GB459291A - Improvements in electrical arrangement for controlling incandescent lamp screens adapted to reproduce pictures - Google Patents

Abstract

459,291. Electric reproduction of kinema films. REKLAMAKTIEBOLAGET EPOK, 14, Drottninggatan, Stockholm. June 6, 1935, No. 16449. Convention date, June 6, 1934. [Class 118 (ii)] [See also Group XL] Relates to an electrical arrangement for controlling incandescent lamp screens adapted to reproduce pictures by means of gas discharge tubes, using successive transmission of part pictures and employing alternating or pulsating current for feeding the lamps and controlling the tubes. According to the invention, a plurality of double-anode grid-controlled gas discharge tubes are employed, each of which has co-ordinated with it two photoelectric cells, the cells being connected in groups, each adapted to control a group of lamps, the arrangement being such that each group of photo-cells has a positive voltage applied at the same time as the corresponding group of lamps. The source of voltage for the cells may be the centre-tapped secondary winding of a transformer or a switching device for feeding a direct current intermittently. As shown, one pair of cells 1, 1<a> is associated with the double-anode grid-controlled gas discharge tube 8, whilst another pair of cells 2, 2a is associated with the other tube 9. The cells are connected as shown to the centre-tapped secondary of a transformer 3 which is connected to the same source of A.C. supply as the transformer 13, the centre-tapped secondary of which is connected as shown with the lamps 11, 11<a> and 12, 12<a> connected to the anodes 5, 5<a> of the tubes 8, 9 respectively. With this arrangement, the cells 1, 2 have a positive voltage applied thereto and the lamps 11, 12 are lit up during one half-wave and the cells 1<a>, 2<a> have a similar voltage applied thereto, and the lamps 11<a>, 12<a> are lit up during the other half-wave. Instead of feeding the groups of cells through the transformer 3, they may be fed through an inductance and capacity respectively. Specification 432,501, [Group XL], is referred to.