Acoustic lens, its manufacturing method, ultrasonic probe, and ultrasonic diagnostic device

Abstract

The present invention addresses the problem of providing: an acoustic lens exhibiting low attenuation of sound and having an acoustic impedance appropriate for an ultrasound probe; a method for manufacturing the same; and an ultrasound probe and an ultrasonographic device that are provided with the acoustic lens.　The acoustic lens according to the present invention is for an ultrasound probe, and is configured by joining a concave lens portion and a convex lens portion to each other. This acoustic lens is characterized in that: the propagation velocity of ultrasound in the convex lens portion is lower than the propagation velocity of ultrasound in the concave lens portion; the acoustic impedance of one of the concave lens portion and the convex lens portion for use on an inspection object side falls within a range of 1.3-1.8 MRayl; and the materials of the concave lens portion and the convex lens portion are both thermoplastic resins.

Description

[Technical Field]

[0001] The present invention relates to an acoustic lens, a method for manufacturing the same, an ultrasonic probe, and an ultrasonic diagnostic device. More specifically, the present invention relates to an acoustic lens or the like that has low sound attenuation and acoustic impedance suitable for an ultrasonic probe. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an acoustic lens is used in an ultrasonic probe of an ultrasonic diagnostic apparatus in order to improve the resolution of an obtained image.

[0003] An acoustic lens is a medium for focusing or diverging sound waves. Sound waves can be focused or diverged by appropriately adjusting the difference between the propagation speed of sound waves in the acoustic lens (hereinafter also referred to as the speed of sound) and the speed of sound in the surrounding material, as well as the shape of the lens. Ultrasound probes use acoustic lenses that focus ultrasound waves in the slice direction.

[0004] Acoustic lenses for ultrasound probes must satisfy the conditions for focusing ultrasound (sound speed, lens shape), and must have an acoustic impedance close to that of the object to minimize reflection of ultrasound between the object and the lens.Furthermore, to increase sensitivity, acoustic attenuation (acoustic propagation attenuation) must be small.

[0005] Prior art includes a convex acoustic lens made of microparticle-filled silicone rubber (Patent Document 1). Microparticle-filled silicone rubber is an excellent material for convex acoustic lenses because silicone rubber has an appropriate sound speed and acoustic impedance is adjusted by filling it with silica or other microparticles. However, it has the drawback of causing significant sound attenuation due to the influence of the microparticles.

[0006] In order to suppress such sound attenuation, a composite acoustic lens (Patent Document 2) has been disclosed in which the overall thickness is reduced by combining a convex lens section using silicone rubber with a concave lens section with a high sound velocity, and furthermore, a composite acoustic lens (Patent Document 3) has been disclosed in which no microparticle-filled silicone rubber is used.

[0007] However, because composite acoustic lenses using the above-described technology use a thermosetting resin as the material for at least one of the lens sections, the bonding between the lens sections is poor, making them extremely difficult to manufacture in practice. Therefore, there has been a demand for the development of an acoustic lens using a material with good bonding properties. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 58-216294 [Patent Document 2] Special Publication No. 7-63465 [Patent Document 3] Special Publication No. 2019-504547 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above problems and circumstances, and aims to provide an acoustic lens that has 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 that include the acoustic lens. [Means for solving the problem]

[0010] In order to solve the above problems, the present inventors investigated the causes of the above problems and discovered that, in an acoustic lens formed by bonding a concave lens portion and a convex lens portion, by using a thermoplastic resin as the material for both lens portions, it is possible to provide an acoustic lens or the like that has low sound attenuation and an acoustic impedance that is suitable for an ultrasonic probe, and this led to the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0011] 1. An acoustic lens for an ultrasound probe, comprising: The concave lens portion and the convex lens portion are bonded together. 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, The acoustic impedance of the lens portion of the concave lens portion and the convex lens portion that is located on the subject side is within a range of 1.3 to 1.8 MRayl, and The concave lens portion and the convex lens portion are both made of a thermoplastic resin. the law of nature, The thermoplastic resin material of the convex lens portion has a rebound resilience of 60% or more. An acoustic lens characterized by:

[0012] 2. The acoustic lens according to claim 1, wherein the lens surface facing the subject when disposed in an ultrasonic probe is flat or convex.

[0013] 3. The acoustic lens according to claim 1 or 2, wherein the propagation speed of ultrasonic waves in the convex lens portion is at least 300 m / s slower than the propagation speed of ultrasonic waves in the concave lens portion.

[0014] 4. The thermoplastic resin that is the material of the concave lens portion is a thermoplastic hard resin, and 4. The acoustic lens according to any one of items 1 to 3, wherein the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer.

