JP3659780B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, particularly to control of the ultrasound beam by the acoustic velocity variable.
[0002]
[Prior art]
A one-dimensional array transducer (1D transducer) is an array of a plurality of ultrasonic transducer elements. An electronic focus or electronic scanning (for example, electronic sector scanning) of the ultrasonic beam is performed by giving a predetermined delay amount to each of the transmission signal and reception signal supplied to each ultrasonic vibration element constituting the array transducer.
[0003]
The 1.5D transducer is formed by arranging a plurality of one-dimensional array transducers along the elevation direction (a direction orthogonal to the electronic scanning direction and corresponding to the slice direction). Then, the beam forming in the elevation direction can be performed by electronically performing delay control on each array transducer. That is, while the acoustic lens has a fixed focus, according to this method, the focus can be varied in the elevation direction.
[0004]
A two-dimensional array transducer (2D transducer) is an array of ultrasonic transducer elements two-dimensionally and can freely scan an ultrasonic beam two-dimensionally. In particular, this 2D transducer is used when capturing three-dimensional echo data. Conventionally, in order to two-dimensionally scan an ultrasonic beam, an electronic scanning method has been applied to both the X direction and the Y direction.
[0005]
[Problems to be solved by the invention]
However, in the past, 1.5D transducers and 2D transducers rely on electronic control of transmission / reception signals for focusing and scanning of ultrasonic beams, and transmission / reception with a large number of signal lines for individually controlling each element. A vessel is required. For this reason, there has been a problem that the ultrasonic probe becomes extremely difficult, the probe cable becomes extremely thick, and the apparatus becomes large-scale.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to realize a 1.5D vibrator and a 2D vibrator in which the number of signal lines is reduced.
[0007]
Another object of the present invention is to realize a new beam forming method using a control of the ultrasound propagation velocity with electronic delay equivalent to the function of transmitting and receiving signals that have been conventionally used.
[0009]
[Means for Solving the Problems]
In a desirable aspect of the present invention, a plurality of ultrasonic vibration elements and a plurality of elements that are provided above the plurality of ultrasonic vibration elements and through which ultrasonic waves transmitted or received by the ultrasonic vibration elements pass. A plurality of sound speed control elements having a function of individually adjusting the sound speed of ultrasonic waves in each element, and a plurality of matching layers provided on the upper side of the plurality of sound speed control elements, An acoustic delay is realized in the ultrasonic wave passing direction by individually controlling the sound velocity of the ultrasonic wave in each of the sound velocity control elements. Preferably, each matching layer includes a stacked first matching layer and second matching layer.
[0010]
According to the above configuration, the sound speed of the ultrasonic wave passing through the sound speed control element (sound speed control medium) is controlled, thereby realizing acoustic delay control. The sound velocity control element is provided in a passage path of the ultrasonic wave transmitted from the ultrasonic vibration element or the received ultrasonic wave.
[0011]
Desirably, the sound velocity control element has a piezoelectric material as a main component. When an ultrasonic wave passes through the piezoelectric material, the elastic constant of the piezoelectric material can be changed by the impedance connected to the piezoelectric element. Sound speed control can be performed using this property. The following relational expression shows the relationship between the respective elastic constants when the impedance connected to the piezoelectric element corresponds to a short circuit and when the impedance corresponds to infinity, that is, an open circuit.
[0012]
1-K * K = s ^D / s ^E
Here, K = electromechanical coupling coefficient s ^D = elastic coefficient (compliance) when electrodes are short-circuited
s ^E = elastic coefficient when the electrode is open (compliance)
Of course, other elements that can electrically control the sound speed can be used as the sound speed control element.
[0013]
In a preferred aspect of the present invention, the sound speed control element is provided with a first electrode and a second electrode, and a variable impedance circuit is connected between the first electrode and the second electrode.
In a preferred aspect of the present invention, the second electrode is provided between the sound velocity control element and the ultrasonic vibration element, and the second electrode constitutes a common ground electrode. By sharing the electrodes, the number of parts of the vibrator can be reduced, and the structure can be simplified in extracting the signal lines.
