SU1170342A1 - Ultrasonic scanning device - Google Patents

Abstract

ULTRASONIC SCANNING DEVICE, containing a multichannel emission scheme — reception of ultrasonic signals, including an excitation generator in each channel, a preamplifier and a distribution unit — a collection of ultrasonic signals whose input is connected to the output of the excitation generator, and the output with a preamplifier, and an antenna array of 2n + 1 electroacoustic transducers, each element of which is made in the form of piezoceramic strips of different lengths with a solid electrode on one side, and on the other side there is a t elec The stripes are in the form of strips, the radius of curvature (; "which is determined by the ratio cf R, n where fj is the distance of the i -th electrode from the surface of the n-band, FT is the focal length of the i-roelectrode, UrrI Vcp is the ultrasound velocity in the piezoceramic A bar and a ratch of the medium, respectively, 1 electrodes are connected respectively to the excitation generators and the preamplifiers of the radiation channels of the reception of ultrasonic signals, which are characterized by the fact that, in order to increase the longitudinal resolution, the i electrodes are made flat-bent; Curved side electrodes i izluchakntsey directed towards the surface, and the average width. The electrode ti satisfies the condition -. where is the operating frequency of the piezoisoSO4 chatel formed by the i-th. a flat-bent electrode and a solid electrode.

Description

I I

The invention relates to non-destructive testing and can be used in medical technology, test equipment, flaw detection, as well as other devices in which a co-scanning is performed in a non-mechanical way.

An ultrasonic scanning device containing a multichannel radiation scheme is known — reception of ultrasonic signals and an antenna array of electroacoustic transducers made in the form of piezoceramic strips of different lengths, one side of which is covered with a solid electrode and grounded, and the other one has strip electrodes applied respectively to excitation generators and preamplifiers of emission-reception channels.

The disadvantage of this device is the low resolution, due to diffraction expansion of the ultrasonic beam in the plane, perpendicular to the scanning.

Closest to the invention is an ultrasound scanning device comprising a multichannel emission scheme — receiving ultrasonic signals, including in each channel an excitation generator, a preamplifier and an ultrasonic signal collection distribution unit, whose input is connected to the output of the excitation generator, and the output is with a preamplifier, and an antenna a grid of 2p + 1 electroacoustic transducers, each element of which is made in the form of piezoceramic strips of different lengths with a solid electrode on one side e, and on the other side i are applied electrodes in the form of strips, the radius of curvature of which is determined by the ratio

R

 . . where is the removal of the i-th electrode from

surfaces of the h-th band, F {- focal distance i-ro

electrode,

V and Vf, - ultrasound velocity in the working medium and piezoceramic strip, respectively

{electrodes connected respectively to excitation generators and pred422

amplifiers of channels of receive emission circuitry.

The disadvantage of this device is low longitudinal resolution.

The aim of the invention is to increase the longitudinal resolution.

The goal is achieved

the fact that in an ultrasound scanning device containing a multichannel emission scheme — reception of ultrasonic signals, including in each channel an excitation generator,

the preamplifier and the distribution unit of the collection of ultrasonic signals, the input to 1j is connected to the output of the excitation generator, and the output to the preamplifier, and the antenna array from

2p + 1 electroacoustic transducers, each element of which is made in the form of piezoceramic fringes of different lengths with a solid electrode on one side and on the other

the side is deposited with i electrodes in the form of strips, the radius of which is determined by the ratio

b

where - removal of the 1st electrode

from the surface of the pth band, F, - is the focal distance i-ro

electrode,

V and V. - the speed of ultrasound in the working environment and the piezoceramic strip, respectively,

i the electrodes are connected, respectively, with the excitation generators and channel preamplifiers of the excitation-reception circuit, i the electrodes are flat-bent, the concave side of the electrodes is directed towards the radiating surface, and the average width li; electrodes satisfies the condition

1, Vn / 2, where. - working frequency of the piezoelectric beam formed by a flat-bent electrode

and a solid electrode. The drawing shows a structural diagram of an ultrasonic scanning device, Ultrasonic scanning

the device contains an antenna array of 2p + 1 electroacoustic transducers in the form of piezoceramic

