U.S. patent application number 11/686138 was filed with the patent office on 2007-07-05 for color filter substrate and liquid crystal display apparatus having the same.
Invention is credited to Dong-Ho Lee, Yong-Ho Yang.
Application Number | 20070153176 11/686138 |
Document ID | / |
Family ID | 34101807 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070153176 |
Kind Code |
A1 |
Yang; Yong-Ho ; et
al. |
July 5, 2007 |
COLOR FILTER SUBSTRATE AND LIQUID CRYSTAL DISPLAY APPARATUS HAVING
THE SAME
Abstract
A reflection-transmission LCD includes substrates arranged
opposite to each other, a color filter layer formed on at least one
of the substrates, a hole formed in that color filter layer to
substantially minimize differences in color reproducibility between
reflective mode operation and transmission mode operation, a
planarization layer formed on a first of the substrates and
including a first insulating layer formed on the color filter layer
that covers the at least one hole and a second insulating layer
formed on the first insulating layer for substantially planarizing
step differences due to the hole formed in the at least one color
filter layer a common electrode formed on the second insulating
layer, liquid crystal material arranged between the first substrate
and the second substrate, a gate insulating layer formed on the
second substrate, and a third insulating layer formed on the gate
insulating layer.
Inventors: |
Yang; Yong-Ho; (Seoul,
KR) ; Lee; Dong-Ho; (Yongin-si, KR) |
Correspondence
Address: |
F. CHAU & ASSOCIATES, LLC
130 WOODBURY ROAD
WOODBURY
NY
11797
US
|
Family ID: |
34101807 |
Appl. No.: |
11/686138 |
Filed: |
March 14, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10795515 |
Mar 9, 2004 |
7206042 |
|
|
11686138 |
Mar 14, 2007 |
|
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Current U.S.
Class: |
349/114 |
Current CPC
Class: |
G02F 1/133514 20130101;
G02F 1/133555 20130101; G02F 1/133357 20210101 |
Class at
Publication: |
349/114 |
International
Class: |
G02F 1/1335 20060101
G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2003 |
KR |
2003-0053263 |
Claims
1. A reflection-transmission LCD, comprising: a first substrate and
a second substrate arranged opposite the first substrate; a red
(R), green (G) and blue (B) color filter layer formed on the first
substrate; a planarization layer formed on the first substrate; a
hole formed in the color filter layer to substantially minimize
differences in color reproducibility between reflective mode
operation and transmission mode operation; a common electrode
formed on the second insulating layer; liquid crystal material
arranged between the first substrate and the second substrate; a
gate insulating layer formed on the second substrate; and a third
insulating layer formed on the gate insulating layer, wherein the
planarization layer comprises a first insulating layer formed on
the color filter layer that covers the at least one hole, and a
second insulating layer formed on the first insulating layer for
substantially planarizing step differences due to the hole formed
in the color filter layer.
2. The reflection-transmission LCD of claim 1 wherein the third
insulating layer is patterned into reflection portions and
transmission portions.
3. The reflection-transmission LCD of claim 2, further comprising:
a transmission electrode formed on the transmission portions; and a
reflection electrode formed on the reflection portions, wherein the
non-patterned portions comprise a substantially concavo-convex
shape.
4. The reflection-transmission LCD of claim 1, further comprising:
a first hole formed in the red (R) color filter; a second hole
formed in the green (G) color filter; and a third hole formed in
the blue (B) color filter.
5. The reflection-transmission LCD of claim 4 wherein the second
hole is larger than the first hole.
6. The reflection-transmission LCD of claim 4 wherein the third
hole is smaller than the second hole.
7. The reflection-transmission LCD of claim 4 wherein the each of
the red (R), green (G) and blue (B) color filters is divided into a
first area and a second area arranged adjacent to each other where
the first area does not include the hole.
8. The reflection-transmission LCD of claim 7 wherein the second
area of at least one of the red (R), green (G) or blue (B) color
filters includes two holes.
9. The reflection-transmission LCD of claim 7 wherein the first
area is a transmission area and the second area is a reflection
area.
