Magnetic matrix display device and computer system for displaying data

Abstract

A magnet for use in a magnetic matrix display has a two dimensional array of apertures between opposite poles of the magnet. The direction of the magnetic field is such that the magnet generates, in each channel, a collimating magnet field for forming electrons from a cathode into an electron beam. A `keeper`, area around the periphery of the magnet is used to improve the linearity of the field strength in the apertures from apertures at the center of the magnet to apertures at the periphery of the magnet. The `keeper`, area may have control circuits placed on the surface of that area of the magnet. The keeper area may contain apertures which are not used for collimation and into which electrons are prevented from entering by a grid electrode or by a physical blocking means.