U.S. patent application number 16/240417 was filed with the patent office on 2019-05-23 for liquid crystal display including nanocapsule layer.
The applicant listed for this patent is LG Display Co., Ltd.. Invention is credited to Min-Geun Choi, Kyung-Su Ha, Jung-Im Hwang, Ji-Na Jeon, Kyeong-Jin Kim.
Application Number | 20190155074 16/240417 |
Document ID | / |
Family ID | 52775366 |
Filed Date | 2019-05-23 |
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United States Patent
Application |
20190155074 |
Kind Code |
A1 |
Kim; Kyeong-Jin ; et
al. |
May 23, 2019 |
LIQUID CRYSTAL DISPLAY INCLUDING NANOCAPSULE LAYER
Abstract
Disclosed is a liquid crystal display device that may include a
first substrate; a first electrode on the first substrate, the
first electrode including a plurality of first inclined planes; a
nanocapsule liquid crystal layer on the first electrode, the
nanocapsule liquid crystal layer including a plurality of
nano-sized capsules dispersed in a buffer layer, each of the
plurality of nano-sized capsules including nematic liquid crystal
molecules having a negative dielectric constant anisotropy; and a
second electrode on the nanocapsule liquid crystal layer, the
second electrode including a plurality of second inclined planes
facing the plurality of first inclined planes, wherein the
nanocapsule liquid crystal layer is substantially, optically
isotropic in a normal state, and is optically anisotropic when a
voltage is applied to the first and second electrodes.
Inventors: |
Kim; Kyeong-Jin; (Paju-si,
KR) ; Hwang; Jung-Im; (Paju-si, KR) ; Jeon;
Ji-Na; (Paju-si, KR) ; Ha; Kyung-Su; (Paju-si,
KR) ; Choi; Min-Geun; (Paju-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Display Co., Ltd. |
Seoul |
|
KR |
|
|
Family ID: |
52775366 |
Appl. No.: |
16/240417 |
Filed: |
January 4, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15645651 |
Jul 10, 2017 |
10222644 |
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16240417 |
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15359839 |
Nov 23, 2016 |
9759943 |
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15645651 |
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14518327 |
Oct 20, 2014 |
9535279 |
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15359839 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 2001/133541
20130101; G02F 1/133707 20130101; G02F 1/13338 20130101; G02F
1/133603 20130101; G02F 1/133524 20130101; G02F 1/133514 20130101;
G02F 1/133528 20130101; G02F 1/13363 20130101; G02F 2202/36
20130101; G02F 1/1334 20130101; G02F 1/1368 20130101; G02B 6/0056
20130101; G02F 2001/13712 20130101; G02F 1/13718 20130101; G02F
1/134309 20130101; G02F 2001/133531 20130101; G02F 2203/02
20130101; G02F 1/133305 20130101; G02F 1/133553 20130101; G02F
2001/133638 20130101 |
International
Class: |
G02F 1/1334 20060101
G02F001/1334; G02F 1/13363 20060101 G02F001/13363; G02F 1/1368
20060101 G02F001/1368; G02F 1/1335 20060101 G02F001/1335; G02F
1/1333 20060101 G02F001/1333; G02F 1/137 20060101 G02F001/137; G02F
1/1343 20060101 G02F001/1343; G02F 1/1337 20060101
G02F001/1337 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2013 |
KR |
10-2013-0126534 |
Dec 6, 2013 |
KR |
10-2013-0151308 |
Dec 10, 2013 |
KR |
10-2013-0152890 |
Claims
1-33. (canceled)
34. A flexible type liquid crystal display device comprising: a
liquid crystal panel that includes a nanocapsule liquid crystal
layer on a substrate which a first electrode and a second electrode
are formed on; a polarizing plate on the liquid crystal panel; and
a backlight unit that is below the liquid crystal panel, and
supplies a predetermined linearly polarized light perpendicular to
a polarizing axis of the polarizing plate, wherein the nanocapsule
liquid crystal layer has an optical anisotropy according to a
voltage difference between voltages applied to the first and second
electrodes, and has an optical isotropy when no voltages are
applied to the first and second electrodes.
35. The device of claim 34, wherein the backlight unit includes: a
light guide plate; a light source arranged along a light incidence
surface of the light guide plate; and a reflective polarizing film
between the light source and the light incidence surface of the
light guide plate.
36. The device of claim 34, wherein the backlight unit includes: a
light guide plate; and non-polar or semi-polar LEDs that are
arranged along a light incidence surface of the light guide plate
and emit polarized light to the light guide plate.
37. The device of claim 34, wherein the backlight unit includes: a
light guide plate including a wire grid lattice; and a light source
arranged along a light incidence surface of the light guide
plate.
38. The device of claim 34, wherein the backlight unit includes: a
light guide plate; a light source arranged along a light incidence
surface of the light guide plate; and a polarization separation
layer on the light guide plate.
39. The device of claim 35, wherein a reflection sheet is below the
light guide plate, and at least one optical sheet is on the light
guide plate.
40. The device of claim 35, wherein the light guide plate includes
a plurality of optical fibers that are parallel with each other to
form a plate, wherein each optical fiber includes: a core; and a
clad that encloses an outer surface of the core, and that includes
a light guide portion having a refractive index less than a
refractive index of the core, and a light emission portion having a
refractive index equal to or greater than the refractive index of
the core.
41. The device of claim 36, wherein the light guide plate includes
a plurality of optical fibers that are parallel with each other to
form a plate, wherein each optical fiber includes: a core; and a
clad that encloses an outer surface of the core, and that includes
a light guide portion having a refractive index less than a
refractive index of the core, and a light emission portion having a
refractive index equal to or greater than the refractive index of
the core.
42. The device of claim 35, wherein the reflective polarizing film
is formed to have a multi-layered structure that includes a
polarizer embedded in a lamination structure of dielectric thin
films having different refractive indices, or is formed to be a
wire grid type reflective polarizing film that includes fine metal
patterns arranged in parallel along a direction.
43. The device of claim 34, wherein the nanocapsule liquid crystal
layer is located facing the backlight unit, and the polarizing
plate is located at an outer side of the substrate.
44. The device of claim 43, wherein a touch panel is located on the
outer side of the substrate.
45. The device of claim 34, wherein the liquid crystal panel and
the backlight unit are modulized in a lamination process using an
adhesive.
46. The device of claim 34, wherein a diameter of a nano-sized
capsule of the nanocapsule liquid crystal layer is about 1 nm to
about 320 nm.
47. The device of claim 34, wherein a volume of a nano-sized
capsule of the nanocapsule liquid crystal layer is about 25% to
about 65% of a volume of the nanocapsule liquid crystal layer.
48. The device of claim 34, wherein a thickness of the nanocapsule
liquid crystal layer is about 2 um to about 5 um.
49. The device of claim 34, wherein a refractive index different
between a liquid crystal molecule and a nano-sized capsule of the
nanocapsule liquid crystal layer is about .+-.0.1.
Description
[0001] This application claims the benefit of Korean Patent
Application Nos. 10-2013-01126534, 10-2013-0151308 and
10-2013-0152890, filed on Oct. 23, 2013, Dec. 6, 2013 and Dec. 10,
2013, respectively, which are hereby incorporated by reference for
all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a liquid crystal display
device (LCD), and more particularly, to an LCD including a
nanocapsule layer and method for manufacturing the same.
Discussion of the Prior Art
[0003] Recently, facing information society, display field of
displaying electric information signals has been rapidly advanced,
and flat display devices having high performances of thin profile,
lightweight and low power consumption have been developed and used.
Among these flat display devices, liquid crystal display devices
(LCDs) are widely used.
[0004] FIG. 1 is a cross-sectional view illustrating an LCD
according to the prior art.
[0005] Referring to FIG. 1, the LCD includes a liquid crystal panel
10 including an array substrate, a color filter substrate and a
liquid crystal layer 50 between the array substrate and the color
filter substrate, and a backlight unit 60 below the liquid crystal
panel 10. A first substrate 2 referred to as the array substrate
includes a pixel region P, and on an inner surface of the first
substrate 2, a thin film transistor T is in each pixel region P and
connected to a pixel electrode P in each pixel region P.
[0006] On an inner surface of a second substrate 4 referred to as
the color filter substrate, a black matrix 32 is formed in a
lattice shape surrounding the pixel region P to cover a non-display
element such as the thin film transistor T and expose the pixel
electrode 28.
[0007] Red, green and blue color filters 34 are formed in the
lattice shape corresponding to the respective pixel regions P, and
a common electrode 36 is formed on the black matrix 32 and the
color filters 34.
[0008] First and second polarizing plates 20 and 30 are attached
onto outer surfaces of the first and second substrates 2 and 4,
respectively.
[0009] First and second alignment layers 31a and 31b are formed
between both the pixel electrode 28 and the common electrode 36,
and the liquid crystal layer 50. The first and second alignment
layers 31a and 31b are rubbed and align liquid crystal
molecules.
[0010] A seal pattern 70 is formed between and along peripheral
regions of the first and second substrates 2 and 4 and prevents
leakage of the liquid crystal.
[0011] The backlight unit 60 supplies light to the liquid crystal
panel 10. The backlight unit 60 is categorized into a sidelight
type and a direct type.
[0012] The sidelight type backlight unit has a light source on at
least one side of a light guide panel. The direct type backlight
unit has a light source below the liquid crystal panel 10.
[0013] The sidelight type backlight unit has advantages of simple
manufacturing, thin profile, lightweight, and low power
consumption.
[0014] FIG. 2 is a cross-sectional view illustrating the LCD
including the backlight unit according to the prior art.
[0015] Referring to FIG. 2, the backlight unit 60 includes a light
guide plate 23, a light emitting diode (LED) assembly 29 along a
side of the light guide plate 23, a reflector 25 below the light
guide plate 23, and at least one optical sheets 21 on the light
guide plate 23.
[0016] The LED assembly 29 includes a plurality of LEDs 29a, and a
printed circuit board (PCB) 29b on which the LEDs 29a are
mounted.
[0017] Light emitted from the LED assembly 29 enters into the light
guide plate 23, then is refracted toward the liquid crystal panel
10, then is processed into light of high quality and uniform
brightness passing through the optical sheet 21, and then enters
into the liquid crystal panel 10. Accordingly, the liquid crystal
panel 10 displays images.
[0018] A portion of the light emitted from the backlight unit 60 is
absorbed and reflected by the first polarizing plate 20 and thus is
lost, which may be about 50% of all the light emitted from the
backlight unit 60. Further, light is absorbed and reflected while
passing through the first and second substrates 2 and 4 and the
liquid crystal layer (50 of FIG. 1), and thus an additional portion
of the light is lost. As such, the LCD has disadvantage in
brightness compared with other types of flat display displays.
[0019] Moreover, the LCD has slow response speed, and thus display
quality is reduced due to afterimage.
[0020] Moreover, the LCD requires many production processes, and
thus production efficiency is reduced.
[0021] The above LCD using the backlight unit 60 is referred to as
a transmissive type LCD, in which the backlight unit 60 consumes
about two-third or more of a total power of the LCD. To solve this
problem, a reflective type LCD not using a backlight unit is
suggested.
[0022] However, in the reflective type LCD, light leakage is easily
caused by an external force, and thus display quality is reduced.
Moreover, the reflective type LCD also requires many production
processes, and thus production efficiency is reduced.
SUMMARY OF THE INVENTION
[0023] Accordingly, the present invention is directed to a liquid
crystal display device (LCD) including a nanocapsule layer and
method for manufacturing the same that substantially obviates one
or more of the problems due to limitations and disadvantages of the
prior art.
[0024] An advantage of the present invention is to provide an LCD
including a nanocapsule layer that can improve its response speed
and/or production efficiency.
[0025] Additional features and advantages of the invention 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
invention. These and other advantages of the invention will be
realized and attained by the structure particularly pointed out in
the written description and claims hereof as well as the appended
drawings.
