Patent GB-1173481-A (GB)
Title: Improvements in and relating to ultrasonic inspection apparatus and methods.
Inventor: MEYER EDWARD PAGE
IPC: G01N29/265
Filed: 1967-03-14
Abstract: 1,173,481. Ultrasonic inspection; cathoderay tube operating circuits. PICKER ELECTRONICS Inc. 14 March, 1967, No. 11795/67. Headings H4D and H4T. The invention relates to ultrasonic inspection apparatus comprising an electroacoustic transducer directing a beam of ultrasonic energy at a test object and carried by an arm made up of at least three pivotally connected sections connected to respective position transducer means, the signals from which are utilized to control the position on a visual read-out device of a display which is produced by the signal output of the electroacoustic transducer due to the reception of ultrasonic energy reflected by the test object. The invention also relates to a method of ultrasonic inspection in which a beam of ultrasonic energy is directed, successively, at different points on the surface of a test object and at each point, swept through an angle, the echo signals due to reflection by the test object of the ultrasonic energy being utilized to produce a display the position of which is controlled in accordance with the position of the beam relative to the test object. Fig. 1 shows the construction in which the electroacoustic transducer 32 is carried by a first arm 40 pivotally connected to a second arm 36 pivotally connected to a third arm 34 the latter being pivotally connected to parallel members 28 (also Fig. 2, not shown) secured to a frame 10 adjustably mounted on a support 12, 14 by means 16, 17. Each arm is attached to a respective pulley 60, 54, 52 (see also Fig. 7) which rotates about the respective pivots 43, 39, 37 as the associated arms are rotated and this motion is transmitted via belt means, e.g. steel wire (the pivots 39 and 37 also carrying freely mounted additional pulleys) to pulleys 47, 62, 49 secured to sine-cosine potentiometers 22, 24, 26 (Fig. 4), carried by the frame 10. The outputs of potentiometers 22 and 26 indicative, respectively, of motion of arms 34 and 36 are combined in Y and X adders as shown in Fig. 9 to provide signals determining the position of the origin of a raster scan which is produced on a display tube 74 by sweep generators 80, 82. The latter generate sawtooth waveforms the time rate of rise of which is determined by the sine-cosine outputs from potentiometer 24 in accordance with the angular position of the arm 40 (i.e. in accordance with the angular position of the ultrasonic beam from transducer 32 relative to the horizontal). The scan is initiated by trigger pulses from a clock 84 which controls the pulses 88 driving transducer 32 via a delay device 86 which compensates for the time of travel of acoustic wave over a distance equal to that between the radiating face of transducer 32 and pivot 43 so that the sweep will have advanced an equivalent distance before energization of the transducer. In operation the transducer is positioned against the test object, which may compris eportions of the human body, and at each position it is oscillated through an angle as indicated in Fig. 10B, received echo signals being utilized via amplifier 90 to bright-up the beam of the display tube which is also brightened by the transmitted pulses so that the distance of the reflecting (impedance discontinuity) surface from the outside of the body is indicated. The size of the display may be varied by variation of the voltage supplied to potentiometer 24 (e.g. by rheostat 94 or by varying the gains of amplifiers 72, 78.