U.S. patent application number 14/369993 was filed with the patent office on 2015-09-03 for backlight unit.
The applicant listed for this patent is Seoul Semiconductor Co., Ltd.. Invention is credited to Young Jun Song.
Application Number | 20150247965 14/369993 |
Document ID | / |
Family ID | 50776289 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150247965 |
Kind Code |
A1 |
Song; Young Jun |
September 3, 2015 |
BACKLIGHT UNIT
Abstract
A backlight unit includes: a light guide plate of an entirely
flat structure; a light emitting element disposed on at least one
side of the light guide plate; a first reflection part disposed
under the light guide plate and having one side thereof extended to
a region where the light emitting element is positioned; a second
reflection part disposed on the light emitting element; and a
housing for accommodating the light guide plate, the light emitting
element, and the first and second reflection parts, wherein the
housing has a second side which is vertically extended upwards with
respect to a first side which defines a lateral cross section of
the housing in which the light emitting element is accommodated as
the lower side, and a third side which is vertically extended
inwards with respect to the second side.
Inventors: |
Song; Young Jun; (Ansan-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seoul Semiconductor Co., Ltd. |
Ansan-si |
|
KR |
|
|
Family ID: |
50776289 |
Appl. No.: |
14/369993 |
Filed: |
November 15, 2013 |
PCT Filed: |
November 15, 2013 |
PCT NO: |
PCT/KR13/10425 |
371 Date: |
June 30, 2014 |
Current U.S.
Class: |
362/606 ;
362/609; 362/612 |
Current CPC
Class: |
G02B 6/0031 20130101;
H01L 33/505 20130101; G02B 6/009 20130101; G02B 6/005 20130101;
G02F 1/133617 20130101; H01L 33/508 20130101; G02B 6/0088 20130101;
G02B 6/0091 20130101; G02B 6/0083 20130101; G02B 6/0073 20130101;
G02B 6/0055 20130101 |
International
Class: |
F21V 8/00 20060101
F21V008/00; H01L 33/50 20060101 H01L033/50 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2012 |
KR |
10-2012-0131685 |
Claims
1. A backlight unit comprising: a light guide plate having an
overall flat structure; a light emitting device disposed on at
least one side of the light guide plate; a first reflector disposed
under the light guide plate and having one side extending to an
area in which the light emitting device is disposed; a second
reflector disposed on the light emitting device; and a housing
receiving the light guide plate, the light emitting device, and the
first and second reflectors, wherein the housing has a side portion
on which the light emitting device is received, the side portion
having a cross-section including a first side defined as a lower
surface of the housing, a second side vertically extending from the
first side in an upper direction of the housing and a third side
vertically extending from the second side in an inner direction of
the housing, and wherein the light emitting device comprises a
flip-chip type light emitting diode chip and a wavelength
conversion layer covering an upper surface and both side surfaces
of the light emitting diode chip.
2. The backlight unit of claim 1, further comprising: a circuit
board disposed on the second side within the housing.
3. The backlight unit of claim 2, wherein the circuit board has one
surface facing the second side within the housing, and the other
surface on which the light emitting device is mounted.
4. The backlight unit of claim 3, wherein the first reflector has
an upper surface facing a lower surface of the light guide plate
and one side surface of the light emitting device, and a distal end
facing a portion of the other surface of the circuit board.
5. The backlight unit of claim 2, wherein the second reflector has
a portion extending to a position between the second side and the
circuit board.
6. The backlight unit of claim 2, wherein the second reflector has
a portion of an upper surface contacting a portion of a lower
surface of the third side, a portion of a lower surface contacting
a portion of the circuit board, and another portion of the lower
surface contacting a portion of an upper surface of the light guide
plate.
7. The backlight unit of claim 1, wherein the wavelength conversion
layer comprises a first layer covering the upper surface of the
light emitting diode chip and a second layer covering both side
surfaces of the light emitting diode chip, the first layer having a
higher thickness than the second layer.
8. The backlight unit of claim 2, further comprising: optical
sheets disposed on the light guide plate; and a light shielding
tape disposed parallel to the third side to cover edges of the
optical sheets in order to secure the optical sheets while
preventing light leakage.
