Control of light sources on matrix-type graphic display - uses field effect transistors to control brightness of each light source, with charge stored on capacitor as level memory

摘要

The display control is incorporated in a matrix display with each light source (4) supplied through its own power switch (8). e.g. an FET. The FET is controlled by a logic circuit (1) connected at its gate, the logic circuit being addressed by appropriate addressing circuits to allow activation by the central microprocessor based controller of individual light sources to make up the image. The logic circuit incorporates a two-position switch which allows a capacitor (11) connected to the FET gate to have applied to it a voltage representing the individual brightness required. This potential is then applied at the required moment to the gate of the FET. USE/ADVANTAGE - Allows use of grey scales in matrix format luminous displays used in large display panels, while retaining simple circuit configuration.