Importance

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Abstract

A structure and method for controlling a liquid crystal display takes advantage of the sharp reflectance change over a small voltage change for new liquid crystal display materials, applying ON and OFF pixel voltages very close to the transition voltage of the liquid crystal material and regulating the applied voltage to remain reliably near and on the desired side of this transition voltage. Also, a net zero DC voltage across pixels of the crystal is maintained using a switching mode close to half the frequency of prior art modes. Driving voltages are provided by a switching regulator rather than the prior art voltage divider, resulting in a significant reduction in operating power. The preferred switching regulator generates only three additional voltages for driving rows and columns of the display, in contrast to the five generated voltages of the prior art voltage divider. An on/off voltage regulator alternately provides or does not provide power to a primary coil, thereby controlling voltage across capacitors associated with secondary coils. This gives accurate voltage control over a wide range of display loads. This voltage regulator is controlled preferably by the low voltage applied across pixels during the time when the pixels are not in the selected row, that is, during the time when the logic state of a pixel is not provided to the pixel.

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First Claim