JPH0459896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is an ultra-high-performance ultrasonic technology that synthesizes echo signals so as to receive echoes while switching the focus in order to obtain echo images with good resolution over the entire area. The present invention relates to a signal editing circuit for a sonic diagnostic device.

(Conventional technology) Ultrasonic diagnostic equipment transmits ultrasonic waves into the subject,
Since the reflected waves differ depending on each tissue or lesion, this is converted into an image and displayed for diagnostic purposes. In this case, if you transmit and receive waves at a single focal point and display the reflected waves from a reflector at a long distance and the reflected waves from a reflector at a short distance on the same screen, it will not be possible to display the entire image in a good manner. It is difficult to display with resolution. To solve this problem, the reception dynamic focus method is used, in which the focal position is changed to follow the reflection source during reception, or the same area is scanned several times, and the transmission and reception focus is changed for each scan. A multi-stage focus method is used in which regions that provide the optimum resolution are edited via an image memory, and then connected and displayed on a display device. The receiving dynamic focus method is a method suitable for fast-moving organs because it receives waves at different focal points depending on the distance for each transmitted wave, so there is no need to reduce the image completion speed. Since the focus of the transmitted wave cannot be matched to all the focal points, the resolution is slightly inferior to the multi-stage focus method. However, in order to realize the receiving dynamic focus method using the focus switching method, it is necessary to have several types of electronic focus mechanisms and to assign each of them to each required focus position in advance. During wave reception, the signal path is switched so that the reflected wave in the corresponding section is connected to the output of the electronic focus means corresponding to the time period when the wave is being received.

(Problem to be Solved by the Invention) By the way, in such a switching type reception dynamic focus method, the optimal resolution is determined from the phased output signals of n sets of reception beamformers with different focuses. In order to obtain a single scanning line signal by connecting the obtained parts, the signals are switched in the high frequency section, intermediate frequency section, or video signal section to perform the connection. Noise entered the gap where the connections were made, appearing as white lines on the screen, and was especially noticeable in areas where the signal level was low. Although there is the problem that the image quality changes where the signal switches, the most problematic point is that white lines appear due to switching noise.

In order to avoid this, a post-demultiplexer consisting of a combination of delay lenses (focus determination means of the receiving beamformer) each having a different focal length is prepared in parallel for each focal point, and the received signal is detected and the frame is There is an idea to synthesize it at the point where it is written to the memory, at least to prevent the spike noise mixed in at high frequency from being detected and appearing as a white line, but the circuit size would be too large and it would be a problem in terms of cost. be.

The present invention has been made in view of the above-mentioned problems.The purpose of the present invention is to enable accurate data to be written to the frame memory even if the signal path is switched in the switching type reception dynamic focus method, and of course to enable the final To realize a signal editing circuit that does not include white lines on a display screen and has a simple configuration.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, and the present invention provides signal editing for an ultrasonic diagnostic apparatus that switches and combines signal paths in order to obtain images with good resolution over the entire region. In the circuit, a plurality of electronic focus control means for phasing and adding scanning line signals of different focuses, a plurality of delay means for respectively giving different delay times to output signals from the electronic focus control means, and an output to the delay means. a switching means for switching signals and combining them into one scanning line data; and a switching means for switching signals and combining them into one scanning line data; The present invention is characterized by comprising a write control means for performing write control.

(Operation) Scanning line signals in areas with different focal points are transmitted and received, and the received signals are phased and summed by the electronic focus means in each area, and then delayed by different delay times.
The switching means sequentially switches and synthesizes the delay-processed signals of each region at time intervals corresponding to the focal position, and after signal processing, removes the overlapped region signals together with the joints between the signals of adjacent regions with different delay times. and write it to frame memory.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, 1 is a transmitting trigger oscillator that emits a trigger signal for generating a transmitting pulse, and the output trigger signal is input to a transmitting beamformer to form a sound ray, so for example 64
Separated into line signals. 3 appropriately switches the 64 lines of input signals from the transmitting beamformer 2 to form and scan sound rays, and switches the reflected wave reception signal of each sound ray to generate 64 lines corresponding to the element position within the aperture plane. It is a scanner switch that recombines the signal into a signal, and is arranged in two stages in order to save on the number of switches, with a transmitter/receiver circuit 4 provided between the two stages. The transmitting/receiving circuit 4 includes a transmitting power amplifier, a transmitting/receiving changeover switch, a receiving amplifier, and the like. Reference numeral 5 denotes an ultrasonic probe array composed of a large number of transducer elements that receive a high-frequency signal for transmission, oscillate an ultrasonic wave, and receive a reflected wave and convert it into a high-frequency signal. 6A to 6D are four electronic focus circuits that classify the object into four zones according to distance, each of which is a receiving beam former.
The electronic focus circuit 6A is the closest zone 0,
The electronic focus circuit 6B receives the received signal based on the transmitted signal focused on the next closest zone 1, the electronic focus circuit 6C focuses on the next farthest zone 2, and the electronic focus circuit 6D focuses on the farthest zone 3. Perform phasing and addition. The scanner switch 3 distributes the received signals to the electronic focus circuits 6A to 6D. 7B is a delay circuit that delays the signal from the electronic focus circuit 6B by Δτ ₁ and outputs the F ₂ signal; 7C is a delay circuit that delays the signal from the electronic focus circuit 6C by Δτ ₂ and outputs the F ₃ signal; 7D is electronic focus circuit 6D
This is a delay circuit that delays the signal from F4 by _Δτ3 and outputs the _F4 signal. The electronic focus circuit 6A outputs an _F1 signal that is not subject to delay. The amount of delay has the following relationship.

