JP2671633B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus having a dynamic focus function.

[0002]

2. Description of the Related Art Ultrasonic imagers are used to detect scratches and defects in materials and structures by utilizing the reflection and transmission of ultrasonic waves, but they are also widely used in medical fields and are used as diagnostic data. Is used as.

The principle of ultrasonic inspection or diagnosis will be described with reference to FIG. When ultrasonic waves are transmitted to the subject from each of the transducers arranged in an array, that is, the ultrasonic transducers, the ultrasonic waves hitting point D1 in the subject are reflected and return to the transducer again. At this time, since the distance between D1 and each transducer is different, the returning time of the reflected wave varies depending on the position of the transducer.

Therefore, a large delay is given to the oscillator returning fast (the one in the center of the oscillator with the halftone dot in the figure),
A delay line that gives a small delay is passed through the vibrator that returns late, and the delay amount is controlled so that the reflected waves of each vibrator have the same time at the addition points. The waveform surrounded by the dotted line closer to the delay line shows the waveform after the delay processing is performed in this way. The result of adding these waveforms is the waveform surrounded by the dotted line with the smaller result. When this waveform is subjected to luminance conversion and displayed, the inside of the target object is displayed as shown on the monitor. The dotted arrow on the monitor corresponds to the arrow shown by the solid line in the target object, and this line is called the scanning line. The dynamic focus function refers to a function of changing the focal position on the scanning line moment by moment during reception. Here, the example of focusing using only the delay line was given, but part of the delay line was replaced with a phase shifter,
Focusing can also be achieved by a combination of phase control and delay time control.

[0005]

Japanese Unexamined Patent Publication No. 56-112234 discloses a technique of using a two-phase tap-switching phased array, but requires two expensive delay line groups. In addition, since the entire phased array having a long delay time is switched, it is difficult to shorten the switching cycle. The reason why two delay line groups are required is that the tap position of the delay line is switched in order to change the delay amount, but this causes noise. In order to prevent this, two delay line groups are provided, and while one delay line group is in use, the tap of the other delay line group is switched. Also,
A phased array is a delay system that electronically delays an array of transducers so that the focus can be set freely.

USP4140022 discloses a technique of using a mixer. However, since this technique only controls the phase of the carrier wave of the received signal, it is possible to use dynamic mixer as in recent years.
For a probe with a large aperture in which the phase change during focusing changes nearly three times the wavelength of the ultrasonic signal, when the center frequency of the ultrasonic signal changes due to attenuation in the living body, the depth at which the dynamic focus becomes optimal is Degradation of the beam occurs except near the position. In order to prevent this deterioration, one scanning line must be created by dividing the depth direction into several stages and combining the received signal groups obtained by performing optimal dynamic focus control for each depth. Of course, in order to obtain one tomographic image, the amount of signals required to obtain several tomographic images is required, and the original purpose of the dynamic focus is real-time performance. In addition, 2-3 in the depth direction
Degradation of the beam cannot be prevented by only dividing the stage.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic diagnostic apparatus which is not easily affected by the attenuation of a living body.

[0008]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 2 is an ultrasonic transducer element arranged in a predetermined shape, 1 is a desired transmission driver of the transmission / reception circuit 3, and ultrasonic pulses are applied to the subject by the ultrasonic transducer element 2 corresponding to the transmission driver. A transmitting circuit 3, 4, 5, 6, 7 for transmitting and outputting a control signal for emitting an ultrasonic pulse focused on a desired depth position of the subject is provided from the subject of the ultrasonic pulse. This is a receiving circuit that receives reflected waves from a desired one of the ultrasonic transducers 2 and performs control and phase control to generate delay times corresponding to the received signals, and then adds them. Reference numerals 8 and 9 are display means for displaying the added reception signal as an image. The receiving circuits 3, 4, 5, 6, and 7 are a receiving amplifier of the transmitting / receiving circuit 3 including a transmitting driver and a receiving amplifier, and an amplifier for varying at least two gains per one element of the ultrasonic vibration element 2. It is desirable to have a multiplication circuit 4 having a circuit configured to control the allocation of the gain of each amplifier, and the output of each amplifier corresponding to the output of each ultrasonic transducer 2 of the multiplication circuit 4. Switch circuit parts 5 and 6 that switch / connect to the output terminals of
A delay line circuit 7 that has a tap corresponding to the output terminals of the path units 5 and 6 and that changes the delay amount of the input signal depending on the position of the tap, and two gains that are components of the multiplication circuit 4 The two output terminals of the amplifier that makes variable are paired with appropriate two taps of the delay line circuit 7, and this pair is switched to an arbitrary pair out of a set constituted by selecting an appropriate interval,
Allow connection.

