JPH01227742A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To converge an ultrasonic beam in best condition by specifying the delay quantity of a wave-receiving signal so that the correlation function of the wave-receiving signal can be made the largest. CONSTITUTION:At a correlation device 17 in a phasing circuit 6', one of the wave-receiving signals inputted from plural oscillator elements 1, 1... through delay circuits 7, respectively, is made into a referring signal, and the operation of the correlation function of the signal and the other wave-receiving signals is executed for a specific period. At a control circuit 18, the output signal from the correlation device 17 is inputted, the delay quantity given to the other wave- receiving signals is obtained so that the correlation function can be made the largest, the signal from the control circuit 18 is inputted to a delay circuit controller 19, and thereby, an optimum delay time is set to the delay circuits 7 by the delay circuit controller device 19.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic apparatus that uses ultrasound to obtain a tomographic image of a diagnostic region of a subject, and particularly relates to a phasing circuit having an autofocus function. The present invention relates to an ultrasonic diagnostic apparatus that can correct delay time 1 so that an ultrasonic beam is converged in the best condition even when the sound velocity distribution is not uniform depending on the position of the diagnostic section of a subject.

[Conventional technology]

Conventional ultrasonic diagnostic equipment includes a probe in which a plurality of transducer elements are arranged and transmits and receives ultrasonic waves, and a transducer that applies a drive pulse for emitting ultrasonic waves by giving a predetermined delay time to each of the transducer elements. A wave pulse generator, a delay circuit that gives a predetermined delay time to the received signal from each transducer element of the probe, and an adder that adds the received signals output from each delay circuit and whose phases are aligned. It consisted of a phasing circuit, a detector for detecting the signal phased by the phasing circuit, and a display device for displaying the output signal from the detector as an image. As shown in FIG. 6, the ultrasound beam electron focusing method used in such ultrasound diagnostic equipment uses transducer elements 1, 1 . . . made of narrow piezoelectric elements. When receiving reflected echoes from a diagnostic site with a probe 2 arranged linearly at equal intervals, it is determined which transducer elements 1, 1, . . . . . , each transducer element 1, 1 . delay line 3 to the electrical signal from
The ultrasonic beam is provided with a delay and the phases are aligned, and an adder 3 adds the signals to give directivity to the ultrasonic beam.

When an ultrasonic diagnostic apparatus using an electron focusing method of ultrasound beams based on this principle is used on an actual living body as a subject, the speed of sound in various tissues within the living body is not uniform, so the probe 2 Each of the transducer elements 1, 1. If only a predetermined delay was given to the received signals from ... as described above, the directivity of the ultrasonic beam could deteriorate. Such deterioration in the directivity of the ultrasonic beam is noticeable when diagnosing a region in a living body where a layer of fat, an abdominal region, etc. are present.

In order to solve such problems, it has conventionally been proposed to appropriately correct the delay given to the received signal between each transducer element 1 of the probe 2 by phase feedback (Japanese). Proceedings of the Ki Society of Ultrasonics in Medicine, Vol. 51, No. 159
Pages 160 to 160 (Published November 1986). The configuration and principle will be explained below with reference to FIG. In the figure, reference numeral 2 indicates a plurality of transducer elements 1, 1 . . . are probes arranged in a row to transmit and receive ultrasonic waves, and reference numeral 5 indicates each transducer element 1, 1 . . . of the probe 2. Channel #1 of the received signal received by... #2.・An amplifier is provided for each of the amplifiers 5 and 5 to amplify the received signal.
．． Each transducer element 1, 1 . This is a phasing circuit that gives a predetermined delay time to the received signals from ・, aligns the phases, adds the signals, and outputs the result. The delay amount of the phasing circuit 6 changes according to a control signal from a control device (not shown). Delay circuits 7, 7 . . . provide a predetermined delay time to the received signals from . ...and each delay circuit 7゜7,...
Adder 8 that adds the phase-aligned received signals output from PL, and P L that compares the phase difference between the two received signals.
L (Phase Locked Loop) 9 +
It consists of 9 +... In addition, the above PLL
9 consists of a phase comparator 10 and a low-pass filter 11, as shown in a partially enlarged view in FIG. Further, in FIG. 7, the detector, display device, transmitting signal system, and overall control device after the phasing circuit 6 are not shown.