9. A backlight unit comprising: a light guide plate having an
overall flat structure; a light emitting device disposed on at
least one side of the light guide plate; and a housing receiving
the light guide plate and the light emitting device, and having a
side portion, on which the light emitting device is received,
having a cross section comprising a second side vertically
extending in an upper direction based on a first side defined as a
lower side, and a third side vertically extending in an inner
direction based on the second side, wherein the light emitting
device comprises a flip-chip type light emitting diode chip and a
wavelength conversion layer covering an upper surface and both side
surfaces of the light emitting diode chip, wherein the wavelength
conversion layer comprises a first layer covering the upper surface
of the light emitting diode chip and a second layer covering both
side surfaces of the light emitting diode chip, the first layer
having a higher thickness than the second layer.
10. The backlight unit of claim 9, further comprising: a circuit
board disposed on the second side within the housing.
11. The backlight unit of claim 9, further comprising: a first
reflector disposed under the light guide plate and having one side
extending to an area in which the light emitting device is
disposed.
12. The backlight unit of claim 11, further comprising: a circuit
board disposed on the second side within the housing, wherein the
first reflector has an upper surface facing a lower surface of the
light guide plate and one side surface of the light emitting
device, and a distal end facing a portion of the other surface of
the circuit board.
13. The backlight unit of claim 12, further comprising: a second
reflector disposed on a portion of an upper surface of the light
guide plate, wherein the second reflector has a portion extending
to a position between the second side and the circuit board.
14. The backlight unit of claim 13, wherein the second reflector
has a portion of an upper surface contacting a lower surface of the
third side, a portion of a lower surface contacting a portion of
the circuit board, and another portion of the lower surface
contacting a portion of an upper surface of the light guide
plate.
15. The backlight unit of claim 9, further comprising: optical
sheets disposed on the light guide plate; and a light shielding
tape disposed parallel to the third side to cover edges of the
optical sheets in order to secure the optical sheets while
preventing light leakage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the National Stage of International
Application No. PCT/KR2013/010425, filed on Nov. 15, 2013, and
claims priority from and the benefit of Korean Patent Application
No. 10-2012-0131685, filed on Nov. 20, 2012, which are hereby
incorporated by reference for all purposes as if fully set forth
herein.
BACKGROUND
[0002] 1. Field
[0003] The present invention relates to a backlight unit, and more
particularly, to a backlight unit capable of minimizing a non-light
emitting region at an edge thereof while realizing a slim
structure.
[0004] 2. Discussion of the Background
[0005] General backlight units are broadly used for liquid crystal
displays or surface lighting.
[0006] Backlight units of liquid crystal displays can be classified
into direct type and edge type backlight units according to
locations of light emitting devices.
[0007] The direct type backlight units have been mainly developed
along with production of large-size liquid crystal displays having
a size of 20 inches or more, and include a plurality of light
sources under a diffusive plate to directly emit light towards a
front side of a liquid crystal display pane. The direct type
backlight units are mainly used in large-screen liquid crystal
displays requiring high brightness due to higher light use
efficiency than the edge type backlight units.
[0008] The edge type backlight units are mainly applied to
relatively small liquid crystal displays such as monitors of laptop
computers and desktop computers. Such an edge type backlight unit
has good uniformity of light and long lifespan, and is advantageous
in thickness reduction of a liquid crystal display.
[0009] FIG. 1 is a schematic sectional view of a backlight unit of
a general small liquid crystal display.
[0010] Referring to FIG. 1, a backlight unit 100 of a general small
liquid crystal display includes a housing 170, which is open at an
upper side thereof and receives a reflective sheet 160, a light
guide plate 150 and optical sheets 130 therein; a circuit board
111, and a light emitting device 110, which are disposed at one
side of the housing 170.
[0011] The backlight unit 100 constitutes one module by attaching a
light shielding tape 190 to an upper surface of the circuit board
111 and to a portion of an upper surface of the optical sheets
130.
[0012] Although not shown in detail, the light emitting device 110
includes a light emitting diode chip mounted inside a frame and has
a package structure.