Further, the multiplication circuit 4 is composed of a first circuit and a second circuit each having two variable gain amplifiers per one element of the ultrasonic vibration element 2, and the delay line circuit 7 is appropriately provided. Two taps as a pair, the pair is selected at an appropriate interval, and a second set is formed by a pair having an interval between the two, and two variable gains of the first circuit are formed. -The two output terminals of the amplifier can be switched and connected to any pair of the first set, and the two output terminals of the two variable gain amplifiers of the second circuit can be switched to any pair of the second set.・ Be able to connect.

[0010]

Further, the multiplication circuit 4 causes the ultrasonic vibration
Two variable gain amplifiers are provided per moving element 2
Then, the first variable gain amplifier outputs a positive-polarity first output and a negative-polarity second output, and the second variable gain amplifier outputs a positive-polarity third output and a negative-polarity fourth output. In addition, the tap interval of the delay line circuit 7 is 1/4 cycle of the specific frequency cycle within the change range of the carrier frequency of the ultrasonic signal due to attenuation in the living body and is adjacent to the delay line circuit 7. When two taps are paired and the delay tap pairs are numbered in the order of the delay amount, the two taps of the odd-numbered pair of the delay line circuit 7 have two differential outputs on one side of the two differential outputs. Connected to the 2 taps of the even-numbered pair and the polarity of 2 on the other side
Make sure that the output is connected, and when the gain control of the two variable gain amplifiers is represented by cos (p), sin (p) when connecting to an odd number, two variable gain amplifiers when connecting to an even number. Make the gain control of the amplifier cos (−π + p), sin (−π + p).

Further, the delay time between taps of the delay line constituting the delay line circuit 7 is the probe frequency of 2.5 MHz,
For 3.5MHz, 5.0MHz, and 7.5MHz, 6: 4:
The ratio becomes 3: 2, and an integer number of taps for all probe frequencies are inserted during 12 tap intervals of the delay taps for 7.5 MHz probe.

[0013]

First, the functions of the phase control and the delay line will be described. A received signal for one element of the ultrasonic vibration element 2 is represented by the following equation. u (t) = a (t) sin (ωt + ψ) (1) FIG. 3A shows the formula (1), and the amplitude a (t) represents the envelope component indicated by the broken line. Where ω is the angular frequency and ψ
Represents the phase angle. A signal delayed by t0 time from the equation (1) is expressed by the following equation. u (t−t0) = a (t−t0) sin (ω (t−t0) + ψ) (2) FIG. 3B shows the equation (2). The delay line circuit 7 realizes t0, which is called a delay amount t0. In this case, the envelope component a
Both (t) and the carrier wave are delayed by t0 time. Next, if only the carrier of the signal is delayed by t0 time, it is expressed by the following equation. u '(t-t0) = a (t) sin ((omega) (t-t0) + (psi)) (3) FIG.3 (c) represents Formula (3). The envelope component is the same as that in (a) and the carrier wave is in the same phase as in (b). The multiplication circuit 4 that performs the phase control realizes this operation.

In the phasing process represented by the equation (2), since the waveform itself can be moved by t0, the signals from the respective vibrating elements can be perfectly matched with each other, so that a large focusing effect can be obtained. Since the phasing process represented by the formula does not delay the envelope component, the signals from the respective oscillators cannot be matched. However, a close match can be achieved. However, the phasing method according to formula (2) is more complicated and expensive than the case according to formula (3). Therefore, a large phasing process is performed stepwise by the delay line circuit 7 that realizes the formula (2), and a small phasing process within the step width is performed by the multiplication circuit 4 that realizes the formula (3).

In this way, the phase of the carrier wave is controlled by the multiplying circuit 4, and while the change in the delay amount is small (for example, λ is the wavelength of the ultrasonic signal, ± 0.5λ or less), only this phase control is performed. Focus the sound beam. When the change in the delay amount becomes large, the tap of the delay line circuit 7 is switched by controlling the phase of the multiplication circuit 4, changing the setting of the switch circuit 5, and switching the switch circuit 5 by the switching circuit 6, thereby controlling the phase of the carrier wave. The focus control amount is set not to be too large, for example, ± 0.5λ or less. In this way, by suppressing the focus control amount by the phase control of the carrier wave, it is possible to reduce the influence of attenuation by the living body.

[0016]

[0017]

[0018]

[0019]

Embodiments of the present invention will be described below with reference to the drawings. Since the basic configuration of this embodiment is the same as the principle diagram shown in FIG. 1, a detailed description of FIG. 1 and constituent parts of FIG. 1 will be described with reference to the drawings. In FIG. 1, reference numeral 1 is a transmission circuit that produces a signal for controlling a transmission driver circuit.
2 is an array of ultrasonic transducers, 2-1 to 2-n
Are individual ultrasonic transducers. 3-1 to 3-n are transmission / reception circuits (transmission driver, reception amplifier), 4 is a multiplication circuit group, 5 is a SW circuit group which is a contact circuit group for tap selection of the delay line circuit 7, and 6 is noise. Is a delay circuit circuit, 8 is a log amplifier, and 9 is a display.