[0015]
An ultrasonic diagnostic apparatus according to the present invention is provided with an ultrasonic vibration element group composed of a plurality of two-dimensionally arranged ultrasonic vibration elements, and is provided for each of the ultrasonic vibration elements. Electronic control means for performing electronic scanning or electronic focusing in the x direction for each of a plurality of sound velocity control elements having a function of adjustment and a y direction row aligned in the y direction among the plurality of ultrasonic vibration elements And, for each y-direction row aligned in the x direction among the plurality of ultrasonic vibration elements, the sound speed of the sound speed control element row corresponding to the x-direction row is controlled to perform focus or beam angle scanning. Sound speed control means. That is, beam control is executed using sound speed adjustment in the y direction. In the x direction, beam control is performed using electronic control (for example, linear scanning).
[0016]
An ultrasonic diagnostic apparatus according to the present invention is provided with an ultrasonic vibration element group composed of a plurality of two-dimensionally arranged ultrasonic vibration elements, and is provided for each of the ultrasonic vibration elements. The angle of the beam in the x direction by electronic delay control in the x direction for each of the plurality of sound speed control elements having a function of adjustment and the y direction row aligned in the y direction among the plurality of sound speed control elements. An electronic delay control means for performing scanning or focusing, and a sound speed of the sound speed control element array corresponding to the x direction array for each of the plurality of ultrasonic vibration elements arranged in the x direction along the x direction. And a sound speed control means for controlling and performing a focus in the y direction or an angle scan of the beam. That is, beam control is performed by electronic control (for example, sector scanning) in the x direction, and beam control is performed by sound velocity control in the y direction.
[0017]
According to the present invention, while the conventional 2D vibrator requires N × N signal lines (N is the number of vibration elements in the X direction and the Y direction), control is performed using N + N signal lines. Since this is possible, the number of signal lines can be greatly reduced. Further, the manufacturing cost can be reduced, and the ultrasonic probe can be further downsized. With respect to the 1.5D vibrator, the number of signal lines can be reduced to (N + M) / (N × M) (where N is the number of elements and M is the number of divisions in the elevation direction) as compared with the conventional case.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0019]
FIG. 1 shows a main configuration of an ultrasonic probe and an ultrasonic diagnostic apparatus according to the present invention. The principle of the present invention will be described with reference to FIG.
[0020]
The ultrasonic probe 10 is an ultrasonic probe that is used in contact with a body surface or inserted into a body cavity. The ultrasonic probe 10 is connected to the apparatus main body 12 by a cable.
[0021]
In the ultrasonic probe 10, the piezoelectric vibration element 14 for transmitting and receiving ultrasonic waves is composed of a piezoelectric material such as PZT, and a signal side electrode 16 is provided on the lower surface side thereof. A ground-side lead 18 is provided on the upper surface side. A backing 20 is joined to the lower side of the signal side electrode 16. The backing 20 is a member that absorbs ultrasonic waves emitted backward from the piezoelectric vibration element 14. A sound speed control element 22 is provided above the ground-side lead 18. The sound speed control element 22 functions as a sound speed control medium and has a function of adjusting the sound speed of the ultrasonic wave passing through the sound speed control element 22. A control-side lead 24 is provided on the upper surface of the sound speed control element 22. As shown in FIG. 1, the ground-side lead 18 functions as a common electrode for the piezoelectric element 14 and the sound speed control element 22.
[0022]
When a voltage is applied between the signal side electrode 16 and the ground side lead 18, an ultrasonic wave is generated by the piezoelectric vibration element 14. On the other hand, when an ultrasonic wave is received by the piezoelectric vibration element 14, the signal side electrode A voltage is generated between 16 and the ground-side lead 18. A transmitter / receiver 32 is connected between the signal side electrode 16 and the ground side lead 18, a transmission signal is supplied to both electrodes by the transmitter / receiver 32, and a reception signal from both electrodes is transmitted / received to the transmitter / receiver 32. Received by. The transceiver 32 is a circuit that performs so-called electronic delay control.
