GB380109A - Improvements in or relating to controlled light sources for use in electro-optical transmission systems - Google Patents

Abstract

380,109. Television; arc lamps. BANKS, G. B. and BAIRD TELEVISION, Ltd., 133, Long Acre, London. June 2, 1931, No. 16094. [Classes 39 (i) and 40 (iii).] One or both of the electrodes of a modulated arc employed for television are so constructed as to withdraw heat from the electrode so as to reduce its luminosity. A suitable electrode for this purpose consists of a copper tube packed with cerium oxide or a material containing a large proportion of cerium oxide. The packing is dried before placing in the tube, which may be thickened at the top end as shown in Fig. 4. Fig. 5 shows an anode 50 hollow to allow the circulation of cooling water therethrough. The arc is viewed through an opening 52 in the anode which assists in masking the light in the required manner. The light employed should be that proceeding from the flame within a predetermined cone, as described in Specification 380,234. The circuit employed is shown in Fig. 1. The image signals after amplification are passed to a large power valve 4 in the anode circuit of which is a transformer 6. In the secondary circuit of this transformer are the are 3 and a condenser 12 and resistance 14 in parallel. Direct current is supplied to the arc from a source 8 through an adjustable resistance 10. Specification 269,219, [Class 39 (i), Electric lamps, Arc &c.], also is referred to.