Patent GB-1191692-A (GB)
Title: Improvements in or relating to Colour Video Recording
IPC: H04N5/915
Filed: 1967-05-15
Abstract: 1,191,692. Colour video recording or reproducing. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 15 May, 1967 [18 May, 1966], No. 22334/67. Heading G5R. A method of recording and reproducing colour video signals on and from a record carrier in tracks each containing at least one kind of information about at leat one field period of a video signal is characterized in that of all the kn<SP>2</SP> kinds of field information of kn successive fields, wherein k is a positive integer and n is the number of kinds of information of a colour video signal, kn kinds of field information are recorded in n tracks, the n kinds of information each having a length of at least one field period and always being recorded in the same sequence in these n tracks on the record carrier; during reproduction n reproducing members simultaneously scan the tracks in such manner that each track is scanned n times; the n reproducing members each scan simultaneously a different kind of information of the colour video signal and each scans successively all the kinds of information in cyclic sequence. As shown in Figs. 1 and 2, a recorder tape 1 is helically laid around a drum 2 having a slot 4 provided at right angles to its axis 3 and in which a group 5 of three recording and reproducing members 6, 7 and 8 (relatively spaced by a distance a cosec α in the direction of length of the recorder tape) can rotate. α is the angle made by the tracks 9 with the longitudinal direction of the tape 1 and a is the distance between the centres of the tracks 9, that is, the distance moved by the tape 1 in the direction of the axis 3 after one revolution of the recording and reproducing members 6, 7 and 8. Fig. 2 shows the tracks when k = 1. The group 5 records three tracks, each containing one of the three kinds of information of a colour video signal, e.g. R,G and B associated with the odd field F 1 . During the next two revolutions the recording members 6, 7 and 8 are not energized, but during the fourth revolution they record the even field F<SP>1</SP> 2 , the tape having moved on a distance 3a during the preceding revolutions. During the scanning process the reproducing members 6, 7 and 8 are continuously switched on and scan successively the tracks: R, G and B of F 1 ; G and B of F 1  and R of F<SP>1</SP> 2 ; B of F 1  and R and G of F<SP>1</SP> 2 ; R, G and B of F<SP>1</SP> 2 ; and so on. Thus, during two of the three revolutions, the reproducing members 6, 7 and 8 scan two kinds of information of an even field and one kind of information of an odd field, or vice versa, so that special steps are necessary (e.g. a delay line) to turn kinds of information of even fields into kinds of information of odd fields, or vice versa. But this difficulty may be overcome by making k even, e.g. 2. In Fig. 4 recorder tape 21 is helically laid in a half turn around a drum 21 and is swept by each of two recording members 26 and 26<SP>1</SP> through an angle of 180 degrees; the tape moves on over a distance a after half a revolution of the recording members. Where k = 1 and n = 3, tracks as shown in Fig. 6 are produced, the recording members being continuously switched on. During scanning, two groups 25 and 25<SP>1</SP>, Fig. 6, each of three reproducing members 26 to 28 or 26<SP>1</SP> to 28<SP>1</SP>, simultaneously scan three tracks, e.g. R of F 1 , G of F<SP>1</SP> 1  and B of F 2 ; G of F<SP>1</SP> 1 , B of F 2  and R of F<SP>1</SP> 2 ; and so on.