[0016] 5The difference in solubility parameter between at least one component contained in the material of the concave lens portion and at least one component contained in the material of the convex lens portion is 1 (cal / cm 3 ) 1 / 2 The first to third aspects are characterized by the following: 4 The acoustic lens according to any one of claims 1 to 5.

[0017] 6 The concave lens portion and the convex lens portion are configured by fusion bonding. 5 The acoustic lens according to any one of claims 1 to 5.

[0018] 7 The concave lens portion is configured to face the subject side, and the convex lens portion is configured to face the ultrasonic transducer side. the thermoplastic resin that is the material of the concave lens portion is a polyolefin-based thermoplastic hard resin, and The thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer containing a polyolefin-based resin component. 6 The acoustic lens according to any one of claims 1 to 5.

[0019] 8 The concave lens portion is configured to face the ultrasonic transducer side, and the convex lens portion is configured to face the subject side. The thermoplastic resin that is the material of the concave lens portion is any one of a polycarbonate-based, ABS-based, polybutylene terephthalate-based, and polyamide-based thermoplastic hard resins, and The thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer containing at least one resin component selected from the group consisting of polyester, polyamide, and polyurethane. 6 The acoustic lens according to any one of claims 1 to 5.

[0020] 9 .Items 1 to 5 8A method for manufacturing an acoustic lens according to any one of claims 1 to 5, comprising the steps of: A method for manufacturing an acoustic lens, comprising melt-bonding the concave lens portion and the convex lens portion.

[0021] 1 0 The concave lens portion and the convex lens portion are melt-bonded by insert molding. 9 Item 1. A method for manufacturing an acoustic lens according to item 1.

[0022] 1 1 The concave lens portion and the convex lens portion are melt-bonded by two-color molding. 9 Item 1. A method for manufacturing an acoustic lens according to item 1.

[0023] 1 2 An ultrasonic probe comprising an ultrasonic transducer that transmits ultrasonic waves toward a subject and receives the reflected echoes, and an acoustic lens disposed on the transmitting and receiving surface side of the ultrasonic transducer, The acoustic lens is 8 2. An ultrasonic probe comprising the acoustic lens according to claim 1.

[0024] 1 3 .1st 2 2. An ultrasonic diagnostic apparatus comprising the ultrasonic probe according to claim 1. [Effects of the Invention]

[0025] The above-described means of the present invention can provide an acoustic lens that has 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 that include the acoustic lens.

[0026] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0027] Conventional lenses are made of silicone rubber filled with microparticles, which have a high sound attenuation, in order to have a convex lens shape and an acoustic impedance close to that of the test object (within the range of 1.3 to 1.8 MRayl). However, the acoustic lens of the present invention satisfies the shape requirements by combining a concave lens section with a fast sound speed and a convex lens section with a slow sound speed, and the acoustic impedance requirements are met by the lens on the test object side, so it can be made without the need for microparticles and is effective at attenuating sound. Furthermore, the present invention is characterized in that the materials of the lens portions are all thermoplastic resins, which allows the lens portions to be easily bonded together, and makes it possible to actually provide an acoustic lens that satisfies the above-mentioned conditions, such as the sound speed, while taking bondability into consideration.

[0028] It is believed that these mechanisms of expression or action make it possible to provide an acoustic lens or the like that has small sound attenuation and acoustic impedance suitable for an ultrasonic probe. [Brief explanation of the drawings]

[0029] [Figure 1] Cross-sectional view of an acoustic lens configured so that the concave lens portion faces the subject and the convex lens portion faces the ultrasound transducer. [Figure 2] Cross-sectional view of an acoustic lens configured so that the concave lens part faces the ultrasound transducer and the convex lens part faces the subject. [Figure 3] Graph showing the relationship between rebound elasticity and sound attenuation rate in thermoplastic elastomers [Figure 4] Schematic cross-sectional view of an ultrasonic probe [Figure 5] Schematic diagram of an ultrasound diagnostic device DETAILED DESCRIPTION OF THE INVENTION

[0030] The acoustic lens of the present invention is an acoustic lens for an ultrasonic probe, and is configured by bonding a concave lens portion and a convex lens portion together, wherein 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, the acoustic impedance of the lens portion of the concave lens portion or the convex lens portion facing the subject is within the range of 1.3 to 1.8 MRayl, and the materials of the concave lens portion and the convex lens portion are both thermoplastic resin. This feature is a technical feature common to or corresponding to the following embodiments.

[0031] The acoustic lens of the present invention is preferably such that the lens surface facing the subject when disposed in an ultrasonic probe is flat or convex, since this improves adhesion to the subject, prevents air entrapment, and enables the acquisition of good tomographic images.

