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Bi-Handedness Two-Domain Twist Nematic Cell for Active Matrix Display Application

IP.com Disclosure Number: IPCOM000105614D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Lien, SC: AUTHOR

Abstract

The basic structure of the bi-handedness two-domain twist nematic cell (BH-TDTN) and its fabrication method are disclosed. The BH-TDTN display has a nearly symmetric wide-viewing angle and good gray scale fidelity for the active matrix display application.

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Bi-Handedness Two-Domain Twist Nematic Cell for Active Matrix Display Application

      The basic structure of the bi-handedness two-domain twist
nematic cell (BH-TDTN) and its fabrication method are disclosed.  The
BH-TDTN display has a nearly symmetric wide-viewing angle and good
gray scale fidelity for the active matrix display application.

      The pixel structure and rubbing directions of the proposed
80º  bi-handedness two-domian TN cell (BH-TDTN) are shown in
the Figure.  Each pixel is divided into two domains.  One substrate,
say front substrate, is rubbed once, and rubbed upward along the
solid arrow AB.  The other substrate, say rear substrate, is rubbed
twice.  Each pixel in the real substrate is divided into upper and
lower regions.  Rubbing directions for both regions are different.
The upper region is rubbed along dashed arrow CD, the lower region is
rubbed along the dashed arrow EF.  Both rubbing directions make
80º  with respect to the rubbing direction in the front
substrate as shown in the Figure The non-chiral additive nematic
liquid crystal is used for the BH-TDTN panel.  Thus, the liquid
crystal molecules in the upper region of each pixel twist left-handed
from the direction of 10º  below the horizontal line pointing
to the right on the rear substrate to the direction of vertical down
on the front substrate.  Therefore, the upper region of each pixel
becomes left-handed 80º  twist domain.  Its lower viewing zone
points to the direction of 50º  below the horizontal line
pointing to the right.  The liquid crystal molecules in the lower
region of each pixel twist right-handed from the direction of
10º  below the horizontal line pointing to the left on the
rear substrate to the direction of vertical down on the front
substrate.  Therefore, the lower region of each pixel becomes
left-handed 80º  twist domain.  Its lower viewing zone points
to the direction of 50º  below the horizontal line pointing to
the left.  The electro-optics of the 80º  bi-handedness
two-domain TN cell will roughly be the average of those of the
horizontal and vertical viewing zones of the corresponding single
domain 80º  TN cell.  Thus, the vertical viewing zone is
greatly improved with some expense of horizontal viewing zone which
is usually much better than the vertical one.  As a result, the four
viewing zones are near symmetric.

      As an example, the fabrication procedure for the 80º
BH-TDTN panel with the pixel structure given in the Figure is as
foll...