KR0162735B1 - Ultrasonic Signal Processing Equipment - Google Patents

Abstract

In the ultrasonic signal processing apparatus, each received signal obtained by the receiving processing means is digitalized by sampling at a sampling clock with a frequency higher than the Nyquist frequency with respect to the highest frequency of the band of the received signal. The frequency of the digital received signal waveform is shifted by multiplying the reference signal of the corrected frequency to accumulate the converted received signal over a longer time period than the sampling period, and the accumulated signal is subjected to the ultrasonic beam in one direction. The sampling clock is processed at a low clock frequency, and a plurality of ultrasonic receiving beams are formed from the received signals obtained by each ultrasonic vibrator after one ultrasonic wave transmission without using a plurality of circuits.

Description

Ultrasonic Signal Processing Equipment

1 is a diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the first embodiment.

2 is a diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the second embodiment.

3 is a time sequence chart of a second embodiment.

4 is a diagram showing an example of the configuration of the first waveform converting means.

5 is a diagram showing an example of the configuration of the accumulating means.

6 is a diagram showing an example of the configuration of the second waveform converting means.

7 is a diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the third embodiment.

8 is a diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the fourth embodiment.

9 is a diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the fifth embodiment.

10 shows an example of a cumulative waveform diagram.

11 is a block diagram of a sixth embodiment.

Fig. 12 is a diagram showing the configuration of main parts of an ultrasonic signal processing apparatus according to the prior art.

13 is an explanatory diagram of a plurality of reception beam forming examples of the ultrasonic signal processing apparatus according to the conventional example.

14 is a time sequence chart in the third embodiment.

* Explanation of symbols for main parts of the drawings

100: ADC 101: first waveform conversion means

102: cumulative means 103: multi-directional delay processing means

104: ultrasonic vibrator 105: addition means

106: envelope conversion means 107: DSC

108: display means 109: sampling signal generating means

110: digital reference signal generating means 112,113: digital multiplier

114: latch 119: delay means

121: phase correction signal generator 122: delay control means

126: CFM processing means 127: Doppler (DP) processing means

Sck: Sampling Clock

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing method and apparatus, such as an apparatus for nondestructive inspection of an object by ultrasonic waves or an ultrasonic apparatus for use in medical diagnosis, and more particularly, to an ultrasonic signal processing apparatus suitable for digitalization.

A conventional ultrasonic receiver is composed of analog delay means, an adder, and the like, and after transmitting ultrasonic waves to an inspection object, as shown in FIG. 12, a plurality of reflected waves from the inspection object are arranged. Received by the ultrasonic vibrator 104, each received signal is input to the receiving processing means 132, the mutual delay time difference of the received signal received by each ultrasonic vibrator is adjusted, the output of the receiving processing means 132 is added The receiving beam 131 is formed by the receiving beam forming means 129 which is added by the means 105 and forms the receiving beam, and electrically scans the receiving beam to obtain a tomogram of the inspection object.

In the process of forming the reception beam, in order to form a good reception beam, it is necessary to increase the delay accuracy of the reception processing means 132. Therefore, the problem of the analog circuit due to digitalization (component deviation, temperature drift) ), There are various attempts to solve the problem. However, in the case of simply digitizing, a medical ultrasound apparatus using ultrasonic waves having a frequency of about 1 MHz to 20 MHz requires a high speed ADC (analog-to-digital converter) of 100 MHz or more, and a method of realizing a low speed ADC has been devised.

As an example, there is an apparatus proposed by the present applicant in Japanese Patent Laid-Open No. Hei 6-313764, "Ultrasonic Signal Processing Device." The apparatus digitalizes a received signal, multiplies the digitalized received signal by two reference signals having a 90 ° phase difference while having a center frequency of the received signal, converts the received signal into a complex signal, and extracts a low frequency component, The phase difference between the signals obtained by the element (ultrasound vibrator) is corrected by phase rotation, and the time is delayed.

In addition, Japanese Patent Application Laid-Open No. 4-223289 (corresponding Japanese application of USP 4,983,970) digitizes a received signal, and has two reference signals having a 90 ° phase difference while having a center frequency of the digitized received signal and the received signal. The method of multiplying and converting into a complex signal to extract low frequency components, delaying the time difference between signals obtained from adjacent elements by time delay, and rotating the phase is described. Japanese Patent Application Laid-Open No. 2-4355 (corresponding to Japanese Patent Application No. 4,886,069) in which a digital signal is received by an ADC installed in parallel, low-frequency digitalized signals by a demodulator, and a plurality of phase rotation circuits arranged in parallel A method of forming a so-called plurality of receive beams is described in which each phase is given to a low-frequency signal to simultaneously form receive beams in different directions. In this case, as shown in FIG. 13, the plurality of reception beams refers to the formation of the wave beams 130 in one direction and the reception beams 131a and 131b in the other a and b directions at the same time. . Here, the plurality is not limited to two.

