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DESCRIPTION JPS6258800

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DESCRIPTION JPS6258800
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe used for medical or underwater search and the like, and more particularly to the
improvement of the acoustic matching layer of a probe using a piezoelectric ceramic as a
vibrator. [Prior Art] An ultrasonic probe using a piezoelectric ceramic as a vibrator has already
been put to practical use. When this ultrasound probe is used for medical or underwater search,
piezoelectric as a vibrator! The key is to minimize the loss of ultrasound by matching the acoustic
impedance between the ceramic and the outside. Assuming that the acoustic impedance of the
piezoelectric ceramic is zp and the acoustic impedance of the human body or water is Zo, the
acoustic impedance ZM of the acoustic matching layer can be expressed as zw = F stone = 1−.
Usually, Zp is 33 × 10 @ Aym ′ ′ ′ ′ ′ ′ ′ 5ee− ′. Zoは
1.5X10@@rn−8sec−’なので、ZMは7X10’Aym−”seeとなる。
However, there is no material having an acoustic impedance close to the ZM. Therefore, it has
been considered to obtain the required consistency by combining a plurality of acoustic matching
layers. For example, the first layer of G Of 1 (IE "l'rons 3omics & vl rasomics 5U-26 [11] 1977 P
385]: ZM 1 = 4W: 15 X 10 'hm-" 5ee- "second layer: Z M 2 = 4u It is shown that: 3.2 X 10 "Ay m25 a knee". ZMI is close to the acoustic impedance of quartz glass and some crystallized glass <,
ZM! Is the same as the acoustic impedance of engineering plastic. In the past, many cases used
an acoustic matching layer combining these materials. [Problems to be Solved by the Invention]
When a crystallized glass is used as an acoustic matching layer, the thermal expansion coefficient
is approximately 9 × 10− ′, and the thermal expansion coefficient of the piezoelectric ceramic
is 4 × 1 (r ′ greatly different from r ′. Become. Therefore, in the ultrasonic probe formed
using the above-mentioned material, thermal distortion will be generated when heat treatment is
performed at the time of processing or at the time of disinfection. As a result, there has been a
problem that the first acoustic matching layer joined to the piezoelectric ceramic peels off from
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the piezoelectric ceramic. In particular, in the arrayed probe, since the ultrasonic transmission /
reception cross-sectional area of each element is small, the bonding area is also small. For this
reason, the adhesive strength with the piezoelectric ceramic is weak, and the peeling
phenomenon is likely to occur.
Therefore, the present invention can prevent the peeling phenomenon due to the thermal strain
between the piezoelectric ceramic which is the vibrator forming member and the acoustic
matching layer without impairing the acoustic matching property and the machinability, and is
easy and inexpensive to manufacture. It is an object of the present invention to provide an
ultrasonic probe that can be manufactured in [Means for Solving the Problems] The present
invention is characterized in that the following means are taken to solve the problems and
achieve the object. That is, the acoustic matching layer has a thermal expansion coefficient
equivalent to that of the piezoelectric ceramic, and has an acoustic impedance approximately
equal to 4n 57 when the acoustic impedance of the piezoelectric ceramic is ZP and the acoustic
impedance Zo of the human body, and mechanical machinability Use crystallized glass superior
to [Operation] By taking such means, the thermal expansion coefficients 1j 4 of the piezoelectric
ceramic constituting the vibrator and the crystallized glass constituting the acoustic matching
layer become similar, so that heat is externally applied. Even if there is no thermal strain at the
junction of the two. Also, the acoustic impedance of the acoustic matching layer has a value at
which a sufficient impedance matching can be obtained. Furthermore, it becomes easy to process
and can easily make an array-like probe etc. FIG. 1 is a perspective view showing an embodiment
of the present invention. 1, an ultrasonic transducer made of piezoelectric ceramic on a damper
1; First acoustic matching layer 3a, second acoustic matching, @ 3 b. The acoustic lens 4 is
sequentially laminated. FIG. 2 is a cross-sectional view showing a part of FIG. 1 by cutting it. As
shown in FIG. 2, the ultrasonic transducers 2 made of piezoelectric ceramic are divided into a
large number and arranged in an array so as to constitute independent elements. The first and
second acoustic matching layers 3d and 3b are similarly divided and arranged in an array. The
first acoustic matching layer 3a is a crystallized glass having a thermal expansion coefficient
equivalent to that of the piezoelectric ceramic 2 constituting the ultrasonic transducer 2 and a
required acoustic impedance, and having excellent machinability. It is formed. The said
crystallized glass is produced as follows. The raw materials are mixed with the patch composition
shown in Table 1 and melted at 1300-1400 ° C to obtain a glass. Table 1 Next, the glass sample
is heat-treated at 600 to 1000 ° C. to obtain a crystallized glass. In precipitating crystals by the
above heat treatment, it is known as mica (Na -MI 3 (S 1aAJOto) Fs), which exhibits good
machinability, and a low thermal expansion material, by selectively controlling the composition
and the crystallization schedule. Ss-s, s-, y, Umen (LiLi0 · AI!
