JPH04339253A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To constitute a delay-line circuit of one system and to make the same hard to receive the effect of the attenuation of a living body. CONSTITUTION:The receiving circuit of an ultrasonic diagnostic apparatus is constituted of a multiplier circuit group 4 making the gains of the outputs from ultrasonic vibration elements 2 variable, first and second switch circuits 5-1, 5-2 changing over and connecting the outputs corresponding to the outputs of the ultrasonic vibration elements 2 of the multiplier circuit group 4 to desired output terminals, a delay-line circuit 7 having the taps corresponding to the output terminals of the first and second switch circuits 5-1, 5-2 and changing the delay quantity of an input signal according to the tap positions and a change-over circuit group 6 changing over the taps of the delay-line circuit 7 and the corresponding output terminals of the first or second switch circuits 5-1, 5-2 to connect them and reduced in noise at the time of change-over.

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

[Prior Art] Ultrasonic imaging devices are used to detect flaws and defects in materials and structures by utilizing the reflection and transmission of ultrasonic waves, but they are also widely used in the medical field as diagnostic materials. It is used as.

[0003] The principle of ultrasonic examination or diagnosis will now be explained using FIG. 2. When ultrasonic waves are transmitted to the subject from each of the transducers arranged in an array, that is, the ultrasonic transducer elements, the ultrasonic waves that hit point D1 inside the subject are reflected and return to the transducers again. At this time, since the distance between D1 and each vibrator is different, the time for the reflected wave to return varies depending on the position of the vibrator.

[0004] Therefore, a large delay is given to the vibrator (the one in the center of the halftone dotted vibrator in the figure) that returns quickly.
A delay line that provides a small delay is passed through the vibrator that returns late, and the amount of delay is controlled so that the reflected waves of each vibrator arrive at the addition point at the same time. The waveform surrounded by the dotted line closer to the delay line shows the waveform after the delay processing has been performed in this manner. The result of adding these waveforms is the smaller waveform enclosed by the dotted line. When this waveform is converted to brightness and displayed, the inside of the target object is displayed as shown on the monitor. The dotted arrow on the monitor corresponds to the solid arrow within the object, and this line is called a scanning line. Note that the dynamic focus function is a function that momentarily changes the focal position on the scanning line during reception. Here, we gave an example of focusing using only a delay line, but by replacing part of the delay line with a phase shifter,
Focusing can also be achieved by a combination of phase control and delay time control.

[0005]

[Problem to be solved by the invention] JP-A-56-1122
Publication No. 34 discloses a technique using a two-system tap-switching phased array, but it requires two expensive delay line groups and the entire phased array has a long delay time. , it is difficult to shorten the switching cycle. The reason why two delay line groups are required is that the tap positions of the delay lines are switched in order to change the amount of delay, which generates noise. To prevent this, two delay line groups are provided, and while one delay line group is in use, the taps of the other delay line group are switched. Furthermore, a phased array is a delay system in which an electronic delay is applied to an array of vibrators so that the focus can be set freely.

[0006] Also, USP 4140022 discloses a technology using a mixer, but this only controls the phase of the carrier wave of the received signal. With a probe with a large aperture that changes by nearly three times, if the center frequency of the ultrasound signal changes due to attenuation in the living body,
Beam degradation occurs outside of the vicinity of the depth position where dynamic focus is optimal. In order to prevent this deterioration, it is necessary to divide the depth direction into several stages, perform optimal dynamic focus control for each depth, and combine the received signal groups to create a single scanning line. Not,
In order to obtain one tomographic image, a signal amount necessary to obtain several tomographic images is required, and the real-time performance, which is the original purpose of dynamic focusing, is sacrificed. Note that beam deterioration cannot be prevented by dividing the beam into two or three stages in the depth direction.

The present invention has been made in view of the above-mentioned problems, and aims to provide an ultrasonic diagnostic apparatus that uses only one system of expensive delay line circuits and is less susceptible to the effects of biological attenuation. do.

[0008]

