Ultrasound probe, ultrasonic probe and ultrasonic diagnostic device

Abstract

To provide an ultrasonic probing unit capable of obtaining an ultrasonic image having high image quality regardless of a depth in spite of its simple configuration.SOLUTION: An ultrasonic probing unit (1) includes: a packing material (2); a plurality of piezoelectric vibrators (3) formed in an array on a surface of the packing material (2); and an acoustic matching layer (4) disposed on the plurality of piezoelectric vibrators (3). The acoustic matching layer (4) includes a first matching layer (5) in which an ultrasonic wave transmission / reception frequency becomes lower from a central part to both ends in an elevation direction. The first matching layer (5) is formed of a base material (B) in which a plurality of fine particles (G) having the same volume-based median diameter are dispersed from the central part to both ends in the elevation direction, and a degree of dispersion of the fine particles (G) becomes higher from the central part to both ends in the elevation direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasound probe, an ultrasound probe having the ultrasound probe, and an ultrasound diagnostic apparatus having the ultrasound probe. [Background technology]

[0002] Conventionally, ultrasonic diagnostic devices are known as devices for obtaining images of the inside of a subject. Ultrasonic diagnostic devices generally include an ultrasonic probe equipped with a transducer array in which a plurality of piezoelectric transducers are arranged in the azimuth direction. With this ultrasonic probe in contact with the body surface of the subject, ultrasonic beams are transmitted from the transducer array toward the inside of the subject, and ultrasonic echoes from the subject are received by the transducer array to obtain electrical signals corresponding to the ultrasonic echoes. Furthermore, the ultrasonic diagnostic device electrically processes the obtained electrical signals to generate an ultrasonic image of the subject's corresponding part.

[0003] In recent years, there has been an increasing demand for transmitting high-frequency ultrasound waves, for example, about 12 MHz to 15 MHz, to a subject in order to visualize in high resolution tissues such as muscle structures and nerve bundles located at a depth of about 5 mm to 20 mm from the body surface of the subject in an ultrasound image for more detailed observation. As a method for forming an ultrasound beam having a narrow width in the so-called elevation direction in such a shallow region, for example, as disclosed in Patent Document 1, it is known to use an ultrasound probe in which multiple piezoelectric transducers are also arranged in the elevation direction, and to control the aperture width for transmitting and receiving ultrasound in the elevation direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-278918 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, as disclosed in Patent Document 1, when an ultrasonic probe in which multiple piezoelectric transducers are arranged in the elevation direction is used and the aperture width for transmitting and receiving ultrasonic waves in the elevation direction is controlled, an ultrasonic beam having a narrow width regardless of depth is formed in both the azimuth and elevation directions, making it possible to obtain ultrasonic images with high image quality regardless of depth. However, there is a problem in that the configuration of the ultrasonic probe becomes complicated and the system for transmitting and receiving ultrasonic waves also becomes complicated.

[0006] The present invention has been made to solve such conventional problems, and has an object to provide an ultrasound probe having a simple configuration yet capable of obtaining ultrasound images of high image quality regardless of depth, an ultrasound probe having such an ultrasound probe, and an ultrasound diagnostic device having such an ultrasound probe. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the ultrasonic probe of the present invention comprises a backing material, a plurality of piezoelectric transducers arranged on the surface of the backing material, and an acoustic matching layer arranged on the plurality of piezoelectric transducers, the acoustic matching layer including a first matching layer in which the transmission and reception frequency of ultrasonic waves decreases from the center to both ends in the elevation direction, the first matching layer being formed from a base material in which a plurality of microparticles having the same volume-based median diameter are dispersed from the center to both ends in the elevation direction, and the degree of dispersion of the microparticles increases from the center to both ends in the elevation direction.

[0008] The first matching layer has a matching portion for the high frequency range located in the center in the elevation direction and a matching portion for the low frequency range located at both ends in the elevation direction, and it is preferable that the length in the elevation direction of the matching portion for the high frequency range is longer than half the total length in the elevation direction of the first matching layer. It is also preferable that the number of particles per unit volume in the first matching layer be the same from the center to both ends in the elevation direction.

[0009] The first matching layer may have a multi-layer structure made up of a plurality of layers having different acoustic impedances. The acoustic matching layer may also include a second matching layer that is disposed on the surface of the first matching layer opposite the plurality of piezoelectric transducers and is made of a material that is uniform in the elevation direction.

[0010] The fine particles preferably have a volume-based median diameter of 0.01 μm or more and 100.00 μm or less, and more preferably have a volume-based median diameter of 1.00 μm or more and 10.00 μm or less. The particulates may also be made of iron, tungsten, alumina, zirconia or silica.

