GB1076571A - Improvements relating to colour television cameras - Google Patents

Abstract

1,076,571. Colour television camera. ELECTRIC & MUSICAL INDUSTRIES Ltd. Jan. 15, 1964 [Jan. 15, 1963; Feb. 23, 1963; Feb. 26, 1963], Nos. 1711/63, 7385/63 and 7566/63. Heading H4F. [Also in Division G2] A colour television camera employing a a plurality of pick-up tubes has an optical system arranged to share incident light among the tubes, the optical system including an objective lens and at least one fibre optic bundle so arranged that the objective forms an image on the front surface of the bundle and the bundle transfers the image to one of said pick-up tubes. Thus in Fig. 1, zoom lens 1 forms an image on the target of an image-orthicon luminance camera by way of reflectors 2 and 4, and also forms images on the front surfaces of fibre-optic bundles 15, 23 and 27 by way of beam splitting mirrors 6 and 7 and reflectors 14, 21 and 26. The bundles transfer the images to the target of vidicon colour camera tubes 8, 9 and 10, suitable component colour filters being provided on the front or rear surfaces of the bundles. The image formed by lens 1 is of size suitable for an image orthicon target and the taper in bundles 15, 25 and 27 is such as to reduce the transferred image to the size appropriate to a vidicon target. Reflector 2 is of a size to reflect a suitable proportion of the axial rays to tube 5, the marginal rays only forming the images for tubes 8, 9 and 10. Beam splitters 6 and 7 comprise glass discs with metallized front surfaces uniformly ruled to produce transparent strips between reflecting strips. The transmission to reflection ratios of mirrors 6 and 7 are arranged to be 2 : 1 and 1 : 1 respectively. The mirrors are disposed with the direction of the rulings at 45 degrees to the line scanning direction in tubes 8-10 and the mirrors are inclined so that the optical axes 11 and 20 are at a 45 degrees to the vertical plane through axis 12. The face plates of tubes 8-10 are formed of fibre-optic bundles. The face plates are contacted with bundles 15, 23 and 27 by an oil chosen to have a refraction index as close as possible to that of the bundles. A small orbiting motion relative to the pick-up tubes may be imparted to bundles 15, 23 and 27 as a gauged assembly and a similar motion is imparted to tube 5. A mirror similar to mirrors 6 and 7 may replace reflector 2. In modifications, Figs. 2-4 (not shown), the beamsplitting is effected by the fibre bundles which are merged at the input ends so that the corresponding fibres of each bundle are contiguous. The zoom lens forms an image on this common input surface either directly or by way of intermediate lenses.