U.S. patent application number 14/588093 was filed with the patent office on 2015-06-25 for light emitting device package, light source module, backlight unit, display apparatus, television set, and illumination apparatus.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Sung A CHOI, Tae Heon HAN, Dae Woon HONG, Man Ki HONG, Young Geun JUN, Jin Mo KIM, Young Taek KIM, Jung Kyu KOOK, Jeong Eun LIM, Jung Kyu PARK, Young Sam PARK, Churl Wung SHIN.
Application Number | 20150176807 14/588093 |
Document ID | / |
Family ID | 44310845 |
Filed Date | 2015-06-25 |
United States Patent
Application |
20150176807 |
Kind Code |
A1 |
PARK; Jung Kyu ; et
al. |
June 25, 2015 |
LIGHT EMITTING DEVICE PACKAGE, LIGHT SOURCE MODULE, BACKLIGHT UNIT,
DISPLAY APPARATUS, TELEVISION SET, AND ILLUMINATION APPARATUS
Abstract
A light source module, a backlight unit, a display apparatus, a
television set, and an illumination apparatus are provided. The
light source module includes: one or more light source units
including a light emitting element emitting light when electricity
is applied thereto; and an optical sheet disposed above the light
source units and exhibiting bidirectional transmittance
distribution function characteristics having first and second peaks
at radiation angles less than 0.degree. and greater than
0.degree..
Inventors: |
PARK; Jung Kyu; (Seoul,
KR) ; PARK; Young Sam; (Seoul, KR) ; CHOI;
Sung A; (Suwon, KR) ; LIM; Jeong Eun;
(Hwaseong, KR) ; KIM; Jin Mo; (Suwon, KR) ;
HONG; Man Ki; (Gwangmyeong, KR) ; HAN; Tae Heon;
(Jeju, KR) ; SHIN; Churl Wung; (Siheung, KR)
; KIM; Young Taek; (Hwaseong, KR) ; HONG; Dae
Woon; (Osan, KR) ; JUN; Young Geun; (Seongnam,
KR) ; KOOK; Jung Kyu; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Gyeonggi-do |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Gyeonggi-do
KR
|
Family ID: |
44310845 |
Appl. No.: |
14/588093 |
Filed: |
December 31, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13098698 |
May 2, 2011 |
8926114 |
|
|
14588093 |
|
|
|
|
Current U.S.
Class: |
362/235 |
Current CPC
Class: |
H01L 2924/181 20130101;
H01L 2224/48257 20130101; H01L 33/58 20130101; H01L 2224/48091
20130101; G02B 19/0071 20130101; H01L 2224/48247 20130101; G02B
19/0014 20130101; F21K 9/60 20160801; H01L 2224/8592 20130101; F21V
11/00 20130101; G02B 19/0061 20130101; G02F 1/133606 20130101; G02F
1/133603 20130101; H01L 2224/48091 20130101; H01L 2924/00012
20130101; H01L 2924/00014 20130101; H01L 2924/181 20130101; F21Y
2115/10 20160801 |
International
Class: |
F21V 11/00 20060101
F21V011/00; F21K 99/00 20060101 F21K099/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2010 |
KR |
10-2010-0040789 |
Dec 24, 2010 |
KR |
10-2010-0134748 |
Feb 24, 2011 |
KR |
10-2011-0016427 |
Claims
1. A light emitting device package comprising: at least one light
emitting element; a lead frame including a rough surface to scatter
at least a part of light emitted from the at least one light
emitting element which is disposed thereon; and a
light-transmissive resin covering at least a portion of the lead
frame and the at least one light emitting element and having a
concave portion
2. The light emitting device package of claim 1, wherein the rough
surface of the lead frame has a GAM index of 0.4 to 1.0.
3. The light emitting device package of claim 1, wherein the rough
surface of the lead frame has a roughness on a micron scale or
less.
4. The light emitting device package of claim 1, wherein the
light-transmissive resin includes a convex portion disposed above
the at least one light emitting element, so that the concave
portion is disposed in the convex portion.
5. The light emitting device package of claim 4, wherein a diameter
of the concave portion is smaller than a maximum diameter of the
convex portion.
6. The light emitting device package of claim 4, wherein center
points of the convex portion and the concave portion are aligned
with each other.
7. The light emitting device package of claim 6, wherein the at
least one light emitting element is disposed on a center line of
the convex portion and the concave portion.
8. The light emitting device package of claim 1, wherein the
light-transmissive resin includes a wavelength conversion
material.
9. The light emitting device package of claim 1, further
comprising: a wavelength conversion layer including at least one of
a phosphor and a quantum dot.
10. The light emitting device package of claim 9, wherein the
wavelength conversion layer is disposed in the light-transmissive
resin separately from the at least one light emitting element.
11. The light emitting device package of claim 10, wherein an
average distance between the wavelength conversion layer and the at
least one light emitting element is more than 500 um.
12. A light emitting device package comprising: at least one light
emitting element; a lead frame including a surface on which the at
least one light emitting element is disposed; and a light
transmissive resin covering at least a portion of the lead frame
and the at least one light emitting element, wherein a luminance of
the light emitting device package has a substantially uniform value
in a range in which a radiation angle is less than 20.degree. and
has a maximum value in a range in which the radiation angle is more
than 50.degree., based on a disposition area of the at least one
light emitting element.
13. The light emitting device package of claim 12, wherein a ratio
between the luminance in the range in which the radiation angle is
less than 20.degree. and the luminance in the range in which the
radiation angle is more than 50.degree. is in a range of 0.29 to
0.34.
14. A backlight unit comprising: a light emitting device package
including at least one light emitting element, a lead frame
including a rough surface to scatter at least a part of light
emitted from the at least one light emitting element which is
disposed thereon, and a light transmissive resin covering at least
a portion of the lead frame and the at least one light emitting
element and having a concave portion; a substrate having a circuit
pattern electrically connected with the light emitting device
package which is mounted thereon; and a diffusion sheet disposed on
the substrate and diffusing a light from the light emitting device
package uniformly.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/098,698, filed on May 2, 2011 in the U.S.
Patent and Trademark Office, which claims priority from Korean
Patent Application No. 10-2010-0040789 filed on Apr. 30, 2010 in
the Korean Intellectual Property Office, Korean Patent Application
No. 10-2010-0134748 filed on Dec. 24, 2010 in the Korean
Intellectual Property Office, and Korean Patent Application No.
10-2011-0016427 filed on Feb. 24, 2011, in the Korean Intellectual
Property Office, the disclosures of which are incorporated herein
by reference in their entirety.
BACKGROUND
[0002] 1. Field
[0003] Apparatuses consistent with exemplary embodiments relate to
a light emitting device package, a light source module, a backlight
unit, a display apparatus, a television set, and an illumination
apparatus.
[0004] 2. Description of the Related Art
[0005] A light emitting diode (LED), a type of semiconductor light
emitting device, is a semiconductor device capable of generating
light of various colors according to a recombination of electrons
and holes at p and n type semiconductor junctions when current is
applied thereto. Compared with a filament-based light emitting
device, a semiconductor light emitting device has various
advantages such as a long lifespan, low power consumption,
excellent initial driving characteristics, high vibration
resistance, and the like, so demand for the semiconductor light
emitting device continues to grow. LEDs using group III-V compound
semiconductors have been recently used. In particular, recently,
group III-nitride semiconductor LEDs capable of emitting light in a
short-wavelength blue light has come to prominence. A group III
nitride compound semiconductor is a direct transition
semiconductor, and may be stably operated at a high temperature, as
compared to other semiconductors, and has therefore been widely
applied to luminous elements, such as LEDs or laser diodes. Such
nitride compound semiconductors are also commonly used as white
light sources in various kinds of devices in various fields such as
keypads, backlights, traffic lights, as well as for airport runway
landing lights and spotlights, and the like.
[0006] This practical use of LEDs in various fields has brought
about the importance of light source units including such LEDs. In
particular, a light source unit for efficiently emitting heat
generated in a light emitting element such as an LED to the outside
is desirable, as a resin part or lens unit encapsulating the light
emitting element may be degraded and this defect may become more
serious with the use of high-power light emitting elements in a
case in which the heat emitted by the light emitting element can
not be efficiently discharged.
[0007] Light source modules used for an LCD backlight, or the like,
conventionally employed cold cathode fluorescent lamps (CCFLs).
However, CCFLs use mercury gas, having disadvantages in that it has
a slow response speed and low color reproducibility (or a color
gamut) and is not suitable for a light, thin, short, and small LCD
panel. In comparison, LED backlights are environmentally-friendly,
have a fast response speed in the range of a few nano-seconds to
fit a high speed response and are thus effective for a video signal
stream, are available for impulsive driving, have a color gamut of
100% or higher, can have a luminance, color temperature, or the
like which are changeable by adjusting the quantity of light
emitted by red, green and blue LEDs, and are suitable for a light,
thin, short, and small LCD panel. As such, LEDs have been actively
employed as light source modules for backlights.
[0008] However, as light emitting diodes are a point light sources,
hot spots may occur from backlight modules employing LEDs, whereby
it may be difficult to provide uniform illumination with respect to
the emitting surface of the backlight module
SUMMARY
[0009] One or more embodiments provide a light source module having
a diffusion sheet, a reduced optical distance and a reduced number
of light sources, a display device having the light source module,
and an illumination apparatus including the light source
module.
[0010] One or more embodiments also provide a backlight unit having
excellent light uniformity while having a smaller thickness.
[0011] One or more embodiments also provide a backlight unit which
is thin and has excellent light uniformity by including the
foregoing light source module.
[0012] According to an aspect of an exemplary embodiment, there is
provided a light source module including: one or more light source
units including a light emitting element emitting light when
electricity is applied thereto; and an optical sheet disposed above
the light source units and exhibiting bidirectional transmittance
distribution function characteristics having first and second peaks
at radiation angles less than 0.degree. and greater than
0.degree..
[0013] The light source units may exhibit light distribution
patterns having first and second peaks at the radiation angles less
than 0.degree. and greater than 0.degree..
[0014] The illumination angle (or orientation angle) of the light
source units may be 120.degree. or greater.
[0015] The difference between the radiation angle smaller than
0.degree. and that greater than 0.degree. may be 20.degree. to
50.degree..
[0016] The light source units may exhibit light distribution
patterns having a peak at a radiation angle of 0.degree..
[0017] Each of the light source units may include a lens unit
disposed in a path of light emitted from the light emitting
element.