[0013] The light guide plate 150 includes a first area (FA), which
has a gradually decreasing thickness with increasing distance from
an area adjoining the light emitting device 110, and a second area
(SA) having a constant thickness. Here, the general package type
light emitting device 110 has a limit in realizing size reduction
to a certain size or less due to structural features thereof. Thus,
the first area (FA) has a light incident face corresponding to the
size of the light emitting device 110, and has a gradually
decreasing thickness corresponding to the thickness of the second
area (SA).
[0014] The general backlight unit 100 can minimize loss of light
emitted from the light emitting device 110 using the light guide
plate 150 including the first area (FA) having a gradually
decreasing thickness. However, the general backlight unit 100 has a
limit in thickness reduction of the light guide plate 150 due to
the size of the light emitting device 110. Thus, there is a
difficulty following recent trend of decreasing the thickness of
backlight units. Moreover, the first area (FA) has a slope 151 on
an upper portion thereof, thereby causing problems such as light
loss due to light leakage, total reflection, and the like.
SUMMARY
[0015] The present invention is aimed at providing a technology
capable of achieving a slim structure of a backlight unit.
[0016] In addition, the present invention is aimed at providing a
backlight unit having good appearance by minimizing a non-light
emitting area at an edge thereof.
[0017] Further, the present invention is aimed at providing a
backlight unit which realizes a slim structure and has a minimized
non-light emitting area using a light emitting diode chip
exhibiting excellent light efficiency.
[0018] In accordance with one aspect of the present invention, a
backlight unit includes: a light guide plate having an overall flat
structure; a light emitting device disposed on at least one side of
the light guide plate; a first reflector disposed under the light
guide plate and having one side extending to an area in which the
light emitting device is disposed; a second reflector disposed on
the light emitting device; and a housing receiving the light guide
plate, the light emitting device, and the first and second
reflectors, wherein the housing has a side portion on which the
light emitting device is received, the side portion having a
cross-section including a first side defined as a lower surface of
the housing, a second side vertically extending from the first side
in an upper direction of the housing and a third side vertically
extending from the second side in an inner direction of the
housing, and the light emitting device includes a flip-chip type
light emitting diode chip and a wavelength conversion layer
covering an upper surface and both side surfaces of the light
emitting diode chip.
[0019] The backlight unit may further include a circuit board
disposed on the second side within the housing.
[0020] The circuit board may have one surface facing the second
side within the housing and the other surface on which the light
emitting device is mounted.
[0021] The first reflector may have an upper surface facing a lower
surface of the light guide plate and one side surface of the light
emitting device, and a distal end facing a portion of the other
side of the circuit board.
[0022] The second reflector may have a portion extending to a
position between the second side and the circuit board.
[0023] The second reflector may have a portion of an upper surface
contacting a lower surface of the third side, a portion of a lower
surface contacting a portion of the circuit board, and another
portion of the lower surface contacting a portion of an upper
surface of the light guide plate.
[0024] The wavelength conversion layer includes a first layer
covering the upper surface of the light emitting diode chip and a
second layer covering both side surfaces of the light emitting
diode chip, wherein the first layer has a higher thickness than the
second layer.
[0025] The backlight unit further includes: optical sheets disposed
on the light guide plate; and a light shielding tape disposed
parallel to the upper area to cover edges of the optical sheets to
secure the optical sheets while preventing light leakage.
[0026] In accordance with another aspect of the present invention,
a backlight unit includes: a light guide plate having an overall
flat structure; a light emitting device disposed on at least one
side of the light guide plate; and a housing receiving the light
guide plate and the light emitting device, and having a side
portion on which the light emitting device is received, the side
portion including a first side defined as a lower surface of the
housing, a second side vertically extending from the first side in
an upper direction of the housing, and a third side vertically
extending from the second side in an inner direction of the
housing, wherein the light emitting device includes a flip-chip
type light emitting diode chip and a wavelength conversion layer
covering an upper surface and both side surfaces of the light
emitting diode chip, wherein the wavelength conversion layer
includes a first layer covering the upper surface of the light
emitting diode chip and a second layer covering both side surfaces
of light emitting diode chip, and the first layer has a higher
thickness than the second layer.