In the prior art, in order to form a plurality of receive beams, as shown in FIG. 13, a plurality of wave beam forming means 129 is required in parallel. Further, depending on the system, the delay processing means required a plurality of circuits in the middle of the water receiving processing means.

For this reason, the conventional technique requires a plurality of circuits in order to form a plurality of receive beams, resulting in a problem that the circuit scale increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems described above in the prior art and to provide an ultrasonic signal processing method and apparatus suitable for forming a plurality of receive beams in a digital method.

Another object of the present invention is to provide an ultrasonic signal processing method and apparatus for forming a plurality of receiving beams without using a plurality of signal processing circuits to process received signals received by an ultrasonic vibrator (element). To reduce.

The ultrasonic signal processing apparatus of the present invention comprises sampling a plurality of ultrasonic vibrators for receiving a reflected ultrasonic signal and a received signal obtained by each of the ultrasonic vibrators sufficiently higher than a Nyquist frequency of the highest frequency band of the received signal. A sampling period is set by a clock, and digitalization means for sampling and digitalizing the received signal, and multiplies the digital reception signal obtained by the digitalization means with a reference signal of a predetermined frequency to complex the digital reception signal, and to perform the digital reception. Accumulating the first waveform conversion means connected to each of the digitalization means one-to-one to shift the frequency of the signal, and the received signal converted by the first waveform conversion means for a time longer than the sampling period. Accumulated one-to-one connected to each of said first waveform converting means for obtaining a cumulative signal And a reprocessing means for processing the accumulated signal at a clock frequency lower than the sampling clock for the ultrasonic beam in one direction, and performing a delay process for forming the received ultrasonic beam in multiple directions by time division processing. A multi-directional delay processing means connected to the accumulating means one-to-one and an adding means for adding the output of each of the multi-directional delay processing means, and after one ultrasonic wave transmission, from the received signal obtained by the ultrasonic vibrator A process of forming a plurality of said ultrasonic wave reception beams is characterized by the above-mentioned.

The ultrasonic signal processing apparatus comprising: means for detecting a phase difference between outputs of the plural directional delay processing means corresponding one-to-one to the adjacent ultrasonic vibrator, and controlling the plural directional delay processing means to It is characterized by having beam forming control means for forming a receiving ultrasonic beam having a phase difference of about zero.

The ultrasonic signal processing apparatus according to the present invention comprises a plurality of ultrasonic vibrators for receiving a reflected ultrasonic signal and a sampling clock sufficiently high than the Nyquist frequency of the highest frequency band of the received signal. Set a sampling period, and multiply the digital reception signal by multiplying the digital reception means by sampling the received signal and digitally multiplying the digital reception signal obtained by the digitalization means with two reference signals having a 90 ° phase difference of a predetermined frequency; A first waveform conversion means connected one to one to each of the digitalization means for shifting the frequency of the digital reception signal, and a length of time longer than the sampling period of the received signal converted by the first waveform conversion means; The first waveform converting means for accumulating and obtaining a cumulative signal A one-to-one accumulation processing means connected to each other, a temporary storage means connected one-to-one to each of the accumulation processing means for temporarily storing the accumulated signal, and controlling the output of the accumulated signal from the temporary storage means. Temporary storage control means, second waveform conversion means connected to the temporary storage means in a one-to-one manner to impart phase rotation to the accumulated signal output from the temporary storage means, and each of the ultrasonic vibrators and the target focus position A one-to-one connection diagram to each of the second waveform conversion means for providing a delay means to the output of the second waveform conversion means to correct the propagation time difference of the ultrasonic waves by the distance difference between Adding means for adding an output of the delay means, and means for converting the output of the adding means into an envelope signal, wherein the temporary storage means is provided in one ultrasonic wave wave. In order to form a plurality of receiving ultrasonic beams in different directions, a process of controlling the output of the cumulative signal in the temporary storage means to form the means ultrasonic beam is performed by time division processing to form ultrasonic beams in the plurality of directions. It is characterized by performing a process.