The phasing circuit 6 includes a plurality of vibrator elements 1.1.
Using the received signal of one transducer element 1 near the center of the probes 2 arranged in a row as a reference signal, the phases of the received signals of other transducer elements 1 are compared, and the received signals of the other transducer elements 1 are compared in phase. By feeding back the result to the amount of delay given to the received signal from the other transducer elements 1, it is attempted to correct the delay time appropriately. That is, the received signal from the transducer element 1 at the center of the probe 2, that is, the channel #
Using the received signal of No. 3 as a reference signal, the received signals of other transducer elements 1 are phase-compared with the reference signal in the PLL 9, and the delay time of the delay circuit 7 is controlled by the phase difference output of the PLL 9. Which transducer element 1.1. The received signals of... are also transmitted to each delay circuit 7, 7. This is to ensure that the phases are aligned when exiting...

At this time, the probe 2 shown in FIG. 7 is fixed, and the ultrasonic waves are repeatedly transmitted and received while the target located on the focal point F shown in FIG. 6 is also fixed.

The reflected echo from the target is sampled with a range gate Tg of a certain length at every repetition period Tr, and the frequency division ratio N of the PLL 9 can be expressed as in the following equation.

N=Tr/Tg...(1) Here, in general, the response speed (lockup time) of PLL9 is expressed by the following equation (2), so in order to achieve fast phase lock, the loop gain must be increased. It is necessary to increase the frequency division ratio N or decrease the time constant T2.

Here, ωn: loop band φ: gain Kv of phase comparator 10: phase gain T2 of delay circuit 7: time constant of low-pass filter 11. In order to apply the phasing circuit 6 incorporating P'LL9 to the phasing circuit 6, it is required to increase its response speed, but at the same time, it is necessary to ensure a sufficient S/N ratio. However, if the response speed is increased, the noise resistance deteriorates, so the optimal design must be made by comparing the two.

[Problem to be solved by the invention]

However, in the phasing circuit 6 in the conventional ultrasonic diagnostic apparatus as shown in FIG. Since the delay time of circuits 7, 7°, etc. is controlled, the stability of the control system may deteriorate due to various changes in ultrasound propagation conditions depending on the diagnostic part of the subject and the influence of external noise. The automatic focusing function of the ultrasound beam was degraded. Therefore, image quality may deteriorate. Furthermore, when noise resistance is improved to eliminate the influence of noise, the response speed becomes slower. If the response speed becomes slow, the ultrasonic beam must be transmitted and received repeatedly in the same direction, impairing the real-time nature of images.

Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can solve these problems.

[Means to solve the problem]

The above purpose is to provide a probe in which multiple transducer elements are arranged to transmit and receive ultrasonic waves, and a transmission pulse generator that applies a driving pulse for ultrasonic emission by giving a predetermined delay time to each of the transducer elements. a delay circuit that gives a predetermined delay time to the received signal from each transducer element of the probe, and an adder that adds the received signals output from each delay circuit and whose phases are aligned. In an ultrasonic diagnostic apparatus having a phase circuit, a detector for detecting a signal phased by the phasing circuit, and a display device for displaying an output signal from the detector as an image, the phasing circuit comprises: a correlator that uses one of the received signals from a plurality of transducer elements as a reference signal and calculates a correlation function between this signal and other received signals for a specific period; Achieved by an ultrasonic diagnostic apparatus comprising a control circuit that determines the amount of delay given to the received signal, and a delay circuit controller that inputs the signal from this control circuit and sets the optimal delay time for the delay circuit. be done.

