U.S. patent application number 11/085534 was filed with the patent office on 2006-04-20 for dipolar side-emitting led lens and led module incorporating the same.
This patent application is currently assigned to Samsung Electro-Mechanics Co., Ltd.. Invention is credited to Hun Joo Hahm, Ho Seop Jeong, Joo Hee Jun, Hyung Suk Kim, Jin Ha Kim, Jin Jong Kim, Chon Su Kyong, Sang Hyuck Lee.
Application Number | 20060081863 11/085534 |
Document ID | / |
Family ID | 36179806 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060081863 |
Kind Code |
A1 |
Kim; Jin Ha ; et
al. |
April 20, 2006 |
DIPOLAR SIDE-EMITTING LED LENS AND LED MODULE INCORPORATING THE
SAME
Abstract
The present invention relates to a dipolar LED and a dipolar LED
module incorporating the same, in which an upper hemisphere-shaped
base houses an LED chip therein and adapted to radiate light from
the LED chip to the outside, and a pair of reflecting surfaces
placed at opposed top portions of the base in a configuration
symmetric about an imaginary vertical plane. The vertical plane
passes through the center of the LED chip perpendicularly to a
light-emitting surface of the LED chip. The reflecting surfaces are
extended upward away from the top portions of the base to reflect
light from the LED chip away from the imaginary vertical plane. A
pair of radiating surfaces are placed outside the reflecting
surfaces, respectively, to radiate light from the reflecting
surfaces to the outside. In this way, light emission from the LED
chip can be concentrated in both lateral directions.
Inventors: |
Kim; Jin Ha; (Sungnam,
KR) ; Hahm; Hun Joo; (Sungnam, KR) ; Kim;
Hyung Suk; (Suwon, KR) ; Kim; Jin Jong;
(Suwon, KR) ; Jun; Joo Hee; (Seoul, KR) ;
Lee; Sang Hyuck; (Suwon, KR) ; Kyong; Chon Su;
(Seoul, KR) ; Jeong; Ho Seop; (Sungnam,
KR) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, SUITE 1600
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
Samsung Electro-Mechanics Co.,
Ltd.
Suwon
KR
|
Family ID: |
36179806 |
Appl. No.: |
11/085534 |
Filed: |
March 21, 2005 |
Current U.S.
Class: |
257/98 ; 257/100;
257/99; 257/E33.059; 257/E33.071 |
Current CPC
Class: |
H01L 33/54 20130101;
H01L 33/60 20130101 |
Class at
Publication: |
257/098 ;
257/099; 257/100 |
International
Class: |
H01L 33/00 20060101
H01L033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2004 |
KR |
10-2004-0084120 |
Claims
1. A dipolar Light Emitting Diode (LED) lens comprising: an upper
hemisphere-shaped base housing an LED chip therein and adapted to
radiate light from the LED chip to the outside; a pair of symmetric
reflecting surfaces, each reflecting surface having a proximal end
placed on top of the base and a distal end extended upward and away
from the base, with the proximal ends of the reflecting surfaces
meeting each other in the form of a joint line on the top of the
base, forming a V-shaped valley extended along the joint line
between the reflecting surfaces, whereby light from the LED chip is
reflected by the reflecting surfaces in a dipolar pattern symmetric
about the joint line; and a pair of symmetric radiating surfaces
placed outside the reflecting surfaces, respectively, to radiate
light from the reflecting surfaces to the outside, thereby forming
a peanut-shaped light radiation pattern.
2. The dipolar LED lens according to claim 1, further comprising
triangular side surfaces confined by the reflecting surfaces, the
radiating surfaces and the base top portions.
3. The dipolar LED lens according to claim 1, wherein the
reflecting surfaces are curved downward.
4. The dipolar LED lens according to claim 1, wherein the
reflecting surfaces are curved upward.
5. The dipolar LED lens according to claim 1, wherein the
reflecting surfaces are planar.
6. The dipolar LED lens according to claim 1, wherein the
reflecting surfaces are widened as extending away from the base top
portions.
7. The dipolar LED lens according to claim 1, wherein the base has
a hemispheric space formed in a lower part thereof, the space being
opened downward at a uniform curvature.
