JP3934448B2 - Ultrasonic probe and manufacturing method thereof - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an ultrasound probe used in an ultrasound diagnostic apparatus that renders an ultrasound diagnostic image by electrically or mechanically scanning ultrasound, and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, this type of ultrasonic probe has been published in `` Revised Medical Ultrasound Equipment Handbook (Figure 2.39 on page 42) edited by Memoto Electronics Machinery Association, April 1985: Corona Corp. '' The described arrangement is known. Hereinafter, a conventional ultrasonic probe will be described.
[0003]
FIG. 7 is an explanatory diagram showing an outline of the structure of a piezoelectric plate and an acoustic matching layer of a conventional ultrasonic probe and a manufacturing method thereof. The piezoelectric plate 21 shown in FIGS. 7A and 7B converts an electrical signal transmitted from the ultrasonic diagnostic apparatus main body (not shown) into mechanical vibration. In order to efficiently transmit an ultrasonic signal transmitted from the piezoelectric plate 21 to a living body that is an object to be measured, a first acoustic matching layer 22 and a second acoustic matching layer 23 are provided as acoustic matching layers on the front surface of the piezoelectric plate 21. Are bonded by an adhesive layer 24. FIG. 7A is an exploded view of a stage before the first acoustic matching layer 22, the second acoustic matching layer 23, and the piezoelectric plate 21 are joined. FIG. 7B shows a state in which these components are joined by the adhesive layer 24. Show.
[0004]
The structure in which the piezoelectric plate 21 and the acoustic matching layers 22 and 23 are integrated is generally called an acoustic element, and the acoustic element of a conventional ultrasonic probe receives an electrical signal transmitted from the ultrasonic diagnostic apparatus body. The piezoelectric plate 21 is converted into mechanical vibration, and the mechanical vibration of the piezoelectric plate 21 is sent to the human body via the acoustic matching layer, and the reflected ultrasonic signal from the boundary of each organization in the human body is The piezoelectric plate 21 converts the signal again into an electric signal through a path opposite to that at the time of transmission, and a tomographic image of the human body is drawn on the display screen of the ultrasonic diagnostic apparatus.
[0005]
On the other hand, regarding an ultrasonic probe using a photocurable resin, one described in Japanese Patent Publication No. 7 (1995) -12239 has been proposed, but the present invention provides an array type ultrasonic probe. This is a method of applying a photocurable resin to the divided groove portions, and is not an acoustic matching layer itself or a manufacturing method for forming the acoustic matching layer itself.
[0006]
Furthermore, as another prior art, it has been proposed to use a photo-curing resin as an acoustic matching layer, and to mix the UV-transparent glass powder into this and cure the resin by UV (Japanese Patent Laid-Open No. 5 (1993)- No. 15530).
[0007]
However, in the conventional ultrasonic probe, in order to efficiently transmit the vibration of the piezoelectric plate to the living body, a material having an acoustic impedance that is an intermediate value between the acoustic impedances of the piezoelectric plate and the living body is used. It was difficult to form the acoustic matching layer with a desired thickness.
[0008]
That is, in the conventional structure, in order to manufacture an ultrasonic probe with small variation in acoustic characteristics and high acoustic performance, it is necessary to first realize an acoustic matching layer with a desired thickness. High-precision processing operations and thickness control were necessary for polishing and the like. In addition, since one or more acoustic matching layers prepared in advance are generally bonded with an adhesive, the acoustic matching layer is highly accurate because it is bonded to the entire surface of the piezoelectric plate with an adhesive. Even if it is processed, there has been a problem that due to variations in the bubbles in the adhesive layer and the thickness of the adhesive layer, the characteristics of the ultrasonic probe as a whole may be varied or deteriorated.
[0009]
[Problems to be solved by the invention]
The present invention solves the above-described conventional problems, and creates an acoustic matching layer with a required thickness with high accuracy and forms it without bonding, thereby allowing variations in the thickness of the adhesive layer and bubbles in the adhesive layer. An object of the present invention is to provide an ultrasonic probe that is less likely to cause problems due to contamination and a manufacturing method thereof.
