasticity are called elastomers. That is, thermoplastic resins include both rigid thermoplastic resins and thermoplastic elastomers.

[0085] It should be noted that the material of each lens part can be mainly composed of thermoplastic resin, and other additives may be contained in small amounts within the range that does not impair thermoplasticity.

[0086] Elastomers consist of soft segments, which impart elasticity, and hard segments, which, while flowing at high temperatures, prevent deformation at room temperatures. The soft and hard segments can be chemically bonded block copolymers or simply mixed polymer alloys without chemical bonding.

[0087] When the elastomer is a polymer alloy type, a block copolymer elastomer can be used as the soft segment.

[0088] Thermoplastic rigid resins include, for example, polyolefin-based, polycarbonate-based, ABS (acrylonitrile-butadiene-styrene)-based, polybutylene terephthalate-based, and polyamide-based thermoplastic rigid resins.

[0089] Specific examples of thermoplastic rigid resins include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, crystalline propylene homopolymer, crystalline ethylene-propylene copolymer, olefin resins such as polymethylpentene, acrylic acid-styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, methacrylic acid-styrene copolymer, nylon resin, butylene terephthalate resin, ethylene terephthalate resin, styrene resin, styrene-acrylonitrile copolymer, and carbonate resins.

[0090] Thermoplastic elastomers include, for example, thermoplastic elastomers containing resin components such as polyolefins, polyesters, polyamides, and polyurethanes as soft or hard segments.

[0091] Specific examples of thermoplastic elastomers include ester-based elastomers, olefin-based elastomers, amide-based elastomers, urethane-based elastomers, styrene-based elastomers, and acrylic elastomers.

[0092] (4) Solubility parameter (SP value)

[0093] Regarding the bonding properties, the acoustic lens of the present invention preferably has a solubility parameter difference of at least one component of the material of the concave lens portion and at least one component of the material of the convex lens portion of 1 (cal / cm²). 3 ) 1 / 2 the following.

[0094] Solubility parameters, also known as SP values, are values ​​that can be used as indicators of the solubility and compatibility of solvents and resins. If the difference in solubility parameters is small, the solubility and compatibility are good, and therefore the bonding between thermoplastic resins is good.

[0095] When the material of the lens portion is a hard resin, the term "at least one of the components contained in the material" refers to that hard resin when the material of the lens portion is composed of a single hard resin, and to at least any one of the hard resins when it is composed of multiple hard resins.

[0096] When the lens material is an elastomer, "at least one of the components contained in the material" refers to at least one of the components contained in the elastomer, namely, soft segments and hard segments. Furthermore, when there are multiple soft segments or hard segments, it refers to at least one of the multiple segments.

[0097] (5)joint

[0098] The concave and convex lens portions of the present invention use thermoplastic resin in any material, so the lens portions can be easily joined together by melt bonding or by using adhesive bonding.

[0099] (5.1) Fusion bonding

[0100] In terms of productivity, fusion bonding is preferred. Furthermore, since an adhesive layer consisting of adhesive and primer is not required, it is preferable to avoid the attenuation of sound caused by the adhesive layer.

[0101] As a molding method for performing melt bonding, insert molding or two-color molding is preferred.

[0102] In insert molding, a pre-molded lens portion can be inserted into a mold, and resin material for another lens portion can be injected into the space within the mold to achieve fusion bonding. Insert molding is preferred in terms of the ability to achieve fusion bonding without the use of a special molding machine.

[0103] In two-color molding, after the material of one lens portion is injected into the mold and filled, the material of the other lens portion is filled into the mold and fused together. Two-color molding is preferred in that it allows for the molding and joining of the first lens portion to be carried out in a single process.

[0104] In two-color molding, there are rotation methods, flexible back-back methods, etc., and the acoustic lens of the present invention can be molded using all of these methods.

[0105] (5.2) Bonding using adhesives

[0106] The concave lens portion and convex lens portion of the present invention can also be joined by an adhesive. Regarding the joining using an adhesive, it is preferable that as long as each lens portion is molded, they can be integrated even without a molding machine for fusion bonding.

