U.S. patent application number 14/119821 was filed with the patent office on 2014-04-24 for optical member, display device including the same, method for manufacturing the same.
This patent application is currently assigned to LG INNOTEK CO., LTD.. The applicant listed for this patent is Sahng Jin Lee. Invention is credited to Sahng Jin Lee.
Application Number | 20140111968 14/119821 |
Document ID | / |
Family ID | 47217441 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140111968 |
Kind Code |
A1 |
Lee; Sahng Jin |
April 24, 2014 |
OPTICAL MEMBER, DISPLAY DEVICE INCLUDING THE SAME, METHOD FOR
MANUFACTURING THE SAME
Abstract
Disclosed are an optical sheet, a display device including the
same, and a method for manufacturing the same. The optical sheet
includes a host layer, a plurality of wavelength conversion
particles in the host layer, and a plurality of optical path change
particles in the host layer.
Inventors: |
Lee; Sahng Jin; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Sahng Jin |
Seoul |
|
KR |
|
|
Assignee: |
LG INNOTEK CO., LTD.
Seoul
KR
|
Family ID: |
47217441 |
Appl. No.: |
14/119821 |
Filed: |
December 7, 2011 |
PCT Filed: |
December 7, 2011 |
PCT NO: |
PCT/KR2011/009401 |
371 Date: |
November 22, 2013 |
Current U.S.
Class: |
362/84 ; 362/317;
977/774 |
Current CPC
Class: |
G02B 6/005 20130101;
G02F 2001/133614 20130101; G02F 1/133606 20130101; G02B 5/0294
20130101; G02B 5/0242 20130101; B82Y 20/00 20130101; G02B 6/0051
20130101; Y10S 977/774 20130101 |
Class at
Publication: |
362/84 ; 362/317;
977/774 |
International
Class: |
F21V 9/16 20060101
F21V009/16 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2011 |
KR |
10-2011-0049269 |
Claims
1.-18. (canceled)
19. An optical member comprising: a lower substrate; an upper
substrate; a host layer sandwiched between the upper and lower
substrates; a plurality of quantum dots in the host layer; a
plurality of optical path change particles in the host layer; a
first inorganic protective layer provided below the lower
substrate; and a second inorganic protective layer provided below
the upper substrate, wherein the first and second inorganic
protective layer comprise silicon oxide.
20. The optical member of claim 19, wherein the wavelength
conversion particles convert a wavelength of incident light.
21. The optical member of claim 19, wherein each wavelength
conversion particle has a diameter of about 1 nm to about 10 nm,
and each optical path change particle has a diameter of about 1
.mu.m to about 10 .mu.m.
22. The optical member of claim 19, wherein the host layer includes
silicon resin.
23. The optical member of claim 19, wherein a difference in a
refractive index between each optical path change particle and the
host layer is in a range of about 0.3 to about 1.5.
24. The optical member of claim 19, wherein each optical path
change particle includes an inorganic material.
25. The optical member of claim 19, wherein each optical path
change particle includes a metallic oxide.
26. The optical member of claim 25, wherein the optical path change
particle includes a material selected from the group consisting of
titanium oxide and aluminum oxide.
27. The optical member of claim 19, wherein the host layer includes
thermoplastic resin.
28. The optical member of claim 27, wherein the host layer includes
a material selected from the group consisting of polyacrylonitrile,
polyvinylidene chloride, and ethylene vinyl alcohol.
29. A display device comprising: an optical member including a
lower substrate, an upper substrate, a host layer, a plurality of
quantum dots in the host layer, a plurality of optical path change
particles in the host layer, a first inorganic protective layer
provided below the lower substrate, and a second inorganic
protective layer provided below the upper substrate, wherein the
first and second inorganic protective layer comprise silicon
oxide.
30. The display device of claim 29, further comprising: a light
source to output light to the optical member; and a display panel
provided above the optical member to receive light converted by the
optical member.
Description
TECHNICAL FIELD
[0001] The embodiment relates to an optical member, a display
device including the same, and a method for manufacturing the
same.
BACKGROUND ART
[0002] Recently, flat display devices, such as an LCD (liquid
crystal display), a PDP (plasma display panel) or an OLED (organic
light emitting diode), have been increasingly developed instead of
conventional CRTs (cathode ray tubes).
[0003] Among them, the LCD includes a liquid crystal display panel
having a thin film transistor substrate, a color filter substrate
and a liquid crystal injected between the thin film transistor
substrate and the color filter substrate. Since the liquid crystal
display panel is a non-emissive device, a backlight unit is
provided below the thin film transistor substrate to supply light.
Transmittance of the light emitted from the backlight unit is
adjusted according to the alignment state of the liquid
crystal.
[0004] The backlight unit is classified into an edge-illumination
type backlight unit and a direct-illumination type backlight unit
according to the position of a light source. According to the
edge-illumination type backlight unit, the light source is located
at a lateral side of a light guide plate.
[0005] The direct-illumination type backlight unit has been mainly
developed as the size of the LCD has become enlarged. According to
the direct-illumination type backlight unit, at least one light
source is located below the liquid crystal display panel to supply
the light over the whole area of the liquid crystal display
panel.