10. A reflection-transmission LCD, comprising; a plurality of
substrates arranged opposite to each other; a color filter layer
formed on at least one of the plurality of substrates; a hole
formed in the at least one color filter layer to substantially
minimize differences in color reproducibility between reflective
mode operation and transmission mode operation; a planarization
layer formed on a first of the plurality of substrates and
comprising a first insulating layer formed on the color filter
layer that covers the at least one hole and a second insulating
layer formed on the first insulating layer for substantially
planarizing step differences due to the hole formed in the at least
one color filter layer; a common electrode formed on the second
insulating layer; liquid crystal material arranged between the
first substrate and the second substrate; a gate insulating layer
formed on the second substrate; and a third insulating layer formed
on the gate insulating layer.
11. The reflection-transmission LCD claim 10 wherein the third
insulating layer is patterned into reflection portions and
transmission portions.
12. The reflection-transmission LCD of claim 11, further
comprising: a transmission electrode formed on the transmission
portions; and a reflection electrode formed on the reflection
portions, wherein the non-patterned portions comprise a
substantially concavo-convex shape.
13. The reflection-transmission LOU of claim 10, further
comprising: a red (R), a green (C), and a blue (B) color filter
formed in the color filter layer; a first hole formed in the red
(R) color filter; a second hole formed in the green (G) color
filter; and a third hole formed in the blue (B) color filter.
14. The reflection-transmission LCD of claim 13 wherein the second
hole is larger than at least one of the first hole or the third
hole.
15. The reflection-transmission LCD of claim 13 wherein the each of
the red (R), green (G) and blue (B) color fitters is divided into a
first area and a second area arranged adjacent to each other
wherein each of the first areas does not have a hole and at least
one of the second areas has two holes.
16. The reflection-transmission LED of claim 15 wherein the first
area is a transmission area and the second area is a reflection
area.
17. The reflection-transmission LCD of claim 10 wherein the
planarization layer is formed over the color filter layer and
extends into at least one hole formed in the color filter
layer.
18. The reflection-transmission LCD of claim 17 wherein the
planarization layer is disposed for leveling a thinner portion of
color filter layer in a reflection area with a thicker portion of
color filter layer in a transmission area.
19. The reflection-transmission LCD of claim 13 wherein two holes
are formed in a red (R) portion of the color filter layer, two
holes are formed in a green (G) portion of the color filter layer,
and one hole is formed in a blue (B) portion of the color fitter
layer.
20. The reflection-transmission LCD of claim 13 wherein two holes
are formed in a red (R) portion of the color fitter layer, two
holes are formed in a green (G) portion of the color filter layer,
and one hole is formed in a blue (B) portion of the color filter
layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional application of co-pending U.S.
application Ser. No. 10/795,515, filed on Mar. 9, 2004, the
disclosure of which is incorporated by reference herein in its
entirety, and which, in turn, claims foreign priority under 35
U.S.C. .sctn. 119 to Korean Patent Application No. 2003-53263,
filed on Jul. 31, 2003, which is hereby incorporated by reference
for all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present disclosure relates to a color filter substrate
and a liquid crystal display (LCD) apparatus having the same, and
more particularly to a color filter substrate capable of improving
display properties.
[0004] 2. Description of the Related Art
[0005] A reflection-transmission type liquid crystal display (LCD)
apparatus is capable of displaying an image in a reflection mode or
in a transmission mode. For example, the image may be displayed in
reflection mode when external light is sufficient to display the
image and the image may be displayed in transmission mode when the
external light is insufficient to display the image, for example,
using generated internal light in the display of the image.
[0006] The reflection-transmission type LCD apparatus, generally,
includes an LCD panel having an array substrate, a color filter
substrate facing the array substrate, and liquid crystal material
interposed between the array substrate and color filter
substrate.
[0007] The array substrate includes a transmission electrode and a
reflection electrode. The transmission electrode includes a
reflection area on which the reflection electrode is formed and a
transmission area on which the reflection electrode is not formed.
The color filter substrate includes a color filter having red,
green, and blue (RGB) color pixels and a common electrode coupled
to the array substrate.
[0008] When the reflection-transmission type LCD apparatus operates
in the reflection mode external light goes through a first pathway
sequentially passing through the color filter, common electrode,
liquid crystal, reflection electrode, liquid crystal, common
electrode, and color filter. When the reflection-transmission type
LCD apparatus operates in the transmission mode, the internal light
goes through a second pathway sequentially passing through the
pixel electrode liquid crystal, common electrode, and color
filter.
[0009] Color reproducibility of the displayed image in the
reflection mode may be different from the color reproducibility of
the displayed image in the transmission mode. This is due to
external light in the reflection mode passing through the color
filter twice and internal light in the transmission mode passes
through the color filter only once. Also, different colorants may
render each of the color pixels have different color visibility and
brightness.