[0107] There are no particular restrictions on the type of adhesive; any general adhesive can be used as an adhesive that can bond thermoplastic resins together.

[0108] Furthermore, regarding adhesion, it is preferable to apply a primer before bonding with an adhesive. A primer is an adhesive aid used in the pretreatment process before applying the adhesive. By using a primer suitable for the objects being bonded and the type of adhesive, adhesion can be improved.

[0109] It should be noted that, considering the impact of the adhesive layer on sound attenuation and productivity, melt bonding is preferred over bonding using adhesives.

[0110] (6) Comparison of bonding properties

[0111] To compare bonding properties, as an example, the evaluation results of the bonding properties of various thermoplastic elastomers and thermosetting elastomers (silicone rubber) for thermoplastic rigid resins are shown in Table I.

[0112] In addition, details of the materials used for the bonding evaluation are shown in Table II.

[0113]

[0114]

[0115] The "Bonding with TPX" column in Table I describes the evaluation when polymethylpentene (TPX) was used in the second layer sheet. The "Bonding with PC" column describes the evaluation when polycarbonate (PC) was used.

[0116] Table II's "SP Value" column lists the solubility parameters of components that contribute to melt bonding in the case of thermoplastic resins. In the case of silicone rubber, only the material's own solubility parameters are listed.

[0117] The bonding performance was evaluated as follows. It should be noted that an injection molding machine (Sumitomo Heavy Industries, Ltd. SE-50DU) was used in the production of the evaluation sheet. Furthermore, the resin melt temperature and mold temperature during the production of the evaluation sheet were set to the temperatures recommended by the respective resin material manufacturers.

[0118] [Preparation of composite sheets for evaluating fusion bonding]

[0119] After injecting molten resin, which is the material for the first layer of sheet material, into a mold with a length of 35mm, a width of 35mm, and a thickness of 1mm, the material is cooled and solidified to produce the first layer of sheet material.

[0120] The 1mm thick first layer sheet was placed in a mold measuring 35mm x 35mm x 2mm. Molten resin, which would become the material for the second layer sheet, was injected into the space within the mold and then cooled to solidify, thereby producing a composite sheet for evaluation of fusion bonding.

[0121] [Evaluation of bonding using adhesives in the fabrication of composite sheets]

[0122] After injecting molten resin into a mold measuring 35mm in length, 35mm in width, and 1mm in thickness, the resin is cooled and allowed to solidify, thereby producing the first layer sheet and the second layer sheet respectively.

[0123] The first and second layers of the sheet were bonded together using an adhesive with cyanoacrylate as the main component (PPX Set manufactured by Semedai Co., Ltd.), and a composite sheet for evaluating the bonding using the adhesive was produced.

[0124] [Evaluation of the bonding using adhesive and primer in the fabrication of composite sheets]

[0125] After injecting molten resin into a mold measuring 35mm in length, 35mm in width, and 1mm in thickness, the resin is cooled and allowed to solidify, thereby producing the first layer sheet and the second layer sheet respectively.

[0126] The first and second layers of the sheet fabricated above were coated with a primer (PPX Set manufactured by Semidine Co., Ltd.) with n-heptane as the main component. The first and second layers of the sheet coated with the primer were then bonded together with an adhesive (PPX Set manufactured by Semidine Co., Ltd.) with cyanoacrylate as the main component, thus creating a composite sheet for evaluation using the adhesive and primer bonding method.

[0127] [Fabrication of a sheet with silicone rubber as the first layer of material]

[0128] In the fabrication of the aforementioned composite sheet, the first layer, made of silicone rubber, was prepared by mixing 0.5 parts by mass of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (as a vulcanizing agent) with 100 parts by mass of dimethylpolysiloxane (Shin-Etsu Chemical Industry Co., Ltd., KE742), followed by addition molding at 165°C for 10 minutes, and then secondary vulcanization at 200°C for 2 hours. The sheet was molded to a thickness of 1 mm.

