GB1041590A - Improvements in or relating to colour television cameras - Google Patents

Abstract

1,041,590. Television. MARCONI CO. Ltd. Nov. 1, 1963 [Nov. 30, 1962], No. 45384/62. Heading H4F. A colour television camera comprises two image orthicon tubes 1, 2, means for projecting an image of a subject of transmission, e.g. the arrow in Fig. 1, on to tube 1, optical means including red colour filter 9, blue colour filter 11, dichroic or half-reflecting mirrors 4, 6 and ordinary mirror 7 for projecting red and blue images side by side on to tube 2, means for causing the scanning ray in tube 1 to scan the image projected thereon in lines extending thereacross, means for causing the scanning ray in tube 2 to scan across the two images projected thereon in lines extending across both images and any space therebetween and starting and finishing simultaneously with the starting and finishing of two lines in tube 1, and means for taking off luminance signals from tube 1 and chrominance signals from tube 2. The colour filters may be incorporated in the mirrors 6 and 7 or in the optical systems 8 and 10. The image on the luminance tube 1 contains all colours but colour trimming filters may be provided. Scanning in tube 1 is effected in accordance with television standards (Fig. 3, not shown) and scanning in the chrominance tube 2 is at a line frequency which is half that employed in the luminance tube 1 (Fig. 4, not shown). The spacing between the coloured images on tube 2 (Fig. 2, not shown) is typically about <SP>1</SP>/ 5 of the width of each coloured image in the direction of line excursion but by adopting a wave with a portion of reduced slope in the middle of the flank for scanning in tube 2 (Fig. 5, not shown) smaller values of spacing may be used. Tube 2 produces a red chrominance signal line during each alternate line in the luminance tube 1 and a blue chrominance signal line during each of the other alternate lines in tube 1. In the N.T.S.C. system both colour chrominance signals are required in each luminance line and therefore the output from tube 2 is fed to two chrominance signal channels one for the red and the other for the blue signals via branched paths and a double-pole change-over switch, one of the branched paths containing a delay line giving a delay equal to one line period of tube 1, the other paths being underlayed (Fig. 6, not shown).