[0010] The difference of color visibility and color reproducibility
between the reflection mode and the transmission mode deteriorate
the display quality of the reflection-transmission type.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present disclosure is directed towards a
color filter substrate and liquid crystal display apparatus having
the same that substantially obviates one or more of the problems
due to limitations and disadvantages of the related art.
[0012] The present disclosure enables reflection-transmission LCD
apparatus to show improved display qualities. The present
disclosure also substantially minimizes differences in color
visibility, brightness, and/or reproducibility between reflection
mode and transmission mode.
[0013] Additional aspects of the disclosure will be set forth in
the description which follows, and in part will be apparent from
the description, or may be learned by practice of the disclosure.
The objectives and other advantages of the disclosure will be
realized and attained by the structure particularly pointed out in
the written description and claims hereof as well as the appended
drawings.
[0014] The present disclosure discloses a reflection-transmission
LCD that reduces differences in color reproducibility between
reflective mode operation and transmission mode operation, which
comprises at least one element formed in a color filter layer to
substantially minimize differences in the color reproducibility
between the reflective mode operation and the transmission mode
operation of the reflection-transmission LCD.
[0015] The present disclosure also discloses a
reflection-transmission LCD, comprising a first substrate and a
second substrate arranged opposite the first substrate. A red (R),
green (G), and blue (B) color filter layer is formed on the first
substrate. A planarization layer is formed on the first substrate
and at least one hole is formed in the color filter layer to
substantially minimize differences in color reproducibility between
reflective mode operation and transmission mode operation.
[0016] The present disclosure discloses another embodiment of a
reflection-transmission LCD comprising a first substrate and a
second substrate arranged opposite the first substrate. A red (R),
green (G), and blue (B) color filter layer is formed on the first
substrate, wherein at least one hole is formed in the color filter
layer to substantially improve display quality of reflective mode
operation and transmission mode operation. The
reflection-transmission LCD comprises a planarization layer formed
on the first substrate, wherein the planarization layer comprises a
first insulating layer formed on the color filter layer to cover
the at least one hole formed in the color filter layer and a
transmission region and a reflection region, wherein the reflection
region has a smaller cell gap than the transmission region.
[0017] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are included to provide a
further understanding of the invention and constitute a part of
this specification, illustrate embodiments of the invention and
together with the description serve to explain the principles of
the invention.
[0019] FIG. 1 shows a cross-sectional view of a color filter
substrate according to an embodiment of the present invention;
[0020] FIG. 2 shows a plan view of a color filter of FIG. 1;
[0021] FIG. 3 shows a plan view of a color filter according to
another exemplary embodiment of the present invention;
[0022] FIG. 4 shows a cross-sectional view of a color filter
substrate according to another embodiment of the present
invention;
[0023] FIGS. 5A, 5B and 5C show views illustrating methods of
fabricating the color filter substrate of FIG. 4;
[0024] FIG. 6 shows a cross-sectional view of a color filter
substrate according to another embodiment of the present
invention;
[0025] FIG. 7 shows a cross-sectional view of a color filter
substrate according to another embodiment of the present invention;
and
[0026] FIG. 8 shows a cross-sectional view of a
reflection-transmission type LCD apparatus having the color filter
substrate shown in FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] Reference will now be made in detail to embodiments of the
present invention, examples of which are illustrated in the
accompanying drawings.
[0028] In FIGS. 1, 2 and 3, the color filter substrate 100 can
reduce differences in color reproducibility and color visibility
between the first area A1 and the second area A2 by forming holes
at the R, G, and B color pixels.
[0029] Additionally, the differences in color reproducibility and
color visibility between the first area A1 and the second area A2
may be reduced by adjusting the respective thickness of the R, G,
and B color pixels.
[0030] More particularly, the R, G, and B color pixels
corresponding to the first area A1 is thicker than the R, G and B
color pixels of the second area A2. In this embodiment, the B color
pixel is thicker than the R color pixel and the G color pixel is
thinner than the R color pixel. This reduces the differences of the
color reproducibility and visibility between the R, G, and B color
pixels.
[0031] FIG. 1 shows a cross-sectional view of a color filter
substrate according to an embodiment of the present invention. FIG.
2 shows a plan view of a color filter of FIG. 1.
