JPS63153054A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The present invention is an ultrasonic diagnostic apparatus that receives ultrasonic waves using a plurality of arranged transducers. It is related to. In order to match the phase of the electrical signal from each vibrator at the summing point, the amount of delay t, 1 of the delay circuit provided in the signal path between each vibrator and the summing point is determined according to the measurement depth.
This system receives all of the reflected ultrasonic waves on the scanning line and focuses them over the entire area on the scanning line by changing the received ultrasonic waves.

[Industrial application field]

Ultrasonic diagnostic equipment for the purpose of obtaining tomographic images of the human body generally has inferior resolution compared to other X-ray images, and it is desired to improve the resolution. What is needed is a method that focuses on the entire depth region to be measured, rather than focusing on the entire depth region to be measured.

[Conventional technology]

A conventional dynamic focus method is shown in FIG.

The distances between the measurement point P and each of the arranged transducers 4 (Tl to TN) are different. Therefore, as shown in FIG. 8, the reflected wave from Pl reaches the center vibrator earliest, and the vibrators near both ends receive the wave at a later timing. Therefore, the phase of the signal output from each vibrator will also shift for each element, and even if you add the output signals from each vibrator as is, it will not be n times the individual signal, and worse, they will cancel each other out. On the other hand, the added signal may become smaller. Therefore, the output signal from the central transducer, which receives the wave earlier, is delayed by a large amount, and the delay circuit 1 (DI-DN) is installed as shown in Fig. 9 so that the phase of the output signal from each transducer matches at the addition point. , and delay adder circuit 2 (FD)
The amount of delay can be selected using . 3 is an amplifier (A
t - A N ), the output of each vibrator is amplified to some extent and input to the delay circuit. The delay circuit is composed of a delay line 1 that can set the amount of delay finely and a delay adder circuit 2 that can set the amount of delay coarsely, and the optimum amount of delay can be selected by a combination of the two. Delay addition circuit 2
is as shown in Figure 11 < N1fs21 (dt~dM-x)
are connected in series, and the current signals from each of the delay circuits 1 (DI-DN), ~IN, are respectively connected to switches S1-
1-8 t-my -=8*-t~Sx-MK is selected and input to any tap of the delay line, each delayed by an amount determined by the selected tap, and added to the addition point A (output (common with the terminal) and are added in the same phase. Ro is the terminating resistance of the delay line. The details of the delay circuit 1 (DI-DN) are shown in Figure 10, and its operation is almost the same as that of the delay adder circuit 2 (FD).It is a voltage-current converter that converts a voltage signal into a current signal at the output terminal. VI is connected.

In FIG. 9, first, the ultrasonic wave reflected from the focal point P is received by an array of transducers 4 ('rt = TN) and converted into electrical signals, and these electrical signal waveforms are sent to the delay adder circuit 2. Delay line 1 (
The amount of delay in the D1 to DNL delay addition circuit 2 is set by a switch, and the delay is set at 1 during the period in which ultrasonic waves are received from points at different depths (for example, pt) on the same scanning line.
(Dt-I)N), the delay amount is changed to achieve focusing.

However, immediately after all ultrasonic pulses are emitted from the transducer 4 (T+ -TN) into the body, reflection occurs continuously from a shallow point in the body to a point deeper within the body, and the transducer receives a continuous reflected wave. will arrive. Therefore, in order to focus at each point on the scanning line, the delay amount of the delay circuit 1 (Dt to DN) is changed at the same time while receiving the reflected wave from the scanning line.

Kutuokasu was all there.

[Purpose of the invention]

In the conventional method, as shown in Fig. 10, the amount of delay is changed by switching the path through which the signal is transmitted, so the signal may be cut off when the switch is changed, or the switch switching control signal may be induced and mixed into the signal as noise. The image was distorted.

[Structure of the invention]

FIG. 1 shows a diagram of the principle of dynamic focus according to the present invention. In the figure, 4 (T1 to TN) is an arrayed vibration vibrator, 3 (A
1 to AN) are amplifiers, 10 (PSt to psN) is a phase shift circuit, and 2 is a delay addition circuit.