The transmitting circuit 1 sends a control signal for emitting an ultrasonic pulse focused to a desired depth position of the subject to a desired transmitting driver circuit of the transmitting / receiving circuits 3-1 to 3-n. The ultrasonic transducer 2 corresponding to the transmission driver circuit is driven to emit a transmission pulse to the subject. The reflected wave of the transmission pulse from the subject is received by each of the ultrasonic transducers 2-1 to 2-n, passes through the receiving amplifier of the transmission / reception circuit 3, and only the signal from the desired transducer 2 has an appropriate gain. For example, the reception gain at the aperture position of the reception aperture configured by the selected vibrating element 2 is apodized in a Gaussian curve shape.
) And is led to the multiplication circuit group 4. The apodization in this case is a process of reducing the gain at the time of reception or the gain at the time of transmission toward the vibrating element 2 closer to both ends of the aperture.

The apodization of the received signal may be performed by changing the gain of the reception amplifier of the transmission / reception circuit 3.
It is also possible to set it by the multiplication circuit group 4. Further, apodization may be set to 0 for unnecessary received signals. Also, during dynamic focusing, the aperture is gradually increased according to the depth at which the received signal returns.
This may be achieved by gradually changing the apodization of the vibrating element 2 outside the opening end, which is initially set to 0, to an appropriate value.

In the multiplication circuit group 4, one of the ultrasonic vibration elements is
Two kinds of gains per element, or signals different only in gain and polarity are output, and are connected to the appropriate adjacent taps of the delay line circuit 7 via the SW circuit group 5 and the switching circuit group 6,
By allocating the gains of these two types of signal lines performed in the multiplication circuit group 4, the phase of the carrier wave of the received signal is controlled to a desired phase. However, when the multiplication circuit group 4 has two systems, signals of 2 types × 2 systems per one element of the ultrasonic vibration element 2 are output from the multiplication circuit group 4.

The switching circuit group 6 includes SW circuit groups 5-1 and 5
-One of the two paths of -2 is selected, the tap selection of the delay line circuit 7 is determined by the selected SW circuit group 5, the received signal is focused, and the output signal of the delay line circuit 7 is logged. It is logarithmically converted by the amplifier 8 and sent to the display device 9 to be displayed as an image.

In the circuit system which is not selected, the following set value is set, and at the timing of the next dynamic focus, the switching circuit 6 performs noiseless switching to select the focus at the next depth position. . By alternately performing dynamic focusing in two systems, it is possible to perform switching several tens times in the depth direction on the scanning line.

Next, the multiplication circuit will be described in detail with reference to FIG. FIG. 4 illustrates the function of the multiplication circuit group 4, and is a configuration diagram of one element of the ultrasonic vibration element 2. FIG. 2 is a configuration diagram for one element when the multiplication circuit group 4 shown in FIG. 1 has one system or only one system of two systems. Further, for simplification of description, the SW circuit group 5 and the switching circuit group 6 in FIG. 1 are omitted, and the delay line circuit 7 is connected to the selected adjacent tap positions T _i and T _{i + 1} . This is illustrated.

A is any one of the transmission / reception circuits 3-1 to 3-n.
It is a receiver output signal for a circuit, and C _c = A × B _c , by two multipliers M _C and M _S having this signal as one input.
A circuit that produces two kinds of signals having a gain of C _s = A × B _s or a polarity different from the gain is a constituent element of the multiplication circuit group 4. Generally, the received signal A is approximately A =
It is expressed as a (t −tdj) sin (ω · t −Φdj). Where a (t −tdj) is the amplitude modulation term, and tdj is each vibrating element 2
The delay time due to the path length of the received signal received at, Φdj, is the phase shift of the carrier wave.
Each has a different value. Also, t is time and ω is the angular frequency of the received signal carrier.

Further, the taps T _{i + 1} and T _{i of the} delay line circuit 7
Let tdl be the tap interval of, and let tdi be the total delay time obtained by integrating the delay amount from T _i to the minimum delay time T _o . The output signal Edlo of the delay line circuit 7 based on only the two signals in T _{i + 1} and T _i in FIG. 3 is B _c = a1, B _s = a2.
Then, the following equation is obtained. Where a1 and a2 are multipliers M _C and M
_This is a control signal for _S gain setting.

