GB650689A - Improvements in or relating to cathode ray tubes - Google Patents

Abstract

650,689. Cathode-ray tubes. RADIO CORPORATION OF AMERICA. April 10, 1947, No. 9606. Convention date, April 12, 1946. [Class 39 (i)] A cathode-ray storage tube comprises within the envelope an electron gun, a conductive target having a plurality of mutually insulated elemental areas, an electron multiplier between gun and target, electrostatic scanning means and an electron-permeable screen adjacent and in front of the target which controls secondary electrons bombarded from the target to which successive signal potentials are applied. The grid 4 and first and second anodes 5, 9 are of tubular construction mounted together by means of four mica strips 11 and through which the electrodes are welded to metal strips 13, 14, 15. To the end of the second anode is welded a metal disc 17 separated by mica discs and spacing rods from a further metal disc 20 sandwiched between mica discs 21, 22. Holes in these discs accommodate and insulate metal rods 37, 38 which are attached to and support the horizontal and vertical deflecting plates. A shield disc 16 surrounds the gun assembly and is flanged at 45a and welded to a cup-shaped gun mount 45b. A focusing electrode 47 is positioned at the gun end of the wall coating 46 and multiplier stages 48-53 and collector 54 are positioned over the shield tube 16 accommodating the gun electrodes. The target 2 is convex and of aluminium with an oxidized coating and a screen 61 stretched over the surface. A focusing ring 62 is adjacent the target. In the operation of the tube, the high velocity beam from the electron gun liberates secondary electrons from the target surface which tends to assume the potential of the screen 61. In a coherent pulse radar system echoes from stationary and moving objects are received on the signal plate and control the secondary emission therefrom, but only the echoes from the moving objects vary sufficiently in amplitude and change in phase to produce modulation of the electron beam returning to the multiplier. In order to compensate for the slow variation of amplitude in successive pulses from a fixed object due to material breadth of radar antenna, two tubes may be run in cascade. Specification 634,639 is referred to.