8. A dipolar Light Emitting Diode (LED) module comprising: an LED
chip; a board mounted with the LED chip; a power-connecting unit
for electrically connecting the LED chip with an external power
source; and an LED lens for sealing the LED chip therein and
radiating light from the LED chip to the outside, wherein the LED
lens includes: an upper hemisphere-shaped base housing the LED chip
therein and adapted to radiate light from the LED chip to the
outside; a pair of symmetric reflecting surfaces, each reflecting
surface having a proximal end placed on top of the base and a
distal end extended upward and away from the base, with the
proximal ends of the reflecting surfaces meeting each other in the
form of a joint line on the top of the base, forming a V-shaped
valley extended along the joint line between the reflecting
surfaces, whereby light from the LED chip is reflected by the
reflecting surfaces in a dipolar pattern symmetric about the joint
line; and a pair of symmetric radiating surfaces placed outside the
reflecting surfaces, respectively, to radiate light from the
reflecting surfaces to the outside, thereby forming a peanut-shaped
light radiation pattern.
9. The dipolar LED module according to claim 8, wherein the base
has a hemispheric space formed in a lower part thereof, the space
being opened downward at a uniform curvature.
10. The dipolar LED module according to claim 9, further comprising
an encapsulant housing the LED chip within the space of the base
and integrally bonded with the LED chip, the encapsulant having a
curvature matching that of the space.
11. The dipolar LED module according to claim 10, wherein the
encapsulant comprises polymer having a refractive index of about
1.45 to 1.65.
12. The dipolar LED module according to claim 11, wherein the
encapsulant comprises nano-sized particles uniformly dispersed
through the polymer, the nano-sized particles having a refractive
index of about 2.2 to 3.5.
13. The dipolar LED module according to claim 10, wherein the lens
is provided as a separate piece from the encapsulant.
14. The dipolar LED module according to claim 8, further comprising
an encapsulant placed inside the lens to house the LED chip and
integrally bonded with the LED chip.
15. The dipolar LED module according to claim 14, wherein the
encapsulant comprises polymer having a refractive index of about
1.45 to 1.65.
16. The dipolar LED module according to claim 15, wherein the
encapsulant comprises nano-sized particles uniformly dispersed
through the polymer, the nano-sized particles having a refractive
index of about 2.2 to 3.5.
17. The dipolar LED module according to claim 8, wherein the LED
lens further includes triangular side surfaces confined by the
reflecting surfaces, the radiating surfaces and the base top
portions.
18. The dipolar LED module according to claim 17, wherein the base
has a hemispheric space formed in a lower part thereof, the space
being opened downward at a uniform curvature.
19. The dipolar LED module according to claim 18, further
comprising an encapsulant housing the LED chip within the space of
the base and integrally bonded with the LED chip, the encapsulant
having a curvature matching that of the space.
20. The dipolar LED module according to claim 17, further
comprising an encapsulant placed inside the lens to house the LED
chip and integrally bonded with the LED chip.
Description
RELATED APPLICATION
[0001] The present application is based on, and claims priority
from, Korean Application Number 2004-84120, filed Oct. 20, 2004,
the disclosure of which is hereby incorporated by reference herein
in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a Light Emitting Diode
(LED), and more particularly, to a dipolar LED structured to
concentrate light emission in both lateral directions and an LED
module incorporating the same.
[0004] 2. Description of the Related Art
[0005] According to the development of electronic devices, Liquid
Crystal Displays are gaining attention as next generation display
devices. Since an LCD does not light spontaneously, it is required
to provide a backlight unit for generating light in rear of an LCD
panel.
[0006] FIG. 1 is a cross-sectional view illustrating a Light
Emitting Diode (LED) lens disclosed in U.S. Pat. No. 6,679,621 as
an example of a conventional side-emitting LED used in the LCD
backlight unit.
[0007] Referring to FIG. 1, an LED lens 10 disclosed in the above
document includes an upper part having a reflecting surface I and a
refractive surface H and a lower part having a refractive surface
156. In a three dimensional view, the LED lens 10 is configured
symmetric about an optical axis 43.
[0008] In this LED lens 10, light generated from a focal point F is
radiated to the outside through the refracting surface H after
reflecting from the reflecting surface I or directly through the
refracting surface H.
[0009] However, the conventional LED lens 10 has following
drawbacks.