[0032] Referring to FIG. 1, a color filter substrate 100 includes a
substrate 100, a color filter 120 formed on the substrate 110, a
planarization layer 130 formed on the color filter 120, and a
common electrode 140 formed on the planarization layer 130. The
color filter substrate 100 is divided into a first area A1 and a
second area A2 adjacent to the first area A1.
[0033] A first light passing through the first area A1 sequentially
goes through the common electrode 140, color filter 120 and
substrate 110. A second light passes through the second area A2
sequentially goes through the substrate 110, color filter 120,
common electrode 140, color filter 120 and substrate 110. The first
light of the first area A1 passes through the color filter 120 only
once. The second light of the second area A2 passes through the
color filter 120 twice.
[0034] The color filter 120 includes a red color pixel (R color
pixel) a green color pixel (G color pixel), and a blue color pixel
(B color pixel).
[0035] A first hole H1 is formed at the second area A2
corresponding to the R color pixel so as to partially expose the
substrate 110. A second hole H2 bigger than the first hole H1 is
formed at the second area A2 corresponding to the G color pixel and
also partially exposes the substrate 110. Additionally, the G color
pixel is smaller than the R color pixel. A third hole H3 is formed
at the second area A2 corresponding to the B color pixel and
smaller than the first hole H1 and partially exposes the substrate
110. The B color pixel is bigger than the G color pixel and the R
color pixel.
[0036] The R, G, and B color pixels of the first area A1 are
entirely covered with respective color filter layer. Out of the R,
G, and B color pixels of the second area A2 respective color filter
layers are partially removed as the first, second and third holes
H1 H2 and H3 are formed. This reduces differences in color
reproducibility between the RGB color pixels formed on the first
area A1 and the RGB color pixels formed on the second area A2.
[0037] In general, the R, G, and B color pixels have different
color visibility and brightness. Among the R, G, and B color
pixels, the color visibility and brightness of the B color pixel
has a wavelength close to a visible ray. The B color is inferior to
that of the R color pixel having a wavelength close to an infrared
ray. The color visibility and brightness of the G color pixel has a
wavelength close to an ultraviolet ray and is superior to the R
color pixel having the wavelength close to the infrared ray.
TABLE-US-00001 TABLE 1 R R R G G G B B R W W H1 x y H2 x y H3 x y x
y A2 0% 0.591 0.357 0% 0.289 0.562 0% 0.140 0.169 0.278 0.352 A2
13% 0.51 0.325 21% 0.3 0.465 6% 0.153 0.18 0.31 0.35 A1 0% 0.516
0.336 0% 0.324 0.472 0% 0.149 0.161 0.304 0.335
[0038] As shown in Table 1, the R, G and B color pixels have x-y
color coordinates different from each other at the first area A1
and the second area A2 when the first hole H1, the second hole H2
and the third hole H3 are not formed in the R, G, and B color
pixels of the second area A2.
[0039] In this embodiment in order to reduce the difference of the
color visibility and brightness of the R, C, and B color pixels,
the first hole H1, the second hole H2, and the third hole H3 of
different sizes are respectively formed at each color pixels of R,
G and B. The first hole H1 is about 13% in size of entire R color
pixel. The second hole H2 is about 21% in size of an entire G color
pixel. The third hole H3 is about 6% in size of an entire B color
pixel.
[0040] The variation of the color coordinates of the G color pixel
depending on the size is smaller than those of the R color pixel
and the B color pixel, because the second hole H2 is bigger than
the first hole H1 and the third hole H3.
[0041] The difference between the color visibility and brightness
of the R, G, and B color pixels is reduced as the second hole H2 is
bigger than the first hole H1 and the third hole H3 is smaller than
the first hole H1. It is also because the G color pixel is smaller
than the R color pixel and the B color pixel is greater than the R
color pixel. The color visibility of the first area A1 is
substantially equal to the second area A2 as the white color
coordinate (0.304, 0.335) of the first area A1 is substantially
equal to the white color coordinate (0.310, 0.350) of the second
area A2.
[0042] Referring to FIG. 2, showing two first holes H1 formed at
the R color pixel. Two second holes H2 are bigger than the first
hole H1 are formed at the G color pixel. A third hole H3 smaller
than the first hole H1 is formed at the B color pixel. Accordingly,
each of the R, G, and B color pixels is different in size.
[0043] Even though the number of first holes H1 is equal to a
number of the second holes H2, overall size of the C color pixel is
smaller than the R color pixel because the first hole H1 is smaller
than the second hole H2.
