JPS6378700A - Composite piezoelectric ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic probe with a high sensitivity and a wide band by employing a porous ceramic piezoelectric body as a piezoelectric body. CONSTITUTION:The hole ratio of the porous ceramic piezoelectric body can be varied by freely changing the mixture ratio of ceramic fine powder and a binder, or the foaming condition of polyurethane and calcination conditions. The hole ratio can be selected within a range of 0.10-0.75, preferably 0.30-0.65. It is acceptable that the porous ceramic piezoelectric body contains holes including high molecular compounds, or gas holes. One of manufacture is introduced. The PZT-based porous ceramic piezoelectric body with the hole ratio of 65% and a dielectric constant of 250 is provided with silver electrodes 3 and 3'. After the body is polarized, it is cut into parts in 8 mm X 8 mm. The porous ceramic piezoelectric body 1 and a tungsten plate about 500 mum in thickness are bonded with adhesives 9 and 9'. A packing member 10 made of ferrite rubber is jointed with a similar adhesive. Thus the direction in which an ultrasonic wave is transmitted is the direction of an arrow (a).

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a composite piezoelectric ultrasonic probe used in an ultrasonic diagnostic device or the like.

(Prior Art) Ultrasonic probes using a so-called composite piezoelectric material, which is a combination of a ceramic piezoelectric material and a polymeric piezoelectric material and has the characteristics of both, have been actively studied.

A feature of composite piezoelectric materials is that in addition to being able to select a composite model according to the application, it is also possible to receive ultrasonic waves and generate electrical output without reducing the piezoelectric strain constant (d constant), which is directly involved in the generation of ultrasonic waves. The point is that the directly related voltage output constant (g constant) can be increased. Furthermore, this piezoelectric material has a lower acoustic impedance than a ceramic piezoelectric material, and has a better acoustic matching with the living body (see Figure), which improves the propagation of ultrasonic waves.

JP-A-58-2 as an ultrasonic probe using composite piezoelectric material
There is one described in Publication No. 1883. This ultrasonic probe uses a 1-3 type composite piezoelectric material layer, and after bonding the ceramic piezoelectric material onto a substrate with a flat surface, a number of grooves are formed to completely separate the piezoelectric material. The grooves are then filled with organic matter and solidified. When this ultrasonic probe uses a seven-piece piezoelectric material, it has a structure in which ceramic piezoelectric rods and filling organic matter are arranged alternately, which causes unnecessary resonance due to the arrangement period, resulting in a decrease in sensitivity. However, the ringing of the echo waveform becomes longer.

(Points to be solved by the invention) As mentioned above, the composite piezoelectric ultrasonic probe has poor sensitivity.
There was a problem in that the ringing of the echo waveform was long.

The present invention has been made in view of these problems.
The purpose is to provide a composite piezoelectric ultrasonic probe with high sensitivity and wide band.

[Structure of the invention]

(Means and effects for solving the problems) The present invention provides an ultrasonic probe equipped with a vibrator having a piezoelectric body and an electrode.
This is a composite piezoelectric ultrasonic probe characterized by using a porous ceramic piezoelectric material as a piezoelectric material.

The porous ceramic piezoelectric body used in the present invention may be any ceramic piezoelectric body having holes, and is not particularly limited.

The porosity of the porous ceramic piezoelectric material used in the present invention can be arbitrarily changed depending on the mixing ratio of the fine ceramic powder and the binder, the foaming state of polyurethane, the firing conditions, etc. Porosity 0.10~0
．． 75 Preferably, if it is less than 0.30, the characteristics of the composite piezoelectric material cannot be fully utilized, and it exhibits properties (dielectric constant, d constant, g constant, Young's modulus, etc.) similar to conventional ceramic piezoelectric materials. , and in the case of a porosity exceeding 0.65,
This is because the porous ceramic piezoelectric material exhibits properties such as being easily damaged and having an extremely low dielectric constant.