[0129] [Evaluation of Adhesion]

[0130] The bonding properties of the composite sheets prepared above were evaluated as described below and are recorded in Table I.

[0131] ○: It can be joined together and will not peel off even when stretched by hand.

[0132] △: It can be joined, but it will peel off if stretched by hand.

[0133] ×: Cannot be joined.

[0134] As shown in Table I, the bonding properties between thermoplastic resins are better than those between silicone rubber and thermoplastic resins. In the case of silicone rubber and thermoplastic resins, bonding is impossible with just an adhesive; in contrast, between thermoplastic resins, bonding is possible with just an adhesive by appropriately combining the materials. Furthermore, in the case of silicone rubber and thermoplastic resins, even when using a primer with an adhesive, peeling occurs when stretched by hand; in contrast, bonding is good between thermoplastic resins. Moreover, in the case of silicone rubber and thermoplastic resins, fusion bonding is impossible; in contrast, between thermoplastic resins, fusion bonding is possible by appropriately combining the materials.

[0135] (7) The speed of propagation of ultrasound

[0136] The acoustic lens of the present invention is characterized in that the propagation speed of ultrasonic waves in the convex lens portion is slower than the propagation speed of ultrasonic waves in the concave lens portion. This is because it causes the ultrasonic waves to converge.

[0137] The greater the difference in the propagation speed of the ultrasonic waves in the convex lens portion and the concave lens portion, the better; preferably, it is 300 m / s or more. A greater difference in the propagation speed of the ultrasonic waves in the convex lens portion and the concave lens portion results in a higher refraction angle of the ultrasonic waves at the joint surface, making it easier to collect sound due to the reduced curvature. Furthermore, by reducing the curvature, the thickness of the lens can be reduced. Reducing the lens thickness reduces sound attenuation.

[0138] The relationship between the propagation speed of the ultrasonic waves in the concave lens section and the convex lens section and the propagation speed of the ultrasonic waves in the object being tested can be appropriately adjusted and is not particularly limited. Since it is necessary to converge the ultrasonic waves, the propagation speed of the ultrasonic waves in the concave lens section needs to be faster than the propagation speed of the ultrasonic waves in the object being tested.

[0139] In practical terms, it is preferable that the propagation speed of ultrasound in the concave lens portion is faster than that of ultrasound in a living organism, and therefore preferably 1530 m / s or higher.

[0140] Furthermore, considering the propagation speed of ultrasound, it is preferable to use a thermoplastic rigid resin for the concave lens portion and a thermoplastic elastomer for the convex lens portion.

[0141] (8) Acoustic impedance

[0142] The acoustic lens of the present invention is characterized in that the acoustic impedance of the lens portion used on the subject side of the concave lens portion and the convex lens portion is in the range of 1.3 to 1.8 MTayl. This reduces the reflection of ultrasonic waves between the acoustic lens and the subject.

[0143] In addition, in terms of reducing the reflection of ultrasonic waves between the lens portions, it is preferable that the difference in acoustic impedance between the lens portion used on the body being tested and the lens portion used on the ultrasonic transducer side is 0.6 MRayl or less.

[0144] Acoustic impedance is defined by the formula: Acoustic impedance Z[MRayl] = density ρ[kg / m³]. 3 The formula representing the speed of sound C [m / s] is an intrinsic constant of a substance. The unit is generally [MRayl], 1 [MRayl] = 1.0 × 10⁻⁶ m / s. 6 [kg·m 2 / s].

[0145] (9) Rebound rate

[0146] Regarding the acoustic lens of the present invention, the thermoplastic resin used as the material for the convex lens portion preferably has a resilience of 60% or more. As described above, considering the propagation speed of ultrasound, it is preferable to use a thermoplastic elastomer as the material for the convex lens portion; the higher the resilience of the thermoplastic elastomer, the less the sound tends to be attenuated due to the material properties (see Table III). Figure 3 Therefore, the higher the rebound rate, the less the sound attenuation caused by the material properties of the convex lens will be. Considering practicality, a rebound rate of 60% or higher is preferred.

