GB1276161A - Recording and reproducing colour television signals - Google Patents

Abstract

1276161 Colour television ELECTRONIC RESEARCH CORP 3 June 1969 28117/69 Heading H4F [Also in Division G5] Relates to a magnetic recording system in which colour sequential video signals are recorded in parallel tracks on a magnetic tape and in which each adjacent pair of tracks is played back simultaneously. In a first embodiment, Fig. 5, the scanning disc 2 has a pair of additional heads 60 and 70 vertically spaced by one track width w from the conventional heads 6 and 7. In the record mode field sequential colour information is recorded using heads 6 and 7 (or heads 60 and 70), a red even field being recorded in a first track by head 6, a blue odd field by head 7, a green even field by head 6, a red odd field by head 7, a blue even field by head 6, a green odd field by head 7, &c. In playback the complete signal train from heads 6 and 7 is passed through one preamplifier and demodulator and the same signal train but delayed by one field from heads 60 and 70 is passed through another preamplifier and demodulator (Fig. 7, not shown), the resulting demodulated signal being gated into three channels for the red, green and blue signals with a normal and a delayed field signal being present in two out of every three field periods. In a second embodiment the head configuration is as shown in Figs. 8 and 9 with the normal head 6 and head 9 spaced 180 degrees from head 70 and head 80, and # degrees from head 80 and head 70 respectively, and head 80 and head 70 stacked {w-(#/180 degrees)w} above head 6 and head 9 respectively. With the signals being recorded by heads 6 and 9 in parallel the vertical interval periods 14a, 14b, 14c &c. are alternately staggered as shown in Fig. 10 and the first interval period 12b 2 , 12d 2 &c. recorded by head 9 comprises the same information e.g. sync. pulses, as that recorded at the end of tracks 12a, 12c &c. During playback head 80 for example will scan this information when tape contact with head 9 is lost, so that no difference is detected between the actual vertical interval and that which would be present in the preferred configuration of Fig. 5. With this arrangement switching between the heads which takes place during the vertical pulse period does not effect the actual picture content. Reference is made to recording line sequential colour video signals. Half as many heads may be employed with the tape traversing 360 degrees instead of 180 degrees of the scanning assembly.