Further, in the porous ceramic piezoelectric body of the present invention, the pores may contain a polymer compound or may be pores.

Further, the piezoelectric ceramic used in the present invention may be any piezoelectric ceramic that is generally used as a piezoelectric material, such as pb(Zr-Ti)03 piezoelectric ceramic represented by PZT. ,
Examples include BaTiQ3, PbTiO3, and the like.

Further, the composite piezoelectric ultrasonic probe of the present invention may be provided with the plate materials shown below.

As a plate material, the acoustic impedance of the porous ceramic piezoelectric material (ZAO) and the acoustic impedance of the plate material (ZA
1) may be joined. In this case, the porous ceramic piezoelectric material and the plate material apparently operate as an integrated vibrator.

Therefore, if only a porous ceramic piezoelectric material (thickness t) is used as a diaphragm, the relationship will be λ-2t when the wavelength λ at the time of its reference vibration is λ-2t, but if such a plate material is provided, the relationship will be λ-2( to+t1) (to' thickness of the porous ceramic piezoelectric material, thickness of the tlI plate material). In this case, there is a thickness for the electrodes, but it is generally thin, less than 10-odd micrometers, so it can be ignored. Therefore, when driving with the same number of laps,
That is, in order to obtain the same wavelength λ, it is sufficient to satisfy the relationship: to+tl-t, so the thickness to of the porous ceramic compact becomes to-t-tl. In order to obtain the same frequency in this way, the thickness of the porous ceramic piezoelectric material to which the voltage is applied only needs to be (it x Vt (<1) times).

Since capacitance is inversely proportional to the thickness of the porous ceramic piezoelectric material to which a voltage is applied, the capacitance is t /
(t-t IX > 1) times the force, similarly the electrical human power impedance is approximately (t-t
) becomes twice as small.

In this way, electrical input impedance can be reduced regardless of material properties.

In addition, it is possible to reduce the electrical input impedance to a range that could not be reached by material conversion alone, so the output impedance of the pulsar can be reduced, improving the S/N ratio, reducing power consumption, and reducing impedance. Therefore, many effects can be obtained, such as ease of alignment and reduction in the amount of heat generated by the ultrasonic probe.

In order to operate two plates as one vibrator in a pseudo manner, it is preferable to have ZAO (acoustic impedance of porous ceramic piezoelectric material) minus ZAI (acoustic impedance of plate materials to be joined).

When ZAI becomes smaller than ZAO, the above-mentioned to tent
If the sensitivity is large at a frequency where one wavelength exists in lO, that is, twice the desired frequency, the sensitivity in the desired frequency range will be reduced. For example, if the density is changed while keeping the sound speed constant, ZAI is 0.7
When ZA0 or less, sensitivity begins to increase at frequencies twice the desired frequency as described above, and when the density is kept constant and the sound speed is varied, ZAI to 0.
When the temperature drops below about 8ZA0, the same phenomenon as described above begins to occur. Follow, ZA1≧0.7ZAO,% ZAl, m
o, 6 with 8ZAO is preferable.

Furthermore, as ZAl increases, ringing tends to occur, and so-called tailing becomes longer. For example, if you change the ZAI by changing the density while keeping the sound speed constant in winter cropping with a constant board thickness, the ZAI will be 2. When ZAO is exceeded, the time required for the amplitude to become 1 / I O is approximately 30% longer, and when the density is kept constant and the sound speed is varied, when ZAI exceeds 2.2ZAO, the time required for the amplitude to become 1 / I O is approximately 30% longer. It becomes somewhat longer. Therefore ZA! A range of ≦2.2ZA0 is preferable.

As described above, the case of ZA 1 -ZA0 is preferable, but if it is in the range of 0.7ZA0≦ZAI≦2.2ZA0, it exhibits substantially the same behavior as ZA 1 -ZA O. Special KO, 7ZAo≦ZA1≦1.4ZAo If the cD range is torn, an integral vibration is generated like ZA 1 -ZA0, and it is effective.