[0026] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described herein, a liquid crystal display device may include a
first substrate; a first electrode on the first substrate, the
first electrode including a plurality of first inclined planes; a
nanocapsule liquid crystal layer on the first electrode, the
nanocapsule liquid crystal layer including a plurality of
nano-sized capsules dispersed in a buffer layer, each of the
plurality of nano-sized capsules including nematic liquid crystal
molecules having a negative dielectric constant anisotropy; and a
second electrode on the nanocapsule liquid crystal layer, the
second electrode including a plurality of second inclined planes
facing the plurality of first inclined planes, wherein the
nanocapsule liquid crystal layer is substantially, optically
isotropic in a normal state, and is optically anisotropic when a
voltage is applied to the first and second electrodes.
[0027] In another aspect, a liquid crystal display device may
include a first substrate; a first polarizing plate on an outer
surface of the first substrate; a first electrode on an inner
surface of the first substrate; a nanocapsule liquid crystal layer
that is on the first electrode and includes nano-sized capsules
which are each filled with nematic liquid crystal molecules of
negative dielectric constant anisotropy and are dispersed in a
buffer layer; and a second electrode on the nanocapsule liquid
crystal layer; a phase retardation film that is on the second
electrode and has a phase retardation value of .lamda./4; and a
second polarizing plate on the phase retardation film, wherein the
nanocapsule liquid crystal layer has an optical anisotropy
according to a voltage difference between voltages applied to the
first and second electrodes, and has an optical isotropy when no
voltages are applied to the first and second electrodes.
[0028] In another aspect, a liquid crystal display device may
include a first substrate; a plurality of first electrodes on an
inner surface of the first substrate; a nanocapsule liquid crystal
layer that is on the plurality of first electrodes and includes
nano-sized capsules which are each filled with nematic liquid
crystal molecules of negative dielectric constant anisotropy and
are dispersed in a buffer layer; and a second electrode on the
nanocapsule liquid crystal layer, wherein the nanocapsule liquid
crystal layer has an optical anisotropy according to a voltage
difference between voltages applied to the first and second
electrodes, and has an optical isotropy when no voltages are
applied to the first and second electrodes.
[0029] In another aspect, a reflective type liquid crystal display
device may include a liquid crystal panel that includes a first
electrode, a second electrode, and a nanocapsule liquid crystal
layer between the first and second electrodes; a polarizing plate
that is on a surface of the liquid crystal layer through which an
external light enters; a phase retardation plate between the
polarizing plate and the liquid crystal panel; and a reflection
plate that reflects light passing through the nanocapsule liquid
crystal layer, wherein the nanocapsule liquid crystal layer has an
optical anisotropy according to a voltage difference between
voltages applied to the first and second electrodes, and has an
optical isotropy when no voltages are applied to the first and
second electrodes.
[0030] In another aspect, a flexible type liquid crystal display
device may include a liquid crystal panel that includes a
nanocapsule liquid crystal layer on a substrate which a first
electrode and a second electrode are formed on; a polarizing plate
on the liquid crystal panel; and a backlight unit that is below the
liquid crystal panel, and supplies a predetermined linearly
polarized light perpendicular to a polarizing axis of the
polarizing plate, wherein the nanocapsule liquid crystal layer has
an optical anisotropy according to a voltage difference between
voltages applied to the first and second electrodes, and has an
optical isotropy when no voltages are applied to the first and
second electrodes.
[0031] 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
[0032] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in 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. In the drawings:
[0033] FIG. 1 is a cross-sectional view illustrating an LCD
according to the prior art;
[0034] FIG. 2 is a cross-sectional view illustrating the LCD
including the backlight unit according to the prior art;
[0035] FIG. 3 is a schematic perspective view illustrating an LCD
according to the present invention;
[0036] FIGS. 4A and 4B are views illustrating the prior art LCD and
an LCD according to an embodiment of the present invention,
respectively, to which an external force is applied;
[0037] FIGS. 5A and 5B are schematic views illustrating an LCD
according to a first embodiment of the present invention;
[0038] FIG. 6 is a schematic view illustrating a COT type LCD
according to the first embodiment of the present invention;
[0039] FIG. 7 is a schematic view illustrating a COT type LCD
without a second substrate according to the first embodiment of the
present invention;
[0040] FIGS. 8A and 8B are schematic views illustrating an LCD
according to a second embodiment of the present invention;
[0041] FIG. 9 is a schematic view illustrating a COT type LCD
according to the second embodiment of the present invention;
[0042] FIG. 10 is a schematic view illustrating a COT type LCD
without a second substrate according to the second embodiment of
the present invention;
[0043] FIG. 11A is a schematic view illustrating an LCD according
to a third embodiment of the present invention;
[0044] FIG. 11B is a schematic view illustrating multi-domains of
FIG. 11A.
[0045] FIG. 12A is a schematic view illustrating an LCD according
to a fourth embodiment of the present invention;
[0046] FIG. 12B is a schematic view illustrating multi-domains of
FIG. 12A.
[0047] FIG. 13 is a perspective view illustrating an LCD according
to a fifth embodiment of the present invention;
[0048] FIGS. 14A and 14B are schematic views illustrating an image
display principle of an LCD according to the fifth embodiment of
the present invention;
[0049] FIGS. 15A and 15B are schematic views illustrating variation
of light in the states of FIGS. 14A and 14B, respectively;
[0050] FIGS. 16A and 16B are schematic views illustrating an image
display principle of an LCD according to the sixth embodiment of
the present invention;
[0051] FIGS. 17A and 17B are schematic views illustrating an image
display principle of an LCD according to a seventh embodiment of
the present invention;
[0052] FIGS. 17C and 17D are schematic views illustrating an LCD
according to eighth and ninth embodiments of the present invention,
respectively;
[0053] FIG. 18 is a schematic view illustrating an LCD according to
a tenth embodiment of the present invention;
[0054] FIG. 19A is a schematic view illustrating an LCD according
to an eleventh embodiment of the present invention; and
[0055] FIG. 19B is a schematic perspective view illustrating an
optical fiber of an optical fiber type light guide plate of FIG.
19A.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0056] Reference will now be made in detail to exemplary
embodiments, examples of which are illustrated in the accompanying
drawings. The same reference numbers may be used throughout the
drawings to refer to the same or like parts.
[0057] FIG. 3 is a schematic perspective view illustrating an LCD
according to an embodiment of the present invention.
[0058] Referring to FIG. 3, the LCD 100 includes a liquid crystal
panel 110 that includes a first substrate 112, a second substrate
114, and a nanocapsule liquid crystal layer 200 between the first
and second substrates 112 and 114.
[0059] The first substrate 112 is referred to as a lower substrate
or an array substrate. A plurality of gate lines 116 and a
plurality of data lines 118 cross each other on an inner surface of
the first substrate 112 to define a plurality of pixel regions
P.
[0060] A thin film transistor T is formed near the crossing portion
of the gate and data lines 116 and 118, and is connected to a pixel
electrode 124 in the pixel region P.
[0061] The second substrate 114 is referred to as an upper
substrate or a color filter substrate. A black matrix 132 is on an
inner surface of the second substrate 114, and shields a
non-display element such as the gate line 116, the data line 118,
and the thin film transistor T exposing the pixel electrode 124.
The black matrix 132 has a lattice shape surrounding the pixel
region P.
[0062] Red, green and blue color filters 134 fill openings of the
black matrix 132 corresponding to the respective pixel regions P. A
common electrode 136 covers the black matrix 132 and the color
filters 134.
[0063] Even though not shown in the drawings, the first substrate
112 has an area greater than that of the second substrate 114 so
that a peripheral portion of the first substrate 112 is exposed
outside the second substrate 114. In the exposed portion of the
first substrate 112, data pads 118a connected to the respective
data lines 118, and gate pads (not shown) connected to the
respective gate lines 116 are formed.
[0064] When a gate line 116 is selected and supplied with a turn-on
gate signal i.e., high-level gate signal, the thin film transistor
T connected to the selected gate line 116 is turned on and an image
data signal is transferred to the pixel electrode 124 through the
data line 118. Accordingly, an electric field is induced between
the pixel electrode 124 and the common electrode 136 and controls
liquid crystal molecules 220 of the nanocapsule liquid crystal
layer 200, and thus light transmittance is changed to display
images.
[0065] A first polarizing plate 120 and a second polarizing plate
130 are attached onto outer surfaces of the liquid crystal panel
110. In other words, the first polarizing plate 120 is on an outer
surface of the first substrate 112, and the second polarizing plate
130 is on an outer surface of the second substrate 114. The first
polarizing plate 120 has a first polarizing axis along a first
direction while the second polarizing plate 130 has a second
polarizing axis along a second direction perpendicular to the first
direction.
[0066] A backlight unit 160 is located below the liquid crystal
panel 110 to supply light to the liquid crystal panel 110.
[0067] A sidelight type or direct type backlight unit may be used
as the backlight unit 160.
[0068] A cold cathode fluorescent lamp (CCFL), an external
electrode fluorescent lamp (EEFL), or a light emitting diode (LED)
may be used as a light source of the backlight unit 160.
[0069] The nanocapsule liquid crystal layer 200 includes a
plurality of nanocapsules 230 and a buffer layer 210. The
nanocapsules 230 are dispersed in the buffer layer 210, with each
including a plurality of liquid crystal molecules 220 therein. The
nanocapsule liquid crystal layer 200 changes light transmittance to
display images.
[0070] The nanocapsule liquid crystal layer 200 is an optically
isotropic type liquid crystal layer in a normal state. Accordingly,
when no electric field is applied to the nanocapsule liquid crystal
layer 200 between the pixel electrode 124 and the common electrode
136, the nanocapsule liquid crystal layer 200 is optically
isotropic. However, when an electric field is applied, the
nanocapsule liquid crystal layer 200 has a birefringence property
in a direction perpendicular to the applied electric field.
[0071] Accordingly, when an electric field is applied, the
nanocapsule liquid crystal layer 200 may have an optically uniaxial
property, with light transmittance being dependent upon viewing
angles.
[0072] When an electric field is applied, the liquid crystal
molecules 220 are regularly arranged at about 45 degrees with
respect to the polarizing axis of each of the first and second
polarizing plates 120 and 130.
[0073] In more detail, the liquid crystal molecules 220 are
capsuled by the nanocapsule 230 having a nanosize, and the liquid
crystal molecules 220 are irregularly arranged within the
nanocapsule 230.
[0074] The nanocapsule 230 may have about 5% to about 95% of a
total volume of the nanocapsule liquid crystal layer 200, and
preferably, may have about 25% to about 65% of the total volume of
the nanocapsule liquid crystal layer 200. The buffer layer 210
occupies the rest of the total volume.
[0075] The buffer layer 210 may be made of a transparent or
semi-transparent material and have water-solubility,
fat-solubility, or mixture of water-solubility and fat-solubility.
The buffer layer 210 may be heat cured or UV cured.
[0076] The buffer layer 210 may have an additive to increase
strength and reduce curing time.
[0077] The nanocapsule 230 may have a diameter of about 1 nm to
about 320 nm, and preferable, about 30 nm to about 100 nm.
[0078] Because the nanocapsule 230 has a diameter less than any
wavelengths of visible light, there occurs substantially no optical
change due to refractive index, and optically isotropic property
can be obtained. Further, scattering of visible light can be
minimized.
[0079] Particularly, when the nanocapsule 230 is formed with a
diameter of about 100 nm or less, high contrast ratio can be
obtained.
[0080] The irregularly arranged liquid crystal molecules 220 and
the nanocapsule 230 have different refractive indices, and thus a
light scattering may occur at the interface therebetween.
Accordingly, when light passes through the interface, the light is
scattered and becomes opaque in milk white.
[0081] However, when an electric field is applied to the
nanocapsule liquid crystal layer 200, the liquid crystal molecules
220 filling the nanocapsule 230 are regularly arranged.
[0082] In this state, the refractive index of the liquid crystal
molecules 220 is changed. In order to reduce or minimize a light
scattering at the interface between the nanocapsule 230 and the
liquid crystal molecules 220, the nanocapsule 230 and the regularly
arranged liquid crystal molecules 220 are formed such that they
have refractive indices that are substantially close to each other,
Therefore, the nanocapsule liquid crystal layer 200 can be seen
transparent.