[0011] The ultrasonic probe according to the present invention is characterized by having the ultrasonic probe according to the present invention. The ultrasonic diagnostic apparatus according to the present invention is characterized by having the ultrasonic probe according to the present invention. Effect of the Invention

[0012] According to the present invention, an ultrasonic probe comprises a backing material, a plurality of piezoelectric vibrators arranged on the surface of the backing material, and an acoustic matching layer arranged on the plurality of piezoelectric vibrators, the acoustic matching layer including a first matching layer in which the transmission and reception frequency of ultrasonic waves decreases from the center to both ends in the elevation direction, and the first matching layer is formed from a base material in which a plurality of microparticles having the same volume-based median diameter are dispersed from the center to both ends in the elevation direction, and the degree of dispersion of the microparticles increases from the center to both ends in the elevation direction, so that despite the simple configuration, ultrasonic images of high image quality can be obtained regardless of depth. [Brief description of the drawings]

[0013] [Figure 1]1 is a perspective view of an ultrasound probe according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view of an ultrasonic probe according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing a matching layer member for a high frequency range and a matching layer member for a low frequency range that form a first matching layer in the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing a first matching layer in the first embodiment of the present invention. [Diagram 5] FIG. 1 is a diagram showing a laminate in which a backing material, a piezoelectric vibrator, a first acoustic matching layer, a second acoustic matching layer, and an extraction electrode are attached to one another in the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing a state in which a flexible printed circuit board is soldered to an extraction electrode of the laminate in the first embodiment of the present invention. [Figure 7] 1 is a block diagram showing a configuration of an ultrasound diagnostic apparatus having an ultrasound probe according to a first embodiment of the present invention. [Figure 8] 1 is a block diagram showing an internal configuration of a transmission / reception circuit according to a first embodiment of the present invention. [Figure 9] 2 is a block diagram showing an internal configuration of an image generating unit according to the first embodiment of the present invention. FIG. [Figure 10] FIG. 11 is a cross-sectional view of an ultrasonic probe according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view of an ultrasonic probe according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following description of the components will be given based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, the terms "same" and "identical" include a generally acceptable margin of error in the technical field.

[0015] First embodiment 1, an ultrasonic probe 1 according to a first embodiment of the present invention includes a backing material 2, a plurality of piezoelectric transducers 3 arranged on the surface of the backing material 2 at an arrangement pitch P in the azimuth direction, an acoustic matching layer 4 arranged on each of the surfaces of the piezoelectric transducers 3, and an acoustic lens 7 arranged on the surfaces of the plurality of acoustic matching layers 4. Each of the plurality of acoustic matching layers 4 has a first matching layer 5 arranged on the surface of the piezoelectric transducer 3 and a second matching layer 6 arranged on the surface of the first matching layer 5. Separation sections 8 filled with epoxy resin or the like are formed between adjacent piezoelectric transducers 3 and between adjacent acoustic matching layers 4.

[0016] Note that, extraction electrodes (not shown) are connected to the multiple piezoelectric vibrators 3, respectively, and a flexible printed circuit board (not shown) connected to the multiple extraction electrodes is disposed on the side surface of the backing material 2, but is omitted for the sake of explanation. For the sake of explanation, hereinafter, the azimuth direction in which the multiple piezoelectric vibrators 3 and the multiple acoustic matching layers 4 are arranged is called the X direction, the stacking direction of the backing material 2, the piezoelectric vibrators 3, the acoustic matching layer 4, and the acoustic lens 7 is called the Z direction, and the elevation direction perpendicular to the X direction and the Z direction is called the Y direction.

[0017] The piezoelectric vibrator 3 generates ultrasonic waves according to a drive signal supplied from a pulser (not shown) or the like connected to the ultrasonic probe 1, and receives ultrasonic echoes and outputs a signal based on the ultrasonic echoes. The piezoelectric vibrator 3 is configured by forming electrodes on both ends of a piezoelectric body made of, for example, piezoelectric ceramics such as PZT (Lead Zirconate Titanate), polymeric piezoelectric elements such as PVDF (Poly Vinylidene Di Fluoride), and piezoelectric single crystals such as PMN-PT (Lead Magnesium Niobate-Lead Titanate).

[0018] The backing material 2 supports the plurality of piezoelectric vibrators 3 and absorbs ultrasonic waves emitted from the plurality of piezoelectric vibrators 3 and propagating backward. The backing material 2 is formed of a rubber material such as ferrite rubber, for example. The acoustic lens 7 is made of a resin material such as epoxy resin, acrylic resin, or polymethylpentene resin, or a rubber material such as silicone rubber.

[0019] The acoustic matching layer 4 is for matching the acoustic impedance between the object in contact with the ultrasonic probe 1 and the piezoelectric transducer 3, so that ultrasonic waves can be easily incident into the object. In general, the acoustic impedance of the piezoelectric transducer 3 is often higher than the acoustic impedance of the acoustic lens 7 and the object, so that the acoustic matching layer 4 can be formed of a material having an acoustic impedance lower than that of the piezoelectric transducer 3 and higher than that of the acoustic lens and the object. In addition, the first matching layer 5 included in the acoustic matching layer 4 preferably has a thickness of about a quarter of the wavelength of the ultrasonic waves propagating through the first matching layer 5 in order to resonate the ultrasonic waves emitted from the piezoelectric transducer 3 and propagating through the first matching layer 5 to enhance the strength of the ultrasonic waves. Similarly, the second matching layer 6 preferably has a thickness of about a quarter of the wavelength of the ultrasonic waves propagating through the second matching layer 6.

[0020] The second matching layer 6 of the acoustic matching layer 4 is formed on the surface of the first matching layer 5, is made of a material that is uniform in the Y direction, and has an acoustic impedance lower than that of the first matching layer 5. For example, the material of the second matching layer 6 can be a resin material such as an epoxy resin or a urethane resin.

