GB703915A - Improvements in and relating to the recording of television pictures upon cinematograph film - Google Patents

Abstract

703,915. Kinematograph apparatus. BRITISH BROADCASTING CORPORATION. Dec. 21, 1951 [Sept. 21, 1950]. No. 23216/50. Class 97(1) Apparatus for recording television pictures on intermittently moving film comprises optical means capable of producing on the film simultaneously two mutually displaced images of a television screen. shutter means in the image forming light beams arranged so that, during a cycle period substantially equal to the period of two successive television scans, each of the beams is uncovered for a period substantially equal to one television picture period and both are obscured during a period when the film is advanced two frame heights. Figs. 4 and 5 show elevations at the two sides of one embodiment. The casing 10 includes compartments 14, 15 separated by a longitudinal wall 12, both being separated, by a transverse wall 11, from a compartment 13. The shaft 17, Fig. 4, of a driving motor 16 is coupled to a shaft 19 which carries the constant-diameter cam 21 of the intermittent-feed mechanism. The shaft 19 drives, through gearing 18, 22 a shaft 23 which drives through gearing 24, 25 a drum cam 26 on a sleeve 27 concentric with the spindle 19. The gear 25 meshes with a gear 59 on a shaft 58. The shafts 23, 58 carry spiral gears 57 meshing with others 5b on the spindles 55 of sprocket 54, Fig. 5, round which the film 36 passes. The film also passes round a sound drum 64 on a spindle 65 also carrying a flywheel 67, Fig. 4. The spindle 27 also carries a pinion 77 which drives through an idler 76, a pinion on a shaft 75 carrying a bevel pinion 74 driving pinions 71, 73 which drive'the shutter drums 68, 69 whose peripheral flanges are shown developed in Fig. 10. Each has a slit 78, one frame height in width and registering with the upper half of the double frame exposure aperture 43, and a similar slit 79 similarly registering with the lower half. The slits overlap ovef half their length. The whole length of each is half the circumference of the drum. The film between the gate members 33 and 34 is reciprocated in a direction perpendicular to the film by a linkage (not shown), actuated by the cam 26, in and out of engagement with the feed claw, of which only alternate strokes are used. Light from a television screen image is reflected by an inclined mirror (not shown) carried by a frame 87, Fig. 5, on to a semi-reflecting mirror 81 and a mirror 82 slightly inclined to it and adjustable by a screw 86. From the two light beams so formed the lens 83 forms two images on adjacent film frames. The images may be inspected by a viewing device accommodated in the slot 53 in the partition 12. Each film frame is exposed for a complete television scan period i.e., with interlaced scanning, two frame scans. In the described embodiment, when used with interlaced scanning, the exposure periods determined by the shutter openings 78, 79, overlap by one frame scan period and together occupy three scan periods, the duration of a fourth being used for film feed. An exposure period need not begin at the commencement of a frame scan, i.e. the exposure may cover one whole scan and two parts respectively preceding and following it. Similarly, with -non-interlaced scanning, each exposure period again equals a complete television scan period (i.e. a single frame scan in this case) and one at least of the overlapping exposures is made up of parts of two separate (in this case successive frame) scans. The recording apparatus need not be exactly synchronized with the television picture but may be so synchronized by amplifying television frame synchronizing pulses to form a supply for the motor 16.