[0083] In this case, it is preferred that a difference between the
refractive index of the nanocapsule 220 and the refractive index of
the liquid crystal molecules 220 is within about .+-.0.1. The
average refractive index (n) of the liquid crystal molecules 220
may be defined as follows: n=[(ne+2*no)/3] (where ne is a
refractive index of a major axis of the liquid crystal molecules
220, and no is a refractive index of a minor axis of the liquid
crystal molecules 220).
[0084] Accordingly, the LCD 100 including the nanocapsule liquid
crystal layer 200 can be used as a display device, with its
transmittance changing according to a variation of the voltage
applied.
[0085] Further, when the electric field is induced between the
first and second substrates 112 and 114, the liquid crystal
molecules 220 are dynamically rotated, and thus response speed can
be fast.
[0086] Further, since the nanocapsule liquid crystal layer 200 does
not have an initial alignment to be optically anisotropic,
alignment of liquid crystal molecules may not be required, and thus
no alignment layer may be needed in the LCD 100, and also,
processes for forming an alignment layer such as rubbing may not be
needed.
[0087] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of, for example, liquid crystal, the
nanocapsule liquid crystal layer 200 may be formed, for example, by
a printing method, coating method, or dispensing method. In case
that the nanocapsules 230 are dispersed in the buffer layer 210
made in a film type, the nanocapsule liquid crystal layer 200 may
be formed, for example, by a lamination method. Accordingly, a
process of forming a gap between the first and second substrates
filled with the liquid crystal layer (50 of FIG. 1) in the prior
art can be eliminated, and a process of forming the seal pattern
(70 of FIG. 1) in the prior art can be eliminated.
[0088] Therefore, production efficiency can be improved.
[0089] Further, by eliminating the process of forming the alignment
layer, in case that the LCD 100 is applied to a touch display
device, curved display device or flexible display device, light
leakage, which occurs when a rubbing axis is off a desired
direction and thus arrangement of liquid crystal molecules goes
awry, can be prevented.
[0090] Therefore, the LCD 100 can be applied to a touch display
device, curved display device, and flexible display device.
[0091] FIGS. 4A and 4B are views illustrating the prior art LCD and
an LCD according to an embodiment of the present invention,
respectively, to which an external force is applied.
[0092] Referring to FIG. 4A, when an external force such as a
user's touch is applied to the prior art LCD, arrangement of the
liquid crystal molecules of the prior art LCD is influenced by the
external force. In other words, arrangement of the liquid crystal
molecules are awry due to the external force, thus optic axis is
off, and thus light leakage 70 is caused.
[0093] However, referring to FIG. 4B, even when an external force
such as a user's touch is applied to the LCD 100, the liquid
crystal molecules 220 are in the nanocapsule 230 which has the size
less than the wavelength of visible light, thus there is no
influence of visible light, and thus light leakage due to the
external force can be reduced or prevented.
[0094] Accordingly, in case that the LCD 100 is applied to a
flexible display device, even when an external force is applied to
the LCD 100, a light leakage caused by such an external force can
be reduced or prevented, because the nanocapsules 230 have a size
less than the wavelength of visible light.
[0095] It is preferable that the liquid crystal molecules 220 are a
negative type liquid crystal molecules with a negative dielectric
constant anisotropy, for example, a negative type TN (twisted
nematic) liquid crystal molecules.
[0096] The negative type liquid crystal molecules 220 are arranged
in a direction perpendicular to an electric field induced between
the pixel electrode 124 and the common electrode 136.
[0097] In other words, the nanocapsule liquid crystal layer 200
uses the nanocapsules 230 having the negative type liquid crystal
molecules 220 therein, and when no electric field is applied, the
nanocapsule liquid crystal layer 200 has an optical isotropy, and
when an electric field is applied, the nanocapsule liquid crystal
layer 200 has an optical anisotropy.
[0098] Various embodiments of the LCD 100 using the nanocapsule
liquid crystal layer 200 are explained as below.
First Embodiment
[0099] FIGS. 5A and 5B are schematic views illustrating an LCD
according to the first embodiment of the present invention.
[0100] Referring to FIGS. 5A and 5B, the LCD of the first
embodiment includes the liquid crystal panel 110 and the backlight
unit 160.
[0101] The liquid crystal panel 110 includes the first and second
substrates 112 and 114 facing each other, the nanocapsule liquid
crystal layer 200, and the first and second polarizing plates 120
and 130 on the outer surfaces of the first and second substrates
112 and 114, respectively.
[0102] The liquid crystal panel 110 may be a vertical alignment
(VA) mode liquid crystal panel. The thin film transistor (T of FIG.
3) and the pixel electrode 124 are formed on the inner surface of
the first substrate 112. The black matrix (132 of FIG. 3), the
color filters 134, and the common electrode 136 are formed on the
inner surface of the second substrate 114. An overcoat layer may be
formed covering the black matrix 132 and the color filters 134.
[0103] A plurality of protrusion patterns 150 are arranged in a
line form below each of the pixel electrode 124 and the common
electrode 136. The protrusion patterns 150 adjoin each other in a
band shape extending along a first direction, for example, a length
direction of the pixel electrode 124 and the common electrode 136.
The protrusion patterns 150 extending along the first direction are
repeatedly arranged along a second direction perpendicular to the
first direction such that hills and valleys are alternated along
the second direction.
[0104] The protrusion pattern 150 is made of a transparent
insulating material, and has a vertex and first and second inclined
planes at both sides of the vertex. The first and second inclined
planes are at a cute angle with respect to the plane of the first
and second substrates 112 and 114. The inclined plane of the
protrusion pattern 150 of the pixel electrode 124 faces and is
parallel with the corresponding inclined plane of the protrusion
pattern of the common electrode 136.
[0105] Because of the protrusion patterns 150 described above, the
pixel electrode 124 and the common electrode 136 each have
substantially the same configuration of the protrusion patterns 150
therebelow.
[0106] In other words, the pixel electrode 124 is formed to have
vertices and first and second inclined planes at both sides of each
vertex, and the common electrode 136 is formed to have vertices and
first and second inclined planes at both sides of each vertex.
[0107] The incline plane of the pixel electrode 124 faces and is
parallel with the corresponding inclined plane of the common
electrode 136 so that intervals between the corresponding planes of
the pixel electrode 124 and the common electrode 136 are
substantially identical overall.
[0108] Because the pixel electrode 124 and the common electrode 136
each have the inclined planes, an electric field between the pixel
electrode 124 and the common electrode 136 is induced
perpendicularly to the inclined planes of the pixel electrode 124
and the common electrode 136.
[0109] Accordingly, the liquid crystal molecules 220 are arranged
perpendicularly to the induced electric field according to a pixel
voltage i.e., a difference voltage between the voltages applied to
the pixel electrode 124 and the common electrode 136. In this
regard, the liquid crystal molecules 220 are arranged at a tilt
angle of about 1 degree to about 5 degrees with respect to the
first substrate 112.
[0110] In other words, the liquid crystal molecules 220 are
arranged perpendicularly to the electric field between the pixel
electrode 124 and the common electrode 136, and a refractive index
in a direction perpendicular to the electric field is
manifested.
[0111] Accordingly, to realize a maximum brightness, the polarizing
axes of the first and second polarizing plates 120 and 130 are
attached to each make a 45 degrees angle with the liquid crystal
molecule 220 perpendicular to the electric field.
[0112] The backlight unit 160 supplies a scattering light close to
a natural light to the liquid crystal panel 110.
[0113] As illustrated in FIG. 5A, when a voltage is off, a
scattering light from the backlight unit 160 enters the first
polarizing plate 120 and a linearly polarized light parallel with
the polarizing axis (i.e., the transmission axis) of the first
polarizing plate 120 passes through and comes out from the first
polarizing plate 120.
[0114] However, in the voltage-off state, the liquid crystal
molecules 220 are arranged randomly, the liquid crystal molecules
220 and the nano capsule 230 have different anisotropies in
refractive index from each other. Accordingly, optically isotropic
property is obtained.
[0115] Accordingly, the linearly polarized light from the first
polarizing plate 120 passes through the nanocapsule liquid crystal
layer 200 as is, and does not pass through the second polarizing
plate 130 having the polarizing axis perpendicular to the
polarizing axis of the first polarizing plate 120. Thus, a black is
displayed.
[0116] As illustrated in FIG. 5B, when voltages are applied to the
pixel electrode 124 and the common electrode 136, the liquid
crystal molecules 220 are arranged perpendicularly to the electric
field, at an angle of about 1 degree to about 5 degrees with
respect to the plane of the first substrate 112.
[0117] Accordingly, the nanocapsule liquid crystal layer 200 has an
optical anisotropy.
[0118] Accordingly, a scattering light from the backlight unit 160
enters through the first polarizing plate 120 so that a linearly
polarized light comes out and other part is absorbed, and then a
linearly polarized light, which is parallel with the liquid crystal
molecules 220, out of the linearly polarized light coming out from
the first polarizing light 120, passes through the liquid crystal
layer 200.
[0119] Then, a linearly polarized light, which is parallel with the
polarizing axis of the second polarizing plate 130, out of the
linearly polarized light passing through the liquid crystal layer
200 passes through the second polarizing plate 130, and thus a
white is displayed.
[0120] As described above, the pixel electrode 124 and the common
electrode 136 are configured to have the inclined planes, and thus
the negative type liquid crystal molecules 220 are arranged at a
tilt angle of about 1 degree to 5 degrees with respect to the first
substrate 112 by the electric field between the pixel and common
electrodes 124 and 136. Accordingly, the negative type liquid
crystal molecules can be arranged more uniformly.
[0121] In other words, in case that the pixel electrode 124 and the
common electrode 136 have the inclined plane, the negative type
liquid crystal molecules 220 randomly arranged collide one another
without directivity in the process that the molecules 220 are
arranged perpendicularly to the electric field induced between the
pixel and common electrodes 124 and 136.
[0122] Because of such a collision among the liquid crystal
molecules 220, the liquid crystal molecules 220 are not arranged in
parallel with one another, and this causes a light leakage.
[0123] Further, this light leakage causes non-uniformity of
brightness and image.
[0124] However, according to the pixel and common electrodes 124
and 136 having the slanted plane in this embodiment, the liquid
crystal molecules 220 can be more easily rotated and uniformly
arranged in the same direction by the electric field perpendicular
to the slanted plane of the pixel and common electrodes 124 and
136.
[0125] Accordingly, the awry arrangement of the liquid crystal
molecules 220 due to the collision can be reduced or prevented, and
thus a light leakage by an awry arrangement can be also reduced or
prevented.
[0126] This can improve the transmittance of the LCD 100.
[0127] Further, since the liquid crystal molecules 220 are arranged
in parallel at a tilt angle of 1 degree to 5 degrees, rotation of
the liquid crystal molecules 220 can be easily made and thus a
response time can be more improved.
[0128] As described above, in the LCD 100 of the first embodiment,
the nanocapsule liquid crystal layer 200 including the nanocapsules
230 that are filled with the negative type liquid crystal molecules
220 and are dispersed in the buffer layer 210 is located between
the first and second substrates 112 and 114, and thus a response
time can be improved compared with that of the prior art.
[0129] Further, since the nanocapsule liquid crystal layer 200 does
not have an optically anisotropic initial arrangement, an alignment
layer may not be needed in the LCD and a rubbing process may also
not be needed.
[0130] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of liquid crystal, the nanocapsule liquid
crystal layer 200 is formed in a printing method, coating method,
or dispensing method. In case that the nanocapsules 230 are
dispersed in the buffer layer 210 made in a film type, the
nanocapsule liquid crystal layer 200 is formed in a lamination
method. Accordingly, a process of forming a gap between first and
second substrates filled with a liquid crystal layer in the prior
art can be eliminated, and a process of forming a seal pattern to
prevent leakage of liquid crystal in the prior art can be
eliminated.
[0131] Thus, production efficiency can be improved.
[0132] Further, by eliminating the process of forming the alignment
layer, in case that the LCD 100 is applied to a touch display
device, curved display device or flexible display device, light
leakage, which occurs when a rubbing axis is off a desired
direction and thus arrangement of liquid crystal molecules goes
awry, can be reduced or prevented.