[0147] (10) Evaluation of sound characteristics

[0148] Examples of materials that can be used in the lens section are shown in Table III. It should be noted that there are no limitations on the materials that can be used in the convex lens section.

[0149]

[0150] The values ​​recorded in Table III are as follows, obtained by preparing the test sheet.

[0151] [Preparation of the sheet for measurement]

[0152] Molten resin, which is the material, is injected into a mold measuring 35mm in length, 35mm in width, and 1mm in thickness. The mold is then cooled and allowed to solidify, thereby producing a sheet for testing.

[0153] It should be noted that an injection molding machine (Sumitomo Heavy Industries, Ltd. SE-50DU) was used in the fabrication of the test sheet. Furthermore, the resin melting temperature and mold temperature during the fabrication of the test sheet were set to the temperatures recommended by the respective resin material manufacturers.

[0154] [density]

[0155] The test was performed at 25°C according to JIS C 2123.

[0156] [Speed ​​of sound (the speed at which ultrasound waves propagate)]

[0157] The velocity was measured at 25°C using a sound velocity measuring device (Ultrasonic Industrial Co., Ltd.: Surround Sound Velocity Measuring Device UVM-2 type) at a measurement frequency of 5MHz.

[0158] [Acoustic impedance]

[0159] Based on the density and sound speed measured above, the acoustic impedance can be calculated using the following formula.

[0160] Z = ρ × C

[0161] Z: Acoustic impedance [MRayl]

[0162] ρ: Density [kg / m³] 3 ]

[0163] C: Speed ​​of sound [m / s]

[0164] [Sound attenuation rate]

[0165] With the test sheet placed in a water tank filled with water at 25°C, a 15MHz ultrasonic wave is generated in the water using an ultrasonic pulse receiver JPR-10C (manufactured by Japan Probe Co., Ltd.). The amplitude of the ultrasonic wave before and after passing through the test sheet is measured. The attenuation rate is calculated from the measured amplitude using the following formula.

[0166] P x =P0e -αx

[0167] P x Amplitude after transmission

[0168] P0: Amplitude before transmission

[0169] e: Natural logarithm

[0170] α: Attenuation rate [dB / mm]

[0171] x: distance [mm]

[0172] (11) Preferred combination of materials

[0173] The preferred combination of materials used in the acoustic lens of the present invention will be described.

[0174] exist Figure 1 In the case of the acoustic lens shown, which is configured such that the concave lens portion is on the side of the object being detected and the convex lens portion is on the side of the ultrasonic transducer, it is preferable that the thermoplastic resin used as the material of the concave lens portion is a polyolefin-based thermoplastic rigid resin, and the thermoplastic resin used as the material of the convex lens portion is a thermoplastic elastomer containing a polyolefin-based resin component.

[0175] This is because, for the material of the lens portion used on the side of the object being detected, an acoustic impedance of 1.3 to 1.8 MNayl is required. In the case of the concave lens portion, a thermoplastic resin is preferred, except for the acoustic impedance. Considering the propagation speed of ultrasound, the material is preferably a polyolefin-based thermoplastic rigid resin. Furthermore, this is because, considering the adhesion to the material of the concave lens portion, the material of the convex lens portion used on the side of the ultrasonic transducer is preferably a thermoplastic elastomer containing a polyolefin-based resin component.

[0176] Figure 2 In the case of the acoustic lens shown, in which the concave lens portion is the ultrasonic transducer side and the convex lens portion is the object being detected side, the thermoplastic resin used as the material of the concave lens portion is preferably a thermoplastic rigid resin selected from polycarbonate, ABS, polybutylene terephthalate, and polyamide, and the thermoplastic resin used as the material of the convex lens portion is a thermoplastic elastomer containing at least one of polyester, polyamide, and polyurethane resin components.