[0010] First, in an LED array including a plurality of LED lenses
10K, 10L, 10M, 10N and so on as shown in FIG. 2, when an LED lens
10L has a light radiation pattern or simply a light pattern
LP.sub.10 as shown in FIG. 2, a portion of light directly collides
against adjacent LED lenses 10K and 10M so that the adjacent LED
lenses 10K and 10M screen the light portion thereby forming blocked
areas BA.sub.10. The blocked area BA.sub.10 causes loss to light
emitted from the LED lens 10L. Then, the LEDs are necessarily
increased in number corresponding to the light loss by the blocked
areas BA.sub.10, thereby obstructing the miniaturization of the LCD
backlight.
[0011] Another problem of the conventional LED lens 10 will be
described with reference to FIG. 3.
[0012] As shown in FIG. 3, it is frequently required to increase
the size of an LED chip 2a over that of the existing LED chip 2 in
order to reduce current density thereby improving luminous
efficiency. However, light beams L2 generated in the periphery of
the LED chip 2a are out of total reflection condition and thus
emitted upward without reflecting from the reflecting surface I.
This disadvantageously lowers the color uniformity of an entire LCD
backlight module. Although the poor uniformity can be improved by
increasing the size of the LED lens 10, the increased LED lens size
also creates a problem of increasing the thickness of the LCD
backlight unit.
SUMMARY OF THE INVENTION
[0013] The present invention has been made to solve the foregoing
problems of the prior art, and it is therefore an object of the
present invention to provide a dipolar LED and an LED module
incorporating the same, by which when light beams are emitted from
an LED array having a plurality of LED lenses, light emission from
an LED chip can be concentrated mainly in both lateral directions
in order to prevent any blocked areas from being formed between
adjacent LED lenses.
[0014] It is another object of the invention to provide a dipolar
LED and an LED module incorporating the same which are structured
to concentrate light emission from an LED chip mainly in both
lateral directions in order to increase the size of the LED chip in
a direction substantially perpendicular to the concentrated light
emission thereby lowering current density in high power conditions
and thus improving luminous efficiency.
[0015] According to an aspect of the invention for realizing the
object, there is provided a dipolar LED lens comprising: an upper
hemisphere-shaped base housing an LED chip therein and adapted to
radiate light from the LED chip to the outside; a pair of
reflecting surfaces, placed at opposed top portions of the base in
a configuration symmetric about an imaginary vertical plane, which
passes through the center of the LED chip perpendicularly to a
light emitting surface of the LED chip, and extended upward away
from the top portions of the base, to reflect light from the LED
chip away from the imaginary vertical plane; and a pair of
radiating surfaces placed outside the reflecting surfaces,
respectively, to radiate light from the reflecting surfaces to the
outside.
[0016] The dipolar LED lens may further comprise triangular side
surfaces confined by the reflecting surfaces, the radiating
surfaces and the base top portions.
[0017] Preferably, the reflecting surfaces are curved downward,
upward or planar.
[0018] Preferably, the reflecting surfaces are widened as extending
away from the base top portions.
[0019] Preferably, the base has a hemispheric space formed in a
lower part thereof, the space being opened downward at a uniform
curvature.
[0020] According to another aspect of the invention for realizing
the object, there is provided a dipolar Light Emitting Diode (LED)
module comprising: an LED chip; a board mounted with the LED chip;
a power-connecting unit for electrically connecting the LED chip
with an external power source; and an LED lens as described above
for sealing the LED chip therein and radiating light from the LED
chip to the outside.
[0021] Preferably, the base has a hemispheric space formed in a
lower part thereof, the space being opened downward at a uniform
curvature.
[0022] The bipolar LED module may further comprise an encapsulant
housing the LED chip within the space of the base and integrally
bonded with the LED chip, the encapsulant having a curvature
matching that of the space.
[0023] Preferably, the lens is provided separate from the
encapsulant.
[0024] The bipolar LED module may further comprise an encapsulant
placed inside the lens to house the LED chip and integrally bonded
with the LED chip.
[0025] Preferably, any of the encapsulants comprises polymer having
a refractive index of about 1.45 to 1.65.