The ultrasonic signal processing apparatus comprising: means for detecting a phase difference between outputs of the delay means corresponding one-to-one to the adjacent ultrasonic vibrator, wherein the temporary storage means, the second waveform converting means, and And a beam forming control means for controlling the respective delay means to form a receiving ultrasonic beam having the phase difference almost zero.

Moreover, the ultrasonic signal processing apparatus of the present invention includes a plurality of ultrasonic vibrators for receiving the reflected ultrasonic signal, and the received signals obtained by the respective ultrasonic vibrators at frequencies sufficiently higher than the Nyquist frequency of the highest frequency band of the received signal. A digital signal is obtained by setting a sampling period by a sampling clock, multiplying the received signal by digitizing the received signal, and multiplying the digital received signal obtained by the digitizing means with two reference signals having a 90 ° disparity between a predetermined frequency; A first waveform conversion means connected to each of the digitalization means one-to-one, and the received signal converted by the first waveform conversion means to complex the signal and shift the frequency of the digital reception signal; The above-mentioned angles which accumulate for a sufficiently long time length to obtain a cumulative signal Accumulation processing means connected one-to-one to one waveform converting means, and propagation of ultrasonic waves by the distance difference between the ultrasonic vibrator and the target focus position to form a plurality of different receiving ultrasonic beams for one ultrasonic wave wave. Delay means connected one to one to the cumulative processing means for correcting the time difference and giving a delay time to the cumulative signal to form a receiving ultrasonic beam in the other direction by time division processing, and an output of the delay means. Second waveform converting means connected one-to-one to each delay means for imparting phase rotation, adding means for adding the output of each second waveform converting means, and converting the output of the adding means into an envelope signal. And a plurality of ultrasonic receiving beams from the received signals obtained by the respective ultrasonic vibrators after the ultrasonic wave is transmitted once. It has a characteristic that does.

In the ultrasonic signal processing apparatus, between the output of each of the second waveform converting means and having an amplitude, and between the outputs of the second waveform converting means corresponding one-to-one to the adjacent ultrasonic vibrator. And means for detecting the phase difference, and having beam forming control means for controlling the respective second waveform converting means and the delay means to form a receiving ultrasonic beam having the phase difference almost zero.

The following example shows that "the sampling period is set by a sampling clock of a high frequency sufficient for each of the band maximum frequencies of the received signal than the Nyquist sampling frequency". For example, a sampling clock of sufficient high frequency is a frequency sufficiently high with respect to the Nyquist sampling frequency with respect to the upper limit frequency of the band of 7.5 MHz when the center frequency of the ultrasonic wave is 5 MHz and the upper limit of the band is 7.5 MHz. For example, 25 MHz.

An example of "accumulating over a length of time longer than the sampling period" is as follows. For a length of time longer than the sampling period, the sampling period is 40 ns at 25 MHz, and the cumulative processing is performed at a time of 80 ns or more when accumulating (adding) two or more times.

An example of "processing a received signal at a frequency clock lower than a sampling clock for a single ultrasonic beam" is shown next. In the case where the received signal is signal-processed every 40 ns for one ultrasonic beam, and the two ultrasonic beams are formed by time division, the time interval of the received signal signaled in the process of forming one ultrasonic beam is 80 ns ( 12.5 MHz), and signal processing is performed at a frequency clock of half of 25 MHz.

The following example shows that the baseband signal is dropping at a frequency sufficiently lower than the center frequency of the first received signal. For example, if the center frequency of the received signal is 5 MHz and the band upper limit signal component is 7.5 MHz, the baseband signal obtained after mixing using the reference signal of the center frequency 5 MHz is 5 MHz of the received signal. The component is shifted to the low frequency side at 0 MHz and the 7.5 MHz component at 2.5 MHz, respectively, and is falling to a sufficiently low frequency compared to the center frequency of the first received signal.

According to the present invention, there is a remarkable effect that it is possible to realize an ultrasonic signal processing apparatus suitable for forming a plurality of receiving beams in a digital system, particularly an ultrasonic signal processing apparatus capable of forming a plurality of receiving beams without using a plurality of signal processing circuits. have.

In the received signal processing circuit in the ultrasonic signal processing apparatus of the present invention, since the Nyquist sampling frequency of the received signal dropped to the baseband falls at a low frequency, the time interval of data generation for one receive beam becomes long. The sampling frequency for this data generation can be lowered. When this sampling frequency is actually 1 / m of the sampling frequency applied to the ADC, the order of data processed in the time direction in one received signal processing circuit can be changed, and m beam data can be processed by time division. Therefore, in the multi-directional delay processing means, signal processing for forming a plurality of receive beams by time division processing in one receive signal processing circuit can be performed, and a plurality of receive beams can be obtained without increasing the circuit size of the receive beam forming means. Can be formed.