[0021] As shown in FIG. 2, the first matching layer 5 of the acoustic matching layer 4 is made of a base material B in which a plurality of fine particles G are dispersed. The base material B of the first matching layer 5 is made of a resin material such as an epoxy resin or a urethane resin. The fine particles G are made of metal or ceramics, and examples of the material used include iron, tungsten, alumina, zirconia, silica, etc. In order to reduce attenuation of ultrasonic waves in the first matching layer 5, the fine particles G preferably have a diameter of 0.01 μm or more and 100.00 μm or less, and more preferably have a diameter of 1.00 μm or more and 10.00 μm or less.

[0022] In addition, in the first matching layer 5, the dispersion of the particles G increases from the center to both ends in the Y direction, and the number of particles G per unit volume in the first matching layer 5 is the same from the center to both ends in the Y direction. Here, the dispersion of the particles G is an index that indicates the variation in the distance between adjacent particles G in the base material B, and the more uniformly the positions of the particles G in the base material B are distributed, the higher the dispersion, and the more locally the particles G are close to each other and the more non-uniformly the positions of the particles G in the base material B are distributed, the lower the dispersion. In the example shown in FIG. 2, a high-frequency matching section A1 is formed in the center in the Y direction, where there are many particles G in contact or close proximity to each other, i.e., the dispersion of the particles G is low, and a low-frequency matching section A2 is formed in the center in the Y direction, where there are many particles G separated from each other and the distribution of the positions of the particles G in the base material B is more uniform, i.e., the dispersion of the particles G is high. Here, since the number of particles G per unit volume is the same from the center to both ends in the Y direction of the first matching layer 5, the acoustic impedance of the high frequency range matching portion A1 and the acoustic impedance of the low frequency range are almost the same.

[0023] However, when two materials having different acoustic impedances are in contact with each other and sound waves pass through the boundary between the materials, the phase of the sound waves is affected, and the group velocity in the propagation direction of the sound waves at the boundary between the two materials is known to be low. As shown in Fig. 2, in the high frequency matching section A1 of the first matching layer 5, since there are many particles G in contact or close to each other, the total amount of effective interfaces between the base material B and the particles G on the propagation path of the ultrasonic waves traveling in the Z direction in the first matching layer 5 is relatively small, while in the low frequency matching section A2, since a plurality of particles G are more uniformly distributed, the total amount of effective interfaces between the base material B and the particles G on the propagation path of the ultrasonic waves traveling in the Z direction in the first matching layer 5 is relatively large. Therefore, for example, the group velocity in the Z direction of the ultrasonic waves propagating from the piezoelectric vibrator 3 to the acoustic lens 7 side in the first matching layer 5 is relatively high in the high frequency matching section A1 and relatively low in the low frequency matching section A2.

[0024] Here, the relationship V=F×W is known, where V is the group velocity of the sound wave, F is the frequency, and W is the wavelength. Because ultrasonic waves having a certain wavelength W are intensified due to the resonance condition caused by the thickness of the first matching layer 5, if the wavelength W is constant, it can be seen that the group velocity of ultrasonic waves propagating through the high frequency range matching portion A1 of the first matching layer 5 is relatively fast, so that the frequency F is high, and the group velocity of ultrasonic waves propagating through the low frequency range matching portion A2 is relatively slow, so that the frequency F is low.

[0025] Moreover, since the high frequency range matching portion A1 is disposed at the center in the Y direction of the acoustic matching layer 4, it has a relatively narrow opening width compared to the overall width in the Y direction of the acoustic matching layer 4. On the other hand, the low frequency range matching portion A2 is disposed at both ends in the Y direction of the acoustic matching layer 4, so it has a relatively wide opening width. Therefore, the width in the Y direction of the ultrasonic beam formed by converging the ultrasonic waves transmitted through the high frequency range matching portion A1 by the acoustic lens 7 becomes relatively narrow, and the width in the Y direction of the ultrasonic beam formed by converging the ultrasonic waves transmitted through the low frequency range matching portion A2 by the acoustic lens 7 becomes relatively wide.

[0026] In general, the higher the frequency of the ultrasonic beam, the higher the image quality of the ultrasonic image can be obtained. However, it is known that the ultrasonic beam is more likely to attenuate, and the lower the frequency of the ultrasonic beam, the less likely the ultrasonic beam is to attenuate. Therefore, in shallow areas within the subject, ultrasound images with high image quality can be obtained due to ultrasound beams that have a relatively high frequency and a narrow width in the Y direction, and in deep areas within the subject, ultrasound images with high image quality can be obtained due to ultrasound beams that have a relatively low frequency and a wide width in the Y direction.

[0027] Here, as a conventional method for adjusting the width of the ultrasonic beam in the Y direction according to the depth, a method is known in which a plurality of piezoelectric transducers are arranged in the Y direction as well, and the aperture width for transmitting and receiving ultrasonic waves in the Y direction is controlled by selecting a plurality of piezoelectric transducers to be used in the Y direction. However, this method has a problem in that the configuration of the ultrasonic probe becomes complicated, and the control of the system for transmitting and receiving ultrasonic waves also becomes complicated. According to the ultrasound probe 1 according to the first embodiment of the present invention, it is possible to obtain ultrasound images with high image quality regardless of the depth, while having a simple configuration.

[0028] Next, a method for manufacturing the first matching layer 5, which is a characteristic member of the ultrasonic probe 1 according to the first embodiment of the present invention, will be described. First, the fine particles G made of iron, tungsten, alumina, zirconia, silica, or the like are subjected to a surface treatment.

