JPS6284748A - Ultrasonic receiving phaser - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a receiving phaser for an electronic scanning ultrasonic tomography apparatus.

[Background of the invention]

Japanese Patent Publication No. 57-52057 discloses a receiving phaser using pre-delay means for phasing a received signal with a relatively short delay time and main delay means for phasing a received signal with a relatively long delay time. ing. Here, as a delay means, the analog L
-C bullet wire, charge phase shift elements, digital memory, etc. were used.

Furthermore, it has not been possible to switch the delay means during the reception period because switching noise occurs.

[Purpose of the invention]

The present invention uses a method that determines whether the ultrasonic beam is convergent during the reception period or not. It is an object of the present invention to provide a receiving phaser that enables sidynamic focusing by switching a plurality of adding means that combine and add the outputs of pre-delay means at the same time as switching the delay means.

[Summary of the invention]

In order to achieve such an object, the present invention is provided with a main four-grinding means having a holding means and a storage means, and a switching time of the pre-delay means, a switching time of the adding means, and a holding time of the holding means. By synchronizing the signals and holding them in the holding means at the time when the switching noise that occurred at each switching time disappears, the influence of the switching noise is removed, the signal is stored in the storage means, and the received signal is phased. It is something.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure 1 is an explanatory diagram of dynamic focus of received waves.
Tl * Tt I... T is each element of the array transducer, R1 and Rz are the depths, At, Bs (!=1°2,
..., n) is γ) connecting each element and depth Rs * Rz
(), the centers of arcs OA+ and OB+ are R1°R12, respectively.
, Ikugo OR+, and ORz are circular arcs.

In order to perform reception dynamic focusing, in order to phase the reception signal from the depth R1, the array element T+ is TlA.
In order to compensate for the delay time corresponding to the distance l and to phase the received signal from the deep hole 2, it is necessary to compensate the delay time corresponding to the distance TIB+.

A receiver phaser can be realized by having a pre-delay means for compensating a minute delay time corresponding to the minute distance of T3A3 and a main delay means corresponding to T3A3.

In order to perform reception dynamic focusing, the pre-delay means and the main delay means may be controlled so that the reception beam is converged at each depth.

FIG. 2 shows a conventional example, 1, 2. ..., n is an array element, 10-2...1O-(n-1) is a pre-delay element, 11-1...11-m is a holding circuit, 12-
1...12-m is the main delay element, 13-1, old,
・13-m is a pre-delay adder, 19-1...
19-m is the output of the main delay, 20 is the adder, and 3o is the receiving phaser output terminal. However, m=n/3 (m: positive integer). Here, the circuit up to the adder 13 will be referred to as pre-delay means, and the circuit subsequent thereto will be referred to as main delay means. Here, the delay time τ between the previous IIt delay elements is the electron pitch d1, the deflection angle θ
, is known to be given by the speed of sound C. In the case of FIG. 2, the predelay elements 10-2, 10-5. ..., 1O-(n-1)
The delay time is τ! and predelay element 10-3.10
-6. =, 10-(n-2) has a delay time of 2TI. Also, the delay time T2 of the main delay element can be found from the drawing in Figure 1, but in reality, the received signal reaches the element at the center of the aperture first, so the received signal at the center of the aperture is replaced by the received signal at the outside of the aperture. need to be delayed.

Although the configuration shown in FIG. 2 allows wave reception, the timing of switching between front lf and delay during the wave reception period will be explained using FIG. 3(a) and FIG. 3Cb).

Reference numeral 10 in FIG. 3(a) indicates a pre-delay element, such as a tapped inductance (L) or capacitance (C) delay line. 14 is a multiplexer, α is a control signal for the holding circuit 11 and main delay element 12, β is multiplexer 1
4 control signal. As shown in FIG. 3(b), the control signal β is applied to the controller number α for a certain period of time! >O) in advance and synchronously. Here, it is assumed that the switching noise completely disappears after 7 hours. In this way, even if the predelay is switched by the multiplexer 14 during the reception period, the data held in the holding circuit 11 will not be affected by switching noise.

Next, the number of times the predelay is switched during the reception time will be explained.

It is sufficient to switch the pre-delay sequentially or read-wise depending on the convergence point of the receiving beam, but since the inter-channel directional characteristics of the main delay means are relatively wide, the number of switchings may be very small.

FIG. 4 shows an example of inter-channel directional characteristics of the main delay means.

Now, as shown in Fig. 2, the input of 3,
When the output is 1, the inter-channel directivity characteristic of the main delay corresponds to the case where the element pitch is 3d=1.92m in equation (2), and the first zero point θ0 is as follows. (Here d =
(0.64 degrees, λ = 0.43) As described above, since the inter-channel directivity characteristics of the main delay means are wide, it is only necessary to switch several points so that they overlap.

Therefore, as shown in FIGS. 1 and 4, for elements far from the center of the array element, the directivity characteristics of the predelay are IV, IIl.
, Il, and I need to be switched three times in this order.

On the other hand, the central array element does not need to be switched with the directional characteristic I unchanged.

