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JPS5917338

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DESCRIPTION JPS5917338
[0001]
The present invention relates to an ultrasonic probe for performing transmission and reception
1B of ultrasonic waves in an ultrasonic diagnostic apparatus. Recently, advances in ultrasound
technology have been remarkable, and active research has been conducted on both diagnosis and
treatment in the medical field. The ultrasonic diagnostic method drives the probe in a state in
which the probe having an imaging element, which is an electroacoustic transducer, is brought
into contact with the body surface directly or via an ice bag or the like, and the ultrasonic wave is
extremely short. It radiates into the body intermittently for a time only. At this time, since the
tissue and organs differ in acoustic characteristics (the product of the density of the medium and
the velocity of sound) depending on the type while ultrasound propagates through human tissue,
a part of the ultrasound is generated at the interface of tissues with different intrinsic
impedances. Is reflected back. This ultrasound echo is received by the same probe used at the
time of transmission and processed to obtain one ultrasound tomographic image. An ultrasonic
probe used today for a mechanical scan type ultrasonic diagnostic apparatus will be described
with reference to FIG. In the figure, reference numeral 1 denotes a piezoelectric imaging element,
on the surface of which a plate electrode of this piezoelectric vibrator l is formed, silver, nickel or
the like is formed on the signal side electrode side ground side IEffi using means such as
evaporation. The ? / 4 acoustic matching layer 2 is provided on the ground side electrode side,
and the damping layer 3 is provided on the signal side electrode side. In this probe, it is
preferable that the waveform of the ultrasonic wave received by the probe is a shorter pulse
width, that is, a more wide band '1'. There are two ways to achieve this desirable property in a
hydraulic manner. ? The official 1 is going to be in January for the dumping layer which has a
large and pumping characteristic. This damping 1 ? 3 theoretical sex change makes the sound
impedance equal to the pressure of the 4 ? mover 1 and the reflection at the interface with the
damping 1 ? 3 ? LE r J L & the motor 1 Elimination There are cases where ultrasonic waves
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emitted by the payer are attenuated in the damping layer 3. The acoustic impedance is z = 25 x
106 kg / m- "5ee-as a damping material that satisfies the above conditions, and a tungsten
particle or the like having a ratio of 419.1 to epoxy resin or polyvinyl chloride 11N fat is jfk. The
degree of ultrasonic wave attenuation is about 2 odB per cm of I MHz C. Y ? 2 is to use an
effective lf echo matching layer. The ideal property of this sound 7? matching layer is that the
acoustic impedance of the object is Zp, and the acoustic impedance of the piezoelectric
transducer is Zp. . A wide band, high sensitivity characteristics can be obtained.
At this time, a value such as 2- ', etc. is obtained, 5xl 06x33x106 = 7.03x1 Qs kgm "sec"-', and a
material such as chalcogenide glass such as arsenic sulfide selenide glass is preferred. ? has
been developed, but this material is not suitable for probes that diagnose the human body in
terms of stability and toxicity. Therefore, at present, the material stability and non-toxic
conditions are satisfied. Z = 7.0 x lOa kgm-! It can be said that there is no acoustic matching
material having an acoustic impedance of about 1 sec. Next, in order to obtain an effective sound
#, an ultrasonic probe in which the acoustic matching layer is divided into two layers as shown in
FIG. 2 has been developed. In FIG. 2, 11 is a fused quartz having t'y, '[' 1E imager, 12 has, for
example, an acoustic impedance z, 13xlOs kgm "5ec-", and has a thickness of 174 of the
ultrasonic wavelength. . @ 1 acoustic matching layer, 13 is a second acoustic matching 14
formed, for example, of an epoxy resin of acoustic impedance 22 = 2.9 О I Qa kgm?'SeC ? ?-1
in a thickness dimension of 1?4 of the wavelength of ultrasonic waves 14 .14 is a damping layer
formed by dispersing tungsten powder in an epoxy 1 layer, and 15 is an IE insulator 11. ии g 1
acoustic matching layer 12, ? 2 A gap 16 formed by cutting R ? MP matching layer 13 with a
diamond cutter G) 1? is a silicon lens which is provided in h 1 ii of ? 7 F (1, ? matching layer
13 and makes the ultrasonic beam 14 east. In this case, the ideal properties of the cocoon /
replication layer are as follows: when the agency's 2 и 1S impedance of the subject is 2 ░ и r and
the pressure + 1 loss actuator 11 is y + and-# impedance is Zp и и и 1 Sawa 2. Ift% I impedance z of
the wedge matching layer 12 and the small innocence dance of the second acoustic matching
layer 13. Z / z2 = J Zp / zo, the relationship of 1, i * IA "j-do it? Here, broadband and high
sensitivity 1 ? 1. [You can also get the characteristics-)). For example, the 1st acoustic matching
layer 12 has an impedance of 1 thousand, z = l 3 x 106 kg + n-'5 ec- It is possible to realize in the
layer 13 a probe of a two-layer matching layer type close to an epoxy resin of 11 cps Z2 =
2.9xl06 kgm- "5ee-". However, when an array type probe for sector scan is used in an endoscopic
manner, it is necessary to form the probe in a very small size in order to insert the probe into one
body.