[0029] Examples of surface treatments for the fine particles G include oil treatments using hydrocarbon oils, ester oils, lanolin, etc., silicone treatments using dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, etc., fluorine compound treatments using perfluoroalkyl group-containing esters, perfluoroalkylsilanes, perfluoropolyethers, and polymers having perfluoroalkyl groups, silane coupling agent treatments using 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, etc., titanium coupling agent treatments using isopropyltriisostearoyltitanate, isopropyltris(dioctylpyrophosphate)titanate, etc., metal soap treatments, amino acid treatments using acylglutamic acid, etc., lecithin treatments using hydrogenated egg yolk lecithin, etc., collagen treatments, polyethylene treatments, moisture retention treatments, inorganic compound treatments, mechanochemical treatments, and phosphoric acid compound treatments using phosphoric acid, phosphorous acid, phosphates, phosphites, etc. are used. Among these, from the viewpoint of controlling the dispersibility of the fine particles G, it is preferable to carry out phosphoric acid compound treatments.

[0030] At this time, fine particles G for a high frequency range with a large degree of surface treatment and fine particles G for a low frequency range with a small degree of surface treatment are obtained. For example, even when the same surface treatment agent is used, the more the amount of the surface treatment agent is increased during the surface treatment, the more fine particles G with a high degree of dispersion in the base material B can be obtained, and the less the amount of the surface treatment agent is decreased, the more fine particles G with a low degree of dispersion in the base material B can be obtained. Also, for example, the more the number of times of surface treatment is performed, the more fine particles G with a high degree of dispersion in the base material B can be obtained, and the less the number of times of surface treatment is performed, the more fine particles G with a low degree of dispersion in the base material B can be obtained.

[0031] Here, in order to reduce the attenuation of the ultrasonic waves emitted from the piezoelectric vibrator 3 and propagating through the first matching layer 5, the fine particles G preferably have a diameter of 0.01 μm or more and 100.00 μm or less, and more preferably have a diameter of 1.00 μm or more and 10.00 μm or less, and the diameter of the fine particles G can be measured as follows. First, the fine particles G that have been sufficiently surface-treated are added to methanol so as to be 0.5 mass %, and are subjected to ultrasonic waves for 10 minutes to disperse the fine particles G in methanol. The particle size distribution of the fine particles G dispersed in methanol in this way is measured by a laser analysis scattering type particle size distribution measuring device (manufactured by Horiba, Ltd., product name: LA950V2), and the diameter of the fine particles G can be obtained by calculating the volume-based median diameter based on the measured particle size distribution. The volume-based median diameter in this case is the particle diameter equivalent to 50% of the cumulative distribution when the particle size distribution is expressed as a cumulative distribution.

[0032] Next, a resin material that hardens when heated, such as epoxy resin or urethane resin, is prepared as the base material B, and fine particles G for the high frequency range are added to the resin material before hardening, and the resin material and the fine particles G for the high frequency range are mixed by a so-called planetary mixer or the like to obtain a mixture for the high frequency range. Fine particles G for the low frequency range are added to the resin material before hardening, and the resin material and the fine particles G for the low frequency range are mixed by a planetary mixer or the like to obtain a mixture for the low frequency range. The mixture for the high frequency range before hardening and the mixture for the low frequency range before hardening obtained in this way are each heated and hardened, and the mixture after hardening is molded into a plate shape, thereby obtaining a matching member M1 for the high frequency range and a matching member M2 for the low frequency range as shown in FIG. 3. When the mixture after hardening is molded into a plate shape, grinding and dicing by a so-called dicing saw or the like are performed.

[0033] Furthermore, by using an adhesive such as an epoxy adhesive to bond the low frequency range matching member M2 to both ends of the obtained high frequency range matching member M1 as shown in Fig. 3, the first matching layer 5 as shown in Fig. 4 is obtained. The high frequency range matching member M1 corresponds to the high frequency range matching section A1, and the low frequency range matching member M2 corresponds to the low frequency range matching section A2. The first matching layer 5 obtained in this manner is polished to a desired thickness, such as a thickness of a quarter of the wavelength of the ultrasonic wave propagating through the first matching layer 5.

[0034] Next, a method for manufacturing the ultrasonic probe 1 according to the first embodiment of the present invention will be described. 5, a piezoelectric vibrator 3 electrically connected to lead wires 9 is attached to a backing material 2, a first matching layer 5 is attached onto the piezoelectric vibrator 3, and a second matching layer 6 is attached onto the first matching layer 5. In this state, a dicing saw or the like is used to cut the piezoelectric vibrator 3, the first matching layer 5, and the second matching layer 6 together along the YZ plane, thereby dividing the piezoelectric vibrator 3, the first matching layer 5, and the second matching layer 6 into a plurality of pieces. As a result, the plurality of pieces of the piezoelectric vibrator 3, the first matching layer 5, and the second matching layer 6 are arranged along the X direction.

[0035] Here, the first matching layer 5 is formed by bonding the high frequency region matching member M1 and the low frequency region matching member M2 together, but since the high frequency region matching member M1 and the low frequency region matching member M2 are made of the same material, when the first matching layer 5 is cut, damage to the dicing saw or the like is unlikely to occur, and the dicing quality can be improved. In particular, in order to generate ultrasonic waves with a high frequency of about 12 MHz to 15 MHz, it is necessary to perform a precise cutting process so that the arrangement pitch P of the piezoelectric vibrators 3 is very short, but even in such a case, the piezoelectric vibrators 3, the first matching layer 5, and the second matching layer 6 can be easily cut at the short arrangement pitch P.

