JPH01198536A - Phasing circuit for ultrasonic apparatus and ultrasonic diagnostic apparatus using the same - Google Patents

Abstract

PURPOSE:To achieve the miniaturization, cost reduction and enhancement of capacity of an apparatus by reducing the number of analogue switches, by a method wherein the signal lines connected to arranged vibrators receiving an ultrasonic wave are divided into a large number of sets and the output terminals of respective delay lines are alternately connected to the signal lines having no vibrators of cross point switches opposed to each other so as to be changed over. CONSTITUTION:Delay lines 101 each having a delay time equal to that between the taps of delay lines 31, 32 and having a large number of taps are provided at every signal lines from the vibrator elements of a probe. By selecting the signals from said delay lines by an analogue multiplexer 102, a delay time can be set with resolving power further smaller than the delay time. In order to convert the angle theta of deflection of ultrasonic beam in electron sector scanning from theta in the positive direction to -theta in a negative direction, analogue switches 91, 92 control which of terminals 1, M max. delay is given. A series of the opening and closing operations of an analogue multiplexer, cross point switches 41, 42 and the analogue switches 91, 92 are performed by a controller 105 and the angle of deflection of ultrasonic beam at the time of electron sector scanning and the delay time corresponding to a converging point are set at every channel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic sensor scanning ultrasonic diagnostic device,
In particular, the present invention relates to improvements in a receiving system that receives echo signals from ultrasound emitted from a probe into a living body.

(Prior art) Electronic scanning ultrasound technology that diagnoses living organisms based on the reflected echoes of ultrasound beams emitted into a subject.
Wave diagnosis and equipment have been put into practical use. In such devices, a probe in which a large number of transducer elements are arranged is used as a probe that is involved in transmitting ultrasonic waves into the living body and receiving reflected echoes. The convergence is
It is given by delaying the electrical signals from the above-mentioned transducer element group by an appropriate amount and adding them. Such a circuit is called a phasing circuit.

A specific example conventionally used as the above-mentioned phasing circuit is shown in FIG.

The echo signal received by the transducer element group of the probe is a low-level analog signal, and in order to handle it, a phasing circuit consisting of a lumped electromagnetic delay line consisting of an inductor and a capacitor and an analog switch is used. The circuit has been put into practical use. The phasing circuit of FIG. 4(a) is provided with variable delay lines 10A to IOM that provide the required variable delay time to the received signals (1 to M) from each transducer element, and The delayed signals are added by an adder 20. The circuit shown in FIG. 4(b) is a circuit that sequentially adds signals from each transducer element by adders 20a to 20(m-1) via small variable delay lines 10a to 10(m-1). It is structured. In any of the above, the variable delay line is a delay line provided with taps, and the directivity and focusing are achieved by selectively switching the taps with an analog switch. The method shown in FIG. 4(a) requires a long delay time in the variable delay line when performing sector scanning in which the ultrasound beam is deflected and scanned.
To provide a delay line for each transducer element.

The size of the device becomes large and expensive.

Furthermore, in the method of FIG. 4(b), the delay time required for each variable delay line is shorter than in the method of (a), but the signal passes through the adder more times, and the S/ This tends to cause a decrease in N. In addition, since the delay time offset in the adder is accumulated, a delay time setting error is likely to occur. Fig. 4 (Q) shows that a constant current signal is injected into the tapped delay line 30 (hereinafter simply referred to as a delay line). In addition to giving the echo signal a delay time determined by the tap position, it also has the function of adding up the signals applied to each tap. Here, the signal from each transducer element is guided to a plurality of corresponding signal lines 1 to M, and these signal lines and a plurality of signal lines connected to each tap of the delay line are orthogonal to each other. A crosspoint switch 40 consisting of an analog switch 50 provided at the intersection of the signal lines allows connection to any tap of the delay line. This method has recently attracted attention because it can eliminate the drawbacks of the methods shown in FIGS. 4(a) and 4(b) (Ultrasonic Equipment Handbook, published April 20, 1985).