[Means for Solving the Problems] FIG. 1 is a diagram showing the principle of the present invention. In the figure, reference numeral 2 denotes ultrasonic transducer elements arranged in a predetermined shape, and numeral 1 selects a desired transmission driver of the transmitting/receiving circuit 3, and transmits ultrasonic pulses to the subject using the ultrasonic transducer element 2 corresponding to the transmission driver. A transmitting circuit 3, 4, 5, 6, and 7 outputs a control signal for emitting an ultrasonic pulse focused at a desired depth position of the subject; This is a receiving circuit that receives reflected waves from a desired one of the ultrasonic transducer elements 2, performs control and phase control to generate delay times corresponding to each received signal, and then adds them. 8 and 9 are display means for displaying the added received signals as images. The receiving circuits 3, 4, 5, 6, and 7 include a receiving amplifier of a transmitting/receiving circuit 3 consisting of a transmitting driver and a receiving amplifier, and at least two gain-variable amplifiers per element of the ultrasonic vibration element 2. A multiplication circuit 4 whose components include a circuit capable of controlling gain allocation of each amplifier, and an output corresponding to the output of each of the ultrasonic transducer elements 2 of the multiplication circuit 4 as a desired output. A first switch circuit 5-1 and a second switch circuit 5 that switch and connect to the terminals.
-2, and taps corresponding to the output terminals of the first switch circuit 5-1 and the second switch circuit 5-2,
A delay line circuit 7 that changes the amount of delay of an input signal depending on the position of this tap, and a tap of this delay line circuit 7 and the first
Switch circuit 5-1 or the second switch circuit 5-2
The circuit includes a switching circuit 6 that generates little noise during switching to switch and connect the corresponding output terminals, and the first switch circuit 5-1 or the second switch circuit 5-2 is connected to the delay line circuit 7. , an operation is performed to switch and connect the output corresponding to the output of each of the ultrasonic transducer elements 2 of the unconnected switch circuit to the desired output terminal, and the two components of the multiplication circuit are connected. The two output terminals of the amplifier with variable gain are paired with appropriate two taps of the delay line circuit 7, and this pair can be switched and connected to any pair of the configured pairs by selecting an appropriate interval. Make it.

Further, the multiplication circuit 4 includes a first circuit and a second circuit, both of which have two variable gain amplifiers per element of the ultrasonic transducer 2, and the delay line circuit 7 A first set is made up of pairs of two taps selected at appropriate intervals, and a second set is made up of pairs between the appropriate intervals, and the two variable gains of the first circuit are - 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.・Enable connection.

Further, the multiplication circuit 4 has two variable gain amplifiers per element of the ultrasonic transducer 2, and a first variable gain amplifier of one of the two Switch circuit 5-1 and second switch circuit 5-2
A signal is supplied to the first switch circuit 5-1 and the second switch circuit 5-2 from the other second variable gain amplifier independently of the signal line from the first variable gain amplifier. supply.

Further, the first variable gain amplifier outputs a first output of positive polarity and a second output of negative polarity.
A third output with positive polarity and a fourth output with negative polarity are output from the variable gain amplifier, and the tap interval of the delay line circuit 7 is specified within the range of change in the carrier frequency of the ultrasound signal due to attenuation in the living body. It corresponds to 1/4 period of the frequency period, and when two adjacent taps of the delay line circuit 7 are paired and the delay amount tap pairs are numbered in order of delay amount, the first switch circuit 5-1 or In either switch system of the second switch circuit 5-2, two outputs of one polarity of the two differential outputs are connected to two taps of the odd-numbered pair of the delay line circuit 7, and two outputs of one polarity of the two differential outputs are connected to the two taps of the odd-numbered pair of the delay line circuit 7. The two outputs with the other polarity are connected to the two taps of
p), the gain control of the two variable gain amplifiers is cos(-π+p), si when connected as an even number.
n(-π+p).

[0012] Further, the delay time between the taps of the delay line constituting the delay line circuit 7 is set at a probe frequency of 2.5 MHz.
,3.5MHz ,5.0MHz ,7.5MHz
On the other hand, the ratio is 6:4:3:2, so that an integer number of taps for all probe frequencies are included between the 12 tap intervals of the delay taps for the 7.5 MHz probe.

[0013]

[Function] First, the function of phase control and delay line will be explained. It is assumed that the received signal for one element of the ultrasonic transducer element 2 is expressed by the following equation. u(t)=a(t) sin (ωt+ψ) (1
) Figure 3(a) shows equation (1), where the amplitude a(t)
represents the envelope component shown by the broken line. Here ω is the angular frequency,
ψ represents the phase angle. A signal delayed by t0 time from equation (1) is expressed by the following equation. u(t-t0)=a(t-t0) sin (ω(t-t
0)+ψ) (2) FIG. 3(b) represents equation (2). t0 is referred to as delay amount t0, and is realized by the delay line circuit 7. In this case, both envelope component a(t) and carrier wave are t0
Time will be delayed. Next, if only the carrier wave of the signal is delayed by time t0, it is expressed by the following equation. u'(t-t0)=a(t) sin (ω(t-t0)
+ψ) (3) Figure 3(c) represents equation (3). The envelope component is the same as in figure (a), and the carrier wave is in the same phase as in figure (b). The multiplication circuit 4 that performs phase control realizes this effect.

In the phasing process expressed by equation (2), since the waveform itself can be moved by t0, the signals from each vibrating element can be perfectly matched, so a great focusing effect can be obtained; however, (3) Since the phasing process expressed by the formula does not delay the envelope component, it is not possible to match the signals from each vibrator. However, a close match can be achieved. However, the phasing method using equation (2) is (3)
The device becomes more complicated and expensive than when using a formula. Therefore, large phasing processing is performed in steps by the delay line circuit 7 that implements equation (2), and small phasing processing within the step width is performed by multiplication circuit 4 that implements equation (3).