[0027] The housing has a `` structure divided into an upper area, a
side area and a lower area from top to bottom, and the backlight
unit further includes a circuit board disposed on the side area
within the housing.
[0028] The circuit board may have one surface facing the side area
within the housing, and the other surface on which the light
emitting device is mounted.
[0029] The circuit board may further include a circuit board
disposed on the second side within the housing.
[0030] The first reflector may have an upper surface facing a lower
surface of the light guide plate and one side surface of the light
emitting device, and a distal end facing a portion of the other
surface of the circuit board.
[0031] The second reflector may have a portion extending to a
position between the side area and the circuit board.
[0032] The second reflector may have a portion of an upper surface
contacting a lower surface of the upper area, a portion of a lower
surface contacting a portion of the circuit board, and another
portion of the lower surface contacting a portion of an upper
surface of the light guide plate.
[0033] The light emitting device includes a flip-chip type light
emitting diode chip directly mounted on the circuit board and a
wavelength conversion layer covering an upper surface and both side
surfaces of the light emitting diode chip, wherein the wavelength
conversion layer includes a first layer covering the upper surface
of the light emitting diode chip and a second layer covering both
side surfaces of the light emitting diode chip, and the first layer
has a higher thickness than the second layer.
[0034] The backlight unit may further include optical sheets
disposed on the light guide plate and a light shielding tape
disposed parallel to the upper area to cover edges of the optical
sheets to secure the optical sheets while preventing light
leakage.
[0035] According to the present invention, the backlight unit is
advantageous in realizing a slim structure through an optimized
structure of the light emitting device, the housing and the
reflectors so as to apply the light guide plate having an overall
flat and thin structure, and has an advantage of providing good
appearance by minimizing the non-light emitting area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a schematic sectional view of a backlight unit of
a general small-size liquid crystal display.
[0037] FIG. 2 is a schematic sectional view of a light emitting
device of a backlight unit according to the present invention.
[0038] FIG. 3a is a specific plan view of a light emitting diode
chip of FIG. 2 and FIG. 3b is a sectional view of the light
emitting diode chip taken along line I-I' of FIG. 3a.
[0039] FIG. 4 is an exploded perspective view of a display
including a backlight unit according to one embodiment of the
present invention.
[0040] FIG. 5 is a sectional view of the display taken along line
II-II' of FIG. 4.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0041] Hereinafter, embodiments of the present invention will be
described in detail with reference to the accompanying drawings. It
should be understood that the following embodiments are provided
for complete disclosure and thorough understanding of the invention
by those skilled in the art. Thus, it should be understood that the
present invention is not limited to the following embodiments and
may be embodied in different ways. In addition, in the drawings,
the shapes and the like of components may be exaggerated for
convenience. Like components will be denoted by like reference
numerals throughout the specification. It should be understood by
those skilled in the art that various modifications, changes, and
alterations can be made without departing from the spirit and scope
of the invention. The scope of the invention should be limited only
by the accompanying claims and equivalents thereof.
[0042] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings for easy implementation of the present invention by those
skilled in the art.
[0043] FIG. 2 is a schematic sectional view of a light emitting
device of a backlight unit according to the present invention.
[0044] Referring to FIG. 2, a light emitting device 200 of a
backlight unit according to the present invention includes a light
emitting diode chip 210 and a wavelength conversion layer 240.
[0045] The light emitting diode chip 210 includes a substrate 211
and a semiconductor stack 213, and may further include electrode
pads 215a, 215b.
[0046] The light emitting diode chip 210 is a flip chip and the
electrode pads 215a, 215b are disposed under the light emitting
diode chip.
[0047] The substrate 211 may be a growth substrate for growing
semiconductor layers. For example, the substrate 211 may be a
sapphire substrate or a gallium nitride substrate. In particular,
when the substrate 211 is a sapphire substrate, the semiconductor
stack 213, the sapphire substrate 211 and the wavelength conversion
layer 240 have gradually decreasing indices of refraction in order,
thereby improving light extraction efficiency. In a specific
embodiment, the substrate 211 may be omitted.