[0044] In FIGS. 1 and 2, the R, G, and B color pixels are different
in size from each other. As another embodiment of the present
invention, only one of the R, G, and B color pixels may be
different in size from the other two color pixels. That is, the R
color pixel may have substantially the same size as the G color
pixel and the B color pixel may be smaller than the R color pixel.
Optionally, the R color pixel may have substantially the same size
as the B color pixels. The G color pixel may be bigger than the R
color pixel.
[0045] The color filter substrate 100 further includes the
planarization layer 130 for planarizing a step difference between
the substrate 110 exposed through the first, second, and third
holes H1, H2 and H3, respectively, and the color filter 120
adjacent to the first, second, and third holes H1, H2 and H3,
respectively.
[0046] The planarization layer 130 includes a first insulating
layer 131 and a second insulating layer 132. The first insulating
layer 131 is formed on the substrate 110. The second insulating
layer 132 is formed on the first insulating layer 131.
[0047] The step difference between the color filter 120 and
substrate 110 is planarized by the first insulating layer 131 and
then substantially and completely planarized by the second
insulating layer 132 formed on the first insulating layer 131. In
this embodiment, the first insulating layer 131 and second
insulating layer 132 comprise a photosensitive organic insulating
layer, for example, acrylic resin, or the like.
[0048] Also, the first insulating layer 131 may comprise an
inorganic insulating layer, for example, silicon nitride (SiNx),
silicon oxide (SiOx), or the like. The second insulating layer 132
may comprise an organic insulating layer.
[0049] The common electrode 140 is formed on the planarization
layer 130. The common electrode 140 comprises a transparent
conductive material, for example, indium tin oxide (ITO), indium
zinc oxide (IZO), or the like.
[0050] FIG. 3 shows a plan view of a color filter according to
another embodiment of the present invention.
[0051] Referring to FIG. 3, two first holes H4 are formed at the R
color pixel, three second holes H5 are formed at the G color pixel,
and a third hole H6 is formed at the B color pixel. The second hole
H5 and the third hole H6 have substantially the same size as the
first hole H4.
[0052] The R, G, and B color pixels of the second area A2 are
different in sizes because the R, G, and B color pixels have a
different number of holes from each other even though the first,
second, and third holes H4, H5, and H6, respectively, have
substantially the same size. In this embodiment, the G color pixel
is smaller than the R color pixel and the B color pixel is bigger
than the R color pixel.
[0053] FIG. 4 shows a cross-sectional view of a color filter
substrate according to another embodiment of the present invention.
In FIG. 4, the same reference numerals denote the same elements in
FIG. 1 and the detailed descriptions of the same elements will not
be repeated.
[0054] Referring to FIG. 4, a color filter substrate 100 includes a
substrate 110, a color filter 120 formed on the substrate 110, a
planarization layer formed on substrate 110 to cover the color
filter 120, and a common electrode 140 formed on the planarization
layer 150. The color filter substrate 100 includes a first area A1
and a second area A arranged adjacent to the first area A1.
[0055] The color filter 120 includes R, G, and B color pixels. A
first hole H1 is formed at the second area A2 of the R color pixel
and partially exposes the substrate 110. A second hole H2 bigger
than the first hole H1 is formed at the second area A2 of the G
color pixel and partially exposes the substrate 110. Additionally,
the second hole renders the G color pixel smaller than the R color
pixel in effective area. A third hole H3 smaller than the first
hole H1 is formed at the second area A2 of the B color pixels and
partially exposes the substrate 110. The third hole H3 renders the
B color pixel bigger than the G and R color pixels.
[0056] The color filter substrate 100 further includes a
planarization layer 150 for reducing a step difference between the
substrate 110 and the color filter 120.
[0057] The planarization layer 150 comprises a first insulating
layer 151 and a second insulating layer 152. The first insulating
layer 151 is formed on the substrate 110 through areas exposed
through the first, second, and third holes H1, H2 and H3,
respectively. The second insulating layer 152 is formed on the
first insulating layer 131 and on the color filter 120.
[0058] The step difference between the color filter 120 and
substrate 110 is planarized with the first insulating layer 151.
Additionally, the step difference is substantially and completely
planarized with a second insulating layer 152 formed on the first
insulating layer 151 and color filter 120. In this embodiment, the
first insulating layer 151 and second insulating layer 152 comprise
an organic insulating layer.