[0032] In the acoustic lens of the present invention, it is preferable that the propagation speed of ultrasonic waves in the convex lens portion is at least 300 m / s slower than the propagation speed of ultrasonic waves in the concave lens portion, because this reduces the curvature, thereby making it possible to reduce the lens thickness and thereby reduce sound attenuation, and because it allows for reduced wall thickness unevenness and therefore formability.

[0033] In the acoustic lens of the present invention, the thermoplastic resin that is the material of the concave lens portion is a thermoplastic hard resin, and It is preferable that the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer in terms of the propagation speed of ultrasonic waves.

[0034] In the acoustic lens of the present invention, it is preferable that the thermoplastic resin that is the material of the convex lens portion has a rebound resilience of 60% or more, since this can reduce sound attenuation due to the material properties of the convex lens portion.

[0035] In the acoustic lens of the present invention, the difference in solubility parameter between at least one component contained in the material of the concave lens portion and at least one component contained in the material of the convex lens portion is 1 (cal / cm 3 )1 / 2 In terms of bondability, it is preferable that the following conditions are met:

[0036] In the acoustic lens of the present invention, it is preferable that the concave lens portion and the convex lens portion are fused and bonded together, since there is no sound attenuation due to an adhesive layer.

[0037] The acoustic lens of the present invention is configured so that the concave lens portion faces the subject and the convex lens portion faces the ultrasonic transducer, and it is preferable that the thermoplastic resin that is the material of the concave lens portion is a polyolefin-based thermoplastic hard resin and that the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer that contains a polyolefin-based resin component, in that this satisfies the conditions of acoustic impedance and ultrasonic propagation velocity while providing good bondability.

[0038] The acoustic lens of the present invention is configured so that the concave lens portion faces the ultrasound transducer and the convex lens portion faces the subject, and it is preferable that the thermoplastic resin that is the material of the concave lens portion is any one of polycarbonate-based, ABS-based, polybutylene terephthalate-based, and polyamide-based thermoplastic hard resins, and that the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer containing at least one resin component from polyester-based, polyamide-based, and polyurethane-based resins, in that this satisfies the conditions of acoustic impedance and ultrasonic propagation velocity while providing good bondability.

[0039] The method for manufacturing an acoustic lens of the present invention is a method for manufacturing the acoustic lens according to the present invention, and is characterized in that the concave lens portion and the convex lens portion are fusion-bonded together.

[0040] In the method for manufacturing an acoustic lens of the present invention, the concave lens portion and the convex lens portion are fusion-bonded by insert molding, which is preferable because it allows fusion-bonding without using a special molding machine.

[0041] The method for manufacturing an acoustic lens of the present invention is preferable in that the concave lens portion and the convex lens portion are fusion-bonded by two-color molding, since this allows the processes from molding the first lens portion to bonding to be carried out in a single process.

[0042] The ultrasonic probe of the present invention is an ultrasonic probe including an ultrasonic transducer that transmits ultrasonic waves toward a subject and receives the reflected echoes, and an acoustic lens disposed on the transmitting / receiving surface side of the ultrasonic transducer, wherein the acoustic lens is the acoustic lens of the present invention.

[0043] The ultrasonic diagnostic apparatus of the present invention is characterized by comprising the ultrasonic probe of the present invention.

[0044] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values before and after it are included as lower and upper limits.

[0045] (1) Overview of the acoustic lens of the present invention The acoustic lens of the present invention is an acoustic lens for an ultrasonic probe, and is configured by bonding a concave lens portion and a convex lens portion together, wherein 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, the acoustic impedance of the lens portion of the concave lens portion or the convex lens portion facing the subject is within the range of 1.3 to 1.8 MRayl, and the materials of the concave lens portion and the convex lens portion are both thermoplastic resin. These features enable the adjustment of acoustic impedance and the suppression of sound attenuation while satisfying the conditions for focusing ultrasound (sound speed, lens shape).In addition, in terms of manufacturing, the material can be actually provided after taking into consideration bondability. Details are provided below.

[0046] (2) Shape of the acoustic lens The acoustic lens of the present invention is characterized in that it is configured by bonding a concave lens portion and a convex lens portion together.

[0047] The cross-sectional shape of the concave lens portion is a shape where the thickness at the center is thinner than the thickness at the periphery (so-called concave shape), and the cross-sectional shape of the convex lens portion is a shape where the thickness at the center is thicker than the thickness at the periphery (so-called convex shape).