Since this method requires a cross-point switch, the required number of analog switches 50 increases rapidly as the number of transducer elements and the number of delay line taps increase. Recently, cross-point switches have been developed as LSIs for use in space division switches for telephone lines, and their prices have declined. This unavoidable ground capacitance of the switch increases as the number of switches increases, and this causes deterioration of the frequency characteristics of the signal. This will be explained in more detail with reference to FIG.

The configuration of the phasing circuit according to the conventional method shown in FIG. 4(c) is shown in FIG. 5, where the transducer element number of the probe is M.
Then, M channel signals are input to the phasing circuit. Now, the number of taps of the delay line 30 is set from 0 to N (N
+1), the cross point switch 40 is (M
It is composed of X (N+1)) analog switches 50. A signal is input to this cross-point switch 40 from each vibrator element via a voltage-current converter 60 that converts an input signal voltage into a constant current signal. The output terminal of the cross point switch 40 is a constant current signal buffer 70 with low input impedance and high output impedance.
through the tapped delay line 3- with the tap gap delay time T.
0 taps 0 to N. 0MO8 elements are used as analog switches in the crosspoint switch. A common-base transistor circuit is used as a constant current signal source, and a circuit with an impedance sufficiently larger than the characteristic impedance of the delay line is connected to the tap to prevent deterioration of the performance of the delay line. There is.

A signal voltage from the vibrator element is applied as a constant current signal to the input terminal of the cross-point switch 40 by the voltage-current converter 60. The signals applied to the input terminals 1゜2, . . . 9M are changed by opening and closing the analog switch 50.
It can be connected to a constant current signal source buffer 70 connected to any tap of the delay line 30. Since the signal passing through the cross point switch 40 is a constant current signal,
From multiple inputs of the crosspoint switch 40 to taps of the same delay line 30, i.e., the crosspoint switch 40
When connected to the output terminal of the delay line 30, these signals are connected to the output terminal of the delay line 30
, and the signal is transmitted to the output tap of the delay line 30. Note that, due to the operating principle of the phasing circuit, a switching operation is not performed in which signals from the same transducer element are simultaneously distributed to taps of different delay lines.

By the above operation, input terminals 1, 2, 3. ...Every signal applied to M is connected to one of the taps of the delay line, and after giving a maximum delay of nXT, n,IO,1
,2,−,any integer up to N.

It is clear that all these signals are summed at delay line 30.

In an analog switch made up of eight CMO elements constituting a cross-point switch, the source and drain of the MDS transistor correspond to the input/output terminals of the switch, and a capacitance exists between the source and drain and the ground. This capacitance accumulates in proportion to the number of switches, so this capacitance becomes the capacitance that enters in parallel with the load of the voltage/current exchanger 60 or the input impedance of the constant current signal buffer 70, and the signal passing through the switch To avoid this, it is desirable to reduce the number of analog switches as much as possible while keeping the same number of transducer elements and taps.

[Problem to be solved by the invention]

In order to improve the performance of an electronic sector scanning ultrasonic diagnostic device, the above conventional technology increases the number of transducer elements of the probe, increases the aperture of the probe, and increases the deflection angle of sector scanning. No consideration was given to the increase in the number of analog switches required for the phasing circuit, resulting in an increase in size and price, and deterioration of frequency characteristics.

The first object of the present invention is to reduce the number of analog switches required in the phasing circuit of an electronic sector scanning ultrasonic diagnostic device, thereby making the device smaller and cheaper.

The purpose is to measure performance improvement.

The second problem of the present invention is to apply the above-mentioned phasing circuit configuration technology to a phasing circuit configuration technology that can be easily applied to devices with an increased number of oscillators and inexpensive devices that do not. Our goal is to provide the following.

[Means to solve the problem]

The above-mentioned first problem is solved by a first invention in which a phasing circuit of an electronic sector scanning ultrasonic diagnostic apparatus is configured as follows.

That is, the phasing circuit of the present invention divides the signal lines connected to the array transducer that receives ultrasonic waves into a plurality of sets, and divides each set of signal lines into at least one set for each set of signal lines. One more signal line is used as a first signal line, and a plurality of second signal lines are provided that intersect with this first signal line, and the intersection of the first signal line and the second signal line is A combinational circuit constituted by a cross-point switch provided with a switch and a delay line having a plurality of taps connected to the second signal line is provided for the number of divisions of the signal line connected to the vibrator, The present invention is characterized in that a delay time adding means is provided for selectively connecting the output end of each delay line to the input terminal of the signal line without a vibrator of the opposing cross-point switch.