[0026] Preferably, any of the encapsulants comprises nano-sized
particles uniformly dispersed through the polymer, the nano-sized
particles having a reflective index of about 2.2 to 3.5.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0028] FIG. 1 is a cross-sectional view of a conventional LED
lens;
[0029] FIG. 2 is a plan view of an array of conventional LED lenses
for illustrating drawbacks of the LED lens;
[0030] FIG. 3 is cross-sectional and plan views of a conventional
LED lens for illustrating drawbacks of the LED lens;
[0031] FIG. 4 is a perspective view of an LED lens according to a
first embodiment of the invention;
[0032] FIG. 5 is a perspective view of the LED lens shown in FIG. 4
which is arranged in a different orientation;
[0033] FIG. 6 is a plan view of the LED lens shown in FIG. 4;
[0034] FIG. 7 is a front elevation view of the LED lens shown in
FIG. 4;
[0035] FIG. 8 is a side elevation view of the LED shown in FIG.
4;
[0036] FIG. 9 is a cross-sectional view of the LED lens shown in
FIG. 4 taken along the line IX-IX in FIG. 4 for illustrating
reflection and refraction in a cross-section of the LED lens;
[0037] FIG. 10 is a perspective view for illustrating reflection
and refraction in a lens wing of the LED lens shown in FIG. 4;
[0038] FIG. 11 is a plan view of the LED lens shown in FIG. 10;
[0039] FIG. 12 is a plan view illustrating a light pattern produced
by an LED lens of the invention;
[0040] FIG. 13 is a side elevation view of a first alternative to
the LED lens according to the first embodiment of the
invention;
[0041] FIG. 14 is a side elevation view of a second alternative to
the LED lens according to the first embodiment of the
invention;
[0042] FIG. 15 is a cross-sectional view of an LED module according
to a second embodiment of the invention;
[0043] FIG. 16 is a plan view of an LED array having a plurality of
LED lenses according to the invention; and
[0044] FIG. 17 is cross-sectional and plan views of an LED lens of
the invention for illustrating the enlargement of an LED chip.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0045] Preferred embodiments of the present invention will now be
described in more detail with reference to the accompanying
drawings.
[0046] FIG. 4 is a perspective view of an LED lens according to a
first embodiment of the invention, FIG. 5 is a perspective view of
the LED lens shown in FIG. 4 which is arranged in a different
orientation, FIG. 6 is a plan view of the LED lens shown in FIG. 4,
FIG. 7 is a front elevation view of the LED lens shown in FIG. 4,
and FIG. 8 is a side elevation view of the LED shown in FIG. 4.
[0047] Referring FIGS. 4 to 8, an LED lens 100 of the invention
comprises a unitary body made of transparent material, and includes
an upper hemisphere-shaped base 102 and a pair of opposite wings
104 projected from opposite top portions of the base 102.
[0048] The base 102 is generally shaped as a hemisphere to receive
an LED chip C therein while radiating light generated by the LED
chip C to the outside.
[0049] The wings 104 are configured symmetric about an imaginary
vertical plane that passes through the center of the LED chip C or
the base 102 and perpendicularly crosses a light emitting surface
or top surface of the LED chip C. In this case, the imaginary plane
102 generally crosses the underside of the base 102. In addition,
each of the wings 104 includes a reflecting surface 106 formed at
the top of the base 102 to outwardly reflect light incident from
the LED chip C in a direction substantially perpendicular to the
imaginary plane 112, a radiating surface 108 arranged outside the
reflecting surface 106 to outwardly radiate light reflecting from
the reflecting surface 106 and a pair of opposed side surfaces 110
formed between the reflecting surface 106 and the radiating surface
108.
[0050] The reflecting surface 106 is connected at the bottom with
the top of the base 102, and has an arc-shaped cross-section that
widens as extending to the top thereof. The radiating surface 108
is connected at the bottom with the top of the base 102, and has an
arc-shaped cross-section that widens as extending to the top
thereof. The radiation surface 108 is connected at the top with the
top of the reflecting surface 106. In this case, the top edges of
the reflecting and radiating surfaces 106 and 108 are slightly
curved downward as apparent from FIG. 8. The side surfaces 110 are
connected at the bottom with the top of the base 102, and extended
upward between the reflecting and radiating surfaces 106 and 108.
As the side surfaces 110 extend upward, the width of the side
surfaces 110 is reduced thereby defining a substantially triangular
area.
[0051] In the LED lens 100, the base 102 radiates light incident
directly from the LED chip C to the outside by refracting most
light. In the wings 104, the reflective surfaces 106 reflect most
light incident directly from the LED chip C toward the radiating
surfaces 108 so that the radiating surfaces radiate reflection
light to the outside by refracting most reflection light.
