Multi-Gap Multicolor Parallel Oriented Nematic Liquid Crystal Displays
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Disclosed is a multicolor parallel oriented nematic Liquid Crystal Display (LCD) using multi-gap conditions to improve the display contrast ratio and grey scale performance.
Multi-Gap Multicolor Parallel Oriented Nematic Liquid
a multicolor parallel oriented nematic Liquid
Crystal Display (LCD) using multi-gap conditions to improve the
display contrast ratio and grey scale performance.
In the present disclosed parallel oriented
geometry, a multi-gap condition is used in which the cell gap for
each color is selected to give a perfect black at that color at the
non-select state, when observed at normal incidence between crossed
polarizers. In general, to give a zero optical transmission at
field-off state, the cell gap d for a light of wavelength &lambda.
should be set at d = (n + 1/2) &lambda. / (n sub e - n sub o), where
n = 0, 1,2,3,..., n sub o and n sub e respectively, the ordinary and
extradinary indices of refraction for the liquid crystal. In
addition, an excellent grey scale performance is obtained in the
multi-gap LCD for all the color cells, with an operation voltage
range of more than 6 volts. For the liquid crystal alignment, the
pretilt angle at the two surfaces can be of different values. This
includes the hybride oriented nematic LCDs in which the LC
orientation at one surface is close to the parallel alignment and at
the other surface is close to or equal to vertical alignment.