Fast switching 270.degree. twisted nematic liquid crystal device and eyewear incorporating the device

A method of making a fast switching liquid crystal device having a lack of substantial textural nonuniformities, and a neutral colored, transmissive off state, and which does not require a bias voltage in the off state, the method comprising the steps of:

• arranging a pair of substantially parallel, transparent substrates, each of the substrates having an interior surface and an exterior surface, wherein the substrates are separated by a distance, thereby defining a gap between the substrates;
• forming a transparent, conductive electrode on the interior surface of each of the substrates, each of the electrodes having a surface in contact with the interior surface of each of the substrates and an interior surface facing away from the interior surface of each of the substrates, wherein the interior surface of each of the electrodes is conditioned to define a preferred direction, and further, wherein the preferred direction of one of the electrodes is substantially perpendicular to the preferred direction of the other of the electrodes;
• inserting a nematic liquid crystal material having a director axis, the liquid crystal material being contained within the gap, wherein the director axis at each of the electrodes is aligned with the preferred direction of each of the electrodes, and wherein the conditioning of the electrodes causes the director axis of the liquid crystal material to assume a tilt angle with respect to the interior surface of each of the electrodes;
• mixing an optically active additive with the liquid crystal material in an amount sufficient to impart a pitch equal to between one and two times the gap, and to cause the liquid crystal material to assume a helical structure, wherein the helical structure of the liquid crystal material is such that it assumes a twist of 270 degrees in the transmissive off state, and further, wherein the tilt angle between the director axis of the liquid crystal material and the interior electrode surface is maintained along the helical structure of the liquid crystal material;
• and
• arranging a polarizing filter on the exterior surface of each of the substrates, wherein the polarizing filters have substantially perpendicular polarization axes and the polarizing axis of one of the polarizing filters is either substantially parallel or perpendicular to the direction of alignment of the director axis of the liquid crystal material at the interior surface of the electrode closest to that polarizing filter.

A pair of eyewear for viewing a field-sequential stereoscopic display, comprising:

• a frame;
• a pair of fast switching liquid crystal shutter assemblies arranged in the frame, wherein each of the pair of shutter assemblies further comprises:
• a pair of substantially parallel, transparent substrates, each of the substrates having an interior surface and an exterior surface, wherein the substrates are separated by a distance, thereby defining a gap between the substrates;
• a transparent, conductive electrode deposited on the interior surface of each of the substrates, each of the electrodes having a surface in contact with the interior surface of each of the substrates and an interior surface facing away from the interior surface of each of the substrates, wherein the interior surface of each of the electrodes is conditioned to define a preferred direction, and further, wherein the preferred direction of one of the electrodes is substantially perpendicular to the preferred direction of the other of the electrodes;
• a nematic liquid crystal material having a director axis, and contained within the gap, wherein the director axis at each of the electrodes is aligned with the preferred direction of each of the electrodes, and wherein the conditioning of the electrodes causes the director axis of the liquid crystal material to assume a tilt angle with respect to the interior surface of each of the electrodes;
• an optically active additive mixed with the liquid crystal material in an amount sufficient to impart a pitch equal to between one and two times the gap, and to cause the liquid crystal material to assume a helical structure, wherein the helical structure of the liquid crystal material is such that it assumes a twist of 270 degrees in the transmissive off state, and further, wherein the tilt angle between the director axis of the liquid crystal material and the interior electrode surface is maintained along the helical structure of the liquid crystal material;
• and
• a polarizing filter arranged on the exterior surface of each of the substrates, wherein the polarizing filters have substantially perpendicular polarization axes and the polarizing axis of one of the polarizing filters is either substantially parallel or perpendicular to the direction of alignment of the director axis of the liquid crystal material at the interior surface of the electrode closest to that polarizing filter;
• and
• a means for driving the shutter assemblies, substantially 180 degrees out of phase with respect to each other, so that the shutter assemblies alternately enter a transmissive state.