GB536290A - Improvements in or relating to television receivers - Google Patents

Abstract

536,290. Television. SCOPHONY Ltd., and OKOLICSANYI, F. Aug. 3, 1939, No. 22531. [Class 40 (iii)] [Also in Group XX] Relates to optical systems, particularly for receivers using supersonic-wave light-modulating' devices, in which the definition may be increased without a proportional decrease in the light. The system comprises optical focusing means, e.g. lens 18, having power in the line scanning direction (i.e. the plane of Fig. 3) for forming an image of an aperture, a divided focusing member comprising elements, e.g. lenses 19a, 19b, having power in the image scanning direction (i.e. the plane of Fig. 2) for forming, e.g. on screen 24, coincident images of portions of the aperture 9, and a field lens element 16a, 16b projecting the light from each portion on to the corresponding divided lens 19a, 19b. In this way the size of the image of the aperture is reduced in one direction without an increase in the angle of the light cone which would result if simple focusing systems were used. The lenses 18 may form images in their respective directions on a common focusing plane 24, or in different focusing planes in which case a further optical system is used to re-focus at least one of the images to form a final image in both directions in the same focusing plane. The lenses 18 may be close together as shown or separated. The elements 16a, 16b of the field lens may be parts of spherical lenses or have different power in the two directions. The invention is described as applied to (1) a receiver using Kerr cells, Figs. 5, 6 (not shown), (2) a receiver using supersonic wave modulators in which one side of the supersonic cell is provided with lens elements 16a, 16b, Figs. 7 and 8 (not shown), the images in the two planes being formed at different distances from the cell, in one plane on the final screen and in the other plane on the high-speed scanner, from which an additional lens focuses it on the screen, and (3) a receiver using a supersonic cell in which an additional projecting system as in Specification 536,289 is used, Figs. 9, 10 (not shown).