[0059] The common electrode 140 formed on the planarization layer
150 comprises a transparent conductive material, for example,
indium tin oxide (ITO), indium zinc oxide (IZO), or the like.
[0060] FIGS. 5A, 5B and 5C show views of a method of fabricating
the color filter substrate of FIG. 4.
[0061] Referring to FIG. 5A, the color filter 120 has R, G, and B
color pixels formed on the substrate 110. The first, second, and
third holes H1, H2 and H3, respectively, are formed at the R, G,
and B color pixels, respectively, and these holes partially expose
the substrate 110. More particularly, the R, G, and B color pixels
corresponding to the second area A2 are partially removed in order
to partially expose the substrate 110.
[0062] Referring to FIG. 5B, an organic insulating layer 161 is
formed on the color filter 120 and on the substrate 110 that is
exposed through the first, second, and third holes H1, H2 and H3,
respectively. The organic insulating layer 161 has non-uniform
surface due to the step difference between the substrate 110 and
color filter 120.
[0063] Referring to FIG. 5C, a mask 162 is formed on the organic
insulating layer 161 corresponding to the first, second, and third
holes H1, H2, and H3. The organic insulating layer 161 may be
successively exposed and developed. That is, the first insulating
layer 151 is formed on the substrate 110 and may be exposed through
the first, second, and third holes H1, H2 and H3, respectively.
[0064] As shown in FIG. 5C, the first insulating layer 151 is
thicker than the color filter 120. A first step difference ti
between the color filter 120 and first insulating layer 151 is
smaller than a second step difference t2 between the substrate 110
and color filter 120. The step difference between the substrate 110
and color filter 120 may be reduced as shown in FIG. 4 when the
second insulating layer 152 is formed on the color filter 120 and
first insulating layer 151.
[0065] FIG. 6 shows a cross-sectional view of a color filter
substrate according to another embodiment of the present invention.
In FIG. 6, a color filter substrate 100 includes a substrate 110 a
color filter 120 formed on the substrate 110, a planarization layer
170, and a common electrode 140 formed on the planarization layer
170. The color filter substrate 100 includes a first area A1 and a
second area A2 arranged adjacent to the first area A1.
[0066] The color filter 120 includes R, G, and B color pixels. A
first hole H1 is formed at the second area AS of the R color pixel
and partially exposes the substrate 110. A second hole H2 bigger
than the first hole H1 is formed at the second area A2 of the G
color pixel and partially exposes the substrate 110. A third hole
H3 smaller than the first hole H1 is formed at the second area A2
of the B color pixel and partially exposes the substrate 110.
[0067] The planarization layer 170 includes a first insulating
layer 171 and a second insulating layer 172. The first insulating
layer 171 is formed on the substrate 110 through the first, second,
and third holes H1, H2, and H3, respectively. The second insulating
layer 172 is formed on the first insulating layer 171 and color
filter 120.
[0068] The step difference between the color filter 120 and
substrate 110 is planarized with a first insulating layer 171.
Additionally, the step difference is substantially and completely
planarized with a second insulating layer 172 formed on the first
insulating layer 171 and on the color filter 120.
[0069] In this embodiment, the first insulating layer 171 comprises
an inorganic insulating layer. For example, the inorganic
insulating layer may be silicon nitride (SiNx), silicon oxide
(SiOx), or the like. The second insulating layer 172 comprises an
organic insulating layer. The first insulating layer 171 is thinner
than the color filter 120, additionally, the step difference t3
between the color filter 120 and first insulating layer 171 is
smaller than the step difference t1 between the substrate 110 and
color filter 120.
[0070] The second insulating layer 172 is formed on the first
insulating layer 171 and color filter 120, thereby planarizing the
step difference t3.
[0071] The common electrode 140 may include a transparent
conductive electrode formed on the planarization layer 170. For
example, the common electrode may be indium tin oxide (ITO), indium
zinc oxide (IZO) and the like.
[0072] FIG. 7 shows a cross sectional view of a color filter
substrate according to another embodiment of the present
invention.
[0073] Referring to FIG. 7, a color filter substrate 100 includes a
substrate 110, a color filter 120 formed on the substrate 110, a
planarization layer 180, and a common electrode 140. The color
filter substrate 100 has a first area A1 and a second area A2
arranged adjacent to the first area A1.