[0010]
Furthermore, an ultrasonic probe having an acoustic matching layer that can easily change the acoustic impedance from the acoustic impedance of the piezoelectric plate to the acoustic impedance of the living body so that the vibration of the piezoelectric plate can be transmitted to the living body more efficiently. And its manufacturing method.
[0011]
[Means for Solving the Problems]
In order to solve the above problem, an ultrasonic probe according to the present invention transmits a piezoelectric element that transmits and receives ultrasonic waves and ultrasonic waves that are transmitted and received by the piezoelectric elements to an object to be measured. Two or more types In an ultrasonic probe having an acoustic matching layer,
The acoustic matching layer is Liquid It is formed with a hardened layer that is photocured by laser light irradiation Using the sedimentation rate of the filler mixed in the resin for optical modeling, the lower layer of the filler abundance, density, or particle size is increased, the surface layer is decreased, and the acoustic impedance in the thickness direction is reduced. The hardened layer having a predetermined thickness is laminated on the piezoelectric element one by one. It is characterized by being.
[0012]
Next, the ultrasonic probe manufacturing method of the present invention includes an acoustic matching layer that transmits ultrasonic waves from a piezoelectric element that transmits and receives ultrasonic waves to an object to be measured. Above In the method of manufacturing an ultrasonic probe, the acoustic matching layer is formed in a cured layer obtained by irradiating a liquid optical modeling resin supplied into a tank with a laser beam and photocuring into a predetermined shape. To do.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, the acoustic matching layer is formed of a cured layer obtained by photocuring a resin for optical modeling by laser light irradiation, so that an acoustic matching layer having a desired thickness, high thickness accuracy, and less variation in characteristics can be obtained. Can be easily created.
[0014]
In the ultrasonic probe of the present invention, it is preferable that the acoustic matching layer is formed by laminating a cured layer of a photocurable resin on the piezoelectric element. As a result, the acoustic matching layer can be formed on the piezoelectric plate without adhering to it, so there is no risk of bubbles due to the use of an adhesive, and an acoustic matching layer with little variation in characteristics is easily created. be able to.
[0015]
In the ultrasonic probe of the present invention, it is preferable that an acoustic matching layer is formed by mixing an arbitrary filler in a photocurable resin. Thereby, an acoustic matching layer having an appropriate acoustic impedance required for efficiently transmitting and receiving ultrasonic waves can be easily created.
[0016]
In the ultrasonic probe of the present invention, it is preferable that the acoustic matching layers have sequentially different acoustic impedances in the thickness direction. Thereby, the ultrasonic signal of a piezoelectric plate can be transmitted and received more efficiently.
[0017]
In the ultrasonic probe of the present invention, it is preferable that the acoustic matching layer is formed by laminating a plurality of layers having different filler contents, so that acoustic matching layers having different acoustic impedances are sequentially formed. Thereby, the ultrasonic signal transmitted / received from a piezoelectric plate corresponding to the individual difference or site | part of a to-be-measured object can be transmitted efficiently.
[0018]
In the ultrasonic probe of the present invention, it is preferable that the acoustic matching layer is formed of a mixture of fillers having two or more particle sizes or a photocurable resin in which fillers different in the layer direction are mixed. Thereby, an acoustic matching layer having an appropriate acoustic impedance required for efficiently transmitting and receiving ultrasonic waves can be easily created, and ultrasonic signals of the piezoelectric plate can be transmitted and received efficiently.
[0019]
In the ultrasonic probe of the present invention, the acoustic matching layer is preferably formed of a mixture of two or more kinds of fillers or a photocurable resin in which fillers different in the layer direction are mixed. Thereby, the ultrasonic signal of a piezoelectric plate can be transmitted / received efficiently.
[0020]
In the ultrasonic probe of the present invention, it is preferable that one or more of tungsten, ferrite, and alumina are mixed as a filler in the photocurable resin. Thereby, an acoustic matching layer having an intermediate value between the acoustic impedance of the piezoelectric element and the acoustic impedance of the human body can be easily formed, and an ultrasonic signal can be transmitted and received efficiently. In the above, ferrite refers to a crystal structure of iron (Fe).
