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DESCRIPTION JPS57124763

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DESCRIPTION JPS57124763
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of the configuration of the
ultrasonic probe, FIG. 2 shows the relationship between / kp and the polarization processing
electric field E, and FIG. 3 shows / kp (!: Fig. 4 shows the relationship between polarization
temperature, Fig. 4 shows the relationship between w / l of the element of the probe and the
resonant frequency, Fig. 5 a "e shows the pulse response waveform of the probe, FIG. 6 a ? ?-c
shows the composition range and the coupling coefficient in a table. To -T ('C) to-,----
DETAILED DESCRIPTION OF THE INVENTION (1) 74 / 2- (17 (J) 11 ? -f 1 1 1) The present
invention is a piezoelectric ceramic and an ultrasonic probe using the same, particularly an
ultrasonic wave for medical measurement. It relates to an image tentacle. In the conventional
ultrasonic probe of this kite, zircon, titanium, ff-supplied PbZr,-, 'pi, 0.. TPZT) piezoelectric
ceramics are used. The PZ and T iophobic porcelains are characterized by a large
electromechanical coupling coefficient that covers the conversion efficiency of electric and
mechanical quantities, and can be used as a probe for various types of transducers and other
recent electronic scanning ultrasonic tomography devices as well. It is used. There are currently
two types of this electronic scanning type: single-element linear scanning and electronic sector
fixed corrosion, but as shown in FIG. 1, each of the probes is a small strip-shaped power
transducer made of piezoelectric ceramic in a one-dimensional array The structure is arranged in
a large number. Note that, in the first factor, 11 is a piezoelectric ceramic that is polarized
perpendicularly to the plate surface, 12 is an electrode, 13 is a common electrode, 14 beams are
1-wires, and 15 is a backing material. In such a probe, since the thickness longitudinal vibration
of each of the transducers is used in ft1, the fundamental frequency is basically determined by
the thickness t of the transducer. However, piezoelectric ceramics such as general KPZT series
have not only thickness longitudinal vibration but also width vibration K (2) 147 in the lateral
direction; Is actually in coupled vibration mode. Therefore, if the ratio W / l of the width W to the
thickness t of the vibrator is increased, the pulse response characteristics of the silicon probe
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whose influence in the lateral vibration is large deteriorate. In this sense, the llw K upper limit of
? w / t is practically found (w / l (0, 8) in the PZT system). After development of fc projection for
organ diagnosis using ultrasonic waves of about 10,000 and 2 to 3 MH2, recently, it is required
to further improve the resolution of these devices by 1 to 1 . Therefore, the high frequency of the
ultrasound probe is! It is a mourning task. In order to increase the frequency of the probe, it is
necessary to reduce the thickness t of each transducer. However, as described above, since there
is an upper limit to w / t, the width of the transducer is inevitably accompanied by the increase in
frequency. W gold 1-. I have to narrow down. However, there is a limit to the cutting process to
make arrayed probes. In the array type probe using PZTi porcelain, it is difficult to increase the
frequency. Therefore, even if w / t (1B + 1 is large to a certain extent, thickness, 1 ░ (3) 481-?
blind person 1) a material in which a mode close to longitudinal vibration is excited, ie, an
electromechanical coupling coefficient related to lateral width vibration It is becoming essential
to use materials that have a small size.
Recently, as a material that meets such requirements, PbT10. The usefulness of PbTiO3 series
ceramics has been reported on page 117 of the 54th Annual Meeting of the Electronic
Communication Society of Japan in 1984. But normal pbTto. The ratio k, / k of the
electromechanical coupling coefficient in the lateral direction and the electromechanical coupling
coefficient in the thickness direction #i ? is about 6 to 10, and both are still saved in both types
of ceramics. The vibrational coupling of the probe is strong, for example, in the area of w7t-1
where the coupling is strongest, the pulse response waveform of the probe becomes impractical.
Also, even in the range of w / t 1.5 to 3, the pulse response wave 1 ░ form is not sufficiently
satisfactory. Therefore, an object of the present invention is to provide an ultrasonic probe which
can withstand practical use not only in the region of W / l = 1.5 to 3 but also in the region of W /
l and l. This invention. The piezoelectric ceramic used in ultrasonic probes is PbO, which is
compositionally. ????????? 447 to 46.3 mol%, T101 t5a, 9 to 51.7 mol%, 1.8 to 26
mol% of Sm30s, and 5 to 1.0 mol% of MnO ?, and 45. 10% of PbO; 3 to 47.4 mol%, 410 to 51.0
mol% of T101, 1.8 to 27 mol% of S "gost", и 3 to 1.6 mol # of I "mow, ? 5 for MnO, It contains ~
1.0 mol%. These are some of the senses already disclosed in JP-A-54-142 597 K as a
piezoelectric ceramic composition, but the present invention uses the composition in the above
composition range in a temperature range of 130-160 C, ... Electromechanical coupling
coefficient k by applying an electric field of 80 KV / cIR and performing polarization treatment. Is
based on the discovery that a very small piezoelectric ceramic can be obtained. When an
ultrasonic probe is formed using these porcelains, the electric 1 ░ mechanical coupling
coefficient is extremely small, so that the pulse response waveform is the same as that of the
conventional PbTi 0. A more refined product is obtained as compared to the one using a ceramic.