The second challenge was to configure a board with a combination circuit of the cross-point switch of the phasing circuit and the delay line connected to the cross-point switch as a block, and to create a board that corresponds to the number of transducer elements of the device's probe. This is achieved by configuring a phasing circuit with several blocks.

[Effect]

In the first invention for solving the first problem, the received signal is transmitted by switching the crosspoint switch.
The received signal is inputted to any one of the plurality of signal lines connected to the delay line, that is, the second signal line, from the input signal line. Therefore, since the received signal can be input to any tap of the delay line connected to the crosspoint switch, any delay time can be given to the received signal. However, for signals whose maximum delay time of this delay line is not enough for a predetermined delay time, the received signal is added from the output terminal of the delay line via delay time addition means to the oscillator of the opposing crosspoint switch. Input from the signal line via the switch to the designated tap of the delay line connected to the opposing crosspoint switch. This compensates for the insufficient delay time, and by switching the delay time adding means, the deflection angle of the ultrasonic beam for sector scanning can be made positive or negative.

As a result, the number of switches in the crosspoint switch can be significantly reduced, and deterioration of high frequencies can be prevented.

In the second invention for solving the second problem, the number of transducer elements of the probe connected to the ultrasonic diagnostic apparatus is 32.
64 elements, etc., and if a 32-element probe is connected to one device and a 64-element probe is connected to another device, one block is connected to a crosspoint switch corresponding to 32 elements and a delay. A phasing circuit block is constructed with the 64
The element device is handled by using two phasing circuit blocks, that is, two substrates.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

First, the principle of the present invention will be explained with reference to FIG.

The phasing circuit shown in FIG. 1 can perform the same operation as the phasing circuit having the configuration shown in FIG. 4(c), but has a reduced number of analog switches. Its configuration is to divide the delay line 30 in FIG. 4(c) into two, and to arrange crosspoint switches 40A and 40B (these correspond to approximately 1/4 of the crosspoint switch 40) in parallel to the delay line. However, the outputs of the delay lines can be input to mutually opposing crosspoint switches.

Here, in the delay lines 31 and 32, the delay time between each tap is T, and the number of taps is 0 to N/2 and (N/2)+O to N.
There are (N/2)+1 delay lines consisting of (N/2)+1 delay lines. Here, the delay amount for tap numbers 0 and (N/2)+O is zero, and N is an even number. Therefore, the total delay time of each of delay lines 31 and 32 is (TXN/2), which is 172 of the total delay time (TXN) of delay line 30 in the configuration of FIG.

A crosspoint switch 41 is connected to each tap of the delay line 31 via a constant current signal buffer 70. This cross point switch 41 has input terminals 1, 2, 3, . . . , CN/2).

A signal line with SL and each also has an output terminal 0°1.
2,3. ..., (N/2) and the intersection of each of the signal lines, that is, ((N/2)+1)x((N/2
)+1) Analog switch 50 on the matrix
is arranged. Each signal voltage from the transducer element of the probe is input to the crosspoint switch 41 via the voltage-current converter 60.

On the other hand, the tap of the delay line 32 is connected to the crosspoint switch 42 via a constant current signal buffer 70, similarly to the delay line 31 described above. Similar to the cross-point switch 41, this cross-point switch 42 has analog switches 50 arranged as shown on a matrix of ((N/2)+1)X((N/2)+1), and the delay line The circuit configuration related to the crosspoint switch connected to tap No. 31 is the same.

A resistor having a resistance equal to the characteristic impedance of the delay line 31 and a value Ro is provided at the end of the delay line 31, and the other end is grounded. This resistance is 11R.

The terminals on the delay line 31 side include terminals 1, 2, 3 . ....

The signals from the transducer elements applied to N/2 are delayed by an arbitrary value from O to TX'n (where n is any integer from O to (N/2)). A signal voltage obtained by adding and combining the respective signals appears.