The present invention utilizes the delay line in FIG. 9 of the conventional system, ~DNt-
It is replaced with phase shift circuits PSt to PSN.

As shown in FIG. 2, the phase shift circuit is composed of a delay circuit 11 (D) that delays approximately 1/4 of the period of the input signal, a multiplier MU, and an adder circuit ADD. (MU+, MU Rini CO)
It has a function of changing the phase of the input signal VcosWt by θ by inputting a value of Wθ, -5inθ. Delay circuits D1 to D in FIG. 9 of the conventional system
The amount of delay required to focus the signal at N is τN
If the angular frequency of the received ultrasonic wave is W radian/second, the relationship θN=wτN holds true between the phase shift amount θN in the phase shift circuit of the present invention, and the conventional method Instead of delaying τN, WfN radians may be set as θ in FIG.

Vcos W (t-14th 2r/W) = Vcom (Wt
−M/2)=Vsln wt Vcos wt cosθ+Vsin wt ainθ
= Vcg6 (vt - θ) It is possible to set θ to 2π radians as the value of θ, and it is possible to shift the phase by one wavelength, so no matter how much the two waves are out of alignment, they are aligned. Limit #) It has the feature that it is possible to match the phases of two waves. FIG. 3 shows how the phase of the output waveform changes with respect to the value of θ. In addition, in this method, if the phase change required depending on the measurement depth is θ(1), eolIθ is input to one of the inputs of each of the two multipliers.
(1) and sinθ(t), which only needs to be input as analog signals that change slowly over time, has the advantage that there is no noise caused by switching, etc., as in conventional methods. .

[Embodiments of the invention]

FIG. 4 shows an embodiment of the present invention.

4 (T1~TN) are arranged vibrators, 3 (81~AM
) is an amplifier, 10 (PS, ~PSN) is a phase shift circuit, and 13 (PSC) is a phase shift circuit f! :#J control phase control circuit, 14 (TM) is a transmitting circuit, and 2 (FD) is a delay addition circuit. l5 (DLC) is delay addition circuit 2O
j! This is a delay amount control circuit that changes the amount of delay. First, in a state where no phase shift occurs in the first phase shift circuit 10 (PSI to PSN), each transducer 4 (Tl to T) J receives a reflected wave from a point at a certain depth, for example, 21 points in FIG. ) in the delay adder circuit 2 so that the phase of the electrical signal generated from the adder circuit 2 best matches the phase of the electrical signal at the adder point A of the delay adder circuit 2 (which is shared with the output terminal in this case). Set the extension amount. Details of the delay adder circuit 2 are shown in FIG. Specifically, the output of each phase shift circuit is inputted from the corresponding input terminal of the delay adder circuit, and the switches 51-1 to S1-Me...
..., 5M-1 to SN-M From K, a delay line d of about one period of ultrasonic waves.

~dM-1 connected in series, any one of the delay lines,
The amount of delay within the delay and addition circuit is set by selecting the phase adjustment circuit so that the phases of the electrical signals best match each other at the addition point.

In this way, after setting the amount of delay in the delay adder circuit,
Furthermore, in order to ideally match the phases at the addition points, the phases of the electrical signals from the corresponding vibrators are shifted by an appropriate amount from the phase shift circuits 10 (PS> to P!l5) VC. FIG. 5 shows details of one of the phase shift circuits 10 (PS, -PSN). In the figure, MEI, MEt are storage circuits, DAt, DAt are DA converters, MUs,
MUt is a multiplier, SHl and SHl are sample and hold circuits, D is a delay circuit with a delay i- of about 1/4 of the ultrasonic period received by the transducer, ADD is an adder circuit, vI is a voltage signal and a current signal This is a voltage-current conversion circuit that converts into