In addition, although the thickness of the plate material is 11), although it is operated as a pseudo-oscillator, what actually transmits and receives ultrasonic waves is a porous ceramic piezoelectric material with electrodes. , tl so that the strain in the thickness direction of this porous ceramic piezoelectric material is maximum at the time of reference frequency resonance.
Preferably it is mto.

In the present invention, the input impedance can be reduced by providing a reflector having an acoustic impedance ten times or more that of the porous ceramic piezoelectric material.

The acoustic impedance of a porous ceramic piezoelectric material is generally 1c5×15×10 Kg/dS. 5-10
Consider a case in which a porous ceramic piezoelectric material having an acoustic impedance of 10 x lo h/s/S and a reflecting plate having an acoustic impedance approximately lθ times that of the porous piezoelectric material are bonded with an adhesive or the like. The material constituting the reflecting plate may be metal such as steel or tungsten, or a mixture of tungsten powder and epoxy resin.

Resonance occurs when a pulse voltage is applied to the electrodes at both ends of this ultrasonic contactor. Resonance at the lowest order, the so-called reference frequency, is usually used. Figure 2 shows the concept. The joint surface between the porous ceramic piezoelectric body (1) and the reflection plate 0 becomes a node of vibration.

This is because the acoustic impedance of the reflector ■ is sufficiently larger than that of the porous semi-mixed piezoelectric material (1), but on the other hand,
Since we are considering the reference frequency, the other end becomes the antinode of vibration (Figure 2 (b)). Figure 2 shows a porous semi-mixed piezoelectric material (
The relationship between the large thickness and the wavelength λ in 1) is t-λ/4. By the way, in order to obtain this wavelength λ using only a porous ceramic piezoelectric material, steps 7, 7, and 7 shown in FIG. Porous ″″Mi′
The thickness of the piezoelectric body is 2゜, and the midpoint of the direction is the node of vibration. The standard vibration of ordinary ceramic piezoelectric material is this second
It is a diagram.

Comparing Figures 2 and 3, we can see that to obtain the same frequency, the pressure of the machine shown in Figure 2 is 1! This means that the thickness of the element may be equal to A in the case of FIG. Therefore, considering the input impedance, it becomes A, which means that the impedance has been reduced.

The porous ceramic piezoelectric body used in the present invention is made by kneading PZT ceramics, which has been pulverized in advance, with a binder such as acrylic resin or polyvinyl alcohol.
Polyurethane can be obtained by molding it into a block or sheet shape and then firing it, or by mixing PZT ceramic fine powder with a polyurethane stock solution in advance, foaming the polyurethane to obtain a desired shape, and then firing it. It can be easily obtained by polarizing porous ceramics obtained by a method such as vaporizing components.

Although the shape (size) of PZT ceramic fine powder for obtaining a porous ceramic piezoelectric body is not particularly limited, a powder diameter of 20 μm to 150 μm is widely used. The binder is also not particularly limited (it can be selected from among those that can disperse the PZT ceramic fine powder well and can be vaporized and removed during firing).

An ultrasonic probe using a porous ceramic piezoelectric material can be manufactured in the same manner as a conventional semi-mix ultrasonic probe or a polymer ultrasonic probe.

(5A example) Next, embodiments of the present invention will be described in detail.

1) Example 1 PZT ceramic powder was mixed with water-soluble acrylic resin and PV
A dispersion liquid using A as a binder was prepared (binder ratio 0.04), and this was formed into a sheet shape and fired to obtain a porous 2-mix piezoelectric material with a porosity of 43% and a relative permittivity of 520. Next, an epoxy resin mixed with silver powder (manufactured by Dortite, trade name D-753) was applied as an electrode to both surfaces of this porous ceramic piezoelectric material, hardened, and then polarized. The shape was 8 x 8 m, and the thickness was adjusted so that the frequency of the ultrasonic probe was 5 MHz.

A polyimide film (manufactured by Toshi Co., Ltd., trade name: Kapton) was attached to the sound operation side to form a sound #matching layer.

Next, as a comparative example, a piezoelectric material as shown in FIG.
The epoxy resin (7) (trade name Ecobond 24) was injected into the grooves by cutting them into mesh-like pieces with a width of 200 μm.
Filled. The electrodes (not shown) of this composite piezoelectric material are made of epoxy resin mixed with silver powder (manufactured by Dotite, trade name: D-
753) was applied to both sides and cured. Especially piezoelectric material is 8
The main acoustic characteristics of the X8M electric body are shown.

For each of the various piezoelectric bodies, a sound #matching layer a3ni was provided as necessary on the working side that would become a λ/2 type ultrasonic probe.

Regarding the above ultrasonic probe, performance evaluation of the ultrasonic probe was carried out using Sei Arotechku Co., Ltd. product name UTA-3. The evaluation was performed by analyzing the reflected waves from an acrylic block placed at 70° in the water, and determining the operating center frequency (fo
), sensitivity (d13...However, the 7 tenator level when adjusted so that the pulse echo wave displayed on the oscilloscope is 100 mV is displayed in dB, and the band (11 for fo)
The frequency range of 0 dB was defined as Δf/fo).

The evaluation results are shown in Table 2.

Table 1: Main acoustic properties of various piezoelectric materials Table 2: Evaluation of ultrasonic probes using various piezoelectric materials I got a child.

l1) Example 2 (example in which a reflector with an acoustic impedance of 10 times or more is provided) P with a porosity of 659 g and a relative permittivity (ε black/”o) of 250
Silver electrode (3) on ZT-based porous ceramic piezoelectric material. (
3') and after polarization treatment, 8++aX8m
It was cut into The thickness t of the present porous ceramic piezoelectric body (1) was measured and found to be 216 μm. This porous ceramic piezoelectric body (1) and a tungsten plate having a thickness of approximately 500 μm were bonded together using an adhesive (trade name Kobo Botech 301, manufactured by Muromachi Kagaku Kogyo Gt!m). Furthermore, a backing material a0 made of ferrite rubber was bonded using the same adhesive. Therefore, the transmission direction of the ultrasonic wave is the direction of arrow a. (
(See Figure 5) The electrodes (31,
i! extracted from (3') Both ends of the electrode lead.

b′ with an impedance analyzer (product name 4 manufactured by YHP)
92A) and measured the input impedance under water load. The results are shown in FIG. 6 (curve a in the figure).

The ultrasonic probe of this example was used to measure the echo waveform and its frequency spectrum by the pulse echo method.
The echoes of the acrylic blocks placed in the 7th section of the water were measured. When the center frequency was determined from the frequency spectrum of the echo wave, 2.28 MHz was obtained. The input impedance of the ultrasonic probe at this frequency was 88Ω as shown in FIG. 6(a).

Next, for comparison, a λ/2 expansion probe with a similar center frequency was prototyped. The structure is such that a porous ceramic piezoelectric body and ferrite rubber are bonded together using the adhesive described above.

The input impedance of this ultrasonic probe under water load is shown in FIG. 6(b).

2, the impedance at 28 MHz is 173
In the case of this example, it was approximately A. It goes without saying that similar results can be obtained even if a sound matching layer is provided on the ultrasonic wave transmitting/receiving surface.

In this way, we were able to achieve a lower impedance that could not be achieved with the same frequency, resulting in improvements in the S/N ratio, ease of impedance matching, and reduction in the amount of heat generated by the ultrasonic probe. can.

111) Example 3 (an example in which a plate material with substantially the same acoustic impedance was provided) PZT with a porosity of 38% and a relative dielectric constant (ε5/ε0) of 471
Silver electrode (3) on porous ceramic piezoelectric body.