[0021]
Next, according to the method of the present invention, the acoustic matching layer is formed of a cured layer obtained by irradiating the liquid optical modeling resin supplied into the tank with a laser beam and photocuring the resin into a predetermined shape. Thus, an acoustic matching layer having a high thickness accuracy and a small variation in characteristics can be easily produced.
[0022]
Moreover, it is preferable to mix 0 mass% or more and 2000 mass% or less of fillers with the said resin.
[0023]
In addition, it is preferable to use the sedimentation rate of the filler mixed with the resin so that the lower layer filler abundance is high, the surface layer filler abundance is low, and the acoustic impedance in the thickness direction is different.
[0024]
The acoustic matching layer may be formed of a plurality of resin layers, the lower resin layer having a higher density, and the surface resin layer having a lower density, so that the acoustic impedance in the thickness direction is different. preferable.
[0025]
The density of the resin layer is preferably controlled by varying at least one selected from the amount of filler added, the average particle size, and the density.
[0026]
Hereinafter, specific embodiments of the present invention will be described with reference to FIGS.
[0027]
(Embodiment 1)
As shown in FIG. 1A, the ultrasonic probe 20 according to the first embodiment of the present invention includes a piezoelectric plate 1 that is a piezoelectric element that transmits and receives ultrasonic waves, and acoustic matching for efficiently transmitting and receiving the ultrasonic waves. Layer (gradually matching layer) 4, backing material 10 that holds piezoelectric plate 1 and suppresses the loss of efficiency due to leakage of ultrasonic waves to the rear, and ultrasonic waves to be measured on any object to be measured (not shown) The lens includes an acoustic lens 11 for efficiently focusing on a position, an electrode wiring material 12, a cable (not shown), a connector (not shown), and the like. Among these, the acoustic matching layer 4 uses a liquid curable resin for optical modeling (hereinafter referred to as a liquid photocurable resin) as described later, and applies a method generally called an optical modeling method to apply liquid light. It was formed by curing a part of the curable resin.
[0028]
A method of curing a part of the liquid photocurable resin 2 in FIG. 1B will be described. The liquid photocurable resin 2 is filled in the tank 6, and the upper surface (work support surface) 7a of the vertical moving table 7 corresponds to a predetermined thickness to be cured from the liquid surface of the liquid photocurable resin 2 at the beginning. It is located below that distance. By irradiating laser light (hereinafter referred to as laser) 3 such as an ultraviolet laser or an Ar laser emitted from the laser emitter 8 at this position, the part irradiated with the laser 3 of the liquid photocurable resin can be cured. .
[0029]
As an irradiation method, while controlling by an irradiation position control means (not shown) such as a digital scan mirror or a moving means (not shown) of the laser emitter 8, a wide range in a state of masking spots or other than necessary portions. Irradiation is directed toward the liquid photocurable resin 2 on the support surface of the vertical movement table 7. By performing the irradiation for a predetermined time, a hardened layer of a thin film having a predetermined shape can be formed on the support surface of the vertical movement table 7.
[0030]
Next, the hardened layer of the thin film is sequentially lowered at a predetermined speed by using the vertical movement table 7, and the laser 3 is irradiated at a predetermined timing. By forming and laminating one layer at a time in this manner, a cured layer having a desired thickness is finally formed.
[0031]
Here, the liquid photocurable resin 2 is composed of a photopolymerizable oligomer, a reactive diluent, a photopolymerization initiator, and the like, and has a property that only a portion irradiated with light is cured by exposure. If necessary, photopolymerization assistants, additives and the like are blended. Depending on the type of photopolymerizable oligomer, there are two types: a type that cures by radical polymerization reaction such as urethane acrylate, epoxy acrylate, ester acrylate, and acrylate, and a type that cures by cationic polymerization reaction such as epoxy and vinyl ether. Separated. Which type of resin is used depends on the reaction rate, shrinkage strain, dimensional accuracy, heat resistance, strength, and the like.