The input signal Vt input from the input terminal is directly input to the multiplier MU and Ic, and the multiplier MUtK is input via the delay circuit Dt-. The amount of phase shift θ to be corrected changes in accordance with the depth of the measurement point, so it can be expressed as a function of time. If this is θ(1), then the values of eoIlθ(1) and -5inθ(1) are sampled at certain time intervals and stored in the memory circuits ME, , ME, respectively, read out at times corresponding to the measured depths, and then sent to the respective DA converters DA, DA! The sample and hold circuits SHI and SAT hold the output signals until the next information is read out from the memory circuit, and at the same time, the respective outputs t' MUt
Enter 9MUt. MU obtained in this way,
, MUt's output signals are added by the adder ADD, the phase of the input signal Vt is shifted by θ(1),
Appears as a voltage signal at the output of ADD. This voltage signal is converted into a t optical signal by a voltage-current converter and sent to the next delay addition circuit.

In this way it is possible to focus on all measurement points.

In the embodiment of FIG. 5, the delay time of the delay circuit is set to 1/4 of the period of the input signal, but it may not be 1/4 of the period. It is also possible to omit the sample holds SHt, SH, and C. Also, although the embodiment shown in Fig. 5 uses t-2 multipliers, it is also possible to configure it with three or more multipliers as shown in Fig. 7, and the delay amount of the delay circuit at this time can also be input. It is also possible to take a value other than 1/4 of the period of the signal.

Various other shapes can be considered, but the basic idea of the present invention is to generate one or more signals delayed from the input signal from the delay circuit button without generating noise, and to calculate the coefficients of each of these signals. Rather than multiplying by In Figure 5, e08θ(1) and @lnθ(1)
t-multiplied by a constant, respectively, kcosθ(1) and k
Of course, it is also possible to multiply by min θ (1). However, k is a constant.

〔Effect of the invention〕

According to the present invention, the ideal phase correction can be made without generating any noise, and because the phase can be corrected continuously instead of changing the phase in steps or steps like a delay line. It can be easily realized by fk@path.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining the present invention in detail. 4 (T1 to TN) is a resonator, 3 (A, to AN) is an amplifier, 10 (PSs to PSN) is a phase shift circuit, 2 is a delay addition circuit, 12 (MUl, MU snow) is a multiplier, 11
is a delay circuit. FIG. 4 to FIG. 7 are illustrations of embodiments. 10 (PSt=PSN) is a phase shift circuit, 1a (PSt=PSN)
C) is a phase control circuit, 15 (DI, C) is a delay amount control circuit, and 14 (TM) is a timing control circuit MEt, M
E Snow is...) Memory circuit, NDAs, DA@ is DA converter, SHl,
SHL is a sample and hold circuit. 8 to 11 are conventional configuration diagrams. D1~DN are delay circuits, 81~SN are switches, 41~
6w-t is a delay line, and v-connector is a voltage-current converter. 〒 (■ 15i) 1L9 za 2 roki 3 呵 4 岑 5 Mouth trouble 6 drunkenness 11 Oral procedure amendment (voluntary)

Claims (3)

[Claims] (1) In an ultrasonic diagnostic device that uses a plurality of ultrasonic transducers to electronically scan an ultrasonic beam, the ultrasonic transducers have a function of converting between sonic energy and electrical energy; An ultrasonic diagnostic apparatus comprising: a phase shift circuit connected to a vibrator; and a phase control circuit that controls the phase of the phase shift circuit according to a measurement depth. (2) Claim (1) characterized in that the phase shift circuit is composed of a delay circuit, a multiplier, and an addition circuit.
) The ultrasonic diagnostic device described in item 2. (3) the phase shift circuit inputs the input signal to one multiplier via a delay circuit having a delay time of about 1/4 of the period of the received ultrasound, and directly inputs it to the other multiplier; Multiply each input signal by a value set in advance for each multiplier,
The ultrasonic diagnostic apparatus according to claim 1, wherein the phase shift is performed by adding the output signals of the respective multipliers.