At this time, d: the center interval ? of each transducer element: the wavelength ? of the
ultrasonic wave as a condition for not causing the grating clove to be generated in each
transducer element. : The scanning angle must satisfy the above equation. For example, the
scanning angle ?. ????? When the sound speed of the ultrasonic wave frequency f = 5 MHz
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is set to 1500 m / sec, the wavelength of the ultrasonic wave is ? = 0.3 'mm. When these
numerical values are substituted into the above equation, the pitch of each transducer element
becomes d (0175 plane). Therefore, when the width dimension of the transducer element is
about 0.125 mIn, the gap 15 of each transducer element is 0.175-0.125 = 0.05 mm. As described
above, when the size of the gap between the transducer elements is reduced, in the case where
the vibration segments are divided into 1 by the electrodes as described in FIG. In order to get
bigger, it is impossible to get seven high precision peaks. In order to realize this crosstalk at 30
dB or less, which is usually required, as shown in FIG. 3, the problem is solved by forming a gap
15 between the individual armature elements. A thin diamond cutter is usually used to form the
gap 15. Diamond cutter JJ for precision cutting is usually refined diamond powder, It is dispersed
in an alloy consisting of lead, 11F lead and the like and molded by bonding, or molded by dialmond powder all-resin bonding. The former cutter is suitable for cutting Pz'1 'ceramic, ferrite,
lithium niobate single crystal, gallium phosphorus, gallium arsenide gold and the like. The
original cutter is suitable for cutting fused quartz, -r lumina ceramics, etc. The use of the frontline cutter for cutting fused quartz and glass is very exhaustive, and when forming many caps
like an array-type probe, the width between the first cap and the last gap is different. Not
desirable. On the other hand, it is technically difficult to form a 1-minute cutter to a thickness of
1 mm or less, and it is therefore difficult to form a gap of about 50 ?m as described above. From
the above reasons, fused quartz is considered as an acoustic matching layer for a 5 MHz or
higher sector scan ultrasonic probe, considering the compatibility between the diamond cutter
and the material to be cut. The processability becomes a problem. From this, the acoustic
matching material of 10 to 20 X I Qe kgm- "5ec-" is suitable for the two-layer matching layer
type joint, and the acoustic impedance is 7 to 10 X 110 X 10 for the single-matching layer type.
An acoustic matching material of 'sec 1 is desired.
The present invention has been made in view of the above problems. In an ultrasonic probe
composed of a piezoelectric imaging moving member, a damping layer, and an acoustic matching
layer, the acoustic matching having a single crystal (by forming a sound R matching layer using
A, the sensitivity is large and the bandwidth is It is an object of the present invention to provide a
wide and easily processed ultrasonic probe. Although one embodiment of the present invention
will be described below with reference to the drawings, the present invention effectively utilizes a
custom-made material, so the basic structure is the same as that of a conventional probe. For this
reason, FIG. 2 and FIG. 3 will be used together in the explanation, and the same reference
numerals will be appended to the same reference numerals in the same part of the explanation to
distinguish them from the conventional example. In FIG. 2, 11 'is a PzTIE electro-oscillator, and a
single crystal material such as silver chloride (AgCe) of acoustic impedance Z1 = 33.times.1611
kgm'5 eC- is used at an ultrasonic wavelength .lambda. A C41 acoustic matching layer 12 'is
formed to a thickness of 1/4. Further, an epoxy resin of H1 intensity z = 4.2 О 10 9 kgrn 'sec' is
formed in the first acoustic matching layer 12 'in a method of an ultrasonic wavelength ? и 1?4
I)'> thickness ? 1 method. The acoustic matching layer 13 'is installed. Then, a damping layer 14
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'formed by dispersing tungsten powder or the like in an epoxy resin is provided on the plate
surface of the piezoelectric vibrator 11' on the 11II side. Here, as shown in FIG. 3, a pressurecontrolled wicking element 11 'and a first acoustic matching layer 12'. @@ 22 acoustical layer 13
'is cut at equal intervals under the condition satisfying the above equation to form cap 15'. Next,
a silicon lens 16 'is provided to focus the ultrasound beam on top of the second sound-I4
alignment + 413'. Table 1 shows the characteristics of each material used in this example. Table
1 Next, an AgCe substantially crystal having a base salt type crystal structure and blue and
belonging to an equiaxed crystal system will be described. This AgCz single crystal is prepared by
putting high purity Ag and high purity AgC / 1 formed from ti2 h into powder in a glass crucible
and drying well, and the temperature is 1 ░ C above melting point 458 ░ C and the lower
portion is below melting point It is obtained by lowering at a speed of several rrm / hr in a sloped
post furnace. The crystal axis of the single crystal thus obtained is determined by the X-ray Lawe
method, mounted on a goniometer, and cut along the target crystal plane to form the brush 1
acoustic matching layer 12 '. Here, the reason why the C crystal plane is made clear is that the
velocity of one wave per hundred of a single crystal is different depending on the direction with
respect to the crystal axis.