[0006] When comparing with the edge-illumination type backlight
unit, the direct-illumination type backlight unit can employ a
large number of light sources so that the high brightness can be
achieved. In contrast, the direct-illumination type backlight unit
must have thickness greater than thickness of the edge-illumination
type backlight unit in order to ensure brightness uniformity.
[0007] In order to solve the above problem, a quantum dot bar
having a plurality of quantum dots, which can convert blue light
into red light or green light when receiving the blue light, is
positioned in front of a blue LED that emits the blue light. Thus,
as the blue light is irradiated onto the quantum dot bar, the blue
light, the red light and the green light are mixed to each other by
the quantum dots distributed in the quantum dot bar and the mixed
light is incident into the light guide plate, thereby generating
white light.
[0008] If the white light is supplied to the light guide plate by
using the quantum dot bar, high color reproduction may be
realized.
[0009] The backlight unit may include an FPCB (flexible printed
circuit board) provided at one side of the blue LED, which emits
blue light, to supply signals and power to the LEDs and a bonding
member formed under the bottom surface of the FPCB.
[0010] The display device capable of displaying various images
using the white light supplied to the light guide plate through the
quantum dot bar as the blue light is emitted from the blue LED has
been extensively used.
[0011] A display device employing the quantum dots has been
disclosed in Korean Patent Unexamined Publication No.
10-2011-0068110.
DISCLOSURE OF INVENTION
Technical Problem
[0012] The embodiment provides an optical member, which can be
easily manufactured and represent improved optical performance, a
display device, and a method for manufacturing the same.
Solution to Problem
[0013] According to the embodiment, an optical member includes a
host layer, a plurality of wavelength conversion particles in the
host layer, and a plurality of optical path change particles in the
host layer.
[0014] According to the embodiment, a display apparatus includes
the optical member.
[0015] According to the embodiment, a method for manufacturing an
optical member includes providing a plurality of wavelength
conversion particles and a plurality of optical path change
particles, and forming a host layer surrounding the wavelength
conversion particles and the optical path change particles.
Advantageous Effects of Invention
[0016] As described above, since the optical member according to
the embodiment includes wavelength conversion particles and optical
path change particles, the wavelength of the incident light can be
converted, and the path of the incident light can be changed.
[0017] Therefore, the optical member according to the embodiment
has both a wavelength conversion function and a light diffusion
function. In other words, the optical member according to the
embodiment can act as both a wavelength conversion sheet and a
wavelength conversion diffusion sheet.
[0018] In addition, the path of the light passing through the
optical member according to the embodiment can be increased due to
the optical path change particles. Therefore, light incident onto
the optical member according to the embodiment can be effectively
changed by wavelength conversion particles.
[0019] In other words, due to the optical path change particles,
light can be effectively incident onto the wavelength conversion
particles and the utilization of the wavelength conversion
particles can be maximized. In addition, the wavelengths of a
greater amount of lights can be converted by a small number of
wavelength conversion particles, due to the combination of the
optical path change particles and the wavelength conversion
particles.
[0020] Therefore, the optical member according to the embodiment
can realize more improved color reproduction and more improved
brightness due to the combination of the optical path change
particles and the wavelength conversion particles even if a smaller
number of wavelength conversion particles may be used.
[0021] Accordingly, the optical member and the display device
according to the embodiment can be easily manufactured with
improved optical performance.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a perspective view showing a liquid crystal
display according to the embodiment;
[0023] FIG. 2 is a sectional view showing a wavelength conversion
diffusion sheet;
[0024] FIG. 3 is a view showing a procedure of displaying an image
by the liquid crystal display according to the embodiment;
[0025] FIG. 4 is a view showing a light traveling procedure within
a wavelength conversion diffusion sheet;
[0026] FIGS. 5 to 7 are sectional views showing a process of
manufacturing the wavelength conversion diffusion sheet according
to the embodiment;
[0027] FIGS. 8 and 9 are views showing the process of manufacturing
the wavelength conversion diffusion sheet through another method
according to the embodiment; and
[0028] FIG. 10 is a sectional view showing a wavelength conversion
diffusion sheet according to another embodiment.
MODE FOR THE INVENTION
[0029] In the description of the embodiments, it will be understood
that when a layer (or film), a region, a pattern, or a structure is
referred to as being "on" or "under" another substrate, another
layer (or film), another region, another pad, or another pattern,
it can be "directly", or"indirectly" on the other substrate, layer
(or film), region, pad, or pattern, or one or more intervening
layers may also be present. Such a position of the layer has been
described with reference to the drawings. The thickness and size of
each layer shown in the drawings may be exaggerated, omitted or
schematically drawn for the purpose of convenience or clarity. In
addition, the size of elements does not utterly reflect an actual
size.
[0030] FIG. 1 is a perspective view showing an LCD (Liquid Crystal
Display) according to the embodiment, and FIG. 2 is a sectional
view showing a wavelength conversion diffusion sheet. FIG. 3 is a
view showing a procedure of displaying an image by the LCD
according to the embodiment, and FIG. 4 is a view showing a light
traveling procedure within a wavelength conversion diffusion
sheet.
[0031] Referring to FIGS. 1 to 4, the LCD according to the
embodiment includes a backlight unit 10 and a liquid crystal panel
20.
[0032] The backlight unit 10 supplies light to the liquid crystal
panel 20. The backlight unit 10 serves as a surface light source so
that the light can be uniformly supplied to a bottom surface of the
liquid crystal panel 20.