[0036] When the piezoelectric vibrator 3, the first matching layer 5, and the second matching layer 6 are cut in this manner, the spaces between the piezoelectric vibrators 3, the first matching layer 5, and the second matching layer 6 adjacent to each other in the X direction are filled with a filler such as epoxy resin, thereby forming the separation portion 8 shown in Figure 1.

[0037] Next, as shown in Fig. 6, a flexible printed circuit (FPC) 10 is attached to the side surface of the backing material 2 in the Y direction, and the flexible printed circuit 10 and the lead-out wiring 9 led out from the piezoelectric vibrator 3 are electrically connected to each other. In the example shown in Fig. 6, the flexible printed circuit 10 and the lead-out wiring 9 are electrically connected to each other by solder S. Note that instead of the flexible printed circuit 10, a printed circuit board (PCB) can also be disposed on the side surface of the backing material 2 in the Y direction. Finally, an acoustic lens 7 is attached onto the second matching layer 6, thereby completing the manufacture of the ultrasonic probe 1 as shown in FIG.

[0038] Next, an ultrasonic diagnostic device having an ultrasonic probe 1 according to the first embodiment of the present invention will be described. As shown in Fig. 7, in an ultrasonic diagnostic device 11, a transmitting / receiving circuit 12, an image generating unit 13, a display control unit 14, and a monitor 15 are successively connected to the ultrasonic probe 1. A device control unit 16 is connected to the transmitting / receiving circuit 12, the image generating unit 13, and the display control unit 14. An input device 17 is connected to the device control unit 16. A memory (not shown) is also connected to the device control unit 16. The ultrasonic diagnostic device 11 also includes an ultrasonic probe 21 including the ultrasonic probe 1 and a transmission / reception circuit 12. The image generation unit 13, the display control unit 14, and the device control unit 16 constitute a processor 22 for the ultrasonic diagnostic device 11.

[0039] The transmission / reception circuit 12, under the control of the device control unit 16, transmits ultrasonic waves from the ultrasonic probe 1 and generates a sound ray signal based on a reception signal acquired by the ultrasonic probe 1. As shown in Fig. 8, the transmission / reception circuit 12 has a pulser 23 connected to the ultrasonic probe 1, and an amplifier 24, an AD (Analog Digital) converter 25, a filter circuit 26, and a beamformer 27, which are connected in series from the ultrasonic probe 1 in this order.

[0040] The pulser 23 includes, for example, a plurality of pulse generators, and adjusts the delay amount of each drive signal and supplies it to the plurality of piezoelectric transducers 3 based on a transmission delay pattern selected in response to a control signal from the device control unit 16 so that ultrasonic waves transmitted from the plurality of piezoelectric transducers 3 of the ultrasonic probe 1 form an ultrasonic beam. In this way, when a pulsed or continuous wave voltage is applied to the electrodes of the piezoelectric transducers 3, the piezoelectric transducers 3 expand and contract, and each piezoelectric transducer 3 generates a pulsed or continuous wave ultrasonic wave, and an ultrasonic beam is formed from a composite wave of these ultrasonic waves.

[0041] The transmitted ultrasonic beam is reflected, for example, by tissue in the subject, and propagates toward the ultrasonic probe 1 of the ultrasonic probe 21. Each piezoelectric transducer 3 of the ultrasonic probe 1 expands and contracts upon receiving the ultrasonic echo propagating toward the ultrasonic probe 1 in this manner, generating received signals that are electrical signals, and outputs these received signals to the amplifier 24.

[0042] The amplifier 24 amplifies the signals input from each piezoelectric transducer 3 of the ultrasonic probe 1 and transmits the amplified signals to the AD converter 25. The AD converter 25 converts the signals transmitted from the amplifier 24 into digital reception data and transmits the reception data to the filter circuit 26. The filter circuit 26 includes a so-called low-pass filter and a high-pass filter, and cuts low-frequency component signals below a set lower limit in areas shallower than the focal depth of the ultrasonic beam, and cuts high-frequency component signals above a set upper limit in areas deeper than the focal depth of the ultrasonic beam. This eliminates signals with a low S / N ratio (signal / noise ratio).

[0043] The reception data filtered by the filter circuit 26 is transmitted to the beamformer 27. The beamformer 27 performs so-called reception focusing processing by adding each of the reception data filtered by the filter circuit 26 with a delay in accordance with the sound speed or sound speed distribution set based on the reception delay pattern selected in response to a control signal from the device control unit 16. By this reception focusing processing, each of the reception data converted by the AD conversion unit 25 is phased and added, and a sound ray signal in which the focus of the ultrasonic echo is narrowed is acquired.

[0044] As shown in FIG. 9, the image generating unit 13 has a configuration in which a signal processing unit 28, a DSC (Digital Scan Converter) 29, and an image processing unit 30 are connected in series. The signal processing unit 28 performs correction for attenuation due to distance on the sound ray signals generated by the beamformer 27 of the transmission / reception circuit 12 in accordance with the depth of the ultrasonic reflection position, and then performs envelope detection processing to generate a B-mode image signal, which is tomographic image information regarding the tissue in the subject.

