JPH04282138A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To offer the ultrasonic probe which can form alternately and independently two resonance states, can execute a wide-band conversion by a simple constitution, and also, whose difficulty for manufacture is comparatively small and whose practical use is facilitated, and also, whose satisfactory characteristic is obtained. CONSTITUTION:A back board 13 being a first back material is provided on the back of an ultrasonic vibrator 11. This back board 13 becomes a state fixed acoustically to the ultrasonic vibrator 11 in a first position A. The acoustic impedance of the back board 13 is higher than the acoustic impedance of the ultrasonic vibrator 11. The back board 13 turns by 90 deg. clockwise centering around a turning shaft 15 in the figure from a first position A by operating an operating control 17, and can move to a second position B being in a horizontal state. Furthermore, the inside of a housing 10 is filled with a liquid-like back medium 18 being a second back material. The acoustic impedance of this back medium is lower than the acoustic impedance of the ultrasonic vibrator 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic deep transducer used in ultrasonic diagnostic equipment and the like, and more particularly to an ultrasonic deep transducer for transmitting and receiving ultrasonic waves in a wide band of frequencies.

0002

[Prior Art] Currently, ultrasonic diagnosis using a deep ultrasonic probe is widely used as a simple, safe, and economical imaging method, and the target area of the examination is almost the whole body. There is. However, especially in the examination of living organisms, since the frequency varies depending on the object to be examined, a wide variety of ultrasonic depth probes are required for each object to be examined. For example, select a deep probe with a high frequency (5 to 10 MHz) to examine shallow parts of the living body, and select a deep probe with a low frequency (3.5 to 5 MHz) to examine deep parts.
There is the inconvenience of using different ultrasonic depth probes depending on the object to be examined, such as selecting a deep probe. Therefore, there is a strong demand for a wide-band ultrasonic transducer that can transmit and receive from low to high frequencies with a single ultrasonic deep probe.

Up to now, several ultrasonic probes capable of transmitting and receiving multiple frequencies have been proposed. They include:
For example, a type in which piezoelectric vibrators with different resonance frequencies are stacked (Japanese Patent Laid-Open No. 58-73861, Japanese Patent Laid-Open No. 63-17)
2600, JP 63-173954, JP 63-175761, etc.), types with improved acoustic matching layers (JP 63-255044),
Alternatively, there is a type (Japanese Unexamined Patent Publication No. 62-68000) in which piezoelectric vibrators having different resonance frequencies are arranged alternately.

0004

[Problems to be Solved by the Invention] However, both methods have problems such as distortion in the frequency response band, deterioration of ultrasonic sound field characteristics, or difficulty in manufacturing due to complicated structure. there were.

For example, in a laminated type ultrasonic deep probe, it is necessary to laminate a number of piezoelectric vibrators with different frequencies.
It is complicated to manufacture and is also uneconomical. Furthermore, regarding the characteristics, since piezoelectric vibrators with different resonance frequencies are stacked in the direction of transmitting and receiving ultrasonic waves, the piezoelectric vibrators act on each other to interfere with the propagation of ultrasonic waves when transmitting and receiving, resulting in good results. cannot be obtained.

A type in which piezoelectric vibrators having different resonance frequencies are arranged alternately can be used as an array type ultrasonic probe, but the arrangement density of the vibrators of one frequency is low. Therefore, the principle of increasing the arrangement density, which is the most important aspect of an array type deep probe, and forming a highly directional transmitting and receiving ultrasonic sound field that suppresses grating lobes as much as possible.
This contradicts the principle and causes deterioration of the characteristics.

[0007] Therefore, as a method different from the above method,
An array-type deep probe has also been proposed in which the thickness of the piezoelectric vibrator is continuously changed in the direction perpendicular to the scanning direction, so that the resonant frequency can be continuously varied in this direction (Japanese Patent Laid-Open No. 58 −
22040). However, this method also did not provide good frequency characteristics and had problems in terms of sensitivity. Further, there is a problem in that it is difficult to manufacture such a piezoelectric vibrator, and it is difficult to put it into practical use.