Edlo = a1 · a (t-tdj-tdi) sin (ω
・ T −Φdj−ω ・ tdi ＋＋ a2 ・ a (t −tdj − (tdi ＋
tdl)) sin (ω ・ t −Φdj−ω ・ (tdi + tdl)) τ1 ＝ t −tdj −tdi, τ2 ＝ t −Φdj / ω−tdi Edlo ＝ a1 ・ a (τ1) sin (ω ・τ2) + a2 ・ a (τ1
−tdl) sin (ω ・ (τ2-tdl))

Further, the amplitude modulation term a (t) has only a frequency component lower than that of the carrier wave. Also, tap interval tdl
Is less than ¼ of the carrier wave period Tp, so a (τ
1) ≈a (τ1-tdl). Therefore, apply as follows. Edlo ≒ a (τ1) [a1 ・ sin (ω ・ τ2) ＋ a2 ・ sin
(Ω ・ (τ2-tdl))]

Further, with p as an arbitrary phase, Edlo = a (τ1) · sin (ω · τ2-p) by a1 and a2, that is, p
To obtain a signal whose phase is controlled only by Φdl = ω ・ td
Let l be a1 = cos (p) −sin (p) ・ cos (Φdl)
It suffices to set a1 and a2 so that / sin (Φdl) and a2 = sin (p) / sin (Φdl). The ultrasonic signal is
Although the value of ω changes due to the attenuation in the living body, Φdl may be determined at one point within the range of ω. In the case of a 3.5 MHz probe, a1 and a2 may be calculated by taking a value of ω for 3.5 MHz or a slightly lower value of ω in consideration of attenuation.

In the multiplication circuit group 4, when apodizing is performed, the apodizing value of the ultrasonic vibration element is set to
Let apj be a1 ＝ apj ・ (cos (p) −sin (p) ・ cos (Φdl) /
sin (Φdl)) a2 ＝ apj ・ sin (p) / sin (Φdl)
Set 1 and a2.

When only the interpolation between the taps T _{i + 1} and T _i is used, a good interpolation result can be obtained for any tap interval tdl such that Φdl ≦ π / 2. When performing extrapolation widely, for example, when performing phase control of a carrier wave in the range of -π to + π, it is better to set Φdl = π / 2.

Although the effect of lowering the carrier frequency due to the attenuation of the ultrasonic signal by the living body is smaller if the tap is used only for interpolation between T _{i + 1} and T _{i and} the tdl is made smaller, the delay line circuit The number of 7 taps is increased, and SW circuit group 5
The switching circuit group 6 also increases. In this embodiment, -π to +
A case will be described where the phase control is performed in the range of π.

FIG. 5 shows a concrete example in the case of performing the phase control in the range of -π to + π. If Φdl = π / 2 is selected, a1 = cos
(P), a2 = sin (p). If phase control is performed in steps of λ / 16, 16 types of control values are required,
Since a1 and a2 are periodic functions, a, b, c, d, and
The entire range can be controlled by eight types of control values, e, f, g, and h. This control value can be created by eight D / A converters, and can be commonly used for all ultrasonic transducers 2.

Further, by using the control signals B0 to B3 of 4 bits,
If SI and SO are created by EOR of 1, control signals of B _s and B _c of FIG. 4 can be obtained by the 8 to 1 analog switches 302 and 303. Note that Ad is an analog switch 302, 303
It is a control address of 3 bits for selecting 8 contact points of 0-7.

In this way, the 4-bit control signal B0-
By B3, the selected taps T _i , T of the delay line circuit 7
_It is possible to control the phase of the carrier from -π to + π from the center of _{i + 1} (hatched portion). Also, analog switches 302, 30
It is of course possible to configure the circuit with two D / A converters instead of 3, and in this case, if a decoding section is provided in the control input system of the D / A converter, apodization becomes easy.

FIG. 6 shows an embodiment in which the multiplication circuit group 4 has two systems.
There are system multiplication circuit elements 401 and 402. The multiplication circuit elements 401 and 402 have the same functions as those described with reference to FIGS. The switching circuit group 6 in FIG. 1 is omitted for simplification of description. A is a received signal output from the transmission / reception circuit 3. Although FIG. 6 shows only one element of the ultrasonic vibration element 2, the multiplication circuit elements 401 and 402 are required for the number of elements (n pieces shown in FIG. 1).

Further, a contact for a reception signal from another ultrasonic vibration element 2 is also included (not shown in 403 and 404 though each element 2 through 403 or 404). ), The signal sent to the delay line circuit 7 is
The circuit configuration is such that the addition is performed within the circuit. Where 403, 404
Shows a part of the SW circuit groups 5-1 and 5-2.

When the multiplication circuit elements 401 and 403 (system P) are performing the focusing action, the multiplication circuit element 402
And 404 (system Q) are separated from the delay line circuit 7 (not shown), and the next control values are the multiplication circuit elements 402 and 404.
Is set to In the multiplication circuit element 401, two kinds of gains or signals having different gains and polarities are output per one element of the ultrasonic vibration element 2, and the one in the SW circuit group 403 is output.
A pair of two contacts, eg 403- 3 and 403-4, is selected and the appropriate adjacent taps of the delay line circuit 7 (403-3 and
In the case of 403-4, it is connected to 2 taps of Dp2) (a large delay control of an integral multiple of 2 × tdl is performed by the selection of taps), and by allocating the gains of these two types of signal lines ( This is performed by the multiplication circuit element 401.) The phase of the carrier wave of the received signal is controlled to a desired phase. The same operation as described above is performed for the other ultrasonic transducers 2, and the received signals are added on the delay line circuit 7 to focus on the desired depth position.

