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Symmetrical Multicolor Multi-Domain Homeotropic and Hybrid Oriented Nematic Liquid Crystal Displays using Periodic Triangular Tooth Waveform Surfaces

IP.com Disclosure Number: IPCOM000106815D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Depp, SW: AUTHOR [+3]

Abstract

Disclosed is a multicolor homeotropic oriented nematic Liquid Crystal Display (LCD), using a periodic triangular tooth waveform surface and the conventional homeotropic surface alignment to give a multi-domain LCD with a symmetrical angular optical performance.

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This is the abbreviated version, containing approximately 52% of the total text.

Symmetrical Multicolor Multi-Domain Homeotropic and Hybrid Oriented Nematic Liquid Crystal Displays using Periodic Triangular Tooth Waveform Surfaces

      Disclosed is a multicolor homeotropic oriented nematic Liquid
Crystal Display (LCD), using a periodic triangular tooth waveform
surface and the conventional homeotropic surface alignment to give a
multi-domain LCD with a symmetrical angular optical performance.

      In the present disclosed LCD device, the first substrate has a
one-dimensional periodic triangular tooth waveform surface, and the
second substrate has a conventional flat surface.  Both surfaces are
treated to give a homeotropic alignment, with or without a pretilt
angle.  The liquid crystal used should have a negative dielectric
anisotropy so that under the presence of an external field, it will
orientate perpendicular to the field direction.  The surface
alignment is homeotropic, but the liquid crystal orientation will
have an asymmetrical structure due to the triangular tooth surface.
The cell gives a complete black field-off state for all colors.
Thus, very high contrast ratio for all colors can be obtained, and
the viewing angle is significantly improved.  Also, an excellent grey
scale performance is obtained for all colors, with a symmetrical
angular optical performance for an operation voltage range of more
than 7 volts.

      In general, the one-dimensional periodic waveform substrates
can be fabricated by the following three methods, where the
replication method gives a relatively inexpensive technique to make
large quantities of substrates and is more appropriate to fabricate
the substrates for the present LCD application.

1.  Using direct cutting - The substrate can be made by direct
    cutting of the substrate to the periodic surface waveform.

2.  Using photosensitive glass - The substrate can be made using
    photosensitive glass.  First, the photosensitive glass is exposed
    to the ultraviolet (uv) light with the desired periodic waveform
    pattern.  After the uv exposition, the pattern is developed by
    heat treatment.  Because of a pronounced difference in chemical
    solubility between the exposed and unexposed areas, the expose
    pattern can be etched out with hydrofluoric acid.  An exact copy
    of the master or negative was then obtained through which t...