[0032]
In general, as the photocurable resin, those containing urethane acrylate and epoxy photopolymerizable oligomers are mainly used, but urethane acrylate has a high reaction rate and a large intermolecular cohesion, Mechanical strength / thermal strength is more advantageous than epoxy systems, and is suitable when importance is placed on strength. On the other hand, epoxy systems are characterized by a slow polymerization reaction rate and small shrinkage strain. Therefore, the epoxy-based optical modeling resin is advantageous in terms of dimensional accuracy, and is suitable when importance is placed on accuracy.
[0033]
Specific examples of epoxy stereolithography resins are "HS-681" (product name) manufactured by Asahi Denka Kogyo Co., Ltd., and "SOMOS8100" (product name) manufactured by DSM-SOMOS (the same from JSR is the SCR-8100 series) "SL-7540" (trade name) manufactured by Vantico (formerly Ciba Specialty Chemicals). A specific example of the urethane acrylate stereolithography resin is Teijin Seisakusho "TSR-1938M" (trade name).
[0034]
A method of laminating and forming a cured layer of a photocurable resin directly on the base plate 13 in general, using the curing means of the liquid photocurable resin 2 using the optical modeling method configured as described above Will be described with reference to FIG.
[0035]
First, the base plate 13 fixed on the up-and-down moving base 7 is immersed in the liquid photocurable resin 2 filled in the tank 6, and the base plate 13 is formed by the laser 3 emitted from the laser emitter 8. The liquid photocurable resin 2 existing on the top is exposed to cure the liquid photocurable resin 2 on the base plate 13.
[0036]
While moving the laser emitter 8 parallel to the base plate 13 (in the horizontal direction) based on the XY coordinate or polar coordinate position data, uniformly irradiate the liquid rice curable resin 2 with the laser 3 at a predetermined position. Thus, the liquid photocurable resin 2 is cured on the base plate 13 to form the thin acoustic matching layer 4.
[0037]
Further, although not shown in the drawing, the vertical movement table 7 is lowered by a predetermined distance (not shown), and the laser 3 is irradiated again, so that the acoustic matching layer 4 made of a photo-curing resin that has already been cured is applied. A new hardened layer of the liquid photocurable resin 2 can be formed on the thin layer. By controlling the distance by which the vertical moving table 7 is lowered in this way, by repeating the above operation so that the total moving distance of the vertical moving table 7 becomes the dimension of the acoustic matching layer 4 that is finally required. The acoustic matching layer 4 having a desired thickness can be formed on the base plate 13.
[0038]
As described above, according to the first embodiment of the present invention, it is not necessary to use a material that is individually polished to a desired thickness, and acoustic matching is performed on the base plate 13 without using an adhesive. The layer 4 can be formed.
[0039]
Therefore, in the ultrasonic probe according to the first embodiment of the present invention, since the adhesive layer 24 does not exist between the piezoelectric plate 1 as the base plate and the acoustic matching layer 4, the conventional general adhesion Each acoustic element after being divided by dicing with a desired thickness and high thickness accuracy, without any variation of the adhesive layer thickness of about 2μm to 15μm that can occur in the laminating method, and the influence of bubbles mixed in the adhesive layer 24 Therefore, a stable acoustic matching layer can be easily produced, and a highly reliable ultrasonic probe can be provided.
[0040]
(Embodiment 2)
Next, a method of forming the acoustic matching layer 4 having different acoustic impedances will be described with reference to FIG.
[0041]
As shown in FIG. 3, when the cured layer of the liquid photocurable resin 2 is formed by lamination, the liquid photocurable resin 2 in the tank 6 has a fine powder, fiber, or plate shape as a filler. By mixing the shaped filler 9, the acoustic matching layer 4 having desired acoustic impedance characteristics can be formed.
[0042]
The filler 9 to be mixed here is mixed when the liquid photocurable resin 2 is in a liquid state, and the filler 9 is uniformly dispersed using a stirrer or the like. As the filler 9 to be mixed, tungsten, lalite, alumina, or the like, and an average particle diameter of about 1 μm to 10 μm is appropriate.