As described above, the phase of the carrier wave is controlled by the multiplication circuit 4, and while the change in the amount of delay is small (for example, when λ is the wavelength of the ultrasonic signal, less than ±0.5λ), the carrier wave can be controlled by this phase control alone. Focuses the sound beam. When the change in the amount of delay becomes large, the tap of the delay line circuit 7 is changed by controlling the phase of the multiplier circuit 4, changing the setting of the switch circuit 5, and switching the switch circuit 5 by the switching circuit 6, and then changing the tap of the delay line circuit 7 by controlling the phase of the carrier wave. The focus control amount should not be too large, for example, less than ±0.5λ. By suppressing the focus control amount by carrier wave phase control in this manner, the influence of attenuation due to the living body can be reduced.

Next, in order to use only one system of delay line circuits, the following procedure is performed. Even if there is only one multiplication circuit 4,
Although it is possible to use two systems, (in the case of one system, the circuit must be such that no noise is generated when the control amount is changed.) The switch circuit 5 is designed to prevent noise when switching the switch contacts. There will be two systems. The unused switch circuit 5 is separated from the delay line circuit 7 by a switching circuit 6. Then, while the switch circuit 5 is disconnected, the next set value is set in the disconnected switch circuit 5. Then, at the next switching timing,
The switching circuit 6 is switched, the system of the switch circuit 5 with the new setting value is connected to the delay line circuit 7, and the system of the switch circuit 5 that has been connected is disconnected from the delay line circuit 7. After that, the same thing is repeated alternately.

Note that the multiplier circuit 4 changes the control amount when the switching circuit 6 switches when there is one system, and when it is disconnected when there are two systems, it changes the control amount of the disconnected system. conduct. In this way, since switching is performed before the delay line circuit 7, only one delay line circuit 7 is required.

The switch circuit 5, which requires a huge number of contacts, has two
An ordinary inexpensive analog switch that has a system and generates switching noise can be used, and an expensive switching circuit 6 that does not generate noise is used only at the connection part between a delay line circuit 7 and a switch circuit 5. With the circuit system of this configuration, the circuit parts of two systems and the circuit parts that increase in number can be integrated into ICs (using ASIC, etc.), and the delay line circuit parts that cannot be integrated into ICs can be integrated into one system.

[0019]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. The basic configuration of this embodiment is the same as the principle diagram shown in FIG. 1, so a detailed explanation of FIG. 1 and the constituent parts of FIG. 1 will be explained using the drawings. In FIG. 1, reference numeral 1 denotes a transmitting circuit that generates a signal for controlling a transmitting driver circuit. 2 is an array of ultrasonic vibration elements, 2-1 to 2-n
are individual ultrasonic vibration elements. 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 a noise circuit. 7 is a delay line circuit, 8 is a log amplifier, and 9 is a display device.

The transmitting circuit 1 sends a control signal for emitting an ultrasonic pulse focused on a desired depth position of the subject to a desired transmitting driver circuit of the transmitting/receiving circuits 3-1 to 3-n. , drives the ultrasonic vibration element 2 corresponding to the transmission driver circuit to emit a transmission pulse to the subject. The reflected waves of this transmitted pulse from the subject are received by each of the ultrasonic transducer elements 2-1 to 2-n, and passed through the receiving amplifier of the transmitter/receiver circuit 3, so that only the signal from the desired transducer element 2 has an appropriate gain. For example, the reception gain at the aperture position of the reception aperture constituted by the selected vibrating element 2 is apodized in the shape of a Gaussian curve.
zing) and guided to the multiplication circuit group 4. In addition,
Apodizing in this case is a process in which the gain at the time of reception or the gain at the time of transmission is made smaller as the vibrating element 2 is closer to both ends of the aperture.

[0021] Note that the apodization of the received signal may be carried out by changing the gain of the receiving amplifier of the transmitting/receiving circuit 3,
It is also possible to set it using the multiplication circuit group 4. Furthermore, for unnecessary received signals, apodizing may be set to 0. Also, during dynamic focusing, the aperture is gradually enlarged depending on the depth to which the received signal returns.
This can be done 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
Two types of gains or signals differing only in gain and polarity are output per element, and SW circuit group 5 and switching circuit group 6
are connected to appropriate adjacent taps of the delay line circuit 7 through the multiplication circuit group 4, and the phase of the carrier wave of the received signal is controlled to a desired phase by assigning the gains of these two types of signal lines performed by the multiplication circuit group 4. . However, if there are 2 systems from multiplication circuit group 4, 2 types x 2 per element of ultrasonic vibration element 2
System signals are output from the multiplication circuit group 4.

The switching circuit group 6 includes SW circuit groups 5-1,
Select one of the two routes in 5-2 and select the SW
The tap selection of the delay line circuit 7 is determined by the circuit group 5,
The received signal is focused, and the output signal of the delay line circuit 7 is logarithmically converted by a log amplifier 8, and sent to a display 9 to be displayed as an image.

In addition, the next set value is set for the circuit system that is not selected, and at the next dynamic focus timing, the switching circuit 6 switches noiselessly, and the focus at the next depth position is selected. . By performing dynamic focusing alternately in the two systems, it is possible to switch several dozen times in the depth direction on the scanning line.

