Patent GB-1220705-A (GB)
Title: Optical image transmission, recording and reproduction systems
Inventor: FOURREAU PIERRE
IPC: G03B35/24
Filed: 1968-07-08
Abstract: 1,220,705. Colour television. P. FOURREAU. 8 July, 1968 [7 July, 1967], No. 32557/68. Heading H4F. [Also in Divisions G2 and H1] In an optical projection system for picking up and reproducing images in colour and in depth in a television system or a corresponding cinematographic system, a series of vertical lenticular elements in juxtaposition are arranged in conjunction with a series of horizontal colour filters. As shown in Fig. 2, a television pick-up tube comprises a conventional single-gun camera 1 with objective lens system 4 and photocathode 3, and two screen sections 6 and (7) interposed between subject 5 and lens system 4 and rigidly attached to camera 1 by a case 9. Screen section 6 comprises a series of plano-concave elements 6<SP>1</SP>-6<SP>n</SP> of transparent plastic or glass on the plane surface of which is fixed screen section (7), (Fig. 3, not shown), which comprises transparent colour filters in the form of juxtaposed strips of alternating colours red, blue and green in a direction at right angles to the axis of elements 6<SP>1</SP> to 6<SP>n</SP>. Fig. 4 (not shown) illustrates an alternative form of screen section 6 in which two series of plano-concave elements are placed against one another with the concave faces towards one another. To prevent distortion of the image in planes behind the plane on which the device is focused a cylindrical plano-convex lens may be employed on the front surface of the screen section of Fig. 4. A further lens employed on the rear surface of section 6 causes convergence of the rays from this section to the objective 4 (Fig. 5, not shown). Screen section (7) is disposed between this latter lens and section 6. Fig. 2 shows the ray paths for subjects 51, 511 and 5<SP>111</SP> at different distances away from the camera. A laterally compressed, non- reversed image 10, different for each position, is produced on the focal image plane P. Fig. 8 shows a corresponding colour television display tube comprising a conventional single gun tube with a screen portion similar to the screen sections of the pick-up tube, said screen portion comprising vertical plano-convex cylindrical lens elements 18<SP>1</SP> to 18<SP>n</SP> fixed to a rectangular transparent plate (15) (Fig. 10, not shown) on the other side of which is deposited the colour section (19) formed of a series of trichromatic phosphors arranged in the form of horizontal strips of alternating colours. Fig. 8 shows the ray paths for rays travelling to the eyes LE, RE. Three-gun cameras or picture tubes may also be employed in which case one line in three is scanned by each gun, producing sequential transmission of lines. In the corresponding cinematographic system the optical system of the film camera is as described above for the television camera and a positive transparency is produced by a black and white reversal film, the colour reproduction being effected by projecting the film on to a translucent screen whose projector-side surface comprises alternating red, blue and green horizontal filter strips and whose viewing-side comprises vertical convergent piano-cylindrical lens elements. In a telefilm system the film record produced as above is scanned by a flying spot cathode-ray tube and then displayed on the colour display tube described above; in this case the film record may be a negative transparency, the image reversal being produced electronically. A colour film may be reproduced in depth by projecting it on to the screen section 6 and 7 of the television camera described above with reference to Fig. 2.