SU1439486A1 - Acoustic image system - Google Patents

Abstract

The invention relates to a measurement technique and can be used to visualize the internal structure of opaque objects. The purpose of the invention, better resolution, is achieved by improving the accuracy of setting phase shifts between the detection signals by using an analog system for controlling phase shifters. The acoustic imaging system is an electronic scanning system of the acoustic antenna array 1.1-1.p. With synchronous detectors 2.1-2.P, 4.1-4.2p delay lines, generator 7 of sinusoidal voltage, control unit 8, D-triggers 11.1-ll.n there is a definite relationship between the phases of the probe signals and the reference signals that are used in synchronous detection of the reflected signal. 2 Il. to cl

Description

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The invention relates to a measurement technique and can be used to visualize the internal structure and flaw detection of npoMbiiujjei - nbsb products, as well as in medicine for diagnostics.

The purpose of the invention is to increase the resolution by increasing the accuracy of setting the phase shifts between the detection signals by using an analog system for controlling phase shifters.

Figure 1 is a block diagram of an acoustic image system; Fig. 2 shows timing diagrams for the formation of probe pulses.

The acoustic image system contains n transducers 1.1-1.p ultrasonic phased sieve1 2p synchro detectors 2.1-2.Zn, 2p filters 3.1-3.2p lower frequencies, 2p lines 4.1-4.2p delay, two cyi i- Matora 5.1 and 5.2, arithmetic unit 6, generator 7 sinusoidal voltage, control unit 8, 2p phase shifters 9.1-9.2p, n formers 10.1-10.p pulses, n D- triggers 11.1-11.p, n analog switches 12.1- 12.p.

The acoustic imaging system operates as follows.

The output signal of the sinusoidal voltage generator 7 is continuously fed to phase shifters 9.1, 9.3, 9.5,.,., 9 (2n-1). Each of the phasers can phase-shift the input signal in the range from O to 2. To deflect the main lobe of the radiation pattern (DN) of the transducer 1.1-1 'n by the angle b relative to the normal to the grating surface, phase shifts introduced by the phase-shifters 9.1. 9.3 ,,,., 9, (2n-1) are determined by the formula

Ch. 2 ir d -l, 1. - S 1P U

(one)

50

De 1 is the order number of the phase shifter from a series of phase shifters 9.1, 9.3, 9.5 ,,,, 9, (2n-1); d is the lattice period of the transducers;

HZ D is the ultrasound wavelength in the object under study;

 - the deflection angle of the main lobe of the DN,

 .

Iq

5 20 25 30

Q d

50

;

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The values of the required phase shifts epj are set using control block 8. Phase shifters 9.2, 9.4, 9.6 ,,,., 9.2p shift the signal in phase only by 90 °,

The formers 10.1-10, n pulses convert a sinusoidal signal into a pulse signal, with the state of the logical variable 1 corresponding to a positive half-wave of the sinusoid and the state of the logical variable O to a negative half-wave. Figure 2 shows the timing diagrams for the formation of a probe pulse, the enable signal for the formation of the probe signal of the transducer array 1.1-1, n is a single square 11 pulse at the (2n + 1) -th output of the control unit 8, which is fed to the D input the first D-flip-flop 11 .1, the duration of this single pulsed signal is equal to an integer number of periods of the generator 7 sinusoidal voltage. The durations of the pulse signals of the converters 1.1-1, n of the array are equal to the duration (2n + 1) of the output signal of the control unit 8. D-flip-flops 11.1-11, p send to the output a logic signal present at the D-input only at the moment of transition from O to 1 pulse signal at the C-input. At the time corresponding to the value of the logical variable .1 on the control input of the analog key 12,1-12, n this key is open. Thus, at the output of each of the analog switches 12, 1-12, g: a pulsed electrical signal of the required duration is formed. Ultrasonic phased array transducers 1 convert the electrical signals from the analogue terminals 12.1–12, p, into ultrasonic signals that propagate in the object under study. In this case, an ultrasonic wave with a narrow beam is formed. Ultrasonic echo signals reflected from a defect in the medium or the interface between the media reach transducers 1.1–1. The lattices are converted into electrical signals. The output signal of each of the n converters 1.1-1.n grating is supplied in parallel to two synchronous detectors. Continuous sinusoidal signals of phase shifters 9.1-9.2p are used as detectors of general screens

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synchronous detectors 2.1-2.2ii. The phase shift between the detector signals and the –cooTBeTCTDGHHO signals of the first and second, third and fourth, ..., (2n-1) -th and 2nth synchronous detectors 2 is equal to 90 ° ,. since phase shifters 9.2, 9.4, 9.6, ..., 9.2p shift the signal in phase only by 90 °. Thus, an ultrasonic phased array ultrasonic echo signals are processed. The voltage of the synchronous detector 2 output is proportional to the product of the input and detection signals of the synchronous detector 2. If the ultrasonic grating beam deviates by a certain angle fi relative to the grating normal, -ro lattice transducer 1.1 was phase ahead of the emitted signal (i + 1) It is the phase of the echo signal (1 + 1) th transducer 1. (1 + 1) to the value of the lattice Cfp, where 1 is 1, 2n. The detected signals of the first, third, fifth, ..., (2n-1) -th synchronous detectors 2 are the output signals, respectively, of C2n-1) -th. (2n-3). -Th, ..., of the third, first phasers 9, which were also used to form radiated signals, respectively, of the n-th (p-1) -th, ... first transducer 1 of the array. Therefore, the phase shift between the two input and detection signals of the first synchronous detector 2.1 is equal to the phase shift between the input and detection signals of the third synchronous detector 2.3 and the phase shift between the input and detection signals (2n-1) -th synchronous detector 2.2n-1. Similarly, the phase shifts between the input and detection signals of the second, fourth, ..., 2nth synchronous detectors are equal.