Next, the multiplication circuit will be explained in detail with reference to FIG. FIG. 4 explains the function of the multiplication circuit group 4, and is a configuration diagram of each element of the ultrasonic vibration element 2. FIG. 2 is a configuration diagram per element when the multiplication circuit group 4 shown in FIG. 1 is one system or only one side of two systems. Also, to simplify the explanation, the SW circuit group 5 and the switching circuit group 6 in FIG.
are omitted, and the portions connected to selected adjacent tap positions Ti and Ti+1 of the delay line circuit 7 are shown.

A is any one of the transmitting/receiving circuits 3-1 to 3-n.
This is the output signal of the receiving section for the circuit, and by the two multipliers MC and MS that take this signal as one input, Cc = A×
The components of the multiplication circuit group 4 are circuits that generate gains such that Bc, Cs=A×Bs, or two types of signals that differ only in gain and polarity. Generally, the received signal A is approximately A=a (t − tdj ) sin (ω・t
−Φdj). Here, a (t − tdj
) is the amplitude modulation term, tdj is the delay time due to the path length of the received signal received by each transducer 2, and Φdj is the phase shift of the carrier wave, which generally has a different value for each ultrasonic transducer 2. . Further, t is time, and ω is the angular frequency of the received signal carrier.

Further, let tdl be the tap interval between taps Ti+1 and Ti of the delay line circuit 7, and let tdi be the total delay time obtained by integrating the amount of delay from Ti to tap To, which is the minimum delay time. Output signal E of the delay line circuit 7 based on only two signals inputted to Ti+1 and Ti in FIG.
When Bc = a1 and Bs = a2, dlo is expressed as follows. Here, a1 and a2 are control signals for setting the gains of the multipliers MC and MS.

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=
If we set t −Φdj/ω−tdi, Edlo=a1・a (τ1) sin (ω・τ2)+
a2・a (τ1−tdl ) sin (ω・(τ2−
tdl))

In addition, the amplitude modulation term a (t
) has only lower frequency components than the carrier wave. Also, since the tap interval tdl is set to 1/4 or less of the carrier wave period Tp, a (τ1)≒a (τ1−tdl)
may be used as Therefore, multiply as follows. Edlo≒a (τ1) [a1・sin (ω・τ2)
+a2・sin (ω・(τ2−tdl ))]

Furthermore, when p is an arbitrary phase, a1, a2
Therefore, Edlo=a (τ1)・sin (ω・τ2−
p) In other words, in order to obtain a signal whose phase is controlled by p, if we set Φdl=ω・tdl, a1=cos (p)
−sin (p)・cos (Φdl)/sin (Φ
dl), a2 = sin (p)/sin (Φdl). Note that the ultrasonic signal is attenuated in the living body and the value of ω changes, but Φdl
can be determined at one point within the domain of ω. For a 3.5 MHz probe, a1 and a2 may be calculated by taking ω for 3.5 MHz, or by taking a slightly lower value of ω in consideration of attenuation.

When the multiplication circuit group 4 performs up to apodizing, if the apodizing value of the ultrasonic transducer is apj, then a1=apj ・(cos (p)−sin (p)・
cos (Φdl)/sin (Φdl)) a2=apj ・sin (p)/sin (Φdl)
What is necessary is to set a1 and a2 so that.

When interpolation is used only between taps Ti+1 and Ti, good interpolation results can be obtained for any tap interval tdl such that Φdl≦π/2, but it is not possible to extrapolate widely outside the tap interval. When performing carrier wave phase control in the range of -π to +π, for example, it is better to set Φdl=π/2.

If only interpolation is used between the taps Ti+1 and Ti and tdl is also made small, the influence of the drop in the carrier frequency due to the attenuation of the ultrasound signal by the living body will be smaller; As the number increases, S
The W circuit group 5 and the switching circuit group 6 are also increased. In this embodiment, a case where phase control is performed in the range of -π to +π will be explained.

FIG. 5 shows a specific example of phase control in the range of -π to +π. If we choose Φdl=π/2, a1=
cos (p), a2=sin (p). λ/1
If phase control is performed in increments of 6, 16 types of control values are required, but since a1 and a2 are periodic functions,
The entire range can be controlled using eight types of control values a, b, c, d, e, f, g, and h in FIG. This control value is 8 D/A
It can be made with a transducer and can be used commonly for all ultrasonic vibration elements 2.

[0035] Also, if 4 bits of control signals B0 to B3 are used and SI and SO are created by EOR of 301,
The control signals Bs and Bc in FIG. 4 are obtained by the 8to1 analog switches 302 and 303. Note that Ad is 0 to 0 of the analog switches 302 and 303.
This is a 3-bit control address for selecting 8 contacts of 7.

In this way, the selected tap T of the delay line circuit 7 is controlled by the 4-bit control signals B0 to B3.
It is possible to control the phase of the carrier wave from -π to +π from the center of i, Ti+1 (shaded area). Also, it is naturally possible to configure the circuit with two D/A converters instead of the analog switches 302 and 303. In this case, if a decoding section is provided in the control input system of the D/A converter,
Apodizing is also facilitated.