Best Mode for Carrying Out the Invention Embodiments of the present invention will be described in more detail below with reference to the drawings.

1 is a block diagram showing the configuration of main parts of the ultrasonic signal processing apparatus according to the first embodiment of the present invention. Each received signal received by the plurality of ultrasonic vibrators 104 is processed by an amplifier or a variable amplifier, an analog filter, an analog filter of variable bandwidth, or the like, and is input to the reception processing means. Here, the reception processing means is composed of an ADC 100, a first waveform conversion means (Digital Mixer) 101, an accumulation means 102, and a multi-directional delay processing means 103. 1, 2, 7, 8, 9, and 11 show examples of four channels for the sake of simplicity.

Each received signal input to the reception processing means configured as shown in FIG. 1 is digitally converted by the ADC 100 constituting the reception processing means. The sampling clock Sck set by the ADC is generated by the sampling signal generating means 109 and is commonly input to the ADC sampling clock input terminal of each channel. As a matter of course, a sampling signal generating means may be provided for each substrate (for example, 20 channels of receiving processing circuits are LSI-equipped for each channel). However, the sampling clock is synchronized on all channels.

In addition, there is no problem even if the receiving processing circuit is LSIized and outputs the sampling clock from the LSI of each channel. Here, a plurality of identical reception processing circuits are arranged in parallel in the channel, and each reception signal is input and signal processed from each ultrasonic vibrator, but a reception processing circuit in which one reception signal is input is called a channel.

It is known that the sampling frequency of the ADC can be reproduced if the sampling frequency is more than twice the maximum frequency of the band of the received signal. Next, it is known that the sampled received signal has a first waveform converting means. In the present invention, the signal from each ultrasonic vibrator is sampled at a sufficiently high frequency. Next, the sampled received signal is input to the first waveform converting means 101, and multiplied by the digital reference signal (center frequency ωs) in the digital reference signal generating means 110 so that the waveform of the received signal is a difference frequency component. The signal is converted into a complex signal consisting of a sum frequency component.

In the digital reference signal generating means 110, the digital reference signal is also input to each channel in common. 4 shows a specific example of the first waveform converting means 101 (Digital Mixer).

In the example shown in FIG. 4, the received signal converted into m-bits in the ADC 100 is divided into two, and cos (ωs ^t ) is shifted in one direction by the digital multiplier 112, and sin in the other direction by the digital multiplier 113. Multiply by (ωs ^t ) Ωs is the center frequency of the received signal. The received signal is converted into a complex signal by the signal shown in FIG. 4, and the complex signal is a signal component of a baseband having a difference frequency component (difference frequency ωs-ωs = 0), and a sum frequency component (sum frequency ωs + ωs). = 2ωs). The output signals (imaginary part and real part signal) shown in FIG. 4 are input to the accumulation means 102. As shown in FIG. As shown in FIG. 10, since the signal components of the baseband are separated at a sufficiently low frequency compared to the center frequency of the first received signal, even if the sampling frequency is the same as the sampling frequency of the ADC, the Nyquist sampling frequency is sufficient for the baseband. It becomes satisfactory sampling (oversampling) and can add (accumulate) the received signals sampled in time series. A specific example of cumulative chatter is shown in FIG.

The complex received signals inputted by (m + 4) bits are held in sequence at each latch 114, and the adder 115 adds three consecutive data in sequence of the circuit output signal shown in FIG. . If the maximum amplitude is input to the ADC, the number of bits naturally increases to become (m + 6) bits. The addition of the received signal cancels the quantization noise and the white noise of the input noise, and the signal is almost tripled and the noise is multiplied by three times, so that the S / N is improved by 3 dB. The number of additions (COUNT) in the leakage means is determined by the sampling frequency (f _s ) and the bandwidth (BW) of the receiving frequency.

COUNT ≤ (f _s / BW) ..... (Equation 1)

Becomes If the condition of Equation 1 is satisfied, the envelope of the received signal is reproduced.