[0048] The acoustic lens of the present invention includes both an acoustic lens 26 configured in an ultrasonic probe so that the concave lens portion 31 faces the subject (right side of the figure) and the convex lens portion 32 faces the ultrasound transducer (left side of the figure), as shown in FIG. 1, and an acoustic lens 26 configured so that the concave lens portion 31 faces the ultrasound transducer (left side of the figure) and the convex lens portion 32 faces the subject (right side of the figure), as shown in FIG. 2.

[0049] In FIGS. 1 and 2, the arrows indicate how ultrasonic waves transmitted from the ultrasonic transducer side are refracted by the acoustic lens and focused on the subject side.

[0050] The thickness and curvature of each lens portion are not particularly limited and can be designed according to the application, but from the viewpoint of sound attenuation, it is preferable that each lens portion is thin.

[0051] The acoustic lens of the present invention preferably has a lens surface that faces the subject when it is disposed in an ultrasound probe, which is flat or convex, thereby improving adhesion to the subject and preventing air entrapment, enabling the acquisition of good tomographic images.

[0052] (3)Thermoplastic resin The acoustic lens of the present invention is characterized in that the concave lens portion and the convex lens portion are both made of a thermoplastic resin, which allows the lens portions to be easily joined together by melt bonding or bonding with an adhesive.

[0053] Thermoplastic resin refers to a resin that has thermoplastic properties. In the present invention, resins that do not exhibit rubber elasticity are called hard resins, and resins that exhibit rubber elasticity are called elastomers. In other words, thermoplastic resins include thermoplastic hard resins and thermoplastic elastomers.

[0054] The material of each lens portion may contain a thermoplastic resin as the main component, and may contain small amounts of other additives as long as the thermoplasticity is not impaired.

[0055] Elastomers are composed of soft segments, which are rubber components that provide elasticity, and hard segments, which are components that flow at high temperatures but act as constraints that prevent deformation at room temperature. The soft and hard segments may be in the form of a block copolymer in which they are chemically bonded, or they may be in the form of a polymer alloy in which they are simply mixed without being chemically bonded.

[0056] When the elastomer is a polymer alloy type, a block copolymer type elastomer may be used as the soft segment.

[0057] Examples of thermoplastic hard resins include polyolefin-based, polycarbonate-based, ABS (acrylonitrile-butadiene-styrene resin)-based, polybutylene terephthalate-based, and polyamide-based thermoplastic hard resins.

[0058] Specific examples of thermoplastic hard 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-styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, methacrylic-styrene copolymer, nylon resin, butylene terephthalate resin, ethylene terephthalate resin, styrene resin, styrene-acrylonitrile copolymer, and carbonate resin.

[0059] The thermoplastic elastomer includes, for example, thermoplastic elastomers containing a resin component such as a polyolefin, polyester, polyamide, or polyurethane as a soft segment or a hard segment.

[0060] Specific examples of thermoplastic elastomers include ester-based elastomers, olefin-based elastomers, amide-based elastomers, urethane-based elastomers, styrene-based elastomers, and acrylic-based elastomers.

[0061] (4) Solubility parameter (SP value) The acoustic lens of the present invention is characterized in that the difference in solubility parameter between at least one component contained in the material of the concave lens portion and at least one component contained in the material of the convex lens portion is 1 (cal / cm 3 ) 1 / 2 In terms of bondability, it is preferable that the following conditions are met:

[0062] The solubility parameter, also known as the SP value (solubility parameter), is a value that can be used as an indicator of the solubility and compatibility of solvents and resins. If the difference in solubility parameters is small, the solubility and compatibility will be good, and the bonding between thermoplastic resins will be good.

[0063] When the material of the lens portion is a hard resin, the phrase "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, or to at least one of the hard resins when the material is composed of multiple types of hard resins.

[0064] When the lens material is an elastomer, "at least one component contained in the material" refers to at least one of the soft segments and hard segments contained in the elastomer. When there are multiple types of soft segments or hard segments, "at least one component" refers to at least one of the multiple types.

[0065] (5) Joining Since the concave lens portion and the convex lens portion according to the present invention are both made of a thermoplastic resin, the lens portions can be easily joined together by melt joining or joining with an adhesive.

[0066] (5.1) Fusion joining Joining by fusion bonding is preferable from the viewpoint of productivity, and is also preferable because it does not require an adhesive layer made of an adhesive or primer, and therefore does not affect sound attenuation due to the adhesive layer.

[0067] As a molding method for melt joining, insert molding or two-color molding is preferred.

[0068] In insert molding, one of the molded lens parts is inserted into a mold, and the resin material for the other lens part is injected into the space inside the mold to melt and bond them together. Insert molding is advantageous because it allows melt bonding without using a special molding machine.

