A GaP electroluminescent diode matrix display system

A prototype of a single-line alphanumeric character display system has been designed and built using GaP red electroluminescent diodes in a matrix connection for the display elements and low-power TTL integrated-circuit chips for the memory and logic functions. The display is a dot matrix of 7 rows and 72 columns and the associated shift-register memory is such as to allow great operational flexibility which includes the ability to display characters and symbols of variable width and a "rolling" mode of operation, i.e., one column of new display information is introduced periodically at the right end causing the old information to shift one column to the left. Thus, the information travels (rolls) from right to left at reading speed. This type of display system is useful for displaying short transitory messages originating from a remote centralized terminal, e.g., a telephone system in a business environment. The rolling feature allows extended messages to be shown, at reading speed, on a relatively small matrix, and the variable character width makes optimum use of the available display area. The present display serves the purpose of demonstrating feasibility but does not represent an optimum in either technology. A more optimized system using beam-leaded monolithic circuits in both technologies is briefly discussed.