Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-10-17
2004-10-19
Nguyen, Dung T. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S112000
Reexamination Certificate
active
06806926
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection-type color liquid crystal display apparatus and a method for manufacturing the same. More particularly, the invention relates to a reflection-type color liquid crystal display apparatus and a method for manufacturing the same, wherein a color filter is provided on a substrate where a liquid crystal driving element is formed.
2. Description of the Related Art
As display apparatuses for various information apparatuses or the like, reflection-type color liquid crystal display apparatuses are widely used.
FIG. 1
is a sectional view showing a structure of one example of a conventional reflection-type color liquid crystal display apparatus. The conventional reflection-type color liquid crystal display apparatus comprises, as shown in
FIG. 1
, a liquid crystal driving element formation substrate
101
on which a thin film transistor (TFT) serving as a switching element (a driving element) for driving a liquid crystal is formed, an opposite substrate
102
which is opposed to the substrate
101
, and a liquid crystal
103
sandwiched between both the substrates
101
and
102
.
The liquid crystal driving element formation substrate
101
comprises, as shown in
FIG. 1
, a transparent insulation substrate
104
made of glass or the like; a gate electrode
105
and a reflection plate
106
formed of aluminum, aluminum alloy or the like, which is formed on the transparent substrate
104
; a gate insulation film
107
formed of silicon nitride or the like, which is formed on the gate electrode
105
and the reflection plate
106
; a semiconductor layer
108
formed of an amorphous silicon or the like, which is formed on the gate insulation film
107
above the gate electrode
105
; a drain electrode
109
and a source electrode
110
formed of chromium or the like, which are connected to both ends of the semiconductor layer
108
, respectively; and an insulation protection film
111
formed of silicon nitride or the like, which covers the drain electrode
109
, the semiconductor layer
108
and the source electrode
110
. The gate electrode
105
, the gate insulation film
107
, the semiconductor layer
108
, the drain electrode
109
and the source electrode
110
constitute the TFT.
Furthermore, the liquid crystal driving element formation substrate
101
comprises a black matrix
112
formed on the insulation protection film
111
, for preventing the incidence of light into the TFT and shielding light at a portion which is not associated with display; a color filter
113
formed on the insulation protection film
111
; an insulation protection film
114
made of acryl polymer or the like, which covers the black matrix
112
and the color filter
113
; a contact hole
117
formed in the insulation protection film
111
, the black matrix
112
and the insulation protection film
114
so as to reach the source electrode
110
, a pixel electrode
115
formed of Indium Tin Oxide (ITO) which is formed on the insulation protection film
114
so as to be connected to the source electrode
110
via the contact hole
117
; and a liquid crystal orientation layer
116
formed of polyimide or the like, which is formed on the pixel electrode
115
.
Furthermore, the opposite substrate
102
comprises a transparent insulation substrate
121
formed of glass or the like; a common opposite electrode
122
formed of ITO or the like which is formed on the transparent insulation substrate
121
; and a liquid crystal orientation layer
123
formed of polyimide or the like, which is formed on the opposite electrode
122
.
According to the conventional reflection-type color liquid crystal display apparatus having the above structure, since the black matrix
112
and the color filter
113
are formed on the liquid crystal driving element formation substrate
101
, an overlap margin is not required to be taken wherein a deviation of both the substrates
101
and
102
are considered in the case of assembling the reflection-type color liquid crystal display apparatus by sandwiching the liquid crystal
103
between the liquid crystal driving element formation substrate
101
and the opposite substrate
102
, so that an opening ratio can be enlarged as compared with other structures in which the black matrix
112
and the color filter
113
are formed on the opposite substrate
102
, and brighter display can be provided.
In the reflection-type color liquid crystal display apparatus having the structure described above, light scattering mechanism for scattering light incident from the side of the opposite substrate
102
is required especially when a white color is displayed.
For example, Japanese Patent Application Laid-Open No. hei 11-84415 discloses one example of a reflection-type color liquid crystal display apparatus which provides a white color display as described above.
FIG. 2
is a sectional view showing a structure of another conventional reflection-type color liquid crystal display apparatus. As shown in
FIG. 2
, the another conventional reflection-type color liquid crystal display apparatus is constituted such that a light scattering plate
125
is provided outside of the transparent insulation substrate
121
of the opposite substrate
102
. In other words, the another conventional reflection-type color liquid crystal display apparatus allows the light scattering plate
125
provided outside of a panel of the opposite substrate
102
to function as light scattering mechanism to provide a white color display. Except for the above, the constitution shown in
FIG. 2
is approximately the same as that shown in
FIG. 1
, so that respective portions of
FIG. 2
corresponding to those of the conventional reflection-type color liquid crystal display apparatus shown in
FIG. 1
are denoted with same reference numerals, and an explanation thereof will be omitted here.
However, since the conventional reflection-type color liquid crystal display apparatus is provided with the light scattering mechanism outside of the opposite substrate, the starting point of scattering is set at a point distant from the liquid crystal so that the contrast is lowered.
FIGS. 3 and 4
are sectional views for schematically explaining the reason why the contrast is lowered in the conventional reflection-type color liquid crystal display apparatus. In the case where the scattering plate
125
serving as the light scattering mechanism is provided outside of the opposite substrate
102
, light
131
A,
131
B,
131
C, . . .
131
N incident on a specific incident light region
130
from the outside are irregularly reflected at a boundary portion between the scattering plate
125
and the opposite substrate
102
to be spread in a radial configuration. Then, after part of the irregularly reflected light is incident on the end portion of a color filter
113
, for example, a R(Red) color filter
113
R of an R pixel through a liquid crystal
103
R (Red), it is reflected by the reflection plate
106
to pass through a B(Blue) color filter
113
B of a B(Blue) pixel which is adjacent to the R pixel and a liquid crystal
103
B (Blue) of the B pixel adjacent to the R pixel, and the light is emitted as abnormal light
131
X. Essentially, it is desired that, after the light incident on the color filter
113
R of the R pixel is reflected by the reflection plate
106
, the light passes only through the color filter
113
R of the R pixel and liquid crystal
103
R and it is emitted as normal light
131
Z. As apparent from what has been described above, the specific incident light region
130
causes the generation of color mixing or uncontrollable light.
The fact that light passes through two color filters, like light
134
shown in
FIG. 4
, means that color mixing is generated. On a pixel region in which red color is to be essentially displayed, a mixture of red and blue colors is displayed. Furthermore, the light passes through the liquid crystals of the two pixel regions with the result that uncontrollable light
135
, in which a phase difference
Kikkawa Hironori
Maruyama Muneo
Okamoto Mamoru
Sakamoto Michiaki
Watanabe Takahiko
Duong Thoi V.
Hayes & Soloway P.C.
NEC LCD Technologies Ltd.
Nguyen Dung T.
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