GB1240468A - Improvements relating to television cameras - Google Patents

Abstract

1,240,468. Television. E.M.I. Ltd. 28 Oct., 1968 [8 Aug., 1967], No. 36313/67. Heading H4F. The response lag at low levels of illumination of a television camera comprising one or more pick-up tubes having photo-conductive targets is reduced by additionally illuminating the target(s) uniformly by biasing light from a source 4 transmitted through an optical fibre 3 whose emergence end is located on or near the axis of the objective 1, which may be a zoom lens. Fibre 3 is positioned such that light from source 4 travels either directly to the target electrode or, as shown, via a beam splitting device 2 which splits the beam from objective 1 into red, green, blue and luminance components for colour reproduction. In an alternative embodiment (Fig. 2, not shown), two optical fibres, both terminating outside the optical path from the subject are employed, the fibre ends being directed such that light from source 4 again illuminates the required area. The or each optical fibre may be terminated by a small reflector.