[0045] The DSC 29 converts (raster converts) the B-mode image signal generated by the signal processing unit 28 into an image signal that conforms to the scanning method of a normal television signal. The image processing unit 30 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 29, and then outputs the B-mode image signal to the display control unit 14. In the present invention, the B-mode image signal that has been subjected to image processing by the image processing unit 30 is simply called an ultrasound image.

[0046] Under the control of the device control unit 16, the display control unit 14 performs predetermined processing on the ultrasound image generated by the image generation unit 13 and displays the ultrasound image on the monitor 15. The monitor 15 displays the ultrasound image generated by the image generation unit 13 under the control of the display control unit 14, and includes, for example, a display device such as an LCD (Liquid Crystal Display) or an organic EL display (Organic Electroluminescence Display).

[0047] The device control unit 16 controls each part of the ultrasonic diagnostic device 11 based on a control program stored in advance. The input device 17 is used by the user to perform input operations, and can be configured with a keyboard, a mouse, a trackball, a touch pad, a touch panel, and the like.

[0048] Although not shown, a memory connected to the device control unit 16 stores the control program of the ultrasonic diagnostic device 11 and the like. As the memory, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), a flexible disk (FD), a magneto-optical disk (MO disk), a magnetic tape (MT), a random access memory (RAM), a compact disk (CD), a digital versatile disk (DVD), a secure digital card (SD card), a universal serial bus memory (USB memory), or other recording media, or a server, etc., can be used.

[0049] The processor 22 having the image generation unit 13, the display control unit 14 and the device control unit 16 is composed of a CPU (Central Processing Unit) and a control program for causing the CPU to perform various processes, but may also be composed of an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit) or other ICs (Integrated Circuits), or may be composed of a combination of these.

[0050] Furthermore, the image generating section 13, the display control section 14 and the device control section 16 of the processor 22 may be configured as being partially or entirely integrated into a single CPU or the like.

[0051] The ultrasonic diagnostic device 11 in the first embodiment of the present invention includes an ultrasonic probe 1 having an acoustic matching layer 4 in accordance with the first embodiment of the present invention, and therefore can obtain ultrasonic images of high image quality regardless of depth without complex control of the aperture width for transmitting and receiving ultrasonic waves in the elevation direction of the ultrasonic probe 1.

[0052] In the example shown in Figure 2, the matching portion A1 for the high frequency range is arranged in the center of the first matching layer 5 in the Y direction, and the matching portions A2 for the low frequency range are arranged at both ends of the first matching layer 5 in the Y direction, and the length in the Y direction of the matching portion A1 for the high frequency range can be made the same as the length in the Y direction of each of the matching portions A2 for the low frequency range.

[0053] Also, by making the length of the high frequency region matching section A1 in the Y direction longer than the length of the low frequency region matching section A2 in the Y direction, the proportion of ultrasound transmitted and received through the high frequency region matching section A1 can be increased. Although ultrasound with a higher frequency is more likely to attenuate, by making the high frequency region matching section A1 longer in the Y direction, even if ultrasound with a relatively high frequency is attenuated within the subject, the amount of ultrasound echoes received through the high frequency region matching section A1 can be sufficiently secured, and the brightness of ultrasound at a relatively shallow part can be prevented from decreasing. Therefore, ultrasound images with more uniform image quality can be obtained.

[0054] In this case, for example, the length in the Y direction of the high frequency range matching part A1 is preferably longer than half the total length in the Y direction of the first matching layer 5. Specifically, for example, the length in the Y direction of the high frequency range matching part A1 may be twice or three times the length in the Y direction of the low frequency range matching part A2.

[0055] In addition, the dispersion degree of the fine particles G in the base material B in the first matching layer 5 is adjusted by performing a surface treatment on the fine particles G, but the method of adjusting the dispersion degree of the fine particles G is not limited to the surface treatment. For example, the dispersion degree of the fine particles G in the base material B can be changed by changing the method of mechanically mixing the fine particles G in the base material B. For example, by mixing the fine particles G in the base material B using a so-called propeller mixer, the dispersion degree of the fine particles G can be lowered compared to the case of mixing the fine particles G using a planetary mixer. Therefore, when preparing a mixture for a high frequency range, the fine particles G can be mixed in the base material B using a propeller mixer, and when preparing a mixture for a low frequency range, the fine particles G can be mixed in the base material B using a planetary mixer. In addition, for example, the dispersion degree of the particles G can also be changed by changing the time for which the particles G are mixed into the base material B.

[0056] The dispersion degree of the fine particles G can also be changed by changing the time required for hardening the base material B. For example, the dispersion degree of the fine particles G can be reduced by lowering the temperature at which the mixture of the base material B and the fine particles G is heated and the time required for hardening the base material B is increased, whereas the dispersion degree of the fine particles G can be increased by increasing the temperature at which the mixture of the base material B and the fine particles G is heated and the time required for hardening the base material B is decreased.

[0057] Furthermore, although the ultrasound probe 1 has an acoustic lens 7, it is not necessarily required to have the acoustic lens 7 because, for example, the focus of the ultrasound beam emitted from the ultrasound probe 1 can be adjusted by the transmission / reception circuit 12 of the ultrasound diagnostic device 11.