'02 · 4SiOz) is simultaneously deposited at a predetermined ratio. By doing this, it is possible to
form a lath that has a thermal expansion coefficient close to that of the piezoelectric ceramic and
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has the required acoustic impedance to make it machinable. Table 2 is a table showing various
physical properties of the crystallized glass obtained as described above in comparison with the
conventional product. As apparent from Table 2 and Table 2, the product of the present example
is provided with the required physical properties at the same time. As described above, according
to the present embodiment, the crystal glass obtained by appropriately selecting the composition
and the crystallization conditions is adapted to the conditions required as the acoustic matching
layer. Therefore, in an array-like probe using the above-mentioned crystallized glass as an
acoustic matching layer, of course the required function can be exhibited as an ultrasonic probe,
and the thermal expansion coefficient is close to that of the piezoelectric ceramic as the vibrator
2 Even when heat is applied during heat treatment or disinfection, thermal distortion does not
occur. As a result, it is possible to prevent the occurrence of the exfoliation phenomenon as has
conventionally been a problem. Further, since the crystallized glass does not contain any harmful
toxicity to the living body, it is suitable as a medical ultrasonic probe used for the human body
and the like. Furthermore, since inexpensive materials can be easily manufactured by a simple
manufacturing method, there is also an advantage that production costs can be reduced.
According to the present invention, since the crystallized glass having a thermal expansion
coefficient substantially equal to that of the piezoelectric ceramic which is the vibrator forming
member is used for the acoustic matching layer, the acoustic matching property and the cutting
processability are impaired. As a result, it is possible to prevent the peeling phenomenon due to
the thermal strain between the piezoelectric ceramic and the acoustic matching layer, and to
provide an ultrasonic probe which is easy to manufacture and can be manufactured
inexpensively.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a perspective view showing the appearance of an embodiment of the present invention,
and FIG. 2 is a cross-sectional view showing the main part of FIG.
1: Dan / 4'-12: Ultrasonic transducer (piezoelectric ceramic), 3813b: First and second acoustic
matching layers, 4: Acoustic lens. Applicant Agent Patent Attorney Tsuboi 淳 fI! 1 Figure 2
Procedure correction letter ++ iun <Po ♀, 23 ° General Secretary of the Patent Office 道 即 殿 1,
display of the case Japanese Patent Application No. 60-197135 2, title of the invention ultrasonic
probe 3, correction Patent applicant name (037) Olympus Optical Co., Ltd. 4, correction of agent
procedure Showa year 61A2 · · · also Secretary of the Patent Office Black 1) Akio 1 display of the
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case Japanese Patent Application No. 60- 197135 No.2 name of the invention Ultrasonic probe 3
Relationship with the case of correction Patent applicant (037) OLYMPUS OPTICAL CO., LTD. 4
Agent 3-7 7 UBE Bill 7, Content of correction (1) Correct the claims as described in the attached
sheet. (2) “Normal zp is shown in the specification on the second page, line 9 to line 20. "As
follows. Since “normally zp is 33 × 106 kg1ll−2 sec− ′” and Zo is 1.5 × 10 6 kgm−2
sec− ′, ZM is 7 × 10 6 kgm-2 sec. However, there is no preferred acoustic material having an
acoustic impedance close to the ZM. Therefore, it has been considered to obtain the required
consistency by combining a plurality of acoustic matching layers. For example, in Golf (IEEE
Trans 5onics & Ultrasonics 5U-26 [11 co 1977 P, 385), first layer: Z ML-r "L 5 x 106 kg m-" S
(3C "second layer: ZM 2-6 It is shown that = 3, 2 x 106 kg m-2 sec-'. "Correct" as "Zo H7". (4)
“Acoustic matching layers 3d and 3bJ in the fifth line of page 17 of the same document are
corrected as“ acoustic matching layers 3a and 3bJ ”. (5) Correct “Table 2” on page 7, line
11 to the last line of the book as follows. Table 2 (6) Correct “Crystalline glass” in the same
row, page 8, line 4 as crystallized glass. 2. Claim Zp acoustic impedance of the piezoelectric
ceramic having a thermal expansion coefficient equivalent to that of the piezoelectric ceramic.
When the acoustic impedance of the human body is Zo, shifoko-777
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