Patent GB-476865-A (GB)
Title: Method of and cathode ray tube apparatus for transforming luminous energy into electrical wave energy
IPC: H01J31/28
Filed: 1936-05-11
Abstract: 476,865. Cathode-ray tubes. ZEITLINE, V., ZEITLINE, A., and KLIATCHKO, V. May 11, 1936, No. 13331. Convention date, May 9, 1935. [Classes 39 (i) and 40 (iii)] Light is directed on to a photo-electric or fluorescent screen, the insulated particles of which become charged and the charged particles are scanned by the cathode beam so as to produce fluctuations in the electric field near the screen which produce corresponding changes in the current in one or more collecting electrodes mounted outside the tube ; the current in the external electrode is amplified for television transmission. As shown in Fig. 1, the tube contains a granulated photo-electric screen 6, an earthed anode 4, a modulating grid 3 and a deflecting system 5. The image projected on the screen produces electrons passing to the anode, leaving the screen particles positively charged. Neutralization of the positive charges by the scanning beam sets up disturbances in the electric field which are reproduced in the external electrode 10 and amplified at 11. The electrode 10 may consist of a straight wire, a helix or spiral, a metal box or spherical casing enclosing the tube, Figs. 2 and 4 (not shown), or a transparent vessel containing electrolytic liquid, Fig. 3 (not shown). For transmitting coloured images, three light filters are interposed between the tube and a transparent electrode containing liquid, Fig. 5 (not shown). In the arrangement shown in Fig. 7, the photo-electric current is added to the variations in current in the external electrode. The screen 6 is connected through a resistance 11a to the amplifier 11, and the electrode 10 is connected to earth either directly or through a battery 6b. An additional internal electrode 6a serves to regulate the charge produced by the accumulation of luminous energy. In a modification of this arrangement the electrode 6a is connected and the currents to the anode 4 and in the electrode 10 are superposed, Fig. 8 (not shown). In an arrangement for the transmission of films, Fig. 7 (not shown), a light source illuminates a slot over which the film is moved, and the image of the slot is projected through a transparent liquid electrode on to the screen, the image in the transverse direction to the slot being diffused. A photo-electric surface may be formed by developing and fixing a photograph of a mosaic on a plate of glass or mica. The silvered mosaic surface is covered by a photoelectric metal, and the layer is vaporized until an amalgam remains on the silvered part. In another method, the surface of the glass screen is made coarse by sand-blasting before distillation of the photo-electric metal. A screen having photo-electric and fluorescent materials is made by coating the glass with a mixture of fluorescent materials with barium and sodium nitride. After gentle heating the photo-electric particles remain insulated by particles of fluorescent materials. The Specification as open to inspection under Sect. 91 comprises also a tube having an internal collecting electrode, and a screen consisting of a metal sheet impregnated with fluorescent material. This subject-matter does not appear in the Specification as accepted.