[0069] In two-shot molding, the material for one of the lens sections is injected into a mold to fill it, and then the material for the other lens section is injected into the mold to melt and join them. Two-shot molding is advantageous because it allows the molding of the first lens section to be completed in a single process. There are two-color molding methods such as the rotary method and the core-back method, and the acoustic lens of the present invention can be molded using either method.

[0070] (5.2) Adhesive bonding The concave lens portion and the convex lens portion according to the present invention can also be bonded together using an adhesive. Bonding with an adhesive is preferable because, if each lens portion is already molded, they can be integrated without the need for a molding machine for melt bonding or the like.

[0071] The type of adhesive is not particularly limited, and any common adhesive that can bond thermoplastic resins together can be used.

[0072] In terms of bonding, it is preferable to apply a primer before bonding with an adhesive. A primer is an adhesion aid used in pretreatment before applying an adhesive. Using a primer that is suitable for the object to be bonded and the type of adhesive can improve bonding.

[0073] Considering the influence of the adhesive layer on sound attenuation and productivity, fusion bonding is preferable to bonding using an adhesive.

[0074] (6) Comparison of junctionality To compare bonding properties, the results of evaluation of the bonding properties of various thermoplastic elastomers and thermosetting elastomers (silicone rubber) to thermoplastic hard resins are shown in Table I. Details of the materials used in the bonding properties evaluation are shown in Table II.

[0075] [Table 1]

[0076] [Table 2]

[0077] The "Bonding with TPX" column in Table I shows the results when polymethylpentene (TPX) is used for the second layer of the sheet, while the "Bonding with PC" column shows the results when polycarbonate (PC) is used.

[0078] The "SP value" column in Table II lists the solubility parameters of the components that contribute to melt bonding in the case of thermoplastic resins, while in the case of silicone rubber, it simply lists the solubility parameter of the material itself.

[0079] The bondability evaluation was performed as follows. An injection molding machine (SE-50DU manufactured by Sumitomo Heavy Industries, Ltd.) was used to prepare the evaluation sheets. The melting temperature of the resin and the temperature of the mold when preparing the evaluation sheets were set to the temperatures recommended by the manufacturer of each resin material.

[0080] [Preparation of composite sheet for evaluation of fusion bonding] The first layer of sheet was produced by injecting molten resin, which would become the material for the first layer of sheet, into a mold measuring 35 mm in length, 35 mm in width, and 1 mm in thickness, and then cooling and solidifying it. The 1mm-thick first-layer sheet prepared above was set in a mold measuring 35mm long x 35mm wide x 2mm thick. The molten resin that would become the material for the second-layer sheet was injected into the space inside the mold, and then cooled and solidified to produce a composite sheet for evaluating fusion bonding.

[0081] [Preparation of composite sheet for evaluation of adhesive bonding] The molten resins were injected into a mold measuring 35 mm in length, 35 mm in width, and 1 mm in thickness, and then cooled and solidified to produce the first and second layer sheets separately. The first and second layer sheets prepared above were bonded together with an adhesive whose main component was cyanoacrylate (PPX set manufactured by Cemedine Co., Ltd.) to prepare a composite sheet for evaluating adhesive bonding.

[0082] [Preparation of composite sheet for evaluation of adhesive + primer bonding] The molten resins were injected into a mold measuring 35 mm in length, 35 mm in width, and 1 mm in thickness, and then cooled and solidified to produce the first and second layer sheets separately. A primer containing n-heptane as its main component (PPX set manufactured by Cemedine Co., Ltd.) was applied to each of the first and second layer sheets prepared above. The primer-coated first and second layer sheets were then bonded together with an adhesive containing cyanoacrylate as its main component (PPX set manufactured by Cemedine Co., Ltd.) to prepare a composite sheet for evaluating bonding using an adhesive and primer.

[0083] [Making the first layer of sheet using silicone rubber] In preparing the composite sheet for evaluation, the first layer of silicone rubber was prepared by mixing 100 parts by mass of dimethylpolysiloxane (KE742 manufactured by Shin-Etsu Chemical Co., Ltd.) with 0.5 parts by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane as a vulcanizing agent, press-molding the mixture at 165°C for 10 minutes, and then performing a secondary vulcanization at 200°C for 2 hours. The sheet was molded to a thickness of 1 mm.

[0084] [Evaluation of Bondability] The bonding properties of each of the composite sheets for evaluation prepared above were evaluated as follows and the results are shown in Table I. 〇: The bond is complete and does not come off even when pulled by hand. △: The bond is established, but it comes off when pulled by hand. ×: Not bonded.

