Patent GB-1472130-A (GB)
Title: Ultrasonic wave transmitting and receiving apparatus
IPC: G10K11/34
Filed: 1974-05-15
Abstract: 1472130 Ultrasonic inspection apparatus TOYKO SHIBAURA ELECTRIC CO Ltd 15 May 1974 [21 May 1973] 21515/74 Heading G1G The Specification describes an ultrasonic transmitting and receiving apparatus which effects high-speed scanning of a focused ultrasonic beam from a linear array of transducers which are selectively electronically connected so that a group thereof are focused on a point, e.g. in a test specimen, which point is made to scan the specimen by selectively switching the transducers; the switching process continuously displaces the group of switched-on transducers along the array. The transmitting circuit, 50, 51, Fig. 2, comprises a control pulse generating unit, which consists of Fig. 3 (not shown) a clock, (501), a counter, (503), and a shift register, (502), interconnected to produce control pulse signals C1-C6, Fig. 4, which are fed into a delay pulse generator unit 51. Unit 51, Fig. 3 (not shown) comprises three delay circuits which produce delayed signals 170, 171, 172, Fig. 4. The delay times D0, D1, D2 are determined, Fig. 5, by the propagation times between each of the six operative transducers and the required point of X. As the transducers 1 and 6 have the longest propagation time, the delay time D0 is taken to be zero. By means of logic circuitry, Fig. 3 (not shown) signals dl to d6 are derived from control signals C1-C6 and delayed signals 170, 171, 172, and are illustrated in Fig. 4, lines 101-106 respectively. Signals d1 to d6 energize respectively drive pulse energizing units P1 to P6 to produce outputs p1 to p6. Outputs p1 to p6 are selectively applied to the transducers 53 by electronic switching unit 52. Switches 51-56 are exclusively closed to energize transducers 1-6 so that focus point X1 is irradiated. Energizing units P1-P6 are interconnected with switches S1 to Sn so that irradiation of point X2 takes place by exclusive closure of switches S2-S7. Unit P1 is now connected to transducer S7. The scanning process proceeds as each successive group of six transducers is selected by switch unit 52 which is driven by scan pulses SC1 to SCn. Each switch Sn comprises a circuit of Fig. 7. The scan pulse generator SC (see Figs. 8A, 8B, (not shown) provides scan pulses SCn through e.g. inverter G11 to the base of transistor TS 1 , which turns on and allows a drive pulse from unit P1 to pass to the secondary winding of pulse transformer T 1 , transistor Tr 1  being held off by the signal from inverter G21. Transducer 1 is thereby energized by signal P1, and the received echo pulses pass to receiver Q1. The receiver, Fig. 9, includes amplifiers A1-A6, switches R1-R6, delay circuits 271, 272, 273 and CRT display 300. The received echo signals from the respective six energized transducers pass through respective amplifiers A1-A6 to respective switch units R1-R6 each comprising means to switch the received signals to one of delay circuits 271, 272, 273 having delays D0, Dl, D2 respectively. The switch units R are controlled by digital circuitry, Figs. 10, 11A, 11B, (not shown) so that each echo signal is connected to a delay circuit 271, 272, 273 whose respective delay coincides with the delay impressed in the corresponding transmitted signal. The delay circuit outputs are combined, amplified at 300 and displayed e.g. on a CRT display as the image signal.