[0043]
As the acoustic impedance of the acoustic matching layer 4, it is common to use a material having an intermediate value between the acoustic impedance of the piezoelectric plate 1 (about 30 Mray) and the acoustic impedance of the human body (about 1.5 Mray). For example, when the material and particle size of the filler 9 are the same so that the range of about 30 Mrayl to about 1.5 Mrayl is achieved, the amount of the filler 9 mixed in the liquid photocurable resin 2 is adjusted to approach the target acoustic impedance. It becomes possible.
[0044]
By doing so, it is possible to easily create an acoustic matching layer having a desired thickness and a high thickness accuracy with little variation, and it is possible to provide a highly reliable ultrasonic probe.
[0045]
Here, a set of a plurality of layers having gradually different acoustic impedances is hereinafter referred to as a marginal matching layer.
[0046]
(Embodiment 3)
Next, a method for manufacturing the acoustic matching layer 4 according to the ultrasonic probe of the third embodiment of the present invention will be described with reference to FIGS. 4A to 4C.
[0047]
As shown in FIGS. 4A to 4C, in addition to the second embodiment, when the cured layer of the liquid photocurable resin 2 is formed in a laminate, the amount of the filler 9 (mixing amount) using a plurality of tanks 6 is used. ) Are gradually changed for each layer to be sequentially laminated.
[0048]
The material of the filler 9 is larger than the density of the liquid photocurable resin 2, and the liquid photocurable resin 2 including the filler 9 is gradually increased by gradually increasing the amount of the filler 9 mixed in the liquid photocurable resin 2. The average density will increase. On the other hand, the acoustic impedance is expressed by the product of the density of the material and the speed of sound transmission (sound speed), and as can be seen from this, as the average density of the entire liquid photocurable resin 2 increases, Impedance will also increase.
[0049]
From this, the acoustic matching layer 4 in which the acoustic impedance is sequentially changed in the thickness direction of the acoustic matching layer 4 can be formed by laminating the liquid photocurable resin 2 by sequentially changing the mixing amount of the filler 9. . In this way, by adjusting the amount of filler 9 to be mixed, the change in acoustic impedance can be set in a form of arbitrary change such as a step change or a linear or series change according to the distance in the thickness direction. it can.
[0050]
As specific means for changing the amount of the filler 9, the liquid photocurable resin 2 is in a liquid state, the filler 9 is uniformly dispersed, and various types are mixed and dispersed so as to obtain a desired acoustic impedance. The tank 6 is prepared, and from the tank 6 with a large amount of filler mixed to the tank 6 with a small amount of filler, the acoustic matching layer 4 is stacked one by one for each tank and moved to another tank 6 with a different amount of filler 9. (Acoustic tank) soaking and laminating on the surface of the previously cured layer, the acoustic matching layer 4 in which the thickness direction acoustic impedance is gradually changed can be laminated.
[0051]
Again, the filler 9 to be mixed is preferably tungsten, ferrite, alumina, etc., and the average particle size is preferably about 1 μm to 10 μm. Hereinafter, the entire acoustic matching layer 4 composed of a plurality of layers in which the acoustic impedance is gradually changed in the thickness direction is referred to as a gradually changing matching layer 5.
[0052]
The acoustic impedance of the grading matching layer 5 can be gradually changed from the acoustic impedance of the piezoelectric plate 1 to the acoustic impedance of the human body that is the object to be measured, so it varies from about 30 Mrayl to a value of about 1.5 Mrayl. The amount of filler 9 is gradually changed so that the acoustic impedance is adjusted. That is, it is preferable that the lower layer is formed so that the density of the lower layer is increased and the density of the upper layer is gradually decreased.
[0053]
At this time, the amount of the filler 9 to be mixed can be arbitrarily set in accordance with the distance in the thickness direction, such as a stepwise, linear, or series change in the acoustic impedance change. An ultrasonic signal transmitted / received from the piezoelectric plate 1 corresponding to individual differences or parts can be efficiently transmitted.
[0054]
(Embodiment 4)
Next, a method for manufacturing the acoustic matching layer 4 of the ultrasonic operator according to the fourth embodiment of the present invention will be described with reference to FIGS.