The structure shown in FIG. 5 is a structure of the accumulating means which has a rectangular superposition filter characteristic in order to add and output three successive received signals sequentially. In order to reduce unnecessary frequency components of the sum frequency components, two stages of the configuration of FIG. 5 are provided in series, a triangular overlap is added in addition (cumulative) of the received signal, and the number of additions is adjusted to the front and rear stages. Various methods are conceivable, such as form superposition. In either method, the provision of various adders can be realized. When the output data of the first waveform converting means (digital multiplier) 101 of FIG. 2 is represented by Di (i is the number of the sampling clock signal), (D1 + D2 + D3 + D2 + D3 + D4 + D3 + D4 + D5). ) = (D1 + 2D2 + 3D3 + 2D4 + D5). The coefficient of Di is 1, 2, 3, 2, 1 showing triangular overlap.

The baseband signal of the received signal is obtained by the accumulating means of FIG. Various delay processing is performed using this baseband signal. Here, the multi-directional delay processing means 103 corrects the time difference in which the ultrasonic wave propagates the distance difference between the target focus position and each ultrasonic vibrator by time, phase, or the like, and adds it by the adding means 105 to fit the wavefront of the reflected ultrasonic wave. A signal is formed by adding the received signals by each ultrasonic vibrator to obtain an envelope of the received signal by the envelope converting means 106 to form a receive beam. The beam is scanned and displayed on the display means 108 by the DSC (digital scan converter) 107.

2 shows an example of the configuration of the multi-directional delay processing means 103. In this configuration example, the reception signal processed by the accumulation means 102 is once stored in the temporary storage means 117, and the same reception signal Ri is received by the temporary storage control means 120 in a plurality of reception beams. This is an example in which the reception signal Ri necessary for formation of the reception beam is stored for output for use in the formation, and is output from the temporary storage means to form a plurality of reception beams in time series.

Next, a sequence of multiple beam formation according to the second embodiment of the present invention will be described. Example of a sequence of forming a plurality of ultrasonic receiving beams from the received signals obtained by the respective acoustic wave vibrators forming the receiving wave aperture after one ultrasonic transmission in FIG. 3 and forming the receiving beams in two different directions. Indicates. In FIG. 3, the output timing of each processing means is shown by taking the fourth channel as an example, but the same applies to the other channels. The sampling clock Sck signal is output to the H point (sampling clock of ADC) of FIG. The ADC operates sampling at the time of rising (arrow) of the sampling clock Sck. The whole system operates at the system clock synchronized with the sampling clock Sck. At the time of the arrow, the received signal is sampled by the ADC, and the signals converted into baseband and sum frequency components by the first waveform converting unit 101 are converted into D1, D2, D3, ... (each If the amplitude is a received signal quantized for each rise of the sampling clock signal, and the signal Di converted into the baseband and sum frequency components in the example of FIG. 4 is represented by (m + 4) amplitude, the accumulation means 102 For example, in the case of the configuration of FIG. 5, the output B of the accumulating means 102 becomes (D1 + D2 + D3) = R1 (D2 + D3 + D4) = R2, ... and the sampling clock signal. The reception result Di added in three is prepared and the addition result added is output.

The outputs R1, R2, R3, ... Ri of the accumulating processing means become a baseband signal substantially as a result of the sum frequency component being suppressed by the filtering. This baseband signal is stored in the temporary storage means 117. In this case, it is conceivable to form reception beams in different directions for every one system clock signal. For example, a reception beam (a beam) in the even-numbered a direction and a reception beam (b-beam) in the odd-numbered direction b are respectively formed. The first received signal of beam a of the reference channel (here, the center channel among the plurality of channels constituting the receiving aperture) is R2, the next received signal of the reference channel is the first received signal for the b beam, The received signal to be added to the first received signal for this b-beam is called R1. Here, the order of the reception signal used for beam formation is reversed to R2 and R1 with respect to the row of the reception signal of the accumulation means 102 output. Therefore, the output signal of the cumulative means is stored in the temporary storage means 117, for example, the received signal of R2 is read from the temporary storage means 117 in the fourth system clock signal, and R1 in the next system clock signal. By reading the received signal, the received signal necessary for forming the received beam is taken out from the temporary storage means in the required order. The phase correction signal generation means 121 adds the phase correction data aF1 for forming the a beam at the focus stage to the received signal output from the temporary storage means. In this way, the signal processing necessary for shaping the reception beams in each direction is performed, and the data Ri is sequentially output from the temporary storage means to maintain the order of the respective channel signals and the order of correcting the delay of the signals, by the adding means 105. In addition, an envelope is obtained by the envelope converting means 106, and the plurality of reception beams finally obtained by time division by the DSC 107 are displayed on the display unit 108 simultaneously.

