Transfluxor Controlled Electroluminescent Display Panels

Abstract

The feasibility of displaying images according to electrical signals using an array of electroluminescent cells magnetically controlled has been demonstrated by a working model. A transfluxor is associated with every electroluminescent cell. Each transfluxor is set by the coincidence of row and column current pulses to a level determined by the amplitude of the video signal, stores this level, and transmits energy continuously to the cell in proportion to the stored level. Both halftone and on-off control of brightness is possible. Scanning is accomplished by magnetically switching row and column conductors. The array has 1200 elements arranged in 30 rows of 40 each. The picture is uniform, exhibits good halftones, and has a maximum brightness of four foot lamberts. To obtain sufficient voltage from the transfluxor to excite electroluminescence, drive by short, fast-rising pulses is used. Light output data for such pulses were obtained and it was found that a steeper dependence of light output upon voltage, a different color spectrum, and higher efficiency resulted than is obtained with sine-wave drive. A modification using a linear transformer to couple the transfluxor and electroluminescent cell and driven by sine waves to operate as a transfluxor-tuned resonant circuit was demonstrated to be economical in driving and setting power. For some applications, the full storage afforded by a transfluxor at each picture element is not necessary. A system was investigated which uses fewer transfluxors storing only a row of picture information at a time.