JPH031010B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ultrasonic diagnostic apparatus, and particularly relates to a linear electronic scanning ultrasonic diagnostic apparatus that scans an ultrasonic beam by switching a plurality of transducers. .

[Technical background of the invention and its problems]

Linear electronic scanning ultrasound diagnostic equipment uses a scanning method (hereinafter also referred to as linear electronic scan) in which a large number of transducers are arranged and the center position of the ultrasound beam is electronically moved by switching the transducers one by one. This is what I did. In such a linear electronic scan, various driving methods have been proposed in which beam scanning is performed at intervals narrower than the pitch intervals of the transducers in order to improve the resolution of the ultrasonic image.

For example, the one shown in Fig.
-73587), first, five transducers T ₁ to _{T 5} are simultaneously driven by pulsers P ₁ to _{P 5} to generate an ultrasonic beam having the center at position B ₁ , and then six transducers By driving the transducers T ₁ to _{T 6} simultaneously by the pulsers P ₁ to _{P 6} , an ultrasonic beam having the center at the B ₂ position is generated, and then the transducers T ₁ to _{T 6} , T ₂ to _{T 7} , T ₂
The purpose is achieved by sequentially driving a combination of .about.T ₇ , . In this way, the number of vibrators and the circuits connected thereto can be reduced, and an image with high scanning line density can be obtained. However, since the number of transducers to be driven simultaneously increases and decreases alternately, the output of the emitted ultrasonic waves differs alternately, resulting in a difference in the intensity of the reflected waves and the problem that a striped pattern appears in the image. arise. In this case, a method is adopted in which the gain of the amplifier is adjusted by alternately increasing and decreasing it, but the circuit configuration becomes complicated and the S/N ratio does not change depending on the gain, so it is still possible to adjust the gain by increasing or decreasing the gain of the amplifier. This will result in a pattern.

In addition, a method has been proposed in which the number of driving transducers during transmission and the number of driving transducers during reception are different, thereby scanning an ultrasound beam at an interval of 1/4 of the transducer pitch. However, because the number of transducers used during transmission and reception differed, the energy of each ultrasonic wave changed, resulting in the same striped pattern as described above.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and is a linear electronic scanning system that moves the center of an ultrasonic beam at intervals finer than the transducer pitch and can equalize the ultrasonic energy transmitted and received each time. The object of the present invention is to provide a shaped ultrasonic diagnostic device.

[Summary of the invention]

To achieve the above object, the present invention performs ultrasonic scanning by sequentially shifting the position of each group of transducers including n transducers smaller than the total number of transducers in a plurality of transducers arranged and driving them simultaneously. The device is characterized by a combination of simultaneous driving of n adjacent vibrators and simultaneous driving of n+a vibrators excluding a vibrator located in the center part. It is something to do.

[Embodiments of the invention]

The present invention will be specifically explained below with reference to the drawings.

FIG. 2 is a diagram explaining the principle of the present invention. As shown in the figure, first, when six transducers T ₁ to _{T 6} are driven simultaneously, the center position of the ultrasonic beam becomes position B ₂ (a), and then T ₁ except T ₄ 6 up to T ₇
When two transducers are driven simultaneously, the center position of the ultrasonic beam becomes position B ₃ (simultaneous b), and similarly, T ₂
When six transducers up to T ₇ are driven simultaneously, the center position of the ultrasonic beam becomes B ₄ (c in the same figure), and then T ₅
When six transducers from T ₂ to _{T 8} excluding T 8 are simultaneously driven, the center position of the ultrasonic beam becomes the position B ₅ .

In this way, beam scanning can be performed at intervals of 1/2 of the transducer pitch, and since the number of simultaneously driven transducers is always the same, the ultrasonic energy emitted each time can be made uniform.

Although the above explanation has been about the driving method when transmitting ultrasonic waves, it goes without saying that the same applies to the case of receiving ultrasonic waves.

FIG _. 3 shows the configuration of an embodiment of the present invention in which a phase control function for electronic focus is added for transmission and _reception . 8 groups 31,3
2,...,38, and each of these groups 3
Transducers located at the same position among 1 to 38, that is, T ₁ to _{T 9} located first from the end in each group,...
_Eight variable delay lines D1 to _D8 are provided which commonly correspond to _T57 , second position _T2 , _T10 ..., _T58 , eighth position _T8 , _T64 , respectively. and,
These variable delay lines D ₁ to _{D 8} control the drive timing of each pulser that supplies pulses to the corresponding transducer (the timing of the clock pulse supplied to each pulser) and the ultrasonic pulse received by the corresponding transducer. It is designed to delay analog electrical signals. Note that A ₁ to A ₈ are amplifiers that amplify the received ultrasonic pulses extracted by the switching circuit, Wi ₁ to Wi ₈ , Wo ₁ to _{Wo 8} are variable delay lines D ₁ to _{D 8}
In order to share the information when sending and receiving, the input,
This is a switch that switches the output side. Also, S ₁ ~ _{S 64}
is a switching circuit, G ₁ G ₆₄ is a NAND gate circuit, L ₁ to _{L 64} are limiters, and P ₁ to P ₆₄ are pulsers. 11 is a clock pulse generator; 13 is a clock pulse generator;
is a high frequency amplifier.