[0048] The semiconductor stack 213 may be formed of a gallium
nitride-based compound semiconductor and emit ultraviolet or blue
light.
[0049] The light emitting diode chip 210 is directly mounted on a
circuit board (not shown). The light emitting diode chip 210 is
directly connected to a printed circuit on the circuit is board by
flip-chip bonding without using a bonding wire. According to the
present invention, since the bonding wire is not used to bond the
light emitting diode chip 210 to the circuit board, there is no
need for a molding section for protection of the bonding wire and
for partial removal of the wavelength conversion layer 240 to
expose the bonding pads. Thus, use of the flip chip type light
emitting diode chip enables removal of color deviation and
brightness spots, and simplification of a module preparation
process, as compared with use of a light emitting diode chip using
the bonding wire.
[0050] The wavelength conversion layer 240 covers the light
emitting diode chip 210. As shown, the wavelength conversion layer
240 surrounds an upper surface and both side surfaces of the light
emitting diode chip 210. For example, a phosphor layer may be
formed on the light emitting diode chip 210 and perform wavelength
conversion of light emitted from the light emitting diode chip 210.
The wavelength conversion layer 240 may be coated onto the light
emitting diode chip 210 and may cover the upper surface and the
side surfaces of the light emitting diode chip 210 in a
predetermined thickness.
[0051] The wavelength conversion layer 240 may have a first layer
covering both side surfaces of the light emitting diode chip 210
and a second layer covering the upper surface of the light emitting
diode chip 210, in which the first layer has a thinner thickness
(t1) than a thickness (t2) of the second layer. Here, the light
emitting diode chip 210 is a flip chip type, and has a larger
amount of light emitted toward both side surfaces of the light
emitting diode chip than the amount of light emitted toward the
upper surface thereof. Thus, the light emitting diode chip 210
according to the present invention is designed such that the
thickness (t2) of the second layer receiving relatively large
amounts of light is thicker than the thickness (t1) of the first
layer in order to obtain light in a desired wavelength range.
[0052] With the wavelength conversion layer 240 and light emitted
from the light emitting diode chip 210, the light emitting device
can realize light having various colors, particularly, mixed light
such as white light.
[0053] According to the present invention, the wavelength
conversion layer 240 may be previously formed on the light emitting
diode chip 210 to be mounted on the circuit board together with the
light emitting diode chip 210.
[0054] The structure of the light emitting diode chip 210 will be
described in detail with reference to FIGS. 3a and 3b.
[0055] FIG. 3a is a specific plan view of the light emitting diode
chip of FIG. 2, and FIG. 3b is a sectional view of the light
emitting diode chip taken along line I-I' of FIG. 3a.
[0056] Referring to FIGS. 3a and 3b, the light emitting diode chip
according to the invention includes a first conductive type
semiconductor layer 23 formed on a growth substrate 21, and a
plurality of mesas (M) formed on the first conductive type
semiconductor layer 23 and separated from each other. Each of the
mesas (M) includes an active layer 25 and a second conductive type
semiconductor layer 27. The active layer 25 is disposed between the
first and second conductive type semiconductor layers 23, 27.
Reflective electrodes 30 are disposed on the plurality of mesas
(M), respectively.
[0057] As shown, the plurality of mesas (M) may have an elongated
shape extending in one direction to be parallel to each other. Such
a shape of the mesas can simplify formation of the plurality of
mesas M having the same shape in a plurality of chip areas on the
growth substrate 21.
[0058] The reflective electrodes 30 may be respectively formed on
the mesas M after the plurality of mesas M are formed, but are not
limited thereto. Alternatively, after the second conductive type
semiconductor layer 27 is grown, the reflective electrodes 30 may
be formed on the second conductive type semiconductor layer 27
before the plurality of mesas M are formed. The reflective
electrode 30 covers an overall upper surface of the mesa M and has
substantially the same shape as the shape of the mesa M in top
view.