[0018] The light source units may be provided in the form of a
light emitting element package. The light source module may further
include a circuit board on which the light emitting element is
mounted, and the lens unit may be disposed to be in contact with
the circuit board.
[0019] The lens unit may have such a shape that an area thereof
corresponding to an upright portion of the light emitting element
is relatively recessed toward the light emitting element compared
with other areas of the lens unit.
[0020] The optical sheet may have a depression and protrusion
structure formed on one surface thereof.
[0021] The depression and protrusion structure may be formed on the
side of the optical sheet where light made incident from the light
source unit is transmitted through the optical sheet.
[0022] The depression and protrusion structure may have a plurality
of structures having a pyramid shape, at least some of the
plurality of pyramid-shaped structures may have a plurality of
sloped faces disposed to be sloped to a horizontal plane, and the
plurality of sloped faces may have different tilt angles. In
alternative embodiments, a polygonal cone shape may be used instead
of the pyramid shape.
[0023] The sloped faces of mutually adjacent pyramid-shaped
structures among the plurality of pyramid-shaped structures may
have different tilt angles.
[0024] The plurality of pyramid-shaped structures may have
different sizes, and based on one pyramid-shaped structure, other
pyramid-shaped structures are aperiodically disposed in the
vicinity of the one pyramid-shaped structure, and the aperiodical
disposition structure may be periodically repeated to form the
depression and protrusion structure.
[0025] At least some of the plurality of pyramid-shaped structures
may have different heights.
[0026] At least some of the plurality of pyramid-shaped structures
may overlap with different adjacent structures.
[0027] The depression and protrusion structure may have a plurality
of conic structures.
[0028] The plurality of conic structures may be arranged in rows
and columns.
[0029] The optical sheet may have a depression and protrusion
structure, individual depressions and protrusions having a conical
shape and both planar lateral faces and a curved lateral face.
[0030] The optical sheet may not include light diffusion particles
therein.
[0031] The light source module may further include a diffusion
sheet disposed in a path of light transmitted through the optical
sheet after being emitted from the light source unit, and having
diffusion particles dispersed in the interior of a
light-transmissive base. In this case, the optical sheet may have a
depression and protrusion structure formed on one surface thereof,
and the depression and protrusion structure may be formed on the
side of the optical sheet where light made incident from the light
source unit is transmitted through the optical sheet.
[0032] The optical sheet and the diffusion sheet may be disposed to
be spaced apart, or the diffusion sheet may be disposed to be
stacked on the optical sheet.
[0033] A plurality of light source units may be arranged on the
circuit board, and the distance between the circuit board and the
diffusion speed may be smaller than or equal to a half of the pitch
between the plurality of light source units.
[0034] According to an aspect of another exemplary embodiment,
there is provided a backlight unit including: one or more light
source units including a light emitting element emitting light when
electricity is applied thereto; an optical sheet disposed above the
light source units and exhibiting bidirectional transmittance
distribution function characteristics having first and second peaks
at radiation angles less than 0.degree. and greater than 0.degree.;
and a diffusion sheet disposed in the path of light transmitted
through the optical sheet after having been emitted from the light
source units, and having diffusion particles dispersed in a
light-transmissive base.
[0035] The backlight unit may further include: a luminance
enhancement sheet disposed in the path of light transmitted through
the diffusion sheet.
[0036] According to an aspect of another exemplary embodiment,
there is provided a display apparatus including: one or more light
source units including a light emitting element emitting light when
electricity is applied thereto; an optical sheet disposed above the
light source units and exhibiting bidirectional transmittance
distribution function characteristics having first and second peaks
at radiation angles less than 0.degree. and greater than 0.degree.;
a diffusion sheet disposed in the path of light transmitted through
the optical sheet after having been emitted from the light source
units, and having diffusion particles dispersed in a
light-transmissive base; and a display panel disposed at an upper
portion of the diffusion sheet.
[0037] According to n aspect of another exemplary embodiment, there
is provided a television set including the foregoing display
apparatus.
[0038] According to an aspect of another exemplary embodiment,
there is provided an illumination apparatus including: one or more
light source units including a light emitting element emitting
light when electricity is applied thereto; an optical sheet
disposed above the light source units and exhibiting bidirectional
transmittance distribution function characteristics having first
and second peaks at radiation angles less than 0.degree. and
greater than 0.degree.; a housing disposed to surround the light
source units and the optical sheet; and a socket structure
electrically connected to the light source units.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The above and/or other aspects, features and advantages will
be more clearly understood from the following detailed description
taken in conjunction with the accompanying drawings, in which:
[0040] FIG. 1 is a cross-sectional view schematically showing a
light source module according to an exemplary embodiment;
[0041] FIG. 2 is a cross-sectional view of an exemplary light
source unit of FIG. 1;
[0042] FIG. 3(a) is a cross-sectional view of another exemplary
light source unit;
[0043] FIG. 3(b) is a top plan view of the light source unit of
FIG. 3(a);
[0044] FIGS. 4(a) and 4(b) are graphs showing examples of light
distribution pattern of the light source unit of FIG. 1, in which a
horizontal axis is a radiation angle and the light intensity of a
vertical axis indicates relative values;
[0045] FIG. 5 is a cross-sectional view of another exemplary light
source unit;
[0046] FIG. 6 is a cross-sectional view showing another example of
the light source unit of FIG. 1;
[0047] FIG. 7 is a graph showing another example of a light
distribution pattern of the light source unit of FIG. 1;
[0048] FIG. 8 is a cross-sectional view schematically showing an
example of an optical sheet which may be employed in the light
source module of FIG. 1;
[0049] FIG. 9 is a photographic image obtained by capturing a
surface of an exemplary optical sheet;
[0050] FIG. 10 is a cross-sectional view of another exemplary light
source unit;
[0051] FIG. 11 is a graph showing an example of a bidirectional
transmittance distribution function (BTDF) of an optical sheet;
[0052] FIGS. 12 and 13 show light emission distributions which can
be obtained from optical sheets according to comparative
examples;
[0053] FIG. 14 shows a light emission distribution obtained from an
optical sheet having the BTDF of FIG. 11;
[0054] FIGS. 15 and 16 show light emission distributions according
to a comparative example and an exemplary embodiment;
[0055] FIG. 17 is a perspective view schematically showing another
example of an optical sheet;
[0056] FIG. 18 is a cross-sectional view showing an example of a
diffusion sheet which may be employed in the light source module of
FIG. 1;
[0057] FIG. 19 is a cross-sectional view schematically showing a
configuration of a light source module according to an exemplary
embodiment and according to a comparative example;
[0058] FIG. 20 is a view showing a light emission distribution at
an upper portion of the light source module of FIG. 19;
[0059] FIGS. 21, 22, and 23 are cross-sectional views schematically
showing light source modules according to exemplary
embodiments;
[0060] FIG. 24 is a schematic perspective view of another exemplary
light source unit;
[0061] FIG. 25 is a cross-sectional view of the light source unit
of FIG. 19, taken along line A-A';
[0062] FIGS. 26(a) and 26(b) are diagrams, each schematically
illustrating a luminance distribution at an upper surface of a lens
unit including a convex portion and a concave portion formed within
the convex portion;
[0063] FIGS. 27(a) and 27(b), FIGS. 28(a) and 28(b) and FIGS. 29(a)
and 29(b), respectively show a diagram and a photograph explaining
a light distribution according to a surface roughness of a lead
frame;
[0064] FIGS. 30(a) and 30(b) show a radiation pattern and a
luminance distribution according to a GAM index of a lead frame in
a light emitting device package according to an exemplary
embodiment;
[0065] FIG. 31 is a diagram illustrating a light source unit
according to an exemplary embodiment, when viewed from the
side;
[0066] FIG. 32 is a diagram illustrating a backlight unit according
to an exemplary embodiment, when viewed from the side;
[0067] FIG. 33 shows a radiation pattern of a light emitting device
package according to a thickness of a wavelength conversion layer
thereof;
[0068] FIG. 34 is a diagram schematically illustrating a luminance
distribution of the light emitting device package of FIG. 33;
[0069] FIG. 35 is a cross-sectional view of a light emitting
element package according to an exemplary embodiment;
[0070] FIG. 36 is a plan view of the light emitting element package
of FIG. 30 when viewed from above;
[0071] FIG. 37 is an enlarged view of a peripheral region of a
wavelength conversion unit and a conductive wire in the light
emitting element package shown in FIG. 30;
[0072] FIGS. 38, 39, and 40 are cross-sectional views of light
emitting element packages according to exemplary embodiments;
[0073] FIG. 41 is a plan view of a light emitting element package
according to another exemplary embodiment;
[0074] FIG. 42 is a plan view of a light emitting element package
according to another exemplary embodiment;
[0075] FIG. 43 is a schematic perspective view of first and second
lead frames of the light emitting element package shown in FIG.
42;
[0076] FIG. 44 is a plan view of a light emitting element package
according to another exemplary embodiment; and
[0077] FIG. 45 is a cross-sectional view of the light emitting
element package of FIG. 44.
DETAILED DESCRIPTION
[0078] Exemplary embodiments will now be described in detail with
reference to the accompanying drawings. The invention may, however,
be embodied in many different forms and should not be construed as
limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey the scope of the invention to
those skilled in the art. In the drawings, the shapes and
dimensions may be exaggerated for clarity, and the same reference
numerals will be used throughout to designate the same or like
components.
[0079] With reference to FIG. 1, a light source module 100 includes
a light source unit 101 and an optical sheet 103, and further
includes a circuit board 102 on which the light source unit 101 is
mounted, and a diffusion sheet 104 and a luminance enhancement
sheet 105 disposed at an upper side of the optical sheet 103.
[0080] As shown in FIG. 2, the light source unit 101 may include a
light emitting element 111 which emits light when an electrical
signal is applied thereto, and the light source module 100 may
include one or more light source units 101 (a plurality of light
source units in the present exemplary embodiment). In this case, a
lens unit 113 may be disposed on a path of light emitted from the
light emitting element 111. In addition, the light source unit 101
may include a package substrate 112 electrically connected to the
light emitting element 111. The package substrate 112 may be, for
example, a printed circuit board (PCB), a metal core PCB (MCPCB),
an a metal PCB (MPCB), a flexible PCB (FPCB), or the like, or a
lead frame. The light emitting element 111 may be any element so
long as it emits light when an electrical signal is applied
thereto. An LED may be used as the light emitting element 111. An
LED in which a semiconductor layer is epitaxially grown on a growth
substrate may be used. The growth substrate may be made of
sapphire; however, it is not limited thereto. The growth substrate
may be made of a substrate material such as spinel, silicon carbide
(SiC), gallium nitride (GaN), gallium arsenide (GaAs) or the like,
as would be understood by one of skill in the art. In particular,
the LED may be made of BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN,
BAlGaN, BInAlGaN or the like, and may be doped with Si, Zn or the
like. In addition, a light emitting layer of the LED may be made of
a nitride semiconductor formed of
InxAlyGa1-x-y(0.ltoreq.X.ltoreq.1, 0.ltoreq.Y.ltoreq.1,
X+Y.ltoreq.1), and may have a single or multiple quantum well
structure, whereby the output thereof may be improved.