[For production]

In an ultrasonic diagnostic apparatus configured in this way, a correlator in a phasing circuit uses one of the received signals inputted from a plurality of transducer elements via a delay circuit as a reference signal, and uses this signal and other received signals as a reference signal. Calculating a correlation function with the wave signal for a specific period, inputting the output signal from the correlator in a control circuit and calculating the amount of delay to be given to other received signals so that the correlation function becomes the thickest, A signal from this control circuit is input to a delay circuit controller, and the delay circuit controller sets an optimal delay time for the delay circuit. Thereby, even if the sound velocity distribution is not uniform depending on the diagnostic site of the subject, the delay time can be corrected so that the ultrasound beam is converged in the best possible condition.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasound diagnostic device is:

This system uses ultrasonic waves to obtain a tomographic image of a diagnostic region of a subject, and as shown in FIG. ...and the phasing circuit 6
', a detector 13, a display device 14, and a control device 15.

The probe 2 transmits and receives ultrasonic waves to and from the diagnostic site of the subject, and includes a plurality of transducer probes 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 . ... are arranged in a -column. The probe 2 has a built-in changeover switch 16 that switches between several groups of transducer elements involved in transmitting and receiving ultrasonic waves one by one under the control of a control device 15 in order to perform electronic linear scanning. In FIG. 1, five transducer element groups are sequentially selected, and amplifiers 5, 5, .・It is designed to be connected to. The transmission pulse generator 12 connects each transducer element 1, 1 . A driving pulse for ultrasonic beam emission is applied by giving a predetermined delay time to ..., and the directivity and convergence point of the ultrasonic beam can be arbitrarily controlled by the control device 15. Amplifier 5, 5.・・・
is for amplifying the reflected echo signal received by the manually operated probe 2 via the changeover switch 16, and channel #1 of the received signal received by each transducer element 1, 1°. #
2°...provided in parallel every #5. Phaser circuit 6
' is the amplifier 5, 5 . Each transducer element 1, 1 . A delay circuit 7 is applied to the received signal from...
7. . . give a predetermined delay time to align the phases, and the adder 8 adds and outputs the added signals to give directivity to the ultrasonic beam. The delay circuit 7 is composed of a tapped delay line and an analog switch connected to the tap, and the analog switch is switched by a control signal from the control device 15 to vary the delay time. ing. The detector 13 is provided on the output side of the phasing circuit 6', and detects the signal after logarithmically compressing the signal phased by the phasing circuit 6'. Display device 14
The device receives the output signal from the detector 13 and displays it as an image, and is composed of, for example, a digital scan converter made of a semiconductor memory and a standard scanning television monitor. Note that the control device 15 controls the operation of each of the above-mentioned components.

Here, in the present invention, the phasing circuit 6'
As shown in the figure, in addition to the aforementioned delay circuits 7, 7°, . . . and adder circuit 8, correlators 17, 17.・And control circuit 18
and a delay circuit controller 19. The above correlator 1
7 is a plurality of transducer elements 1, 1 . One of the received signals from . ... to the adder 8 via gates 21, respectively, to A/D converters 2o provided in parallel in the middle of the signal lines going from the adder 8 to the adder 8. For example, a signal from the center element of several transducer elements involved in transmitting and receiving ultrasonic waves within the probe 2, or a received signal from the amplifier 5 of channel #3 in FIG. 1, is used as a reference signal. and signals from other elements, ie channel #1. #2. #
4. The received signal from amplifier 5 #5 is input to each of the correlators 1 as an input signal for determining the correlation with the reference signal.
7.17. ... to calculate the correlation function between both signals in Game 1.
It is designed to be executed for a specific period given by ~21. Further, the control circuit 18 operates on each of the correlators 17.1-7. The output signal of the calculation result is input and the amount of delay to be given to the received signal other than the reference signal is determined so that the correlation function is maximized. Note that this control circuit 18 includes each of the correlators 17, 1.7, . . . . 112=, which sends a control signal S□ to the games h21, 21. A control signal S2 for opening and closing the gate is sent to... Furthermore, the delay circuit controller 19 inputs the signal output from the control circuit 18 and sets the optimum delay time for each of the delay circuits 7.7, .

Next, the principle of calculating the correlation function between the reference signal and other received signals using the correlator 17 and determining the amount of delay at which the correlation function is the largest will be explained. First, the correlation R(t) between the time function v1(t) and v2 (at t+) obtained by shifting this by time τ can be expressed mathematically by the following equation.

This formula is obtained by taking the product of the function ■□ (1) and v2 (+) and integrating the product. That is, the correlation between two time functions is expressed by time movement (delay), multiplication, and integration as shown in equation (3).