2 and 3, the output order of the temporary storage means is changed to the output order of R2, R1, R4 ... with respect to the output order of the output C of the cumulative processing means 102, and is outputted. The phase correction signal generating unit 121 gives R2 phase correction data aF1 for forming the a-beam of the first stage of focus.

Next to R1, phase correction data bF1 of the B beam of the first stage of focus is given. Phase rotation is processed by the second waveform converting means 118, and the first received signal a1 of the a beam, the first received signal b1 of the b beam, and the second received signal a2 of the a beam, It is output in the following order. The output signal is output in order to the delay means 119 such as a memory. In performing the delay time processing, the delay means 119 reads the received signals of a1, b1, a2, ... in accordance with the output of the received signal of the channel delay means, which is a reference, to impart a time delay. For example, in FIG. 3, the time delay for two system clocks is given to the received signal, and the output of the delay means 119 is the first received signal forming a beam of the reference channel (second channel). Since a1 is output at the time of outputting the sixth sampling clock signal, in this channel (fourth channel) described so far, a1, which is the first of the received signals forming the a beam, is also output at the sixth sampling clock signal. The output a1 of the reference channel (second channel) is also added.

Therefore, it can be seen that the time delay can be realized by two clocks by outputting from the delay means by delaying two clocks. Here, in the focus stage, the focus data (data read from the delay means (memory) and phase rotation data) are changed with time in order to dynamically change the focus distance and obtain a good focus at the entire depth. The interval of the focus data is defined as "stage". In this way, the multi-directional delay processing means 103 processes the sampled received signal by time division, and outputs a received signal for forming a plurality of receive beams. The added data is added to all the channels constituting the water wave aperture by the adding means 105, and the above-described signal processing contents are repeated. The signal indicative of the multiple reception beams thus obtained is once stored in the DSC (Digital Scan Converter) and simultaneously displayed on the display means as the multiple reception beams.

Further, in the ultrasonic signal processing apparatus which performs signal control processing and signal processing by a personal computer, digital processing is performed for processing for receiving beams and processing for DSC. In addition, the sequence shown in FIG. 3 normally performs timing adjustment by a latch or the like due to the limitation of the circuit operation speed of the LSI. However, the sequence is shown as an abnormal operation for explanation of the principle.

Here, looking at the data formation period of the received signal forming one reception beam, for example, the data of the a beam is a1, a2, a3, but the data formation period is 2 clocks of Sck, twice the ADC sampling period. It can be seen that the signal processing speed forming one reception beam is at a low frequency.

6 shows an example of the configuration of the second waveform converting means 118. Input signal phase rotation for the (real part, imaginary part) (Ø _n) is a 90 ° phase signal (cosØ _n, sinØ _n) shifted by multiplying each of the input complex signal by the multiplier 116, the adder 115 Adds the outputs of the two multipliers to perform phase rotation. At this time, the phase rotation amount data is input to each channel by the phase correction signal generator 121 of FIG. As illustrated in FIG. 3, as described above, one receiving beam is focused indefinitely, but the focus positions of the four sampling clock signals are replaced at the output time points of the four sampling clock signals. Shall be.

aF1 means data of the first stage of focus of the a beam. The phase rotation data is aF1 at the output point of the fourth sampling clock signal, the b beam is focused at the output point of the fifth sampling clock signal, bF1 is focused at the first stage, and the beam is focused at the output point of the sixth sampling clock signal. At the output stage of the aF1 and the seventh sampling clock signals, the focus positions are switched at the output stage of the bF1 and eighth sampling clock signals at the first stage of the b beam, and the phase is the same as the aF2 at the second stage of the focus of the a beam. The focus data used for rotation is changed and controlled.

Next, a third embodiment of the present invention will be described.

7 shows another configuration example of the multi-directional delay processing means 103, and is an example in which the delay means 119 is provided at the front end of the second waveform conversion means 118. As shown in FIG. FIG. 14 shows a process of forming a plurality of ultrasonic receiving beams from received signals obtained by each ultrasonic vibrator forming a receiving aperture after one ultrasonic wave transmission by the configuration shown in FIG. 7, and forming receiving beams in different directions. The sequence for doing so is shown (the method of notation is the same as FIG. 3). In FIG. 14, the output timing of each processing means is shown using the fourth channel as an example, but the same applies to the other channels. As shown in Fig. 14, the output means of the accumulating means is delayed to select the received signal to form the received multiple beams and output to the second waveform converting means.

