GB1340077A - Pick-up tubes - Google Patents

Abstract

1340077 Image pick-up tubes EMI Ltd 15 Jan 1971 [28 Jan 1970] 4036/70 Heading H1D A pick-up tube (e.g. TV camera) includes a mesh electrode with a skirt portion 28 interposed between a wall anode 27 and the target 29 such that the facing ends of the wall anode and of the skirt portion are dissimilar so as to produce a rotationally non-symmetrical lens. Normal beam incidence, without barrel distortion, is produced. The mesh skirt shown has two approximately equal castellations with L = 2 mm. and L<SP>1</SP> = 1 mm. in an example and with steps 7, 8 near the corners of the scanned area. Distortion is improved since for two distinctly different skirt lengths it is possible to have good horizontal geometry and good line direction beam landing, or good vertical geometry and good frame direction beam landing. In alternative embodiments a uniform skirt 5 may be provided with two or four equally spaced castellations produced on the skirt or wall anode by means of conducting tape. Four castellated portions of equal circumferential length may be of two longer and two shorter skirt portions, the former being at the top of the scanned area. In other arrangements the anode and skirt facing edges may be elliptical with non-parallel major axes, or both may be oblong with the longer axes non-parallel. Electrostatic or magnetic focusing and scanning and electrode potentials are instanced.