[0033] The backlight unit 10 is disposed below the liquid crystal
panel 20. The backlight unit 10 includes a bottom cover 100, a
light guide plate 200, a reflective sheet 300, a plurality of light
emitting diodes 400, a printed circuit board 401, and a plurality
of optical sheets 500.
[0034] The upper portion of the bottom cover 100 is open. The
bottom cover 100 receives the light guide plate 200, the light
emitting diodes 400, the printed circuit board 401, the reflective
sheet 300, and the optical sheets 500 therein.
[0035] The light guide plate 200 is disposed in the bottom cover
100 and arranged on the reflective sheet 300. The light guide plate
200 guides the light upward by totally-reflecting, refracting and
scattering the light incident thereto from the light emitting
diodes 400.
[0036] The reflective sheet 300 is disposed under the light guide
plate 200. In more detail, the reflective sheet 300 is disposed
between the light guide plate 200 and the bottom surface of the
bottom cover 100. The reflective sheet 300 reflects the light
upward as the light is output downward from the bottom surface of
the light guide plate 200.
[0037] The light emitting diodes 400 serve as a light source for
generating the light. The light emitting diodes 400 are disposed at
one lateral side of the light guide plate 200. The light generated
from the light emitting diodes 400 is incident into the light guide
plate 200 through the lateral side of the light guide plate
200.
[0038] The light emitting diodes 400 may include a blue light
emitting diode generating the blue light or a UV light emitting
diode generating the UV light. In detail, the light emitting diodes
400 may emit the blue light having the wavelength band of about 430
nm to 470 nm or the UV light having the wavelength band of about
300 nm to 400 nm.
[0039] The light emitting diodes 400 are mounted on the printed
circuit board 401. The light emitting diodes 400 may be disposed
under the printed circuit board 401. The light emitting diodes 400
are driven by receiving a driving signal through the printed
circuit board 401.
[0040] The printed circuit board 401 is electrically connected to
the light emitting diodes 400. The printed circuit board 401 may
mount the light emitting diodes 400 thereon. The printed circuit
board 401 is disposed in the bottom cover 100.
[0041] The optical sheets 500 are disposed on the light guide plate
200. The optical sheets 500 supplies the light to the liquid
crystal panel 20 by changing or enhancing the optical property of
the light output from the top surface of the light guide plate
200.
[0042] The optical sheets 500 include a wavelength conversion
diffusion sheet 501, a first prism sheet 502 and a second prism
sheet 503.
[0043] The wavelength conversion diffusion sheet 501 is disposed on
the light guide plate 200. In addition, the wavelength conversion
diffusion sheet 501 is disposed below the liquid crystal panel 20.
In more detail, the wavelength conversion diffusion sheet 501 can
be disposed between the light guide plate 200 and the first prism
sheet 502.
[0044] The wavelength conversion diffusion sheet 501 is an optical
member to change or enhance the characteristic of light emitted
from the light emitting diodes 400. In other words, the wavelength
conversion diffusion sheet 501 is an optical member to change or
enhance the characteristic of light emitted from the light emitting
diodes 400, so that the light from the light emitting diodes 400 is
incident onto the liquid crystal panel 20.
[0045] The wavelength conversion diffusion sheet 501 may output the
incident light upward by changing the wavelength of the incident
light. In addition, the wavelength conversion diffusion sheet 501
may output the incident light upward by enhancing the uniformity of
the incident light.
[0046] For instance, if the light emitting diodes 400 are blue
light emitting diodes, the wavelength conversion diffusion sheet
501 converts the blue light output upward from the light guide
plate 200 into the green light and the red light. In detail, the
wavelength conversion diffusion sheet 501 converts a part of the
blue light into the green light having the wavelength in the range
of about 520 nm to about 560 nm, and a part of the blue light into
the red light having the wavelength in the range of about 630 nm to
about 660 nm.
[0047] In addition, if the light emitting diodes 400 are UV light
emitting diodes, the wavelength conversion diffusion sheet 501
converts the UV light output from the top surface of the light
guide plate 200 into the blue light, the green light and the red
light. In detail, the wavelength conversion diffusion sheet 501
converts a part of the UV light into the blue light having the
wavelength in the range of about 430 nm to about 470 nm, a part of
the UV light into the green light having the wavelength in the
range of about 520 nm to about 560 nm, and a part of the UV light
into the red light having the wavelength in the range of about 630
nm to about 660 nm.
[0048] Therefore, the white light may be generated by the light
passing through the wavelength conversion diffusion sheet 501
without being converted and the lights converted by the wavelength
conversion diffusion sheet 501. In detail, the white light can be
incident into the liquid crystal panel 20 through the combination
of the blue light, the green light and the red right.
[0049] In this case, the white light output from the wavelength
conversion diffusion sheet 501 may have more enhanced uniformity
than that of the blue light or the UV light incident onto the
wavelength conversion diffusion sheet 501.
[0050] As shown in FIG. 2, the wavelength conversion diffusion
sheet 501 includes a host layer 531, a plurality of wavelength
conversion particles 532, and a plurality of optical path change
particles 533. The wavelength conversion diffusion sheet 501 may
have a single layer structure.