[0023]
A sound speed control element 22 is sandwiched between the control-side lead 24 and the ground-side lead 18, and an impedance control unit 30 is connected to both electrodes. The impedance control unit 30 is a circuit that controls the elastic speed of the sound speed control element 22 by adjusting the magnitude of the impedance of the impedance circuit incorporated therein, thereby controlling the sound speed. In the present embodiment, the impedance control unit 30 is located on the apparatus main body side, but it is of course possible to incorporate it in the ultrasonic probe.
[0024]
In the present embodiment, the sound speed control element 22 is constituted by a piezoelectric body. Piezoelectric bodies generally have a piezoelectric reaction, and have the property that the sound velocity of ultrasonic waves passing through the inside varies depending on the electrical load (impedance) connected to the electrodes of the piezoelectric body. In the present embodiment, the speed of the ultrasonic wave is controlled by effectively utilizing the property. Therefore, the impedance control unit 30 controls the speed of sound in the sound speed control element 22 as a result by controlling the magnitude of the impedance it has. In the above embodiment, a piezoelectric body is used as the sound speed control element 22, but other sound speed control media may be used as a matter of course.
[0025]
A first acoustic matching layer 26 and a second acoustic matching layer 28 are provided above the control-side lead 24. Each of the matching layers 26 and 28 has a function of matching the acoustic impedance. An acoustic lens or the like is disposed on the second acoustic matching layer 28 as necessary.
[0026]
As described above, when an ultrasonic wave is generated by the piezoelectric vibration element 14, the ultrasonic wave passes through the sound speed control element 22, and the sound speed at the time of the passage is controlled by the impedance control unit 30. Of course, even at the time of reception, the sound velocity of the ultrasonic wave that passes through the sound velocity control element 22 and is received by the piezoelectric vibration element 14 is controlled by the impedance control unit 30.
[0027]
Therefore, by providing a plurality of assemblies shown in FIG. 1 and changing the sound speed between the assemblies, it is possible to acoustically realize conventional beam forming such as electronic focusing and electronic scanning. That is, the present invention is preferably applied to the above-described 1.5D vibrator, 2D vibrator, and the like. Of course, the present invention can be applied to a single vibrator.
[0028]
FIG. 2 shows a configuration example of the impedance control unit 30. This circuit configuration example is the simplest example, and of course, other circuit configurations can be adopted. The sonic control element 22 is sandwiched between the control-side lead 24 and the ground-side lead 18, and an impedance circuit 32 is connected to both electrodes. In this example, the impedance circuit 32 is composed of a variable resistor, and the impedance is controlled by controlling the resistance value of the variable resistor with a control signal. As another configuration of the impedance circuit 32, for example, a variable inductance can be used. When a plurality of assemblies shown in FIG. 1 are provided, for example, a circuit configuration as shown in FIG. 3 can be adopted. An impedance circuit 32 is provided for each sound speed control element 22, and these impedance circuits 32 are controlled by a sound speed controller 34. For example, if the sound speed of the elements on both sides is increased with respect to the center element, as a result, the ultrasonic waves are emitted from both sides first, while the ultrasonic waves are emitted delayed from the center, and the assembly arrangement direction. The ultrasonic convergence effect can be obtained along the line.
[0029]
FIG. 4 shows a configuration example when the principle of the present invention is applied to a 1.5D vibrator.
[0030]
4A is a top view, FIG. 4B is a front view, and FIG. 4C is a side view. In the figure, the X direction is the electronic scanning direction, and the Y direction is the elevation direction. That is, this 1.5D transducer has a configuration in which a plurality of one-dimensional array transducers are aligned in the elevation direction.
[0031]
In FIG. 4, sound velocity control elements 22 that are two-dimensionally arranged corresponding to the ultrasonic vibration elements 14 arranged in the X direction and the Y direction are provided. In order to realize electronic scanning, each ultrasonic vibration element 14 is electrically and acoustically separated in the X direction. On the other hand, to realize focusing in the elevation direction, the ultrasonic vibration element 14 is in the Y direction. The sound velocity control elements 22 are acoustically and electrically separated along the Y direction. That is, the signal side electrode 16 is provided for each column along the Y direction, and the control side lead 24 is provided for each column along the X direction. The ground-side lead 18 is provided in common for all elements.