FIG. 6 shows an embodiment in which there are two systems from the multiplication circuit group 4, and each ultrasonic vibration element 2 has two systems.
There are multiplication circuit elements 401 and 402 of the system. The multiplication circuit elements 401 and 402 have the same functions as those described in FIGS. 4 and 5. Note that the switching circuit group 6 in FIG. 1 is omitted to simplify the explanation. A is a received signal output from the transmitting/receiving circuit 3. Although FIG. 6 only shows one element of the ultrasonic vibration element 2, the multiplication circuit element 4
01 and 402 are required for the number of elements (n shown in FIG. 1).

[0038] Also, each element 2 to 403 or 404
(Although not shown in 403 and 404, contacts for receiving signals from other ultrasonic transducer elements 2 are also included.) The signal sent to the delay line circuit 7 is , is added within the delay line circuit 7. Here, 403 and 404 are SW circuit groups 5-1 and 5-2
This is a part of the diagram.

When the multiplier circuit elements 401 and 403 (system P) are performing the focus action, the multiplier circuit elements 402 and 404 (system Q) are separated from the delay line circuit 7 (not shown), and the next The control value of is set in the multiplication circuit elements 402 and 404. In the multiplication circuit element 401, per element of the ultrasonic vibration element 2,
Two types of gains or signals differing only in gain and polarity are output, and one set of two contacts in the SW circuit group 403, for example, 403-3 and 403-4, are selected, and the appropriate signals in the delay line circuit 7 are output. Adjacent taps (403-3 and
403-4, it is connected to 2 taps of Dp2) (by selecting the tap, a large delay control of an integer multiple of 2 x tdl is performed), 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 thing as described above is performed for the other ultrasonic transducer elements 2, and each received signal is added on the delay line circuit 7 and focused on a 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. Thereafter, P and Q perform their functions alternately. Dp1
, Dp2 ,..., Dq1 , Dq2 ,... are 4
It is sufficient to issue taps at intervals of ×tdl. Also, Dp1
, Dp2,... and Dq1, Dq2,... are the same tap position (for example, only the tap positions of Dp1, Dp2,... are used), the above is possible, but P~ When switching between Q, for example, Dp1 at P
If Dp2 is selected in Q when Dp2 is selected, a difference in delay amount of 4×tdl will occur at the time of switching. D
p1, Dp2,... and Dq1, Dq2,...
By shifting 2×tdl, the difference in the switching delay amount can be reduced to 2×tdl or less. however,
Although the tap at the left end of Dp1 cannot be covered within the phase control range from Dq1 to π, 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 is one system, and there is one system of multiplication circuit elements 501 for each ultrasonic vibration element 2. Multiplication circuit element 5
01 has the same function as that explained in FIGS. 4 and 5. Since the multiplication circuit element 501 is shared by the P system and the Q system, noise becomes a problem when changing the control values of Bc and Bs. Therefore, the low bus filter Fc5
01 -1, Fs501-2 is inserted to reduce noise when changing control values. Bc, Bs to MC
, MS do not include high-frequency carrier waves, and can be filtered with a low frequency commensurate with the switching period (several microseconds). Further, in order to simplify the explanation, the switching circuit group 6 shown in FIG. 1 is omitted.

A is a received signal output from the transmitting/receiving circuit. Although FIG. 7 shows only one element of the ultrasonic vibration element 2, the number of multiplication circuit elements 501 corresponding to the number of elements (n shown in FIG. 1) is required. Further, from each element 2 via 502 (or 503) (although not shown in 502 and 503, contacts for receiving signals from other ultrasonic transducer elements 2 are also included). , the signals sent to the delay line circuit 7 are added within the delay line circuit 7. Note that 502 and 503 are SW circuit groups 5-1 and 5-5.
-2 is partially illustrated.

When the system P performs the focusing action, the system Q is separated from the delay line circuit 7 (
(Figure omitted), the next control value is set to 503. In the multiplication circuit element 501, two types of gain or signals differing only in gain and polarity are created for each element of the ultrasonic vibration element 2, and the output is output as a differential output,
A set of two contacts in the W circuit group 502, for example 502 -
3 and 502-4 are selected, and are connected to appropriate adjacent taps of the delay line circuit 7 (in the case of 502-3 and 502-4, two taps of D2). tdl is performed.) By allocating the gains of these two types of signal lines (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 described above is performed for the other ultrasonic transducer elements 2, and each received signal is added on the delay line circuit 7 and focused on a 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. Thereafter, P and Q perform their functions alternately. D1, D
2, D3, D4, . . ., taps should be output 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, it is obvious that Bc and Bs have the same value and focus can be applied to the same focus position.

When switching to a tap position with a difference of 2×tdl, for example, when switching from D1 to D2, the difference between the phase control amounts of D1 and D2 is π, so the multipliers MC, If we use the negative side of the operating output of MS and shift the control of Bc and Bs by π between D1 and D2, we can obtain cos (p), sin (p
), cos (-π+p), sin (-π+p) in D2
). ) It is possible to switch to a control state in which the values of Bc and Bs are the same and the same focus position is selected.