[0055]
As shown in FIGS. 5A to 5C, in addition to the first embodiment, when the acoustic matching layer 4 is formed by laminating the liquid photocurable resin 2, the density of the filler 9 itself may be changed. The average density of the entire liquid photocurable resin 2 can be changed, and the acoustic matching layer 4 in which the acoustic impedance is sequentially changed in the thickness direction is formed.
[0056]
As the filler 9, in order of density, tungsten (19.3 g / cm ^Three ), Ferrite (7.015 g / cm ^Three ), Alumina (3.95 g / cm ^Three ) Or the like is used, but other materials may be used.
[0057]
As a specific method of changing the average density of the liquid photocurable resin 2 as a whole using these fillers 9, as described in the second embodiment, several types of tanks 6 are prepared, and each tank is prepared. In FIG. 6, the filler 9 having a different density is mixed and stirred in the liquid photocurable resin 2 in a liquid state, and the acoustic matching layer 4 is sequentially laminated and cured in each tank 6 to form the gradually changing matching layer 5. it can.
[0058]
When tungsten, ferrite, or alumina is used as the filler 9, the liquid photocuring property is obtained by mixing and stirring tungsten in the first tank 6, ferrite in the second tank 6, and alumina in the third tank 6. The resin 2 was prepared, and the acoustic impedance of the acoustic matching layer 4 was gradually changed from a large value to a small value by sequentially laminating from the first tank 6 in which the density of the filler 9 was large. As described above, the acoustic impedance of the gradually changing matching layer 5 is gradually changed from the acoustic impedance of the piezoelectric plate 1 to the acoustic impedance of the human body. For this reason, the acoustic impedance is adjusted by mixing materials with different densities of the fillers 9 sequentially in the thickness direction of lamination so as to change from about 30 Mrayl to about 1.5 Mrayl.
[0059]
In addition, when materials having the same particle size and different densities are mixed in the liquid photocurable resin 2 in the liquid state at the same time, the settlement speed of the filler 9 having a high density is faster than the settlement speed of the filler 9 having a low density. When left standing for a certain period of time, in the liquid photocurable resin 2, depending on the depth, there is a filler 9 with a higher density in the deeper side, and a filler 9 with a lower density in the shallower side. Thus, it is possible to create a state in which the density of the filler 9 is different in the depth direction. By curing the liquid photocurable resin 2 in this state, the gradual change matching layer 5 can be formed even if only one tank 6 is used.
[0060]
(Embodiment 5)
Next, the manufacturing method of the acoustic matching layer 4 of the 5th Embodiment of this invention is demonstrated using FIG. 6A-C.
[0061]
As shown in FIGS. 6A to 6C, in addition to the first embodiment, when the liquid photocurable resin 2 is formed by lamination, even if the particle size of the filler 9 is changed, the thickness is similar to the above. The acoustic matching layer 4 is formed by gradually changing the acoustic impedance in the direction. Even if the material of the filler 9 is the same, changing the particle size changes the overall specific gravity (or weight) when mixed in the liquid photocurable resin, so that the acoustic impedance can be changed.
[0062]
Therefore, it is possible to easily create an acoustic matching layer having an appropriate acoustic impedance (slowly changing from the acoustic impedance of the piezoelectric plate 1 to the acoustic impedance of the human body) required for efficiently transmitting and receiving ultrasonic waves. The ultrasonic signal of the piezoelectric plate can be transmitted and received efficiently.
[0063]
As a specific method for changing the particle size of the filler 9, several types of tanks 6 containing the liquid photocurable resin 2 mixed and stirred with fillers 9 having different particle diameters are prepared in advance and stacked one by one in each tank 6. By doing so, the gradually changing matching layer 5 can be formed by a laminating method. As the material of the filler 9, any of the above materials may be used, or other materials may be used. The average particle size is generally about 1 to 10 μm, but a material having a larger diameter may be used as necessary.
[0064]
Note that the weight ratio of the filler 9 is mixed, for example, when the first layer is cured, 5% is mixed and stirred and cured, and before the second layer is cured, the weight ratio is further 5%. By repeating the procedure of adding the filler 9 and stirring and curing, the acoustic matching layer 4 in which the acoustic impedance is gradually changed can be formed even if one tank 6 is used.