As shown in Fig. 5, D+,
D wealth T Ds-+ ”, the outermost D
At a receiving aperture of 4, the pre-delay control signal β4 changes the directivity characteristic sequentially from 1 to 1. Partial diameter D3, D2
, Dt are changed sequentially as shown in the figure, but the switching points decrease.

In the above description, it is clear that the number of switching points varies depending on the configuration of receiving aperture, depth, and predelay.

Further, in the above description, a linear type sensor is assumed, but the same applies to a convex type vibrator as shown in FIG. Here, RO is the radius of curvature of the vibrator, and D is the total receiving aperture.

In FIG. 6, the transducer T outside the receiving aperture.

If the pre-delays of ~T3 are in phase, the inter-channel directivity characteristic of the main delay will be ■. Since the receiving beam needs to be formed at the convergence point hole, it is necessary to control the pre-delay so that the directivity characteristics of the outer transducers T1 to T3 are formed in the direction of {circle around (2)}.

7th. FIG. 8 shows an embodiment of the present invention, 1°2.3・
..., n is an array oscillator, 10 is a predelay element, 1
3 is an adder, 1, 2 .・・・・・・9m (or m'
) is the output of the adder 13. (a) When the array camera is equally divided in the array direction and combined into three pieces as shown in the figure, in order to match the phase of the wavefront of the received signal shown in Figure 1, it is necessary to do as shown in Figure 4. The pre-delay element is controlled so that the directivity characteristic with a pitch of 3d (d) - i array element pitch) becomes a pattern of ■ or H near the center of the aperture, and a pattern of ■ or ■ outside the aperture. Therefore, the maximum value of the pre-# delay time is determined by the outermost pre-delay element. On the other hand, since the predelay time may be small near the center of the aperture, the output of the predelay element is reduced to 3 as shown in FIG. 7(b).
It is possible to match the phase even if more than 1 is added.

This combination is optimally designed by the diameter of the array camera and the position of the convergence point.

FIG. 8 shows a specific example of the present invention, and 21 is a switch with n inputs and m outputs. 22 is a control circuit that generates a control signal for switching the switch 21; Although the numbers of outputs of the switching devices 21-1 and 21-2 are different as shown in FIG. 7, they are shown to be the same in FIG. 8 for the sake of simplification of explanation. 11 is a holding circuit similar to that shown in FIG. Similarly to FIG. 3(b), the switching timings β1' and β2' of the control circuit 22, which will be described later, are changed to the holding timing α of the holding circuit 11 in the same manner as the switching timing β of the pre-delay element shown in FIG. 3(b). Let it advance by a certain amount of time T. For the same reason as mentioned above, the switching noise of the switching device 21 is not mixed into the received signal, so dynamic focusing of the received wave becomes possible.

In FIG. 9, there is a switch 21, 23 is an operational amplifier, 24 is a control signal β' input terminal, and SW is ON when a control signal is present.
The switch R is a resistor that is turned off when there is no power. With such a configuration, it is clear that the addition operation shown in FIG. 7 is performed when a control signal is present.

FIG. 10 is an example of a time chart of the control signal β' of the control circuit 22, where t=0 is the transmission time, β1' is the control signal of the switch 21-1 in FIG. -2 control signal.

The present invention is effective not only for linear type probes but also for convex type probes as shown in FIG.

Further, in the above explanation, the aperture is not changed in the depth direction. However, as the distance becomes shorter, a so-called variable aperture is effective, as it is possible to obtain good resolution with a relatively short delay time by reducing the aperture. The present invention is also effective in combination with the variable aperture described above.

Furthermore, it is clear that the present invention is effective even when the delay time of the pre-delay element in the present invention is zero.

In this way, according to the present invention, the delay time of the predelay element,
It becomes possible to switch the combination of outputs in the depth direction, and fluorescent wave dynamic focusing becomes possible.

Therefore, the performance of the ultrasonic diagnostic apparatus can be improved, which greatly contributes to diagnosis.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the present invention, Fig. 2 is a diagram showing an embodiment of the present invention, Fig. 3 (a) is a diagram showing an embodiment of the present invention, and the figure Φ
) is a diagram showing the operation, FIGS. 4 and 5 are diagrams showing the operation of the present invention, FIG. 6 is a diagram showing the directivity characteristics of the predelay in a convex type vibrator, and FIGS. 7 to 10. FIG. 1 is a diagram showing an embodiment of the present invention. 10... Pre-delay element, 11... Holding circuit, 13...
...Adder, 21...Switching circuit. Agent Patent attorney Katsuo Ogawa-1, C゛fu 1 Figure ¥J Z Figure 13 (6shiji (b) ¥:J 4 Figure 5)

Claims (1)

[Claims] Pre-delay means for phasing minute delays in an ultrasonic tomography device that deflects and focuses an ultrasound beam to obtain a tomographic image by controlling the amplitude and phase of the transmitted or received signals of each element of an array transducer. , a main delay means for phasing a relatively large delay, a plurality of addition means for combining and adding the outputs of the pre-delay means, and a switching means for the plurality of addition means, the main delay means The reception means is composed of a holding means and a storage means, and the pre-delay means is switched depending on the convergence point of the ultrasonic beam, and at the same time, each time at which the adding means is switched is synchronized with the time held by the holding means. An ultrasonic receiver phasing device characterized by phasing wave signals.