JPH0819537A - Received wave phasing circuit of ultrasonic device - Google Patents

Abstract

PURPOSE:To reduce noise in variable bore when digital phasing takes place by nullifying the received signal of a channel out of service while the data of a multiplying means is made zero, adding to the output signal of other channel, and thereby varying the bore to be used according to the focus depth. CONSTITUTION:The operation to vary the bore size according to the focal distance is made using the multiplication data. That is, ch3-ch(n-2) is used for the focal distance F1 and ch2-ch(n-1) is used for F2. while all ch's are used for F3. If a triangular weighting is given for the sake of simplification, the weighting factor O is given to F1, F2 and also factor (a) to F3 in case ch1 is used. When ch2 is used, on the other hand, weighting factor O is given to F1 (a) to F2, and (b) to F3. According to this processing, ch1, 2, (n-1), n are equivalent to out of connection for F1 substantially in the received wave phasing circuit, which permits lessening the bore.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wave receiving and phasing circuit of an ultrasonic device, that is, a wave receiving and phasing circuit of an ultrasonic device for transmitting and receiving ultrasonic waves to obtain a tomographic image It is also referred to as a "phase circuit"), and particularly to a wave rectifying circuit improved by a variable aperture technology that changes the aperture size according to the focus depth.

[0002]

2. Description of the Related Art A conventional variable-aperture technology for a wave receiving and phasing circuit is described in various medical ultrasonic handbooks. For example, it is known that the azimuth resolution Δx at the focus of a rectangular oscillator having a diameter D is Δx = λF / D, where λ is the wavelength and F is the focus distance, and is inversely proportional to the size of the diameter. Therefore, as shown in FIG. 8, a method of obtaining a good beam by changing the aperture according to the focus distance (horizontal axis in the figure) is widely adopted. This method is, for example, as shown in FIG. 8B, n array elements (ch1 to ch
In n), for the short distance, ch4 to ch (n-3) are used to focus on the point of F1. Then, the aperture is increased in order and the focus position is shifted, so that FIG.
As described above, a good ultrasonic beam is obtained. Further, conventionally, regarding the received wave, since it is a phasing circuit using an analog delay line, the aperture has been controlled in an analog manner by a phasing output buffer circuit, a variable gain amplifier and the like. In addition, in a circuit configuration for digitizing and phasing a received signal, as a configuration including a multiplier, for example, Japanese Patent Laid-Open No. 2-2
The technology disclosed in Japanese Patent No. 6548 is known.

[0003]

In the above prior art, when the signal after the received analog signal is erased is digitized by the AD converter, even if the signal of the buffer circuit is set to 0, noise and offset of the circuit will be generated. Occurs,
There is a problem that this is included in the digital signal and converted. Further, the technique related to digital phasing disclosed in Japanese Patent Laid-Open No. 2-26548 describes only the phasing method and does not consider the concept of the variable aperture. The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems in the related art and to reduce noise in a variable aperture in digital phasing. It is to provide a phasing circuit.

[0004]

The above object of the present invention is to make the multiplication data of the digital multiplier zero after digitally converting the received signals from the arrayed ultrasonic transducers, and reset the latch. To control the write / read of the memory, control the sample clock of the AD converter, etc. to zero the received signal of the unused channel and then add it to the output signals of other channels. Is achieved by a wave phasing circuit of an ultrasonic device.

[0005]

In the wave receiving and phasing circuit according to the present invention, after the ultrasonic wave receiving signal is digitally converted, (1) the multiplication data of the channels corresponding to the unused apertures is set to zero, or (2) By setting the latch output to zero, it is possible to output a 0 level signal without noise. Also, (3)
By controlling the write / read clock to the memory, or (4) controlling the sample clock of the AD converter, the output of the memory can be set to 0. Can be output.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a wave receiving and phasing circuit according to a first embodiment of the present invention. As shown in FIG. 1A, the received signal received by the transducers arranged in strips is quantized by the sampling means 1 and written in the memory 2. When the sampling means 1 is an analog-digital converter, the received signals of the respective channels are digitized by the sampling clocks S1 to Sn and written in the memory by the write pulses W1-Wn. Next, the data written in the memory 2 is read by the read pulses R1 to Rn at the timing or address designation for correcting the time difference of each channel, and the delay amount less than the sampling interval is corrected by the delay processing circuit 3, and each channel is read. The ultrasonic beams are formed by matching the phases of and adding by the adder 4.

