GB1048409A - Tuning indicator tubes - Google Patents

Abstract

1,048,409. Tuning indicators. INTERNATIONAL STANDARD ELECTRIC CORPORATION. Sept. 22, 1965 [Sept. 22, 1964], No. 40323/65. Heading H1D. In a voltage-indicator tube for a stereophonic receiver, electrons projected from the cathode 3 towards the screen 2 are divided into three beams by the electrodes 13, 14, the two outer beams being subject to the control of plate electrodes 9 and 10, and the centre beam to the control of rod electrodes 11, 11a, to which a signal dependent upon the presence and intensity of a stereophonic component in the received signal is applied, the electrode geometry being such that only when the latter component is of sufficient strength to ensure satisfactory stereophonic reception is the centre beam permitted to strike the screen. Cathode 3 is surrounded by a grid 4 which is supported by three struts 4a which act as shields, and enclose control electrodes 5 and 6, to which voltages representative of the difference and sum, respectively, of the left and right stereophonic channels are applied, whereby amplified signals are produced on anodes 7 and 8, which are connected, respectively, to deflection electrodes 11, 11a and 9, 10. Electrode 12 is connected to a conductive tin oxide layer included in the screen, portions 18 and 19 preventing the impingement of secondary electrons upon the screen, and the angled inner edges 20, 21 improving the deflection sensitivity of electrodes 9, 10. A colour filter may be provided for the central beam. In an alternative embodiment (Fig. 5, not shown) electrodes 9 and 10 are of rod form, and electrodes 11, 11a are plates mounted parallel to electrodes 13, 14.