JPS62299244A - Ultrasonic diagnostic apparatus - 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] 3. Detailed description of the invention [Field of application of the invention] The present invention relates to an ultrasonic diagnostic device, particularly a high-resolution ultrasonic diagnostic device.

The present invention relates to an ultrasonic diagnostic apparatus suitable for high-speed imaging.

[Background of the invention]

First, the conventional device shown in Japanese Unexamined Patent Publication No. 56-112234 is used as the first example. It is equipped with #2 set of phasers, which will be explained using Fig. 2, and the depth of focus is alternately switched for ultrasound beams in the same direction. The receiving focus is moved by changing the taps of the phaser. but.

Two sets of phasers are required to obtain a received signal corresponding to one scanning line. Therefore, when attempting to further increase the imaging speed by obtaining a plurality of scanning lines, there is a drawback that the scale of the apparatus increases.

[Purpose of the invention]

An object of the present invention is to provide an ultrasonic device that can obtain high-resolution images at high speed.

[Simultaneous summary of invention]

There is a so-called dynamic focus method in which the focal position is moved in the depth direction in order to obtain a high-resolution image. When moving the focal point, if a normal tapped delay line is used and the taps are selected by a switch, switching noise will occur and the signal-to-noise ratio of the displayed image will deteriorate.

In order to achieve the above object, the present invention is characterized in that switching noise is stored in advance and is removed from the received signal.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to Fig. 3.4.5. In FIG. 3, 1 is a transmission beam focusing delay circuit;
2 is a driver, 3 is a probe consisting of a plurality of piezoelectric elements, 4
5 is a preamplifier, and 5 is a phaser with a plurality of inputs (n: a positive integer) and a single output, which includes a first switch 20. 6 is an analog-to-digital converter (A/D converter), 7 is a storage means consisting of a line memory, 8 is a digital-to-analog converter (D/A converter), 9 is a subtraction circuit, and 10 is a signal processing circuit. It performs nonlinear processing such as waveform compression and detection. 11 is a display circuit. 12 is a second switch for selecting the input of the preamplifier 4; 13 is a third switch for selecting the destination of the output of the phaser 5; 14 is a control circuit; 2. In addition to controlling the third switch, it also controls writing (Vrite, abbreviated as W) and read (read, abbreviated as R) of the line memory 7.

Figure 4 is a time chart, showing the transmission signal launch period (a
), timing of memory 7 (b) and display section (c)
It is shown. Figure 5 shows the received signal waveform, and shows the launch period (a), switching noise (d), sum of the received signal and switching noise (θ), and received signal (e) - (d). There is.

The operation of an embodiment of the present invention will be described with reference to FIGS. 3 to 5.

The transmission trigger is input to the delay circuit 1 at every ejection cycle (for example, 300 μs), and a plurality of (n: positive integer) phase-controlled control signals are outputted so as to obtain a focused transmission beam, and input to the driver 2. do. The driver 2 generates high-voltage pulses to drive multiple piezoelectric elements of the probe 3 and transmit a focused ultrasound beam. The reflected ultrasound from the subject is received by the same probe 3, passes through the second switch 12 and the preamplifier 4, and is input to the phasing circuit 5. Here, the switch 12 is grounded when writing (W) to the memory 7, as shown in FIG.
It is assumed that the control is performed so that the contact 3 is connected at the time of reading (R). Further, the output of the phaser 5 is transferred to the third switch 13.
Therefore, when the second switch 12 is grounded, the phaser 5
When the second switch (12) is connected to the contactor 3, the output of the phaser 5 is sent to the subtracter 9.
This is one of the inputs.

In addition, the output of the line memory 7 passes through the D/A converter 8,
This becomes the other input of the subtractor 9.

The phaser 5 includes a first switch 20, an inductance-capacitance delay line 21, and a buffer amplifier 22. The received signals from the plurality of piezoelectric elements pass through the preamplifier 4 and are input to the switch 20.

The n outputs of the switch 20 select taps of the delay line 21 so that the received ultrasonic beam 11 is focused, and the summed output passes through the buffer amplifier 22 and becomes the output of the phaser 5.

When moving the focal point of the receiving beam 11 for one wave transmitting trigger, it is necessary to switch this switch 20.
Switching noise occurs, which adversely affects the displayed image on the display 11.

By controlling the first to third switching devices as described above,
The contents of line memory 7 are switching noise ((d) in Figure 5).
is written. The output of the phaser 5 is the received signal waveform conversion noise (Fig. 5(e)), but by subtracting it from the contents of the line memory 7 (switching noise) using the subtracter 9, the linearity of the system can be improved. Assuming that, the required received signal (e) −(
d) is obtained.

As shown in FIG. 4, writing to the memory 7 is performed every frame period. However, it is clear that there is no need to be limited to this. In principle, it is desirable to update the noise data every time the switching noise data changes.

For example, in the case of linear scanning, the switching noise pattern of focus movement is the same for each scanning line.

If the noise pattern did not change from frame to frame, the frequency of memory writes would be very low.

On the other hand, in the case of sector scanning, the noise pattern may be different for each scanning line, and it is necessary to prepare line memories equal to the number of scanning lines. However, it seems that memory capacity will not be such an issue in the future. Further, it is also possible to consider ways to reduce memory capacity (for example, a method of storing only switching noise).

It is also obvious that an analog memory such as a charge transfer memory (CCD) or a switched capacitor memory may be used as the storage means.

〔Effect of the invention〕

As described above, according to the present invention, by adding a simple circuit to the conventional device, it is possible to obtain a focused received signal without switching noise. Therefore, it greatly contributes to increasing the resolution of ultrasonic devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional device, FIG. 2 is a diagram showing a time chart of the operation of the conventional device, FIG. 3 is a diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing the device in FIG. 3. FIG. 5 is a diagram showing an explanation of the switching noise code. 3... Probe, 4... Amplifier, 5... Phaser, 6
...A/D converter, 7...line memory, 8...
D/A converter, 9... Subtractor, 11... Display, 1
2, 13, 2Q...Switcher. 5I! i+ Mouth 2nd figure h h Fs Ft Ft Ft#2
EnerX s hard((-no(dn)

Claims (1)

[Claims] 1. In an ultrasonic device that focuses an ultrasound beam and displays a tomographic image by controlling the phase of transmitted and received signals of a plurality of piezoelectric elements, a phasing means having a first switching means for switching the depth of focus and a storage means for storing the switching noise of the first switching means, a subtraction means, a second switching means for selecting the input of the storage means, and a third switching means for controlling the output of the phaser. . An ultrasonic diagnostic apparatus characterized in that when moving a focal point, a received signal without switching noise is obtained and displayed on a display means.