[0085] As shown in Table I, the bonding strength between thermoplastic resins is better than that between silicone rubber and thermoplastic resins. Silicone rubber and thermoplastic resins cannot be bonded using adhesive alone, but thermoplastic resins can be bonded using adhesive alone by combining the materials appropriately. Furthermore, even if a primer is used to bond silicone rubber and thermoplastic resins with adhesive, they will peel off when pulled by hand, whereas thermoplastic resins can be bonded well together. Furthermore, silicone rubber and thermoplastic resins cannot be bonded by melt bonding, but thermoplastic resins can be bonded by combining the materials appropriately.

[0086] (7) Ultrasonic wave propagation speed 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, in order to focus the ultrasonic waves.

[0087] The greater the difference in the propagation speed of ultrasonic waves between the convex lens portion and the concave lens portion, the better, and it is preferably 300 m / s or more. The greater the difference in the propagation speed of ultrasonic waves between the convex lens portion and the concave lens portion, the higher the refraction angle of ultrasonic waves at the joint surface, and the gentler the curvature, making it easier to collect sound. Furthermore, the gentler the curvature, the thinner the lens can be. The thinner the lens thickness, the less sound attenuation can be.

[0088] The relationship between the propagation speed of ultrasound in the concave lens portion and the convex lens portion and the propagation speed of ultrasound in the subject can be adjusted as appropriate and is not particularly limited, but since the ultrasound needs to be focused, the propagation speed of ultrasound in the concave lens portion needs to be faster than the propagation speed of ultrasound in the subject. In practice, the propagation speed of ultrasonic waves in the concave lens portion is preferably faster than the propagation speed of ultrasonic waves in a living body, and is therefore preferably 1530 m / s or higher.

[0089] In view of the propagation speed of ultrasonic waves, it is preferable to use a thermoplastic hard resin as the material for the concave lens portion and a thermoplastic elastomer as the material for the convex lens portion.

[0090] (8) Acoustic impedance The acoustic lens of the present invention is characterized in that the lens portion facing the subject, out of the concave lens portion and the convex lens portion, has an acoustic impedance in the range of 1.3 to 1.8 MRayl, which makes it possible to reduce the reflection of ultrasound between the acoustic lens and the subject.

[0091] Furthermore, it is preferable that the difference in acoustic impedance between the lens portion on the subject side and the lens portion on the ultrasonic transducer side is 0.6 MRayl or less, since this can reduce the reflection of ultrasonic waves between the lens portions.

[0092] Acoustic impedance is defined as: Acoustic impedance Z [MRayl] = density ρ [kg / m 3] × speed of sound C [m / s]. The unit is generally [MRayl], where 1 [MRayl] = 1.0 × 10 6 [kg m 2 / s].

[0093] (9) Rebound elasticity In the acoustic lens of the present invention, the thermoplastic resin that is the material for the convex lens portion preferably has a rebound resilience of 60% or more. As mentioned above, in terms of the propagation speed of ultrasonic waves, it is preferable to use a thermoplastic elastomer as the material for the convex lens portion, and the higher the rebound resilience of a thermoplastic elastomer, the less sound attenuation due to the material properties tends to be (see Table III and Figure 3). Therefore, the higher the rebound resilience, the less sound attenuation due to the material properties of the convex lens portion can be, and from practical considerations, a rebound resilience of 60% or more is preferable.

[0094] (10) Acoustic characteristics evaluation Examples of materials that can be used for the lens portion are shown in Table III. However, there is no limitation on the materials that can be used for the convex lens portion.

[0095] [Table 3]

[0096] The values shown in Table III were determined by preparing measurement sheets as follows.

[0097] [Preparation of measurement sheet] The measurement sheet was produced by injecting the molten resin material into a mold measuring 35 mm in length, 35 mm in width, and 1 mm in thickness, and then cooling and solidifying it. The measurement sheets were prepared using an injection molding machine (SE-50DU manufactured by Sumitomo Heavy Industries, Ltd.) The resin melting temperature and mold temperature during measurement were set to the temperatures recommended by the manufacturer of each resin material.

[0098] 〔density〕 Measurement was carried out at 25°C in accordance with JIS C 2123.

[0099] [Speed of sound (ultrasonic wave propagation speed)] Measurements were made at 25° C. at a measurement frequency of 5 MHz using a sound velocity measuring device (Ultrasonic Industrial Co., Ltd.: Sing-around sound velocity measuring device UVM-2 type).