At the next dynamic focus timing, the Q side is connected to the delay line circuit 7 and the P side is disconnected. Hereinafter, P and Q alternately perform their functions. Dp1, Dp
2, ..., Dq1, Dq2, ... can be tapped at intervals of 4 × tdl. Also, Dp1, Dp2, ... And Dq1,
Dq2, ... are the same tap positions (eg Dp1, Dp2, ...
・ ・ Use only the tap position of. ), The above is possible, but when switching between P and Q, for example, with P
When Dp1 is selected and Dp2 is selected by Q, a delay amount difference of 4 × tdl occurs at the time of switching. Dp1
, Dp2, ... And Dq1, Dq2, .. are shifted by 2 × tdl, the difference in the switching delay amount can be reduced to 2 × tdl or less. However, the tap at the left end of Dp1 cannot be covered in the range of phase control from Dq1 to π, but there is no problem if the origin of the delay amount is set at the right end of Dp1 and the delay amount is calculated.

FIG. 7 shows an embodiment in which the multiplication circuit group 4 has one system, and there is one system of multiplication circuit element 501 for each ultrasonic vibrating element 2. Multiplication circuit element 501
Has the same function as described with reference to FIGS. Since the multiplication circuit element 501 is shared by the P system and the Q system, B
Noise when changing the control values of _c and B _s becomes a problem. Therefore, the low bus filter Fc501-1, Fs501
Insert -2 to reduce noise when changing control values. B _c, B _s from M _C, the path of the input of the M _S, not included in a high carrier frequency, it is possible to filter the low frequency commensurate with the switching period (a few microseconds). Further, the switching circuit group 6 shown in FIG. 1 is omitted to simplify the description.

A is a received signal output from the transmission / reception circuit. Although FIG. 7 shows only one element of the ultrasonic vibration element 2, the multiplication circuit element 501 is an element (n pieces shown in FIG. 1).
Just need. In addition, each element 2 to 502 (or 503)
A signal sent to the delay line circuit 7 via (via a contact (not shown in the drawings 502 and 503 for receiving a signal from another ultrasonic transducer 2) is also included). The circuit configuration is such that addition is performed in the delay line circuit 7. 502 and 50
3 shows a part of the SW circuit groups 5-1 and 5-2.

When the system P is performing the focusing action, the system Q is separated from the delay line circuit 7 (not shown), and the next control value is set to 503. In the multiplication circuit element 501, one element of the ultrasonic vibration element 2
Two types of gains or signals with different gains and polarities are created, and the output is output as a differential output.
A set of two contacts within 502, for example 502 -3 and 502 -4, is selected and the appropriate adjacent taps (50
In the case of 2-3 and 502-4, it is connected to 2 taps of D2) (a large delay control of an integral multiple of 2 × tdl is performed by the selection of taps.) The allocation of the gains of these two types of signal lines By this (performed by the multiplication circuit element 501), the phase of the carrier wave of the received signal is controlled to a desired phase. The same thing as above is performed for the other ultrasonic transducers 2, and the received signals are added on the delay line circuit 7 to focus on the desired depth position.

At the next dynamic focus timing, the Q side is connected to the delay line circuit 7 and the P side is disconnected. Hereinafter, P and Q alternately perform their functions. D1, D2,
D3, D4, ... can be tapped at intervals of 2 × tdl. When the tap position selected in the P system is switched to the same tap position in the Q system, B _c , B _s
It is clear that each can be focused on the same focus position with the same value.

Considering the case where the difference is switched to the tap position of 2 × tdl, for example, when switching from D1 to D2, the difference in the phase control amount of D1 to D2 is π,
Using the minus side of the operation output of the multipliers M _C and M _S , B _c and B
_{If s} is also controlled by shifting π between D1 and D2, (D1
s (p), sin (p), D2 at cos (-π + p), sin
(-Π + p). It is possible to switch to a control state in which the same focus position is selected with the same values of B _c and B _s .

When the multiplication circuit group 4 has one system as described above, when switching is performed, taps and phases are controlled so that the same focus position control state is achieved in the P and Q systems. Also, at least 1 between the P and Q switching cycles.
It is also possible to use only the multiplication circuit element 501 to perform dynamic focus only for phase control.

In FIG. 7, because of the differential output, four signal lines are output for each element of the ultrasonic vibration element 1, but this requires signals of opposite polarities between taps shifted by π. Therefore, essentially, two types of signals may be considered. Also, the differential output is to eliminate the disturbance at the time of switching when the two systems are turned on at the same time. Therefore, if this disturbance is allowed (if the number of dynamic focus switching is large, the disturbance is small), the differential output is Since a single output can be obtained, in this case, it is sufficient to use two signal lines for each element of the ultrasonic vibration element 2.