At the end of the delay line 32, that is, at one end of the terminating resistor RO of the delay line 32, there is a terminal (N/2)+1°(N/2)+
2. ...The signal voltage applied to 9M is a signal voltage that is delayed by an arbitrary value from O to TXn (where n is an arbitrary integer from 0 to (N/2)) to the signal from between the transducer elements. appear.

On the other hand, the terminal end of the delay line 31 is connected to the terminal Sz of the crosspoint switch 32 via an analog switch 82. Further, the terminal end of the delay line 32 is connected to the terminal S1 of the crosspoint switch 41 via an analog switch 81. Now close the analog switch 82,
When the analog switch 81 is opened, the cross point switch 41 is connected to the terminal S2 of the cross point switch 42.
The signal that has passed through the delay line 31 is sent to the analog switch 5.
The delay line 32 tap (N/2
)+O, (N/2)+1. . . , is applied to either terminal (N/2)+1. (N/2)+2. . . . is added together with the signal applied to 1M and appears at the end of the delay line 32. At this time, n is an integer from 0 to N. In other words, terminal 1°2.3. ...The signals applied to each of 9N/2 are.

An arbitrary delay is given by the delay line 31 from 0 to (N/2)
t, and the crosspoint switch 32 causes the delay line 32 to have taps (N/2)+O, (N/2)+1 . −
, N, and further from 0 to (N/2)X
After giving an arbitrary delay at the time interval up to T, the terminal (N/
2)+1. (N/2)+2. . . . The output signal can be taken out by the analog switch 90 after being outputted to the terminal end of the delay line 32 which is added together with the signal applied to 9M. Here are terminals 1, 2, 3. ....

The delay given to the signal applied to N/2 is from 0 to NT
, and terminal (N/2)+1. (N/2)+2. ...
The delay imparted to the signal applied to 2M is from O to (N
/2) Becomes XT.

To perform electronic sector scanning, the signal from the transducer element,
Here, terminals 1, 2, 3. . . 9M is the delay time to be given to the signal applied to the signal. When i does not take convergence into consideration, it is as shown in the following equation.

(1: (i 1)d/cXsinθHere, i is 1
, 2, 3. . . . M is the terminal number, d is the pitch between the transducer elements, θ is the deflection angle of the ultrasonic beam, and C is the sound speed in the living body.

When performing electronic sector scanning, it is sufficient that the transducer element has a larger delay time as it approaches the edge, and it is not necessary to give the same maximum delay time NT to the signals from all transducer elements. It is sufficient to give the maximum delay time to the transducer element M and the minimum delay time to the transducer element 1 at the other end.In this case, open the analog switch 82, close the analog switch 81, and connect the signal of the element M to the terminal. to N, and element 1
It is only necessary to control the signal so that it is input to the terminal O.

In addition, when deflecting the ultrasonic beam to 10 in the opposite direction to the above, the maximum delay time is given to terminal 1, and the delay time is increased as the number of terminal numbers decreases.
The control should be reversed to the above to give the maximum delay time. To do this, open the analog switch 81 and
By closing analog switch 82 and taking the signals from the end of delay line 32 via analog switch 90, each signal is given an appropriate delay and then summed.

From the above explanation, the phasing circuit shown in Fig. 1 is as shown in Fig. 4 (Q).
It has become clear that this phasing circuit can be used in a phasing circuit for electronic sector scanning, similar to the phasing circuit shown in . Figures 1 and 4 (
Q), the number of analog switches in the crosspoint switch increases from MX (1+N) to (2+
M)

The principle and operation of the present invention have been explained above using an example in which the circuit consisting of a cross-point switch and an extension line is divided into two parts, but a configuration in which the circuit is divided into three or more parts is also possible.

An example of the configuration of a phasing circuit to which the above principle is applied will be described below with reference to FIG. In a practical phasing circuit, a plurality of delay lines with a short delay time and delay lines with a long delay time are usually combined in order to increase the setting resolution of the delay time. In FIG. 2, in order to increase the setting resolution of the delay time, the delay line 101 has a delay time equal to the delay time T between the taps of the delay lines 31 and 32 and has a large number of taps.
is provided for each signal line from the transducer element of the probe.