[0065]
Moreover, it is also possible to combine the second to fifth embodiments, and in this case, the acoustic impedance can be changed more finely.
[0066]
In addition to the method of laminating a photo-curing resin directly on the piezoelectric plate 1, the acoustic matching layer is formed by forming the acoustic matching layer 4 alone and then adhering it onto the piezoelectric plate 1 to form ultrasonic waves. A probe may be formed.
[0067]
According to the above embodiment, the acoustic matching layer 4 on the piezoelectric plate 1 can be gradually changed from the acoustic impedance equivalent to the acoustic impedance of the piezoelectric plate 1 to the equivalent of the acoustic impedance of the living body. The acoustic matching layer 4 in which the acoustic impedance gradually changes in the thickness direction, which cannot be realized by the method of bonding the individual acoustic matching layers 4, can be created, and an ideal acoustic matching layer can be realized.
[0068]
The present invention will be described more specifically below.
[0069]
Example 1
“TSR-820” (trade name) manufactured by Teijin Seiki Co., Ltd. was used as an optical modeling resin. In the first tank, 1385 mass% of tungsten powder having an average particle size of 13 μm was blended with “TSR-820” resin. In the second tank, 400 mass% of tungsten powder having a particle diameter of 3 to 5 μm was blended with “TSR-820” resin. In the third tank, only “TSR-820” resin was used 100%.
[0070]
The laser beam is a semiconductor solid laser (wavelength 355 nm), the laser irradiation power is 500 mW, the laser beam scanning speed is 2 m / sec, and the irradiation area is 250 mm. ² It was. The thickness in one scan was 100 μm.
[0071]
A first layer is formed using the resin solution in the first tank under the above conditions, then a second layer is formed using the resin solution in the second tank, and then the resin solution in the third tank is used. Three layers were formed, and the thickness of each layer was 100 μm, and a laminated gradually changing matching layer having a total thickness of 300 μm was formed.
[0072]
The characteristics of the obtained laminated gradually varying matching layer were as follows. That is, the acoustic impedance Z of the first layer Z = 17 Mrayl, the acoustic impedance Z of the second layer Z = 7.7 Mrayl, and the acoustic impedance Z of the third layer Z = 2.8 Mrayl. It was confirmed that the acoustic impedance value gradually changed from the acoustic impedance of the piezoelectric plate (about 30 Mrayl) to 1.5 Mrayl which is the acoustic impedance of the human body to form a matched layer.
[0073]
In this way, when one matching layer is bonded by the conventional method, the characteristics of the piezoelectric element, for example, the ratio band at the position of −6 dB (with respect to the center frequency f of the ultrasonic signal transmitted by the piezoelectric plate) The ratio of the frequency bandwidth fw at the −6 dB position from the gain at the center frequency = fw / f) is 50%, whereas the ratio band of the piezoelectric element in which three matching layers are formed by the method of the present invention Was able to realize a piezoelectric element with a broad bandwidth of almost 100% (in the case of two layers, the relative bandwidth is 60%).
[0074]
Further, the piezoelectric element including the acoustic matching layer is divided into a plurality of small pieces in a slice shape with a groove in the thickness direction as a next step, and electrodes are individually connected to each small piece. At this time, the variation in the characteristics of each small piece (dividing element) after the division is largely related to the characteristics of the entire ultrasonic probe, but in the ultrasonic probe obtained by the method of the present invention, unlike the conventional case, Since it is not necessary to bond with an adhesive, each small piece (divided element) can be formed as a highly accurate acoustic matching layer without variations in the thickness accuracy of the adhesive layer or bubbles due to bubbles as a whole.
[0075]
In this way, frequency characteristics such as band characteristic variation and center frequency deviation, sensitivity fluctuations, and the like could be suppressed to less than half of the conventional ones.
[0076]
As described above, the ultrasonic probe of the present invention can easily produce an acoustic matching layer having a desired thickness, a high thickness accuracy, and a small variation in characteristics. A probe can be provided.