[0051] The host layer 531 contains the wavelength conversion
particles 532 and the optical path change particles 533. In other
words, the wavelength conversion particles 532 and the optical path
change particles 533 are uniformly distributed in the host layer
531.
[0052] The host layer 531 is transparent and has a high sealing
property. In more detail, the host layer 531 may have a low oxygen
transmission rate.
[0053] In addition, the host layer 531 may include high-density
polymers. For example, the host layer 531 may include polymers
having a density of about 1.0 g/ml to about 2.0 g/ml. The host
layer 531 may include polymer having a refractive index in the
range of about 1.4 to about 1.6.
[0054] The host layer 531 may include epoxy resin, acrylic resin,
polyimide resin, or silicon resin. In more detail, the host layer
531 may include silicon resin.
[0055] The silicon resin may have a framework structure having a
siloxane (--SI--O--) bond. In addition, a methyl group, a phenyl
group, or a hydroxyl group may be added to the siloxane
framework.
[0056] For example, the silicon resin may be expressed as following
chemical formula 1.
##STR00001##
[0057] In chemical formula 1, each of R1, R2, R3, and R4 can be
independently selected from the group consisting of hydrogen,
halogen, alkyl, aryl, cyclo alkyl, and hetero aryl groups.
[0058] In addition, the host layer 531 may further include a cross
linking agent. The sealing property of the host layer 531 may be
more enhanced by the cross linking agent. About 20 wt % to about 25
wt % of the cross linking agent may be contained in the host layer
531.
[0059] The cross linking agent may include one selected from the
group consisting of 1,6-hexanediol diacrylate, dipropylene glycol
diacrylate, neopentyl glycol diacrylate, trimethylolpropane
triacrylate, ethoxylated trimethylolpropane triacrylate,
trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate,
dipentaerylthritol hexaacrylate, vinyltriethoxysilane,
vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy)silane, and
vinylmethyldimethoxysilane.
[0060] In addition, the host layer 531 may include a metal salt. In
more detail, the host layer 531 may further include a platinum
salt. The sealing property of the host layer 531, in more detail,
the oxygen blocking characteristic of the host layer 531 can be
improved by the platinum salt. The host layer 531 may contain about
0.001 wt % to about 0.01 wt % of the platinum salt.
[0061] The platinum salt may include platinum amine, platinum
chloride, or platinum ammonium.
[0062] In addition, the host layer 531 may include a thermoplastic
resin. In more detail, the host layer 531 is transparent, and may
include a thermoplastic resin representing high air tightness.
[0063] For example, the host layer 531 includes a polymer or a
copolymer including a monomer expressed as following chemical
formula 2. In more detail, the host layer 531 may include the
polymer or the copolymer.
##STR00002##
[0064] In this case, at least one of the R1, R2, R3, and R4 is a
chlorine group, a nitrile group, or a hydroxyl group. A functional
group among the R1, R2, R3, and R4, which is not selected as the
chlorine group, the nitrile group, or the hydroxyl group, may be
selected from the group consisting of hydrogen, a substituted alkyl
group, a non-substituted alkyl group, a substituted aryl group, a
non-substituted aryl group, a substituted alkoxy group, a
non-substituted alkoxy group, a substituted heteroaryl group, and a
non-substituted heteroaryl group. In this case, the n may be in the
range of about 1 to about 10000.
[0065] According to one embodiment, at least one of the R1, R2, R3,
and R4 is a chlorine group, a nitrile group, or a hydroxyl group,
and a functional group of the R1, R2, R3, and R4, which is not
selected as the chlorine group, the nitrile group, or the hydroxyl
group, may be hydrogen.
[0066] According to one embodiment, the R4 is a nitrile group, and
each of the R1, R2, and R3 may be selected from the group
consisting of hydrogen, a substituted alkyl group, a
non-substituted alkyl group, a substituted aryl group, a
non-substituted aryl group, a substituted alkoxy group, a
non-substituted alkoxy group, a substituted heteroaryl group, and a
non-substituted heteroaryl group.
[0067] According to one embodiment, the R4 and R4 are chlorine
groups, and each of the R1 and R2 may be selected from the group
consisting of hydrogen, a substituted alkyl group, a
non-substituted alkyl group, a substituted aryl group, a
non-substituted aryl group, a substituted alkoxy group, a
non-substituted alkoxy group, a substituted heteroaryl group, and a
non-substituted heteroaryl group.
[0068] According to one embodiment, the R4 is a hydroxyl group and
each of the R1, R2, and R3 may be selected from the group
consisting of hydrogen, a substituted alkyl group, a
non-substituted alkyl group, a substituted aryl group, a
non-substituted aryl group, a substituted alkoxy group, a
non-substituted alkoxy group, a substituted heteroaryl group, and a
non-substituted heteroaryl group.
[0069] According to the embodiment, the host layer 531 may include
a polymer or a copolymer including a monomer expressed as following
chemical formula 3.
##STR00003##
[0070] In this case, the n may be range of 1 to 10000.
[0071] In more detail, the polymer or the copolymer may include
poly-acrylic-nitrile (PAN).
[0072] According to one embodiment, the host layer 531 may include
a polymer or a copolymer including a monomer expressed as following
chemical formula 4.
##STR00004##
[0073] In this case, the n may be in the range of 1 to 10000.
[0074] In more detail, the polymer or the copolymer may include
polyvinyliden chloride (PVDC).
