GB1034889A - Image-orthicon television pickup tube - Google Patents

Abstract

1,034,889. Television pick-up tubes. ROBERT BOSCH G.m.b.H. Dec. 20, 1963 [Dec. 20, 1962], No. 50420/63. Heading H1D. In an image orthicon television pick-up tube comprising a field mesh electrode adjacent the target, and an apertured gun anode 4 which acts as collector electrode for the return beam and as first dynode of a multiplier system 5, an electrostatic field, effective in a direction perpendicular to both the gun axis and the direction of line scanning, is superimposed upon the electron beam focusing system, to ensure that the aperture in the gun anode lies outside the scanning pattern traced upon the anode by the return beam and at a distance not exceeding 0À5 mm., and preferably less than 0À2 mm., from the edge of this pattern. The pick-up tube may comprise an electrode 6 which guides secondary electrons from anode 4 into multiplier 5, a screen electrode 7 connected to final anode 9, and a suppressor electrode 8 which prevents secondary electrons released from the field mesh electrode from entering the gun system. As shown, electrode 8 is at cathode potential and has an edge slanted at 4 to 8 degrees, e.g. 5 degrees, to produce the required electrostatic field. Alternatively, this field may be produced by an auxiliary electrode, e.g. an evaporator used in forming the target, extending around part of the circumference of an axially-symmetrical suppressor electrode 8 and connected to electrode 6.