[0133] Thus, the LCD 100 can be applicable to a touch display
device, curved display device, or flexible display device.
[0134] Because the pixel and common electrodes 124 and 136 are
formed with a slanted plane, an awry arrangement of the liquid
crystal molecules 220 due to a collision in the process of
arranging the liquid crystal molecules 220 can be reduced or
prevented, and thus a light leakage caused by an awry arrangement
can be also reduced or prevented.
[0135] This can improve the transmittance of the LCD 100.
[0136] Further, since the liquid crystal molecules 220 are arranged
in parallel at a tilt angle of 1 degree to 5 degrees with respect
to the first substrate 112, rotation of the liquid crystal
molecules 220 can be easily made and thus a response time can be
further improved.
[0137] The LCD 100 of the first embodiment may be alternatively
configured to have a COT (color filter on transistor) structure, as
illustrated in FIG. 6, where the thin film transistor T and the
color filter 134 are formed together on the first substrate
112.
[0138] In this case, referring to FIGS. 3 and 6, a black matrix is
formed on a passivation layer that is on the thin film transistor
T, and has a lattice shape. Red, green and blue color filters are
formed on the black matrix and fill openings of the lattice of the
black matrix in the respective pixel regions P. The pixel electrode
124 is formed on the color filter, and the common electrode 136 is
formed on the second substrate 114 and faces the pixel with the
nanocapsule liquid crystal layer between the common electrode 136
and the pixel electrode 124.
[0139] Alternatively, as illustrated in FIG. 7, a COT type LCD may
be configured not to have a second substrate, and in this case, the
common electrode 136 may be formed on an inner surface of the
second polarizing plate 130.
Second Embodiment
[0140] FIGS. 8A and 8B are schematic views illustrating an LCD
according to a second embodiment of the present invention.
Explanations of parts similar to parts of the above first
embodiment may be omitted.
[0141] Referring to FIGS. 8A and 8B, the LCD (100 of FIG. 3) of the
second embodiment includes the liquid crystal panel 110 and the
backlight unit 160.
[0142] The liquid crystal panel 110 includes the first and second
substrates 112 and 114 facing each other, the nanocapsule liquid
crystal layer 200, and the first and second polarizing plates 120
and 130 on the outer surfaces of the first and second substrates
112 and 114, respectively.
[0143] The liquid crystal panel 110 may be a vertical alignment
(VA) mode liquid crystal panel. The thin film transistor (T of FIG.
3) and the pixel electrode 124 are formed on the inner surface of
the first substrate 112. The black matrix (132 of FIG. 3), the
color filters 134, and the common electrode 136 are formed on the
inner surface of the second substrate 114. An overcoat layer may be
formed covering the black matrix 132 and the color filters 134.
[0144] The negative type nematic liquid crystal molecules 220 of
the nanocapsule liquid crystal layer 200 are arranged
perpendicularly to the electric field that is perpendicular to the
plane of the first and second substrates 112 and 114, and a
refraction index in a direction perpendicular to the electric field
is manifested.
[0145] Accordingly, to realize a maximum brightness, the polarizing
axes of the first and second polarizing plates 120 and 130 are
attached to each make a 45 degree angle with the liquid crystal
molecules 220 perpendicular to the electric field.
[0146] The backlight unit 160 supplies a scattering light close to
a natural light to the liquid crystal panel 110.
[0147] One of the particular components of this second embodiment
is a phase retardation film 170 between the second substrate 114
and the second polarizing plate 130.
[0148] The phase retardation film 170 may be formed of a .lamda./4
wave plate (quarter wave plate).
[0149] In this regard, as illustrated in FIG. 8A, when a voltage is
off, a scattering light from the backlight unit 160 enters the
first polarizing plate 120 and a linearly polarized light parallel
with the polarizing axis of the first polarizing plate 120 passes
through and comes out from the first polarizing plate 120.
[0150] However, in the voltage-off state, the liquid crystal
molecules 220 are arranged randomly, the liquid crystal molecules
220 and the nano capsule 230 have different anisotropies in
refractive index from each other. Accordingly, optically isotropic
property is obtained.
[0151] Accordingly, the linearly polarized light from the first
polarizing plate 120 passes through the nanocapsule liquid crystal
layer 200 as is, and does not pass through the second polarizing
plate 130 having the polarizing axis perpendicular to the
polarizing axis of the first polarizing plate 120. Thus, a black is
displayed.
[0152] As illustrated in FIG. 8B, when voltages are applied to the
pixel electrode 124 and the common electrode 136, the liquid
crystal molecules 220 are arranged perpendicularly to the electric
field between the pixel and common electrodes 124 and 136.
[0153] Accordingly, the nanocapsule liquid crystal layer 200 has an
optical anisotropy.
[0154] Accordingly, a scattering light from the backlight unit 160
enters through the first polarizing plate 120 so that a linearly
polarized light comes out and other part is absorbed, and then a
linearly polarized light, which is parallel with the liquid crystal
molecules 220, out of the linearly polarized light coming out from
the first polarizing light 120, passes through the liquid crystal
layer 200.
[0155] Then, the linearly polarized light passing through the
liquid crystal layer 200 is modified by the phase retardation film
170 into a circularly polarized light, and then the circularly
polarized light is modified into a linearly polarized light, which
is parallel with the polarizing axis of the second polarizing plate
130, while passing through the second polarizing plate 130. Thus, a
white is displayed.
[0156] In this regard, since the LCD 100 of the second embodiment
includes the phase retardation film 170 between the second
substrate 114 and the second polarizing plate 130, a light leakage
can be reduced or prevented, and non-uniformity of brightness and
image can be reduced or prevented.
[0157] In more detail, the negative type liquid crystal molecules
220 randomly arranged collide one another without directivity in
the process that the molecules 220 are arranged perpendicularly to
the electric field induced between the pixel and common electrodes
124 and 136.
[0158] Because of this collision among the liquid crystal molecules
220, the liquid crystal molecules 220 are not arranged in parallel
with one another, and this causes a light leakage. Further, this
light leakage causes non-uniformity of brightness and image.
[0159] However, according to the phase retardation film 170 between
the second substrate 114 and the second polarizing plate 130 in the
second embodiment, the linearly polarized light from the
nanocapsule liquid crystal layer 200 is modified into the
circularly polarized light, which then enters the second polarizing
plate 130. Accordingly, light leakage can be reduced or prevented,
and thus non-uniformity of brightness and image can be reduced or
prevented.
[0160] As described above, the response time can be improved, and
the process of forming an alignment layer, the process of forming a
cell gap, the process of forming a seal pattern can be eliminated,
and thus production efficiency can be improved.
[0161] Further, the LCD 100 can be applied to a touch display
device, curved display device, or flexible display device.
[0162] Particularly, by providing the phase retardation film 170
between the second substrate 114 and the second polarizing plate
130, the linearly polarized light is modified by the phase
retardation film 170 into a circularly polarized light, which then
enters the second polarizing plate 130. Accordingly, a light
leakage can be reduced or prevented. Thus, non-uniformity of
brightness and image due to such a light leakage can be reduced or
prevented.
[0163] The LCD 100 of the second embodiment may be alternatively
configured to have a COT (color filter on transistor) structure, as
illustrated in FIG. 9, where the thin film transistor T and the
color filter 134 are formed together on the first substrate
112.
[0164] In this case, referring to FIGS. 3 and 9, a black matrix is
formed on a passivation layer that is on the thin film transistor
T, and has a lattice shape. Red, green and blue color filters are
formed on the black matrix and fill openings of the lattice of the
black matrix in the respective pixel regions P. The pixel electrode
124 is formed on the color filter, and the common electrode 136 is
formed on the second substrate 114 and faces the pixel with the
nanocapsule liquid crystal layer between the common electrode 136
and the pixel electrode 124.
[0165] Alternatively, as illustrated in FIG. 10, a COT type LCD may
be configured not to have a second substrate, and in this case, the
common electrode 136 may be formed on an inner surface of the phase
retardation film 170.
Third Embodiment
[0166] FIG. 11A is a schematic view illustrating an LCD according
to a third embodiment of the present invention. Explanations of
parts similar to parts of the above first and second embodiments
may be omitted.
[0167] Referring to FIG. 11A, the LCD (100 of FIG. 3) of the third
embodiment includes the liquid crystal panel 110 and the backlight
unit 160.
[0168] The liquid crystal panel 110 includes the first and second
substrates 112 and 114 facing each other, the nanocapsule liquid
crystal layer 200, and the first and second polarizing plates 120
and 130 on the outer surfaces of the first and second substrates
112 and 114, respectively.
[0169] The liquid crystal panel 110 may be a vertical alignment
(VA) mode liquid crystal panel. The thin film transistor (T of FIG.
3) and the pixel electrode 124 are formed on the inner surface of
the first substrate 112. The black matrix (132 of FIG. 3), the
color filters 134, and the common electrode 136 are formed on the
inner surface of the second substrate 114. An overcoat layer may be
formed covering the black matrix 132 and the color filters 134.
[0170] The pixel electrode 124 and the common electrode 136 have
first and second slits 180a and 180b, respectively.
[0171] In other words, the pixel electrodes 124 are spaced apart
from each other to form the first slits 180a, and similarly, the
common electrodes 136 are spaced apart from each other to form the
second slits 180b.
[0172] The first slit 180a has a width much less than a width of
the pixel electrode 124. In other words, the width of the pixel
electrode 124 is a few to a few tens of times the width of the
first slit 180a.
[0173] The first and second slits 180a and 180a alternate. It is
preferred that each first slit 180a is located at a center portion
of the corresponding common electrode 136 that is between the
neighboring second slits 180b, and each second slit 180b is located
at a center portion of the corresponding pixel electrode 124 that
is between the neighboring first slits 180a.
[0174] Accordingly, when voltages are applied to the pixel
electrode 124 and the common electrode 136, a fringe electric field
inclined from a direction perpendicular to the plane of the first
and second substrates 112 and 114 is realized.
[0175] Accordingly, the negative type liquid crystal molecules 220
are arranged perpendicularly to the fringe electric field between
the pixel and common electrodes 124 and 136, and a refraction index
perpendicular to the fringe electric field is manifested.
[0176] Accordingly, the nanocapsule liquid crystal layer 200 has an
optical anisotropy.
[0177] Accordingly, a scattering light from the backlight unit 160
enters through the first polarizing plate 120 so that a linearly
polarized light comes out and other part is absorbed, and then a
linearly polarized light, which is parallel with the liquid crystal
molecules 220, out of the linearly polarized light coming out from
the first polarizing light 120, passes through the liquid crystal
layer 200.
[0178] Then, a linearly polarized light, which is parallel with the
polarizing axis of the second polarizing plate 130, out of the
linearly polarized light coming out from the nanocapsule liquid
crystal layer 200 passes through the second polarizing plate 130,
and thus a white is displayed.
[0179] In this regard, since the LCD 100 of the third embodiment
includes the pixel electrode 124 and the common electrode 136
having the first slit 180a and the second slit 180b, respectively,
and generates the fringe electric field between the pixel and
common electrodes 124 and 136, the negative type liquid crystal
molecules 220 are arranged perpendicularly to the fringe electric
field. Accordingly, the liquid crystal molecules 220 can be
arranged more uniformly in parallel.
[0180] In other words, the liquid crystal molecules 220 randomly
arranged are more easily rotated and arranged because of the fringe
electric field.
[0181] Accordingly, an awry arrangement of the liquid crystal
molecules 220 because of collision among the molecules 220 in the
process that the molecules 220 are arranged perpendicularly can be
reduced or prevented, and thus a light leakage due to the awry
arrangement can be reduced or prevented.
[0182] Further, transmittance of the LCD 100 can be improved.
[0183] Further, since the liquid crystal molecules 220 are arranged
perpendicularly to the fringe electric field between the pixel and
common electrodes 124 and 136, rotation is more easily made and
thus response time is improved.
[0184] As described above, the response time can be improved, and
the process of forming an alignment layer, the process of forming a
cell gap, the process of forming a seal pattern can be eliminated,
and thus production efficiency can be improved.
[0185] Further, the LCD 100 is applicable to a touch display
device, curved display device, or flexible display device.
