Driving method for ferro-electric liquid crystal optical modulation device

A driving method for an optical modulation device having a plurality of picture elements arranged in the form of a matrix and comprising scanning lines, data lines spaced apart from and intersecting with the scanning lines, and a chiral smectic liquid crystal interposed between the scanning lines and the data line, each of the intersections between the scanning lines and the data lines forming one of said plurality of picture elements;

• said driving method comprising:
• a first step wherein voltage signals are simultaneously applied to the scanning lines and the data lines for providing a voltage exceeding a first threshold voltage of the chiral smectic liquid crystal for causing the chiral smectic liquid crystal to assume a first orientation state at the intersections of the scanning lines and the data lines;
• and a second step wherein a scanning selection signal is applied to a scanning line, and data signals are applied to the data lines, said data signals comprising an information signal in combination with the scanning selection signal for providing either a voltage of the other polarity exceeding a second threshold voltage of the chiral smectic liquid crystal for causing said chiral smectic liquid crystal to assume a second orientation state in combination with the scanning selection signal, or a voltage not exceeding the second threshold voltage, and an auxiliary signal following the information signal in phase with the scanning selection signal;
• said auxiliary signal, in combination with the scanning non-selection signal applied to a non-selected scanning line, providing an inversion preventing voltage at a picture element on the non-selected scanning line before the application period of a voltage of one and the same polarity appearing at the picture element while it is not on a selected scanning line reaches a period beyond which the first or second orientation state of the picture element on the non-selected scanning line formed when the picture element was placed on a selected scanning line is inverted due to said voltage of one and the same polarity, the inversion preventing voltage being a voltage of a polarity opposite to that of said voltage of one and the same polarity;
• the voltage signals applied to the scanning lines and the data lines in the first step having polarities opposite to those of the scanning selection signal and the information signal, respectively, applied in the second step with respect to the voltage applied to the non-selected scanning line;
• the voltage signals applied to the scanning lines and the data lines in the first step having mutually opposite polarities with respect to the voltage applied to the non-selected scanning line.

An optical modulation device having a plurality of picture elements arranged in a matrix and comprising scanning lines, data lines spaced apart from and intersecting with the scanning lines, and a chiral smectic liquid crystal assuming a first orientation state or a second orientation state depending on the direction of an electric field applied thereto interposed between the scanning lines and the data lines, each of the intersections between the scanning lines and the data lines forming one of said plurality of picture elements;

• said optical modulation device comprising means for effecting:
• a step of forming an image area comprising picture elements, wherein the chiral smectic liquid crystal assumes the first orientation state by application of a voltage of one polarity, exceeding a first threshold voltage of the chiral smectic liquid crystal and picture elements, wherein the chiral smectic liquid crystal assumes the second orientation state by application of a voltage of the other polarity exceeding a second threshold voltage of the chiral smectic liquid crystal, the image area comprising a rewriting region and a non-rewriting region;
• a first step wherein, in the rewriting region, a voltage of one polarity exceeding the first threshold voltage of the chiral smectic liquid crystal is applied to the intersections of a scanning line and the data lines;
• and
• a second step wherein a scanning selection signal is applied to a scanning line in the rewriting region, data signals are applied to data lines in the rewriting region, said data signals comprising an information signal in combination with the scanning selection signal for providing either a voltage of the other polarity exceeding the second threshold of voltage or a voltage not exceeding the second threshold, and an auxiliary signal following the information signal, and a voltage of the same voltage level as a scanning non-selected signal applied to a non-selected scanning line in the rewriting region is applied to scanning lines outside the rewriting region;
• the auxiliary signal, in combination with the scanning non-selection signal applied to a non-selected scanning line, providing an inversion preventing voltage at a picture element on the non-selected scanning line before the application period of a voltage of one and the same polarity appearing at the picture element while it is not on a selected scanning line reaches a period beyond which the first or second orientation state of the picture element formed when the picture element was placed on a selected scanning line is inverted due to said voltage of one and the same polarity, the inversion preventing voltage being a voltage of opposite polarity to that of said voltage of one and the same polarity.

An optical modulation device having a plurality of picture elements arranged in the form of a matrix and comprising scanning lines, data lines spaced apart from and intersecting with the scanning lines, and a chiral smectic liquid crystal interposed between the scanning lines and the data lines, each of the intersections between the scanning lines and the data lines forming one of said plurality of picture elements;

• said optical modulation device comprising means for effecting:
• a first step wherein voltage signals are simultaneously applied to the scanning lines and the data lines for providing a voltage, exceeding a first threshold voltage of the chiral smectic liquid crystal for causing the chiral smectic liquid crystal to assume a first orientation state, at the intersections of the scanning lines and the data lines;
• and a second step wherein a scanning selection signal is applied to a scanning line, data signals are applied to the data lines, said data signals comprising an information signal in combination with the scanning selection signal for providing either a voltage of the other polarity exceeding a second threshold voltage of the chiral smectic liquid crystal for causing said chiral smectic liquid crystal to assume a second orientation state in combination with the scanning selection signal, or a voltage not exceeding the second threshold voltage, and an auxiliary signal following the information signal in phase with the scanning selection signal;
• said auxiliary signal, in combination with the scanning non-selection signal applied to a non-selected scanning line, providing an inversion preventing voltage at a picture element on the non-selected scanning line before the application period of a voltage of one and the same polarity appearing at the picture element while it is not on a selected scanning line reaches a period beyond which the first or second orientation state of the picture element on the non-selected scanning line formed when the picture element was placed on a selected scanning line is inverted due to said voltage of one and the same polarity, the inversion preventing voltage being a voltage of a polarity opposite to that of said voltage of one and the same polarity;
• the voltage signals applied to the scanning lines and the data lines in the first step having polarities opposite to those of the scanning selection signal and the information selection signal, respectively, applied in the second step with respect to the voltage applied to the non-selecting scanning line;
• the voltage signals applied to the scanning lines and the data lines in the first step having mutually opposite polarities with respect to the voltage applied to the non-selected scanning line.