[0075] According to one embodiment, the host layer 531 may include
a polymer or a copolymer expressed as following chemical formula
5.
##STR00005##
[0076] In this case, the n may be in the range of 1 to 10000, and
the m may be in the range of 1 to 10000.
[0077] In more detail, the polymer or the copolymer may include
ethylene vinylalcohol (EVOH).
[0078] The host layer 531 is transparent, and has a low moisture
transmission rate and/or a low oxygen transmission rate. For
example, the moisture transmission rate of the host layer 531 may
be in the range of about 0.05(cc mm/100 in.sup.2 24 hr atm) to
about 0.9(cc mm/100 in.sup.2 24 hr atm) at the temperature of about
25.degree. C. under the humidity condition of about 65% .
[0079] Since the host layer 531 represents high moisture and oxygen
blocking characteristics, the wavelength conversion particles 532
can be effectively protected from external oxygen and/or external
moisture.
[0080] The wavelength conversion particles 532 are provided in the
host layer 531. The wavelength conversion particles 532 are
uniformly distributed in the host layer 531.
[0081] The wavelength conversion particles 532 convert the
wavelength of the light emitted from the light emitting diodes 400.
In detail, the wavelength conversion particles 532 receive light
emitted from the light emitting diodes 400 to convert the
wavelength of the incident light. For instance, the wavelength
conversion particles 532 may convert the blue light emitted from
the light emitting diodes 400 into the green light and the red
light. That is, a part of the wavelength conversion particles 532
may convert the blue light into the green light having the
wavelength in the range of about 520 nm to about 560 nm and a part
of the wavelength conversion particles 532 may convert the blue
light into the red light having the wavelength in the range of
about 630 nm to about 660 nm.
[0082] In addition, the wavelength conversion particles 532 may
convert the UV light emitted from the light emitting diodes 400
into the blue light, the green light and the red light. That is, a
part of the wavelength conversion particles 532 may convert the UV
light into the blue light having the wavelength in the range of
about 430 nm to about 470 nm, and a part of the wavelength
conversion particles 532 may convert the UV light into the green
light having the wavelength in the range of about 520 nm to about
560 nm. Further, a part of the wavelength conversion particles 532
converts the UV light into the red light having the wavelength in
the range of about 630 nm to about 660 nm.
[0083] In other words, if the light emitting diodes 400 are blue
light emitting diodes that emit the blue light, the wavelength
conversion particles 532 capable of converting the blue light into
the green light and the red light may be employed. In addition, if
the light emitting diodes 400 are UV light emitting diodes that
emit the UV light, the wavelength conversion particles 532 capable
of converting the UV light into the blue light, the green light and
the red light may be employed.
[0084] The wavelength conversion particles 532 may include a
plurality of quantum dots. The quantum dots may include core
nano-crystals and shell nano-crystals surrounding the core
nano-crystals. In addition, the quantum dots may include organic
ligands bonded to the shell nano-crystals. In addition, the quantum
dots may include an organic coating layer surrounding the shell
nano-crystals.
[0085] The shell nano-crystals may be prepared as at least two
layers. The shell nano-crystals are formed on the surface of the
core nano-crystals. The quantum dots lengthen the wavelength of the
light incident into the core nano-crystals by using the shell
nano-crystals forming a shell layer, thereby improving the light
efficiency.
[0086] The quantum dots may include at least one of a group-II
compound semiconductor, a group-III compound semiconductor, a
group-V compound semiconductor, and a group-VI compound
semiconductor. In more detail, the core nano-crystals may include
CdSe, InGaP, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. In addition,
the shell nano-crystals may include CuZnS, CdSe, CdTe, CdS, ZnSe,
ZnTe, ZnS, HgTe or HgS. The quantum dot may have a diameter of
about 1 nm to about 10 nm.
[0087] The wavelength of the light emitted from the quantum dots
can be adjusted according to the size of the quantum dot or the
molar ratio between the molecular cluster compound and the
nano-particle precursor in the synthesis process. The organic
ligand may include pyridine, mercapto alcohol, thiol, phosphine and
phosphine oxide. The organic ligand may stabilize the unstable
quantum dots after the synthesis process. Dangling bonds may be
formed at the valence band and the quantum dots may be unstable due
to the dangling bonds. However, since one end of the organic ligand
is the non-bonding state, one end of the organic ligand is bonded
with the dangling bonds, thereby stabilizing the quantum dots.
[0088] In particular, if the size of the quantum dot is smaller
than the Bohr radius of an exciton, which consists of an electron
and a hole excited by light and electricity, the quantum
confinement effect may occur, so that the quantum dot may have the
discrete energy level. Thus, the size of the energy gap is changed.
In addition, the charges are confined within the quantum dot, so
that the light emitting efficiency can be improved.
[0089] Different from general fluorescent pigments, the fluorescent
wavelength of the quantum dot may vary depending on the size of the
particles. In detail, the light has the shorter wavelength as the
size of the particle is reduced, so that the fluorescent light
having the required wavelength band of visible ray can be generated
by adjusting the size of the particles. In addition, the quantum
dot represents the extinction coefficient which is 100 to 1000
times higher than that of the general fluorescent pigment and has
the superior quantum yield as compared with the general fluorescent
pigment, so that strong fluorescent light can be generated.