31

strips 1, on the surfaces of which are applied flat-bent electrodes 2-4 and solid electrodes 5, with the flat-bent electrode 2 on the nth piezoceramic strip applied at a distance E from its working surface, and the rest are shifted to the back by i / i a multichannel radiation circuit — receiving ultrasonic signals, including in each channel an excitation generator 6, a preamplifier 7 and an ultrasound signal collection distribution unit 8 j, flat-concave electrodes 2–4 are connected to an ultrasonic signal collection distribution unit 8 fishing, whose input is connected to vkodom excitation generator 6, and an output - a preamplifier 7, the radius of curvature plane-kovognutyh electrode 2-4 is set based on the predetermined focal length F of the ultrasound beam antenna array for each electrode group with the same number

according to the formula of j p cf in in i

where, 2,3, ..., K is the number of the piezoceramic strip 1 in the antenna array.

The device works as follows.

In the radiation mode, in each channel of the device, an excitation pulse is generated, which from the output of the excitation generator 6 enters the distribution unit 8, a collection of ultrasonic signals, generating pulses delayed relative to each other by time. The pulses from the output of the block B of the distribution of ultrasonic signals are given to the corresponding flat-concave electrodes 2-4 of each piezoceramic strip 1, with the first pulse arriving at the far electrode relative to the working surface of the piezoceramic strip 1, i.e. on the flat-bent electrode 4, the next - on the electrodes, shifted respectively by

03424

&, 2 (and so on with respect to the far electrode towards the working surface of the piezoceramic strip 1, Piezo emitters formed by flat bent electrodes 2-4 and solid electroads 5 are wide-gap. The pulses of elastic oscillations excited by them propagate along acoustic waveguides, formed by the passive part of the piezoceramic strip 1, they are summed in phase, after which they are radiated without significant distortions into the working medium. Under these conditions it is longitudinal

j the resolution of the device practically depends only on the duration of the excitation pulse, which can be made sufficiently small.

0 In the reception mode, the ultrasonic waves incident on the grating aperture in each element excite pulses, the phase of which depends on the angle of incidence of the wave. These pulses propagate through acoustic waveguides and, when they pass through sections with flat bent electrodes 2-4, electrical signals appear on them. The last from each electrode come

Q into the distribution unit 8 of the ultrasound signal collection, where the signals from the flat-bent electrode 2 are delayed by 24t, and from the flat-bent electrode 3 - by the time ui and are in phase combined. From the output of the acquisition distribution unit 8, one total signal is fed to the preamplifier 7.

The invention allows to achieve

Q longitudinal resolution

(1.5-2) 71, where L is the wavelength of ultrasound in the working medium, while As in the known device, the longitudinal resolution is

j (5-6) D, which provides the effect of reducing the likelihood of making an incorrect diagnosis when it is used in medical diagnostics and rejection of suitable products when

Q its use in flaw detection.

Claims (1)

ULTRASONIC SCANNING DEVICE, containing a multi-channel radiation-reception scheme of ultrasonic signals, including in each channel an excitation generator, a preamplifier and a distribution unit for collecting ultrasonic signals, the input of which is connected to the output of the excitation generator, and the output to the preamplifier, and an antenna array of 2p + 1 electro-acoustic transducers, each element of which is made in the form of piezoceramic strips of different lengths with a solid electrode on one side, and t electrode applied on the other side in the form of strips whose radius of curvature Rj _n is determined by the relation where 0 · _η is the removal of the ith electrode from the surface of the η-strip, F; - focal length _e -i-ro · electrode and Y "- the ultrasonic velocity in peFF g zokeramicheskoy ^with the strip and the working environment, respectively, the electrodes 1 are respectively connected with the generators and the excitation channel preamplifiers circuits izlucheniyapriema ultrasonic signals of tlichayuscheesya in that In order to increase the longitudinal resolution, the ов electrodes are made flat-concave, while the concave side ΐ of the electrodes is directed toward the radiating surface g, and the average width. 1c electrodes satisfies the condition. ... · ΐ4 · ν. / Ϊ́ί | . where £ · is the working frequency of the piezo emitter formed by the ith. flat-concave electrode and a solid electrode. 1 1170342 2