[0058] In addition, the filter circuit 26 of the transmission / reception circuit 12 is described as cutting off high-frequency component signals above a set upper limit at a depth deeper than the focal depth of the ultrasonic beam, but it is also possible to gradually cut off high-frequency component signals so that the ratio of low-frequency component signals gradually increases as the depth increases. This makes it possible to obtain ultrasonic images with higher image quality regardless of the depth.

[0059] Embodiment 2 In embodiment 1, an example is described in which the first matching layer 5 is composed of two types of regions, a matching portion A1 for the high frequency range and a matching portion A2 for the low frequency range. However, the first matching layer 5 can also be composed of three or more types of regions with different dispersion degrees of the microparticles G, so long as the dispersion degree of the microparticles G in the base material B increases from the center toward both ends in the Y direction so that the transmission and reception frequency of the ultrasonic waves decreases from the center toward both ends in the Y direction.

[0060] As shown in Fig. 10, an ultrasonic probe 1A according to the second embodiment of the present invention includes an acoustic matching layer 4A instead of the acoustic matching layer 4 in the ultrasonic probe 1 according to the first embodiment shown in Figs. 1 and 2. The acoustic matching layer 4A has a first matching layer 5A instead of the first matching layer 5 in the acoustic matching layer 4 in the first embodiment. The first matching layer 5A has a first frequency range matching part A3 in the center in the Y direction, a second frequency range matching part A4 adjacent to both ends in the Y direction of the first frequency range matching part A3, and a third frequency range matching part A5 located at both ends in the Y direction of the first matching layer 5A.

[0061] The dispersion degree of the fine particles G in the base material B is the lowest in the first frequency range matching portion A3, the second lowest in the second frequency range matching portion A4, and the highest in the third frequency range matching portion A5, so that the ultrasonic waves transmitted through the first frequency range matching portion A3 have the highest frequency, the second highest in the second frequency range matching portion A4, and the lowest in the third frequency range matching portion A5. In addition, since the first frequency range matching portion A3 is located in the center of the first matching layer 5A in the Y direction, the second frequency range matching portion A4 is adjacent to both ends of the first frequency range matching portion A3 in the Y direction, and the third frequency range matching portion A5 is located at both ends of the first matching layer 5A in the Y direction, the opening width for transmitting and receiving ultrasonic waves is the narrowest in the first frequency range matching portion A3, the second narrowest in the second frequency range matching portion A4, and the widest in the third frequency range matching portion A5. Therefore, the width in the Y direction of the ultrasonic beam formed when the ultrasonic waves that have passed through each matching section are converged by the acoustic lens 7 is such that the ultrasonic beam that passes through the first frequency range matching section A3 is the narrowest, the ultrasonic beam that passes through the second frequency range matching section A4 is the next narrowest, and the ultrasonic beam that passes through the third frequency range matching section A5 is the widest.

[0062] Since ultrasonic beams with higher frequencies are more likely to attenuate within the subject, in relatively shallow regions, ultrasonic images are formed mainly by ultrasonic beams with high frequencies, in medium depth regions, ultrasonic images are formed mainly by ultrasonic beams with medium frequencies, and in relatively deep regions, ultrasonic images are formed mainly by ultrasonic beams with low frequencies. Therefore, the ultrasound probe 1A according to the second embodiment of the present invention has a simple configuration and yet can obtain ultrasound images with higher image quality regardless of the depth.

[0063] 10 shows an example in which the first matching layer 5A is composed of three types of regions, the first frequency range matching section A3, the second frequency range matching section A4, and the third frequency range matching section A5, but the first matching layer 5A can also be composed of four or more types of regions with different dispersion degrees of the particles G. The first matching layer 5A can also be configured so that the dispersion degree of the particles G in the base material B increases continuously from the center to both ends in the Y direction of the first matching layer 5A. This makes it possible to obtain ultrasonic images with more uniform image quality.

[0064] Although not shown, an ultrasonic probe including the ultrasonic probe 1A according to the second embodiment can be configured in a manner similar to the ultrasonic probe 21 of the first embodiment, and further, an ultrasonic diagnostic device including this ultrasonic probe can be configured in a manner similar to the ultrasonic diagnostic device 11 of the first embodiment.

[0065] Third embodiment In the first embodiment, the first matching layer 5 is made up of one layer, but it may also be made up of a plurality of layers. As shown in Fig. 11, an ultrasonic probe 1B according to the third embodiment of the present invention includes an acoustic matching layer 4B instead of the acoustic matching layer 4 in the ultrasonic probe 1 of the first embodiment shown in Fig. 1 and Fig. 2. Also, the acoustic matching layer 4B has a first matching layer 5B instead of the first matching layer 5 in the acoustic matching layer 4 in the first embodiment. The first matching layer 5B has a transducer-side first matching layer 31A arranged on the piezoelectric transducer 3 side, and a lens-side first matching layer 31B arranged on the acoustic lens 7 side.

[0066] The transducer-side first matching layer 31A and the lens-side first matching layer 31B have a high-frequency region matching section A1 arranged in the center of the first matching layer 5B in the Y direction and a low-frequency region matching section A2 arranged at both ends of the first matching layer 5B in the Y direction, similar to the first matching layer 5 in the first embodiment. The transducer-side first matching layer 31A and the lens-side first matching layer 31B each contain the same base material B and particles G. However, the number of particles G contained per unit volume in the base material B is greater in the transducer-side first matching layer 31A than in the lens-side first matching layer 31B. As a result, the transducer-side first matching layer 31A has a higher acoustic impedance than the lens-side first matching layer 31B.