The contacts (403-1 to 403) shown in FIGS.
-4, 502-1 to 502 -4) are conceptual ones,
It does not show the actual circuit configuration. It is to be noted that this contact point represents a contact point that connects a horizontal signal line and a vertical signal line in the drawing.

FIG. 8 shows the SW circuit groups 5-1 and 5-shown in FIG.
It is a figure explaining the element circuit of the circuit structure of 2. C0 ~ C3
Is, for example, four M _C (or M _S ) outputs 401 in FIG. Since the SW circuit group 5 is exactly the same on the P side and the Q side, only one side will be described. In this example, assuming that the analog switch M1 takes charge of the four output channels of the multiplication circuit element 4, the difference in the maximum required delay amount with respect to the number of channels is determined, so the required number of taps for the output of M1 is It's decided

This is set to 6 in this example. Then the second
Six analog switches M2 (M2-1 to M2-
6) You will need it. Then, a multiplication circuit element, for example, FIG.
If the maximum required number of taps in the delay line circuit 7 is 18 for one output of 401 (determined by the required maximum delay amount of the ultrasonic probe used), the output of M2 is 18/6 =
You will need three. If each element is connected as shown in Fig. 8, M2
-1 to M2-6, any of 6 consecutive T01 to T18
You can choose the tap. For example, M2-1 is T07, M2-2 to M2-
Choose up to 6 like T02 to T06.

However, for the M _C and M _S outputs of, for example, 401 in FIG. 6, the tap positions of the delay line circuit 7 cannot be selected so as to correspond to desired adjacent positions. As a matter of course, with this circuit, the above selection can be performed without any problem. That is, the inside of one element circuit in FIG. 8 may be limited to only the M _C (or M _S ) side. As a whole, n / 4 (for M _C ) + n / 4 (for M _S ) element circuits are required on the P side, and n / 4 (for M _C ') of this element circuit on the Q side.
+ N / 4 (for M _S ') pieces are required. In FIG. 7, on the P side,
The element circuit n / 2 (for M _C) + n / 2 (for M _S) number is required, the Q-side, the element circuit n / 2 (for M _C)
+ N / 2 (for M _S ) pieces are required.

Further, the tap interval of TO1 to T18 is 4 × tdl in the examples of FIGS. 6 and 7. Further, in the example of FIG. 6, the total number of taps is 2 × 18 on the P side and 2 × 18 on the Q side. In the example of FIG. 7, it is 4 × 18 on the P side and 4 × 18 on the Q side. And
The total number of these taps is the SW circuit group 5-1 (P
Side) is output as m = 36 (FIG. 6) or 72 (FIG. 7) signals from the SW circuit group 5-2 (Q side) shown in FIG. 1 to m = 36 (FIG. 6), or 72. (FIG. 7) Output as a book signal. Further, although M2-1 to M2-6 have one input, if a matrix switch is used, M2-1 to M2-for signals using the same tap groups T01 to T18 as shown in FIG.
6 can be commonly used for the number of input channels. In other words, it can handle M1 as many as the number of input channels.

Further, in FIG. 6, Dq1, Dq2, ...
It is also possible to use the same tap positions as Dp1, Dp2, ... On the Q side without using the taps of, and at this time, the number of taps from the delay line circuit 7 becomes half. Even in that case, the scale of the SW circuit group 5 does not change. The scale of the switching circuit group 6 does not change.

FIG. 10 is an explanatory diagram of the circuit configuration of the switching circuit group 6 in the case of FIG. M _{PI to} M _Pm and M _{QI to} M _Qm are analog multipliers or variable gain amplifiers, and are circuits for switching signals of m lines × 2 systems from the SW circuit groups 5-1 and 5-2. is there. For example, the SW circuit group 5-1 (P
The m signals from the (system) become the m input signals of the 701, and the m signals from the SW circuit group 5-2 (Q system) are 70 signals.
2 m input signals.

The signal of 701 is M_PI~ M_PmThe other
Communication input signal G_P(704) turns it on and off, and the 702 signal
Issue is M_QI~ M_QmThe other common input signal G_Q(705
 ) Turns it on and off. Figure 11 shows this ON / OFF tie.
Shows the ming chart, and when this is ON or OFF, G_P, G _QIs
Smoothly switch between tsw as shown by 704 and 705
And then t_poDuring this period, the P side is completely off. Also,
t_qoDuring the period, the Q side is completely off. And t_poof
In the meantime, the control value on the P side is rewritten, and t_qoQ side between
The control value of is rewritten. In the case of FIG. 10, the delay line circuit 7
For the number of taps d, m = d / 2. Also
G_P, G_QIs proportional to the gain of the multiplier, and G
_P+ G_Q= Make it constant. This shows in Figure 11.
Smoothly by reducing the amplitude fluctuation during tsw during switching.
It can be switched.