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

In FIG. 7, four signal lines are output per ultrasonic transducer element 1 for differential output, but this requires signals with opposite polarity between the taps shifted by π. Therefore, they can essentially be considered as two types of signals. Also,
The purpose of differential output is to eliminate disturbances when switching when two systems are ON at the same time, so if this disturbance is allowed (the disturbance will be small if dynamic focus is switched many times), differential output can be converted to a single output. Therefore, in this case, exactly two signal lines are required for each ultrasonic transducer element 2.

Contact points (403-1 to 403-1) shown in FIGS. 6 and 7
403-4, 502-1 to 502-4) are conceptual and do not indicate actual circuit configurations. Note 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.
FIG. 2 is a diagram illustrating element circuits of circuit configuration No.-2. C0～
C3 is, for example, 401 MC (or MS
) 4 outputs. Since the SW circuit group 5 is completely the same on the P side and the Q side, only one side will be explained. In this example, if analog switch M1 is to handle four channels of the output of multiplier circuit element 4, the difference in the maximum amount of delay required for the number of channels is determined, so the required number of taps for the output of M1 is Kimimaru.

[0050] This is set to 6 in this example. Then the second
There are six analog switches M2 (M2-1 to M
2-6) It becomes necessary. And the multiplication circuit element, for example,
If the required maximum number of taps in the delay line circuit 7 is 18 for one output of 401 in FIG. 6 (determined by the required maximum delay amount of the ultrasound probe used), the output of M2 is 18/6= Three pieces are required. If each element is connected as shown in Figure 8, T01 to T18 will be connected by M2-1 to M2-6.
You can select any 6 consecutive taps. For example, M2
-1 is T07, M2-2 to M2-6 are T02
~T06.

However, for the MC and MS outputs of, for example, 401 in FIG. 6, the tap positions of the delay line circuit 7 are as follows:
It goes without saying that the selections should be made in correspondence so that the desired adjacent positions are achieved, and the above selection can be made without any problem with this circuit. In other words, M
It is only necessary to limit it to the C (or MS) side. Overall, on the P side, this element circuit is n/4 (for MC) + n/4
(for MS), and this element circuit is n on the Q side.
/4 (for MC') + n/4 (for MS') pieces are required. In Figure 7, n/2 (for MC) + n/2 (for MS) element circuits are required on the P side, and n/2 (for MC) + n/2 (for MS) element circuits are required on the Q side. ) pieces are required.

Further, the tap interval between TO1 to T18 is 4×tdl in the examples of FIGS. 6 and 7. Also, in the example of Figure 6, the total number of taps is 2 x 18 on the P side and 2 x 1 on the Q side.
It becomes 8. In the example in Figure 7, 4×18 on the P side and 4× on the Q side.
It will be 18. Then, the total number of taps is output as m=36 (FIG. 6) or 72 (FIG. 7) signals from the SW circuit group 5-1 (P side) shown in FIG. The circuit group 5-2 (Q side) outputs m=36 (FIG. 6) or 72 (FIG. 7) signals. Also, M2-
1 to M2-6 have one input, but if a matrix switch is used, the same tap group T01 to M2-6 can be input as shown in FIG.
For signals using T18, M2-1 to M2-6 can be used in common as many as the number of input channels. In other words,
It can handle the same number of M1 as the number of input channels.

In addition, in FIG. 6, Dq1, Dq2
,... on the Q side without using the taps Dp1, D
It is also possible to use the same tap position as p2,...,
At this time, the number of taps from the delay line circuit 7 is halved. Even in that case, the scale of the SW circuit group 5 remains unchanged. The scale of the switching circuit group 6 also remains unchanged.

FIG. 10 is an explanatory diagram of the circuit configuration of the switching circuit group 6 in the case of FIG. MPI~MPm, MQI~M
Qm is an analog multiplier or a variable gain amplifier, and is a circuit for switching m×2 signals from the SW circuit groups 5-1 and 5-2. For example, m signals from SW circuit group 5-1 (P system) become m input signals of 701, and m signals from SW circuit group 5-2 (Q system) become m input signals of 702. This becomes the input signal for the book.

The signal 701 is turned on and off by the other common input signal GP (704) of MPI to MPm.
FF, and the signal 702 is turned on and off by the other common input signal GQ (705) of MQI to MQm.
FF is done. FIG. 11 shows a timing chart of this ON and OFF, and when this ON and OFF, GP, G
As shown at 704 and 705, Q switches smoothly during tsw, and the P side is completely OFF during tpo. Also, during tqo, the Q side is completely O.
FF is doing it. Then, the control value on the P side is rewritten during tpo, and the control value on the Q side is rewritten during tqo. In the case of FIG. 10, m=d/2 for the number of taps d of the delay line circuit 7. It is also assumed that GP and GQ are proportional to the gain of the multiplier, and GP + GQ =
Make it constant. As a result, even during the switching time tsw shown in FIG. 11, amplitude fluctuations can be reduced and switching can be performed smoothly.