[0090] The quantum dots can be synthesized through the chemical wet
scheme. The chemical wet scheme is to grow the particles by
immersing the precursor material in the organic solvent. According
to the chemical wet scheme, the quantum dots can be
synthesized.
[0091] The optical path change particles 533 are disposed in the
host layer 531. The optical path change particles 533 are inserted
into the host layer 531. The optical path change particles 533 are
uniformly distributed in the host layer 531. The optical path
change particles 533 are interposed between the wavelength
conversion particles 532.
[0092] In addition, a part of the optical path change particles 533
may be inserted into the host layer 531. In other words, the part
of the optical path change particles 533 may be exposed out of the
host layer 531.
[0093] The optical path change particles 533 may be transparent.
The optical path change particles 533 may have a lower refractive
index or a higher refractive index with respect to the host layer
531. The difference in the refractive index between the optical
path change particles 533 and the host layer 531 may be in the
range of about 0.3 to about 1.5. In more detail, the difference in
the refractive index between the optical path change particles 533
and the host layer 531 may be in the range of about 0.4 to about
1.
[0094] The optical path change particles 533 can change the path of
the incident light due to the refractive index difference. For
example, the optical path change particles 533 can change the path
of the incident light due to the reflection and/or the refraction.
Accordingly, the optical path change particles 533 can scatter or
diffuse the incident light.
[0095] For instance, the optical path change particles 533 may
include polymethyl methacrylate (PMMA), polycarbonate (PC), or
cyclic olefin polymer.
[0096] In addition, the optical path change particles 533 may
include an inorganic material.
[0097] In more detail, the optical path change particles 533 may
include a transparent inorganic material. The optical path change
particles 533 may include titanium oxide or aluminum oxide.
[0098] If the optical path change particles 533 include inorganic
materials, the airtightness of the host layer 531 can be improved.
Accordingly, the wavelength conversion particles 532 can be
effectively protected from external moisture and/or external oxygen
by the optical path change particles 533 and the host layer
531.
[0099] The optical path change particles 533 may have various
shapes. In detail, the optical path change particles 533 may have
various shapes such as a spherical shape, a polyhedral shape, a
cylindrical shape, or a polyprism shape.
[0100] The optical path change particles 533 are larger than the
wavelength conversion particles 532. In more detail, the optical
path change particles 533 may be 100 times larger than the
wavelength conversion particles 532. For instance, the optical path
change particles 533 may have a diameter in the range of about 1
.mu.m to about 10 .mu.m.
[0101] The first prism sheet 502 is provided on the wavelength
conversion diffusion sheet 501. The second prism sheet 503 is
formed on the first prism sheet 502. The first and second prism
sheets 502 and 503 may enhance the linearity of light passing
through the first and second prism sheets 502 and 503.
[0102] The liquid crystal panel 20 is disposed on the optical
sheets 500. In addition, the liquid crystal panel 20 is disposed on
the panel guide 23. The liquid crystal panel 20 is guided by the
panel guide 23.
[0103] The liquid crystal panel 20 displays images by adjusting
intensity of light passing through the liquid crystal panel 20. In
detail, the liquid crystal panel 20 is a display panel for
displaying the images by using the light emitted from the backlight
unit 10. The liquid crystal panel 20 includes a TFT substrate 21, a
color filter substrate 22 and a liquid crystal layer interposed
between the two substrates. In addition, the liquid crystal panel
20 includes polarizing filters.
[0104] Hereinafter, the TFT substrate 21 and the color filter
substrate 22 will be described in detail although it is not shown
in the drawings in detail. The TFT substrate 21 includes a
plurality of gate lines crossing a plurality of data lines to form
pixels and a thin film transistor (TFT) is provided at each cross
section such that the thin film transistor TFT can be connected to
a pixel electrode of the pixel in one-to-one correspondence. The
color filter substrate 22 includes color filters having R, G and B
colors corresponding to the pixels, a black matrix covering the
gate lines, data lines and thin film transistors within the limit
of the color filters, and a common electrode covering the above
elements.
[0105] A driving PCB 25 is provided at an outer peripheral portion
of the LCD panel 210 to supply driving signals to the gate lines
and data lines.
[0106] The driving PCB 25 is electrically connected to the liquid
crystal panel 20 by a COF (chip on film) 24. The COF 24 may be
replaced with a TCP (tape carrier package).
[0107] Since the wavelength conversion diffusion sheet 501 includes
the wavelength conversion particles 532 and the optical path change
particles 533, the wavelength of the incident light is changed
while changing the path of the incident light.
[0108] Therefore, the wavelength conversion diffusion sheet 501 can
perform both of a wavelength conversion function and a light
diffusion function. In other words, although the wavelength
conversion diffusion sheet 501 is made of one sheet, the wavelength
conversion diffusion sheet 501 can act as both the wavelength
conversion sheet and the light diffusion sheet.
[0109] As shown in FIG. 3, if the light emitting diodes 400 include
blue light emitting diodes, the blue light emitted from the light
emitting diodes 400 are output upward through the light guide plate
200. A part of the blue light emitted from the light guide plate
200 can be transmitted. A part of the blue light can converted into
green light to be output upward, and a part of the blue light can
converted into red light to be output upward.