The physical quantities discussed below are originally continuous analog variables, but in order to perform digital signal processing,
These variables (time, amplitude, etc.) are quantized into discrete values. That is, if the integration in the above equation (3) is changed to addition and the time function takes a constant discontinuous value, the above correlation can be expressed in the following form.

R(n) = Σv, (k) ・V2(k+n) −(
4) 1(ψ where k and n are respectively t in the above equation (3)
is a variable that means τ. The correlation R(
In the actual calculation of n), the calculation of integration over infinity is not performed, and k is set to take a value within a certain range. The range that k should take is, for example, two functions V□(k)
and V 2 (k + n), the portion to be sampled, their periodicity, etc. to be determined. Based on Equation (4) expressed by the above-mentioned integration of discontinuous numerical values, calculation of the correlation R(n) can be realized by a digital circuit.

Hereinafter, the configuration and operation of digital circuit correlators (corresponding to the correlator 17 shown in FIG. 1) will be explained, starting from the simplest ones.

First, in order to explain the principle of a correlator using a digital circuit, an example of the simplest correlator 17 is shown in FIG. The correlator 17 includes a reference shift register 22, a signal shift register 23, an exclusive NOR gate 24, and an adder 25. The reference shift register 22 receives, for example, a received signal from the amplifier 5 of channel #3 shown in FIG. 1 as a reference signal, and stores this reference signal. On the other hand, the signal shift register 23 is connected to channel #1 shown in FIG. #2. #4. #5 amplifier 5
The received signals from the two are input as input signals for correlation, and these input signals are stored. . Note that both of the shift registers 22 and 23 have a length of n bits.

The exclusive NOR gate 24 connects both shift registers 22
．． It compares each bit of 23 corresponding bits and outputs a 1 or 0 signal, and both shift 1 to register 22
．． Each bit is provided for each of the 23 corresponding bits. The adder 25 includes the exclusive NOR gates 24, 24 .
. . . It integrates the output signals and outputs the integration results as correlation data. Here, the shift amount of the data in the signal shift register 23 is time-shifted (delayed).
Therefore, the above configuration and operation perform delay, multiplication, and integration. Such a correlator based on a digital circuit is realized using a monolithic IC and is commercially available.

Next, the data size as shown in FIG. 2 is based on the principle that the delay between the bit patterns of two similar signals, such as the reference signal and the input signal, is determined using a 1-bit correlator 17. will be explained with reference to Table 1 below.

Table 1 shows numerical examples of correlation data obtained by determining the delay between the bit pattern input as the original signal and the bit pattern input as the input signal. First, the reference shift register 22 is filled with the bit pattern of the reference signal shown in Table 1 above, while the signal shift register 23 is filled with the bit pattern shown in Table 1 above! After the bit pattern of the original signal of the signal is satisfied, an operation is performed in which only this input signal is sequentially shifted, for example, one bit at a time to the p delay side. Then, for each delay operation, the correlation between the two is determined based on the degree to which the value of 1°O in the bit pattern of the reference signal matches the value of 1 and 0 in the bit pattern of the input signal.

That is, the exclusive NOR gate 24 shown in FIG. 2 outputs 1" if the numerical values of each bit of both shift registers 22 and 23 match such as 0, 0 or 1, 1ψ, and outputs Kl 011 if they do not match. These signals are successively integrated by an adder 25 and output as correlation data.

In this way, the point where the correlation data, which is the output signal of the correlator 17, is the largest is the peak point of two similar signals.
This is where the pattern matches. Therefore, it can be seen that the delay between the two signals is determined by the relationship between the magnitude of the correlation data and the delay given to the input signal.