[0081] The example illustrated in FIG. 2 has a structure in which
the light source unit 101 includes one light emitting element 111,
but the light source unit 101 may include a plurality of light
emitting elements. For example, one light source unit 101 may
include light emitting elements respectively emitting red (R),
green (G), and blue (B) light. Accordingly, white light having
excellent mixture characteristics of three-color light can be
obtained by using a light source unit 101 including R, G, and B
light emitting elements and an optical sheet 103 described herein.
Of course, light emitted from the plurality of light source units
101 provided in the light source module may also have different
respective colors.
[0082] The lens unit 113 may have a wavelength conversion material
(e.g., a phosphor, quantum dots, or the like) dispersed therein in
order to convert light emitted from the light emitting element 111
into a different color. For example, the light emitting element 111
may emit blue light and the wavelength conversion material may
include at least one of green, yellow, and red phosphors.
Alternately, the wavelength conversion material may be applied to a
different position, rather than to the lens unit 113. For example,
the wavelength conversion material may be coated on the surface of
the light emitting element 111 or may be disposed at a position
spaced apart from the light emitting element 111 at a package
level. In addition, the wavelength conversion material may be
applied to the surface or the interior of the optical sheet 103 (to
be described).
[0083] As shown in FIG. 2 the light source units 101 may be
disposed on the flat package substrate 112. Alternately, the light
emitting element 111 may be disposed in a package main body having
a reflective cup-like shape. The light emitting element 111 may be
modified to have various other structures so long as it has a light
distribution pattern intended in the present exemplary embodiment.
For example, in a light source unit 101', as illustrated in FIG.
3(a), the light emitting element 111 may be disposed on at least
one of first and second lead frames 112a and 112b and electrically
connected by wires W to the first and second lead frames 112a and
112b. One conductive wire W may be used, or another means for
electrically connecting the light emitting element to the first and
second lead frames may be used, according to the configuration of
the light emitting element 111. For example, when electrodes of the
light emitting element 111 are formed on upper and lower surfaces
of a light emission structure interposed therebetween, only one
conductive wire W may be used, and when the light emitting element
111 is disposed in the form of a flip chip on two lead frames 112a
and 112b, the conductive wire W may not be used.
[0084] As shown in FIGS. 3(a) and 3(b), lower surfaces of the first
and second lead frames 112a and 112b may be exposed to be provided
as an electricity connection part, and with this structure, a heat
releasing effect can be provided. In this case, as shown in the top
plan view of FIG. 3(b), the first lead frame 112a may have a
portion thereof which protrudes toward the second lead frame 112b
and the second lead frame 112b may have a corresponding recessed
portion to receive the protruding portion of the first lead frame
112a. This structure may provide an improved coupling force between
the lead frames and the lens unit 113. The lens unit 113 may be
made of a light-transmissive resin and may be combined with the
first and second lead frames 112a and 112b to support the first and
second lead frames 112a and 112b. Although not shown, the first and
second lead frames 112a and 112b may include one or more holes or
step structures, or a combination thereof in order to increase a
contact area with the lens unit 113. Examples of holes and step
structures are described below with respect to FIGS. 41-45.
[0085] Additional exemplary package structures which may be used
for a light source unit are described below with respect to FIGS.
24-45. However, the light source unit 101 may be provided in a
different form, rather than a package form. Namely, the light
source unit 101 may have a chip-on-board (COB) structure as shown
in FIG. 5 in which the light emitting element 111 is directly
mounted on the circuit board 102 and the lens unit 114 may be
disposed on the circuit board 102 so as to be in contact with the
circuit board. Meanwhile, the circuit board 102 illustrated in FIG.
1 provides a mounting area for the light source unit 101. For
example, a PCB, an MCPCB, an MPCB, an FPCB, or the like, used in
the art may be employed as the circuit board 102. In this case, the
circuit board 102 may have a wiring pattern (not shown) disposed on
a surface or in the interior thereof, and the wiring pattern may be
electrically connected to the light source unit 101.
[0086] In the present exemplary embodiment, the light source unit
101 has a light distribution pattern as shown in FIG. 4. In detail,
the light source unit 101 may have a light distribution pattern
having first and second peaks at radiation angles less than
0.degree. and greater than 0.degree., rather than at an upright
portion, i.e., at the angle of 0.degree.. For example, as shown in
FIGS. 4(a) and 4(b), the light distribution pattern of the light
source unit 101 may have a total of two peaks, namely, one peak at
a radiation angle smaller than 0.degree. and one peak at a
radiation angle greater than 0.degree.. In FIG. 4, a pattern
without a peak at a radiation angle of 0.degree. is illustrated,
but according to the structure of the light source unit 101, a
local peak may also be generated at the radiation angle of
0.degree., and in this case, the peak at the radiation angle of
0.degree. may have a size smaller than that of the first and second
peaks. The light source unit 101 having such a light distribution
pattern has a light intensity (or illumination) greater at the
peripheral (or marginal) portions than at the upright portion
(i.e., at the radiation angle of 0.degree.), and may have a
relatively large orientation angle value (120.degree. or greater).
These optical characteristics of the light source unit 101, namely,
that light spreads to the marginal portions of the upright portion,
rather than being concentrated in the upright portion of the light
source unit 101, are advantageous for a light mixture with a
different light source unit 101 in the upper area of the light
source unit 101, and in particular, the light mixture effect can be
further improved when the light source unit 101 is combined with
the optical sheet 103 having the optical characteristics proposed
in the present exemplary embodiment (to be described).
[0087] In order to allow the light source unit 101 to have the
light distribution pattern illustrated in FIGS. 4(a) and 4(b), as
shown in FIGS. 2, 3, 5, 24, and 25, the lens units 113 may have a
shape in which an area corresponding to the area directly above the
light emitting element 111 is recessed toward the light emitting
element 111, as compared with other areas, thereby inducing light
to be irradiated to the peripheral areas, rather than the area
directly above the light emitting element, thus providing a greater
orientation angle. The shape of the lens units illustrated in FIGS.
2, 3, 5, 24, and 25 are merely illustrative, and the shapes of a
light source unit and a lens unit having the light distribution
pattern similar to that of FIGS. 4(a) and 4(b) may be variably
modified. For example, the lens unit may have a hemispherical
shape, and diffusion particles or a reflective part having an
appropriate shape may be applied to a surface or the interior of
the lens unit to obtain similar optical characteristics.
[0088] In the case of the light source unit, as an alternative to
the described structure having the radiation angles less than
0.degree. and greater than 0.degree., a structure having a peak at
the radiation angle of 0.degree. at which light intensity is the
strongest (a so called Gaussian pattern), as shown in FIG. 7, may
be also used. A light source unit 101'' in FIG. 6 is an example of
a structure with such a light distribution pattern, which includes
a hemispherical lens unit 113' covering the light emitting element
111. The shapes of the lens units of the light source unit of FIGS.
3 and 5 may also be changed to be similar to that of the lens unit
13' of FIG. 6. When the light source unit has the light
distribution pattern as shown in FIG. 7, namely, when light
intensity is strongest at the upright portion of the light source
unit 101'', the optical sheet 103 having a function of inducing
light, which has been made incident in a vertical direction, to a
lateral direction may be disposed above the light source unit 101''
to obtain a high level of light mixture effect.
[0089] The optical sheet 103 disposed on the path of light emitted
from the light source unit 101 (in this embodiment, the optical
sheet 103 is disposed above the light source unit) has similar
light distribution characteristics to those of the light source
unit 101 illustrated in FIG. 4. This will now be described with
reference to FIGS. 8 to 16. FIG. 8 is a cross-sectional view
schematically showing an example of an optical sheet which may be
employed in the light source module of FIG. 1. FIG. 9 is an image
of a photograph obtained by capturing a surface of the optical
sheet of FIG. 8. FIG. 11 is a graph showing an example of a
bidirectional transmittance distribution function (BTDF) of the
optical sheet. In this case, the BTDF of the optical sheet can be
obtained by measuring radiation patterns made by a laser beam made
incident in a direction perpendicular to the optical sheet,
according to radiation angles.
[0090] With reference to FIG. 11, the BTDF characteristics of the
optical sheet 103 have first and second peaks at radiation angles
less than 0.degree. and greater than 0.degree.. In detail, the BTDF
characteristics have one peak at a radiation angle smaller than 0
and one peak at a radiation angle greater than 0.degree.. In this
case, the difference .theta. between the radiation angle smaller
than 0.degree. and the radiation angle greater than 0.degree. may
range from 20.degree. to 50.degree.. When the optical sheet 103
having such light-transmissive characteristics is combined with the
light source units 101, 101' and 101'' having the foregoing light
distribution patterns, light uniformity at the upper portion of the
optical sheet 103 can be further improved (to be described later).
Also, although not shown, a wavelength conversion material (e.g.,
at least one of yellow, green, and red wavelength conversion
materials) such as a phosphor or a quantum dot may be applied to
the surface or the interior of the optical sheet 103 to convert
light (e.g., blue light) emitted from the light source unit 101,
and accordingly, the light source module 100 can obtain light of an
intended color, e.g., white light having high color rendering
properties.
[0091] The optical sheet 103 may be employed to have various
structures exhibiting the foregoing light-transmissive
characteristics. For example, as shown in FIG. 8, the optical sheet
103 may have a depression and protrusion structure 122 formed on
one surface thereof. In detail, the optical sheet 103 includes a
light-transmissive base 121 and the depression and protrusion
structure 122 extending from the light-transmissive base 121. In
this case, the depression and protrusion structure 122 is formed at
the side where light made incident from the light source unit 101
is emitted from the optical sheet 103. Namely, the light source
unit 101 may be disposed at a lower side of the light-transmissive
base 121 as shown in FIG. 8. The light-transmissive base 121 may
have a thickness ranging from about 0.5 mm to about 1.5 mm and may
be made of a material commonly used to fabricate an optical element
in the art, such as poly methyl methacrylate (PMMA), or the like.