After that, it is processed by the signal processing circuit 5 and displayed as an ultrasonic image. In order to form a good ultrasonic beam, weighting factors W1-Wn are assigned to each channel.
Is multiplied. This is performed in order to reduce side lobes that occur because the shape of the aperture formed by the transducer array is rectangular. In this embodiment, as described above, the operation of changing the size of the aperture according to the focus distance is performed by using the multiplication data. That is, as shown in FIG. 1B, ch3-ch (n-2) is used at the focus distance F1, ch2-ch (n-1) is used at F2, and all ch are used at F3. For simplicity, let's give a triangle weight,
As shown in FIG. 1C, ch1 gives a weighting coefficient of 0 in F1 and F2, and a coefficient of a in F3. ch2 is 0 in F1, F
2 gives a weight, and F3 gives a weight of b. The same applies hereinafter.

By this processing, in the wave-reception phasing circuit according to this embodiment, in F1, it is equivalent to ch1, 2, (n-1), and n being substantially not connected, and the aperture can be reduced. is there. Others are the same. Next, a wave receiving and phasing circuit according to a second embodiment of the present invention will be described with reference to FIG. The present embodiment is one example of controlling the aperture in the delay processing circuit 3 of the embodiment shown in FIG. In this embodiment, 90
This is an example of a delay method that samples once and performs complex processing. In the case of a complex signal, as shown in FIG.
The phase rotation can be realized by multiplying the real part and the imaginary part signals by the value of and adding them by the crossing as shown in the figure. Note that FIG. 2 shows the basic configuration of one channel, and the phase rotation amount can be set for each channel. Also in the present embodiment, the aperture can be controlled by setting the multiplication data to 0 as in the first embodiment.

FIG. 2B shows an example of the sequence. If ch1 is used from F3, F1, F2
Then, the value of φ1 is usually cos (θ) = if sin (θ) = 0
Although 1 or -1, both sin (θ) and cos (θ) are 0.
By this processing, in F1 and F2, it becomes equivalent to that ch1 is not substantially connected, and the aperture can be reduced. Others are the same. Next, a wave receiving and phasing circuit according to a third embodiment of the present invention will be described with reference to FIG. This embodiment is shown in FIG.
This is a second example of controlling the aperture in the delay processing circuit 3 of the embodiment shown in FIG. In the present embodiment, the roughly quantized sample data is obtained by interpolating a desired point using a sampling function.

In this method, delayed data is generated by multiplying each sampled data of several consecutive points by a coefficient and adding the coefficient. The present embodiment is an example in which interpolation is performed using data of four points. Also in this embodiment, the multiplication data is set to 0 as in the other embodiments described above.
The diameter can be controlled by setting. Figure 3 (b)
Shows an example of the sequence. Similarly to the above, if ch1 is used from F3, the coefficients a, b, c, and d are set to 0 in F1 and F2, and interpolation data a1-3, b1-3, and c1-3 are calculated from F3. , D1-3 are given. By this processing, in F1 and F2, it is equivalent to that ch1 is not substantially connected, and the aperture can be reduced. Others are the same.

Next, a wave receiving and phasing circuit according to a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the received signal is multiplied by the reference wave to shift the frequency. This embodiment is an example of analog frequency shift. In general, AD
The above operation is performed in order to keep the frequency of the converter low. It should be noted that, after digitization, digital frequency shift may be performed, and either case can be dealt with. Also in this embodiment, as in the other embodiments described above, the aperture can be controlled by setting the multiplication data to 0. FIG. 4B shows an example of the sequence.
If ch1 is used from F4, F1, F2, F
In 3, the amplitude of the reference wave is set to 0 or is not input.
The amplitude is set to 1 from F4.

The phase of the reference wave at this time may be the same in all channels, or when the delay of less than the sampling time is made by the phase difference of the reference wave, it is given by the phase difference realizing the delay. The amplitude weight shown in the first embodiment can be realized by the amplitude of the reference wave. By this processing, in F1, F2, and F3, it becomes equivalent to that ch1 is not substantially connected, and the aperture can be reduced. Others are the same. Next, a wave receiving and phasing circuit according to a fifth embodiment of the present invention will be described with reference to FIG. This embodiment is shown in FIG.
This is an example in which the aperture is controlled in the adder 4 of the example shown in FIG.