Next, FIG. 3 shows an example of a correlator 17' which handles data obtained by A/I converting an analog signal and calculates a correlation. For example, when human signal data is sent from the 4-bit A//D converter 26, the 1-bit correlator 17 shown in FIG. 2 calculates the correlation between two similar signals. It is not possible. Therefore, as shown in Figure 3, 4 pins 1
- four 1-bit correlators 17, 17, . . . are provided in parallel on the output side of the A/D converter 26, and
Correlation processing is performed for each digit of the output data of the converter 26. These correlators 17, 17 . ...and adder 2
7, there are dividers 28, 28 . ... are provided, and each of the correlators 17.17. The output data of each digit from . Here, the divider 28.28.・For example, the size of the weight in ÷2. ÷4. If ÷8, then each output data is 1 pixel to the right. Correlation can be found by shifting 2 or 3 bits. In this way, correlation data that reflects the degree of coincidence with the reference signal can be obtained by weighting each digit of the data of the binary input signal.

Next, FIG. 4 shows an example of a correlator 17'' that calculates a strict correlation between two functions consisting of parallel data of multiple digits of binary numbers when there are two functions. In order to calculate the correlation between the data of the reference signal and the data of the input signal as a function (this is a result of A'/D conversion of an analog signal into a binary number of 3 bits I), as shown in Fig. 4, Nine 1-bit correlators 17, 17 .
... are connected in a 71-lix configuration, and the numbers corresponding to each digit of each signal data are connected to the nine correlators 17.
, 17, and these correlators 17, 17 . ...
The output data of each digit is given weight for addition by a divider 28, and is integrated by an adder 27.

=19- Here, we will explain the operating principle of the X-correlation device 17'' having the configuration shown in FIG. Then, the correlation formula becomes:

Here, U and m are continuous values of functions and X corresponding to the bottom in the above equation (3) or k and n in the above equation (4), respectively. With this Fl or continuous value 3
Since it is discrete data that has been A/D converted into binary numbers from 1 to 1, h・22+j・21+k・21′=4h+2j+kx・
It is assumed that it is expressed by the number 22+y・21+z・21′=4X+2y+z. In addition, h+ J+ kn X+y, Z
is a binary value of 1 or 0. Then, the correlation of the product + (Q) ・x (Q+m) in the two-disciplined equation (5) is (4h+2j+k)x (4x+2y+z)=16xh
+8 (zj+yh) +4 (xk+yj+zh)+
2 (yk+zz) +zk ... It can be expressed by the formula (6). This formula is the numerical data h of each digit that has been A/D converted into a 3-bit binary number of h and X.

A 1-bit correlator 17.
．． ... to calculate the correlation, 16.8, 4 of the above equation (6)
, 2.1 through the divider 28, and the adder 27 adds up the weights. In this way, the continuous measurement and x tt A/D converted data can be correlated over a constant length of data N by the correlator 17# having the configuration shown in FIG. Here, if the delay amount m of the input signal data with respect to the reference signal data is changed (this corresponds to internally appropriately shifting the input signal data by 1- with respect to the input reference signal data)
By determining m for which the correlation R(m) in the above equation (5) is the largest, it is possible to know the delay amount m for which the correlation between h and X is the strongest.

From the above, we can find the correlation between two similar functions v1(t) and v2(t+τ) that take continuous values as shown in Equation (3) in a certain region such as t<t<t2, and find the highest correlation. It can be seen that the increasing delay amount τ can be obtained using a correlator using a digital circuit.

In the embodiment shown in FIG. 1, each correlator 17 has the configuration and function shown in FIG.
shall consist of. Note that in each correlator 17 shown in FIG.
,1. . . . Symbol B is an input terminal for the data of the reference signal from the center transducer element 1 of channel #3, and symbol C is the input terminal for internally shifting the data of the input signal. A clock signal (control signal S1) for changing the delay amount m in the equation (5) above.
This is the input terminal of

Next, the operation of the phasing circuit 6' in the ultrasonic diagnostic apparatus configured as described above will be explained. First, each amplifier 5
,5. The received signals from... are sent to delay circuits 7 and 7, respectively.
7. ... and a predetermined delay time is given. Next, the delay circuits 7, 7 . The output signals from... are input to the adder 8, and are also input to the A/D converters 20 provided in parallel in the middle. And this A
After being converted into a digital quantity by the /D converter 20, the received signal is input to the correlator 17 only for a specific period given by the gate 21. At this time, in FIG. 1, the received signal from the amplifier 5 of channel #3 is input as a reference signal to the input terminal B of each correlator 17, and the other channels
1. #2. The received signal from the amplifier 5 of xi, #5 is input to the input terminal A of each correlator 17 as an input signal for determining the correlation with the reference signal. This input data, like the output signal of the A/D converter 20, has a size of, for example, 3 bits, and also has a size of, for example, 32 bits with respect to time. At this time, the above-mentioned correlator 17 The signal data input to the input terminals A and B is taken in only for a specific period at a timing centered on the convergence point of the ultrasonic beam by opening and closing the gate 21. The data of the reference signal and the data of the input signal thus taken in are correlated with each other by the correlator 17.