In the case of AgCl, the transfer speed when the longitudinal wave propagates in the <100>
direction of the crystal is 3276 rrV s e c, but in (110> direction, it becomes 2900 nl / See. By this
two-layer U-layer type bonding, as described above, by satisfying the 2 ░ / 22 = 2 relationship.
Wide band and high sensitivity characteristics can be obtained. In addition, the matching effect
can be made the best by setting the thickness of each of the ridges 12 'and 13' to 1 / 4?.
Therefore, to meet this condition, the first sound II j I matching /! ????????? When an
epoxy resin is used for the second sound and the second sound 413 ', Z, / Z, = 18.3 x 10' / 4.2 x
1011 = 4.36. This value is the acoustic impedance zp of the piezoelectric vibrator 11 '= 3. '(Xlo *
kgm-5 ee-', acoustic impedance of the subject ZOT = 1.5 x 106 kgm 'Sec' assumed J's 7 stone) T =
33 x 10 n / 1.5 x 106 = approximately 4.69 It is possible to realize an ideally close two-layer
matching layer type probe. Moreover, the second acoustic matching layer (epoxy) 13 'or the
pressure 14 ? can be obtained by using a kgct single crystal with good processability, instead of
a material with poor processability such as a fused stone, alumina ceramics, glass, etc. as in the
prior art. Because the first acoustic matching layer (AgCl or 12 'can be cut well with the diamond
cutter used for precision cutting of the moving element (PzT) 11', as described above, grating
gloves are generated Satisfying the condition not to let 1. B, @ Cap 15 'between the transducer
elements can be easily formed to about 50 ?m. ???? In addition, it is possible to reduce
crosstalk between each transducer element by 1 to 30 d (three or more, thus realizing an ultracompact probe to be used internally). There is a bamboo tomb that can get a good image once,
and a good image. Furthermore, the best acoustic impedance can be changed by determining the
crystal orientation of the single crystal and injecting an ultrasonic wave perpendicularly to a
specific surface. In addition, Table 1 shows the characteristics of each of the moons and the
structures of the first acoustic matching IN, the first acoustic matching IN, and the $ 2 acoustic
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matching layer, which are modifications of the two-layer matching layer type probe. Table 2 The
CsBr single crystal used here has a cesium chloride type structure and belongs to an equiaxed
crystal system, and the above-mentioned Age I! It is prepared by the same method as single
crystal. However, since the melting point is as high as 640 ░ C., it is better to use a platinum
crucible.
By forming the first acoustic matching layer with CsBr and Qi crystals in this way, the same
effects as described above can be obtained. Next, an example in which the present invention is
applied to a single-matching layer type instead of the two-layer matching layer type of the above
practical example will be described with reference to FIG. FIG. 4 shows an acoustic matching
layer 22 made of PzT pressure city pressure 1 sliding element 21Br single crystal <110>. The
damping layer 23 is basically formed, and silicon is re- sponding to the upper surface of the
acoustic matching layer 22 to make the acoustic matching layer 22 waterproof. Since the K13r
single crystal used here is deliquescent, matching 1-1 of Ehi Tlay probe is preferable, but the
waterproof structure is useful for a single matching layer probe. mh, 3 columns are real! An
example of blood was given, but as a result of observing the tag echo echo and its frequency
spectrum, as shown in Table 3, the conventional single matching layer is compared with a probe
or a two-layer matching layer probe. And sensitivity. It can be seen that the band also has
characteristics of the same level or higher. The present invention is not limited to the
embodiments described above, and can be implemented with various modifications without
departing from the scope of the invention. The present invention relates to the acoustic
impedance of each of the piezoelectric imaging device, the object, the object, and the second
acoustic matching 1- as the material of the two-layer matching first acoustic matching layer or
the single-matching layer sound # matching layer. Correspondingly, four single crystals can be
determined. Table 4 lists the acoustic impedances of typical single crystals. As described above in
Table 4, according to the present invention, an acoustic matching material having a single crystal
is used in # 6 for the ultrasonic probe f- composed of the piezoelectric actuator, the damping
layer, and the acoustic matching layer. By forming a C-type matching layer, it is possible to
provide a super-low-droiling-wave probe having a wide sensitivity and a wide bandwidth and
excellent processability.