[0100] [Acoustic Impedance] The acoustic impedance was calculated from the density and sound velocity measured above using the following formula. Z=ρ×C Z: Acoustic impedance [MRayl] ρ: Density [kg / m 3 ] C: Speed of sound [m / s]

[0101] [Sound attenuation rate] With the test sheet placed in a water tank filled with water at 25°C, 15MHz ultrasonic waves were generated in the water using an ultrasonic pulser-receiver JPR-10C (manufactured by Japan Probe Co., Ltd.), and the amplitude of the ultrasonic waves was measured before and after they passed through the test sheet. The attenuation rate was calculated from the measured amplitude using the following formula. P x =P0e -αx P x : Amplitude after transmission P0: Amplitude before transmission e: natural logarithm α: Attenuation rate [dB / mm] x: Transmission distance [mm]

[0102] (11) Preferred material combinations A preferred combination of materials used in the acoustic lens of the present invention will now be described.

[0103] In the case of an acoustic lens configured so that the concave lens portion faces the subject and the convex lens portion faces the ultrasound transducer, as shown in Figure 1, it is preferable that the thermoplastic resin that is the material for the concave lens portion is a polyolefin-based thermoplastic hard resin, and that the thermoplastic resin that is the material for the convex lens portion is a thermoplastic elastomer that contains a polyolefin-based resin component.

[0104] The material of the lens portion on the subject side must have an acoustic impedance of 1.3 to 1.8 MRayl, but in the case of a concave lens portion, in addition to the acoustic impedance, it is preferable that the material be a thermoplastic resin and that the propagation speed of ultrasound be taken into consideration, so that the material is a polyolefin-based thermoplastic hard resin. Also, in consideration of the bondability with the material of the concave lens portion, the material of the convex lens portion on the ultrasound transducer side is preferably a thermoplastic elastomer containing a polyolefin-based resin component.

[0105] In the case of an acoustic lens configured so that the concave lens portion faces the ultrasound transducer and the convex lens portion faces the subject, as shown in Figure 2, it is preferable that the thermoplastic resin that is the material of the concave lens portion is any one of polycarbonate, ABS, polybutylene terephthalate, and polyamide thermoplastic hard resins, and that the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer containing at least one of polyester, polyamide, and polyurethane resin components.

[0106] The material of the lens portion for the subject side must have an acoustic impedance of 1.3 to 1.8 MRayl, but in the case of a convex lens portion, in addition to the acoustic impedance, it is preferable that the material be a thermoplastic resin and that the propagation speed of ultrasound be taken into consideration, so that the material is a thermoplastic elastomer containing at least one resin component selected from the group consisting of polyester, polyamide, and polyurethane. Also, in consideration of the bondability with the material of the convex lens portion, the material of the concave lens portion for the ultrasound transducer side is preferably a thermoplastic hard resin selected from the group consisting of polycarbonate, ABS, polybutylene terephthalate, and polyamide.

[0107] (12) Ultrasonic probe The ultrasonic probe of the present invention is an ultrasonic probe including an ultrasonic transducer that transmits ultrasonic waves toward a subject and receives the reflected echoes, and an acoustic lens disposed on the transmitting / receiving surface side of the ultrasonic transducer, wherein the acoustic lens is the acoustic lens of the present invention.

[0108] An ultrasonic transducer is an element (piezoelectric element) that has a piezoelectric material, can convert an electrical signal into a mechanical vibration, and vice versa, can transmit and receive ultrasonic waves, and has a pyroelectric effect.

[0109] Piezoelectric materials are materials containing piezoelectric elements that can convert electrical signals into mechanical vibrations and vice versa. Examples of piezoelectric materials that can be used include piezoelectric ceramics such as lead zirconate titanate (PZT) ceramics, lead titanate, and lead metaniobate; piezoelectric single crystals made of solid-solution single crystals such as lithium niobate, lead zinc niobate and lead titanate, and lead magnesium niobate and lead titanate; quartz; Rochelle salt; polyvinylidene fluoride (PVDF); PVDF copolymers such as polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)), which is a copolymer of VDF and trifluoroethylene (TrFE); polyvinylidene cyanide (PVDCN), which is a polymer of vinylidene cyanide (VDCN); vinylidene cyanide copolymers; odd-numbered nylons such as nylon 9 and nylon 11; aromatic nylons; alicyclic nylons; polylactic acid; polyhydroxycarboxylic acids such as polyhydroxybutyrate; cellulose derivatives; and organic polymer piezoelectric materials such as polyurea.

[0110] The thickness of the piezoelectric material is, for example, in the range of 100 to 500 μm. The ultrasonic transducer is used with an I / O (Input / Output) electrode and a GND (Ground) electrode attached to both sides.

[0111] The configuration other than the acoustic lens and the ultrasonic transducer is not particularly limited, but may be, for example, a configuration as shown in FIG.