[0186] Particularly, since the pixel electrode 124 and the common
electrode 136 are configured to have the first slit 180a and the
second slit 180b, respectively, and generate the fringe electric
field between the pixel and common electrodes 124 and 136, the
negative type liquid crystal molecules 220 are arranged in parallel
with one another and perpendicularly to the fringe electric field,
and thus a light leakage can be reduced or prevented.
[0187] Thus, non-uniformity of brightness and image due to the
light leakage can be reduced or prevented.
[0188] Since the liquid crystal molecules 220 have substantially
uniform and consistent arrangement corresponding to the second slit
180b, when the second slit 180b is configured to have a bent shape
vertically symmetrical in the pixel region P, as illustrated in
FIG. 11B, four different domains at up, down, left and right sides
in each pixel region P can be obtained. In this case, the second
slit 180b is bent at a center portion of the pixel region P, and
the first slit 180a is bent like the second slit 180b.
[0189] Alternatively, even though not shown in the drawings, when a
plurality of second slits 180b are configured to be located and
bent to be vertically symmetrical in a pixel region, multi-domains
that are four times the number of the plurality of second slits
180b may be formed in each pixel region P.
Fourth Embodiment
[0190] FIG. 12A is a schematic view illustrating an LCD according
to a fourth embodiment of the present invention. Explanations of
parts similar to parts of the above first to third embodiments may
be omitted.
[0191] Referring to FIG. 12A, the LCD (100 of FIG. 3) of the fourth
embodiment includes the liquid crystal panel 110 and the backlight
unit 160.
[0192] The liquid crystal panel 110 includes the first and second
substrates 112 and 114 facing each other, the nanocapsule liquid
crystal layer 200, and the first and second polarizing plates 120
and 130 on the outer surfaces of the first and second substrates
112 and 114, respectively.
[0193] The liquid crystal panel 110 may be a vertical alignment
(VA) mode liquid crystal panel. The thin film transistor (T of FIG.
3) and the pixel electrode 124 are formed on the inner surface of
the first substrate 112. The black matrix (132 of FIG. 3), the
color filters 134, and the common electrode 136 are formed on the
inner surface of the second substrate 114. An overcoat layer may be
formed covering the black matrix 132 and the color filters 134.
[0194] The pixel electrode 124 has a pixel slit 190a, and a common
protrusion 190b is formed on the common electrode 136.
[0195] In other words, the pixel electrodes 124 are spaced apart
from each other to form the pixel slits 190a, and the common
protrusions 190b are spaced apart from each other on the common
electrode 136.
[0196] The common protrusion 190b may have a triangular shape in a
cross-section. Alternatively, the common electrode 190b may have
other shapes, for example, a semi-circular or semi-elliptical
shape.
[0197] The common protrusions 190b and the pixel slits 190a are
arranged alternately and parallel with each other in a pixel region
in a plan view, and are arranged alternately in a zigzag form with
the liquid crystal layer 200 therebetween in a cross-sectional
view.
[0198] In other words, the pixel slit 190a is located corresponding
to a separate region between the neighboring common protrusions
190b, and each common protrusion 190b are located at a center
portion of the corresponding pixel electrode 124 that is between
the neighboring pixel slits 190a.
[0199] Accordingly, when voltages are applied to the pixel
electrode 124 and the common electrode 136, a fringe electric field
inclined from a direction perpendicular to the plane of the first
and second substrates 112 and 114 is realized.
[0200] Accordingly, the negative type liquid crystal molecules 220
are arranged perpendicularly to the fringe electric field between
the pixel and common electrodes 124 and 136, and a refraction index
perpendicular to the fringe electric field is manifested.
[0201] Accordingly, the nanocapsule liquid crystal layer 200 has an
optical anisotropy.
[0202] Accordingly, a scattering light from the backlight unit 160
enters through the first polarizing plate 120 so that a linearly
polarized light comes out and other part is absorbed, and then a
linearly polarized light, which is parallel with the liquid crystal
molecules 220, out of the linearly polarized light coming out from
the first polarizing light 120, passes through the liquid crystal
layer 200.
[0203] Then, a linearly polarized light, which is parallel with the
polarizing axis of the second polarizing plate 130, out of the
linearly polarized light coming out from the nanocapsule liquid
crystal layer 200 passes through the second polarizing plate 130,
and thus a white is displayed.
[0204] In this regard, since the LCD 100 of the fourth embodiment
includes the pixel electrode 124 and the common electrode 136
having the pixel slit 190a and the common protrusion 190b,
respectively, and generates the fringe electric field between the
pixel and common electrodes 124 and 136, the negative type liquid
crystal molecules 220 are arranged perpendicularly to the fringe
electric field. Accordingly, the liquid crystal molecules 220 can
be arranged more uniformly in parallel.
[0205] In other words, the liquid crystal molecules 220 randomly
arranged are more easily rotated and arranged because of the fringe
electric field.
[0206] Accordingly, an awry arrangement of the liquid crystal
molecules 220 because of collision among the molecules 220 in the
process that the molecules 220 are arranged perpendicularly can be
reduced or prevented, and thus light leakage due to the awry
arrangement can be reduced or prevented.
[0207] Further, transmittance of the LCD 100 can be improved.
[0208] Further, since the liquid crystal molecules 220 are arranged
perpendicularly to the fringe electric field between the pixel and
common electrodes 124 and 136, rotation is more easily made and
thus response time is improved.
[0209] As described above, the response time can be improved, and
the process of forming an alignment layer, the process of forming a
cell gap, the process of forming a seal pattern can be eliminated,
and thus production efficiency can be improved.
[0210] Further, the LCD 100 can be applied to a touch display
device, curved display device, or flexible display device.
[0211] Particularly, since the pixel electrode 124 and the common
electrode 136 are configured to have the pixel slit 190a and the
common protrusion 190b, respectively, and generate the fringe
electric field between the pixel and common electrodes 124 and 136,
the negative type liquid crystal molecules 220 are arranged in
parallel with one another and perpendicularly to the fringe
electric field, and thus light leakage can be prevented.
[0212] Thus, non-uniformity of brightness and image due to the
light leakage can be reduced or prevented.
[0213] Since the liquid crystal molecules 220 have substantially
uniform and consistent arrangement corresponding to the common
protrusion 190b, when the common protrusion 190b is configured to
have a bent shape vertically symmetrical in the pixel region P, as
illustrated in FIG. 12B, four different domains at up, down, left
and right sides in each pixel region P can be obtained. In this
case, the pixel slit 190a is bent like the common protrusion
190b.
[0214] Fifth and sixth embodiments of the present invention, which
will now be described, relate to a reflective type LCD.
Fifth Embodiment
[0215] FIG. 13 is a perspective view illustrating an LCD according
to the fifth embodiment of the present invention. Explanations of
parts similar to parts of the above first to fourth embodiments may
be omitted.
[0216] Referring to FIG. 13, the LCD 100 includes a liquid crystal
panel 110, a polarizing plate 130, a phase retardation plate 175,
and a reflection plate 140. The LCD 100 using the reflection plate
140 is referred to as a reflective type LCD.
[0217] The liquid crystal panel 110 includes a first substrate 112,
a second substrate 114, and a nanocapsule liquid crystal layer 200
between the first and second substrates 112 and 114.
[0218] The first substrate 112 is referred to as a lower substrate
or an array substrate. A plurality of gate lines 116 and a
plurality of data lines 118 cross each other on an inner surface of
the first substrate 112 to define a plurality of pixel regions
P.
[0219] A thin film transistor T is formed near the crossing portion
of the gate and data lines 116 and 118, and is connected to a pixel
electrode 124 in the pixel region P.
[0220] The second substrate 114 is referred to as an upper
substrate or a color filter substrate. A black matrix 132 is on an
inner surface of the second substrate 114, and shields a
non-display element such as the gate line 116, the data line 118,
and the thin film transistor T exposing the pixel electrode 124.
The black matrix 132 has a lattice shape surrounding the pixel
region P.
[0221] Red, green and blue color filters 134 fill openings of the
black matrix 132 corresponding to the respective pixel regions P. A
common electrode 136 covers the black matrix 132 and the color
filters 134.
[0222] Even though not shown in the drawings, the first substrate
112 has an area greater than that of the second substrate 114 so
that a peripheral portion of the first substrate 112 is exposed
outside the second substrate 114. In the exposed portion of the
first substrate 112, data pads 118a connected to the respective
data lines 118, and gate pads (not shown) connected to the
respective gate lines 116 are formed.
[0223] When a gate line 116 is selected and supplied with a turn-on
gate signal i.e., high-level gate signal, the thin film transistor
T connected to the selected gate line 116 is turned on and an image
data signal is transferred to the pixel electrode 124 through the
data line 118. Accordingly, an electric field is induced between
the pixel electrode 124 and the common electrode 136 and controls
liquid crystal molecules 220 of the nanocapsule liquid crystal
layer 200, and thus light transmittance is changed to display
images.
[0224] The polarizing plate 130 is attached on an outer surface of
the second substrate 114.
[0225] The phase retardation plate 175 is located between the
second substrate 114 and the polarizing plate 130. The phase
retardation plate 175 may be a .lamda./4 plate (a quarter wave
plate).
[0226] It is preferred that three refractive indices nx, ny and nz
of the phase retardation plate 175 meet the following relation:
nx=ny>nz. The phase retardation plate 175 and the polarization
plate 130 may be formed as one body.
[0227] The reflection plate 140 is located on an outer surface of
the first substrate 112. The reflection plate 140 reflects an
external light from the outside into the liquid crystal panel
110.
[0228] The reflection plate 140 may be fat lied of a metal material
such as aluminum (Al) to increase reflectance.
[0229] Alternatively, the reflection plate 140 may be located
between the first substrate 112 and the nanocapsule liquid crystal
layer 200. In this case, the reflection plate 140 may function as a
reflection electrode and have an embossing pattern for diffused
reflection.
[0230] The nanocapsule liquid crystal layer 200 is an optically
isotropic type liquid crystal layer in a normal state. Accordingly,
when no electric field between the pixel electrode 124 and the
common electrode 136 is applied to the nanocapsule liquid crystal
layer 200, the nanocapsule liquid crystal layer 200 is optically
isotropic, and when an electric field is applied, the nanocapsule
liquid crystal layer 200 has a birefringence property in a
direction perpendicular to the applied electric field.
[0231] In other words, in case that the liquid crystal molecules
220 are negative type nematic liquid crystal molecules, the liquid
crystal molecules 220 are arranged perpendicularly to an electric
field to generate a birefringence. In case that the liquid crystal
molecules 220 are positive type nematic liquid crystal molecules,
the liquid crystal molecules 220 are arranged in parallel with an
electric field to generate a birefringence property.
[0232] Accordingly, when an electric field is applied, the
nanocapsule liquid crystal layer 200 has an optically uniaxial
property
[0233] In more detail, the liquid crystal molecules 220 are
contained within the capsule 230 having a nanosize, and the liquid
crystal molecules 220 are irregularly arranged in the nanocapsule
230.
[0234] The nanocapsule 230 may have about 5% to about 95% of a
total volume of the nanocapsule liquid crystal layer 200, and
preferably, may have about 25% to about 65% of the total volume of
the nanocapsule liquid crystal layer 200. The buffer layer 210
occupies the rest of the total volume.
[0235] The buffer layer 210 may be made of a transparent or
semi-transparent material and have water-solubility,
fat-solubility, or mixture of water-solubility and fat-solubility.
The buffer layer 210 may be heat cured or UV cured.
[0236] The buffer layer 210 may have an additive to increase
strength and reduce curing time.
[0237] The nanocapsule 230 may have a diameter of about 1 nm to
about 320 nm, and preferable, about 30 nm to about 100 nm.
[0238] Since the nanocapsule 230 has a diameter less than any
wavelengths of visible light, there occurs substantially no optical
change due to refractive index, and optically isotropic property
can be obtained. Further, scattering of visible light can be
reduced or minimized.
[0239] Particularly, when the nanocapsule 230 is formed with a
diameter of about 100 nm or less, high contrast ratio can be
obtained.
