Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1997-07-21
2001-07-17
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S158000, C349S122000
Reexamination Certificate
active
06262787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a PF-LCD (polymer film liquid crystal display device) which is a liquid crystal display device using substrates implemented by polymer films, and which particularly delimits a film composition and thickness of upper and lower polarizing plates and/or a thickness of a cohesive agent so as to improve irregularities of colors of the PF-LCD.
2. Discussion of the Background
FIG. 1
shows a background art apparatus of a PF-LCD. In this device in
FIG. 1
, two polymer film substrates
10
are provided. Further, a lower polarizing plate
16
is formed on a lower surface of a lower of the polymer film substrates
10
. A reflective plate
19
is formed adjacent to the lower polarizing plate
16
, on an opposite face as the shown lower polymer film substrate
10
. An alignment layer
15
which includes transparent electrodes
17
is formed on a surface of the lower shown polymer film substrate
10
. A central portion of the PF-LCD device includes a liquid crystal layer
13
and spacers
18
. Formed above the upper shown polymer film substrate
10
is a phase plate
12
and then an upper polarizing plate
14
.
A concern with such a PF-LCD device as shown in
FIG. 1
is that a thickness of the liquid crystal layer
13
must be maintained to be even. If liquid crystal layer
13
is not maintained to have an even thickness, irregularities in color result from any unevenness in the thickness of the liquid crystal layer
13
.
The device as shown in
FIG. 1
utilizes polymer films for the substrates
10
, and also particularly for the upper polarizing plate
14
and lower polarizing plate
16
, to assure an ultra-thin and light weight design. However, the use of such polymer films for the upper polarizing plate
14
and the lower polarizing plate
16
results in such an upper polarizing plate
14
and lower polarizing plate
16
being somewhat flexible, in comparison with a device which may utilize a rigid glass structure. The utilization of polymer films for the upper polarizing plate
14
and lower polarizing plate
16
provides the benefits of the device of
FIG. 1
being ultra-thin and light weight, but provides the drawbacks that variations in a liquid crystal layer
13
are more apt to occur, i.e., a thickness of the liquid crystal layer
13
may not be as uniform as desired.
One manner in addressing this issue, as disclosed in Japanese patent publication no. 06-67172, by the Applicants of the present application, is to include at least one layer of plastic film as a reinforcing plate at an outer layer of the PF-LCD panel to reduce any deformation of the panel, and thereby to reduce any nonuniformity of the liquid crystal layer
13
. Such a deformation of the panel may be particularly appreciable from changes in temperature and humidity.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a novel polymer film liquid crystal display device which can ensure a uniformity in a liquid crystal layer. In this way, the device of the present invention can improve irregularities of colors appearing on panels of the PF-LCD.
The present invention achieves these objectives by forming a novel liquid crystal display device which includes a liquid crystal layer formed between a pair of polymer film substrates. A pair of polarizing plates are formed on outer surfaces of each of the substrates. Moreover, in the present invention a thickness of each of the substrates D (&mgr;m) and a thickness of each of the polarizing plates L (&mgr;m) satisfy D=L±30&mgr;m.
Moreover, as a further feature of the present invention to achieve the above-noted objects, a thickness of protecting layers provided in each polarizing plate may be 50 &mgr;m or less and a thickness of a polarizer of each polarizing plate may be 20 &mgr;m.
As a further feature of the present invention to achieve the above-noted objects, a cohesive layer is provided to attach each polarizing plate to the liquid crystal device, and such a cohesive layer may have a thickness of at least 50 &mgr;m.
In a further structure of the present invention to achieve the above-noted objects, a spacer layer can be provided in conjunction with the cohesive layer.
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Kamoi Sumio
Kikuchi Hisashi
Miyamoto Isao
Nguyen Dung
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
Sikes William L.
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