The present invention has been made in view of the above problems, and its purpose is to be able to form two resonant states alternately and independently, to achieve a wide band with a simple configuration, and to reduce manufacturing costs. The object of the present invention is to provide an ultrasonic deep probe that is easy to put into practical use with relatively little difficulty, has good characteristics, and can be applied to all types of systems.

[0009]

[Means for Solving the Problems] An ultrasonic deep probe according to the present invention has an ultrasonic transducer and an acoustic impedance higher than that of the ultrasonic transducer, and has a a first backing material that is acoustically coupled; a second backing material that has a lower acoustic impedance than the ultrasonic transducer and is acoustically coupled to the back surface of the ultrasonic transducer; and coupling switching means for switching acoustic coupling to the ultrasonic transducer to either the first backing material or the second backing material.

[0010] The first backing material is a backing plate having a size corresponding to at least the ultrasonic transducer, and the second backing material is a liquid-like material filled on the back side of the ultrasonic transducer. A backing medium of

[0011] The coupling switching means moves the back plate between a first position where the back plate is acoustically coupled to the ultrasonic transducer and a second position which is spaced apart from the ultrasonic transducer. and when the back plate moves to a second position, the back medium is acoustically coupled to the ultrasonic transducer.

The back plate moving means attaches the back plate to a support plate, and attaches this support plate to a rotating shaft having an operating knob, and moves the back plate to the first position by operating the operating knob. Preferably, the rotation mechanism is configured to rotate between the second position and the second position.

The ultrasonic transducer may be a single transducer, or may be of a linear array type using a plurality of divided transducers.

With such a configuration, the ultrasonic deep probe of the present invention has a first backing material having an acoustic impedance higher than the acoustic impedance of the ultrasonic transducer, and a first backing material having an acoustic impedance lower than the acoustic impedance of the ultrasonic transducer. Either one of the second backing material and the second backing material can be made to function independently as a backing material of the ultrasonic transducer. Therefore, states of λ/4 resonance and λ/2 resonance can be formed independently and alternately, and ultrasonic waves of two independent frequencies can be efficiently transmitted and received.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIGS. 1 and 2 show the configuration of an ultrasonic deep probe 1 according to an embodiment of the present invention. FIG. 1 shows the state of λ/4 resonance, and FIG. 2 shows the state of λ/2 resonance. each represents. Further, FIG. 3 shows the configuration of the front surface of the ultrasonic deep probe 1, that is, the configuration in the ultrasonic transmission and reception direction. This ultrasonic probe 1 has a plate-shaped ultrasonic transducer 11 on the front side of a housing 10 (on the left side in the figure). This ultrasonic transducer 1
1 is acoustically fixed to a front protection plate 12 which also serves as an acoustic matching layer. Although not shown, a negative electrode (not shown) is formed on the front surface of the ultrasonic transducer 11, and a positive electrode is formed on the back surface, and each is electrically connected to an external transmitting/receiving circuit by a lead wire.

A back plate 13 serving as a first back material is disposed on the back of the ultrasonic transducer 11. This back plate 13
is the ultrasonic transducer 1 at the first position A shown in FIG.
1 and is acoustically fixed. Back plate 13
The acoustic impedance of the ultrasonic transducer 11 is higher than that of the ultrasonic transducer 11.

This back plate 13 is fixed on a support plate 14, and this support plate 14 is connected to a rotation shaft 15. The rotation shaft 15 is rotatably supported at one end by a bearing portion 16, and has an operating knob 17 provided at the other end. By operating this operating knob 17, the back plate 13 can be rotated 90 degrees clockwise from the first position A around the rotation axis 15 in the figure, and can be moved to the second position B in the horizontal state. ing.

The inside of the casing 10 is further filled with a liquid backing medium 18 as a second backing material. The acoustic impedance of this back surface medium 19 is
The acoustic impedance is lower than that of 1. Housing 1
A diffused reflector 19 is disposed on the rear surface side of the inside of the ultrasonic transducer 11, facing the ultrasonic transducer 11. The diffuse reflector 19 diffusely reflects the ultrasonic waves transmitted to the back surface of the ultrasonic transducer 11 and transmitted through the back surface medium 18, and is made of, for example, rubber or epoxy resin.