[0112] The ultrasonic probe 2 shown in FIG. 4 includes a back layer 21, an I / O (Input / Output) electrode 22 as a first electrode, an ultrasonic transducer (piezoelectric element) 23, a GND (Ground) electrode 24 as a second electrode, an acoustic matching layer 25, and an acoustic lens 26.

[0113] (13) Ultrasound diagnostic equipment The ultrasonic diagnostic apparatus of the present invention is characterized by comprising the ultrasonic probe of the present invention.

[0114] The configuration other than the ultrasonic probe is not particularly limited, but for example, the configuration shown in FIG. 5 can be used.

[0115] The ultrasound diagnostic device 100 shown in Fig. 5 includes an ultrasound diagnostic device main body 1 and an ultrasound probe 2. The ultrasound diagnostic device main body 1 is connected to the ultrasound probe 2 via a cable 3. An electrical drive signal is sent to the ultrasound probe 2, causing the ultrasound probe 2 to transmit ultrasound waves to the subject, and an internal state of the subject is visualized as ultrasound image data based on a received signal, which is an electrical signal generated by the ultrasound probe 2 in response to ultrasound waves reflected from within the subject and received by the ultrasound probe 2. The ultrasound diagnostic device main body 1 also includes an operation input unit 11 and a display unit 17. [Industrial Applicability]

[0116] The present invention can be used in an acoustic lens that has low sound attenuation and acoustic impedance suitable for an ultrasonic probe, a manufacturing method thereof, and an ultrasonic probe and ultrasonic diagnostic device that include the acoustic lens. [Explanation of symbols]

[0117] 1. Ultrasound diagnostic device 2 Ultrasound probes 3 Cable 11 Operation input section 17 Display 21 Back layer 22 I / O electrode 23 Ultrasonic transducer 24 GND electrode 25 Acoustic matching layer 26 Acoustic Lens 31 Concave lens part 32 Convex lens part 100 Ultrasound diagnostic equipment

Claims

1. 1. An acoustic lens for an ultrasound probe, comprising: The concave lens portion and the convex lens portion are bonded together. 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, The acoustic impedance of the lens portion of the concave lens portion and the convex lens portion that is located on the subject side is within a range of 1.3 to 1.8 MRayl, and the concave lens portion and the convex lens portion are both made of a thermoplastic resin; An acoustic lens characterized in that the thermoplastic resin that is the material of the convex lens portion has a rebound elasticity of 60% or more.

2. 2. The acoustic lens according to claim 1, wherein the lens surface facing the subject when disposed in the ultrasonic probe is flat or convex.

3. 3. The acoustic lens according to claim 1, wherein the propagation speed of ultrasonic waves in the convex lens portion is at least 300 m / s slower than the propagation speed of ultrasonic waves in the concave lens portion.

4. the thermoplastic resin that is the material of the concave lens portion is a thermoplastic hard resin, and 4. The acoustic lens according to claim 1, wherein the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer.

5. The difference in solubility parameter between at least one component contained in the material of the concave lens portion and at least one component contained in the material of the convex lens portion is 1 (cal / cm ３ ) １／２ 5. The acoustic lens according to claim 1, wherein:

6. 6. The acoustic lens according to claim 1, wherein the concave lens portion and the convex lens portion are fused and bonded together.

7. The concave lens portion is configured to face the subject side, and the convex lens portion is configured to face the ultrasound transducer side, the thermoplastic resin that is the material of the concave lens portion is a polyolefin-based thermoplastic hard resin, and 7. The acoustic lens according to claim 1, wherein the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer that contains a polyolefin-based resin component.

8. The concave lens portion is configured to face the ultrasonic transducer side, and the convex lens portion is configured to face the subject side. the thermoplastic resin that is the material of the concave lens portion is any one of a polycarbonate-based, ABS-based, polybutylene terephthalate-based, and polyamide-based thermoplastic hard resins, and 7. The acoustic lens according to claim 1, wherein the thermoplastic resin that is the material of the convex lens portion is a thermoplastic elastomer containing at least one resin component selected from the group consisting of polyester, polyamide, and polyurethane.

9. A method for manufacturing an acoustic lens according to any one of claims 1 to 8, comprising the steps of: A method for manufacturing an acoustic lens, comprising melt-bonding the concave lens portion and the convex lens portion.

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

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

12. An ultrasonic probe including an ultrasonic transducer that transmits ultrasonic waves toward a subject and receives the reflected echoes, and an acoustic lens disposed on the transmitting and receiving surface side of the ultrasonic transducer, An ultrasonic probe, wherein the acoustic lens is the acoustic lens according to any one of claims 1 to 8.

13. An ultrasonic diagnostic apparatus comprising the ultrasonic probe according to claim 12.

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