[0110] In this case, as shown in FIG. 4, the path of light passing
through the wavelength conversion diffusion sheet 501 can be
increased due to the optical path change particles 533. Therefore,
light incident onto the wavelength conversion diffusion sheet 501
can be effectively converted by the wavelength conversion particles
532.
[0111] In other words, the path of the light incident onto the
wavelength conversion diffusion sheet 501 may be changed in a
substantially horizontal direction by the optical path change
particles 533. As described above, the light having the path
changed in the substantially horizontal direction may be more
effectively incident onto the wavelength conversion particles 532.
Therefore, even if the wavelength conversion diffusion sheet 501
contains a small number of wavelength conversion particles 532, the
wavelength conversion diffusion sheet 501 can effectively change
the wavelength of the incident light.
[0112] In other words, light can be effectively incident onto the
wavelength conversion particles 532 due to the optical path change
particles 533, so that the utilization of the wavelength conversion
particles 532 can be maximized. A small number of wavelength
conversion particles 532 can convert a greater amount of light
wavelengths due to the combination of the optical path change
particles 533 and the wavelength conversion particles 532.
[0113] Therefore, the wavelength conversion diffusion sheet 501 can
represent more improved color reproduction and more improved
brightness with a small number of wavelength conversion particles
532 due to the combination of the optical path change particles 533
and the wavelength conversion particles 532.
[0114] Therefore, the LCD according to the embodiment can be easily
manufactured while representing improved optical performance.
[0115] In addition, the host layer 531 represents the high sealing
property. Therefore, the wavelength conversion particles 532
provided in the host layer 531 can be effectively protected from
external chemical penetration, such as moisture and oxygen.
[0116] Therefore, the wavelength conversion diffusion sheet 501 may
have high endurance and reliability.
[0117] FIGS. 5 to 7 are sectional views showing a process of
manufacturing the wavelength conversion diffusion sheet according
to the embodiment. FIGS. 8 and 9 are views showing the process of
manufacturing the wavelength conversion diffusion sheet through
another method according to the embodiment. In the present
description about the method for manufacturing the wavelength
conversion diffusion sheet, the previous description about the
wavelength conversion diffusion sheet will be incorporated by
reference. In other words, the previous description about the
wavelength conversion diffusion sheet can be essentially associated
with the present description about the method for manufacturing the
wavelength conversion diffusion sheet.
[0118] Referring to FIG. 5, the wavelength conversion particles 532
and the optical path change particles 533 are uniformly mixed in a
resin composition 534. The resin composition 534 is transparent.
The resin composition 534 may have a light curing
characteristic.
[0119] The resin composition 534 may include epoxy resin, acrylic
resin, polyamic acid, bisphenol-A resin, or silicon resin. In
addition, the resin composition 534 may include acrylate monomer,
or siloxane monomer.
[0120] In addition, the resin composition 534 may include a light
curing initiator. The light curing initiator may be selected from
the group consisting of .alpha.-hydroxyketone, phenylglyoxylate,
benzildimethyl ketal, .alpha.-aminoketone, mono acyl phosphine, bis
acyl phosphine, 2,2-dimethoxy-2-phenylacetophenone, and the
compound thereof.
[0121] In addition, the resin composition 534 may include the cross
linking agent. In addition, the resin composition 534 may further
include an addition agent to improve the sealing property. The
metal salt such as the platinum salt may be added to the resin
composition 534 as the addition agent.
[0122] Thereafter, the resin composition 534 is uniformly coated on
the top surface of the sacrificial substrate 30. The resin
composition 534 may be coated through a spin coating process, a
slit coating process, or a spray coating process.
[0123] Referring to FIG. 6, UV ray is irradiated into the resin
composition 534 coated on the sacrificial surface 30. Accordingly,
the resin composition 534 is cured, and the wavelength conversion
diffusion sheet 501 is formed on the sacrificial substrate 30.
[0124] In addition to the curing process by UV ray, the resin
composition 534 may be cured by heat.
[0125] Referring to FIG. 7, the sacrificial substrate 30 is removed
from the wavelength conversion diffusion sheet 501. The wavelength
conversion diffusion sheet 501 may be adapted to a backlight unit
10.
[0126] When the host layer 531 includes thermoplastic resin, the
wavelength conversion diffusion sheet 501 may be formed through the
following processes.
[0127] Referring to FIG. 8, a polymer or a copolymer to be
contained in the host layer 531 is fabricated (step S10). The
polymer or the copolymer may be formed by polymerizing or
copolymerizing at least one kind of monomers.
[0128] For example, polyvinylidene chloride may be formed by
polymerizing a monomer such as vinylidene chloride through
suspension polymerization. In addition, the polyvinylidene chloride
may be formed by copolymerizing vinylidene chloride and vinyl
chloride. In this case, about 75% to about 90% of vinylidene
chloride may be copolymerized with about 25% to about 10% of vinyl
chloride.
[0129] For example, polyacrylionitrille may be formed by
radial-polymerizing monomers such as acrylionitrille. In addition,
the polyacrylionitrille may be formed by copolymerizing
acrylonitrile with monomers such as acrylic acid, esther acrylate,
styrene, or butadiene. In addition, about 50% to about 95% of the
acrylionitrille can be copolymerized.