[0059] The reflective electrodes 30 include a reflective layer 28
and may further include a barrier layer 29. The barrier layer 29
may cover an upper surface and side surfaces of the reflective
layer 28. For example, a pattern of the reflective layer 28 is
formed and the barrier layer 29 is formed thereon, whereby the
barrier layer 29 can be formed to cover the upper and side surfaces
of the reflective layer 28. For example, the reflective layer 28
may be formed through deposition and patterning of Ag, Ag alloy,
Ni/Ag, NiZn/Ag, or TiO/Ag layers. The barrier layer 29 may be
formed of Ni, Cr, Ti, Pt, Rd, Ru, W, Mo, TiW or combinations
thereof, and prevents diffusion or contamination of metallic
materials of the reflective layer.
[0060] After the plurality of mesas M are formed, an edge of the
first conductive type semiconductor layer 23 may also be etched. As
a result, an upper surface of the growth substrate 112 can be
exposed. The first conductive type semiconductor layer 23 may have
a slanted side surface.
[0061] According to the present invention, the light emitting diode
chip further includes a lower insulation layer 31 covering the
plurality of mesas M and the first conductive type semiconductor
layer 23. The lower insulation layer 31 has openings formed at
predetermined locations thereof to allow electrical connection to
the first conductive type semiconductor layer 23 and the second
conductive type semiconductor layer 27 therethrough. For example,
the lower insulation layer 31 may have openings through which the
first conductive type semiconductor layer 23 is exposed, and
openings through which the reflective electrodes 30 are
exposed.
[0062] The openings may be disposed between the mesas M and near
the edge of the substrate 21, and may have an elongated shape
extending along the mesas M. In addition, the openings are disposed
only above the mesas M to be biased towards the same ends of the
mesas.
[0063] The light emitting diode chip according to the present
invention includes a current spreading layer 33 formed on the lower
insulation layer 31. The current spreading layer 33 covers the
plural mesas (M) and the first conductive type semiconductor layer
23. In addition, the current spreading layer 33 is disposed within
an upper area of each of the mesas (M) and has openings for
exposing the reflective electrodes. The current spreading layer 33
may form ohmic contact with the first conductive type semiconductor
layer 23 through the openings of the lower insulation layer 31. The
current spreading layer 33 is insulated from the plurality of mesas
M and the reflective electrodes 30 by the lower insulation layer
31.
[0064] Each of the openings of the current spreading layer 33 has a
larger area than the openings of the lower insulation layer 31 to
prevent the current spreading layer 33 from being connected to the
reflective electrodes 30.
[0065] The current spreading layer 33 is formed over the
substantially entirety of the upper area of the substrate 31
excluding the openings. This structure allows electric current to
easily spread through the current spreading layer 33. The current
spreading layer 33 may include a highly reflective metal layer such
as an Al layer. The highly reflective metal layer may be formed on
a bonding layer such as a Ti, Cr or Ni bonding layer. In addition,
a protective layer having a single layer or multilayer structure of
Ni, Cr, Au, and the like may be formed on the highly reflective
metal layer. The current spreading layer 33 may have, for example,
a multilayer structure of Ti/Al/Ti/Ni/Au.
[0066] According to the present invention, the light emitting diode
chip has an upper insulation layer 35 formed on the current
spreading layer 33. The upper insulation layer 35 has openings
through which the current spreading layer 33 is exposed and
openings through which the reflective electrodes 30 are
exposed.
[0067] The upper insulation layer 35 may be formed of an oxide
insulation layer, a nitride insulation layer, a combination layer
or alternating layers of these insulation layers, or may be formed
using polymers such as polyimides, Teflon, Parylene, and the
like.
[0068] A first pad 37a and a second pad 37b are formed on the upper
insulation layer 35. The first pad 37a is connected to the current
spreading layer 33 through the opening of the upper insulation
layer 35, and the second pad 37b is connected to the reflective
electrodes 30 through the openings of the upper insulation layer
35. The first and second pads 37a, 37b may be used as pads for
connection of bumps or for SMT in order to mount the light emitting
diode on the circuit board.
[0069] The first and second pads 37a, 37b may be formed together by
the same process, for example, by photolithography and etching or
by a lift-off process. The first and second pads 37a, 37b may
include, for example, a bonding layer such as Ti, Cr or Ni, and a
highly conductive metal layer such as Al, Cu, Ag or Au. Each of the
first and second pads 37a, 37b may be formed to have both ends
thereof disposed on the same plane, whereby the light emitting
diode chip may be flip-chip bonded onto a conductive pattern, which
is formed to the same height on the circuit board.