The signals from the taps of the delay line 101 are selected by the analog multiplexer 102 so that the delay time can be set with a resolution even smaller than the delay time T described above.

voltage-current converter 60, cross point switch 41,
42. Analog switch 50. Constant current buffer 70. The delay lines 31 and 32 have the same structure and operation as in FIG. Here, analog switches 91 and 92 are analog switches 81 and 90 . It combines the functions of 82 and 90, and gives the maximum delay to either terminal 1 or M in order to change the deflection angle θ of the ultrasonic beam in electronic sector scanning from 0 in the positive direction to (-0) in the negative direction. It also plays the role of guiding the added signal through the delay lines 31 and 32 to the output terminal.

- Analog multiplexer 102. Cross point switches 31, 32. A series of opening and closing operations of the analog switches 91 and 92 are performed by the controller 105 so as to set a delay time for each channel according to the deflection angle and focal point of the ultrasonic beam during electronic sector scanning.

Next, a description will be given of how the apparatus shown in FIG. 2 is operated with convergence as shown in FIG. The ultrasonic beam is scanned between 10 and 0 to -0 by a probe in which groups of transducer elements corresponding to terminals 1 to M shown in FIG. 2 are arranged.

At the start of scanning.

The controller 105 closes the B contact of the analog switch 91 and closes the A contact of the analog switch 92 to indicate that the deflection angle θ of the ultrasonic beam is scanned from the positive direction, and then starts scanning. The ultrasonic beam is transmitted to the transducer element groups 1 through 1 through a transmitting circuit and a delay circuit (not shown).
It is radiated from M in 10 directions. Then, the reception of the ultrasonic waves reflected within the subject is amplified by the same transducer element group 1-M, and the received signals are sent to the terminals 1-M shown in FIG. This received signal is delayed by a phasing circuit controlled by the controller 105 so as to focus on point P within the subject.

This delay control is performed based on the geometric relationship shown in FIG. That is, draw a straight line passing through the center of each vibrator and point P, draw an arc whose radius is the distance between point P and the center of the vibrator furthest from point P, and connect this arc to the center of each vibrator above. Find the point of intersection with the straight line passing through point P, and find the distance Lor between this point of intersection and the center of each vibrator. The delay time τ' is obtained by dividing @Lot by the speed of sound in the living body. This delay time τ amount' is set by the delay line 11 and delay lines 31 and 32.

Therefore, the controller 105 controls the analog multiplexer 10
2. The cross point switches 41 and 42 are controlled to connect each terminal 1 to M to a predetermined terminal of the delay lines 101, 31 and 32. As a result, the above-mentioned delay time τi' is given to the received signals inputted to each terminal 1 to M, and these signals are added within the delay lines 31 and 32, and the analog switch 9
The signal is outputted through the a contact point No. 2 and sent to an amplification/detection circuit and a digital scanner converter (not shown).

This operation is repeated by successively changing the delay time in small increments in the direction of decreasing θ, and when 0=0, the analog switch 91 is switched to the a contact, and then 0
When is in the negative direction.

The controller 105 issues a control command to switch the analog switch 92 to the b contact. Then, the above operation is performed until θ reaches -0 as shown in the figure, and one scan of the fan-shaped area shown in the figure is completed.

The received signal for each operation is amplified and detected in the same way as described above.
It is sent to a digital scan converter and converted into an image for CR.
Displayed at T.

Next, a second embodiment of the present invention will be described using FIG. 6. FIG. 6 shows a configuration in which the part indicated by the broken line in FIG. /
2, a second signal line.

A cross-point switch 41 with a switch 50 provided at each intersection of the first signal line and the second signal line, and a tapped delay line 3 connected to the second signal line of the cross-point switch 41
1 and an analog switch 91 connected to the output line of the delay line 31 are arranged on one substrate 200. If an ultrasonic diagnostic apparatus is constructed in which a probe with a transducer element of M/2 is connected, the phasing circuit will only need to incorporate one board 200 into the apparatus. When configuring an M ultrasonic diagnostic apparatus with twice the number of transducer elements, one more board 200 is added as shown by the broken line in FIG. By controlling this with a controller as shown in FIG. 2, a phasing circuit can be easily constructed.