[0177] This is because the material of the lens portion used on the side of the object being detected needs to have an acoustic impedance of 1.3 to 1.8 MNayl. In the case of the convex lens portion, it is preferable to use a thermoplastic resin, except for the acoustic impedance. Considering the propagation speed of ultrasound, the preferred material is a thermoplastic elastomer containing at least one of the resin components of polyester, polyamide, and polyurethane. Furthermore, this is because, considering the adhesion to the material of the convex lens portion, the material of the concave lens portion used on the side of the ultrasonic transducer is preferably a thermoplastic rigid resin of any one of the following: polycarbonate, ABS, polybutylene terephthalate, and polyamide.

[0178] (12) Ultrasonic probe

[0179] The ultrasonic probe of the present invention comprises an ultrasonic transducer that transmits ultrasonic waves to a test object and receives its reflected echoes, and an acoustic lens disposed on the transceiver wavefront side of the ultrasonic transducer, characterized in that the acoustic lens is the acoustic lens of the present invention.

[0180] An ultrasonic transducer is a piezoelectric element that uses piezoelectric materials to convert electrical signals into mechanical vibrations and vice versa. It can receive and transmit ultrasonic waves and exhibits the pyroelectric effect.

[0181] Piezoelectric materials are materials containing piezoelectric elements capable of converting electrical signals into mechanical vibrations and vice versa. Piezoelectric elements that can be used include lead zirconate titanate (PZT) ceramics, piezoelectric ceramics such as lead titanate and lead niobate, piezoelectric single crystals composed of solid solution single crystals such as lithium niobate, lead zinc niobate and lead titanate, lead magnesium niobate and lead titanate, quartz, Rochelle salts, polyvinylidene fluoride (PVDF), or PVDF copolymers such as polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)), polymers of vinylidene cyanide (VDCN) such as polyvinylidene cyanide (PVDCN), or vinylidene cyanide copolymers, or odd-numbered nylons such as nylon 9 and nylon 11, aromatic nylons, alicyclic nylons, or polyhydroxycarboxylic acids such as polylactic acid and polyhydroxybutyrate, cellulose derivatives, polyurea, and other organic polymer piezoelectric materials.

[0182] The thickness of the piezoelectric material is used, for example, in the range of 100 to 500 μm. The ultrasonic transducer is used with I / O (input / output) electrodes and GND (ground) electrodes on both sides.

[0183] There are no particular limitations on the components other than the acoustic lens and the ultrasonic transducer; for example, anything that can make it... Figure 4 The structure shown is as described.

[0184] Figure 4The ultrasonic probe 2 shown includes: a back layer 21, an I / O (input / output) electrode 22 as the first electrode, an ultrasonic transducer (piezoelectric element) 23, a GND (ground) electrode 24 as the second electrode, an acoustic matching layer 25, and an acoustic lens 26.

[0185] (13) Ultrasonic diagnostic device

[0186] The ultrasonic diagnostic device of the present invention is characterized by comprising the ultrasonic probe of the present invention.

[0187] There are no particular limitations on the components other than the ultrasonic probe; for example, anything that enables it to become Figure 5 The structure shown is as described.

[0188] Figure 5 The ultrasonic diagnostic apparatus 100 shown includes an ultrasonic diagnostic apparatus body 1 and an ultrasonic probe 2. The ultrasonic diagnostic apparatus body 1 is connected to the ultrasonic probe 2 via a cable 3. By sending a drive signal of electrical signal to the ultrasonic probe 2, transmitting ultrasonic waves to the object under test is transmitted to the ultrasonic probe 2. At the same time, based on the electrical signal generated by the ultrasonic probe 2 according to the reflected ultrasonic waves from the object under test, i.e., the received signal, the internal state of the object under test is imaged as ultrasonic image data. In addition, the ultrasonic diagnostic apparatus body 1 includes an operation input unit 11 and a display unit 17.

[0189] Industrial availability

[0190] The present invention can utilize an acoustic lens with low sound attenuation and acoustic impedance suitable for an ultrasonic probe, a method for manufacturing the same, and an ultrasonic probe and an ultrasonic diagnostic device equipped with the acoustic lens.

