Liquid crystal cells – elements and systems – Liquid crystal system – Stereoscopic
Reexamination Certificate
2002-03-06
2004-05-11
Chowdhury, Tarifor R. (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal system
Stereoscopic
C349S096000, C359S462000, C359S464000, C359S465000
Reexamination Certificate
active
06734923
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 2001-11617, filed on Mar. 7, 2001, which is hereby incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a stereoscopic liquid crystal display device using a liquid crystal polymer film and fabricating method thereof.
2. Discussion of the Related Art
In normal vision, human eyes perceive views of the world from two different perspectives due to their spatial separation. The spatial separation between typical eyes is about 65 mm. In order to assess the distance between objects, the brain integrates the two perspectives obtained from each eye. In order to provide a display, which is effective in displaying three-dimensional (3-D) images, it is necessary to recreate this situation to the observer. That is, supplying a so-called “stereoscopic pair” of images to the observer's eyes.
The technology expressing the 3-D images can be divided according to the display method, the viewpoint, whether or not the glasses are adopted, the structure of the system, and the condition of observation. Especially, the 3-D displays using the parallax between the right and left eyes may be classified into two types according to whether or not the glasses are adopted: stereoscopic displays and autostereoscopic displays. Stereoscopic displays have polarization type and time division type. Autostereoscopic displays have barrier type and lenticular type.
Stereoscopic displays typically display both of the images over a wide viewing area. The views are encoded by color, polarization state, and time of the display. A filter system of glasses worn by the observer separates the views; thereby each eye sees only the view that is intended for it. That is, the right and left eyes have different views.
Autostereoscopic displays present a spatial image to the viewer without the use of glasses, goggles or other viewing aids. Instead, the two views are only visible from defined regions of space. A “viewing region” is a term described as the region of space in which an image is visible across the whole display active area. If the observer is situated such that one eye is in one viewing region and the other eye is in the other viewing region, then a correct set of views is seen and a 3-D image is perceived by the observer. In autostereoscopic displays, an image splitter and a cylindrical lens array is combined in the conventional display device.
Stereoscopic displays can be divided into anaglyph type, concentration difference type, polarizing filter type and LCD shutter type. In anaglyph type, red and blue or red and green filters are used for the right and left lenses of the glasses, respectively. In concentration difference type, filters whose transmittances are different from each other are used for the right and left lenses of the glasses. In polarizing filter type, optical principle is used for the 3-D projection. In LCD shutter type, the right and left lenses of the glasses are alternatively shut and simultaneously, the images for the right and left eyes are alternatively displayed.
Especially in the stereoscopic displays of polarizing filter type, a polarizing plate is formed on the surface of the display, thereby light parallel to the transmission axes of the polarizing filters of the right and left lenses, respectively, is emitted. The transmission axis of the polarizing filter is called the polarization axis. The polarizing plate has a plurality of micro-polarizing plates whose polarization axes are parallel to the corresponding polarization axes of the polarizing filters of the right and left lenses. Since light emitted from the plurality of micro-polarizing plates are received by the right and left lenses of the glasses respectively, the 3-D images are perceived by the binocular parallax of the viewer.
FIGS. 1A and 1B
are perspective views of polarizing plates attached to a stereoscopic device of a conventional polarizing filter type and
FIG. 1C
is a perspective view of conventional polarizing glasses.
In
FIGS. 1A
to
1
C, polarizing plates “A” and “B” are composed of a plurality of micro-polarizing plates
32
a
and
32
b
whose polarization axes are parallel to the corresponding polarization axes
33
a
and
33
b
of the polarizing film attached to the right and left lenses of the polarizing glasses
30
in mosaic and stripe shapes, respectively. The polarizing plates “A” and “B,” having a plurality of micro-polarizing plates
32
a
and
32
b
, are formed through fabrication processes of
FIGS. 2A
to
2
F.
FIGS. 2A
to
2
F are schematic cross-sectional views showing fabrication processes of a conventional polymer polarizing film taken along a line II—II of
FIGS. 1A and 1B
.
In
FIG. 2A
, a plurality of first micro-polarizing regions “C” and second micro-polarizing regions “D” are defined on an entire surface of a substrate
34
.
In
FIG. 2B
, a polymer polarizing film
36
having a first polarization axis
38
a
is formed on the substrate
34
. Generally, the polymer polarizing film
36
is made by adsorbing iodine (I) or dichromatic dyes into one-directionally elongated poly vinyl alcohol (PVA) film. Here, a transmission axis of the polarizing film, i.e., a polarization axis is perpendicular to the elongated direction of the PVA film. In ambient light, only linearly polarized light parallel to the polarization axis of the polarizing film is transmitted.
In
FIG. 2C
, after forming a photoresist (PR) layer
39
on the polymer polarizing film
36
, an exposure process is performed with a mask
40
over the polymer polarizing film
36
. The mask
40
has a plurality of transmission regions “E” and a plurality of shield regions “F”. The PR is divided into positive type and negative type. For the positive type, the PR of the exposed region is removed by the developing solution. For the negative type, the PR is not removed. In this description, the case using the PR of the positive type is explained. That is, the mask
40
is disposed over the substrate
34
so that the plurality of shield regions “F” corresponds to the plurality of first micro-polarizing regions “C”.
In
FIG. 2D
, after developing, a PR pattern
39
a
is formed only at the plurality of first micro-polarizing regions “C”.
In
FIG. 2E
, the polymer polarizing film of the plurality of the second micro-polarizing regions “D” is etched by, for example, a chemical etching method (water:ethyl alcohol=30%:70%), photochemical etching method, excimer laser etching method or reactive ion etching method. Then, the PR pattern
39
a
on the plurality of first micro-polarizing regions “C” is removed by the stripper. Through this photolithography process, a first polarizing film
43
having a plurality of first micro-polarizing plates
42
a
at the plurality of first micro-polarizing regions “C” is formed.
In
FIG. 2F
, a second polarizing film
45
having a plurality of second micro-polarizing plates
42
b
at the plurality of second micro-polarizing regions “D” is formed on another substrate
40
by repetition of processes of
FIGS. 2A
to
2
E. The polarization axis
38
b
of the second polarizing film
45
is perpendicular to the polarization axis
38
a
of the first polarizing film
43
on the plane parallel to the substrate.
In
FIG. 2G
, a polymer polarizing film
47
having the plurality of first and second micro-polarizing plates
42
a
and
42
b
whose polarizing axes
38
a
and
38
b
are perpendicular to each other is formed by attaching the first and second polarizing films
43
and
45
.
The polymer polarizing film
47
can be fabricated by other methods, and one example of a fabrication method will be explained as follows.
FIGS. 3A
to
3
E are schematic cross-sectional views showing other fabrication processes of a conventional polymer polarizing film.
In
FIG. 3A
, through exposure and developing processes, a PR pattern
39
a
is formed on a PVA film
36
at a plurality of first micro-polarizing regions “C”
Hong Hyung-Gi
Jung Jin-Hee
Kwon Soon-Bum
Caley Michael H.
Chowdhury Tarifor R.
LG.Philips LCD Co. , Ltd.
McKenna Long & Aldridge LLP
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