[0240] A thickness of the nanocapsule liquid crystal layer 200
(i.e., a cell gap) is preferably about 1 um to about 10 um, and
more preferably about 2 um to about 5 um.
[0241] In case that the cell gap is 2 um or less, it is difficult
to externally recognize a difference in light transmittance.
[0242] In case that the cell gap is 5 um or more, a distance
between electrodes is great, and thus high power consumption is
required. Further, an overall thickness of the liquid crystal panel
110 increases, and thus it is difficult to provide an LCD having
lightweight and thin profile.
[0243] The irregularly arranged liquid crystal molecules 220 and
the nanocapsule 230 have different refractive indices, and thus a
light scattering may be caused at the interface therebetween.
Accordingly, when light passes through the interface, the light is
scattered and becomes opaque in milk white.
[0244] However, when an electric field is applied to the
nanocapsule liquid crystal layer 200, the liquid crystal molecules
220 filling the nanocapsule 230 are regularly arranged.
[0245] In this state, the refractive index of the liquid crystal
molecules 220 is changed. In order to reduce or minimize a light
scattering at the interface between the nanocapsule 230 and the
liquid crystal molecules 220, the nanocapsule 230 and the regularly
arranged liquid crystal molecules 220 are formed such that they
have refractive indices that are substantially close to each other,
Therefore, the nanocapsule liquid crystal layer 200 can be seen
transparent.
[0246] In this case, it is preferred that a difference between the
refractive index of the nanocapsule 220 and the refractive index of
the liquid crystal molecule 220 is within about .+-.0.1. The
average refractive index (n) of the liquid crystal molecule 220 may
be defined as follows: n=[(ne+2*no)/3] (where ne is a refractive
index of a major axis of the liquid crystal molecule 220, and no is
a refractive index of a minor axis of the liquid crystal molecule
220).
[0247] Accordingly, the LCD 100 including the nanocapsule liquid
crystal layer 200 can be used as a display device, with its
transmittance changing according to a variation of the voltage
applied.
[0248] Further, since the nanocapsule liquid crystal layer 200 does
not have an initial alignment to be optically anisotropic,
alignment of liquid crystal molecules may not be required, and thus
no alignment layer may be needed in the LCD 100, and also,
processes for forming an alignment layer such as rubbing may not be
needed.
[0249] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of, for example, liquid crystal, the
nanocapsule liquid crystal layer 200 may be formed, for example, by
a printing method, coating method, or dispensing method. In case
that the nanocapsules 230 are dispersed in the buffer layer 210
made in a film type, the nanocapsule liquid crystal layer 200 may
be formed, for example, by a lamination method. Accordingly, a
process of forming a gap between the first and second substrates
filled with the liquid crystal layer (50 of FIG. 1) in the prior
art can be eliminated, and a process of forming the seal pattern
(70 of FIG. 1) in the prior art can be eliminated.
[0250] Therefore, production efficiency can be improved.
[0251] Further, even when an external force such as a user's touch
is applied to the LCD 100 of the embodiment, the liquid crystal
molecules 220 are in the nanocapsule 230 having a size less than
the wavelength of visible light, thus there is substantially no
influence of visible light, and thus a light leakage due to the
external force can be reduced or prevented.
[0252] Accordingly, in case that the LCD 100 of the embodiment is
applied to a flexible display device, even when an external force
is applied to the LCD 100, because of the nanocapsule 230 having a
size less than the wavelength of visible light, a light leakage due
to the external force can be reduced or prevented.
[0253] Further, when the electric field is induced between the
first and second substrates 112 and 114, the liquid crystal
molecules 220 are dynamically rotated, and thus response speed can
be fast.
[0254] FIGS. 14A and 14B are schematic views illustrating an image
display principle of the LCD according to the fifth embodiment of
the present invention, and FIGS. 15A and 15B are schematic views
illustrating variation of light in the states of FIGS. 14A and 14B,
respectively.
[0255] Referring to FIGS. 14A to 15B, the liquid crystal panel 110
includes the pixel electrode 124 and the common electrode 136 to
generate a vertical electric field. The liquid crystal molecules
220 are negative type nematic liquid crystal molecules.
[0256] In the LCD 100, the polarizing plate 130 is located close to
the side upon which an external light is incident, and the phase
retardation plate 175, the liquid crystal panel 110 and the
reflection plate 140 are sequentially arranged below the polarizing
plate 130.
[0257] The phase retardation plate 120 may be between the second
substrate 114 and the nanocapsule liquid crystal layer 200. The
reflection plate 140 may be between the first substrate 112 and the
nanocapsule liquid crystal layer 200.
[0258] The thin film transistor T and the pixel electrode 124 are
formed on an inner surface of the first substrate 112. The black
matrix 132, the color filter 134 and the common electrode 136 are
formed on an inner surface of the second substrate 114.
[0259] The liquid crystal molecules 220 are arranged
perpendicularly to an electric field that is vertical to the first
and second substrates 112 and 114, and a refractive index in a
direction perpendicular to the electric field is manifested.
[0260] Referring to FIGS. 14A and 15A, when no voltage is applied
to the liquid crystal panel 110, the liquid crystal molecules 220
are arranged randomly, the liquid crystal molecules 220 and the
nano capsule 230 have different anisotropies in refractive index
from each other. Accordingly, optically isotropic property is
obtained.
[0261] Accordingly, out of an external light, the polarizing plate
130 transmits a first linearly polarized light parallel with a
polarizing axis of the polarizing plate 130 and absorbs other
light. The first linearly polarized is modified into a circularly
polarized light (e.g., a left-hand circularly polarized light)
while passing through the phase retardation plate 175.
[0262] Then, the left-hand circularly polarized light passes
through the nanocapsule liquid crystal layer 200 as is, and then is
reflected by the reflection plate 140 and modified into a
right-hand circularly polarized light.
[0263] The right-hand circularly polarized light passes through the
nanocapsule liquid crystal layer 200 as is, and then enters the
phase retardation plate 175. While passing through the phase
retardation plate 175, the right-hand circularly polarized light is
modified into a second linearly polarized light that is
perpendicular to the first linearly polarized light.
[0264] The second polarized light does not pass through the
polarizing plate 130, and thus a black is displayed.
[0265] Referring to FIGS. 14B and 15B, when a voltage is applied to
the pixel electrode 124 and the common electrode 136, the liquid
crystal molecules 220 are arranged perpendicularly to the electric
field between the pixel and common electrodes 124 and 136.
Accordingly, optically anisotropic property is obtained.
[0266] Accordingly, out of an external light, the polarizing plate
130 transmits a first linearly polarized light parallel with a
polarizing axis of the polarizing plate 130 and absorbs other
light. The first linearly polarized is modified into a left-hand
circularly polarized light while passing through the phase
retardation plate 175.
[0267] Then, while passing through the nanocapsule liquid crystal
layer 200, the left-hand circularly polarized light is
phase-retarded and thus a second linearly polarized light
perpendicular to the first linearly polarized light comes out from
the nanocapsule liquid crystal layer 200.
[0268] Then, the second linearly polarized light is reflected by
the reflection plate 140, and then is phase-retarded passing
through the nanocapsule liquid crystal layer 200. Accordingly, a
right-hand circularly polarized light comes out from the
nanocapsule liquid crystal layer 200, and then is modified into the
first linearly polarized light while passing through the phase
retardation plate 175.
[0269] Then, the first linearly polarized light passes through the
polarizing plate 130, and thus a white is displayed.
Sixth Embodiment
[0270] FIGS. 16A and 16B are schematic views illustrating an image
display principle of the LCD according to the sixth embodiment of
the present invention. Explanations of parts similar to parts of
the first to fifth embodiments may be omitted.
[0271] Referring to FIGS. 16A and 16B, the liquid crystal panel 110
includes the pixel electrode 124 and the common electrode 136 to
generate an in-plane electric field which is substantially parallel
with the first and second substrates 112 and 114. The liquid
crystal molecules 220 are positive type nematic liquid crystal
molecules.
[0272] In the LCD 100, the polarizing plate 130 is located close to
the side upon which an external light is incident, and the phase
retardation plate 175, the liquid crystal panel 110 and the
reflection plate 140 are sequentially arranged below the polarizing
plate 130.
[0273] The phase retardation plate 120 may be provided between the
second substrate 114 and the nanocapsule liquid crystal layer 200.
The reflection plate 140 may be provided between the first
substrate 112 and the nanocapsule liquid crystal layer 200.
[0274] The liquid crystal panel 110 includes the first and second
substrates 112 and 114, and the nanocapsule liquid crystal layer
200 therebetween. The liquid crystal panel 110 is an IPS (in-plane
switching) type panel, in which the thin film transistor T, the
pixel electrode 124, and the common electrode 136 are formed on an
inner surface of the first substrate 112. The black matrix 132 and
the color filter 134 are formed on an inner surface of the second
substrate 114. The pixel and common electrode 112 and 114 on the
same substrate 112 generates an in-plane electric field parallel
with the first and second substrates 112 and 114.
[0275] The liquid crystal molecules 220 are arranged parallel to
the in-plane electric field that is parallel to the first and
second substrates 112 and 114, and a refractive index in a
direction parallel to the electric field is manifested.
[0276] Referring to FIG. 16A, when no voltage is applied to the
liquid crystal panel 110, an external light is finally blocked by
the polarizing plate 130, and thus a black is displayed.
[0277] Referring to FIG. 16B, when a voltage is applied to the
pixel electrode 124 and the common electrode 136, the liquid
crystal molecules 220 are uniformly arranged parallel to the
electric field between the pixel and common electrodes 124 and
136.
[0278] Accordingly, an external light passes through the polarizing
plate 130, phase retardation plate 175, and the nanocapsule liquid
crystal layer 200, then is reflected by the reflection plate 140,
then passes through the nanocapsule liquid crystal layer 200, the
phase retardation plate 175 and the polarizing plate 130, and thus
a white is displayed.
[0279] The reflective type LCD 100 according to the above fifth or
sixth embodiment may be alternatively configured to have a COT
(color filter on transistor) structure, where the thin film
transistor T and the color filter 134 are formed together on the
first substrate 112.
[0280] In this case, a black matrix is formed on a passivation
layer that is on the thin film transistor T, and has a lattice
shape. Red, green and blue color filters are formed on the black
matrix and fill openings of the lattice of the black matrix in the
respective pixel regions P. The pixel electrode 124 is formed on
the color filter, and the common electrode 136 is formed on the
first substrate 112 or second substrate 114 corresponding to the
pixel electrode 124.
[0281] Alternatively, a COT type LCD may be configured not to have
a second substrate, and in this case, the common electrode 136 of
the fifth embodiment may be formed on an inner surface of the phase
retardation plate 175.
[0282] In the reflective type LCD as above, by using the
nanocapsule liquid crystal layer 200, where the nanocapsule 230
each filled with the randomly arranged nematic liquid crystal
molecules 220 are dispersed in the buffer layer 210, between the
first and second substrates 112 and 114, a response time can be
fast compared to the prior art LCD.
[0283] Further, since the nanocapsule liquid crystal layer 200 does
not have an initial alignment to be optically anisotropic,
alignment of liquid crystal molecules may not be required, and thus
no alignment layer may be needed in the LCD 100, and also,
processes for forming an alignment layer such as rubbing may not be
needed.
[0284] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of, for example, liquid crystal, the
nanocapsule liquid crystal layer 200 may be formed, for example, by
a printing method, coating method, or dispensing method. In case
that the nanocapsules 230 are dispersed in the buffer layer 210
made in a film type, the nanocapsule liquid crystal layer 200 may
be formed, for example, by a lamination method. Accordingly, a
process of forming a gap between the first and second substrates
filled with the liquid crystal layer in the prior art can be
eliminated, and a process of forming the seal pattern in the prior
art can be eliminated.
[0285] Therefore, production efficiency can be improved.
[0286] Further, even when an external force such as a user's touch
is applied to the LCD 100 of the embodiment, the liquid crystal
molecules 220 are in the nanocapsule 230 having a size less than
the wavelength of visible light, thus there is substantially no
influence of visible light, and thus light leakage due to the
external force can be prevented.