As the ultrasonic vibrator 11, a ceramic piezoelectric material such as silconate titanate (PZT) or a polymer piezoelectric material such as polyvinyldene fluoride (PVDF) is used. Further, as the back plate 13, copper (C
A metal plate made of iron (Fe), tungsten (W), etc. is used, and as the back medium 18, for example, silicone oil or the like is used. Silconate titanate (PZT)
) has an acoustic impedance of 30×106 kg/m2
In this case, the back plate 13 should be made of tungsten with an acoustic impedance of 100×106 kg/m2・s, and the back medium 18 should be made of silicone oil with an acoustic impedance of 1×106 kg/m2・s. is preferred. Also, the acoustic impedance of polyvinylidene fluoride (PVDF) is 3 x 106 kg
/m2 ・s, and in this case, the acoustic impedance of the back plate 13 is 45×106 kg/m2 ・s
It is also preferable to use silicone oil as the backing medium 18.

With such a configuration, in the ultrasonic deep transducer 1 of this embodiment, since the back plate 13 is in the first position A in the state shown in FIG. and transmit and receive ultrasonic waves of a first frequency. From this state, when the operating knob 17 is rotated clockwise in FIG. 1 and moved to the second position B as shown in FIG. Both are acoustically coupled. Therefore, in this state, transmission and reception can be performed using ultrasonic waves of the second frequency.

As described above, in the ultrasonic probe 1 of this embodiment, the states shown in FIGS. 1 and 2 can be alternately set simply by operating the operating knob 17. Note that since the back medium 18 is in a liquid state, the first position A and the second position B of the back plate 13 are
Movement between the two is smooth.

Next, the acoustic characteristics of the ultrasonic transducer 11 in the ultrasonic deep probe 1 of this embodiment, that is, the difference in resonance frequency during transmission and reception, will be explained in detail.

First, in the state shown in FIG.
A back plate 13 is held and pressed at the first position A, and the ultrasonic transducer 11 and the back plate 13 are acoustically coupled through an extremely thin layer of the back medium 18. There is. However, since this layer is extremely thin, the back plate 13 effectively acts as a back material for the ultrasonic transducer 11 .

As described above, the back plate 1 has an acoustic impedance higher than that of the ultrasonic transducer 11.
It is well known that when the ultrasonic transducer 11 acoustically acts as a backing material, the ultrasonic transducer 11 enters a state of so-called λ/4 resonance. At this time, most of the ultrasonic waves transmitted to the back surface of the ultrasonic transducer 11 are reflected by the back plate 13 and transmitted to the front surface. The ultrasonic waves slightly transmitted through the back plate 13 and the support plate 14 are absorbed and attenuated by the back medium 18, so that the ultrasonic waves transmitted to the front surface are not adversely affected.

Next, in the state shown in FIG.
A back surface medium 18 whose acoustic impedance is lower than that of the ultrasonic transducer 11 is formed on the back surface of the ultrasonic transducer 11, and in this case,
It is well known that the ultrasonic transducer 11 is in a state of so-called λ/2 resonance. The ultrasonic waves transmitted to the back surface of the ultrasonic transducer 11 are absorbed and attenuated by the back surface medium 18 . The ultrasonic waves that have slightly transmitted through this back medium 18 are diffusely reflected by the diffuse reflector 19 and are reflected again by the ultrasonic transducer 11.
Since the ultrasonic waves reach the front surface and cause multiple reflections, there is no adverse effect on the ultrasonic waves transmitted to the front surface.

As described above, the ultrasonic deep probe 1 of this embodiment
When the ultrasonic transducer 11 is in the state shown in FIG. 1, it becomes λ/4 resonance, and in the state shown in FIG. 2, it alternates with the λ/2 resonance state. Here, since λ/2 resonance resonates at twice the frequency of λ/4 resonance, in the state of FIG. 2, ultrasonic waves with twice the frequency as in the state of FIG. 1 can be transmitted and received. Specifically, if the ultrasonic transducer 11 is set to have a resonant frequency of 3.5 MHz in the state shown in FIG. 1, it will have a resonant frequency of 7 MHz in the state shown in FIG. Therefore, this ultrasonic deep probe 1 can independently and efficiently transmit and receive ultrasonic waves of frequencies f and 2f simply by operating the operating knob 17.

