Bistable reflective cholesteric liquid crystal displays utilizing super twisted nematic driver chips

A method for addressing a cholesteric liquid crystal display which has a pair of opposed substrates, one of the substrates having a first plurality of electrodes, the other substrate having a second plurality of electrodes oriented in a direction different than the first plurality of electrodes, the substrates having cholesteric liquid crystal material disposed therebetween to form a pixel at each intersection of the first and the second plurality of electrodes, the first plurality of electrodes having at least a first driver coupled thereto and the second plurality of electrodes having at least a second driver coupled thereto, the method comprising the steps of:

• applying a plurality of voltage input waveforms to the first driver and the second driver, wherein said voltage input waveforms are about 60 volts RMS or less;
• selectively transmitting said plurality of voltage input waveforms through the first and the second drivers to generate respective first and second output waveforms;
• combining said first and second output waveforms at the intersecting electrodes to generate a pixel waveform that drives the cholesteric liquid crystal material to the desired appearance, wherein said step of combining further comprises the steps of:
• applying preparation voltages to each pixel for driving the cholesteric material into a homeotropic texture;
• applying hold voltages to each pixel wherein at least one of said hold voltages is different than said preparation voltages, to maintain the cholesteric material in the homeotropic texture;
• applying selection voltages to each pixel for predisposing the cholesteric material;
• and
• applying evolution voltages to each pixel to allow the predisposed cholesteric material to relax into either a planar or a focal conic texture.

A driving circuit for a reflective bistable cholesteric liquid crystal display which includes one substrate having a first plurality of electrodes opposed by another substrate having a second plurality of electrodes, wherein the intersection of the first and the second plurality of electrodes with bistable cholesteric liquid crystal material disposed therebetween form a plurality of pixels, the driving circuit selectively applying voltages to the first and the second plurality of electrodes to control the appearance of each pixel, the driving circuit comprising:

• at least one common driver coupled to the first plurality of electrodes, each common driver having a first and a second common frame switch, each said common frame switch having a high input and a low input, said first and second frame switches linked to one another by a common frame line, said high and low inputs connected to a plurality of common data switches, each having a common output, said first common frame switch receiving a first and a second common voltage input and said second common frame switch receiving a third and a fourth common voltage input connected to each other, wherein said common frame line is toggled to selectively pass through said common voltage inputs for use as said common voltage output from each said common data switch;
• and
• at least one segment driver coupled to the second plurality of electrodes, said at least one segment driver having a plurality of segment voltage outputs which are selectively applied to the second plurality of electrodes to drive the cholesteric liquid crystal material to a desired texture.

A method for addressing a liquid crystal display having a plurality of common electrodes orthogonally positioned with respect to a plurality of segment electrodes with cholesteric liquid crystal material disposed therebetween, the method comprising the steps of:

• connecting at least one common driver to the plurality of common electrodes;
• connecting at least one segment driver to the plurality of segment electrodes;
• and
• toggling a pair of frame switches in each said common and segment driver such that a first of said pair of frame switches applies one of two waveforms to the corresponding electrodes or such that a second of said pair of frame switches applies an arbitrary waveform to the corresponding electrodes.

A driving circuit for a reflective bistable cholesteric liquid crystal display which includes one substrate having a first plurality of electrodes opposed by another substrate having a second plurality of electrodes, wherein the intersection of the first and the second plurality of electrodes with bistable cholesteric liquid crystal material disposed therebetween form a plurality of pixels, the driving circuit selectively applying voltages to the first and the second plurality of electrodes to control the appearance of each pixel, the driving circuit comprising:

• a plurality of common drivers for generating and selectively applying voltages to the first plurality of electrodes, each said common driver having two inputs connected to each other to form a superinput;
• a plurality of segment drivers for generating and selectively applying voltages to the second plurality of electrodes;
• and
• a mode select switch coupled to each said common driver to select one of two modes to transfer a select or non-select voltage to said superinput, wherein said plurality of common drivers and said plurality of segment drives apply the voltages to drive the cholesteric liquid crystal material to a desired texture.