[0191] Explanation of reference numerals in the attached figures

[0192] 1. Main body of the ultrasound diagnostic device

[0193] 2. Ultrasonic probe

[0194] 3 Cables

[0195] 11 Operation Input Section

[0196] 17 Display Section

[0197] 21 Backside layer

[0198] 22 I / O electrodes

[0199] 23. Ultrasonic transducer

[0200] 24 GND electrode

[0201] 25 Sound Matching Layers

[0202] 26 Acoustic Lenses

[0203] 31. Concave lens section

[0204] 32 Convex lens section

[0205] 100 Ultrasonic Diagnostic Device

Claims

1. An acoustic lens, used in an ultrasonic probe, characterized in that, It is constructed by joining a concave lens portion and a convex lens portion. The concave lens portion has a cross-sectional shape in which the thickness of the central portion is thinner than the thickness of the peripheral portion, and the convex lens portion has a cross-sectional shape in which the thickness of the central portion is thicker than the thickness of the peripheral portion. The propagation speed of ultrasonic waves in the convex lens portion is slower than that in the concave lens portion. The acoustic impedance of the concave lens portion and the lens portion used on the subject side of the convex lens portion is in the range of 1.3 to 1.8 MTayl, and Both the concave lens portion and the convex lens portion are made of thermoplastic resin. The thermoplastic resin used as the material for the convex lens portion has a resilience of 60% or more.

2. The acoustic lens according to claim 1, characterized in that, When used with an ultrasonic probe, the lens surface facing the object being tested is either flat or convex.

3. The acoustic lens according to claim 1 or 2, characterized in that, The propagation speed of the ultrasonic wave in the convex lens portion is more than 300 m / s slower than that in the concave lens portion.

4. The acoustic lens according to claim 1 or 2, characterized in that, The thermoplastic resin used as the material for the concave lens portion is a thermoplastic hard resin, and The thermoplastic resin used as the material for the convex lens portion is a thermoplastic elastomer.

5. The acoustic lens according to claim 1 or 2, characterized in that, The difference in solubility parameter between at least one component in the material of the concave lens portion and at least one component in the material of the convex lens portion is 1 (cal / cm²). 3 ) 1 / 2 the following.

6. The acoustic lens according to claim 1 or 2, characterized in that, The concave lens portion and the convex lens portion are formed by fusion bonding.

7. The acoustic lens according to claim 1 or 2, characterized in that, It is configured such that the concave lens portion is on the side of the object being detected and the convex lens portion is on the side of the ultrasonic transducer. The thermoplastic resin used as the material for the concave lens portion is a polyolefin-based thermoplastic hard resin, and The thermoplastic resin used as the material for the convex lens portion is a thermoplastic elastomer containing a polyolefin resin component.

8. The acoustic lens according to claim 1 or 2, characterized in that, The concave lens portion is configured such that the ultrasonic transducer side is the concave lens portion and the object being tested side is the convex lens portion. The thermoplastic resin used as the material for the concave lens portion is any one of the following thermoplastic rigid resins: polycarbonate, ABS, polybutylene terephthalate, and polyamide. The thermoplastic resin used as the material for the convex lens portion is a thermoplastic elastomer containing at least one resin component selected from polyester, polyamide, and polyurethane.

9. A method for manufacturing an acoustic lens, comprising a method for manufacturing an acoustic lens according to any one of claims 1 to 8, characterized in that, The concave lens portion and the convex lens portion are fused together.

10. The method for manufacturing an acoustic lens according to claim 9, characterized in that, The concave lens portion and the convex lens portion are fused together by insert molding.

11. The method for manufacturing an acoustic lens according to claim 9, characterized in that, The concave lens portion and the convex lens portion are fused together by two-color molding.

12. An ultrasonic probe comprising an ultrasonic transducer that transmits ultrasonic waves to a test object and receives its reflected echoes, and an acoustic lens disposed on the transceiver wavefront side of the ultrasonic transducer, characterized in that... The acoustic lens is the acoustic lens according to any one of claims 1 to 8.

13. An ultrasonic diagnostic device, characterized in that, It has the ultrasonic probe as described in claim 12.

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