[0067] In this way, the first matching layer 5B has a multi-layer structure consisting of a plurality of layers having different acoustic impedances, so that the acoustic impedance between the object in contact with the ultrasonic probe 1B and the piezoelectric transducer 3 can be matched with high precision, and ultrasonic waves can be more easily incident into the object. In addition, since the same base material B is used for the transducer-side first matching layer 31A and the lens-side first matching layer 31B, for example, when the piezoelectric transducer 3 and the acoustic matching layer 4B are cut by a dicing saw or the like in the manufacturing process of the ultrasonic probe 1B, damage to the dicing saw or the like is unlikely to occur, and the quality of dicing can be improved. In particular, in order to generate ultrasonic waves with a high frequency of about 12 MHz to 15 MHz, it is necessary to perform a precise cutting process so that the arrangement pitch P of the piezoelectric transducer 3 is very short, but even in such a case, the piezoelectric transducer 3 and the acoustic matching layer 4B can be easily cut at a short arrangement pitch P.

[0068] It is also possible to use a base material B having a relatively high acoustic impedance for the transducer-side first matching layer 31A, and a base material B having a relatively low acoustic impedance for the lens-side first matching layer 31B. Even in this case, the acoustic impedance between the subject in contact with the ultrasonic probe 1B and the piezoelectric transducer 3 can be matched with high precision, making it easier to introduce ultrasonic waves into the subject.

[0069] 11, the first matching layer 5B is composed of two layers, the transducer-side first matching layer 31A and the lens-side first matching layer 31B, but the first matching layer 5B may be composed of, for example, three or more layers having different acoustic impedances. This allows the acoustic impedance between the object in contact with the ultrasonic probe 1B and the piezoelectric transducer 3 to be matched with even greater precision, making it easier to introduce ultrasonic waves into the object.

[0070] Although not shown, an ultrasonic probe including the ultrasonic probe 1B according to the third embodiment can be configured in a manner similar to the ultrasonic probe 21 of the first embodiment, and further, an ultrasonic diagnostic device including this ultrasonic probe can be configured in a manner similar to the ultrasonic diagnostic device 11 of the first embodiment. Also, although the aspects of the third embodiment are shown to be applied to the first embodiment, they can be similarly applied to the second embodiment. [Explanation of symbols]

[0071] 1,1A ultrasonic probe, 2 backing material, 3 piezoelectric transducer, 4,4A,4B acoustic matching layer, 5,5A,5B first matching layer, 6 second matching layer, 7 acoustic lens, 8 separation section, 9 lead wiring, 10 flexible printed circuit board, 11 ultrasonic diagnostic device, 12 transmission / reception circuit, 13 image generation section, 14 display control section, 15 monitor, 16 device control section, 17 input device, 21 ultrasonic probe, 22 processor, 23 pulser, 24 amplifier section, 25 AD conversion section, 26 filter circuit, 27 beamformer, 28 signal processing section, 29 DSC, 30 image processing section, 31A transducer side first matching layer, 31B lens side first matching layer, A1 high frequency region matching section, A2 low frequency region matching section, A3 first frequency region matching section, A4 second frequency region matching section, A5 Matching part for the third frequency range, B base material, G fine particles, M1 matching material for the high frequency range, M2 matching material for the low frequency range, P array pitch, S solder.

Claims

1. A backing material; A plurality of piezoelectric vibrators arranged on a surface of the backing material; an acoustic matching layer disposed on the plurality of piezoelectric transducers; Equipped with the acoustic matching layer includes a first matching layer having an ultrasonic transmission / reception frequency that decreases from a center portion toward both ends in an elevation direction; The first matching layer is formed from a base material in which a plurality of microparticles having the same volume-based median diameter are dispersed from the center to both ends in the elevation direction, and the degree of dispersion of the microparticles increases from the center to both ends in the elevation direction.

2. the first matching layer has a matching portion for a high frequency range disposed at a center portion in the elevation direction and a matching portion for a low frequency range disposed at both ends in the elevation direction, 2. The ultrasonic probe according to claim 1, wherein the length of the high frequency region matching portion in the elevation direction is more than half the total length of the first matching layer in the elevation direction.

3. 3. The ultrasonic probe according to claim 1, wherein the number of said particles per unit volume in said first matching layer is the same from the center to both ends in said elevation direction.

4. 4. The ultrasonic probe according to claim 1, wherein the first matching layer has a multi-layer structure made up of a plurality of layers having different acoustic impedances.

5. The ultrasonic probe according to any one of claims 1 to 4, wherein the acoustic matching layer includes a second matching layer arranged on a surface of the first matching layer opposite the plurality of piezoelectric transducers and made of a material that is uniform in the elevation direction.

6. 6. The ultrasonic probe according to claim 1, wherein the fine particles have a volume-based median diameter of 0.01 μm or more and 100.00 μm or less.

7. The ultrasonic probe according to claim 6 , wherein the fine particles have a volume-based median diameter of 1.00 μm or more and 10.00 μm or less.

8. 8. The ultrasonic probe according to claim 1, wherein the fine particles are made of iron, tungsten, alumina, zirconia or silica.

9. An ultrasonic probe comprising the ultrasonic probe according to any one of claims 1 to 8.

10. An ultrasonic diagnostic apparatus comprising the ultrasonic probe according to claim 9.

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