GB811293A - Improvements relating to telecine apparatus - Google Patents

Abstract

811,293. Television. ELECTRIC & MUSICAL INDUSTRIES Ltd. July 22, 1955 [July 22, 1954], No. 21369/54. Class 40 (3). Interlaced scanning of a continuously moving kinematograph film 4 is effected by an interlaced raster at 3 having alternate fields inverted with respect to intervening fields, a first image of the raster being formed on the film by way of a projection lens 6 and a second image being formed by way of the same projection lens and a plane reflector 7 which serves to displace and invert the image. In operation, the same area of the film is scanned in successive television fields, the relative inversion in the optical paths resulting in identical directions of scan so that correct interlacing' is obtained. A shutter 9 obturates alternate images at field rate, the shutter being placed behind the film before a condenser 8 and photo-cell where a film is being scanned to generate signals, and being placed before the film for recording. The film is advanced during each television field period by half the standard distance between film frames. and raster 3 is arranged to be of half normal height. Alternate fields in the raster are inverted by employing a symmetrical sawtooth wave of half field frequency for field deflection in place of the normal scanning wave. Intensity differences between successive fields arising from the use of reflector 7 in one optical path may be compensated by controlling the raster intensity. Adjustment of interlace may be effected by control of vertical shift. For scanning a film to generate or record signals as described above, raster 3 is produced on the screen of a cathode-ray image-reproducing tube 2. To generate signals with a cathode-ray pick-up tube, raster 3 is scanned on the target of the tube and the film is illuminated by a light source mounted in place of the photo-cell. Specification 475,032, [Group XL], is referred to.