(3) The thickness of the porous ceramic piezoelectric body (1), which was cut into 8×8N after being installed and polarized, is t.
When measured, it was 216 μm. A plate material (2) made of the same material and the same thickness as this porous ceramic piezoelectric body (1)
) was bonded to one surface of the porous ceramic piezoelectric body (1) via an adhesive layer (9) (trade name Kobotech 301, Muromachi Chemical Industry Co., Ltd.). In addition, one pole (31, (3) '
Both ends of the electrode lead taken out were connected to an impedance analyzer (YHPfi product name 4) 92A), and the input impedance was measured under water load. The results are shown in Figure 7 (song yma in the figure).

The resonant frequency was 2.45 MHz. In addition, as a comparative example, a thickness (385 μm) was used so that the resonance frequency reached 2.45 MHz without using the plate material (4) in this example.
Similar measurements were carried out using an ultrasonic probe set to (curve b in Fig. 7).

As is clear from the seventh factor, lower impedance is achieved in this example than in the comparative example at the same frequency.
At 2.65 MHz, the resistance of this example was 37Ω, and that of the comparative example was 690, which was approximately %. It goes without saying that similar results can be obtained even if a sound qj matching layer is provided on the ultrasonic wave transmitting/receiving surface.

In this way, we were able to achieve a low impedance that was previously unattainable at the same frequency, improving the S/N ratio and
Effects such as ease of impedance matching and reduction in the amount of heat generated by the ultrasonic probe can be obtained.

IV) Example 4 Using the same method as in Example 1, the porosity was 39 cm, the electromechanical coupling coefficient kt was 49%, and the relative permittivity was 4. /ε0547, a thickness of 300 μm, and a shape of 20 w x 15 m. A porous ceramic piezoelectric body was manufactured. Using this porous ceramic piezoelectric material, ultrasonic probes as shown in the schematic diagrams of FIGS. 8 to 13 were fabricated. Each figure shows a schematic diagram of a linear array type probe, and the driving electrodes are shown as being provided on a thin polymer film or a base material of a flexible printed circuit board.
In FIG. 3, the upper side of the figure is the side where the acoustic propagation body is located, and corresponds to the acoustic operation side.

FIGS. 8 to 9 are schematic diagrams of embodiments of a composite piezoelectric ultrasonic probe having a single-layer vibrator.

Is it common for the probe shown in Figure 8? The IE electrode (31 is formed on a porous ceramic piezoelectric material), and the drive electrode (31 is formed on the other non-acoustic side through an adhesive layer (9)).
) is formed on the base of a polymer thin film or FPC board (8J). Of course, it is also possible to use only metal foil here. In the probe shown in Figure 2, the common electrode (31 is a high Base of molecular thin film or FPC board (8)
The porous ceramic piezoelectric material is bonded to the porous ceramic piezoelectric material via an adhesive layer (9) formed thereon. The acoustic non-operating side is the same as the case in FIG.

Figures 10 to 13 show two porous ceramic piezoelectric bodies.
It is a schematic diagram of an example in the case of a layer. The reason for using multiple layers, including two layers, is to connect them electrically in parallel and acoustically in series to reduce the impedance of the probe and to match it with the drive system.

In these examples, since electrodes are provided on the front and back sides of the same substrate, a patterned driving ttf& is a schematic diagram of a positioning type example, and FIG. 13 is a schematic diagram of a λ/4 type driving type example. It is a diagram. The probe shown in FIG. 10 has a common electrode 131 and 131' installed on one side of two porous ceramic piezoelectric bodies t1) and ill'. On the other hand, the nine probes shown in FIG. 11 have two porous ceramic piezoelectric bodies (1).

This is a case where a common electrode (the common electrode (3)' in the figure) is installed on either one of (1)'. Furthermore, the first
FIG. 2 shows a case where a common electrode is not provided on either of the two porous ceramic piezoelectric bodies 1°1'. 13th
The probe shown in the figure is an example in which a λ/4 plate, which also serves as a common electrode, is installed on the non-acoustic side of the probe shown in FIG.