[0074] The color filter 120 includes R, G, and B color pixels. A
first hole H1 is formed at the second area A2 of the R color pixel
and partially exposes the substrate 110. A second hole H2 bigger
than the first hole H1 is formed at the second area A2 of the G
color pixel and partially exposes the substrate 110. A third hole
H3 is formed at the second area A2 of the B color pixel and is
smaller than the first hole H1 of the B color pixel and partially
exposes the substrate 110.
[0075] The planarization layer 180 is formed on the substrate 110
through the first, second, and third holes H1, H2, and H3,
respectively. The planarization layer 180 comprises an organic
insulating layer and is thicker than the color filter 120. Although
not shown in FIG. 7, the planarization layer 180 may include an
inorganic insulating layer, so that the planarization layer 180 may
be thinner than the color filter 120.
[0076] In this embodiment, a step difference between the color
filter 120 and planarization layer 180 is smaller than a step
difference between the substrate 110 and color filter 120.
[0077] In FIG. 7, the planarization layer 180 is thicker than the
color filter 120. However, the planarization layer 180 may have
substantially the same thickness as the color filter 120.
[0078] In FIGS. 1, 2, 3, 4, 5, 6 and 7, the planarization layer may
comprise a plurality of layers. For example, the planarization
layer may be a single layer, a double-layer, or a triple-layer.
Also, the color filter substrate having the first, second, and
third holes H1, H2, and H3, respectively, are formed at the R, G,
and B color pixels, respectively described in above drawings may
have one pixel between the R, G, and B color pixels.
[0079] FIG. 8 shows a cross-sectional view of LCD apparatus having
the color filter substrate of FIG. 1.
[0080] Referring to FIG. 8, a reflection-transmission type LCD
apparatus 400 includes an array substrate 200, a color filter
substrate 100 combined with the array substrate 200, and a liquid
crystal 300 interposed between the array substrate 200 and color
filter substrate 100.
[0081] The array substrate 200 includes a first substrate 210, a
gate insulating layer 220 formed on the first substrate 210, a
third insulating layer 230 a transmission electrode 240, and a
reflection electrode 250. The array substrate 200 is divided into a
reflection area RA and a transmission area TA. Although not shown
in FIG. 8, a plurality of TFTs is formed on the first substrate
210. The third insulating layer 230 includes a photosensitive
organic insulating layer, for example, an acrylic resin, or the
like.
[0082] The third insulating layer 230 covers the plurality of TFTs.
The transmission area TA removes a corresponding area of the third
insulating layer 230 and exposes the first substrate 210. The third
insulating layer 230 has a substantially concavo-convex shape 233
on an upper surface. The concavo-convex shape 233 includes a convex
portion 233a and a concave portion 233b.
[0083] The transmission electrode 240 may be a transparent
conductive electrode. For example, the transparent conductive
electrode may comprise indium tin oxide (ITO), indium zinc oxide
(IZO), or the like. The transmission electrode is uniformly formed
on the third insulating layer 230 and on the first substrate 210
where the third insulating layer 230 is removed, The reflection
electrode 250 has a transmission window 251 partially exposing the
transmission electrode 240. The reflection electrode 250 is
uniformly formed on the transmission electrode 240. The
transmission window 251 is formed at a position substantially
corresponding to the transmission area TA.
[0084] A cell gap at the reflection area RA is different from a
cell gap at the transmission area TA. More particularly, the
distance between the color filter substrate 100 and array substrate
200 at the transmission area TA is approximately twice the distance
between the color filter substrate 100 and array substrate 200 at
the reflection area RA.
[0085] In FIG. 8, the cell gap at the reflection area RA is the
distance between the common electrode 140 of the color filter
substrate 100 and reflection electrode 250 of the array substrate
200. The cell gap at the transmission area TA is the distance
between the common electrode 140 and transmission electrode
240.
[0086] The reflection electrode 250 is formed of a conductive
metal. The reflective electrode 250 may be formed of a single layer
having aluminum-neodymium (AINd) or a double-layer having
aluminum-neodymium (AINd) and molybdenum-tungsten (Mo W).
[0087] Although not shown in FIG. 8, a contact hole (not shown) may
be formed at the third insulating layer 230 to expose a drain
electrode of the TFT (not shown). In case of forming the contact
hole at the third insulating layer 230 the transmission electrode
240 and reflection electrode 250 are electrically connected to the
drain electrode of the TFT through the contact hole. For example,
by connecting the drain electrode to the reflection electrode
and/or transmission electrode. Additionally, an additional TFT may
be used in order to drive the reflection electrode and transmission
electrode separately. Accordingly, a drain electrode of the first
TFT may be connected to the reflection and a drain electrode of the
second TFT may be connected to the reflection electrode.