The depression and protrusion structure 122 may have a thickness of
tens of micrometers (.mu.m) and may be made of the same material as
that of the light-transmissive base 121. The depression and
protrusion structure 122 may also be formed by applying a
UV-setting or thermosetting material to the light-transmissive base
121, transferring depressions and protrusions thereto, and
performing a curing process thereon. In this case, the optical
sheet 103 may not necessarily have the depression and protrusion
structure 122 but may have any optical structures (e.g., a
diffusion structure, a reflective structure, or the like) other
than the depression and protrusion structure 122, so long as it can
exhibit the BTDF characteristics of FIG. 10. Also, as shown in FIG.
10, a depression and protrusion structure having a shape, which is
the same as or similar to the depression and protrusion structure
122 of FIG. 8, may be applied to the surface of the lens 113'', and
in this case, the light source module may not include the optical
sheet 103.
[0092] The shape of the depression and protrusion structure 122 may
be appropriately adjusted to allow the BTDF of the optical sheet
103 to exhibit the characteristics as shown in FIG. 11, and the
depression and protrusion structure 122 may have a conical shape so
as to appropriately spread light, which has been made incident in a
vertical direction, to all vicinities thereof. In this case, the
depression and protrusion structure is not necessarily limited to
the conical shape and a depression and protrusion structure having
any other shape can be employed so long as it can exhibit desired
BTDF characteristics, such as those illustrated in FIG. 11. When
the depression and protrusion structure has a conical shape, the
path of light, which has been made incident in a vertical
direction, may be changed by the sloped lateral side of the conic
structure so as to spread in a lateral direction. The depression
and protrusion structure may have pyramid-shaped structures. The
pyramid-shaped structures may have bases which are triangles,
quadrilaterals, or other polygons. Here, besides a pyramid or a
circular cone, the structures may include complex forms thereof;
namely, the conic or pyramid structure may include both a planar
lateral face and a curved lateral face. For example, as shown in
FIGS. 8 and 9, the depression and protrusion structure 122 may have
a plurality of structures having a pyramid shape, and at least some
of the plurality of pyramid structures have a plurality of sloped
faces disposed to be sloped to an upper or lower surface of the
light-transmissive base 121. In detail, as shown in FIGS. 8 and 9,
two or more sloped faces of the at least some of the plurality of
pyramid-shaped structures may have different tilt angles, and in
addition, sloped faces of mutually adjacent pyramid-shaped
structures may also have different tilt angles. Also, as shown in
FIG. 9, at least some of the plurality of pyramid-shaped structures
may have different sizes and heights. Based on one pyramid-shaped
structure, the other pyramid-shaped structures may be aperiodically
disposed in the vicinity of the one prism structure. In this case,
in an example of a method for completing the optical sheet 103,
such an aperiodical disposition structure may be periodically
repeated. Also, as shown in FIG. 9, at least some of the plurality
of pyramid-shaped structures may overlap with other adjacent
structures.
[0093] As shown in the optical sheet 103' according to a
modification of an exemplary embodiment as illustrated in FIG. 17,
the optical sheet 103' may have other structures, e.g., conic
structures, in order to provide the foregoing optical
characteristics, to change the path of light, which has been made
incident in a vertical direction, and to induce the light to move
in a lateral direction. In this case, a plurality of circular
conical structures may be provided and arranged in rows and
columns.
[0094] In order for light to appropriately spread in the lateral
direction by virtue of the conical structures, the optical sheet
103 may have a high level of transparency. Therefore, the optical
sheet 103 may not include light diffusion particles. When the
optical sheet 103 does not include light diffusion particles, a
loss of light which would be caused by the light diffusion
particles can be minimized to improve the luminous efficiency of
the light source module 100 using the optical sheet 103. However,
this does not mean that the optical sheet 103 must not include any
light diffusion particles therein, but light diffusion particles
may be unavoidably present due to the process of fabricating the
optical sheet 103 or a very small amount of light diffusion
particles may be purposefully dispersed in the interior of the
optical sheet 103.
[0095] As described above, in having the structure in which the
polygonal cone-shaped structures are aperiodically disposed, the
optical sheet 103 can exhibit the foregoing BTDF characteristics of
FIG. 11, and these will now be described with reference to FIGS.
12, 13 and 14.
[0096] FIGS. 12 and 13 show light emission distributions which can
be obtained from optical sheets according to comparative examples.
Specifically, the light emission distributions are obtained by
measuring light intensity (or illumination) after irradiating light
to a lower side of the light source unit having the light
distribution pattern of FIG. 4. FIG. 14 shows a light emission
distribution which can be obtained from an optical sheet having the
BTDF of FIG. 11. Similarly, the light emission distribution is
obtained by irradiating light to a lower side of the light source
unit.
[0097] The optical sheet of FIG. 12 has a pattern S1 in which
trigonal prisms having a stripe shape are arranged in one
direction, exhibiting a light emission distribution in which light
is spread only left and right (as shown in FIG. 12) by two sloped
faces of the trigonal prisms. The optical sheet of FIG. 13 has a
pattern S2 in which quadrangular pyramids are regularly arranged in
rows and columns, exhibiting a light emission distribution in which
light is spread only up, down, left, and right (as shown in FIG.
13) by the four sloped faces of the quadrangular pyramids. In this
manner, when the optical sheets of FIGS. 12 and 13 are used, the
light emission distributions have particular directionalities,
rather than having the BTDF characteristics as described above with
reference to FIG. 11. In comparison, as shown in a light emission
distribution of FIG. 14, when an optical sheet according to
exemplary embodiments described herein is used, the light emission
distribution does not have directionality but the same light
emission characteristics are obtained substantially in every
direction.
[0098] The results obtained by comparing the effects of an optical
sheet as proposed herein in a different aspect will now be
described with reference to FIGS. 15 and 16. FIGS. 15 and 16 show
light emission distributions according to a comparative example and
according to an exemplary embodiment. First, in case of FIG. 15,
light emission distributions were measured by disposing the
diffusion sheet 104 at an upper side of different light source
units 101 and 101' having different light distribution patterns,
and in this case, the diffusion sheet 104 has a structure in which
diffusion particles are dispersed in a light-transmissive base (to
be described). In this case, the light source units 101 and 101'
have the structure as described above with reference to FIGS. 2 and
6. In case of FIG. 16, light emission distributions were measured
by replacing the diffusion sheet 104 of the comparative example of
FIG. 15 with an optical sheet 103.
[0099] First, with reference to FIG. 15, in case of the comparative
example, it is noted that light intensity is relatively great in
the regions where the light source units 101 and 101' are located,
which means that the effect that light, which has been made
incident in a direction perpendicular to the diffusion sheet 104,
spreads in the lateral direction is not great. In comparison, as
noted in the light emission distribution of FIG. 16, when the
optical sheet 103 proposed in an exemplary embodiment is disposed
above the light source units 101 and 101', the area of light
emission is reduced but the light intensity is more uniform
overall, which means that light has been spread sufficiently in the
lateral direction by the optical sheet 103 having the conic
structures. In particular, with reference to FIG. 16, it can be
noted that such an effect can be obtained with respect to both the
light source unit 101 having first and second peaks at the
radiation angles less than 0.degree. and greater than 0.degree. and
the light source unit 101 having the peak at the radiation angle of
0.degree.. Meanwhile, as described above, when the optical sheet
103 is in use, the overall light emission area may be small;
however, the light emission area can be increased by adjusting the
distance between the optical sheet 103 and the light source units
101 and 101', or by disposing the diffusion sheet 104 at an upper
side of the optical sheet 103 as shown in the structure illustrated
in FIG. 1.
[0100] The diffusion sheet 104, disposed on a light emission side
of the optical sheet 103 (the diffusion sheet 104 may be disposed
at an upper side of the optical sheet 103), is similar to the
optical sheet 103 in a functional aspect, in that it changes the
paths of light made incident from a plurality of paths and mixes
them, but an internal structure of the diffusion sheet 104 is
different from that of the optical sheet 103. Namely, as shown in
FIG. 18, the diffusion sheet 104 may include a light-transmissive
base 131 and diffusion particles 132 dispersed in the
light-transmissive base 131. The diffusion particles 132 may be
made of a material such as TiO.sub.2, SiO.sub.2, or the like. The
term `diffusion sheet` is used, but this generally refers to an
optical structure which performs a diffusion function and has a
planar shape, and an optical element such as a `diffusion plate`
whose shape is not deformed although there is no other structure
supporting the diffusion plate may be included. A luminance
enhancement sheet 105 disposed on a light emission side of the
diffusion sheet 104 (the luminance enhancement sheet 105 may be
disposed on an upper side of the diffusion sheet 104) serves to
direct light in an upward direction in order to provide light to a
liquid crystal panel, or the like. For example, the luminance
enhancement sheet 105 may have a plurality of pyramid-shaped
structures formed thereon. In this case, for example, a dual
brightness enhancement film (DBEF), a brightness enhancement film
(BEF), or the like, may be used as the luminance enhancement sheet
105.
[0101] A light mixture effect according to the configuration of the
light source module 100, namely, the structure using both the
optical sheet 103 and the diffusion sheet 104, proposed in the
present exemplary embodiment as described above will now be
described. FIG. 19 is a cross-sectional view schematically showing
the configuration of a light source module according to an
exemplary embodiment and that of comparative example. In FIG. 19,
based on the dotted line, the left side corresponds to the light
source module of FIG. 1 and the right side corresponds to the
structure in which a diffusion sheet 104' is employed, instead of
the optical sheet 103 in the light source module of FIG. 1. In this
case, the light source unit 101 has the light distribution pattern
illustrated in FIG. 4, and the diffusion sheet 104' has a structure
in which diffusion particles are dispersed in a light-transmissive
base, similar to the structure illustrated in FIG. 18.
[0102] FIG. 20 is a view showing a light emission distribution at
an upper portion of the light source module of FIG. 19. In FIG. 20,
the area indicated by the dotted line corresponds to the left
structure, namely, the structure using the optical sheet 103 and
the diffusion sheet 104 in FIG. 19. As shown in FIG. 20, relatively
excellent light mixture characteristics can be obtained with the
structure in which the optical sheet 103 and the diffusion sheet
104 are combined. Namely, the light mixture characteristics are
superior when the optical sheet 103 and the diffusion sheet 104 are
combined, compared with the case in which two diffusion sheets 104
and 104' are employed, due to the fact that at least a portion of
light made incident in the vertical direction is appropriately
blocked by the optical sheet 103. Also, such a light mixture
characteristics enhancement effect can be more remarkable when the
light source unit 101 having the light distribution pattern of FIG.
4, rather than the Gaussian light distribution pattern, is used.
When the light mixture effect is improved, the optical distance L
(in FIG. 1) corresponding to the position at which the diffusion
sheet is disposed can be reduced and the pitch P between the light
source units 101 can be increased simultaneously or independently,
and thus, the number of the light source units 101 can be
reduced.
[0103] In detail, with reference to FIG. 1, the distance L between
the circuit board 102 and the diffusion sheet 104 may be smaller
than or equal to a half of the pitch P between the light source
units 101, which is very effective level as compared with the case
in which L/P is approximately 1 when the light source unit having
the Gaussian light distribution pattern is used. Thus, although the
optical distance or the number of the light source units is
reduced, excellent light uniformity can be obtained. Thus, when the
light source module is used as a backlight unit, display apparatus
images, such as those of an LCD, or the like, can become sharper
and clearer, and in addition, the thickness of a television set,
the number of light sources, power consumption, and the like,
having such a display apparatus can be reduced. In addition, the
light source module can be also used for an illumination device, as
well as for a backlight unit, a display apparatus, a television
set, and also in this case, the thickness and number of the light
sources can be reduced. Namely, a housing, a socket structure, or
the like, may be coupled to the periphery of the light source
module having the foregoing structure and a lens having a
hemispherical shape may be disposed on a light emission path of the
light source module so as to be used as an illumination
apparatus.
[0104] Meanwhile, the light source module having the foregoing
structure can be variably modified so long as the optical
characteristics of the light source unit 101 and the optical sheet
103 are maintained, examples of which will now be described with
reference to FIGS. 21, 22 and 23. In case of a light source module
as shown in FIG. 21, its structure is similar to that of the light
source module of FIG. 1, except that the diffusion sheet 104 is
attached to the optical sheet 103, namely, the diffusion sheet 104
is stacked on the optical sheet 103, unlike a light source module
in which the diffusion sheet 104 and the optical sheet 103 are
separated. With this structure, the optical distance can be
reduced, so the light source module can have a compact
structure.
[0105] A light source module of FIG. 22 is different from the light
source module of FIG. 1 in that the circuit board 102 is divided
into two parts. The light source units 101 are disposed on each of
the separated circuit boards 102, and the light source units 101
disposed on the different circuit boards 102 can be independently
controlled. A light source module of FIG. 23 includes a support 200
in the form of a chassis, and the light source units 101, the
circuit board 102, the optical sheet 103, the diffusion sheet 104,
and the luminance enhancement sheet 104 are provided in the
interior of the support 200. Also, a reflective part 201 may be
disposed on the circuit board 102 in order to induce light toward
the optical sheet 103. The reflective part 201 may also be employed
in the above-described embodiments.
[0106] Various additional exemplary embodiments of lens units, lead
frames, and wavelength conversion layers are described below with
respect to FIGS. 24-34. Features described with respect to these
embodiments may be utilized as described or may be incorporated
singularly or together into one of ore of the other embodiments
described herein.
[0107] FIGS. 24 and 25 illustrate an exemplary light source unit
101, including a lens unit 113. FIG. 24 is a schematic perspective
view of the light source unit 101. FIG. 25 is a cross sectional
view of the light source unit of FIG. 24, taken along line AA'.
Referring to FIGS. 24 and 25, a light emitting device package 100
according to an exemplary embodiment may include at least one light
emitting element 111, lead frames 112a and 112b, one of which has
the light emitting element 111 disposed on a surface thereof. The
surface on which the light emitting element 111 is disposed is a
rough surface so as to scatter at least a part of light emitted
from the light emitting element 111. The lens unit 113 comprises a
light-transmitting resin formed to cover at least a portion of the
lead frames 112a and 112b and the light emitting element 111, and a
surface of the lens unit 113 has a portion with a concave
shape.
[0108] Electrodes (not shown) formed on the light emitting element
111 may be wire bonded to the pair of the lead frames 112a and
112b, and may receive an electrical signal from the outside. The
light emitting element 111 may be wire bonded to each of the pair
of lead frames 112a and 112b through an anode formed on the light
emitting element 111. Alternately, the light emitting element 111
may be directly electrically connected with the one lead frame 112a
provided as a mounting area of the light emitting element 111,
without the use of a wire, and may be connected with the other lead
frame 112b through a conductive wire. Concrete connection methods
may be variously modified according requirements. While FIGS. 24
and 25 illustrate one light emitting element 111 included in one
light source unit 101, two or more light emitting elements 111 may
be included on one lead frame 112a or 112b.
[0109] The lens unit 113 may be formed on the upper surface of the
light emitting element 111 so as to cover the at least a portion of
the lead frames 112a and 112b and the light emitting element 111.
As long as the material forming the lens unit 113 is
light-transmitting, an ingredient thereof is not specifically
limited, and an insulating resin having light-transmitting
properties, such as a silicone resin composition, a modified
silicone resin composition, an epoxy resin composition, a modified
epoxy resin composition, an acrylic resin composition, or the like,
may be used. Further, a resin having superior weather resistance,
such as a hybrid resin or the like may be used, which includes at
least one of silicon, epoxy, and fluorine resins. The material of
the lens unit 113 is not limited to an organic material, and an
inorganic material having superior lightfastness, such as glass,
silica gel, or the like may be used therefor. In addition, the
surface shape of the lens unit 113 may be adjusted to allow for the
function of the lens, and particularly, to have a shape such as a
convex lens, a concave lens, an oval or the like, thereby
controlling light distribution.
[0110] When the lens unit 113 formed on a light emitting surface of
the light emitting element 111 has an upwardly projecting
hemispheric shape, a center area of the light emitting element 111
has the maximum level of luminance, while luminance is reduced
towards to the circumference of the light emitting element 111,
thereby having the form of a spot point light. Therefore, when a
plurality of light emitting elements are used to form a surface
light source, for example, used as the light source of light source
module 100, for example, attempts to uniformly diffuse light
incident from the light emitting element by disposing the diffusion
sheet 104 over the light emitting elements 111, and further, to
obtain a uniform surface light source by adjusting a distance
between the light source units 101 and the diffusion sheet 104 may
be made. However, the distance between the light source units 111
and the diffusion sheet 104 may be increased in order to obtain a
uniform luminance value across the diffusion sheet, and thus, the
thickness of a light source apparatus may be increased while
overall luminance may be reduced. Additionally, an optical sheet
103, as described herein may also be used.
[0111] The lens unit 113, formed to cover at least a portion of the
lead frames 112a and 112b and the light emitting element 111, has a
surface, a portion of which has a concave shape, whereby an
orientation angle of light emitted from the lens unit 113 may be
widened as compared to the light emitted from the light emitting
element 111, and a light distribution may be varied. Specifically,
as shown in FIGS. 24 and 25, the lens unit 113 may have a concave
portion 30b formed over the upper surface of the light emitting
element 111 and a convex portion 30a formed around the concave
portion 30b. The concave portion 30b may be formed in a center area
of the convex portion 30a in such a manner as to have a diameter
smaller than the maximum diameter of the convex portion 30a, and
the center points of the convex portion 30a and the concave portion
30b may be aligned with each other. In this case, the light
emitting element 111 may be disposed on the center line of the
convex portion 30a and the concave portion 30b.
[0112] In a case in which the lens unit 113 having a shape shown in
FIGS. 24 and 25 is provided, the maximum luminance value is shown
at a position spaced apart from the light emitting element 111 by a
predetermined distance, unlike in the case of a lens having an
upwardly projecting hemispheric shape. In particular, the brightest
area having a ring shape may be formed in a convex boundary portion
of the convex portion 30a and the concave portion 30b, and the next
brightest area may be formed around the center of the light
emitting element 111.
[0113] FIGS. 26(a) and 26(b) are diagrams, each schematically
illustrating a luminance distribution in an upper surface of a lens
unit including a convex portion and a concave portion formed within
the convex portion. FIG. 26(a) is a schematic diagram illustrating
the lens when viewed from above, and FIG. 26(b) is a schematic
diagram illustrating the lens when viewed from the side. Referring
to FIGS. 26(a) and 26(b), a light emitting element a is disposed
below an area A of a lens L shown in FIG. 26(a), a concave portion
is formed on the disposition area of the light emitting element a,
and the lens L has a bulged shape overall. In this case, as
mentioned above, since a high luminance value may be exhibited in
the disposition area A of the light emitting element and at a
position C formed to be spaced apart from the light emitting
element a by a predetermined distance, a dark portion having a ring
shape (hereafter, referred to as a dark ring) may be generated at a
boundary portion B between the area A and the position C.
[0114] The dark ring B, which may be evident as a result of the
lens unit 113 having convex and concave shapes, may be removed by
controlling the surface roughnesses of the lead frames 112a and
112b on which the light emitting element 111 is mounted, whereby
the light source unit 101 may have improved optical uniformity and
a wide orientation angle. The lead frames 112a and 112b may be
formed to have rough surfaces to thereby provide a surface light
source having improved optical uniformity by increasing the light
scattering rate at the surfaces of the lead frames 112a and
112b.
[0115] FIGS. 27(a) and 27(b), FIGS. 28(a) and 28(b) and FIGS. 29(a)
and 29(b), respectively show a diagram and a photograph explaining
a light distribution according to a surface roughness of a lead
frame. Referring to FIG. 27(a), in the case of a mirror surface
having a low level of surface roughness (a roughness on the nano
scale, less than several nm), it is in compliance with a reflection
law in which an incident angle and a reflection angle have the same
size. That is, an incident angle refers to an angle formed by a
direction of light with respect to a straight line (a normal)
perpendicular to a boundary surface, and a reflection angle refers
to an angle formed by a direction of light when the light is
reflected from the boundary surface to go on with respect to the
normal. In an ideal mirror surface, light incident on the surface
of a lead frame is reflected to have a reflection angle the same as
an incident angle, and no surface scattering is generated. FIGS.
28(a) and 28(b) show light distribution in the case of a surface
roughness on a submicron scale or less, and the light distribution
of reflected incident light has an internal reflection and a slight
scattering distribution. That is, a part of the incident light is
reflected and a slight scattering distribution occurs at the
surface of the lead frame. This scattering is referred to as
Gaussian scattering. Next, FIGS. 29(a) and 29(b) show light
distribution in the case of a surface roughness on a micron scale
or less. In this case, there is a low level of light distribution
within reflected light, and a light scattering distribution is
generated at the surface of the lead frame. This scattering is
referred to as Lambertian scattering.
[0116] The lead frames 112a and 112b may have a surface roughness
which generates Lambertian scattering as shown in FIGS. 29(a) and
29(b), and more particularly, prominences and depressions shown in
FIG. 29(a) may have a width of approximately 5 .mu.m. The surface
glossiness of the lead frames 112a and 112b may be numerically
expressed by using a GAM index. This is to indicate a value when
measuring the surface glossiness by using a photometer of GAM, Inc.
Light mirror-reflected (regularly reflected) from the surfaces of
the lead frames 112a and 112b is measured, thereby being
numerically expressed as having a value within the range of 0 to 4.
A regular reflection refers to a reflection generated on a
mirror-like smooth surface, and refers to the light reflected to
have a reflection angle the same as an incidence angle, as
described above. A GAM index, in a case in which all light is
scattered on a metal surface, without any of the light thereof
being regularly reflected is referred to as 0. A GAM index, in a
case in which all incident light is reflected is referred to as 4.
That is, closer to 0, a rougher surface is obtained, while closer
to 4, a smoother surface is obtained. Therefore, as a regular
reflection ratio increases, a ratio in which light is diffused and
reflected through scattering is reduced. The lead frames 112a and
112b may have a GAM index of approximately 0.4 to 1.0.
[0117] Referring to FIGS. 24 and 25, the lead frames 112a and 112b
may be provided as the mounting area of the light emitting element
111, and the at the same time, may act as a terminal for applying
an electrical signal supplied from the outside to the light
emitting element 111. To this end, the lead frames 112a and 112b
may be made of a metal material having superior electrical
conductivity, and a pair of the lead frames 112a and 112b may be
electrically insulated from each other. The surfaces of the lead
frames 112a and 112b may be plated with silver (Ag), gold (Au),
palladium (Pd), rhodium (Rh), or the like, in order to prevent the
corrosion of a metal.
[0118] The lead frames 112a and 112b may be subjected to a smooth
surface treatment in order to increase surface reflectance, thereby
enhancing luminance, and may be made of a highly reflective metal,
for example, silver (Ag), nickel (Ni), aluminum (Al), rhodium (Rh),
palladium (Pd), iridium (Ir), ruthenium (Ru), magnesium (Mg), Zinc
(Zn), platinum (Pt), gold (Au) or the like. However, as discussed
above, the surfaces of the lead frames 112a and 112b applied to the
bulged shaped lens unit including the concave portion may be
roughened to thereby increase a diffuse reflectance ratio thereof,
whereby a light source unit having a wide orientation angle without
a reduction of luminance may be provided.
[0119] FIGS. 30(a) and 30(b) show a radiation pattern and a
luminance distribution according to a GAM index of a lead frame in
a light emitting device package according to an exemplary
embodiment. FIG. 30(a) shows a radiation pattern according to a GAM
index, and FIG. 30(b) shows a luminance distribution according to a
GAM index. Referring to FIG. 30(a), `a` is a radiation pattern when
a GAM index is 1.2; `b` is a radiation pattern when a GAM index is
0.65; and c is a radiation pattern when a GAM index is 0.24. As
mentioned above, when a lens unit 113 having a concave portion 30b
in a center area of a convex portion 30a is provided, given that a
peak to peak angle representing the maximum luminance value is
referred to as an orientation angle, the orientation angle is
approximately 127.degree.. Here, when the lead frame has a smooth
surface (a GAM index is about 1.2, shown as a in FIG. 30(a)), a
relatively high value of luminance is exhibited in the upper
portion of the disposition area of the light emitting device,
rather than the circumferential area thereof, as indicated by a
shown in FIG. 30(a). Thus, a dark ring may be evident in the
circumferential area of the light emitting element. However, when
the diffusion reflectance ratio is increased by roughening the
surface of the lead frame, as compared to a regular reflection
ratio, luminance directly over the disposition area of the light
emitting element may be reduced such that the dark ring may be
removed, as indicated by b (a GAM index is 0.65) and c (a GAM index
is 0.24) shown in FIG. 30(a).
[0120] A light source unit according to an exemplary embodiment may
provide a substantially flat area having an almost uniform
luminance value, in the region of an reflection angle of 20.degree.
or less, based on the disposition area of the light emitting
element 111. In particular, when it is assumed that the maximum
luminance value in the light source unit 101 is 1, a luminance
value in the flat area may be in the range of approximately 0.29 to
0.34, and the value is almost uniformly maintained within the flat
area. With the flat area formed above the upper portion of the
light emitting element 111, the occurrence of the dark ring may be
inhibited, whereby the optical uniformity of the light source unit
101 may be improved.
[0121] A light emitting element package including a lens unit as
described may provide a luminance that is substantially flat within
a radiation angle range of about 20.degree. or less, with a maximum
luminance exhibited within a radiation angle range of about
50.degree. or more. An area of the light distribution pattern in
which a luminance is maintained to be substantially flat may have a
luminance value of 0.29 to 0.39, as compared to a maximum
luminance.
[0122] Referring to FIG. 30(b), the variation of a luminance
distribution according to a GAM index is illustrated. As for c, in
a case in which the surface of lead frame has the highest level of
smoothness, a luminance value is high. Referring to b, it can be
seen that the luminance value of b is barely different from that of
c, even though the GAM index is reduced to 0.65. However, in the
case of a, in which the GAM index is 0.24, the luminance value is
significantly lowered compared to that of c. Accordingly, in a case
in which the lead frame is allowed to have the GAM index in the
range of 0.4 to 1.0, the dark ring without the lowering of
luminance may be removed. In other words, the surface roughness of
the lead frame may be controlled in order to remove the dark ring
generated in by a lens unit having concave portion, provided on the
upper surface of the light emitting device to widen an orientation
angle, whereby optical uniformity and luminance may be improved.
Thus, the effect of reducing the thickness of the light source
module may be obtained in the case of using the light source unit
as the light source of a backlight unit.
[0123] FIG. 31 is a diagram illustrating a light source unit
according to another exemplary embodiment, when viewed from the
side. The light source unit of FIG. 31 includes a wavelength
conversion layer 40 provided on a light emitting surface of the
light emitting element 111, and having phosphor particles for
wavelength conversion. The wavelength conversion layer may have a
thickness of about 350 .mu.m or more. The phosphor may be made of a
fluorescent substance converting the wavelength of light into
yellow, red, or green light. The kinds of fluorescent substance may
be determined by a wavelength emitted from the active layer of the
light emitting element 111. In particular, the wavelength
conversion layer 40 may be made of a YAG, a TAG, a silicate, a
sulfide or a nitride fluorescent material. Specifically, a green
phosphor material may be at least one phosphor selected from the
group consisting of .beta.-SiAlON phosphor, MSiON phosphor
(MSi.sub.2O.sub.2N.sub.2:Eu, M is at least one of Sr, Ba and Ca),
GAL phosphor (Lu.sub.3Al.sub.5O.sub.12:Ce) and Silicate phosphor
(M.sub.2SiO.sub.4:Eu, M is at least one of Sr, Ba, Ca, Mg, Cl and
F). A red phosphor material may be at least one phosphor selected
from the group consisting of MSiAlN.sub.3:Eu (M is at least one of
Sr, Ba, Ca, Mg, Cl and F), M.sub.2Si.sub.5N.sub.8:Eu (M is at least
one of Sr, Ba, Ca, Mg, Cl and F) and
M.sub.1-yA.sub.1+xSi.sub.4-xO.sub.x+2yN.sub.7-x-2y:RE (M is at
least one of Ba, Sr, Ca and Mg, A is at least one of Al, Ga and B,
RE is at least one of rare earth metal, Y, La and Sc). A yellow or
orange phosphor may be at least one of phosphor selected from the
group consisting of .alpha.-SiAlON, YAG and
Ce.sub.zLa.sub.3-x-zCa.sub.1.5xSi.sub.6O.sub.yN.sub.11-y. By using
the green, red and phosphor material, a color reproduction can be
improved.
[0124] In addition, the wavelength conversion layer 40 may include
quantum dots. The quantum dot may be a nano crystal of a
semiconductor material having a diameter of approximately 1 to 10
nm, and may be a material exhibiting quantum confinement effects.
The quantum dots may convert the wavelength of light emitted from a
light emitting structure to thereby provide wavelength-converted
light, that is, fluorescence. For example, an Si nano crystal, a
group II-VI compound semiconductor nano crystal, a group III-V
compound semiconductor nano crystal, a group IV-VI compound
semiconductor nano crystal or the like may be used as a quantum
dot. Each of the nano crystals may be used separately, or a mixture
thereof may be used.
[0125] As for a quantum material, the group II-VI compound
semiconductor nano crystal may be any one selected from the group
consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe,
CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe,
CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe,
HggZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe,
HgZnSeS, HgZnSeTe and HgZnST. The group III-V compound
semiconductor nano crystal may be any one selected from the group
consisting of GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InAs, GaNP,
GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP,
GaAlNAs, GaAlPAs, GaInNP, GaInNAs, GaInPAs, InAlNP, InAlNAs, and
InAlPAs. The group IV-VI compound semiconductor nano crystal may
be, for example, SbTe.
[0126] The quantum dots may be dispersed in a dispersive medium,
such as a polymer resin in such a manner as to be naturally
dispersed therein. Any transparent medium may be used as the
dispersive medium of the wavelength conversion layer 40, as long as
it is not deteriorated by light or does not reflect light, will not
cause optical absorption, and will not substantially affect the
wavelength conversion function of the quantum dot. For example, an
organic solvent may include at least one of toluene, chloroform,
and ethanol, and the polymer resin may include at least one of
epoxy, silicon, polystyrene, and acrylate.
[0127] The radiation of a quantum dot may be generated during the
transfer of an electron in an excited state from a conduction band
to a valence band, and may exhibit characteristics in which
wavelength thereof is varied according to the size of particles of
a material, even in the case of the same material. Since light
having a short wavelength is emitted when the size of the quantum
dot is small, light of a desired wavelength region may be obtained
by adjusting the size of the quantum dot. In this case, the size of
the quantum dot may be adjustable by appropriately changing the
nano crystal growth conditions.
