Abstract: Example embodiments disclosed herein relate to the stabilization of the orthoconic state in orthoconic antiferroelectric liquid crystal devices. According to some of the example embodiments, the stabilization may be obtained by tuning a device cell as well as material parameters. The orthoconic state may be stabilized by means of the cell surfaces, electric fields, and/or polymer-stabilization, and combinations thereof, under selected conditions. The example embodiments presented herein advances several new working modes as well as new types of applications of orthoconic antiferroelectric liquid crystals.

Abstract: Example embodiments presented herein may be directed towards an antiferroelectric liquid crystal (AFLC) device and a method for writing greyscale in the AFLC device. The device may comprise two electrode substrates confining an antiferroelectric liquid crystal (AFLC) material. The method may comprise driving the AFLC device with an electrical signal, where the electrical signal does not comprise a direct current holding voltage for a writing of at least a portion of written levels of grey. The method may also comprise inducing a greyscale configuration in the AFLC device as a function of the driving, wherein the inducing is temperature independent. The method may also comprise applying a high-frequency signal, to stabilize a well-defined horizontal tilt plane of the antiferroelectric or, in particular, of the orthoconic antiferroelectric. The examples embodiments presented herein provide for fast and precise writing of greyscales in orthoconic antiferroelectrics.

Abstract: Example embodiments presented herein may be directed towards an antiferroelectric liquid crystal (AFLC) device and a method for writing greyscale in the AFLC device. The device may comprise two electrode substrates confining an antiferroelectric liquid crystal (AFLC) material. The method may comprise driving the AFLC device with an electrical signal, where the electrical signal does not comprise a direct current holding voltage for a writing of at least a portion of written levels of grey. The method may also comprise inducing a greyscale configuration in the AFLC device as a function of the driving, wherein the inducing is temperature independent. The method may also comprise applying a high-frequency signal, to stabilize a well-defined horizontal tilt plane of the antiferroelectric or, in particular, of the orthoconic antiferroelectric. The examples embodiments presented herein provide for fast and precise writing of greyscales in orthoconic antiferroelectrics.

Abstract: Example embodiments disclosed herein relate to the stabilization of the orthoconic state in orthoconic antiferroelectric liquid crystal devices. According to some of the example embodiments, the stabilization may be obtained by tuning a device cell as well as material parameters. The orthoconic state may be stabilized by means of the cell surfaces, electric fields, and/or polymer-stabilization, and combinations thereof, under selected conditions. The example embodiments presented herein advances several new working modes as well as new types of applications of orthoconic antiferroelectric liquid crystals.

Abstract: The invention relates to a liquid crystal device, comprising an antiferroelectric liquid crystal material (AFLC material) having smectic layers, and two substrates confining the AFLC material therebetween, wherein the AFLC material is uniaxial negative. Preferably, the AFLC material is uniaxial as a consequence of a surface stabilization and of a selected smectic tilt angle ? of the AFLC material. Preferably, the angle ? is in the range of 40°???50°, especially 45°. The invention also relates to electrooptic liquid crystal devices.

Abstract: The invention relates to a liquid crystal device, comprising an antiferroelectric liquid crystal material (AFLC material) having smectic layers, and two substrates confining said AFLC material therebetween, wherein said AFLC material is uniaxial negative. Preferably, the AFLC material is uniaxial as a consequence of a surface stabilization and of a selected smectic tilt angle &thgr; of said AFLC material. Preferably, said angle &thgr; is in the range of 40°<&thgr;<50°, especially 45°. The invention also relates to electrooptic liquid crystal devices.

Abstract: The invention relates to an essentially pressure-insensitive liquid crystal cell. Electrode-equipped (5, 6) plates (1, 2) are arranged at a predetermined distance from each other and define a liquid crystal layer of a thickness d. At least a first (1) of the plates is transparent and has a thickness b not exceeding 1 mm, and a modulus of elasticity E. Spacers (11) fixed in the cavity and having a height h are distributed with a spacing L and have substantially the same modulus of elasticity E as said first plate. The spacers (11) have a width not exceeding 50 &mgr;m, at least in one direction. The degree of the surface coverage s by the supporting areas of the spacers (11) on said first plate (1) exceeds or is equal to a minimum value which is dependent on the type of liquid crystal.

Abstract: The invention relates to a protective device of the type having a body (1) and a filtering unit (10) supported by said body and acting as a visor, said filtering unit being electrically shiftable between at least two light transmitting conditions and comprising, for this purpose, one or more LC cells. The filtering unit (10) is made wholly or at least to a major extent of polymer material and is designed as a panoramic visor which is darkenable over its entire area. Said one or more LC cells are in the form of a foil and extend over the entire area of the panoramic visor. The invention is of special interest for welding helmets with automatically controlled darkening.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: An electro-optical device including a chiral nematic liquid crystal disposed between flat plates treated to weakly enforce molecular orientation along one preferred direction parallel to the plates. The plates are spaced by a distance small compared to the pitch of the helix typical in a bulk of the material, or the helix compensated by additives to ensure the equivalent situation. By an externally applied electric field the liquid crystal molecular orientation is rotated in a plane parallel to the plates away from the preferred orientation an angle the sign and size of which depends on the sign and magnitude of the field. The optical axis of the liquid crystal, oriented along the molecular orientation, is thus controlled by the external electric field in such a way as to make a linear light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to fore either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combianiton non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is repsonsive to an externally applied electric field, temperature or the like to make a light valve or other electro0optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ along or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinsic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.

Abstract: A liquid crystal device including a ferroelectric liquid crystal disposed between plates treated to enforce a particular ferroelectric molecular orientation to the plates. The devices employ alone or in combination non-planar boundary conditions, polar boundary conditions, boundaries with multiple physical states, intrinic spontaneous splay distortion of the polarization orientation field, combined ferroelectric and dielectric torques, layers tilted with respect to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form either monostable, bistable or multistable states which exhibit novel electro-optic properties. The liquid crystal is responsive to an externally applied electric field, temperature or the like to make a light valve or other electro-optical device.