Drive method for liquid crystal optical device

Claim 1

A method of driving a liquid crystal optical device comprising: providing a pair of substrates having electrodes which at least partially face each other and are formed on opposing inner surfaces; providing a liquid crystal material which is sealed between said pair of substrates, and whose molecules are initially aligned in directions parallel to each other in accordance with an aligning treatment subjected to said inner surfaces of said substrates, and an alignment state of the molecules being controlled by an electric field applied across said electrodes, said liquid crystal material having a crossover frequency at which its dielectric anisotropy becomes "0", and exhibiting a dielectric dispersion phenomenon wherein the polarity of the dielectric anisotropy-is inverted in an electric field of a frequency lower than the crossover frequency and in an electric field of a frequency higher than the crossover frequency; providing a pair of polarizing means arranged outside said liquid crystal material, polarizing axes of said polarizing means being substantially perpendicular to each other, and at least one polarizing axis intersecting the direction of the aligning treatment of said inner surfaces of said pair of substrates, at an angle falling within the range of 35° to 45°; applying a electric field to said liquid crystal material; characterized in that said applying step comprises applying, an ON electric field, which has at least an electric field for driving the liquid crystal molecules and a non-electric field, for obliquely aligning the liquid crystal molecules with respect to said pair of substrates to obtain an ON state of the device, and an OFF electric field for homeotropically aligning the liquid crystal molecules with respect to said substrates to obtain an OFF state, for controlling said liquid crystal optical device in the ON or OFF state.

Claim 2

A method of driving a liquid crystal optical device comprising: providing a pair of substrates having electrodes which at least partially face each other and are formed on opposing inner surfaces; providing a liquid crystal material which is sealed between said pair of substrates, and whose molecules are initially aligned in directions parallel to each other in accordance with an aligning treatment subjected to said inner surfaces of said substrates, and an alignment state of the molecules being controlled by an electric field applied across said electrodes, said liquid crystal material having a crossover frequency at which its dielectric anisotropy becomes "0", and exhibiting a dielectric dispersion phenomenon wherein the polarity of the dielectric anisotropy-is inverted in an electric field of a frequency lower than the crossover frequency and in an electric field of a frequency higher than the crossover frequency; providing a pair of polarizing means arranged outside said liquid crystal material, polarizing axes of said polarizing means being substantially perpendicular to each other, and at least one polarizing axis intersecting the direction of the aligning treatment of said inner surfaces of said pair of substrates, at an angle falling within the range of 35° to 45°; applying a electric field to said liquid crystal material; characterized in that said applying step comprises applying, an ON electric field, which has at least an electric field for driving the liquid crystal molecules and a non-electric field, for obliquely aligning the liquid crystal molecules with respect to said pair of substrates to obtain an ON state of the device, and an OFF electric field for homeotropically aligning the liquid crystal molecules with respect to said substrates to obtain an OFF state, for controlling said liquid crystal optical device in the ON or OFF state.

Claim 3

A method according to claim l, characterized in that the ON electric field consists of an ON operation electric field for causing the liquid crystal molecules to be obliquely aligned with respect to said pair of substrates, so as to increase an amount of transmitted light, and an ON-maintaining electric field for maintaining the liquid crystal molecules in the obliquely aligned state.

Claim 5

A method according to claim-2, characterized in that the ON operation electric field is applied to said liquid crystal material for a period of time which is equal to substantially 1/2 of a given application time of the ON electric field.