The outputs R1, R2, R3, ... Ri, ... of the accumulating processing means are stored in the delay means (memory) 119. The delay means 119 corrects the delay time with the reference channel (the second channel) when reading data, and then receives the reception beam (a beam) in the right-most to a-direction of the system clock Sck in the odd order. A reception beam (b beam) in the b direction is formed. If a time delay of two system clocks is required for a reference beam (a second channel) and four system clocks are required for a b beam for a reference channel (second channel), as shown in FIG. The delay is read by the clock time, the b beam is read by delaying the R1 by the time of four system clocks, and a delay is realized for each received beam. The result is obtained by multiplying the delayed signal by the weft correction data and performing phase correction (phase rotation), and performing a delay processing with good precision. The received signals sequentially output from the delay means (memory) 119 are added by the adding means 105 while maintaining the order of formation of the reception beams of each channel, the order of the received signals of the delay-corrected channels to be added, An envelope is obtained by the envelope converting means 106, and a plurality of reception beams obtained by time division by the DSC 107 are displayed on the display unit 108 simultaneously. In this way, after one ultrasonic wave transmission, a process of forming a plurality of ultrasonic receiving beams from the received signals obtained by the respective ultrasonic vibrators forming the receiving aperture can be performed, and a plurality of receiving beams can be formed by time division in one channel. This operation is repeated and an image is obtained by scanning a beam. In addition, the read timing of data from the delay means (memory) is controlled by the delay control means 122.

8 illustrates the configuration of the fourth embodiment in which the unnecessary response of the ultrasonic beam is reduced by superimposing on the received signal with reference. An overlap multiplier 124 is arranged in each channel at the output of the multi-directional delay processing means 103. The superimposition data is input to each channel by the superimposition data generating means 123, so that a good reception beam with a small unnecessary response is formed.

9 shows the configuration of the fifth embodiment. In this embodiment, the focal blur caused by the unevenness of sound velocity distribution in the living body with respect to the preset focus data is compared to the phase multiplication or cross-correlation between the delayed complex received signals of each channel and the respective channels. Obtained by the phase error detecting means 125 for detecting the phase difference, and feeding back the time difference converted by the phase difference and the phase difference to the receiving beam forming control means 111, correcting the reception beam forming control conditions to correct the focal blur. do.

11 shows the configuration of the sixth embodiment. In the Doppler process and the CFM (color flow mapping) process, which is a two-dimensional color display of blood flow, the received signal is dropped to the baseband and processed. In the signal processing method of the present invention, since the received signal is dropped to the baseband, the movement of organs other than the blood flow due to MTI (fixed material removal filter: respiration, movement of the heart, etc.) is low frequency near zero frequency and artifacts. Therefore, the blood flow can be detected by the CFM processing means 126 and the Doppler (DP) processing means 127 through the high pass filter to remove the received signal and the low frequency component.

Although the formation of a plurality of receive beams has been described above, in the case of forming a single receive beam, the signal processing after the cumulative processing may be processed by a system clock of 1 / m or may be processed as it is by the system clock of the same speed as the ADC sampling clock. Does not matter. The change of the signal processing speed after this cumulative processing can be realized by changing the control data of the beam forming control means.

Incidentally, in the above embodiment, for the sake of simplicity, a sector scan in which a reception processing circuit (receive channel) is connected to the ultrasonic vibrator one-to-one (in sector scan, the water wave diameter is formed by all ultrasonic vibrators) is one example of the present invention. Although demonstrated, this invention is not limited to this of course. In addition to the sector scanning, for example, an ultrasonic detector such as linear or convex, the above-described embodiments are similarly applied to an ultrasonic apparatus that requires a function of selecting a device (ultrasound vibrator) that performs the wave (wavelength selection). Applicable In the present invention, if the number of the receiving processing circuits is the number of the ultrasonic vibrators forming the receiving aperture, the process of forming a plurality of ultrasonic receiving beams from the received signals obtained by each ultrasonic vibrator forming the receiving aperture after one ultrasonic wave transmission. I can do it.

