US 6,184,967 B2Granted

Pressure-insensitive liquid crystal cell

AssigneeEmt AG

InventorsSven T. Lagerwall, Anatoli A. Muravski, Sergei Ye Yakovenko, Viktor A. Konovalov, Anatoli A. Minko, Valeri P. Tsarev

Life of this patent

Estimating the term…

patentgrep

Loading patent…

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 μm, 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. L is so selected in dependance on current values of d and b that, when applying a pressure P on the first plate (1), a maximum relative deflection Δd/d, caused by the pressure P on the first plate between the spacers satisfies condition (A): Δd/d=PL4/4Eb3d≦G, where G is equal to the value of expression (B), representing a relative compression of the spacers caused by the same pressure P, for a case where the degree of surface coverage s assumes the above-mentioned minimum value (B): Δh/h=P/sE.

Claims27

Dependent claims

A nematic liquid crystal cell, comprising two electrode-equipped (5, 6) plates (1, 2) which are arranged at a predetermined distance from each other to define an inner cavity (C) and of which at least a first plate (1) is transparent and has a thickness b which does not exceed 1 mm;

and a modulus of elasticity E;
a liquid crystal layer (3) sealed in said cavity and containing nematic material and having a thickness d corresponding to a height of the cavity;
and spacers (11) fixed in said cavity and having a height h corresponding to the thickness d of said layer, said spacers being distributed over the cavity with a spacing L and having substantially the same modulus of elasticity E as said first plate, characterised in that the spacers (11), at least in one direction, have a width not exceeding 50 μm;
that a degree of surface coverage s by supporting areas of said spacers (11) on said first plate (1) exceeds or is equal to 1%;
and that the value of L is so selected in dependence on current values of d and b that, when applying a pressure P on said first plate (1), a maximum relative deflection Δd/d, caused by said pressure P, of said first plate between the spacers satisfies the following condition:
Δ ⁢ ⁢ d d = PL 4 4 ⁢ Eb 3 ⁢ d ≤ G1 ( A )
where G1 is equal to or lower than a value of the following expression (B), representing a relative compression of the spacers (11), caused by said pressure P, for a case where the degree of surface coverage s assumes its minimum value of 1%:
Δ ⁢ ⁢ h h = P sE . ( B )

5 more elements

A smectic liquid crystal cell, comprising two electrode-equipped (5, 6) plates (1, 2) which are arranged at a predetermined distance from each other to define an inner cavity (C) and of which at least a first plate (1) is transparent and has a thickness b not exceeding 1 mm, and a modulus of elasticity E;

a liquid crystal layer (3) sealed in said cavity and containing smectic material and having a thickness d corresponding to a height of said cavity;
and spacers (11) which are fixed in said cavity and the height h of which corresponds to the thickness d of said layer, said spacers being distributed over the cavity with a spacing L and having substantially the same modulus of elasticity E as said first plate, characterised in that the spacers (11), at least in one direction, have a width not exceeding 50 μm;
that a degree of surface coverage s by the supporting areas of said spacers (11) on said first plate (1) exceeds or is equal to 2%;
and that the value of L is so selected in dependence on current values of d and b that, when applying a pressure P on said first plate (1), a maximum relative deflection Δd/d, caused by said pressure P, of said first plate between said distances satisfies the following condition:
Δ ⁢ ⁢ d d = PL 4 4 ⁢ Eb 3 ⁢ d ≤ G2 ( A )
where G2 is equal to a value of the following expression (B), representing a relative compression of said spacers caused by said pressure P, for a case where the degree of surface coverage s assumes its minimum value of 2%;
Δ ⁢ ⁢ h h = P sE . ( B )

4 more elements

Dependencies are inferred from the claim text.