[0128] According to an aspect of an exemplary embodiment, if no
wavelength conversion layer 40 is used, wavelength conversion
members, such as phosphor particles or quantum dots may be
dispersed within the lens unit 113. The wavelength conversion
members may be uniformly mixed in the lens unit 113, and may
include quantum dots made of a YAG, a TAG, a silicate, a sulfide or
a nitride fluorescent material, or a Si nano crystal, a group II-VI
compound semiconductor nano crystal, a group III-V compound
semiconductor nano crystal or a group IV-VI compound semiconductor
nano crystal. In addition, an appropriate material, such as a
viscosity extender, a light diffusing agent, a pigment, a
fluorescent material, or the like may be added to the lens unit
113, as would be understood by one of skill in the art. The light
diffusing agent may favorably reflect light emitted from the light
emitting element 111 and the fluorescent material to thereby
inhibit a color unevenness by the fluorescent material having a
large particle diameter. Meanwhile, filler particles formed to have
a diameter of about 5 .mu.m to about 100 .mu.m are contained in the
lens unit 112, whereby the thermal shock resistance of the lens
unit 113 may be improved.
[0129] FIG. 33 shows a radiation pattern of a light emitting device
package according to a thickness of a wavelength conversion layer
thereof. FIG. 34 is a diagram schematically illustrating a
luminance distribution of the light emitting device package of FIG.
33. More particularly, with respect to identical lens units having
surfaces, portions of which are concave, in the case of variations
in the thickness of a wavelength conversion layer including a
phosphor, variations in radiation pattern and luminance
distribution are illustrated. Referring to FIGS. 33 and 34, when
the thickness of the wavelength conversion layer of the light
source unit is varied from 345 .mu.m to 500 .mu.m, it can be
confirmed that both an orientation angle and luminance are varied.
As the thickness of the wavelength conversion layer becomes
thicker, a peak to peak value in the radiation pattern is smaller
and a luminance value at the dark ring B' showing in the boundary
between the upper portion of the light emitting element and a peak
point is greater. As shown in FIG. 34, since the dark ring B'
showing in the boundary between the upper portion of the light
emitting element and the peak point may be rapidly reduced as a
luminance value is increased, whereby the dark ring B' may be
removed by controlling the thickness of the wavelength conversion
layer.
[0130] FIG. 32 is a diagram illustrating a backlight unit according
to an exemplary embodiment, when viewed from the side. Referring to
FIG. 32, a light source module 100 may include a number of light
source units 101, each including a light emitting element 111, a
package substrate 112 (or lead frames 112a and 121b) having a
surface on which the light emitting element 111 is disposed being a
rough surface so as to scatter at least a part of light emitted
from the light emitting element 111, and a lens unit 113 formed to
cover at least a portion of the package substrate 112 and the light
emitting device 111 and having a surface with a portion having a
concave shape. A substrate 300 having circuit wiring formed thereon
electrically connected with the light source units 101, and a
diffusion sheet 104 which uniformly diffuses light incident from
the light source units 101.
[0131] The substrate 300 on which the light source units 101 are
disposed may be a circuit board 102, and may be formed of an
organic resin material containing epoxy, triazine, silicon,
polyimide or the like and other organic resin materials, or may be
formed of a ceramic material such as AlN, Al.sub.2O.sub.3 or the
like, a metal material, or a metal compound material. In
particular, the substrate 300 may be a metal core printed circuit
board (MCPCB), a kind of metal PCB. However, the substrate 300 is
not limited to a PCB, and any substrate having wiring structures
formed on both surfaces thereof, namely a surface on which the
light source units 101 can be mounted and an opposite surface
thereto, the wiring structures provided for driving the light
source units 101, may be possible. Specifically, wirings for
electrically connecting each light source unit 101 may be formed on
a surface and an opposing surface of the substrate 300. A wiring
formed on the surface of the substrate 300 on which the light
source units are mounted may be connected to the other wiring
formed on opposing surface through a through hole, or a bump (not
shown).
[0132] In the direct type backlight unit using light emitting
elements, a light source module including the light emitting
elements or the like may be disposed below a liquid crystal panel,
and the light source module may directly illuminate the liquid
crystal panel. A diffusion sheet and an optical sheet, such a prism
sheet or the like may be disposed over or within the light source
module including a plurality of light emitting elements, whereby
light emitted from the light emitting elements may be uniformly
diffused. The diffusion sheet 104 may be a polyester substrate, and
may contain diffusing particles having a spherical or oval shape in
the diffusion sheet 104. These diffusing particles (not shown) may
be made of an acrylic resin, and may perform the diffusing and
mixing of light passing through the diffusion sheet 104.
[0133] In the light source module, luminance and optical uniformity
may be controlled by a distance between the diffusion sheet 104 and
the light source units 101. That is, as a height from the light
source units 101 (or the substrate 300 or circuit board 102 on
which they are disposed) to the diffusion sheet 104 is reduced and
a pitch between the light source units may be increased such that
optical uniformity may be degraded, whereby the dark ring between
the light emitting devices may be evident. According to an
exemplary embodiment, the light source units 101 in the light
source module may have a wide orientation angle, such that the
uniform surface light source may be obtained, with only a small
number of light source units, whereby an economical light source
module (or backlight unit including the same) may be obtained.
Further, a light source module (or a backlight including the same)
may be thinner and miniaturized because the distance between the
light source units 101 and the diffusion sheet may be
minimized.
[0134] Various additional exemplary embodiments of light emitting
element packages including features providing improved heat
emission efficiency and structural stability are described below
with respect to FIGS. 35-45. The light emitting element package may
be used as a light source unit as described above. Features
described with respect to these embodiments may be utilized as
described or may be incorporated singularly or together into one or
more of the other embodiments described herein.
[0135] FIG. 35 is a cross-sectional view of a light source unit
according to an exemplary embodiment, and FIG. 36 is a plan view of
the light emitting element package of FIG. 35 when viewed from
above. FIG. 37 is an enlarged view of a peripheral region of a
wavelength conversion unit and a conductive wire in the light
emitting element package shown in FIG. 35. Referring first to FIGS.
35 and 36, a light emitting element package 301 may include first
and second lead frames 112a and 112b. The packages may provide
electrical insulation. The first and second lead frames 112a and
112b may respectively have first and second principal surfaces S1
and S2. Each of the second principal surfaces S2 of the first and
second lead frames 112a and 112b may be exposed to the outside so
as not to be covered with a package body 116 with reference to FIG.
35. Accordingly, heat generated from a light emitting element 111
may be emitted to the outside through the first and second lead
frames 112a and 112b. For effective light emission, the first and
second lead frames 112a and 112b may be formed of a metal material
having a high level of electrical and heat conductivity. The light
emitting element 111 may be disposed on the first principal surface
S1 of the first lead frame 112a. As the light emitting element 111,
any device capable of emitting light in response to an electrical
current applied thereto may be employed, but a light emitting diode
may be used in consideration of light emission efficiency and the
miniaturization of the device or the like.
[0136] The light emitting element 111 may be electrically connected
with the first and second lead frames 112a and 112b to receive an
external electrical signal, and may include a conductive wire W to
be connected to the second lead frame 112b. Although FIG. 35
illustrates a case in which the light emitting element 111 is
electrically connected to the first lead frame 112a through an
electrode formed on a bottom of the light emitting element, the
light emitting element may also be connected to the first lead
frame 112a through a conductive wire W as in the case of the light
emitting device package 101 according to the exemplary embodiment
referred to in FIG. 38.
[0137] A wavelength conversion unit 117 adapted for use within the
package body 116 may include a light converting material converting
a wavelength of light emitted from the light emitting element 111,
and for example, may be formed of a mixture of a silicon resin and
a light conversion material. In this case, as the light conversion
material there may be provided, for example, a fluorescent
substance and a quantum dot. Light converted by the wavelength
conversion unit 117 may be mixed with light emitted from the light
emitting element 111, to provide white light in the light emitting
element package 301. The wavelength conversion unit 117 may not be
formed within the entire package body 116 that is formed of a
transparent molding resin, but may be formed limitedly in a
peripheral region of the light emitting element 111. Therefore, an
actual reduction effect on a light source area provided by the
light emitting element package 301 may be achieved, and the amount
of light emitted with regard to the area of a light source may
increase. As such, as the amount of light emitted with regard to
the light source area increases, the light emitting element package
301 may be appropriately used for illuminating devices requiring a
light source having a low etendue, such as a camera flash, an
automobile head lamp, a projector light source, or the like.
[0138] As the structure in which the wavelength conversion unit 114
is limitedly provided in a peripheral region of the light emitting
element 111, a trench structure T may be provided in the first
principal surface S1 of the first lead frame 112a, and on a
relatively protruded region defined by the trench structure T, that
is, in an inner area of the trench structure T, the light emitting
element 111 may be disposed. The wavelength conversion unit 117 may
be formed to cover the light emitting element 111 and a portion of
the conductive wire W may be limitedly provided to the protrusion
region. By the trench structure T formed on the vicinity of the
wavelength conversion unit 114, a shape of the wavelength
conversion unit 114 may be maintained by a surface tension even
before the hardening thereof, and the shape thereof may be for
example, a hemisphere. At this time, in order to maintain the shape
of the wavelength conversion unit 114, the shape of the conductive
wire W should be appropriately controlled. With reference to FIG.
37, for example, in a case that the conductive wire W is allowed to
serve as a support to maintain the shape of the wavelength
conversion unit 117, the conductive wire W is located at a
relatively low position as shown in a dotted line of FIG. 37; resin
contained in the wavelength conversion unit 117 provided before the
hardening may flow downward as shown in an arrow in the drawing,
such that it may be difficult to maintain a required shape of the
wavelength conversion unit 117.
[0139] To significantly reduce the occurrence of such defects, the
conductive wire W may need to be adapted such that a portion
thereof corresponding to an interface between the wavelength
conversion unit 117 and the package body 116 may not be directed
downward with reference to FIG. 37. Described in detail, a portion
of the conductive wire W that penetrates through the wavelength
conversion unit 117 and comes out of that may have a tilt that is
greater than 0.degree. and equal to or less than 180.degree., the
tilt being provided by the second principal surfaces S2 of the
first and second lead frames 112a and 112b. Accordingly, the resin
may not flow downwardly, and here, a portion of the conductive wire
directed downwardly of the second surface S2 may be defined as
having negative tilt. In addition, in the case of the conductive
wire W, a portion thereof provided externally of the wavelength
conversion unit 117 is bent downward at a position higher than a
height of the wavelength conversion unit 117, or a height of the
portion thereof becomes greater or is maintained up to a boundary
between the wavelength conversion unit 117 and the trench structure
T, that is, up to a start point of the trench structure T; an
effect of preventing resin from flowing downward may be increased.