[0130] For example, ethylene vinylalcohol may be formed by
co-polymerizing monomers such as ethylene and vinyl acetate. In
other words, the ethylene and the vinyl acetate are copolymerized
and saponified under high pressure. Thereafter, over alkali is
neutralized.
[0131] The polymer or the copolymer may be softened or melted by
heat (step S20).
[0132] The wavelength conversion particles 532 and the optical path
change particles 533 are uniformly distributed into the softened or
melted polymer or copolymer (step S30), so that resin composition
can be formed.
[0133] The resin composition is injection-molded (step S40), so
that the wavelength conversion diffusion sheet 501 can be
formed.
[0134] In addition, referring to FIG. 9, the wavelength conversion
diffusion sheet 501 may be formed through the following method.
[0135] First, monomers, the wavelength conversion particles 532 and
the optical path change particles 533 are uniformly mixed with each
other (step S11).
[0136] Thereafter, the monomer is polymerized or copolymerized,
thereby forming a polymer or a copolymer having the wavelength
conversion particles 532 and the optical path change particles 533
uniformly distributed therein (step S21).
[0137] Thereafter, the polymer or the copolymer is injection-molded
(step S31), so that the wavelength conversion diffusion sheet 501
can be formed.
[0138] FIG. 8 is a sectional view showing a wavelength conversion
diffusion sheet according to another embodiment. In the present
description about the wavelength conversion diffusion sheet, the
description about the wavelength conversion diffusion sheet
according to the previous embodiments will be incorporated by
reference. In other words, the description about the wavelength
conversion diffusion sheet according to the previous embodiments
can be essentially associated with the present description about
the wavelength conversion diffusion sheet except for modified parts
of the wavelength conversion diffusion sheet.
[0139] Referring to FIG. 8, the wavelength conversion diffusion
sheet 504 includes a lower substrate 510, an upper substrate 520, a
wavelength conversion layer 530, a first inorganic protective layer
540, and a second inorganic protective layer 550.
[0140] The lower substrate 510 is provided under the wavelength
conversion layer 530. The lower substrate 510 may be transparent
and flexible. The lower substrate 510 may adhere to a bottom
surface of the wavelength conversion layer 530.
[0141] The lower substrate 510 may include a transparent polymer,
such as polyethyleneterephthalate (PET).
[0142] The upper substrate 520 is disposed on the wavelength
conversion layer 530. The upper substrate 520 may be transparent
and flexible. The upper substrate 520 may adhere to the top surface
of the wavelength conversion layer 530.
[0143] The upper substrate 520 may include a transparent polymer
such as polyethyleneterephthalate (PET).
[0144] The wavelength conversion layer 530 is sandwiched between
the upper and lower substrates 520 and 510. The upper and lower
substrates 520 and 510 support the wavelength conversion layer 530.
The upper and lower substrates 520 and 510 protect the wavelength
conversion layer 530 from external physical impact.
[0145] In addition, the upper and lower substrates 520 and 510 have
a low oxygen transmission rate and low moisture permeability. Thus,
the upper and lower substrates 520 and 510 can protect the
wavelength conversion layer 530 from external chemical penetration,
such as oxygen and/or moisture.
[0146] The wavelength conversion layer 530 may have the same
components as those of the wavelength conversion diffusion sheet
501 of a single layer according to the prior embodiment. In other
words, the wavelength conversion layer 530 includes the host layer
531, a plurality of wavelength conversion particles 532, and a
plurality of optical path change particles 533.
[0147] The first inorganic protective layer 540 is provided below
the lower substrate 510. The first inorganic protective layer 540
may be coated on the bottom surface of the lower substrate 510.
[0148] The refractive index of the first inorganic protective layer
530 may have a refractive index lower than that of the lower
substrate 510. The first inorganic protective layer 540 may include
silicon oxide.
[0149] The second inorganic protective layer 550 is provided on the
upper substrate 520. The second inorganic protective layer 550 may
be coated on the top surface of the upper substrate 520.
[0150] The refractive index of the second inorganic protective
layer 550 may be lower than the refractive index of the upper
substrate 520. The second inorganic protective layer 550 may
include silicon oxide (Si.sub.xO.sub.y).
[0151] The wavelength conversion layer 530 is sandwiched between
the lower and upper substrates 510 and 520, and the first and
second inorganic protective layers 540 and 550. Therefore, the
lower and upper substrates 510 and 520, and the first and second
inorganic protective layers 540 and 550 protect the wavelength
conversion particles 532 from chemical penetration such as external
moisture and/or oxygen.
[0152] Therefore, the wavelength conversion diffusion sheet 501
according to the present embodiment can represent high endurance
and high reliability.
[0153] Any reference in this specification to "one embodiment", "an
embodiment", "example embodiment", etc., means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
invention. The appearances of such phrases in various places in the
specification are not necessarily all referring to the same
embodiment. Further, when a particular feature, structure, or
characteristic is described in connection with any embodiment, it
is submitted that it is within the purview of one skilled in the
art to effects such feature, structure, or characteristic in
connection with other ones of the embodiments.
[0154] Although embodiments have been described with reference to a
number of illustrative embodiments thereof, it should be understood
that numerous other modifications and embodiments can be devised by
those skilled in the art that will fall within the spirit and scope
of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts
and/or arrangements of the subject combination arrangement within
the scope of the disclosure, the drawings and the appended claims.
In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to
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