In digital addition, a latch circuit is inserted to synchronize data. Therefore, even if the delayed data is input to the adder 4 by using this latch circuit having a reset function, the input data of the adder 4 can be held at 0 by keeping the latch in the reset state. In this embodiment, the diameter is controlled by this operation. FIG. 5B shows an example of the sequence.
Assuming that ch1 is used from F3, by setting the latch of ch1 to the reset state in F1 and F2 and operating from F3, it becomes equivalent to ch1 not being connected in F1 and F2, and the aperture is It can be made smaller. Others are the same.

It should be noted that although the description has been given here using the latch of the adder input, the same configuration and operation are possible if the latch is in the signal path. In each of the above embodiments, A
The sample clock of the D converter, the writing to the memory, and the reading from the memory can control the aperture even if control is performed using the entire aperture without considering the aperture change. Further, it goes without saying that even in the example in which the processing of the real part signal is described, it can be applied to the complex processing including the imaginary part. Next, a sixth embodiment of the present invention will be described with reference to FIG. As a delay method using a memory, there are a FIFO method and a method of designating an address. FI
When FO is used, a write pulse is not given to each channel until the required data is first fetched,
After more than the maximum delay time when forming the beam,
Give a read pulse.

In FIG. 6A, the horizontal axis represents the sampling time t, the vertical axis represents each channel, and a, b, c, ... Represent the received signals from the focus point. . This means adding data of the same alphabet for each channel.
FIG. 6B shows the contents of the memory 2 of each channel. W1 of ch1 is applied from t = 5. Therefore, all a's are written at address 1 of the memory of each channel. Here, the maximum delay (in this case, tdmax =
4) After that, that is, by giving a read pulse to each channel from t = 6 and reading them all at once, the phases of all the channels can be aligned. Here, ch1 is t =
Assuming that it is used from 7, the write pulse of ch1 is given from t = 7, and the read pulse is given from t = 8.

At address 1 of the memory of ch1 of FIG. 6 (b),
The value c of t = 7 is written. In ch5, t = 6
Therefore, when ch1 reads address 1 at t = 8, ch5 outputs the value c of address 3. t
= 6 and 7, since the values of FIG. 6B are output except for ch1, only the data of the unused caliber ch1 can be set to 0 until the start of use, and the variable caliber can be realized. Next, RA
The case of using a memory such as M that can specify an address will be described. In the present embodiment, writing is started from address 0 all channels at once, and after reading a maximum delay or more, the start address is set to all channels all at once according to the delay time, and reading is performed. The phase of the channels is adjusted.

In this case, as shown in FIG. 7, the sampling order matches the memory address. In the figure, x indicates that unused data is written. Similar to the above-mentioned embodiments, the same alphabet in each channel is the data to be added. Read out
By setting the address to 5 for ch1 and to 4 for ch2 and starting reading from all the channels simultaneously from t = 6, the delay of all channels can be realized. Here, when performing variable aperture, for example, ch1 is t
Assuming that the data is used from = 7, by setting the address to 7 and applying the read pulse from t = 8, the data of the aperture not used can be set to 0. A variable aperture can be realized by this operation.

It is needless to say that the above embodiment shows an example of the present invention, and the present invention should not be limited to this. For example, the configuration shown in FIG. 7 can also be realized by not applying the sampling clock of the AD converter as in the above.

[0019]

As described above in detail, according to the present invention, it is possible to realize a wave receiving and phasing circuit capable of reducing noise in a variable aperture in digital phasing. Is. More specifically, after the ultrasonic wave reception signal is digitally converted, the multiplication data of the channel which is not used is set to 0, the latch output is set to 0, or the writing / reading clock to the memory is set. Alternatively, since the output of the memory can be set to 0 by controlling the sample clock of the AD converter, it is possible to output a 0 level signal without noise.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration example including a weight multiplication circuit according to a first embodiment.

FIG. 2 is a diagram showing a configuration example of performing phase rotation using a complex signal according to a second embodiment.