[0077]
【The invention's effect】
According to the method of the present invention, since the acoustic matching layer can be formed on the piezoelectric plate without bonding, there is no risk of generation of bubbles due to the use of an adhesive, and an acoustic matching layer with little variation in characteristics is obtained. Can be easily created.
[Brief description of the drawings]
FIG. 1A is a schematic explanatory diagram of an ultrasonic probe according to a first embodiment of the present invention, and B is a diagram for explaining a method of forming an acoustic matching layer of the ultrasonic probe by an optical modeling method. It is a schematic explanatory drawing.
FIG. 2 is an explanatory diagram of a method for forming an acoustic matching layer directly on the piezoelectric plate according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of a method for forming a change-matching matching layer of an ultrasonic probe in a second embodiment of the present invention.
FIGS. 4A to 4C are explanatory views of a method for forming a gradually changing matching layer by transferring an ultrasonic probe according to a third embodiment of the present invention. FIGS.
FIGS. 5A to 5C are explanatory diagrams of a method for forming a gradually varying matching layer by an ultrasonic probe transfer tank according to a fourth embodiment of the present invention. FIGS.
FIGS. 6A to 6C are explanatory diagrams of a method for forming a gradually changing matching layer by transferring an ultrasonic probe according to a fifth embodiment of the present invention. FIGS.
FIG. 7A is an exploded view for explaining a state before bonding of a conventional acoustic matching layer, and FIG. 7B is an explanatory view for showing a bonding state of a conventional acoustic matching layer.
[Explanation of symbols]
1 Piezoelectric plate
2 Liquid photo-curing resin
3 Laser 4 acoustic matching layer
5 Gradation matching layer
6 tanks
7 Vertical movement table
7a Top surface of vertical movement table (work support surface)
8 Laser emitter
9 Filler
10 Backing material
11 Acoustic lens
12 Electrode wiring material
13 Base plate

Claims (11)

In an ultrasonic probe having a piezoelectric element that transmits and receives ultrasonic waves, and two or more acoustic matching layers that transmit ultrasonic waves transmitted and received by the piezoelectric elements to an object to be measured,
The acoustic matching layer is formed of a cured layer obtained by photocuring a liquid optical modeling resin by laser light irradiation, and using the settling rate of the filler mixed with the optical modeling resin, the filler abundance and density Or the particle size is formed such that the lower layer is higher and the surface layer is lower so that the acoustic impedance in the thickness direction is different, and the cured layer having a predetermined thickness is laminated on the piezoelectric element one by one. An ultrasonic probe characterized by   The ultrasonic probe according to claim 1, wherein the acoustic matching layer is laminated on the piezoelectric element. The ultrasonic probe according to claim 1 , wherein the filler is a filler having an average particle diameter of two or more types. The ultrasonic probe according to claim 1 , wherein the filler is a filler having two or more densities. The ultrasonic probe according to claim 1 , wherein the filler is at least one filler selected from tungsten, ferrite, and alumina.   The ultrasonic probe according to claim 1, wherein the acoustic matching layer is formed of a plurality of layers, and there is no adhesive layer between the layers.   The ultrasonic probe according to claim 1, wherein the acoustic matching layer is formed of a plurality of layers, and no bubbles exist between the layers. In the method of manufacturing an ultrasonic probe according to any one of claims 1 to 7 , further comprising an acoustic matching layer that transmits the ultrasonic waves from a piezoelectric element that transmits and receives ultrasonic waves to an object to be measured.
The acoustic matching layer is formed on a hardened layer obtained by irradiating a liquid optical modeling resin supplied into a tank with a laser beam and photocuring the resin into a predetermined shape. The method for manufacturing an ultrasonic probe according to claim 8 , wherein the filler is at least one filler selected from tungsten, ferrite, and alumina. 9. The method of manufacturing an ultrasonic probe according to claim 8, wherein the acoustic matching layer is formed of a plurality of layers, and no adhesive layer is present between the layers. The method of manufacturing an ultrasonic probe according to claim 8 , wherein the acoustic matching layer is formed of a plurality of layers, and bubbles do not exist between the layers.

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