[0070] Then, the growth substrate 21 is divided into individual
light emitting diode chip units, thereby completing fabrication of
light emitting diode chips. The growth substrate 21 may be removed
from the light emitting diode chips before or after being divided
into the individual light emitting diode chip units.
[0071] As described above, the light emitting diode chip according
to the present invention can realize high efficiency and a small
structure, as compared with a general package type light emitting
device.
[0072] FIG. 4 is an exploded perspective view of a display
including a backlight unit according to one embodiment of the
present invention and FIG. 5 is a sectional view of the display
taken along line II-II' of FIG. 4.
[0073] Referring to FIGS. 4 and 5, a small-size display according
to one embodiment of the invention includes a display panel (DP),
and a backlight unit (BLU) disposed at a rear side of the display
panel (DP) and emitting light.
[0074] The display panel (DP) includes a color filter substrate and
a thin film transistor substrate assembled to each other to
maintain a uniform cell gap therebetween while facing each other.
According to the type, the display panel (DP) may further include a
liquid crystal layer between the color filter substrate (FS) and
the thin film transistor substrate (SS).
[0075] Although not shown in detail in the drawings, the thin film
transistor substrate (SS) includes a plurality of gate lines and
data lines crossing each other to define pixels therebetween, and a
thin film transistor disposed in each of crossing areas between the
gate lines and the data lines to be connected to a pixel electrode
disposed in each of the pixels in one-on-one correspondence. The
color filter substrate (FS) includes RGB color filters
corresponding to the respective pixels, a black matrix disposed
along the periphery of the substrate and shielding the gate lines,
data lines and thin film transistors, and a common electrode
covering all of these components.
[0076] The display panel (DP) includes a driver IC (D-IC) mounted
on one edge thereof. The driver IC (D-IC) generates driving signals
driving the display panel in response to external signals.
[0077] The backlight unit (BLU) supplying light to the display
panel (DP) includes a housing 270 partially open at an upper side
thereof, a circuit board 211 disposed on one side within the
housing 270, a plurality of light emitting devices 200 mounted on
the circuit board 211, and a light guide plate 250 disposed
parallel to the light emitting devices 200 to convert point light
into surface light.
[0078] In addition, the backlight unit (BLU) according to the
invention includes optical sheets 230 disposed on the light guide
plate 250 to diffuse and collect light, a first reflector 261
disposed below the light guide plate 250 to reflect light
travelling in a lower direction of the light guide plate 250 toward
the display panel (DP), a second reflector 263 disposed above the
light guide plate 250 to guide light from the light emitting
devices 200 into the light guide plate 250, and a light shielding
tape 290 disposed at an edge of the optical sheets 230 to prevent
light leakage and to secure the optical sheets 230.
[0079] The light shielding tape 290 includes adhesives on both
sides thereof, has a black color, and serves to prevent light
emitted from the backlight unit (BLU) from leaking to the outside
or to an edge of the display panel (DP).
[0080] One side of the housing 270, on which the light emitting
device 200 is disposed, has a cross-section of a `` structure.
[0081] The `` structure may have a first side defined as a lower
surface of the housing 270, a second side vertically extending in
an upper direction from the first side, and a third side vertically
extending in an inner direction of the housing 270 from the second
side.
[0082] Here, the light shielding tape 290 is disposed parallel to
the third side of the `` structure and has no overlapping area
therewith.
[0083] Although the housing 270 is illustrated as having the ``
structure only at one side of the backlight unit (BLU), the present
invention is not limited thereto and may have the `` structure at
both sides, three sides or all four sides of the backlight unit
(BLU) depending upon locations of the light emitting devices
200.
[0084] The circuit board 211 is disposed on an inner side of the ``
structure of the housing 270. That is, the circuit board 211 is
secured at one surface thereof to the second side of the ``
structure. That is, an adhesive material may be formed between the
one surface of the circuit board 211 and the second side. The
circuit board 211 has the other surface facing a lower surface of
the light emitting device 200. Here, a surface having an electrode
of the light emitting device 200 formed thereon is defined as the
lower surface.