Δτ ₃ >Δτ ₂ >Δτ ₁ >0 8 is the four scanning line signals F ₁ to F 1 with different focal positions
This is a focal zone switching switch that switches the _F4 signal at a timing corresponding to the distance of each focal position in zones 0 to 3, synthesizes it into one scanning line signal Fs, and outputs the signal. 9 is a bandpass filter (hereinafter referred to as BPF) that removes unnecessary high and low frequencies, and 10 is a level compressor that adapts the very wide dynamic range of the right signal to the characteristics of the photosensitive material and CRT. The output signal is detected by a detector 11 and converted into a digital signal by an AD converter 12. Reference numeral 13 denotes a write control logic circuit which includes a frame memory, a write address generator, a read address generator, a control circuit, etc., and removes a noise portion when writing the input scanning line signal to the frame memory. The noise-removed signal is displayed on the CRT, but the circuit below is the same as the normal circuit, so it will be omitted.

Next, the operation of the embodiment configured as described above will be explained. The trigger signal output from the transmit trigger oscillator 1 is converted into a 64-bit signal which is subjected to various delays in the transmit beam former 2. This output signal forms four identical sound rays with different focal positions. For example, in the first trigger signal, a phased _S1 signal focused on zone 0 is output. The second trigger signal outputs a phased S ₂ signal so that the same sound line focuses on zone 1,
Similarly, the _S3 signal of zone 2 and the _S4 signal of zone 3 are output. Each of the S ₁ to _{S 4} signals is sequentially distributed by a scanner switch 3 to form a sound ray, power amplified by a transmitter/receiver circuit 4, and then converted into an ultrasonic signal by an ultrasonic probe array 5 to be transmitted to the receiver. Waves are transmitted into the specimen. Ultrasonic signals reflected from a reflector within the subject are received by the ultrasound probe array 5 and converted into electrical signals. This received signal is amplified in the transmitter/receiver circuit 4, and the scanner switch 3
The signal is restored to the S ₁ to S ₄ signals by . The S ₁ signal is phased and added to the F ₁ signal having a focal position in zone 0 in an electronic focus circuit 6A. The S ₂ signal is phased and added to the signal having the focus position in zone 1 in the electronic focus circuit 6B, and is delayed by Δτ ₁ in the delay circuit 7B and output as the F ₂ signal. The _S3 signal is phased and summed by the electronic focus circuit 6C, and the _S4 signal is phased and summed by the electronic focus circuit 6D, and the delay circuit 7C
and F ₃ after receiving delays of Δτ ₂ and Δτ ₃ at 7D and 7D, respectively.
signal, output as F ₄ signal. F ₁ to _{F 4} above
The signals are switched and connected one after another by a focal zone changeover switch 8, and are combined into one scanning line signal F _S. Since the F ₂ to F ₄ signals have been delayed by different amounts of delay, the F _S signal combined with the undelayed F ₁ signal has a , the portion of the received signal corresponding to the difference in delay amount appears twice. In FIG. 2, A is the waveform of the F ₁ signal, and B is the waveform of the F ₂ signal. C is a diagram showing the switching timing of the focal zone changeover switch 8, and D is a waveform in which the F ₁ signal and the F ₂ signal are synthesized by the changeover of the focal zone changeover switch 8. As is clear from the figure, there are significant reflected waves a ₁ , b ₁ , c ₁ , d ₁ in the F ₁ signal of A.
If we pay attention to , the F ₂ signal in (b) becomes a ₂ , b ₂ , c ₂ , and d ₂ which have been delayed by Δτ ₁ . The F _S signal (2) is obtained by the switching control in (c), but in this F _S signal, the waveforms of the reflected waves b ₁ and b ₂ are sandwiched with the spike noise e generated by the switching of the focal zone changeover switch 8. They appear with a difference of Δτ ₁ . In other words, in the section b ₁ - b ₂ , the original signal is essentially 2
Appears multiple times in a row. Although not shown, signals with similar waveforms also appear at the joints between zone 1 and zone 2, and between zone 2 and zone 3.