FIG. 12 is an explanatory diagram of the circuit configuration of the switching circuit group 6 in the case of FIG. MPI~MPm, MQI~M
Qm is an analog multiplier or a variable gain amplifier, and is a circuit for switching m×2 signals from the SW circuit groups 5-1 and 5-2. For example, Figure 1
The m signals from the SW circuit group 5-1 (P system) shown in FIG.
The m signals from (Q system) become m input signals of 712. The signal 711 is turned on and off by the other common input signal GP (714) of MPI to MPm.
F and the signal 712 is turned on and off by the other common input signal GQ (715) of MQI to MQm.
F will be done.

FIG. 13 shows a timing chart of this ON and OFF, and during this ON and OFF, GP and GQ are smoothly switched during tsw as shown at 714 and 715, and during tpo, the P side is completely off
are doing. Also, during tqo, the Q side is completely OFF. Then, the control value on the P side is rewritten during tpo, and the control value on the Q side is rewritten during tqo.

At least 1 during the switching period of P and Q
times (A, B, C), the multiplication circuit element 501 shown in FIG.
It is also possible to perform dynamic focusing using only phase control. In the case of FIG. 12, m=d for the number of taps d of the delay line circuit 7, and M
The outputs of PI to MPm and MQI to MQm are added (eg, added by a constant current circuit) and output as m signals. (When P or Q is OFF, the signal current on the OFF side is 0.) Also, assume that GP and GQ are proportional to the gain of the multiplier, and GP + GQ = constant, so that they can be turned ON and OFF smoothly. do it like this.

FIG. 14 is a circuit diagram of the delay line circuit 7 shown in FIG. 1. 802-1 to 802-d are 1to4
This analog switch selects the tap selection input section of the partial delay line circuit DL shown in FIG. F1, F
2, F3, F4 are either 1 depending on the probe frequency.
For example, the input part of F3 is 802 -1 to 802
-d analog switch. Further, the tap with the smallest delay amount is connected to 802 -1 and the tap with the largest delay amount is connected to 802 -d. Even if the probe frequency changes, the number d of taps in the delay line circuit 7 is kept unchanged. Note that as the probe frequency increases, the partial delay line circuit DL with the larger amount of delay
is gradually becoming less and less used. The partial delay line circuit DL is D
The output terminal 804 is connected in series by the A and B terminals of L.
is output to.

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 amount of delay is required and the price of the device increases. So, for example, 3.5M
Hz so that the delay line circuit 7 has the maximum delay amount, and
．． At 5MHz, the maximum delay amount is the same as at 3.5MHz. In other words, at 2.5MHz, the number of taps is d.
become smaller. Such usage is also possible with this method.

FIG. 15 shows 803-1 to 803 in FIG.
-k is the partial delay line circuit DL used. 901
is probe frequency 2.5MHz, 3.5MHz, 5
．． This is an input section for each tap for 0 MHz and 7.5 MHz, and 902 is a constant current amplifier, which serves as an input section for connecting the partial delay line circuits DL. 9
03 is also a constant current amplifier, with F1, F2, F on the input side.
A resistor is provided for adding currents to signals from either F3 or F4.

Reference numeral 904 is a constant current amplifier, which serves as an output section for connecting the partial delay line circuits DL. Variable gain amplifiers 902 and 904 separate unused partial delay line circuits DL. Further, 904 has a resistor on the input side for terminating the delay line 906. Reference numeral 905 represents a terminal resistor on the input side, and reference numeral 906 represents a delay line, which is composed of, for example, 12 delay elements with tde = 18 nsec. For 7.5MHz, 2×tde (36nse
c) If you make a tap every time, you will get 6 taps. (F4) For 5.0MHz, 3×tde (54nse
c) If you make a tap every time, you will get 4 taps. (F3) For 3.5MHz, 4×tde (72nse
c) If you make a tap every time, you will get 3 taps. (F2) For 2.5MHz, 6×tde (108ns
If you make a tap every time (ec), you will get 2 taps. (F1
) Furthermore, the delay line 906 may be further divided into two parts, for example, and a constant current amplifier may be connected between the parts. Dividing in this manner is advantageous for frequency characteristics and reflection within the partial delay line circuit DL.

[0063]

Effects of the Invention As is clear from the above description, the present invention reduces the influence of attenuation caused by living organisms by suppressing the amount of focus control by carrier wave phase control, and reduces the delay line circuit to a single point.
By using a system, a low-cost delay line can be realized.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram showing the principle of diagnosis using ultrasound.

FIG. 3 is an explanatory diagram of phase.

FIG. 4 is a diagram illustrating the 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 example in which there are two systems from the multiplication circuit group.

FIG. 7 is a diagram showing an example in which there is one multiplication circuit group.

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

[Figure 9] Using a matrix switch in Figure 8
FIG. 4 is a diagram showing a case where four inputs are used.