FIG. 4 shows the configuration of an ultrasonic probe 2 according to another embodiment of the present invention. In this embodiment, an ultrasonic transducer 11 is divided into a plurality of transducers 20 and arranged linearly, and is a so-called linear array type ultrasonic probe. These divided vibrators 20 are similar to the above embodiment,
It is acoustically fixed to a front protection plate 12 which also serves as a matching layer. The rest of the structure is the same as the embodiment shown in FIG.
The explanation will be omitted. The ultrasonic deep probe 2 of this embodiment also has two frequencies, f and 2f, by simply operating the operating knob 17.
One frequency can be selected.

The present invention has been explained above with reference to examples.
The present invention is not limited to the above embodiments, and can be modified in various ways without changing the gist thereof. For example, in the above embodiment, the back plate 13 is attached to the support plate 14 fixed to the rotation shaft 15 of the operation knob 17, but the back plate 13 may be directly connected to the support shaft 15. good. Further, in the above embodiment, the back plate 13
The second position is the position B shown in FIG. 1, that is, the horizontal position along the bottom surface of the housing 10. By configuring the face plate 13 to rotate horizontally, it may be positioned along the side surface of the housing 10. Furthermore, the means for switching the acoustic coupling between the back plate 13 or the back medium 18 with respect to the ultrasonic transducer 11 is not limited to the above-mentioned rotating mechanism;
Any structure may be used as long as the back plate 13 and the back medium 18 are acoustically coupled alternately and independently.

[0030]

As explained above, according to the ultrasonic deep probe according to claims 1 to 5, the first backing material having an acoustic impedance higher than the acoustic impedance of the ultrasonic transducer; The second backing material having an acoustic impedance lower than the acoustic impedance of Ultrasonic waves can be transmitted and received efficiently and broadband can be achieved. In addition, it has a simple configuration, has relatively few manufacturing difficulties, is easy to put into practical use, and has good characteristics, and can be applied to all types of ultrasonic probes such as linear array type. be.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing the configuration of an ultrasonic deep probe according to an embodiment of the present invention, and showing a state of λ/4 resonance.

FIG. 2 is a longitudinal cross-sectional view showing a state of λ/2 resonance in the ultrasonic deep probe of FIG. 1;

FIG. 3 is a front view of the ultrasonic probe of FIG. 1;

FIG. 4 is a front view showing the configuration of an ultrasonic probe according to another embodiment of the present invention.

[Explanation of symbols]

1, 2 Ultrasonic depth probe 10 Housing 11 Ultrasonic transducer 12 Front protection plate 13　Back plate 17 Operation knob 18 Back medium 19 Diffuse reflector 20 Oscillator

Claims (5)

[Claims] 1. An ultrasonic transducer; a first backing material having a higher acoustic impedance than the ultrasonic transducer and acoustically coupled to a back surface of the ultrasonic transducer; a second backing material that has a lower acoustic impedance than the ultrasound transducer and is acoustically coupled to the back surface of the ultrasound transducer; and a second backing material that acoustically couples to the ultrasound transducer; 1. An ultrasonic deep probe comprising: coupling switching means for switching to either one of the backing material and the second backing material. 2. The first backing material is a backing plate having a size corresponding to at least the ultrasonic transducer, and the second backing material is a backing plate having a size corresponding to at least the ultrasonic transducer, and the second backing material is a liquid-like material filled on the back side of the ultrasonic transducer. The ultrasonic deep probe according to claim 1, which is a backing medium of. 3. The coupling switching means connects the back plate to
a back plate moving means for moving between a first position acoustically coupled to the ultrasonic transducer and a second position spaced apart from the ultrasonic transducer; 2
2. The ultrasonic transducer according to claim 2, wherein the back surface medium is acoustically coupled to the ultrasonic transducer when the ultrasonic transducer is moved to the position.
Ultrasonic deep probe as described. 4. The back plate moving means attaches the back plate to a support plate, and attaches the support plate to a rotation shaft having an operating knob, and moves the back plate to a first position by operating the operating knob. 4. The ultrasonic deep probe according to claim 3, wherein the ultrasonic deep probe is a rotating mechanism for rotationally moving between the first position and the second position. 5. The ultrasonic deep probe according to claim 1, wherein the ultrasonic transducer is composed of a plurality of divided transducers.