[0085] The light emitting device 200 includes a light emitting
diode chip 210 and a wavelength conversion layer 240. The
wavelength conversion layer 240 may have a first layer covering
both side surfaces of the light emitting diode chip 210 and a
second layer covering an upper surface of the light emitting diode
chip 210, in which the first layer has a thinner thickness than the
thickness of the second layer.
[0086] The upper surface of the light emitting device 200 faces a
light incident face of the light guide plate 250. Here, the light
incident face may be defined as one side surface of the light guide
plate 250, through which light emitted from the light emitting
device 200 enters the light guide plate 250.
[0087] In addition, the light emitting device 200 has side surfaces
facing the first and second reflectors 261, 263, respectively.
[0088] The first and second reflectors 261, 263 may be prepared by
coating a reflective material onto a surface of a base layer, or
may be formed of a base layer composed of a reflective material. In
addition, the first and second reflectors 261, 263 may further
include an adhesive material formed on the surface of the base
layer.
[0089] The first and second reflectors 261, 263 enclose the light
emitting device 200, and cover the overall lower surface and the
partial upper surface of the light guide plate 250,
respectively.
[0090] The first reflector 261 may contact the overall lower
surface of the light guide plate 250, and may have one side, which
extends in a direction of the light emitting device 200 to contact
a portion of the other surface of the circuit board 211 while
facing one side surface of the light emitting device 200. That is,
the first reflector 261 may have an upper surface facing the lower
surface of the light guide plate 250 and the one side surface of
the light emitting device 200, and a distal end facing the portion
of the other surface of the circuit board 211. Thus, according to
the present invention, light emitted from the light emitting device
200 can be incident on the light guide plate 250 without loss due
to the first reflector 261 enclosing the portion of the other
surface of the circuit board 211 and the one side surface of the
light emitting device 200.
[0091] The second reflector 263 may contact a portion of the upper
surface of the light guide plate 250, and may be disposed between a
portion of the circuit board 211 and the third side of the housing
270. That is, the second reflector 263 may have a portion of an
upper surface contacting a lower surface of the third side of the
housing 270, a portion of a lower surface contacting the portion of
the circuit board 211, and another portion of the lower surface
contacting the portion of the upper surface of the light guide
plate 250.
[0092] According to the present invention, with the housing 270 of
the `` structure, the high-efficiency flip-chip type light emitting
device 200 received in the housing, and the structure in which the
first and second reflectors 261, 263 enclose the light emitting
device 200, the backlight unit (BLU) can be prepared to a total
thickness (t3), which is 0.2 mm or more thinner than that of a
general backlight unit.
[0093] In addition, the backlight unit (BLU) according to the
present invention can reduce a width (W) of the non-light emitting
area by 0.4 mm or more as compared with the general backlight unit
by minimizing a margin for receiving the light emitting device 200,
with the housing 270 of the `` structure, the high-efficiency
flip-chip type light emitting device 200 received in the housing,
and the structure in which the first and second reflectors 261, 263
enclose the light emitting device 200.
[0094] As described above, the backlight unit (BLU) according to
the embodiment of the present invention is advantageous in
realizing a slim structure through an optimized structure of the
light emitting device 200, the housing 270 and the first and second
reflectors 261, 263 so as to apply the light guide plate 250 having
an overall flat and thin structure, and has an advantage of
providing good appearance by minimizing the non-light emitting
area.
[0095] Although the present invention is illustrated as having the
structure in which the first reflector 261 is separated a
predetermined distance from one side surface of the light emitting
diode chip 210 with reference to FIG. 5, it should be understood
that the present invention is not limited thereto and may also be
embodied by a structure wherein the first reflector 261 contacts
the one side surface of the light emitting diode chip 210.
[0096] Although some embodiments have been described herein, it
should be understood that the present invention is not limited to
certain embodiments. In addition, some features of a certain
embodiment may also be applied to other embodiments in the same or
similar ways without departing from the spirit and scope of the
present invention.
* * * * *