[0032]
Therefore, in the above configuration, when electronic scanning is performed in the X direction, the ultrasonic beam can be focused along the elevation direction by weighting the Y direction by controlling the sound velocity. Of course, a known acoustic lens can also focus an ultrasonic beam in the elevation direction, but according to the sound speed control according to the present invention, there is an advantage that the focus point can be freely changed.
[0033]
Incidentally, in the configuration shown in FIG. 4, an acoustic lens is used as necessary. When an acoustic lens is used, the sound speed of each sound speed control element 22 is controlled in consideration of the sound convergence effect.
[0034]
FIG. 5 shows a configuration example when the principle of the present invention is applied to a 2D vibrator. The piezoelectric vibration elements 14 are two-dimensionally arranged, while the sound speed control elements 22 are also two-dimensionally arranged. The signal side electrode 16 is provided for each Y column along the Y direction, and the control side lead 24 is provided for each X column along the X direction. That is, in the X direction, the first electronic scanning by the electronic delay control is realized as in the conventional case, and in the Y direction, the second electronic scanning by the sound speed control is realized. According to such a configuration, there is an advantage that the total number of signal lines can be greatly reduced as compared with the conventional case where signal lines are connected to each vibrator and individually controlled. In FIG. 5, the ground-side lead 18 constitutes a common electrode for each element.
[0035]
If the vibrator shown in FIG. 5 is used, it is possible to construct an ultrasonic diagnostic apparatus that can be obtained at low cost and obtain high image quality, and it is possible to realize a vibrator that is particularly useful for three-dimensional image formation.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a new beam forming method that changes to signal delay control, and in particular, to realize a 1.5D vibrator or a 2D vibrator with a reduced number of signal lines. it can.
[Brief description of the drawings]
FIG. 1 is a principle explanatory diagram for explaining the principle of the present invention;
2 is a circuit diagram showing an example of an impedance control unit 30. FIG.
FIG. 3 is a diagram illustrating a configuration example of an impedance control unit 30 in the ultrasonic diagnostic apparatus.
FIG. 4 is a diagram showing an example in which the present invention is applied to a 1.5D vibrator.
FIG. 5 is a diagram illustrating an example when the present invention is applied to a 2D vibrator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Ultrasonic probe, 12 Apparatus main body, 14 Piezoelectric vibration element, 16 Signal side electrode, 18 Ground side lead, 20 Backing, 22 Sound speed control element, 24 Control side lead, 30 Impedance control part, 32 Impedance circuit.

Claims (2)

A group of ultrasonic vibration elements composed of a plurality of ultrasonic vibration elements arranged two-dimensionally;
A plurality of sound speed control elements provided for each of the ultrasonic vibration elements, and having a function of adjusting the sound speed of the passing ultrasonic waves;
Electronic control means for performing electronic scanning or electronic focusing in the x direction for each y direction row aligned in the y direction among the plurality of ultrasonic transducer elements;
The speed of sound for performing focus or beam angle scanning by controlling the sound speed of the sound speed control element array corresponding to the x direction row for each of the x direction rows aligned in the x direction among the plurality of ultrasonic vibration elements. Control means;
An ultrasonic diagnostic apparatus comprising: A group of ultrasonic vibration elements composed of a plurality of ultrasonic vibration elements arranged two-dimensionally;
A plurality of sound speed control elements provided for each of the ultrasonic vibration elements, and having a function of adjusting the sound speed of the passing ultrasonic waves;
Electronic delay control means for performing angular scanning or focusing of the beam in the x direction by electronic delay control in the x direction for each y direction row aligned in the y direction among the plurality of sound velocity control elements. ,
For each of the plurality of ultrasonic vibration elements arranged in the x direction along the x direction, the sound speed of the sound speed control element array corresponding to the x direction row is controlled to perform focus in the y direction or beam angle scanning. Sound speed control means to be executed;
An ultrasonic diagnostic apparatus comprising:

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