[0287] Accordingly, in case that the LCD 100 of the embodiment is
applied to a flexible display device, even when an external force
is applied to the LCD 100, because of the nanocapsule 230 having a
size less than the wavelength of visible light, light leakage due
to the external force can be prevented.
[0288] Seventh to Eleventh embodiments of the present invention,
which will now be described, relate to a flexible type LCD.
Seventh to Ninth Embodiments
[0289] FIGS. 17A and 17B are schematic views illustrating an image
display principle of an LCD according to a seventh embodiment of
the present invention, and FIGS. 17C and 17D are schematic views
illustrating an LCD according to eighth and ninth embodiments of
the present invention, respectively. Explanations of parts similar
to parts of the first to sixth embodiments may be omitted.
[0290] Referring to FIGS. 17A-17B, the flexible type LCD includes a
liquid crystal panel 110 and a backlight unit 160.
[0291] The liquid crystal panel 110 includes a nanocapsule liquid
crystal layer 200 on a substrate 112.
[0292] The substrate 112 is referred to as an array substrate. A
plurality of gate lines and a plurality of data lines cross each
other on an inner surface of the first substrate to define a
plurality of pixel regions P. A thin film transistor is formed near
the crossing portion of the gate and data lines. A black matrix is
formed on the thin film transistor with a passivation layer
therebetween, and has a lattice shape exposing the pixel regions.
Red, green and blue color filters 134 fill openings of the black
matrix 132 corresponding to the respective pixel regions.
[0293] A pixel electrode 124 connected to the thin film transistor
and a common electrode 136 spaced apart from the pixel electrode
124 are formed on the color filters 134.
[0294] Liquid crystal molecules 220 of the nanocapsule liquid
crystal layer 200 are driven by an in-plane electric field between
the pixel and common electrodes 124 and 136.
[0295] A polarizing plate 130 is attached onto the nanocapsule
liquid crystal layer 200.
[0296] A backlight unit 160 is below the liquid crystal panel 110
and supplies light to the liquid crystal panel 110.
[0297] The backlight unit 160 includes an LED assembly 129 along a
length direction of a side of the backlight unit 160, a reflective
polarizing film 127, a reflection plate 125 in white or silver
color, a light guide plate 123 and at least one optical sheet
121.
[0298] The LED assembly 129 is located facing a side of the light
guide plate 123 upon which the light is incident, and includes a
plurality of LEDs 129a and a PCB (printed circuit board) 129b on
which the plurality of LEDs 129a are mounted, with being spaced
apart from each other.
[0299] The reflective polarizing film 127 is located on the front
of the LEDs 129a. Out of light emitted from the LEDs 129a, the
reflective polarizing film 127 transmits a predetermined polarized
light, and reflects and recycles other part, and thus light
efficiency of the flexible type LCD can be improved.
[0300] The reflective polarizing film 127 may be formed using a
polarizer having a predetermined polarizing axis embedded in a
lamination structure of dielectric thin films having different
refractive indices, or using a wire grid polarizer in which fine
line type metal patterns of a high reflective material, such as
aluminum (Al), silver (Ag) or chromium (Cr) are arranged in
parallel along a direction on a base film.
[0301] The reflective polarizing film 127 has a polarizing axis
perpendicular to the polarizing axis of the polarizing plate
130.
[0302] Accordingly, all light emitted from the LED assembly 129 are
supplied to the liquid crystal panel 110 substantially without loss
of light.
[0303] In other words, out of the light from the LED assembly 129,
a portion of the light having the same polarizing axis as the
reflective polarizing film 127 is transmitted, and the other
portion is reflected by the reflective polarizing film 127. A first
polarized light PL1 out of the light emitted from the LED 129a is
transmitted by the reflective polarizing plate 127 and enters into
the light guide plate 123 via the light incidence surface of the
light guide plate 123. A second polarized light PL2, which is
perpendicular to the first polarized light PL1, out of the light
from the LED 129a is reflected by the reflective polarizing film
127 and is recycled into a scattering light.
[0304] A first polarized light PL1 out of the recycled scattering
light is transmitted by the reflective polarizing film 127, and a
second polarized light PL2 out of the recycled scattering light is
recycled again into a scattering light. Accordingly, light
efficiency can be improved.
[0305] A specific linearly polarized light entering the light guide
plate 123 travels in the light guide plate 123 and evenly spreads
over a large area of the light guide plate 123, and thus a plane
light is supplied to the liquid crystal panel 110.
[0306] The light guide plate 123 may include a specific-shaped
pattern at a bottom surface to supply a uniform plane light.
[0307] The reflection plate 125 is located below the light guide
plate 123, and reflects light coming out from the bottom surface of
the light guide plate 123 to the liquid crystal panel 110, and thus
brightness of light is improved.
[0308] The at least one optical sheet 121 may include a diffusion
sheet, and at least one light concentration sheet. The at least one
optical sheet 121 diffuses and/or concentrates light to supply more
uniform plane light to the liquid crystal panel 110.
[0309] A cold cathode fluorescent lamp (CCFL), or external
electrode fluorescent lamp (EEFL) may be uses as a light source
instead of the LED 129a.
[0310] The liquid crystal panel 110 and the backlight unit 160 are
attached to each other using a lamination process. In this process,
an adhesive is interposed between the liquid crystal panel 110 and
the backlight unit 120 to eliminate an air gap therebetween, and
thus loss of light due to the air gap can be reduced or
prevented.
[0311] The nanocapsule liquid crystal layer 200 is an optically
isotropic type liquid crystal layer in a normal state. Accordingly,
when no electric field between the pixel electrode 124 and the
common electrode 136 is applied to the nanocapsule liquid crystal
layer 200, the nanocapsule liquid crystal layer 200 is optically
isotropic, and when an electric field is applied, the nanocapsule
liquid crystal layer 200 has a birefringence property in a
direction perpendicular to the applied electric field
[0312] In other words, in case that the liquid crystal molecules
220 are negative type nematic liquid crystal molecules, the liquid
crystal molecules 220 are arranged perpendicularly to an electric
field to generate a birefringence property. In case that the liquid
crystal molecules 220 are positive type nematic liquid crystal
molecules, the liquid crystal molecules 220 are arranged in
parallel with the electric field to generate a birefringence
property.
[0313] Accordingly, when an electric field is applied, the
nanocapsule liquid crystal layer 200 has an optically uniaxial
property
[0314] In more detail, the liquid crystal molecules 220 are
contained within the capsule 230 having a nanosize, and the liquid
crystal molecules 220 are irregularly arranged in the nanocapsule
230.
[0315] The nanocapsule 230 may have about 5% to about 95% of a
total volume of the nanocapsule liquid crystal layer 200, and
preferably, may have about 25% to about 65% of the total volume of
the nanocapsule liquid crystal layer 200. The buffer layer 210
occupies the rest of the total volume.
[0316] The buffer layer 210 may be made of a transparent or
semi-transparent material and have water-solubility,
fat-solubility, or mixture of water-solubility and fat-solubility.
The buffer layer 210 may be heat cured or UV cured.
[0317] The buffer layer 210 may have an additive to increase
strength and reduce curing time.
[0318] The nanocapsule 230 may have a diameter of about 1 nm to
about 320 nm, and preferable, about 30 nm to about 100 nm.
[0319] Since the nanocapsule 230 has a diameter less than any
wavelengths of visible light (i.e., with a diameter of about 320 nm
or less), there occurs substantially no optical change due to
refractive index, and optically isotropic property can be obtained.
Further, scattering of visible light can be reduced or
minimized.
[0320] Particularly, when the nanocapsule 230 is formed with a
diameter of about 100 nm or less, high contrast ratio can be
obtained.
[0321] A thickness of the nanocapsule liquid crystal layer 200
(i.e., a cell gap) is preferably about 1 um to about 10 um, and
more preferably about 2 um to about 5 um.
[0322] In case that the cell gap is 2 um or less, it is difficult
to externally recognize a difference in light transmittance.
[0323] In case that the cell gap is 5 um or more, a distance
between electrodes is great, and thus high power consumption is
required. Further, an overall thickness of the liquid crystal panel
110 increases, and thus it is difficult to provide an LCD having
lightweight and thin profile.
[0324] Referring to FIG. 17A, when no voltage is applied to the
liquid crystal panel 110, the liquid crystal molecules 220 are
arranged randomly, the liquid crystal molecules 220 and the nano
capsule 230 have different anisotropies in refractive index from
each other. Accordingly, optically isotropic property is
obtained.
[0325] Accordingly, a linearly polarized light emitted from the
backlight unit 160 passes through the nanocapsule liquid crystal
layer 200 as is, and then does not pass through the polarizing
plate 130 perpendicular to the polarizing axis of the linearly
polarized light from the backlight unit 160. Thus, a black is
displayed.
[0326] Referring to FIG. 17B, when a voltage is applied between the
pixel electrode 124 and the common electrode 136, the liquid
crystal molecules 220 are arranged parallel with the electric field
between the pixel and common electrodes 124 and 136. Accordingly, a
linearly polarized light, parallel with the liquid crystal
molecules 220, out of the linearly polarized light emitted from the
backlight unit 160 passes through the nanocapsule liquid crystal
layer 200.
[0327] Then, a linearly polarized light, parallel with the
polarizing axis of the polarizing plate 130, out of the linearly
polarized light passing through the nanocapsule liquid crystal
layer 200 passes through the polarizing plate 130. Thus, a white is
displayed.
[0328] In this case, it is preferred that a difference between the
refractive index of the nanocapsule 220 and the refractive index of
the liquid crystal molecule 220 is within about .+-.0.1. The
average refractive index (n) of the liquid crystal molecule 220 may
be defined as follows: n=[(ne+2*no)/3] (where ne is a refractive
index of a major axis of the liquid crystal molecule 220, and no is
a refractive index of a minor axis of the liquid crystal molecule
220).
[0329] Accordingly, the LCD including the nanocapsule liquid
crystal layer 200 can be used as a display device, with its
transmittance changing according to a variation of the voltage
applied.
[0330] Further, since the nanocapsule liquid crystal layer 200 does
not have an initial alignment to be optically anisotropic,
alignment of liquid crystal molecules may not be required, and thus
no alignment layer may be needed in the LCD 100, and also,
processes for forming an alignment layer such as rubbing may not be
needed.
[0331] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of, for example, liquid crystal, the
nanocapsule liquid crystal layer 200 may be formed, for example, by
a printing method, coating method, or dispensing method. In case
that the nanocapsules 230 are dispersed in the buffer layer 210
made in a film type, the nanocapsule liquid crystal layer 200 may
be formed, for example, by a lamination method. Accordingly, a
process of forming a gap between the first and second substrates
filled with the liquid crystal layer in the prior art can be
eliminated, and a process of forming the seal pattern in the prior
art can be eliminated.
[0332] Therefore, production efficiency can be improved.
[0333] Further, even when an external force such as a user's touch
is applied to the LCD of the embodiment, the liquid crystal
molecules 220 are in the nanocapsule 230 having a size less than
the wavelength of visible light, thus there is substantially no
influence of visible light, and thus light leakage due to the
external force can be reduced or prevented.
[0334] Accordingly, in case that the LCD of the embodiment is
applied as a flexible display device, even when the external force
is applied to the LCD, because of the nanocapsule 230 having a size
less than the wavelength of visible light, light leakage due to the
external force can be reduced or prevented.
[0335] Particularly, since the flexible type LCD of the embodiment
includes the reflective polarizing film 127 on the front of the LED
assembly 129, the linearly polarized light from the backlight unit
160 is supplied to the liquid crystal panel 110. Accordingly, one
polarizing plate can be eliminated.
[0336] Thus, the LCD of the embodiment may not require the second
substrate (4 of FIG. 2) and one polarizing plate (20 of FIG. 2) in
the prior art, thus a total thickness of the liquid crystal panel
110 can be reduced, and thus the LCD can have lightweight and thin
profile and can be effectively applied as a flexible type display
device.
[0337] Alternatively, since the nanocapsule liquid crystal layer
200 is formed with the nanocapsules 230 dispersed in the buffer
layer of liquid crystal or in a film type, another flexible type
LCD of an eighth embodiment may be provided as illustrated in FIG.
