Magnetooptical display element using permalloy films

Nixie tubes and CRT display elements are useful as a numerical indicator, but these require a large volume and comparatively high voltage source. Magnetooptical display elements provide a flat panel display with memory and are quite adaptable to batch-fabrication techniques. This paper describes the numerical display elements for the solid-state panel display, utilizing magnetic thin films. The display elements are composed of the magnetic thin-film, insulator, and conductor layers, and these layers are evaporated onto a glass substrate. A numerical display pattern is determined by the state of magnetization of the channel pieces, that is, local switching in the film, which can be accomplished by the drive pulse fields. The local switching is controllable by pulse current flowing through the selected drive lines. The local switching pattern in the film can be observed as a dark-on-bright pattern by the Kerr magneto-optic effect. The pattern, written by the drive currents, is memorized until subsequent alteration is performed. The drive current is a 1-μs 300-mA pulse and the bias field applied along the easy axis is 2.5 Oe. The contrast ratio obtained is 1:3. The size of numerical display pattern is 1 × 3.6 mm, and substrate is 10 × 10 mm no. 3 Corning glass.