Here, channel #1. #2. #3. #4゜z3- The received signal from each amplifier 5 of #5 is sent to each A/I) converter 2.
The signal data digitized at 0 is converted to Xz (
Q+m), X2 (12+m), h (ff+m).

Assuming that x4(Q+m), X, and (Q+m), the correlation obtained by the correlator 17 is as follows.

Rp (m) = Σh (Q) ・xp (Q+m)・
= (7) Here, p = = 1.2, 4.5 Note that h (Q) and xp (Q + m) are 3-bit data, and the data length is 92 bits. . And channel #1. #2゜#4. By giving an appropriate delay to the input signal from each amplifier 5 of channel #5, the correlation Rp (m
) is the largest, the delay amount m is determined by the control circuit 18 as follows:
Control signal S1 sent to input terminal C of each correlator 17
and the output signal S output from the corresponding correlator 17. That is, the control circuit 18 performs an operation to obtain the value of the delay amount m that maximizes the correlation Rp (m) every p=1.2 and 4.5. Then, the signal of the delay amount m determined by the control circuit 18 is sent to the delay circuit controller 19. This delay circuit controller 19 includes the controller 1
A signal with delay amount m inputted from lt18 is sent to each delay circuit 7, and this delay circuit 7 outputs the signal of channel #1. #2.
#4. A delay amount corresponding to the above data m is given to the input signal from #5. At this time, m=0 and the above correlation Rp(
m) indicates the maximum value. In this way, the phasing circuit 6' shown in FIG. 1 corrects the variation in the delay of the received signal caused by the non-uniform sound velocity at the diagnostic site of the subject, which is the path of the reflected echo shown in FIG. , by correcting the delay time of each delay circuit 7 according to the value of the delay amount m, each of the delay circuits 7 described above
The output signals of can all be in phase. As a result, a phasing circuit 6' having an automatic focusing function that acts on non-uniformity of the sound velocity in the ultrasonic transmission medium is realized.

In actual use of the device, delay correction data is captured for all scanning lines in the first frame when diagnosing the same part of the subject, all of this correction data is stored, and the above correction data is stored in the next frame. The received signal may be phased using the following. Next, such an operation will be explained with reference to the timing diagram shown in FIG.

Here, in FIGS. 5(a) to (h), the vertical axis represents the magnitude (voltage) of each signal, and the horizontal axis represents time in the same time phase. First, (,) to (c) of the same figure show each transducer element 1, 1. For example, among the received signals received on channel #1. #2. This is the output signal from the delay circuit 7 corresponding to #3. At this time,
The ultrasonic beam 11 is at time t. Figure 5 (
Shown in a) to (c). If time t3 corresponds to the reflected echo from the convergence point, then at time t3, the phase of the output signal corresponding to channel #3 matches that of the output signals corresponding to channels #1 and #2. When inputted manually to the adder 8, the ultrasonic beam 11 is in the best convergence state.

Next, FIG. 5(d) shows a control signal S2 for opening the gate 21 shown in FIG.
/D converter 20, 20. The delay circuits 7, 7 . . . are converted into digital quantities by . The output signals of... are input to the correlator 17 for a period of t2 from the time t. Figure 5 (e
) shows an example of a received signal that has been A/D converted and input to the correlator 17. Assuming that the data of the input signal input to the input terminal A of this correlator 17 and the data of the reference signal input to the input terminal B are, for example, 3 bits, and the data length from time t□ to t2 is 32 bits, Figure 5 (e)
indicates one of the 3-bit numerical values representing the amplitude of a certain channel. The data input in this way is transmitted from time t to time t, as shown in FIG. 5(f) and (g).
5, each correlator 17, 17 . An operation is performed to obtain a correlation function each time the delay amount m is changed from 1 to m.