Hereinafter, the present invention will be described in detail with reference to the embodiment t? 2. (5) To 50 corridor-:: 4. (1) The raw material powders shown in Table 1 shown in FIG. 6 (a)
to 5 g 6 (C) and having the fc composition ratio are wet mixed for about 1 hour using a bot mill,
dried and then 2 o'clock j-temporarily sintered at 850C. I did. The pre-sintered body was crushed
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using a grinding machine and mixed again using a pot mill. After drying, it was pressed at a
pressure of 350- и h / c and sintered for 5 hours at 1260C.
The pellet size after sintering is 16? О 2iW. After the pellet was ground with about ? 8111
111 J 41 L 1, Cr and Au were observed on both (3) as # and the copper lead wire was baked with
silver paste. After subjecting these 1 <1 sample to treatment with silicon [in mountains 150 c, 60
KV / c IR for a treatment of 1 million parts, electromechanical coupling coefficient], the results
are simultaneously shown in Table 1 Show. In the above Nut, Examples 1 to 7 are I "Hot Ost" l
Knee. Included is the result for the ai #. From these results, 44.7 to 46.3 mol% of PbO, T shaking
O snow. Within the composition range of 50.9 to 51.7 mol%, Srn, Q, 1.8 to R6 mol%, and
M??Ox of 0.5 to 1.0 mol%; In the case of Example 3, the ratio of 211 / kg 211 (6) 151 ? 5N-J и
? ? 1 becomes more than 10 in the ratio of 20 t ? in the case of Example 3. Over. In Examples
1 and 7, when the weight of each of Sm and O is less than 1.8 mol%, the weight is more than 26
mol%, but in each case, the weight is 10 or less. . Next, Examples 8 to 22 contain I "gos, but
depending on the composition, it can be seen that the combination of srn, o, and I" gos makes / g
etc. larger. Example 8 still has sm, o, in a case where the amount is less than 1.8 mol%, иии, lO less
than in Example 9, Examples 8 to 14 have 8 tr + t O1 of 1.8 to 2 иии. In the case of 17%, I ? ? tOs
is further added with ?3 to 1.6 mol%, but in all cases, k and / k are much more powerful than
when I??ton is not added. . In fact, Examples 15 and 16 show cases where the amount of I ?
? goss is less than ?3 mol%, more than 1.6 mol%, but both add I ? ? tos and no effect is
observed. Examples 17, 18 and 20 show the effect of adding IntOn. Example 19 is Sm O Os ?,.
When 1 (? 52 ? [1 group knee) 1 amount exceeds 27 mol%, k, / is divided by 10 t?. In
Example 21, the amount of PbO 0 is less than 45.3% by mole, and the ratio of Tie, ? is more
than 51.0% by mole, k, / k. Is smaller than ten. Further, Example 22 is the case where the charge
of 1PbO exceeds 47.4 mol% and the amount of T101 O is less than 47.9 mol%, but the effect of
adding 1 '' 10 m is not recognized. As described above, 45.3 to 47.4 mol% of PbO, 47.9 to 51.0
mol% to TtQ, 1.8 to 27 mol% of am, O, and I ? ? 103 of 0.3 to In the composition range of 1.6
mol% and Mn01'lI: ?5 to 1.0 mol%, 1 [of Kkt / is further increased by adding IntOa to the above
composition.
In addition, 0.5 to 1.0 mol% was appropriate for M??OtOitK in common to 15 porcelains
having the two composition ranges described above. If the Mno concentration is less than 0,5
mol%, the sample may be broken by polarization treatment with high electric field, which is
necessary to reduce the electric field, and if it exceeds 1,0 mol% Due to the decrease in
resistance, 0 (al'75: 3 и и и; ",", ","-1 "Polarization processing with -1 electric field became difficult.
