The Journal of The Institute of Image Information and Television Engineers
Online ISSN : 1881-6908
Print ISSN : 1342-6907
ISSN-L : 1342-6907
Multi-Gray-Scale Drive Method for TFT-LCDs with Binary-Values Using an Alternating Voltage Drive Method
Hisao Okada
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Keywords: TFT-LCD
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1997 Volume 51 Issue 4 Pages 575-582

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Abstract
Digital drive systems for TFT-LCDs generally require multi gray-scale voltage sources. This paper proposes a multi-gray-scale drive method with binary values using an alternating voltage drive method : in place of gray-scale voltage sources, gray-scale signals that are digital signals are input to the drivers. A gray-scale signal is the signal that has a duty ratio whose average value is equal to the gray-scale voltage in the conventional drive system. A drive composes waveforms whose average values correspond to the data by combining the gray-scale signals and outputs them via output buffers. As the gray-scale signals can be generated by the same ASIC generating control signals, the circuitry of the drive system can be greatly simplified. We have developed a 4-bit drive system by using this method and have applied it to mass-produced modules. We have also developed a prototype 6-bit drive system and have showed that this method is applicable to generating 64 gray scales.
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