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

FIG. 11 is a timing chart of FIG. 10;

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

FIG. 13 is a timing chart of FIG. 12;

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 Transmission circuit (control circuit of transmission driver circuit) 2
2-1, 2-2, ..., 2-n ultrasonic vibration element 3
3-1, 3-2, ..., 3-n Transmitting/receiving circuit group 4
Multiplication circuit group 5 5-1, 5-2 SW circuit group 6 Switching circuit group 7 Delay line circuit 8 Log amplifier 9 Display

Claims (5)

[Claims] 1. An ultrasonic probe composed of ultrasonic transducer elements (2) arranged in a predetermined shape, and a desired transmission driver of a transmitting/receiving circuit (3) are selected and the corresponding ultrasonic transducer elements ( 2) a transmitting circuit (1) that outputs a control signal for transmitting an ultrasonic pulse to a subject and emitting a focused ultrasonic pulse at a desired depth position of the subject; The reflected waves from the object are received from each of the ultrasonic transducer elements (2), and the received signals are subjected to delay time control and phase control corresponding to each signal and then added, thereby focusing on a desired depth position. In an ultrasonic diagnostic apparatus comprising a receiving circuit system (3, 4, 5, 6, 7) capable of performing Circuit system (3, 4, 5
, 6, 7) have at least two gain-variable amplifiers per element of the ultrasonic vibration element (2),
A multiplication circuit (4) whose components include a circuit that can control the gain allocation of these two amplifiers, and an output corresponding to the output of each of the ultrasonic transducer elements (2) of this multiplication circuit (4). A first switch circuit (5-1) and a second switch circuit (
5-2), and has taps corresponding to the output terminals of the first switch circuit (5-1) and the second switch circuit (5-2), and changes the amount of delay of the input signal depending on the position of this tap. Delay line circuit (7) and this delay line circuit (7)
and a switching circuit (6) that generates less noise during switching, which switches and connects the tap and the corresponding output terminal of the first switch circuit (5-1) or the second switch circuit (5-2), When the first switch circuit (5-1) or the second switch circuit (5-2) is connected to the delay line circuit (7), each of the ultrasonic transducer elements ( 2) to the desired output terminal, and connect the two output terminals of the two variable gain amplifiers, which are the components of the multiplication circuit (4), to the delay line circuit (4). 7) An ultrasonic diagnostic apparatus characterized in that the appropriate two taps are formed into a pair, and the pair can be switched and connected to any pair of the configured pairs by selecting an appropriate interval. 2. The multiplication circuit (4) has two variable gain circuits per element of the ultrasonic vibration element (2).
The first set consists of a first circuit and a second circuit having an amplifier, and is constructed by selecting appropriate two taps of the delay line circuit (7) as a pair, and selecting the pairs at appropriate intervals, and a first set configured by selecting the pairs at appropriate intervals; 2 output terminals of the two variable gain amplifiers of the first circuit can be switched and connected to any pair of the first set, and the second circuit 2
2. The ultrasonic diagnostic apparatus according to claim 1, wherein the two output terminals of the variable gain amplifiers can be switched and connected to any pair of the second set. 3. The multiplication circuit (4) has two variable gain amplifiers per element of the ultrasonic transducer (2), and one of the two variable gain amplifiers is a first variable gain amplifier. A signal is supplied to the first switch circuit (5-1) and the second switch circuit (5-2) from the first switch circuit (5-1), and the other second variable gain amplifier is supplied independently from the signal line from the first variable gain amplifier. The first switch circuit (5-1) is also connected to the amplifier.
The ultrasonic diagnostic apparatus according to claim 1, wherein the signal is supplied to the second switch circuit (5-2). [Claim 4] From the first variable gain amplifier, +
A first output with polarity and a second output with negative polarity are output, a third output with positive polarity and a fourth output with negative polarity are output from the second variable gain amplifier, and a tap of the delay line circuit (7) is output. The interval is 1/4 period of a specific frequency period within the change range of the carrier frequency of the ultrasonic signal due to attenuation in the living body, and the delay amount is calculated by pairing two adjacent taps of the delay line circuit (7). When the delay amount tap pairs are numbered in order, the first switch circuit (5-1) or the second switch circuit (5-2)
In either switch system, two outputs of one polarity of two differential outputs are connected to two taps of an odd-numbered pair of the delay line circuit (7), and two outputs of one polarity of the two differential outputs are connected to two taps of an even-numbered pair. The two outputs of the side polarity are connected, and when the odd numbered output is connected, the gain control of the two variable gain amplifiers is cos
(p), sin (p), the gain control of two variable gain amplifiers is cos when connected evenly.
(-π+p) and sin(-π+p), the ultrasonic diagnostic apparatus according to claim 3. 5. The delay time between the taps of the delay line constituting the delay line circuit (7) is set to a probe frequency of 2.5 MH.
z, 3.5MHz, 5.0MHz, 7.5MHz
The ratio is 6:4:3:2, and the frequency is 7.5MHz.
5. The ultrasonic diagnostic apparatus according to claim 1, wherein an integer number of taps for all probe frequencies are arranged between 12 tap intervals of probe delay taps.