The delay time of each delay circuit 7゜7, . Time t. z7- is executed by the control circuit 18 and the delay circuit controller 19 at time t6. Thereby, the delay time can be corrected so that the ultrasonic beam is converged in the best condition.

Although FIG. 1 shows an example applied to an electronic linear scanning ultrasonic diagnostic apparatus, the present invention is not limited to this, and the changeover switch 16 in the probe 2 is omitted, and the transducer element 1 is ,1. Narrow the width of ... and increase the number, for example, to 3.
The number of amplifiers is 2 to 64, and the number of amplifiers is 5.
By increasing the number of channels of the delay circuit 7 and making the delay time that the delay circuit 7 can take longer, the present invention can be similarly applied to an electronic sector scanning type ultrasonic diagnostic apparatus.

〔Effect of the invention〕

Since the present invention is configured as described above, the correlator 17 in the phasing circuit 6' processes one of the received signals inputted from the plurality of transducer elements 1, 1°, . . . via the delay circuits 7, respectively. Using one as a reference signal, a correlation function between this signal and other received signals is calculated for a specific period, and the control circuit 18 uses the correlator 17
By inputting the output signal from the control circuit 18 and determining the amount of delay to be given to other received signals so that the above-mentioned correlation function becomes the largest, and inputting the signal from this control circuit 18 to the delay circuit controller 19, this delay can be adjusted. The optimum delay time can be set for the delay circuit 7 using the circuit controller 19.

Thereby, even if the sound velocity distribution is not uniform depending on the diagnostic site of the subject, the delay time can be corrected so that the ultrasound beam is converged in the best possible condition. Therefore, the autofocus function can be performed stably and in a short time, and the image quality can be improved without impairing the real-time nature of the image. From this, the clinical value of the ultrasonic diagnostic apparatus can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus according to the present invention, FIG. 2 is a block diagram showing an example of a correlator using the simplest digital circuit, and FIG. 3 is a block diagram showing an example of a correlator using an analog signal.
, a block diagram showing an example of a correlator that calculates a correlation by handling /D-converted data, the first part is a block diagram showing an example of a correlator that calculates a strict correlation between functions consisting of two binary multi-digit parallel data 5 is a timing diagram for explaining the operation of the phasing circuit according to the present invention, and FIG. 6 is an explanatory diagram showing the principle of the electron focusing method of ultrasound beams used in ultrasound diagnostic equipment. , FIG. 7 is a block diagram showing a conventional ultrasonic diagnostic apparatus having an automatic focus function. DESCRIPTION OF SYMBOLS 1... Transducer element, 2... Probe, 5... Amplifier, 6'... Phaser circuit, 7... Delay circuit, 8
... Adder, 12... Transmission pulse generator, 13.
...Detector, 14...Display device, 15...Control device, 17, 17', 17"...Correlator, 18.
...Control circuit, 19...Delay circuit controller, 20
...A/D converter, 21...gate. Applicant Hitachi Medical Co., Ltd.

Claims (1)

[Claims] a probe in which a plurality of transducer elements are arranged and transmits and receives ultrasonic waves; a transmitting pulse generator that applies a drive pulse for emitting ultrasonic waves by giving a predetermined delay time to each of the transducer elements;
a phasing circuit including a delay circuit that gives a predetermined delay time to the received signal from each transducer element of the probe, and an adder that adds the received signals output from each delay circuit and whose phases are aligned; , an ultrasonic diagnostic apparatus having a detector that detects a signal phased by the phasing circuit, and a display device that displays the output signal from the detector as an image. A correlator that uses one of the received signals from the element as a reference signal and calculates the correlation function between this signal and other received signals for a specific period, and calculates the correlation function between this signal and other received signals for a specific period, and An ultrasonic diagnostic apparatus comprising: a control circuit that determines the amount of delay given to a signal; and a delay circuit controller that inputs a signal from the control circuit and sets an optimal delay time for the delay circuit. .