Control of liquid crystal display visual properties to compensate for variation in the characteristics of the liquid crystal
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United States of America Patent
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Oct 20, 1992
Grant Date -
N/A
app pub date -
Oct 23, 1990
filing date -
Oct 27, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
The contrast or absolute brightness of a multiplexed LCD is maintained at its preselected value using a feedback arrangement which includes an LCD element functioning as a reference element. The reference element is not used to display information but is continually driven ON and OFF. The average transmissivity of the ON and OFF states is determined and compared with a reference value, the result of the comparison being used to control the voltage levels of the drive waveforms applied to the LCD. By selecting appropriate ratios between the ON and OFF times of the reference element, the LCD can be operated to give optimum contrast, or may have its absolute brightness varied. Control may be effected remotely by reprogramming the microprocessor which determines the timing of the drive waveforms.
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Cited Art Landscape
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