[0002]
Brief description of the drawings
[0003]
411fl is a schematic view of a conventional single-matching-layer-type acoustic probe (see UTIiri
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FIG. 2 and FIG. The basic structure and shown in FIG. 2 is an ilF view, FIG. 3 is a cross-sectional
view showing an enlarged part of the main part, and FIG. 4 is a schematic block diagram showing
an embodiment of the pond of the present invention.
? и и и Piezoelectric (? 4b child 2 и и и ? / 4 sound # matching layer 3 и и и damping layer 11. 11 '=
и P' z T / Eit 41i motion child 12. 12 'и и и и north 1 Sound # matching layer 13, 13 'и и и second
acoustic matching layer 14. 14' и и и damping layer 15, 15 'и и и и 16 16 и и и и silicon lens 21-PzT IE
cIIJW motion 22 иии Acoustic matching layer 23 иии Damping layer 24 и и и Silicon lens 25 и и и
Waterproofing member Fig. 1 Fig. 2 Fig. 31 caustic 4 gates 4 cows 1) Spring Darkness 1; display
of the case Japanese Patent Application No. 57-127203 2, и 1 name of ultrasonic probe 3 in
relation to the case of oil exhibitor Patent applicant (037) Olympus Optical Corp. It type company
4 substitute 1 person 5, voluntary f city IE 7, contents of correction (1) Correct the claims of this
application as attached. (2) In the present specification, page 4, line 15, page 5, line 9, line rzJ is
corrected to rZJ. 13) In the same specification 4 # 4th line, line 19, page 6 @ line 9, page 13, line
8, correct the portion of "zoT" as "Zo 'n". (4) In the fifth specification, line 1, line 5, page 3, line 3,
correct the portion of rz = n z O ez ez p J as r Z = n Zo TII Z pl J. (5) the same specification i1:
page 5, line 15, page 6, line 11. Page 6, line 16 "2. "Rzd," part of! :correct. (6) Correct the portion
of "z2" of the specification, page 5, line 18, line 6, line 12, page 6, line 18, page 10, line 16 as
"Z2". . (Force: page 6, line 12, page 12, line 17 to line 18 ? Z, / Z, =% / ?stone wall ;;] 1 ? J
portion rlr / 12 = 7 Z 4 7 shouting; and correct. (8) Correct the portion of rzpJ in the sixth
specification, line 10, 13th specification, line 47, of the same specification to rZpJ. (9) Iz 446, p.
419, rz, / z, = 4.5, and this cough has a portion of / zp / ZOTJ as rZ, 7Z, = 4.5, and this value is s
Correct with / Z p / Z o TJ. (The portion of ?diamond powder J is corrected as? diamond
powder ?in the same specification, page 8, line 13 to line 14). UD 8th line, line 15, page 10, line
11, line 11 table 1, line 13 line 16; 415: Table 2, page 15, bottom line 4, line 18, page 16 @ line
16, line 19 [line PzTJ] is weighed with rPZTJ.
04 Correct the part of the "separator" in the fifth item on page 9 of the same specification as "the
latter." In the same specification, page 12, line 11 "correct the portion of single crystal J as"
single crystal ". (141 ? # 'l @@ page 13 line 5 correct the portion rz + / zzJ as rlt / Z2J. + 151
The same specification, page 13, line 49, r, / zp / zoT "is subjected to r, / Zp / ZoTJ. 2. Claims (1)
A piezoelectric vibrator, a damping layer provided on one plate surface of the pressure vibrator,
and a single crystal acoustic wave provided on the other plate surface of the piezoelectric
vibrator. An ultrasonic probe comprising: a matching layer. (2) The ultrasonic probe according to
claim 1, wherein the acoustic matching layer is formed in a single layer. (3) The acoustic
matching layer is divided into a first sound matching layer and a second acoustic matching layer,
and the first sound # matching layer is formed of a single crystal material and provided on the
piezoelectric vibrator side. The ultrasonic probe according to claim 1. (4) The sound 1 impedance
A of the sound # matching layer sets the pressure (7. =. Me zp-z stone stone relationship between
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the acoustic impedance of the imaging actuator and the acoustic impedance ZOT of the test
medium) The ultrasonic probe (5) according to claim 2, wherein the acoustic impedance zI of the
first acoustic matching layer and the acoustic impedance Z of the second acoustic matching layer.
Is the pressure 4 (the acoustic impedance zp of the rotator and the green impedance ZOT of the
test medium). The ultrasonic probe according to claim 3). (1 '; 1 J': The ultrasonic probe
according to claim 1 characterized in that the size of one block of the acoustic joint layer is the
wavelength of the ultrasonic wave of 0 month / 4. (7) The ultrasonic probe according to any one
of claims 1 to 3, characterized in that a lens for focusing an ultrasonic beam is provided on the
upper surface of the acoustic adjustment layer.
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