Meanwhile, a shape of the trench structure T may be appropriately
selected depending upon a required shape of the wavelength
conversion unit 117, and the trench structure may be ring shaped.
Though FIG. 36 illustrates the circular-ring shaped wavelength
conversion unit 117 as an example, a polygonally-ring shaped
wavelength conversion unit may be applied.
[0140] The package body 116 may serve as a protector to protect
constitutive elements received therein, also function to fix the
first and second lead frames 112a and 112b, and be formed in an
upper part of the first principal surface S1 and between the first
and second lead frames 112a and 112b. A premolding method, that is,
a structure in which a reflective cup shaped package body is filled
with a transparent encapsulation material, is not required, but the
package body 116 may be filled with a material, i.e., a silicon
resin, an epoxy resin, or the like, having electrical insulation
and translucency. Accordingly, a manufacturing process may be
simplified and degradation of a premold as the package body which
may occur when the device operates may be prevented. In addition,
since factors generating a loss or distortion of light emitted from
the light emitting element 111 are not desired, a light efficiency
is prominent and a path distortion may not occur. It is illustrated
that the surface of the package body 116 has a flat structure, but
the package body 116 may have a lens shape as shown in the light
emitting element package 301 shown in FIG. 39, and the lens shape
may be formed on a path of light emitted from the light emitting
element 111.
[0141] FIG. 40 is a cross-sectional view of a light emitting
element package according to another exemplary embodiment. In the
same manner as the embodiment described above, the light emitting
element package 301 as shown in FIG. 40 may include first and
second lead frames 112a and 112b, a light emitting element 111, a
wavelength conversion unit 117, a conductive wire W, and a package
body 116. A partition structure 207 may be provided on a first
principal surface of the first lead frame 112a instead of the
trench structure. The wavelength conversion unit 117 may be formed
to be filled within the partition structure 207. The partition
structure 207 may be adapted to facilitate the formation of the
wavelength conversion unit 117. The partition structure 207 may be
formed of a material, for example, a resin that may be obtained
through a dispersion of white filler such as TiO.sub.2 or a metal
having a relatively high reflectivity, but it is not limited
thereto. The partition structure 207 may have a ring shape, for
example, be circularly or polygonally shaped, or be formed to have
other shapes.
[0142] FIG. 41 is a plan view of a light emitting device package
according to another embodiment. A light emitting element package
301, as shown in FIG. 41, may include first and second lead frames
112a and 112b, a light emitting element 111, a wavelength
conversion unit 117, a conductive wire W and a package body 116
similar to those shown and described with respect to FIG. 35. In
this embodiment, a trench structure T may be formed on the first
principal surface of the first lead frame 112a, but it is not
limited thereto. The light emitting element 111 and the wavelength
conversion unit 114 may be disposed on a protrusion region
protruding in the area of the trench structure T. The first and
second lead frames 112a and 112b may be formed to include
partially-removed shapes in end surfaces between first and second
principal surfaces as shown in FIG. 41, such that a contact area
between the first and second lead frames 112a and 112b and the
package body 116 may be increased to improve a bonding force
therebetween. Since a silicon resin has a relatively low mechanical
strength, a solution to improve the mechanical stability of the
light emitting element package 301 may be used, that is, an
increase in the contact area between the first and second lead
frames 112a and 112b and the package body 116 may be
undertaken.
[0143] In order to improve a mechanical strength of the light
emitting element package 301, the first lead frame 112a may have a
protrusion part formed thereon, and the second lead frame 112b may
have a recessed part into which the protrusion part may be
inserted. In detail, in the first lead frame 112a, one portion
thereof may protrude toward the second lead frame 112b, to form the
protrusion part. In the second lead frame 112b, one portion thereof
may be recessed to form the recessed part and receive the
protrusion part of the first lead frame 112a therein. Accordingly,
the first lead frame 112a may be "T" shaped while the second lead
frame 112b may be "U" shaped. In this case, the light emitting
element 111 may be disposed on a region of the protrusion part of
the first lead frame 112a. As such, an engagement structure for the
protrusion part and the recessed part of the first and second lead
frames 112a and 112b may be provided, thereby enhancing mechanical
stability and particularly stability against a bending moment
perpendicularly applied to the first and second principal
surfaces.
[0144] In order to improve the mechanical strength of the lead
frames, it may be desired to sufficiently secure the degrees of
engagement between the protrusion part and the recessed part by
appropriately controlling the size of the first and second lead
frames 112a and 112b and the size of the protrusion part and the
recessed part respectively provided therewith. In detail, a length
A of the first lead frame 112a may be greater than or equal to half
of the length L of the light emitting element package 301 on the
basis of a direction in which the protrusion part is formed as a
transverse direction in FIG. 41. In this case, the length A of the
first lead frame 112a may correspond to a distance from an end
surface thereof opposed to the protrusion part to an end of the
protrusion part. In a similar manner thereto, the length B of the
second lead frame 112b may be greater than or equal to half of the
length L of the light emitting element package 301. Further, in the
first and second lead frames 112a and 112b, a length C thereof, as
an overlapping portion of the protrusion part and the recessed
part, may be greater than or equal to a quarter of the length of
the light emitting device package.
[0145] FIG. 42 is a plan view of a light emitting element package
according to another exemplary embodiment, and FIG. 43 is a
schematic perspective view of first and second lead frames of the
light emitting element package shown in FIG. 42. With reference to
FIG. 42, a light emitting element package 301 may include first and
second lead frames 112a and 112b, a light emitting element 111, a
wavelength conversion unit 117, a conductive wire W and a package
body 116 in a similar structure to that described and illustrated
with respect to FIG. 41. A trench structure T may be formed in a
first principal surface of the first lead frame 112a, and the light
emitting element 111 and the wavelength conversion unit 117 may be
formed on the protrusion region relatively defined by the trench
structure T. Through holes h may be formed to penetrate through the
first and second principal surfaces of the first and second lead
frames 112a and 112b, and the package body 116 may be formed to
fill the inside of the through holes h. This structure may improve
a bonding force between the package body 116 and the first and
second lead frames 112a and 112b. The through holes h of the first
and second lead frames 112a and 112b may be formed in appropriate
positions, for example, in edge portions of the first and second
lead frames 112a and 112b, so as to obtain a stable combination
force with the package body 116.
[0146] In addition, since a bending moment may be applied to be
concentrated onto the respective peripheries of the protrusion part
and the recessed part of the first and second lead frames 112a and
112b, the through holes h may be formed on the respective
peripheries of the protrusion part and the recessed part. In this
case, at least one of the through holes h of the second lead frame
112b may be formed in a position of the second lead frame that has
a distance shorter than that of a position at which the through
hole h of the first lead frame is formed on the protrusion part
thereof, the distance being from one end surface of the first lead
frame 112a opposed to the end surface thereof having the protrusion
part formed therein. By this structure a mutually engagement force
effect between the through holes h of the protrusion part and the
through holes h of the recessed part may be improved.
[0147] In addition, a step coverage may be formed on the periphery
of the through holes h while forming the through holes h in the
first and second lead frames 112a and 112b, thereby increasing a
combination force thereof with the package body 116. With reference
to FIG. 43, on the second principal surfaces of the first and
second lead frames 112a and 112b, a step coverage may be formed on
a peripheral region of the through holes h, and the package body
116 may be formed on the region having the step coverage.
Accordingly, a contact area and a bonding force between the first
and second lead frames 112a and 112b and the package body 116 may
increase, such that the mechanical stability may be expected by the
through-holes h and step-coverage combined structure.
[0148] FIGS. 44 and 45 are respectively a plan view and a
cross-sectional view of a light emitting device package according
to another exemplary embodiment. With reference to FIGS. 44 and 45,
a light emitting element package 301 may include first and second
lead frames 112a and 112b, a light emitting element 111, a
wavelength conversion unit 117, a conductive wire W and a package
body 116. In a manner similar to that described and illustrated
above, a trench structure T may be formed in the first principal
surface of the first lead frame 112a, and the light emitting
element 111 and the wavelength conversion unit 117 may be formed on
a protrusion region defined by the trench structure T. An
insulation unit 507 may be formed on a region between the first and
second lead frames 112a and 112b to connect therebetween. In this
case, the insulation unit 507 may be formed of an oxide of a
material forming the first and second lead frames 112a and 112b.
For example, the first and second lead frames 112a and 112b may be
formed of Al and the insulation unit 507 may be formed of
Al.sub.2O.sub.3.
[0149] This structure may be obtained through an oxidization
process in which a portion of a plate shaped metal of Al or the
like is oxidized to be insulated in a thickness direction thereof
and then separated into two electrodes, lead frames, or more. In
this process case, the insulation unit 507 may have a shape in
which on the basis of a thickness direction of the first and second
lead frames 112a and 112b, a width of the insulation unit 507
narrows in a direction towards the inside of the insulation unit
507 from the surfaces thereof. Therefore, lead frames do not need
to be cut to form electrical separation therebetween or separately
arrange two lead frames or more, thereby providing a process
convenience. This insulation unit 507 may be expanded in volume due
to an oxidization reaction and may be easily damaged due to
external impacts according to the material properties thereof, but
according to this embodiment, a protrusion part and a recessed part
may be formed in lead frames to be engaged therebetween, thereby
significantly reducing a defect occurrence to obtain light emitting
device packages having increased mechanical strength and resistance
against external impacts.
[0150] As set forth above, in a light emitting element package
described herein, a heat emission performance may be improved so as
to significantly reduce a degradation of a resin part serving as a
package body, and a combination force between lead frames and a
package body may be increased to enhance structural
reliability.
[0151] As set forth above, according to exemplary embodiments, in a
light source module having a diffusion sheet, an optical distance
can be shortened and the number of light sources can be
reduced.
[0152] In addition, a backlight unit, a display apparatus, a
television set, and an illumination apparatus can have excellent
light uniformity while having a small thickness through the
utilization of the light source module.
[0153] While exemplary embodiments have been shown and described
herein, it will be apparent to those skilled in the art that
modifications and variations can be made without departing from the
spirit and scope of the invention as defined by the appended
claims.
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