Therefore, according to this embodiment, it is possible to set up both a device with a large number of transducer elements to achieve high image quality and a device with a small number of transducer elements aimed at low cost. Phase circuits are easy to construct. Further, since the block phasing circuit is made into a substrate and shared, mass production is possible, and the cost can be reduced more than simply by reducing the number of analog switches 50.

In the second embodiment, the analog switch 91 is provided on the board, but it may also be provided outside the board. By doing so, only one phasing circuit block is used. This is effective in reducing equipment costs.

〔Effect of the invention〕

According to the phasing circuit of the present invention, by dividing the delay line into a plurality of parts, the number of analog switches required can be reduced by approximately 1/2 to 1/3, depending on the number of divisions, compared to conventional methods. Because the number of parts can be reduced, the device can be made smaller and lower in price.

Also, by reducing the number of analog switches mentioned above,
Since the capacitance added to related circuits is reduced, the pass frequency limit is improved, and performance can be easily improved. By using it in an ultrasonic diagnostic device, it is possible to improve image quality and reduce costs.

Furthermore, the fact that the delay lines 31 and 32 are constructed from a plurality of similar delay circuits as shown in the embodiment of FIG. Although it is not very expensive, it is possible to construct a phasing circuit using only a part of the delay circuit of the configuration shown in FIG. 2 for a low-cost device. That is, a phasing circuit for an M/2 channel probe can be realized with a delay circuit consisting only of the delay line 31.

As described above, the method of the present invention has the feature that it can be used for devices with a large number of channels by combining a plurality of circuits of one type, and that circuits can be easily standardized for devices with different performances.

This divided circuit A is also used for electronic linear and phasing circuits of ultrasonic diagnostic equipment.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram illustrating the principle of a phasing circuit for an ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is a circuit diagram illustrating an example of the configuration of a phasing circuit constructed using the principle shown in FIG. 1. FIG. 3 is a schematic diagram illustrating the relationship between the delay time and the deflection angle and focusing of the ultrasonic beam in electronic sector scanning, FIG. 4 is a diagram illustrating a typical example of a conventional phasing circuit, and FIG. 5 is shown in Figure 4 (c
), and FIG. 6 is a diagram illustrating a combination of phasing circuits formed into a substrate. 1-M... Reception signal terminal, 30-32... Delay line with tap, 40-42... Cross point switch, 0
~N/2~N... Delay line tap, 50... Analog switch, 60... Voltage-current converter, 7o... Constant current buffer, 81.82... Analog switch, 9
0 to 92... Analog switch, 101... Delay line with tap, 102... Analog multiplexer, No.
Figure 1 3rd 40th 5th

Claims (1)

[Claims] 1. A phasing circuit for an ultrasonic diagnostic device that transmits and receives ultrasound beams using a plurality of arrayed transducers to scan a cross section of a subject in a fan-shaped manner and visualize the image, which A cross-point switch in which a switch is provided at the intersection of a plurality of first signal lines into which at least one more signal is input and a plurality of second signal lines that intersect the signal lines; A plurality of sets of combinational circuits each consisting of a tapped delay line using the second signal line group as an input line are provided, and an input terminal of a signal line without an oscillator of a cross-point switch that faces the output of each tapped delay line. What is claimed is: 1. A phasing circuit for an ultrasonic diagnostic apparatus, characterized in that the phasing circuit is configured to include delay time adding means selectively connected to the phasing circuit. 2. An electronic sector scanning ultrasonic diagnostic apparatus comprising the phasing circuit according to claim 1. 3. A first signal line, each of which has at least one more signal line than the plurality of signal lines into which signals are input from the vibrator, and a plurality of second signal lines that intersect with the first signal line; , a crosspoint switch consisting of a plurality of switches provided at the intersection of the first signal line and the second signal line, and a tapped delay using the second signal line group of the crosspoint switch as an input line. A phasing circuit in which a circuit is arranged on a single substrate on a single substrate, and a switch for switching the output in two directions is connected to the output terminal of the tapped delay line.