Next, polarization processing conditions and electromechanical coupling coefficient ratio k. Show
the relationship between /. With respect to the compositions of Examples 3.6.11 and 18, the
results are shown in FIG. 2 when the polarization temperature is constant at 150 C and the
polarization electric field is changed. In the range of 20 to 40 KV / CIn, the polarization
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treatment electric field is small, but when it exceeds 40 KV / crn, the Hkt / kpH rapidly increases
and exceeds 10 O in most compositions above 60 KV / ?. When the polarization temperature
was further raised, k and / k increased to 1 ии 80 KV / ?, but when the electric field was applied
above that, the samples of most compositions were broken. As a matter of fact, the polarization
treatment needs to be performed at an electric field in the range of 60 to 80 KV / w. With
respect to the compositions of Examples 3, 6.11 and 18, the change in / when the polarization
temperature is changed with the polarization electric field constant at 60 Kv / m. As is clear from
FIG. 3 showing the conversion, when the polarization temperature exceeds 1300, k and / k
become larger than 10 for most compositions. However, when the temperature 73 ((? 54 ? p 2
и 1 1 exceeds 11 1 U, the resistance decreases), and it becomes difficult to apply a ^ -field of 60 /
cln or more to 60. Thus, the polarization temperature must be set to a value of 130 to 160C.
Next, using these piezoelectric ceramics, a large number of strip shaped vibrators having
different 1 ratio w7t of width W and thickness t (constant thickness t) are created, and vibration
mode in the thickness direction (longitudinal mode) and width direction low The relationship
between the co-frequency and the w / t in the dynamic mode (horizontal mode) was measured.
One example is shown in FIG. The composition of Mt. Kozu is in the case of Example 3 (minute Ill
treatment temperature 150 C, polarization treated electric field 60 KV / bar), the resonance
frequency of the longitudinal mode (curvature @ 417 is w / t at 1 @ d almost depends on
Without this, the coupling between the longitudinal mode 41 and the transverse mode 42
changes only slightly near the strongest w / t-1. Furthermore, the influence of the coupling is less
in the w / 1-40 region where the still mode 43 of the 1.1 horizontal mode and the longitudinal
mode 41 are coupled.
This indicates that the longitudinal mode is overwhelmingly dominant regardless of the value of
w / l, because it is extremely small. That is, such a piezoelectric ceramic is used for 11 (10) 55
islands. Right! A movement similar to a pure thick vertical ice movement is excited regardless of
the number of Go * 1'-1 short * shaped transducers FiW / t. Actually, for this piezoelectric
ceramic, an ultrasonic probe as shown in FIG. 1 is prepared, and an example of measuring its
pulse response waveform is shown in the conventional PbTi01 series ceramics- ? (k, / k, ~6). The
results are shown in FIG. 5 (a) to 5 (d) show that an ultrasonic probe is applied with a pulse
voltage by a pulse generator using a thyristor, an ultrasonic wave is generated in water, and an
echo waveform from a reflector is displayed on an oscilloscope. It is what I observed in 11. The
fifth p (a) + (b) + (cL (d) and (e) have W / l = 0.8, 1.0.1.5, 10, respectively. It is a result about the
probe of & 0. As is clear from FIG. 5, the pulse response waveform of the probe of the present
invention has a shorter pulse length as compared with the conventional one, and the resolution
can be further improved. In particular, in the probe with w / 1 = Lo (b) In the probe using the
conventional PbTiOs-based porcelain, the waveform is not acceptable for practical use, but the
probe of the present invention can be used The state Ki has been improved. These results are the
pressure used in the present invention. . (11) Ba to 75, -2; however, because of the extremely
small 'G <kt / kp' of the electric arc instrument, the thin frame thickness longitudinal vibration
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TIJJK close to each transducer element of the probe Is based on excitation n. Thus, although the
ultrasonic probe of the present invention exhibits excellent characteristics in the range of W / l =
0.8 to aO, it can be used even in the conventional PZT-based porcelain at W / t <0.8 The
characteristics using the piezoelectric ceramic of the present invention are not useful, or at W /
l> 3.0, the width of each transducer element is too narrow p too much and the image quality of
the ultrasonic image is degraded and practically meaningless It becomes. Thus, 44.7 to 46.3
mol% of PbO, 50.9 to 51.7 mol / '% for T blood 0 *, 1.8 to 16 mol% for Sm, Q, 0 for MnQ, And
porcelain containing Pb in 0.5 to 1.0-1/1 /%, PbO '1-45.3 to 47.4 mol%, Ttot ? a 7.9-s1. o mol%,
Snl, 0. In porcelain containing 1.8 to 17 mol%, In, o, 0.3 to 1.6%, MnOH 0.5 to 1.0 mol%. Array
type ultrasound probe using a nine pressure porcelain with polarization applied by applying an
electric field of 60 to 80 KV / ? in the temperature range of ~ 160 c can obtain W / l = 0.8 to 2,
1 (121 It is obvious that the characteristic which is extremely excellent is shouldered in the
range of '75 1 1 ? 77 h-?, '1 s 1-1' +13.0.
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