The magnetooptic bubble display

Abstract

The various factors that affect the properties of magneto-optic (M/O) bubble displays which use bismuth substituted iron garnets are discussed. A composite bias magnet-ferrite drive coil assembly is described which allows optical access to the display chip. The drive coils required 300 mW to produce an in-plane field of 30 Oe when operated at 10 kHz, and the bias field was uniform to ± 1.5% over an area of radius equal to 1/10 that of the bias magnet. Also discussed is the brightness and heating of the display. A screen brightness of 160 candelas/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is possible using a X20 projection lens, and the temperature rise of the display chip could be less than 1°C if adequate heat sinking were used. Finally a prototype hand-held display is described which contains a 1.3 k bit capacity display chip. Examples of characters written into that chip are given.