Claims (7)

Digital reception by multiplying a plurality of ultrasonic vibrators for receiving the reflected ultrasonic signal, digitalization means for sampling and digitizing the received signals obtained by the respective acoustic wave vibrators, and digital reception signals obtained by the digitalization means and reference signals of a predetermined frequency. A first waveform conversion means connected to each of the digitalization means one-to-one, and the received signal converted by the first waveform conversion means to complex the signal and shift the frequency of the digital reception signal; Cumulative processing means connected one-to-one to each of the first waveform converting means, which accumulates for a longer time to obtain a cumulative signal, and processes the cumulative signal at a clock frequency lower than the sampling clock by accumulating the cumulative signal. The above-mentioned angles which perform the delay process for forming the receiving ultrasonic beam of a multiple direction by time division process. A multi-directional delay processing means connected to the accumulating means one-to-one and an adding means for adding the output of the multi-directional delay processing means, and after one ultrasonic transmission, from the received signals obtained by the respective ultrasonic vibrators And an ultrasonic signal processing apparatus for performing a process of forming a plurality of said ultrasonic reception beams. The apparatus according to claim 1, further comprising means for detecting a phase difference between the outputs of the multidirectional delay processing means corresponding one-to-one to the adjacent ultrasonic vibrator, and controlling the multidirectional delay processing means to substantially reduce the phase difference. An ultrasonic signal processing apparatus having control means for forming a receiving ultrasonic beam of zero. A plurality of ultrasonic vibrators for receiving the reflected ultrasonic signals, digitalization means for sampling and digitizing the received signals obtained by the respective ultrasonic vibrators, and two having a 90 ° phase difference between the digital reception signal obtained by the digitalization means and a predetermined frequency. First waveform changing means connected to each of said digitalizing means in a one-to-one manner, and said first waveform converting means for complexing said digital received signal by multiplying a reference signal and shifting the number of magnetic waves of said digital received signal; Cumulative processing means connected to each of the first waveform conversion means one-to-one to accumulate the converted received signal for a time length longer than the sampling period, and to accumulate the temporarily stored signal; Temporary storage means connected one to one to each of the accumulation processing means, and the accumulation from the temporary storage means. Temporary memory control means for controlling the output of the call, second waveform converting means connected one-to-one to each temporary memory means for imparting phase rotation to the accumulated signal output from the temporary memory means, and the ultrasonic vibrator Delay means connected one-to-one to each of the second waveform converting means for giving a delay time to the output of the second waveform converting means to correct the propagation time difference of the ultrasonic wave due to the distance difference between And adding means for adding outputs of the delay means, and means for converting the output of the adding means into an envelope signal, wherein the temporary memory control means receives ultrasonic waves in a plurality of different directions corresponding to one ultrasonic wave wave. Time-dividing processing of controlling the output of the accumulated signal in the temporary storage means to form the received ultrasonic beam to form a beam And a process for forming an ultrasonic beam in a plurality of directions. 4. The apparatus according to claim 3, further comprising means for detecting a phase difference between outputs of the delay means corresponding one-to-one to the adjacent ultrasonic vibrator, wherein each of the temporary storage means, each of the second k waveform conversion means, and each of And a beam forming control means for controlling a delay means to form a received ultrasonic beam having the phase difference almost zero. A plurality of sound wave oscillators for receiving the reflected ultrasonic signals, digitalization means for sampling and digitizing the received signals obtained by the respective ultrasonic oscillators, and two having a 90 ° phase difference between the digital reception signal obtained by the digitalization means and a predetermined frequency. First waveform converting means connected to each of the digitalizing means one-to-one to multiply the digital received signal by multiplying the two reference signals and shift the frequency of the digital received signal; and by the first waveform converting means Cumulative processing means connected to each of the first waveform conversion means one-to-one to accumulate the converted received signal over a time length longer than the sampling period, thereby obtaining a cumulative signal; The distance difference between each ultrasonic vibrator and the target focus position is used to form a receiving ultrasonic beam in a different direction. Delay means connected to the accumulation processing means one-to-one to correct the propagation time difference of the ultrasonic waves and to give the accumulation means a delay time for forming the received ultrasound beam in the other direction by time division processing; Second waveform converting means connected one-to-one to the delay means for imparting phase rotation to the output of the delay means, adding means for adding an output of each of the second waveform converting means, and an output of the adding means. Means for converting into an envelope signal, and performing a process of forming a plurality of said ultrasonic receiving beams from said received signal obtained by said each ultrasonic vibrator after one ultrasonic wave transmission. The ultrasonic signal processing apparatus according to claim 5, further comprising means for applying amplitude overlap to the output of each of the second waveform converting means. 6. The apparatus according to claim 5, further comprising means for detecting a phase difference between the outputs of the respective second waveform converting means in a one-to-one correspondence to the adjacent ultrasonic vibrator, wherein the second waveform converting means and the delay means respectively. And beam forming control means for controlling a to form a receiving ultrasonic beam having the phase difference almost zero.