GRAY-SCALE STEPPED RAMP GENERATOR WITH INDIVIDUAL STEP CORRECTION

摘要

Pixel luminance of an electroluminescent display panel (22) is controlled by a row driver (24) applying a voltage equal to the panel's threshold voltage, and column drivers (26) applying the voltage value above the threshold voltage to bring the pixel (30) to the desired luminance. Each column driver (26) independently samples a stepped ramp voltage signal at its own predetermined time selected as a function of the desired luminance. Each column driver (26) then holds the sampled voltage value, and applies to its corresponding column electrode at the appropriate time a voltage equal to the sampled voltage value. The voltage rate of change of each individual step of the stepped ramped voltage signal can be controlled to vary the luminance levels, and to uniformly separate each of the luminance levels.