Accordingly, when light is generated from the LED chip C, a portion
of light spreads out radially through the base 102 but another
portion of light is spread out by the wings 104 in opposite
directions substantially perpendicular about both faces of the
imaginary vertical plane 112.
[0052] Such radiation of light through reflection and refraction
will be described in more detail with reference to FIGS. 9 to 11,
in which FIG. 9 is a cross-sectional view of the LED lens shown in
FIG. 4 taken along the line IX-IX in FIG. 4 for illustrating
reflection and refraction in a cross-section of the LED lens, FIG.
10 is a perspective view for illustrating reflection and refraction
in a lens wing of the LED lens shown in FIG. 4, and FIG. 11 is a
plan view of the LED lens shown in FIG. 10.
[0053] In description of the path of light generated from the LED
chip (not shown) in the LED lens 100 during the activation of the
LED, it is assumed for the convenience's sake that the LED chip is
a point light source designated with a focal point F and light is
generated entirely from the focal point F.
[0054] First, referring to FIG. 9, a group of light beams L1
generated from the focal point F within the LED lens 100 are
radiated through the outer surface of the base 102, and another
group of light beams L2 directed within a predetermined angle
.theta. with respect to the imaginary vertical plane 112 are
reflected from the reflecting surface 106 and then outwardly
radiated via the radiating surface 108. Through such refraction and
reflection, an overall light pattern is formed in a substantially
horizontal direction of the drawing.
[0055] Referring to FIG. 10, light beams L3 from the focal point F
are reflected from a horizontal line H11 on the right reflecting
surface 106, and then outwardly radiated through a horizontal line
H12 on the right radiation surface 108. Also, light beams L4 are
reflected from a horizontal line H21 on the left reflecting surface
106, and then radiated to the outside via the left radiating
surface 106.
[0056] When depicted in a plan view, as shown in FIG. 11, the light
beams L3 and L4 converge toward an axial line 114 that is
perpendicular to the imaginary vertical plane 112. That is, the
light beams emitted in various angles from the focal point F are
reflected from the reflecting surfaces 106 and then converge
generally toward the axial line 14 in opposite directions.
[0057] As a result, when the light beams L3 and L4 are emitted
upward within a predetermined angle range from the focal point F,
the wings 102 converge the light beams L3 and L4 toward the axial
line 114 so as to block or at least minimize the propagation of the
light beams L3 and L4 across the axial line 114.
[0058] Although not shown in the drawing, light beams directed
toward the wings 104 are incident onto the side surfaces 110 before
the reflecting surfaces 106. In this case, a portion of each side
surface 110 adjacent to the base 102 refracts a light beam toward
the axial line 114 along a nearby side surface 110 while radiating
the light beam to the outside. In addition, a portion of each side
surface 110 adjacent to each radiating surface 108 reflects a light
beam to the radiating surface 108 or to the reflecting surface 106,
from which the light beam is reflected again toward the radiating
surface 108. In this way, the light beam is radiated to the outside
via the radiating surface 108, refracted toward the axial line 114
along the side surface 110. Accordingly, it can be seen that the
light beams incident onto the side surfaces 110 are also redirected
toward the axial line 114.
[0059] Light refracted and reflected by the base 102 and the wings
104 as above makes a light pattern as shown in FIG. 12. As depicted
in the plan view of FIG. 12, when light beams radiate out through
the base 102, they are substantially refracted and uniformly spread
out making a circular light pattern LP1. On the other hand, light
beams reflected/refracted by the wings 104 converge to the axial
line 114 perpendicular to the imaginary vertical plane 112, thereby
making a dipolar light pattern LP2.
[0060] Accordingly, light from the LED chip (not shown) has a
higher density along the axial line 114 but a lower density along
the imaginary vertical plane 102 crossing the axial line 114,
thereby forming the dipolar light pattern LP2 as described
above.
[0061] FIG. 13 is a side elevation view of a first alternative to
the LED lens according to the first embodiment of the invention.
Referring to FIG. 13, an LED lens 200 is substantially the same as
the afore-described LED lens 100 of the first embodiment except
that a reflecting surface 206 is curved upward.
[0062] According to the reflecting surface 206 of this
configuration, when light beams are reflected from the reflecting
surface 206 as in FIGS. 10 and 11, they are more converged toward
an axial line (cf. the axial line 114) compared to the LED lens
100. Accordingly, the LED lens 200 produces a light pattern formed
longer along the axial line (cf. 114 in FIG. 12).
