GB486915A - Television receiving tube - Google Patents

Abstract

486,915. Cathode-ray tubes. RADIOAKT.-GES. D. S. LOEWE. Oct. 8, 1936, No. 11336/38. Convention date, Oct. 16, 1935. Divided out of 486,657. [Class 39 (i)] In a television receiving tube the moving cathode-ray is intensified by directing it onto an intercepting plate 19 heated by separate means to increase the secondary emission which, by electron-optical means, is projected onto the luminous screen 23. In the form shown the cathode-ray from cathode 1, controlled in intensity by modulating electrode 27 is focused by the lens 2, 4, 5 in a plane 19<1> and is deflected over that plane by plates 29, 30. A homogeneous magnetic field. 20 deflects the cathode-ray through a right-angle onto the plate 19, which has the same potential as anode 5. This plate is coated with barium or other emissive oxide and is heated directly or indirectly by Joule heat, by electronic bombardment or by induction, to a temperature at which its thermionic emission is small relatively to its secondary emission. The amplified ray is accelerated by the plate 25 and is deflected by the field 20 so as to be focused on the screen 23 by the coil 24. The magnetic field 20 may be replaced by two electrostatic fields separating the primary and secondary beams.