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US 6,587,171 B1Granted
Angle of view of a LCD screen by a novel birefringent film stacking
AssigneeThomson-CSF Sextant
InventorsLaurent Georges, Laurent Bignolles
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AssigneeThomson-CSF Sextant
InventorsLaurent Georges, Laurent Bignolles
Estimating the term…
The present invention relates to a display device with a liquid-crystal cell comprising a twisted nematic liquid-crystal layer (40) placed between two crossed polarizers (46, 48) and comprising, between the liquid-crystal layer and at least one of the polarizers, a structure for compensating for the variations in contrast of the cell according to the angle of observation. This structure comprises at least two superposed negative uniaxial media such that the extraordinary optical axis of one medium (44, 42) is parallel to the normal to the cell and that of the other medium (43, 41) is inclined with respect to this normal on the one hand and with respect to the plane of the cell on the other. This compensating structure includes an additional layer (50, 49) of a positive uniaxial birefringent material.
A display device with a liquid-crystal cell comprising a twisted nematic liquid-crystal layer placed between two crossed polarizers and comprising, between the liquid-crystal layer and at least one of the polarizers, a structure for compensating for the variations in contrast of the cell according to the angle of observation, which structure comprises at least two superposed negative uniaxial media such that the extraordinary optical axis of one medium is parallel to the normal to the cell and that of the other medium is inclined with respect to this normal on the one hand and with respect to the plane of the cell on the other, characterized in that the compensating structure includes an additional layer of a positive uniaxial birefringent material.
Dependencies are inferred from the claim text.