FIG. 3 is a diagram showing a configuration example of multiplying and interpolating a coefficient according to a third embodiment.

FIG. 4 is a diagram illustrating a configuration example for performing frequency shift according to a fourth embodiment.

FIG. 5 is a diagram showing a configuration example having a latch according to a fifth embodiment.

FIG. 6 is a diagram showing a configuration example realized by a FIFO according to a sixth embodiment.

FIG. 7 is a diagram showing a configuration example realized by a RAM according to a seventh embodiment.

FIG. 8 is a diagram showing a conventional example.

[Explanation of symbols]

 1 AD converter 2 memory 3 delay processing circuit 4 adder 5 signal processing circuit 6 oscillator

Claims (8)

[Claims] 1. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In the ultrasonic device, which has means for converting a wave signal into a digital signal to give a delay and at least one multiplying means, and adds outputs of respective channels to obtain an ultrasonic wave reception signal, multiplication data of the multiplying means Is set to zero, the received signal of the unused channel is set to zero, and it is added to the output signals of other channels to change the size of the aperture used according to the focus depth. Receiving and phasing circuit of equipment. 2. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In an ultrasonic device having means for converting a wave signal into a digital signal to give a delay and means for multiplying the received signal by a weight, each coefficient of the weight multiplication is set to zero, and an unused channel is received. A wave phasing circuit for an ultrasonic device, wherein the size of the aperture used is changed according to the focus depth by making the wave signal zero and adding it to the output signals of other channels. 3. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In an ultrasonic device having means for converting a wave signal into a digital signal to give a delay, and means for multiplying the received signal by a reference wave to shift the frequency, the amplitude of an unused diameter portion of each of the reference waves Is set to zero, the received signal of the unused channel is set to zero, and by adding it to the output signals of other channels, the size of the aperture used is changed according to the focus depth. Receiving and phasing circuit of ultrasonic device. 4. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In the ultrasonic device, the interpolation calculation means includes means for sampling the wave signal and converting it into a digital signal to give a delay, and means for obtaining a delay amount smaller than the sampling interval of the received signal by interpolation by interpolation calculation. By setting each multiplication coefficient of 0 to 0, the received signal of the unused channel is set to 0, and by adding it to the output signals of other channels, the size of the aperture to be used is changed according to the focus depth. An ultrasonic wave receiving and phasing circuit for an ultrasonic device. 5. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In an ultrasonic device having means for complexly sampling a wave signal to give a delay and means for performing phase matching by multiplying phase rotation data, each amplitude of the phase rotation data of the phase matching means is made zero. By setting the received signals of the unused channels to zero and adding them to the output signals of the other channels, the size of the aperture to be used is changed according to the focus depth. Receiving and phasing circuit. 6. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, the ultrasonic device receiving ultrasonic waves from each of the ultrasonic vibrators. In an ultrasonic device for forming an ultrasonic beam by adding output signals of respective channels and means for delaying by sampling a wave signal, each delay output is provided with a latch, and the latch is put into a reset state. By setting the received signal of the unused channel to zero and adding it to the output signals of the other channels, the size of the aperture to be used is changed according to the focus depth. Receiving wave phasing circuit. 7. An ultrasonic device for transmitting and receiving an ultrasonic beam by controlling the phases of arrayed ultrasonic vibrators to obtain a tomographic image of a subject, wherein at least one of the ultrasonic vibrators is provided. The received signal of is sampled and written to the memory.
In an ultrasonic device having means for giving a delay by reading, by not giving a write pulse or a read pulse for each of the memories, the received signal of an unused channel is made zero and is added to the output signals of other channels. By so doing, the size of the aperture to be used is changed according to the focus depth. 8. An ultrasonic device for controlling a phase of arrayed ultrasonic transducers to transmit and receive ultrasonic beams to obtain a tomographic image of a subject, wherein at least each of the ultrasonic transducers is provided. In the ultrasonic device having means for sampling the received signal and delaying the received signal, the receiving signals of the unused channels are made zero by not supplying the sampling clock of each of the sampling means, and the output signals of the other channels. The wave phasing circuit of the ultrasonic device, wherein the size of the aperture used is changed according to the focus depth.