Next, the operation of this device will be explained. First, when the first clock pulse is output from the clock pulse generator 11, the clock pulse is sent to the switch _Wi1.
~ Solid line side of Wi ₈ , variable delay line D ₁ ~ D ₈ , switch Wo ₁
The solid line side of ~ _Wo6 is supplied to the pulsers _P1 to _P6 via the NAND gates _G1 to G6, and the pulsers _{P1 to P6 are} driven. At this time, each delay time _t1 to _t8 of _the variable delay lines _D1 to D8 is expressed as _t1 = _t6 , _t2 = _t5 , _t3 = _t4 , _t1 < _t2 <
If controlled to an appropriate value of t ₃ , the ultrasonic beam will be focused at the desired position. At this time, only S ₁ to _{S 6} of the switching circuit are on, and only the reflected ultrasonic pulses received by the transducers T ₁ to _{T 6} are sent to the limiters L ₁ to _{L 6} and the switching circuits S ₁ to _{S 6} through,
Furthermore, the dotted line side of the amplifiers A ₁ to A ₆ and the switch Wi ₁ to _{Wi 6} ,
They are summed via variable delay lines D ₁ to _{D 6} (t ₁ to _{t 6} are set the same as during transmission), and as a result, the reflected ultrasound pulses from the desired position are transmitted to the high frequency amplifier in an emphasized manner. 13. At this time, the center position of the ultrasonic beam transmission and reception is located between the transducers T ₃ and T ₄ . Next, when the second clock pulse is output, the NAND gate turns on only _G1 to _G7 excluding _G4 , and the switching circuit turns on only _S1 to _S7 excluding _S4 , and _P4 , _T4 , P ₁ ~ _{P 7} except S ₄ , T ₁ ~
T ₇ , S ₁ to S ₇ are activated, but at this time the variable delay line
The relationship between each delay time t ₁ to _{t 7} of D ₁ to _{D 8} is t ₁ = t ₇ , t ₂
= t ₆ , t ₃ = t ₅ , t ₁ < t ₂ < t ₃ . At this time, the center position of the ultrasonic beam becomes the center of the transducer _T4 , and has moved by 1/2 of the transducer pitch. Next, when the third clock pulse is output, the delay line
The pulses passing through D ₃ to D ₇ actuate pulsers P ₂ to _{P 7} to drive oscillators T ₂ to _{T 7} . In the switching circuit, only S ₂ to S ₇ are on, and T ₂ to T ₇
Only the received ultrasonic waves are added through delay circuits D ₂ to _{D 7} and supplied to the high frequency amplifier 13 . The delay times are t ₂ = t ₇ , t ₃ = t ₆ , t ₄ = t ₅ , and t ₂ <t ₃ <t ₄ . At this time, the center position of the ultrasound beam is the transducer
It is halfway between T ₄ and T ₅ , and is shifted by one pitch compared to the first clock pulse. Fourth
In the clock pulse of G ₂ to _{G 8} except G ₅ and S ₅ ,
Activate the NAND gates and switching circuits of S ₂ to S ₈ and set the delay circuits to D ₂ to D ₈ , t ₂ = t ₈ , t ₃ = t ₇ ,
Let t ₄ = t ₆ and t ₂ < t ₃ < t ₄ . In the fifth clock pulse, only G ₃ to _{G 8} and S ₃ to _{S 8} are turned on, and the delay time is t ₃
= t ₈ , t ₄ = t ₇ , t ₅ = t ₆ , t ₃ < t ₄ < t ₅ , in the sixth clock pulse, only G ₃ to G ₉ and S ₃ to S ₉ excluding G ₅ and G ₆ are on, and the delay times are t ₃ = t ₁ , t ₄ = t ₈ , t ₅ =
Let t ₇ and t ₃ < t ₄ < t ₅ . Repeat the same operation sequentially, and the ultrasonic beam will be 1/1/2 in the converged state.
Move 2 pitches at a time.

FIG. 4 is an explanatory diagram of another embodiment of the present invention.
First, T ₁ to T ₆ are used for transmission, and T ₁ to T ₆ are used for reception (see figure a), then T ₁ to _{T 6} are used for transmission, and T ₄ is excluded for reception.
T ₁ to _{T 7} are used (see figure b), and the third one is used for both transmission and reception.
The fourth uses T _{1 to} T ₇ excluding T 4 (c in the same figure), the fourth uses T ₂ to _{T 7} when transmitting, and uses T ₁ to T ₇ excluding T ₄ during reception (d in the same figure), The center position of the ultrasonic beam can be moved at an interval of 1/4 of the transducer pitch by driving in such a way that T ₂ to T ₇ are used for both transmission and reception (see figure e). .

According to the present invention described in detail above, the center position of the ultrasound beam, that is, the scanning line position, can be moved at intervals finer than the pitch of the transducer, and the energy (or power ) is the same each time, so there is no need for amplifier gain correction as in the conventional case, and striped patterns due to essential S/N differences do not occur. Furthermore, since the selection of transducers during transmission and reception is always symmetrical, there is also the advantage that it is convenient for electronic focusing.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional example, Fig. 2 is an explanatory diagram of the principle of the present invention, Fig. 3 is a configuration diagram of one embodiment of the device of the present invention, and Fig. 4 is an explanatory diagram of another embodiment of the present invention. It is. T ₁ to T ₆₄ ……oscillator, P ₁ to _{P 64} …… pulsar,
_A1 to _A6 ...Amplifier, _D1 to _D8 ...Delay line, 31 to
38... Vibrator group.

Claims (1)

[Claims] 1. A device that performs ultrasonic scanning by sequentially shifting the position of each group of transducers including n transducers, which is smaller than the total number of transducers in a plurality of arrayed transducers, and driving them simultaneously. , an ultrasonic wave characterized by combining simultaneous driving of n adjacent transducers and simultaneous driving of n+a transducers excluding a transducer located in the center part. Diagnostic equipment (however, n
>a, a is an integer). 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the number n of transducers in the transducer group is an even number.