The above figures 9 to 13 are for driving on the polymer thin film or FPC board in advance! ! This is an example of a polar pattern. Besides that! As shown in Figure 14, even if a driving electrode pattern is not formed on the polymer thin film or FPC board in advance, porous piezoelectric ceramics and the FPC board, etc. can be bonded with adhesive and then cut. Alternatively, the driving electrode pattern may be formed using the same method. (Refer to Figure 14) The drive electrode used in this example is not particularly limited, and may be, for example, one formed by vapor deposition or sputtering on a metal foil or polymer thin film, or a flexible electrode. Examples include printed circuit boards, etc. Gold 4) Although T3 is not particularly limited, gold, silver, copper, aluminum, etc. can be used. The material of the polymer thin film used for the drive electrode is not particularly limited, but examples include polynylene ester, polyethylene ester, polypropylene, polyimide,
Aromatic polyamide, polyether, polyvinyl chloride, P
Examples include VDF, PVDF copolymers, and polystyrene. These polymeric materials can be made into thin films by known methods such as casting and extrusion roll methods. Furthermore, the flexible printed circuit board is not particularly limited, but the base may be made of polyimide, polyester, etc. 9 Paper epoxy, glass epoxy → a reinforced reinforcing agent, etc. A coverlay made of polyimide, polyester, ink, etc. may be provided. .

The above-mentioned gold JA foil, polymer thin film, and flexible printed circuit board are bonded to the porous ceramic piezoelectric body using an adhesive, but at this time it is necessary to avoid having a large effect on the vibration form of the porous ceramic piezoelectric body. There is. Therefore, the thickness of the metal foil, polymer thin film or flexible printed circuit board is preferably in the range of several μm to several tens of μm.

■) Example 5 Lead oxide, zirconium oxide, and titanium oxide are used as raw materials, and the fired product obtained by compounding and firing is crushed, and a thin film is formed on it using acrylic resin and polyvinyl alcohol as a binder, and then fired. Especially density: 4.54) 1515
, porosity: 0.43. A porous ceramic having a diameter of 20 μm, a size of 40 m×25 mm, and a thickness of about 0.3 mm was obtained.

Epoxy resin (product name: Ecobond 24) or urethane resin (product name: Finnate 94-8CB) is applied uniformly to this porous ceramic, and the pores of the porous ceramic are injected and filled with each resin to make it smooth. I made it look like this. Next, a conductive epoxy resin mixed with silver powder (manufactured by Dotite Co., Ltd., trade name D-753) was applied uniformly to this surface by screen printing to a thickness of 20 μm with dimensions of 35 sa x 20 m. , 120
An electrode layer was formed by heating at °C for 2 hours. (See Figure 15).

Next, this substrate was immersed in silicone oil (manufactured by Toshiba Silicone Co., Ltd., trade name TSF451-50), and a DC electric field of 3 KV/ur was applied between both electrodes for 20 minutes at a temperature of 100°C to perform polarization treatment. I did it. More than 10 pieces coated with epoxy resin and coated with urethane resin were subjected to polarization treatment, and no dielectric breakdown occurred.

Furthermore, an ultrasonic probe was produced in the same manner as in Example 1,
The center frequency, sensitivity, and band were investigated using the same method. The results obtained are shown in Table 3.

Table 3 Using the above-mentioned porous ceramics, SiO
z (Morkyra Sheep) differential powder, P with an average particle size of 2 μm
50 each ZT powder to urethane resin! A sufficiently dispersed paint was prepared by adding the same amount and applied in the same manner.

The surface of the obtained porous ceramic was extremely smooth.

On both sides of this substrate, Ay was deposited to an average thickness of 1 μm by vacuum evaporation to form an electrode layer, and then with the above-mentioned polarization device,
A DC voltage of 4 K V/M was applied between the electrodes at 0.degree. C. for 20 minutes of polarization. No dielectric breakdown of the porous ceramic substrate was observed during polarization, and all 10 substrates subjected to polarization treatment could be obtained.

Furthermore, an ultrasonic probe was produced and evaluated in the same manner as in Example 1.

The results are shown in Table 4.

Table 4: Do not provide electrodes directly on the porous ceramic piezoelectric body as in this example, but through a resin layer! If a pole is installed, the sensitivity and band will be even better. Also, compared to direct installation, 1!
Since the material of the electrode is not limited, the electrode can be made of a material that is easy to solder, and the lead wire can be easily removed.

In the above embodiments, epoxy resin and urethane resin are used, but other resins include rubber tubes such as neobrolene, chloroprene, and silicone, adhesives such as acrylic resin and vinyl acetate, and sunalene.

Examples include polymers such as acrylic, polycarbonate, vinyl chloride, and vinyl chloride copolymers, which are dissolved in water or other organic solvents and used in the form of paints or pastes. In this case, the polymer base material must have insulation properties, and it is desirable that the volume resistivity is 10 Ωm or more. It can be used as a mixture and is not limited to A or mixed components.

In addition, when mixing inorganic or organic substance powder with the polymer base material, for example, At20s, 8i02. Metal oxides such as CaCO5°, glass beads, PbT103PbZrOs
, fine-grained glass or ceramic powder such as PZT, fine-grained polymer powder such as polyethylene, polystyrene, etc., as appropriate, or a mixture of these powders may be used as necessary. good. The desired particle size of the inorganic/organic substance powder is not particularly limited as long as it fills the pores of the porous ceramic used, and it is usually preferable to use a particle size of 10 μm or less.

〔Effect of the invention〕

According to the present invention, it is possible to provide a composite piezoelectric ultrasonic probe with high sensitivity and wide band.

[Brief explanation of the drawing]

1, 2(a), 5, 8 to 15 are schematic cross-sectional views of the present invention, FIG. 3(a) is a cross-sectional view of the ultrasonic probe, and FIG. Figure (b) and ig3 diagram (b) are amplitude diagrams,
Figure 4: Cross-sectional view of a conventional ultrasonic probe.
FIGS. 6 and 7 are impedance-frequency characteristic curve diagrams. 1.1'... Porous ceramic piezoelectric body 2 ・
...Vacancy 3, 3', 3', 3'...Electrode 4.4'...
...Plate material 5 ...Piezoelectric body 6 ...Ceramic powder or columnar ceramics 7 ...Polymer matrix S, S / , S / / ... Electrode installation material 9
．． 9'...Adhesive layer lO...-Backing material 11...Resin layer 12...Reflector plate 13...Sound #matching layer 1st Figure 3 Figure 4 Figure 5 Figure 8 Figure 9 Figure 10 Figure 11 Figure 1z Figure 13 Figure 15

Claims (5)

[Claims] (1) A composite piezoelectric ultrasonic probe equipped with a vibrator having a piezoelectric material and an electrode, characterized in that a porous ceramic piezoelectric material is used as the piezoelectric material. (2) The composite piezoelectric ultrasonic probe according to claim 1, wherein a PZT-based piezoelectric ceramic is used as the porous ceramic piezoelectric body. (3) The porous ceramic piezoelectric body has a porosity of 0.
10 to 0.75, the composite piezoelectric ultrasonic probe according to claim 1 or 2, wherein (4) Acoustic impedance (Z_A_1) is 0.7Z_
A_0≦Z_A_1≦2.2Z_A_0 (however, Z_A
Claim 1, characterized in that _0 is provided with a plate material having an acoustic impedance of a porous ceramic piezoelectric material.
Composite piezoelectric ultrasonic probe according to paragraph 2 or paragraph 3 (5) A composite piezoelectric ultrasonic probe according to claim 1, 2, or 3, characterized in that Z_A_1 is provided with a reflecting plate of Z_A_1≧10Z_A_0.