FIG. 12 is an explanatory diagram of the circuit configuration of the switching circuit group 6 in the case of FIG. M _{PI to} M _Pm and M _{QI to} M _Qm are analog multipliers or variable gain amplifiers, and circuits for switching signals of m lines × 2 systems from the SW circuit groups 5-1 and 5-2. Is. For example, m signals from the SW circuit group 5-1 (P system) shown in FIG. 1 become m input signals of 711, and m signals from the SW circuit group 5-2 (Q system) are , 712 m input signals. The signal of 711 is the other common input signal G _P (714) of M _{PI to} M _Pm.
ON, by which turned OFF, signal 712, the other common input signal ON by G _Q (715) of M _QI ~M _Qm, is OFF.

FIG. 13 is a timing chart of this ON / OFF.
Is displayed, and when this is ON or OFF, G_P, G_QAre shown at 714 and 715
To switch smoothly between tsw,_poBetween
Is completely OFF on the P side. Again t_qoQ side is perfect during
Is off. And t _poBetween the control values on the P side
Change and t_qoRewrite the control value on the Q side during
U.

At least 1 between P and Q switching cycles
It is also possible to perform dynamic focus only for phase control by using only the multiplication circuit element 501 shown in FIG. 7 at the times (A, B, C). In the case of FIG. 12, for the tap number d of the delay line circuit 7, m = d, and M _{PI to} M
The output of _Pm and M _QI ~M _Qm is output as the summed (e.g. addition by the constant current circuit) m of signal. (When P or Q is OFF, the OFF side is the signal current =
0) Further, it is assumed that G _P and G _Q are proportional to the gain of the multiplier, and that G _P + G _Q = constant so that they can be turned on and off smoothly.

FIG. 14 is a circuit diagram of the delay line circuit 7 shown in FIG. 802-1 to 802-d are 1to4 analog
This is a switch and selects the tap selection input section of the partial delay line circuit DL shown in FIG. Depending on the frequency of the probe, F1, F2, F3, and F4 are
Selected by analog switches 802-1 to 802-d. In addition, the tap with the smallest delay amount is 802-1,
The tap with the largest delay is connected to 802-d. And even if the probe frequency changes, the delay line circuit 7
Do not change the tap number d of. When the probe frequency becomes higher, the partial delay line circuit DL having the larger delay amount is gradually not used. The partial delay line circuit DL is
The DL terminals A and B are connected in series and output to the output terminal 804.

By the way, when the probe frequency becomes low,
If the number of taps output from the partial delay line circuit DL is reduced and the number of taps d of the delay line circuit 7 is kept constant, a large delay amount is required and the cost of the device increases. So, for example, 3.5MHz
So that the delay line circuit 7 has the maximum delay amount,
With z, the maximum delay amount is the same as 3.5MHz. That is, the number of taps becomes smaller than d at 2.5 MHz.
This method is also possible with this method.

FIG. 15 shows a partial delay line circuit DL used in 803-1 to 803-k of FIG. 901 is an input part of each tap for probe frequencies of 2.5 MHz, 3.5 MHz, 5.0 MHz and 7.5 MHz, and 902 is a constant current amplifier, which is an input part for connecting the partial delay line circuits DL to each other. Has become. The 903 is also a constant current amplifier, with F1 and F on the input side.
There is a resistor for adding the current from the signals from 2, F3 and F4.

Reference numeral 904 denotes a constant current amplifier, which serves as an output unit for connecting the partial delay line circuits DL to each other. 902,
904 is a variable gain amplifier that separates the unused partial delay line circuit DL. Also, 904 is a delay line 906 on the input side.
Has a resistor for terminating the. 905 is a terminating resistor on the input side, 906 is a delay line, for example, tde = 18nsec
The delay element of is composed of 12 elements. For 7.5MHz, tapping every 2 × tde (36nsec) gives 6 taps. (F4) For 5.0MHz, tapping every 3 × tde (54nsec) gives 4 taps. (F3) For 3.5MHz, tapping every 4 × tde (72nsec) yields 3 taps. (F2) For 2.5MHz, if you tap every 6 × tde (108nsec), you get 2 taps. (F1) Further, the delay line 906 may be further divided into, for example, two parts, and the part between them may be connected by a constant current amplifier. Such division is advantageous for frequency characteristics and reflection inside the partial delay line circuit DL.

As is clear from the above description, the present invention can reduce the influence of attenuation by the living body by suppressing the focus control amount by the phase control of the carrier wave .

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a diagram showing a principle of ultrasonic diagnosis.

FIG. 3 is an explanatory diagram of phases.

FIG. 4 is a diagram illustrating a function of a multiplication circuit.

FIG. 5 is a diagram showing a specific example of performing phase control from −π to + π.

