JPH0649287Y2 - Ultrasonic diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides an ultrasonic wave in which focusing is performed by an electronic focusing method by giving a predetermined delay amount to each of a plurality of ultrasonic wave vibrators that constitute a probe. The present invention relates to a diagnostic device, and more particularly to a probe portion of a linear scanning type or a convex scanning type.

[Conventional technology]

When scanning a beam in an ultrasonic diagnostic apparatus, an electronic scanning method is generally used. In this electronic scanning system,
A probe is composed of multiple micro-vibrators,
By controlling the driving timing of each transducer, the ultrasonic beam is electronically scanned.

In such an electronic scanning method, so-called electronic focusing that narrows the beam at an arbitrary position is possible. This electronic focus method, for example, receives the ultrasonic waves reflected from the focal point in the living body by each micro-vibrator and gives an appropriate delay time to each of the signals obtained by these micro-vibrators, This is to add the signals by aligning the phases of the signals from the focus. The focus setting when transmitting is the same,
By giving a delay time similar to that of receiving waves to the focus for each micro-vibrator, the transmitted ultrasonic beam is focused at a predetermined focus point.

By the way, in a probe having a plurality of minute oscillators arranged in an array as described above, the occurrence of grating lobes becomes a problem. This grating lobe is generated in a direction different from the direction of the main beam, which causes the generation of a virtual image in ultrasonic diagnosis and causes a misdiagnosis.

[Problems to be solved by the device]

It is known that the grating lobe as described above affects the distance between adjacent oscillators. That is, the grating lobe can be eliminated by making the transducer interval smaller than the wavelength of the ultrasonic beam. However, if the distance between the transducers is reduced, the field of view becomes narrower. Further, in order to widen the visual field width while keeping the transducer interval small, it is necessary to increase the number of channels. However, if the number of channels is increased, the number of circuits for driving the transducers increases and the cost increases.

Further, even if the vibrator interval is made small enough to prevent the generation of the grating lobe, when electronic focusing is performed, a phase gap due to the delay time is generated between the adjacent vibrators, and the grating lobe is generated.

An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of obtaining a good image with an inexpensive structure.

[Means for Solving the Problems]

An ultrasonic diagnostic apparatus according to a first aspect of the present invention, which has been made to solve the above problem, provides a predetermined delay amount to each of a plurality of ultrasonic transducers forming a probe, and performs focusing by an electronic focusing method. In the ultrasonic diagnostic apparatus described above, each of the ultrasonic transducers is formed by being separated into a plurality of elements, and each element is joined by a filler having an acoustic impedance close to the acoustic impedance of the element, and adjacent vibrations are formed. By connecting the elements with a filler having an acoustic impedance close to the acoustic impedance of the element, adjacent transducers are acoustically coupled and vibrate in substantially the same phase, and the directional characteristics of each ultrasonic transducer are narrow. Therefore, the gain in the grating lobe direction is reduced.

In addition, an ultrasonic diagnostic apparatus according to a second aspect of the present invention, which has been made to solve this problem, gives a predetermined delay amount to each of a plurality of ultrasonic transducers that form a probe, and performs focusing by an electronic focusing method. In the ultrasonic diagnostic apparatus thus configured, each of the ultrasonic transducers is formed by being separated into a plurality of elements, and the elements are electrically connected to each other through impedance, and the impedance between adjacent transducers is reduced. By connecting via, the adjacent transducers are electrically coupled and oscillate in almost the same phase,
By narrowing the directional characteristics of each ultrasonic transducer,
The feature is that the gain in the grating lobe direction is reduced.

[Action]

In the present invention, by driving the oscillators by acoustically or electrically coupling the adjacent oscillators, the adjacent oscillators are affected by each other and vibrate in the same phase. Has increased.

Generally, as the property of ultrasonic waves, the gain in the main lobe direction (vertical direction to the vibrating surface of the vibrator) hardly changes as the width of the transducer increases, but the gain sharply decreases as the angle deviates from the main lobe direction. The directivity tends to be narrow. Therefore, when the effective oscillator width increases due to acoustic or electrical coupling with the adjacent oscillator, the gain in the main lobe direction hardly changes, and the other angular directions (including the angular direction in which the grating lobe occurs). The gain of is greatly deteriorated.

That is, it is possible to narrow the directivity and deteriorate the gain in the angular direction other than the main lobe direction by acoustically or electrically coupling the adjacent vibrators to increase the width of the vibrator that vibrates in the same phase. it can.

On the other hand, in a probe having a plurality of minute oscillators arranged in an array like this configuration, a grating lobe occurs due to the periodical arrangement of the oscillators. This grating lobe depends on the spacing between adjacent oscillators. The angle direction in which the lobes are generated is determined, and this angle direction does not change depending on the magnitude of acoustic coupling or electrical coupling between the adjacent transducers.