[0063] FIG. 14 is a side elevation view of a second alternative to
the LED lens according to the first embodiment of the invention.
Referring to FIG. 14, an LED 300 is substantially the same as the
LED lenses 100 and 200 except that a reflecting surface 306 is
formed substantially flat.
[0064] According to the reflecting surface 306 of this
configuration, when light beams are reflected from the reflecting
surface 306 as in FIGS. 10 and 11, they are more converged toward
an axial line (cf. the axial line 114) compared to the LED lens 100
but less than the first alternative LED lens 200. Accordingly, the
LED lens 300 produces a light pattern formed intermediating between
those of the LED lenses 100 and 200.
[0065] Alternatively, the LED lenses 100, 200 and 300 may have a
wing structure different from the above. For example, although the
wings have the reflecting surface, the radiating surface and the
side surfaces between the reflecting and radiating surfaces, the
reflecting surface may be suitably curved at both lateral edges to
directly connect with the radiating surface and vice versa to
realize the object of the invention.
[0066] An LED module of the invention may be realized by adopting
any of the LED lenses 100, 200 and 300 of the above structure. As
designated with dotted lines in FIG. 5, the LED module of the
invention includes an LED chip C contained within any of the LED
lenses 100, 200 and 300, a substrate S mounted with the LED chip C
and electric connectors W for electrically connecting the LED chip
C with an external power source (not shown). The LED module may
also include a reflector mounted on the substrate S for reflecting
light generated by the LED chip in an upward direction.
[0067] In addition, the LED module may further include an
encapsulant of a predetermined curvature to seal the LED chip
inside the LED lens 100, 200, 300. The encapsulant has a curvature
similar to, preferably, the same as that of the LED lens 100, 200,
300.
[0068] The encapsulant may be made of silicone. Alternatively, the
encapsulant may be made of polymeric material having a refractive
index of about 1.45 to 1.65, or contain nano-sized particles of a
higher refractivity material that is uniformly dispersed therein.
Suitable examples of the higher refractivity material may include
TiO.sub.2, ZrO.sub.2 and so on, in which TiO.sub.2 has a refractive
index of 3.1, and ZrO.sub.2 has a refractive index of 2.2. Such a
high refractivity material may change the refractivity of the
encapsulant up to about 1.7 to 2.5 when added into the polymeric
material. With raised refractivity as above, such an encapsulant
can prevent the degradation of light extraction efficiency caused
by a conventional encapsulant, in which the conventional
encapsulant reflects light from the LED chip owing to low
refractive index.
[0069] In addition, the encapsulant may be made utilizing polymer
chains bonded with inorganic material having high refractivity.
[0070] FIG. 15 is a cross-sectional view of an LED module according
to a second embodiment of the invention. The LED module shown in
FIG. 15 includes an LED 120 having a hemispheric encapsulant and an
LED diode lens 100A according to a second embodiment of the
invention for housing an upper portion of the LED 120. The LED lens
100A has a base 102a with a hemispheric space 102b formed therein
and wings 104 configured the same as those of the LED lens 100 of
the first embodiment. Accordingly, the LED lens 100A has a
structure substantially the same as that of the LED lens 100 except
for the hemispheric space 102b.
[0071] In the LED 120, the transparent encapsulant for sealing an
LED chip 122 therein has a refractive index similar to, preferably,
the same as that of the base 102a of the LED lens 100A. Although
not shown, the LED 120 includes a reflector for reflecting light
generated by the LED chip 122 in an upward direction, a substrate
mounting with the LED chip 122 and the reflector and electric
connectors for electrically connecting the LED chip 122 with an
external power source.
[0072] The encapsulant may be made of silicone. Alternatively, the
encapsulant may be made of polymeric material having a refractive
index of about 1.45 to 1.65, or contain nano-sized particles of a
higher refractivity material that is uniformly dispersed therein.
Suitable examples of the higher refractivity material may include
those as described about the LED of the first embodiment. In
addition, the encapsulant may be made utilizing polymer chain
bonded with inorganic material having high refractivity.
[0073] Since the LED lens 100A adopted in the LED 120 as above has
a structure the same as the afore-described LED lens 100 except
that the hemispheric space 102b is formed inside the LED lens 100A,
the LED lens 100A combined with an LED can realize functions and
effects the same as described about the LED lens 100. Accordingly,
the invention has an advantage in that those effects of the
invention can be also realized by capping a general LED with the
LED lens 100A.