This output F _S signal is like a normal device
The signal is processed by the BPF 9, the logarithmic amplifier 10, and the detector 11, and converted into a digital signal by the AD converter 12. Figure 2 D converted to digital signal
The F _S signal is written into the frame memory by the write address in the write control logic circuit 13, and the writing is performed as shown in FIG. That is, in the second F _S signal, the section D ₁ up to the reflected wave pulse b ₁ and the section D ₃ after the reflected wave pulse b ₂ are stored in the frame memory so as to restore the continuity in the original reflected wave signal. In the interval D ₂ between the reflected wave pulse b ₁ and the reflected wave pulse b ₂ , the writing is stopped by, for example, stopping the address progression of the frame memory, and the signal in that interval is not written. Therefore, the spike noise e existing in between is also substantially removed without being written. Spike noise is similarly removed between zones 1 and 2, and between zones 2 and 3. The waveform example shown in Figure 2 shows the case where the RF data of the reflected wave is written as is into the frame memory, but when writing the video data after detection, the same principle applies to writing while avoiding overlapping sections that include switching noise. The same objective can be achieved by doing so.

As explained above, the time width of the shift in the minute section corresponding to the difference in delay time depends on the width of the spike noise caused by switching, but since the spike noise is several hundred nanoseconds at most, the overlap section has no spikes. It is thought that a total of 1μS before and after the noise is sufficient, and this significantly changes the existing transmission and reception sequence in three locations: zone 0 and zone 1, zone 1 and zone 2, and zone 2 and zone 3. Nothing happens that you have to do.

In this way, according to this embodiment, by adding three delay circuits and slightly changing the write control of the conventional digital scan converter, white lines do not appear on the screen while maintaining the method of switching at the high frequency stage. A multi-stage focus method can be realized.

Note that the present invention is not limited to the above embodiments. For example, a circuit like that shown in FIG.
It may be used instead of B to 7D. In the figure, parts equivalent to those in FIG. 1 are given the same reference numerals.
In the figure, 15A is a BPF with a frequency bandwidth Δf ₁ with the center frequency f ₀ as the center frequency, and 15B is a BPF with the same center frequency f ₀
BPF with frequency bandwidth Δf ₂ , 15C is the center frequency
The BPF of f ₀ has a frequency bandwidth Δf ₃ , and 15D is the BPF of the frequency bandwidth Δf ₄ of the center frequency f ₀ . here,
The frequency bandwidth has the following relationship.

Δf ₁ >Δf ₂ >Δf ₃ >Δf ₄ The BPF is usually configured with an LC and causes a phase delay with respect to the input signal. Regarding the amount of delay, in the case of the same system, the narrower the frequency bandwidth, the longer the delay time, so the BPFs 15A to 15D can provide the same effect as the embodiment of FIG. 1.

Further, the BPF may be added instead of replacing the delay circuit. Furthermore, although four electronic focus circuits and four delay circuits have been described, the number can be freely selected.

(Effects of the Invention) As explained in detail above, according to the present invention,
Different amounts of delay are given to scanning line signals with different focuses, and these are switched and synthesized to create an overlapping part due to the difference in the delay amount in this composite signal, and to eliminate the spike noise caused by the switching. By removing this overlapping portion when writing the composite signal to the frame memory, the spike noise is also removed.
Even if the signal path is switched, only accurate data is written to the frame memory. As a result, of course, no white line appears on the final display screen. Furthermore, as mentioned above, by giving different amounts of delay to the scanning line signal, spike noise is added to the overlapping part that occurs in the composite signal, and this is removed together with the overlapping part.
No memory or the like is required for signal synthesis, which simplifies the configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of spike noise removal, and FIG. 3 is an explanatory diagram of another embodiment of the present invention. 2...Transmission beam former, 3...Scanner switch, 4...Transmission/reception circuit, 5...Ultrasonic probe array, 6A, 6B, 6C, 6D...Electronic focus circuit, 7B, 7C, 7D...Delay circuit , 8...
...Focal zone changeover switch, 9,15
A, 15B, 15C, 15D...BPF, 13...
...Write control logic circuit.

Claims (1)

[Claims] 1 In the signal editing circuit of an ultrasound diagnostic device, which synthesizes echo signals so as to receive echoes while switching the focus in order to obtain echo images with good resolution over the entire area, scanning line signals with different focuses are A plurality of electronic focus control means that perform phasing and summation, a plurality of delay means that give different delay times to the output signals from the electronic focus control means, and a plurality of delay means that switch the output signals of the delay means to form one scanning line data. a switching means for compositing;
A signal editing circuit comprising write control means for controlling writing to a frame memory so as to restore continuity by excluding signals in overlapping areas of the combined scanning line signals.