Here, since the angle direction in which the grating lobe is generated is a direction away from the main lobe direction by a predetermined angle (determined by the distance between the transducers), the direction other than the main lobe direction is determined by the acoustic or electrical coupling. If the gain is deteriorated, the gain in the grating direction is also deteriorated, so that the grating lobe can be suppressed low.

〔Example〕

First, the overall configuration of the ultrasonic diagnostic apparatus will be described with reference to FIG. The transmission system of this device is composed of a transmission pulse generation circuit 1, a transmission side delay control circuit 2 and a high voltage pulse generation circuit 3. The transmission pulse generation circuit 1 is a circuit that generates a transmission pulse in response to a control signal from the control circuit 10. The transmission-side delay control circuit 2 is composed of a delay line with taps, a multiplexer, and the like, and gives a delay time to the transmission pulse from the transmission pulse generation circuit 1 to perform electronic focusing. The high-voltage pulse generation circuit 3 is a power amplifier circuit, which amplifies a transmission pulse given a predetermined delay amount and generates a high-voltage pulse for driving the vibrator.

As shown in FIG. 2, the probe 4 comprises an electronic changeover switch 11 and a transducer group 12 which is switched and driven by the electronic changeover switch 11. Details of the vibrator group 12 will be described later.

The reception system includes an amplification circuit 5 that receives and amplifies the reflection echo received by the probe 4, and a reception-side delay control circuit 6
And an image processing circuit 7. The reception-side delay control circuit 6 is similar to the transmission-side delay control circuit 2 and includes a delay line with taps for electronic focusing, a multiplexer, and the like. The image processing circuit 7 is composed of a detection circuit and the like, and performs signal processing on the reflected echo.

The output of the image processing circuit 7 is connected to a digital scan converter (hereinafter referred to as DSC) 8. DSC
Reference numeral 8 has an A / D converter and a D / A converter, a frame memory, an address generation circuit for generating each address for writing and reading, and the output thereof is displayed on the monitor 9.

As shown in FIG. 2, a convex scanning type probe is used as the probe 4 in this embodiment, and the vibrator portion thereof is shown in an enlarged scale in FIG. Each of the vibrators 13 and 14 is subdiced into three elements. That is, the vibrator 13 is composed of elements 13a, 13b, 13c,
The vibrator 14 is composed of elements 14a, 14b and 14c. Incidentally, each of the sub-diced elements 13a, 13b,
13c and 14a, 14b, 14c are electrically connected to each other, and continuous, for example, 32 vibrators such as the vibrators 13 and 14 are driven at substantially the same timing.

The vibrators and elements divided as described above are joined to each other by the filler 17. The filler 17 is conventionally made of epoxy resin or the like, and has a sufficiently low acoustic impedance as compared with that of the vibrator in order to generate impulse ultrasonic pulses. However, in this embodiment, in order to give a proper coupling between the adjacent oscillators, for example, "epoxy 2850FT-FRJ" is used as the filling material 17, and the acoustic impedance is set to that of the oscillator as compared with the conventional one. Approaching. As a result, the width of the distortion of the sound emitted from one oscillator becomes equal to or greater than the width of that oscillator, and the same action as when a virtually wide oscillator is driven compared to the case where there is no acoustic coupling. Is obtained. The tip side of the vibrator group 12 (first
An acoustic matching layer 16 is provided on the lower side of FIGS. And 2) for acoustic matching with a living body, and a backing member 15 is provided on the opposite side.

Next, the operation will be described.

The operation of the entire apparatus is exactly the same as that of the conventional apparatus. That is, when the control signal is sent from the control circuit 10 to the transmission pulse generation circuit 1, the transmission pulse generation circuit 1 outputs a trigger pulse. This trigger pulse undergoes a predetermined delay in the transmission side delay control circuit 2, and the high voltage pulse generation circuit 3
Entered in. The tap of the delay line of the transmission side delay control circuit 2 is switched by the signal from the control circuit 10. In the high voltage pulse generation circuit 3, the delayed trigger pulse is amplified and a pulse for driving the vibrator is output. This high voltage pulse is applied to each of the oscillators 13 and 14 of the probe 4 via the electronic changeover switch 11, whereby the ultrasonic beam is transmitted in a predetermined direction.

Further, the electronic changeover switch 11 of the probe 4 is changed over and controlled by a control signal from the control circuit 10, whereby the ultrasonic beam B is scanned in the direction indicated by the arrow P, as shown in FIG.

The reflected echo of the ultrasonic beam from the living body is input to the amplification circuit 5 and is amplified therein. After that, the reception-side delay control circuit 6 receives a predetermined delay amount similar to that at the time of transmission, electronically focuses it and sends it to the image processing circuit 7. Then, the image processing circuit 7 undergoes detection processing or the like to obtain tomographic image data. This tomographic image data is input to the DSC 8 where it is converted into a television signal. The data converted into the television signal is displayed on the monitor 9.