[0088] The reflection electrode 250 formed at the reflection area
RA reflects external light L1 coming through the color filter
substrate 100 and controls the light L1 thereby displaying an
image. Additionally, an internal light L2 is emitted from a light
source (not shown) disposed at a rear portion of the array
substrate 200 and through the transmission area TA. The internal
light L2 passes through the transmission window 251 and is
controlled to exit the color filter substrate 100 thereby
displaying image.
[0089] The color filter substrate 100 includes the color filter
120, planarization layer 130, and common electrode 140. These are
successively formed on the second substrate 110. The color filter
120 includes the R, G, and B color pixels having first, second, and
third holes H1, H2 and H3, respectively. Those holes are formed on
the R, G and B color pixels in the reflection area RA and partially
exposing the second substrate 110.
[0090] The first, second, and third holes H1, H2, and H3,
respectively, are formed by partially removing the color filter 120
in the reflection area RA. Thus, external light L1 input through
the reflection area RA may partially exit without passing through
the color filter 120, reducing the difference of the color
reproducibility between the reflection area RA and transmission
area TA.
[0091] The first hole H1 is bigger than the third hole H3. The
second hole H2 is bigger than the first hole H1. Accordingly, in
effective area, the G color pixel is smaller than the R color pixel
and the R color pixel is smaller than the B color pixel. This
reduces the difference of the color visibility between the R, G,
and B color pixels.
[0092] Table 2 represents the white color coordinate of the color
coordinate in accordance with the cell gap between the color filter
substrate 100 and array substrate 200. TABLE-US-00002 TABLE 2
Reflection mode Transmission Mode Cell gap White-x White-y Cell gap
White-x White-y 1.6 0.300 0.323 3.3 0.300 0.327 1.9 0.322 0.356 3.6
0.312 0.342
[0093] As shown in Table 2, when the cell gap of 1.6 changes to a
cell gap of 1.9 in the reflection mode the x and y coordinates of
the white color are increased by about 0.022 and about 0.032
respectively. In the transmission mode when the cell gap of 3.3 is
changed to a cell gap 3.6 the x and y coordinated of the white
color increased by about 0.012 and about 0.015, respectively. The
white color coordinate of the reflection mode is more sensitive to
the cell gap change than the white color coordinate of the
transmission mode even though variations of the cell gaps are the
same. Thus, the planarization layer 130 has the double-layer
structure so as to planarize the step difference between the second
substrate 110 and color filter 120 at the reflection area RA.
[0094] The planarization layer 130 includes a first insulating
layer 131 formed on the second substrate 110 through the holes H1,
H2 and H3, and on the color filter 120. The second insulating layer
132 is formed on the first insulating layer 131. The planarization
layer 130 may planarize the step difference between the second
substrate 110 exposed through the holes H1, H2, and H3, and the
color fitter 120 adjacent to each of the holes H1, H2 and H3.
[0095] Thus, the reflection-transmission type LCD apparatus 400 may
have a substantially uniform cell gap at the reflection area RA.
Although the convex and concave portions 233a and 233b are formed
at the array substrate 200 corresponding to the reflection area RA,
the convex and concave portions 233a and 233b have a small size
without affecting the cell gap at the reflection area RA.
Accordingly, the cell gap at the reflection area RA may be
substantially uniform.
[0096] The color filter substrate and the reflection-transmission
type LCD apparatus include color pixels of different colors. Each
of the color pixels has a hole and at least two color pixels have a
different size of effective area.
[0097] Thus, the difference of color reproducibility between the
transmission area and the reflection area and the difference of
color visibility between the color pixels may be reduced, thereby
improving display properties of the LCD apparatus. Also, the
planarization layer may planarize the step difference between the
substrate exposed through the hole and the color filter.
Accordingly, the reflection-transmission type LCD apparatus may
have the cell gap substantiality uniform.
[0098] It will be apparent to those of ordinary skill in the
pertinent art that various modifications and variations may be made
in the present invention without departing from the spirit or scope
of the disclosure as set forth herein. Thus it is intended that the
present invention cover all such modifications and variations
provided that they come within the scope of the appended claims or
their equivalents.
* * * * *