[0074] The LED lens 100A is fabricated separate from an LED and can
be selectively separated/combined from/to the LED, and thus can be
conveniently applied thereto.
[0075] In the meantime, the LED lens 100A of this embodiment can be
modified to have the wing configurations of FIGS. 13 and 14 and
then capped on a conventional LED.
[0076] Alternatively, the LED lens 100A may have a wing structure
different from the above. For example, although each wing has a
reflecting surface, a radiating surface and side surfaces between
the reflecting and radiating surfaces, the reflecting surface may
be suitably curved at both lateral edges to directly connect with
the radiating surface and vice versa to realize the object of the
invention.
[0077] FIG. 16 is a plan view of an LED array having a plurality of
LED lenses according to the invention. The advantages of the
invention that can be found from FIG. 16 will be described with
reference to FIG. 12.
[0078] An LED array includes plurality of LED lenses 100K, 100L,
100M, 100N and so on of the invention are arranged into a specific
pattern. An LED lens 100L of this LED array has a substantially
elliptic light pattern LP.sub.100, which is extended along the
axial line 114 and shaped by combining the light patterns LP1 and
LP2 as shown in FIG. 12.
[0079] In the light pattern LP.sub.100 as above, a portion of the
light pattern directly collides against adjacent LED lenses 100M
and 100K, so that the LED lenses 100M and 100 screen the light
pattern portion thereby forming blocked areas BA100. However, since
the light pattern LP.sub.100 is shaped to extend along the axis
114, light quantity propagating toward the LED lenses 100M and 100K
is reduced compared to that of the conventional LED lenses 10 as
shown in FIG. 2. This as a result can reduce light loss by the
blocked areas BA100 to a large quantity compared to that by the
conventional blocked areas BA10 as shown in FIG. 2, thereby to
remarkably improve the efficiency of the entire LED array.
[0080] Then, since light quantity directed from one LED array
toward any adjacent LED array opposed thereto is increased, it is
possible to increase the distance between the LED arrays without
reducing resultant light quantity. This as a result can reduce the
number of LEDs used in an LCD backlight unit and thus the size of
the LCD backlight unit.
[0081] FIG. 17 is cross-sectional and plan views of an LED lens of
the invention for illustrating the enlargement of an LED chip. The
advantages of the invention which can be found from FIG. 17 will be
described in comparison with FIG. 3 above.
[0082] In case of high power LEDs, it is frequently required to
increase LED chip size over conventional one in order to reduce
current density thereby improving luminous efficiency.
[0083] In the prior art, when the LED chip 2a is enlarged, light
beams L2 generated from the periphery of the enlarged LED chip 2a
are out of total reflection condition even though the lens 156 is
increased in any directions. Then, the light beams L2 are radiated
upward without being reflected from the reflecting surfaces I.
[0084] However, in case of the LED lens 100 of the invention, the
problem of the prior art does not take place when an LED chip C2 is
enlarged along the vertical imaginary plane 112 from an LED chip
C1. That is, when the LED chip C2 is enlarged along the vertical
imaginary plane 112, enlarged chip portions (depicted with dotted
lines) have the same conditions as a conventional LED chip C1
portion with respect to the interface between the reflecting
surfaces 106. This as a result does not increase a probability of
light beams from the enlarged chip portions to be out of total
reflection condition and thus emitted upward than before the
enlargement. Therefore, applying the LED lens 100 of the invention
can increase the size of the LED chip C2 in order to lower current
density thereby improving luminous efficiency. At the same time,
this can prevent the size-enlargement of the LED lens 100 and
resultant thickness-increase of an LCD backlight module.
[0085] According to the dipolar LED and the LED module
incorporating the same of the invention as described above, when
light beams are emitted from an LED array having a plurality of LED
lenses, light emission from an LED chip can be concentrated mainly
in both lateral directions in order to prevent any blocked areas
from being formed between adjacent LED lenses.
[0086] Furthermore, since the dipolar LED and the LED module
incorporating the same can concentrate light emission from an LED
chip mainly in both lateral directions, an LED chip can be enlarged
in a direction substantially perpendicular to the concentrated
light emission thereby lowering current density in high power
conditions and thus improving luminous efficiency.
[0087] While the present invention has been shown and described in
connection with the preferred embodiments, 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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