At this time, as the filling material 17 between each vibrator and element, one having an impedance close to the acoustic impedance of the vibrator is used as compared with the conventional one, so that the adjacent vibrators are acoustically appropriately coupled. It Therefore, the adjacent transducers will affect each other and will vibrate in the same phase, increasing the effective transducer width.
The directional characteristic of each transducer becomes narrow. On the other hand, the angular direction in which the grating lobes are generated is determined by the distance between the oscillators, and the angular direction does not change due to acoustic or electrical coupling.

This state is schematically shown in FIG. 3, the curve D ₀ shown by the chain double-dashed line in the figure is the directivity characteristic of the conventional probe, and the curve D ₁ shown by the solid line is the directivity characteristic of this embodiment. As is clear from this figure, even if the directivity is narrowed, the gain does not deteriorate in the main beam M direction, but the gain deterioration in the focus direction F is L _F , and the deterioration in the grating lobe direction G is L _G. As shown, it deteriorates significantly.

As described above, in the present embodiment, the directional characteristics of each oscillator are narrowed by acoustically coupling the adjacent oscillators and providing an appropriate coupling, and the deterioration of the gain in the direction in which the grating lobe occurs is reduced. It will be noticeable. Therefore,
The grating lobe can be kept low.

As a result, the grating lobes can be kept low without changing the pitch of the transducers to the pitch of the conventional device, that is, with a large diameter, and without increasing the number of transmitting / receiving circuits, and good image quality can be obtained at low cost. To be

[Other Examples]

(A) In the above embodiment, the vibrators are acoustically coupled by the filler, but the vibrators may be electrically coupled.

FIG. 5 shows an embodiment in which the respective vibrators are electrically coupled.
5, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. Similar to the above embodiment, each of the vibrators 13 and 14 is sub-diced and divided into three elements.
The elements 13a, 13b, 13c of this one group are connected to the transmission / reception circuit 20a via the impedance Z ₀ 22. The transmission / reception circuit 22a corresponds to the transmission system and the reception system in FIG. Similarly, each element 14 of the adjacent transducer 14
a, 14b, 14c are connected to the transmission / reception circuit 20b via the impedance Z ₀ 22.
It is connected to the. Also, between the elements of each transducer,
Impedance Z23 is connected. In this way, the impedances Z and Z _{0 form} a circuit network having a periodicity with each sub-diced oscillator as a unit. The impedances Z and Z ₀ are composed of a coil, a capacitor, a resistor and the like.

In this way, the impedance Z
By electrically coupling with each other, the directivity of each vibrator is narrowed as in the above-described embodiment. As a result, as shown in FIG. 3, the gain in the grating lobe direction becomes low, and the grating lobe can be suppressed low.

(B) In each of the above-mentioned embodiments, the probe of the convex type is shown, but the probe can be similarly applied to the linear scanning type.

[Effect of device]

As described above, according to the present invention, since the adjacent transducers are acoustically or electrically coupled to each other so that the directional characteristic of each transducer is narrowed, the grating lobe can be suppressed low without reducing the pitch between the transducers. It is possible to obtain a good image with an inexpensive structure.

[Brief description of drawings]

FIG. 1 is a diagram showing a probe structure applied to an ultrasonic diagnostic apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the entire structure thereof, FIG. 3 is a diagram showing the effect of the probe, FIG. 4 is an overall block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 5 is a diagram showing another embodiment of the present invention. 4 ... Probe, 13, 14 ... Transducer, 17 ... Filling material, 22,
23 ... Impedance.

Claims (2)

[Scope of utility model registration request] 1. An ultrasonic diagnostic apparatus in which focusing is performed by an electronic focusing method by giving a predetermined delay amount to each of a plurality of ultrasonic transducers constituting a probe, wherein each ultrasonic transducer is composed of a plurality of ultrasonic transducers. Separately formed into elements, each element is joined with a filler having an acoustic impedance close to that of the element, and adjacent transducers are filled with a filler having an acoustic impedance close to that of the element. By joining, the adjacent transducers are acoustically coupled and vibrate in almost the same phase, and the directional characteristics of each ultrasonic transducer are narrowed, and the gain in the grating lobe direction is reduced. And ultrasonic diagnostic equipment. 2. An ultrasonic diagnostic apparatus in which focusing is performed by an electronic focusing method by giving a predetermined delay amount to each of a plurality of ultrasonic transducers that constitute a probe, wherein each ultrasonic transducer includes a plurality of ultrasonic transducers. Separately formed into elements, each element is electrically connected via impedance, and adjacent transducers are connected via impedance to electrically couple adjacent transducers. The ultrasonic diagnostic apparatus is characterized in that the gain in the grating lobe direction is reduced by causing the ultrasonic transducers to oscillate in substantially the same phase and narrowing the directional characteristics of the ultrasonic transducers.