FIG. 6 is a diagram showing an embodiment in the case where the multiplication circuit group has two systems.

FIG. 7 is a diagram showing an embodiment in which the multiplication circuit group is one system.

FIG. 8 is a diagram showing circuit components of a SW circuit group.

FIG. 9 is a schematic diagram of a matrix switch in FIG.
It is a figure which shows the case where it is set as four input rather than input.

10 is a diagram showing a switching circuit group in the case of FIG. 6;

11 is a timing chart of FIG.

12 is a diagram showing a switching circuit group in the case of FIG. 7. FIG.

13 is a timing chart of FIG.

FIG. 14 is a configuration diagram of a delay line circuit.

FIG. 15 is a partial delay line circuit configuration diagram.

[Explanation of symbols]

 1 transmitter circuit (control circuit of transmitter driver circuit) 2 2-1, 2-2, ..., 2-n ultrasonic transducer 3 3-1, 3-2, ..., 3-n transmitter / receiver circuit group 4 multiplication Circuit group 5 5-1 and 5-2 SW circuit group 6 Switching circuit group 7 Delay line circuit 8 Log amplifier 9 Display

Claims (4)

(57) [Claims] 1. An ultrasonic probe composed of ultrasonic transducers (2) arranged in a predetermined shape and an ultrasonic transducer corresponding to a desired transmission driver of a transmission / reception circuit (3) are selected. From 2), a transmission circuit (1) that outputs an ultrasonic pulse to the subject and outputs a control signal for emitting an ultrasonic pulse focused at a desired depth position of the subject, and the ultrasonic pulse Focusing on a desired depth position by receiving a reflected wave from the subject from the ultrasonic vibration element (2), performing delay time control and phase control corresponding to each received signal, and adding them. An ultrasonic diagnostic apparatus comprising a receiving circuit system (3, 4, 5, 6, 7) capable of performing the above, and display means (8, 9) for displaying the added received signal as an image. System (3,4,5,6,7) is above Wave
A multiplying circuit (4) having as a constituent element a circuit having an amplifier capable of varying at least two gains per element of the vibrating element (2) and controlling the allocation of gains of these two amplifiers; , A switch circuit section (5, 6) for switching and connecting each amplifier output corresponding to the output of each ultrasonic vibrating element (2) of this multiplication circuit (4) to a desired output terminal, and this switch circuit section ( 5 and 6) having a tap corresponding to the output terminal and having a delay line circuit (7) for changing the delay amount of the input signal depending on the position of the tap, which is a constituent element of the multiplication circuit (4) 2 The two output terminals of the amplifier whose number of gains is variable are switched to an arbitrary pair within a set formed by forming a pair of appropriate two taps of the delay line circuit (7) and selecting an appropriate interval. , That you can connect Ultrasonic diagnostic apparatus according to claim. 2. The delay circuit, wherein the multiplication circuit (4) comprises a first circuit and a second circuit each having two variable gain amplifiers per one element of the ultrasonic vibration element (2). The first circuit includes a first set formed by selecting appropriate two taps of the circuit (7) as a pair and selecting the pair at appropriate intervals, and a second set consisting of a pair between the appropriate intervals. The two output terminals of the two variable gain amplifiers can be switched and connected to any pair of the first set, and the two output terminals of the two variable gain amplifiers of the second circuit can be connected to the second set. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus can be switched and connected to any pair. 3. The multiplying circuit (4) is configured to apply the ultrasonic vibration.
Two variable gain amplifiers per moving element (2)
From the first variable gain amplifier,
1 output and a second output of negative polarity, and the second variable gain
・ From the amplifier, the third output of positive polarity and the fourth output of negative polarity are
And the tap interval of the delay line circuit (7) is
Within the change range of the carrier frequency of the ultrasonic signal due to the attenuation at
The delay line circuit is a quarter of a specific frequency cycle,
The adjacent two taps in (7) are paired and the delay amount is set in this order.
When the extended tap pairs are numbered, the delay line circuit (7)
Two differential taps on one side of the two differential outputs
Two polar outputs are connected and the other two taps of even-numbered pairs
Make sure that the two outputs with the opposite polarity are connected, and
When connecting, the gain control of two variable gain amplifiers is cos
When expressed by (p), sin (p), 2 at the time of even number connection
Gain control of the variable gain amplifier is cos (−π + p), si
3. The method according to claim 2, wherein n (−π + p).
The ultrasonic diagnostic apparatus described. 4. A delay line constituting the delay line circuit (7)
The delay time between taps of the probe frequency is 2.5MHz
, 3.5MHZ, 5.0MHZ, 7.5MHZ
And the ratio becomes 6: 4: 3: 2, and the 7.5 MHz probe is used.
All probes within 12 taps of delay taps for
The feature is that an integer number of frequency taps are entered.
The ultrasonic diagnostic apparatus according to any one of claims 1 to 3.