The 3.1-3.2p low-pass filters produce a low-frequency component in the output signals of the corresponding synchronous detectors 2.1-1.2n. The output voltage level of the low-pass filters 3.1-3.2p is proportional to the value of coscf ,, gdes g

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phase shift shift of two detectors 2..2p.

To get 1 I maximum voltage value from output of adders 5.1 to 5.2 output signals of filters 3.1-3.2p are delayed in lines 4.1-4.2p of delay for the corresponding time and. A time delay of 10 for the corresponding pair of delay lines (LZ) is determined by the formula

dsinS. one : :;

(2)

where 1 is the order number of the LZ pair from the p Yes and LZ pairs: 4.1 and 4.2, 4.3 and 4.4, ..., n, 4. (2n-1) and 4.2p,

d is the lattice period of the transducers;

b - the angle of deviation of the main lobe of the DN with respect to the normal to the lattice C - the speed of ultrasound in the object under study.

The determination of the values of the required time delays is carried out by control block 8. In the first adder 5.1, the signals from the outputs of the first, third, ..., (2n-1) -th delay lines 4 are summed. The second adder 5.2 summarizes the output signals of the second, fourth, ..., 2nth 4 delay lines. Ari | 1matic block 6 processes the received two sums using the following formula

and

this

(3)

0 where is the value at the output of the arithmetic unit 6; Uf. - the value of the output of the first adder 5.1; and - the value at the output of the second-adder 5.2.

The output of the arithmetic unit 6 is a video signal that can be used in a cathode-ray tube or in a display to visually indicate the points of an object from which ultrasound is reflected.

Pulse shapers 10.1-IO.n are implemented on the basis of type 597CA1 comparators, one input of which is grounded, and the other input is fed by a sinusoidal signal. As a D-flip-.: Moat 11.1-11. P used integrated circuits of the type K155TM2, in each

the casing of which there are two D-triggers each. Analog keys 12.1-12.P are assembled on the basis of K590KN2 type microcircuits, containing on the key of the key. Phs: 1, 3, 3, 3, 2 p low frequencies are implemented according to well-known schemes of phyters of low frequencies of the first order. Adders 5.1 and 5.2 are constructed according to the inverting scheme. The arithmetic unit 6 is assembled according to the vector length calculation scheme. The generator 7 of sinusoidal voltage is assembled according to the quartz circuit of this generator. Phase shifters 9.1-9.2p are built according to the bridge phase-shifter scheme. The control unit 8 is made in the form of a microprocessor module based on the K580IK80 microprocessor. Synchronous detectors 2.1-2.2p are sold according to a known scheme. Ultrasonic phased array is a set of piezoelectric transducers. As delay lines 4.1-4.2, you can use pulse lines with capacitive: accumulation.

Claims (1)

Invention Formula Acoustic imaging system containing n, ultrasonic phased array transducers, 2n. synchronous detectors, 2p low-pass filters, 2p delay lines, two adders, an arithmetic unit, first, second, ..., n-th transducers of the phased array ultrasonic transducers are connected respectively to the inputs of the first and second, third and fourth, ..., (2n-1) -th and .in-ro synchronous detectors, the outputs of the first, second, ..., 2n-th synchronous detectors are connected respectively to the inputs of the first, second, ..., 2n-second low-frequency devices, the outputs of which are connected according to :: 1 with the inputs of the first, second ,, .., ...,, 2nth delay lines, the outputs of the first, third, ..., (2n-1) th delay lines are connected to the inputs of the first adder, the outputs of the second, , the fourth, ..., 2nth soy delay lines; - dinene with the inputs of the second adder, the outputs of the first and second adders are connected respectively to the first and second inputs of the arithmetic unit, about t l and ch and y p; and in order to increase the resolution, it is equipped with a sinusoidal voltage generator, a control unit, 2n phase shifters, n pulse shapers, n D-triggers, n analog switches, the sinusoidal voltage generator output is connected to the inputs of the first, third, ..., (2n-1) -th phasers, the outputs of which are connected respectively to the inputs of the first, second, ..., ..., n-th pulse formers and to the information inputs of the first, second ,. .., n-th analog keys, the codes of which are connected respectively with the inputs of the first, second, ... ..., n-th transducer ultrasonic phased array, the outputs of the first, second ,, .., n-th pulse formers are connected respectively to the C-inputs of the first, second, ryogo, .. ., n-th D-flip-flops, the outputs of which are connected respectively to the control inputs of the first, second, .. ,, n-th analog switches and with the D-inputs of the second, third, ..., n-th D-flip-flops , the outputs of the first, third, ..., (2n-1) -th phase shifters are connected respectively to the detector 1-1m inputs (2n-1) -g6, (2n-3) th, ..., of the first synchronous detectors and to ix Odes of the second, fourth, ..., 2nth phase shifters, the outputs of which are connected respectively to the detection inputs of 2nth, (2n-2) -th, ..., second synchronous detectors, first, second, ..., n th outputs of the control unit are connected respectively to the control inputs of the first and second, third and fourth, ..., (2n-1) -th and 2nth delay lines, (n-And) -th, (n + 2 ) The second, ..., 2nth control unit is connected respectively to the control inputs of the first, third, ..., (2n-1) -th phase shifters, (2n + 1), and the output of the control unit is connected to D- the entrance of the first D-flip-flop.