17C, in which the nanocapsule liquid crystal layer 200 is located
facing the backlight unit 160, and in this case, the polarizing
plate 130 is located on the top surface of the substrate 112.
[0338] Alternatively, another flexible type LCD of the ninth
embodiment may be provided as illustrated in FIG. 17D, in which the
nanocapsule liquid crystal layer 200 is located facing the
backlight unit 160 similarly to the above eighth embodiment.
Further, a touch panel 150 is located on the liquid crystal panel
110 with the polarizing plate 130, and includes first electrode
151, an insulating layer 155, and a second electrode 153. Thus, the
flexible type LCD of this embodiment can be applied to a touch type
display device.
[0339] In the above seventh to ninth embodiments, in addition to
the reflective polarizing film 127, a wire-grid lattice may be
formed in the light guide plate 123 so that only a specific
linearly polarized light passes through the light guide plate 123
and then is supplied to the liquid crystal panel 110.
Alternatively, in addition to the reflective polarizing film 127, a
polarization separation layer may be formed on the light guide
plate 123 so that only a specific linearly polarized light passes
through the light guide plate 123 and then is supplied to the
liquid crystal panel 110.
Tenth Embodiment
[0340] FIG. 18 is a schematic view illustrating a flexible type LCD
according to the tenth embodiment of the present invention.
Explanations of parts similar to parts of the first to ninth
embodiments may be omitted.
[0341] Referring to FIG. 18, the flexible type LCD includes a
liquid crystal panel 110 and a backlight unit 160. The liquid
crystal panel 110 includes a nanocapsule liquid crystal layer 200
on a substrate 112, on which the thin film transistor and the color
filter 134 are formed.
[0342] Further, the pixel electrode 124 and the common electrode
136 are formed on the substrate 112.
[0343] The nanocapsule liquid crystal layer 200 includes the
nanocapsules 230 filled with the liquid crystal molecules 220 and
dispersed in the buffer layer 210.
[0344] The polarizing plate 130 is attached onto the polarizing
plate 130, and the backlight unit 160 is below the liquid crystal
panel 110.
[0345] The backlight unit 160 includes non-polar or semi-polar LEDs
300 arranged along a length direction of a side of the backlight
unit 160, the reflection plate 125, the light guide plate 123 on
the reflection plate 125, and at least one optical sheet 121.
[0346] The non-polar or semi-polar LEDs 300 as light sources are
located at and faces the surface of the light guide plate 123 upon
which the light is incident.
[0347] The non-polar or semi-polar LED 300 has a property of
emitting light polarized in a specific direction.
[0348] The non-polar or semi-polar LED 300 is different from a
polar LED including a compound semiconductor layer grown in a
c-axis direction. For example, by growing a nitride semiconductor
layer of a GaN group material, such as GaN, InGaN, AlGaN, AlInGaN
or the like, on a m-surface or a-surface of a GaN substrate, a
non-polar or semi-polar LED without spontaneous polarization or
piezoelectric polarization may be formed.
[0349] Further, an LED using a nitride semiconductor layer may be
formed to emit light of wavelength in a range of UV light to
visible light by adjusting a composition ratio of the nitride
semiconductor.
[0350] A specific linearly polarized light entering the light guide
plate 123 from the non-polar or semi-polar LED 300 travels in the
light guide plate 123 and evenly spreads over a large area of the
light guide plate 123, and thus a plane light is supplied to the
liquid crystal panel 110.
[0351] The light guide plate 123 may include a specific-shaped
pattern at a bottom surface to supply a uniform plane light.
[0352] The reflection plate 125 is located below the light guide
plate 123, and reflects light coming out from the bottom surface of
the light guide plate 123 to the liquid crystal panel 110, and thus
brightness of light is improved.
[0353] The at least one optical sheet 121 may include a diffusion
sheet, and at least one light concentration sheet. The at least one
optical sheet 121 diffuses and/or concentrates light to supply more
uniform plane light to the liquid crystal panel 110.
[0354] When no voltage is applied to the liquid crystal panel 110,
the liquid crystal molecules 220 are arranged randomly, the liquid
crystal molecules 220 and the nano capsule 230 have different
anisotropies in refractive index from each other. Accordingly,
optically isotropic property is obtained.
[0355] Accordingly, a linearly polarized light emitted from the
backlight unit 160 passes through the nanocapsule liquid crystal
layer 200 as is, and then does not pass through the polarizing
plate 130 perpendicular to the polarizing axis of the linearly
polarized light from the backlight unit 160. Thus, a black is
displayed.
[0356] When a voltage is applied between the pixel electrode 124
and the common electrode 136, the liquid crystal molecules 220 are
arranged parallel with the electric field between the pixel and
common electrodes 124 and 136. Accordingly, a linearly polarized
light, parallel with the liquid crystal molecules 220, out of the
linearly polarized light emitted from the backlight unit 160 passes
through the nanocapsule liquid crystal layer 200.
[0357] Then, a linearly polarized light, parallel with the
polarizing axis of the polarizing plate 130, out of the linearly
polarized light passing through the nanocapsule liquid crystal
layer 200 passes through the polarizing plate 130. Thus, a white is
displayed.
Eleventh Embodiment
[0358] FIG. 19A is a schematic view illustrating a flexible type
LCD according to an eleventh embodiment of the present invention,
and FIG. 19B is a schematic perspective view illustrating an
optical fiber of an optical fiber type light guide plate of FIG.
19A. Explanations of parts similar to parts of the first to tenth
embodiments may be omitted.
[0359] Referring to FIGS. 19A and 19B, the flexible type LCD
includes a liquid crystal panel 110 and a backlight unit 160. The
liquid crystal panel 110 includes a nanocapsule liquid crystal
layer 200 on a substrate 112, on which the thin film transistor and
the color filter 134 are formed.
[0360] Further, the pixel electrode 124 and the common electrode
136 are formed on the substrate 112.
[0361] The nanocapsule liquid crystal layer 200 includes the
nanocapsules 230 filled with the liquid crystal molecules 220 and
dispersed in the buffer layer 210.
[0362] The polarizing plate 130 is attached onto the polarizing
plate 130, and the backlight unit 160 is below the liquid crystal
panel 110.
[0363] The backlight unit 160 includes non-polar or semi-polar LEDs
300 arranged along a length direction of a side of the backlight
unit 160, the reflection plate 125, a light guide plate 400 on the
reflection plate 125, and at least one optical sheet 121. The light
guide plate 123 is an optical fiber type light guide plate.
[0364] The reflection plate 125 is located below the light guide
plate 400, and reflects light coming out from the bottom surface of
the light guide plate 400 to the liquid crystal panel 110, and thus
brightness of light is improved.
[0365] The at least one optical sheet 121 may include a diffusion
sheet, and at least one light concentration sheet. The at least one
optical sheet 121 diffuses and/or concentrates light from the light
guide plate 400 to supply more uniform plane light to the liquid
crystal panel 110.
[0366] The non-polar or semi-polar LEDs 300 as light sources are
located at and faces the light incidence surface of the light guide
plate 400.
[0367] The non-polar or semi-polar LED 300 has a property of
emitting light polarized in a specific direction.
[0368] A specific linearly polarized light entering the light guide
plate 400 from the non-polar or semi-polar LED 300 travels in the
light guide plate 400 and evenly spreads over a large area of the
light guide plate 400, and thus a plane light is supplied to the
liquid crystal panel 110.
[0369] The light guide plate 400 is formed using a plurality of
optical fibers 410 which are arranged in parallel with each other
to form a plate.
[0370] As illustrated in FIG. 19B, the optical fiber 410 includes a
core 411 at a center portion, and a clad 413 enclosing an outer
surface of the core 411.
[0371] The clad 413 includes a light guide portion 413a, which has
a refractive index (n2) less than a refractive index (n1) of the
core 411 and in which a total internal reflection happens, and a
light emission portion 413b which has a refractive index (n3) equal
to or greater than the refractive index (n1) of the core 411 and
which emits an internal light to the outside.
[0372] The refractive index (n1) of the core 411, the refractive
index (n2) of the light guide portion 413a, and the refractive
index of the light emission portion 413b each have a range of about
1.2 to about 1.6 greater than a refractive index of an air.
[0373] In other words, in order that a linearly polarized light
from the LED 300 traveling in the core 411 with a total reflection
is emitted to the outside at a certain position, the clad 413 has a
refractive index at a predetermined position different from that at
other position. That is, the light emission portion 413b is formed
to have a refractive index different from other portion.
[0374] When a refractive index of the clad 413 is less than that of
the core 411, an internal light of the core 411 travels being
reflected inside the core 411. However, when a refractive index of
the clad 413 at a certain position is greater than that of the core
411, a condition for the total internal reflection at the position
is not met, a part of the light traveling in the core 411
externally escapes from the optical fiber 410.
[0375] In this regard, the light guide portion 413a and the light
emission portion 413b are configured to contact each other from an
inner side of the clad 413 to an outer side of the clad 413.
[0376] The optical fibers 410 as above are bound to each other to
form the optical fiber type light guide plate 400. Accordingly, a
backlight unit 160 can be configured to emit light at a
predetermined position on a length direction of the optical fiber
410.
[0377] In this embodiment, since the nanocapsule liquid crystal
layer 200 does not have an initial alignment to be optically
anisotropic, alignment of liquid crystal molecules may not be
required, and thus no alignment layer may be needed in the LCD 100,
and also, processes for forming an alignment layer such as rubbing
may not be needed.
[0378] Further, in case that the nanocapsules 230 are dispersed in
the buffer layer 210 made of, for example, liquid crystal, the
nanocapsule liquid crystal layer 200 may be formed, for example, by
a printing method, coating method, or dispensing method. In case
that the nanocapsules 230 are dispersed in the buffer layer 210
made in a film type, the nanocapsule liquid crystal layer 200 may
be formed, for example, by a lamination method. Accordingly, a
process of forming a gap between the first and second substrates
filled with the liquid crystal layer in the prior art can be
eliminated, and a process of forming the seal pattern in the prior
art can be eliminated.
[0379] Therefore, production efficiency can be improved.
[0380] Further, even when an external force such as a user's touch
is applied to the LCD of the embodiment, the liquid crystal
molecules 220 are in the nanocapsule 230 having a size less than
the wavelength of visible light, thus there is no influence of
visible light, and thus light leakage due to the external force can
be reduced or prevented.
[0381] Accordingly, in case that the LCD of the embodiment is
applied as a flexible display device, even when the external force
is applied to the LCD, because of the nanocapsule 230 having a size
less than the wavelength of visible light, light leakage due to the
external force can be prevented.
[0382] Particularly, since the flexible type LCD of the embodiment
includes the non-polar or semi-polar LED 300 emitting a
predetermined linearly polarized light, the linearly polarized
light from the backlight unit 160 is supplied to the liquid crystal
panel 110. Accordingly, one polarizing plate can be eliminated.
[0383] Thus, the LCD of the embodiment may not require the second
substrate (4 of FIG. 2) and one polarizing plate (20 of FIG. 2) in
the prior art, thus a total thickness of the liquid crystal panel
110 can be reduced, and thus the LCD can have lightweight and thin
profile and can be effectively applied as the flexible type display
device. Further, since the optical fiber type light guide plate 400
is used for the LCD, the backlight unit 160 of thin-profile and
high efficiency can be provided, and thus the flexible LCD can be
applied to a bendable or rollable display device.
[0384] Alternatively, the light guide plate (123 of one of FIGS.
17B to 17D) of one of the seventh to ninth embodiments may be an
optical fiber type light guide plate. Further, in the LCD of the
tenth or eleventh embodiment, the nanocapsule liquid crystal layer
200 may be located to face the backlight unit 160 like FIG. 17C or
FIG. 17D.
[0385] Further, the LCD of the tenth or eleventh embodiment may
employ the liquid crystal panel 110 and the backlight unit 160
modulized using a lamination process. In this process, an adhesive
is interposed between the liquid crystal panel 110 and the
backlight unit 120 to eliminate an air gap therebetween, and thus
loss of light due to the air gap can be prevented.
[0386] It will be apparent to those skilled in the art that various
modifications and variation can be made in the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *