JP2557913Y2 - Ultrasonic probe - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe used in a medical field, a fish finder field, and the like, and more particularly, to an improvement in a vibrator structure thereof.

[0002]

2. Description of the Related Art Conventionally, ultrasonic probes have been used in medical equipment, fish finder and the like. In the medical field, to transmit ultrasonic waves into a living body and receive reflected waves from cancer cells, etc. to obtain information necessary for treatment, etc. An ultrasonic probe is indispensable in order to transmit a wave, receive a reflected wave from a school of fish, and extract information such as the size and distance of the school of fish.

In an ultrasonic probe used for such an application, it is necessary to focus an ultrasonic wave at a predetermined distance. For this reason, for example, an ultrasonic probe including an acoustic lens has been conventionally known.

FIG. 3 shows a configuration of an ultrasonic probe according to a conventional example. The ultrasonic probe shown in this figure is an ultrasonic probe provided with an acoustic lens. That is, a vibrator 14 formed of a piezoelectric material such as PZT on which electrodes 10 and 12 made of, for example, silver are adhered on the surface is used, and a back load 16 is provided on the electrode 12 side as viewed from the ultrasonic vibrator 14. And an acoustic lens 18 provided on the electrode 10 side. The acoustic lens 18 is a member formed of, for example, resin, glass, or the like.
The ultrasonic wave generated in the ultrasonic transducer 14 is applied to a predetermined focal point 100 by applying a voltage between the two. For this reason, the acoustic lens 18 has a convex lens shape.

[0005] The formation of the focal point 100 by the action of the acoustic lens 18 enables diagnosis and the like to be performed. In the living body, there is a portion having a different acoustic impedance from blood, which is a propagation medium of ultrasonic waves, for example, bones, cancer cells, and the like. Ultrasonic waves reflected by the bones, cancer cells, and the like cause the acoustic lens 18 to pass through. As a result, information on bones, cancer cells, and the like is obtained. That is, the size and position of the reflector can be known.

In the ultrasonic probe having such a configuration, the position of the focal point 100 depends on the shape of the surface of the acoustic lens 18. Therefore, it is difficult to change the position of the focal point 100. For this reason, the focus 100 whose position is variable
Ultrasound probes capable of forming a laser beam have been studied and put to practical use. 4 and 5 show an example configuration of such an ultrasonic probe.

In this conventional example, the ultrasonic vibrator 14
Ring-shaped ones are used. As shown in FIG. 5, the ultrasonic transducer 14 is arranged concentrically on the back load 16. The ultrasonic transducers 14 arranged as described above are all driven by the transceiver 20, and in this driving, a voltage is supplied through a plurality of delay circuits 22 having different delay amounts.

That is, the vibrator 14 in this conventional example
Are driven by signals having different application times.
That is, the time corresponding to the distance indicated by l _i in FIG _{τ i = l i / v (} v: sound velocity) only, signals applied to the vibrators 14 is delayed. The distance l _i is towards the transducer 14 in the middle than the transducer 14 in the peripheral portion is set longer, the focus 10 in place by setting the distance l _i
0 is tied. Therefore, if the delay time of the delay circuit 22 is appropriately set, the position of the focal point 100 can be changed.

[0009]

However, the ultrasonic probe capable of changing the focal length in this manner has problems such as difficulty in processing, difficulty in accurate assembly, and low transmission sensitivity. There is a point. That is, a piezoelectric ceramic material such as PZT is conventionally known as a material forming the vibrator, but it is very difficult to arrange the vibrator formed from the ceramic into a ring shape. For example, even if a relatively soft green sheet is processed into a ring shape by means of ultrasonic processing or the like, the shape after firing is not necessarily uniform, so that it is difficult to process and difficult to assemble with high accuracy. Occurs. Alternatively, there is a method of providing a groove in a plate-shaped ceramic, but this is also difficult to process.

As means for avoiding such difficulties, it is conceivable to use a vibrator made of an organic piezoelectric material such as PVDF or a composite piezoelectric material instead of piezoelectric ceramics such as PZT. Here, the composite piezoelectric material is a material formed by mixing piezoelectric ceramic powder into rubber such as epoxy, chloroprene, or urethane. In such a material, since the g constant representing the amount of electric charge generated per 1N is large, the receiving sensitivity is high, and further, the acoustic impedance Z is low, so that the matching with an ultrasonic wave propagation medium such as seawater or blood is high. Benefits can be obtained. However, when such a material is used, for example, even when the same power as that of a vibrator formed of PZT is injected, the transmission pulse becomes small, and as a result, the transmission sensitivity is lowered. SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and has as its object to realize an ultrasonic probe that ensures transmission sensitivity while realizing ease of processing and assembly. And

[0011]

In order to achieve the above object, an ultrasonic probe according to the present invention comprises a first piezoelectric vibrator formed in a plate shape and a first piezoelectric vibrator formed in a ring shape. And a plurality of second piezoelectric vibrators concentrically arranged on the piezoelectric vibrator, wherein the second piezoelectric vibrator is formed of an organic piezoelectric material. I do.

A second aspect of the present invention is characterized in that the second piezoelectric vibrator is formed of a composite piezoelectric material mixed and produced by a piezoelectric ceramic powder and rubber.

Further, a third aspect of the present invention provides a means for supplying a voltage to the first piezoelectric vibrator and transmitting an ultrasonic wave, and delaying a signal relating to the ultrasonic wave received by the second piezoelectric vibrator. Means for forming a focal point.

According to a fourth aspect, the first piezoelectric vibrator is composed of Pb (Z
r, Ti) O ₃ : Lead zirconate titanate (PZT), B
aTiO ₃ : formed from either barium titanate or PbTiO ₃ : lead titanate.

In a preferred embodiment, the second piezoelectric vibrator is a PVD.
F: polyvinylidene fluoride, PVDF copolymer, P (V
DCN / VAc): a copolymer of vinylidene cyanide and vinyl acetate or P (VDF / TrFE ) : a copolymer of vinylidene fluoride and ethylene trifluoride.

According to a sixth aspect of the present invention, in the material forming the second piezoelectric vibrator, the rubber is NBR: a copolymer of butadiene and acrylontrile, SBR: a radical copolymer of butadiene and styrene, or urethane rubber. Or any one of the following.

[0017]

According to the first aspect of the present invention, the second piezoelectric vibrator is formed of an organic piezoelectric material. Organic piezoelectric material is P
It is easier to process than a piezoelectric ceramic material such as ZT, and can be formed into a film, for example.
As a result, an ultrasonic probe that is easier to process and assemble can be obtained.

In the second aspect, the second vibrator is formed of a so-called composite piezoelectric material. Since this composite piezoelectric material is also formed using rubber as a base material, it has the effect of facilitating processing and assembly as in the case of the organic piezoelectric material according to the first aspect.

In the present invention, the first piezoelectric vibrator is used for transmitting ultrasonic waves, and the second piezoelectric vibrator is used for receiving ultrasonic waves. The signal obtained by receiving the wave is
Delayed to form focus. As described above, since the focus is formed by the signal delay on the receiving side, the focus can be set by setting the delay amount.

According to a fourth aspect, the first piezoelectric vibrator is formed from a piezoelectric ceramic material such as PZT. PZT
Is a material with good transmission sensitivity.
As a result, it is possible to secure good transmission sensitivity as well as the easiness of processing and assembly obtained in the first or second aspect.

According to a fifth aspect, the second piezoelectric vibrator is formed of an organic piezoelectric material such as PVDF. Organic piezoelectric materials have an acoustic impedance closer to ultrasonic propagation media such as blood and seawater than piezoelectric ceramic materials such as PZT,
Further, it has a property that the g constant is large. Therefore, an ultrasonic probe having high matching of the ultrasonic wave propagation medium and high reception sensitivity can be obtained.

In a sixth aspect, the second piezoelectric vibrator is formed of a mixed material such as piezoelectric ceramic powder and NBR. This material is similar to an ultrasonic wave propagation medium having an acoustic impedance and has a large g constant, like PVDF and the like. Therefore, the same effect as that of the fifth aspect can be obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The same components as those in the conventional example shown in FIGS. 3 to 5 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a circuit configuration of an ultrasonic probe according to an embodiment of the present invention. FIG. 2 shows the focus formation principle of this embodiment.

The embodiment shown in these figures has a configuration using a ring-shaped vibrator, similarly to the conventional example shown in FIG. That is, the vibrator 14-2 has a ring-like shape and is arranged concentrically. However, these transducers 14-2 are not disposed on the back load 16 but on the ultrasonic transducer 14-1 having a thickness of, for example, about 400 to 500 μm.

The ultrasonic transducer 14-1 is formed of PZT in this embodiment. An electrode 12-1 of silver or the like is provided on the lower surface of the plate-shaped ultrasonic transducer 14-1, and an electrode 10-1 is provided on the upper surface. Electrode 14-1
Although not shown, a back load is arranged below the
-1, the ultrasonic vibrator 14-2 has the conductive adhesive 24
It is adhered by. The ultrasonic transducer 14-2 is arranged concentrically on the ultrasonic transducer 14-1. The electrode 12-2 is provided on the lower surface of the ultrasonic transducer 14-2, and the electrode 10-2 is provided on the upper surface.

In this embodiment, the ultrasonic vibrator 14-
2 is, for example, 300 μm when vibrating at 3 to 5 MHz.
This is a vibrator made of PVDF having a thickness of about m. Therefore, it is excellent in workability as compared with the case where it is formed from PZT. For example, a ring-shaped ultrasonic transducer 14-2 can be easily obtained by punching a film-shaped PVDF material. The vibrator 14-2 thus obtained can be bonded onto the ultrasonic vibrator 14-1 with the conductive adhesive 24 made of epoxy resin or the like. The width of the vibrator 14-2 is about 0.5 to 1 mm, and the interval between the vibrators 14-2 is about 0.1 to 0.3 mm.

As described above, as a result of the vibrators 14-1 and 14-2 being bonded by the adhesive 24, the electrodes 10-1 and 12-2
Becomes conductive. Accordingly, the electrodes 10-1 and 12
-2 can be treated as a common electrode. In this embodiment, a voltage is applied from the transmitter 26 between the common electrode and the electrode 12-1, and a signal appearing between the common electrode and the electrode 10-2 is transmitted to the delay circuit 22 and the signal synthesis circuit 28. The data is taken into the receiver 30 via the receiver.

That is, in this embodiment, PZT
Is used exclusively for transmission. As a result, a decrease in transmission sensitivity is prevented. That is, PZT is a material having high transmission sensitivity, is resistant to mechanical distortion, and can increase the injected power. As a result, the transmission sensitivity of the ultrasonic probe is secured and transmission is possible. On the other hand, in this embodiment, the ultrasonic transducer 14-2 formed from PVDF is exclusively used for reception. PVD
The acoustic impedance of F is, for example, 3 to 5 × 10 ⁶ kg.
/ M ² s, which is close to the acoustic impedance of blood and seawater of 1.5 × 10 ⁶ kg / m ² s. This is compared to the acoustic impedance of PZT of 35 × 10 ⁶ kg / m ² s.
It is much closer to blood, etc.

Therefore, in this embodiment, the transmission sensitivity is ensured and the acoustic matching with the ultrasonic wave propagation medium is improved. Furthermore, PVDF has a larger g-constant than PZT, and therefore has higher receiving sensitivity.

The delay circuit 22 is provided with the vibrator 1 as in the prior art.
This is a circuit for delaying the signal according to 4-2 by a time τ _i corresponding to the distance l _i shown in FIG. However, in this embodiment, unlike the conventional example, a delay is applied on the receiving side. Therefore, as shown by the arrow in FIG. 2, in the case of transmitting a wave, an ultrasonic wave is emitted to the front surface, and a focal point 100 is formed on the receiving side. The signal combining circuit 28 is a circuit that combines the signals obtained from the plurality of delay circuits 22 and supplies the combined signal to the receiver 30.

Therefore, in this embodiment, the function of changing the focus in the conventional example can be ensured. Thereby, a highly usable ultrasonic probe can be realized.

In the above description, the vibrator 14
Although it is assumed that PZT is used as the material of -1 and PVDF is used as the material of the vibrator 10-2, the present invention is not limited to these materials. For example, the vibrator 14
-1 are formed of BaTiO ₃ , PbTiO
A piezoelectric ceramic material such as ₃ may be used. As a material for forming the second piezoelectric vibrator 14-2, a PVDF copolymer, P (VDCN / VAc), P (VDF / TrFE)
Or a composite piezoelectric material in which piezoelectric ceramic powder is mixed into NBR, SBR, urethane rubber, or the like.

[0034]

[Effect of the Invention] As described above, claim 1 of the present invention
According to the method, the second piezoelectric vibrator is formed of an organic piezoelectric material, so that an ultrasonic probe that can be easily processed and assembled can be obtained.

In the second aspect, since the second piezoelectric vibrator is formed of a so-called composite piezoelectric material, an ultrasonic probe which is easy to process and assemble can be obtained as in the first aspect. it can.

In the third aspect, the focus is formed by delaying the signal on the receiving side, so that the focus can be set by setting the amount of delay.

In the fourth aspect, since the first piezoelectric vibrator is formed from a piezoelectric ceramic material such as PZT, an ultrasonic probe having high transmission sensitivity can be obtained.

According to the fifth aspect, since the second piezoelectric vibrator is formed from an organic piezoelectric material such as PVDF, an ultrasonic probe having high reception sensitivity and high acoustic matching can be obtained.

According to the sixth aspect, since the second piezoelectric vibrator is formed from a mixed material of the piezoelectric ceramic body and the NBR, the same effect as the fifth aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a circuit configuration of an ultrasonic probe according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a principle of forming a focus in this embodiment.

FIG. 3 is a diagram showing an ultrasonic probe according to a first conventional example.

FIG. 4 is a diagram showing a configuration of an ultrasonic probe according to a second conventional example.

FIG. 5 is a perspective view showing a configuration of an ultrasonic probe according to this conventional example.

[Explanation of symbols]

 10-1, 10-2, 12-1, 12-2 Electrodes 14-1, 14-2 Ultrasonic transducer 22 Delay circuit 26 Transmitter 30 Receiver 100 Focus

Claims (6)

(57) [Scope of request for utility model registration] A first piezoelectric vibrator formed in a plate shape; and a plurality of second piezoelectric vibrators formed in a ring shape and arranged concentrically on the first piezoelectric vibrator. An ultrasonic probe, wherein the second piezoelectric vibrator is formed from an organic piezoelectric material. 2. A first piezoelectric vibrator formed in a plate shape and a second piezoelectric vibrator formed in a ring shape and disposed on the first piezoelectric vibrator.
A piezoelectric vibrator comprising:
Wherein the piezoelectric vibrator is formed of a composite piezoelectric material mixed and produced by a piezoelectric ceramic powder and rubber. 3. The ultrasonic probe according to claim 1, wherein a means for supplying a voltage to the first piezoelectric vibrator to transmit an ultrasonic wave, and receiving the voltage by the second piezoelectric vibrator. Means for forming a focal point by delaying a signal related to the ultrasonic wave. 4. The ultrasonic probe according to claim 1, wherein the first piezoelectric vibrator is made of Pb (Zr, Ti) O ₃ , B
An ultrasonic probe formed of either aTiO ₃ or PbTiO ₃ . 5. The ultrasonic probe according to claim 1, wherein the second piezoelectric vibrator is made of PVDF, PVDF copolymer, or PDF.
An ultrasonic probe formed from any one of (VDCN / VAc) and P (VDF / TrFE). 6. The ultrasonic probe according to claim 2, wherein the second piezoelectric vibrator is configured to convert the piezoelectric ceramic powder into NBR and SB.
An ultrasonic probe produced from a material mixed with either R or urethane rubber.