GB1079802A - A magnetic-tape device for recording and playing back television signals - Google Patents

Abstract

1,079,802. Recording and playback of television signals. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. Sept. 2, 1964 [Sept. 18, 1963], No. 35909/64. Heading G5R. The length of tape required for recording television signals is reduced by recording every nth field or frame and, on playback, repeating every field or frame n times. Recording.-The tape 1, Fig. 1, passes over at least 300 degrees of a contra-rotating drum 3 provided with a recording head 4 which moves at twice the linear speed of the tape. Recording of a picture starts with the head in the position shown and is completed when the head has rotated 120 degrees to the position shown in dotted lines. The head is muted for the next two pictures, by which time it will have returned to the initial position and the tape will have moved so that the head is at the end of the previously recorded portion. Thus one picture in three is recorded and the picture information is recorded in succession without any gaps on the tape. Head switching is effected in response to the picture synchronizing pulses and to a switch comprising a fixed contact plate 7 and a moving contact 6 mounted on the drum, Figs. 2 and 3 (not shown). The picture and sound may be recorded on separate tracks on half the width of a tape, the other half of the tape being used subsequently when the tape is turned over. Playback.-The picture signals are picked up by head 16, Fig. 4, whilst moving from position 27 to position 28; the head 15 then picks up the same picture whilst moving from position 29 to position 31, and the picture is picked up a third time by head 16 in moving from position 32 back to its initial position 27. As in recording the tape moves at half the speed of the heads and the head switching is controlled by the synchronizing signals and by the switches formed by a fixed contact 19 and contacts 17 and 18 which rotate with the heads, Figs. 5 and 6 (not shown). Recording playback apparatus.-The tape is driven by a drum 44, Fig. 8, which is driven at half the speed and in the opposite direction to the head drum 40 which is provided with two heads so that it may be used for either recording or for playback, one of the heads being inoperative whilst recording. The drums are driven by respective synchronous motors 45 and 46, and the head drum may be provided with an extension 49 carrying connections 50 for the heads and also carrying the contacts 17 and 18 of Fig. 4. An erase head may be provided in the tape path between the supply spool 34 and the drum 40, and a sound record/ playback head may be provided between the drum 40 and the take-up spool 37, Fig. 7 (not shown).