U.S. patent application number 11/693597 was filed with the patent office on 2008-08-07 for light emitting diode assemblies for illuminating refrigerated areas.
Invention is credited to George K. Awai, Alain S. Corcos, Michael D. Ernst.
Application Number | 20080186695 11/693597 |
Document ID | / |
Family ID | 39675971 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080186695 |
Kind Code |
A1 |
Awai; George K. ; et
al. |
August 7, 2008 |
LIGHT EMITTING DIODE ASSEMBLIES FOR ILLUMINATING REFRIGERATED
AREAS
Abstract
An LED assembly for illuminating a refrigerated area includes a
plurality of LED modules and a reflector base configured to reflect
light generated by the plurality of LED modules into the
refrigerated area. The reflector base is further configured to
conduct heat away from the plurality of LED modules and also
includes a base cooling channel. Both the reflector base and the
plurality of LED modules are located substantially within the
refrigerated area. The LED assembly also includes an external heat
sink coupled to the reflector base, and configured to conduct heat
away from the reflector base, wherein the external heat sink is
further configured to be mounted substantially outside the
refrigerated area. The LED assembly can include a doom lens that
forms a doom cooling channel substantially enclosing the reflector
base. This internal heat sink includes an internal sink cooling
channel.
Inventors: |
Awai; George K.; (Danville,
CA) ; Ernst; Michael D.; (Alamo, CA) ; Corcos;
Alain S.; (Northridge, CA) |
Correspondence
Address: |
KANG LIM
3494 CAMINO TASSAJARA ROAD #436
DANVILLE
CA
94506
US
|
Family ID: |
39675971 |
Appl. No.: |
11/693597 |
Filed: |
March 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11670981 |
Feb 3, 2007 |
|
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|
11693597 |
|
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Current U.S.
Class: |
362/92 |
Current CPC
Class: |
F25D 2700/04 20130101;
G02B 6/0085 20130101; G02B 6/001 20130101; F25D 27/005
20130101 |
Class at
Publication: |
362/92 |
International
Class: |
F25D 27/00 20060101
F25D027/00 |
Claims
1. A light emitting diode (LED) assembly useful for illuminating a
refrigerated area, the LED assembly comprising: a plurality of LED
modules; a reflector base configured to reflect light generated by
the plurality of LED modules into the refrigerated area and is
further configured to conduct heat away from the plurality of LED
modules, wherein the reflector base includes a base cooling
channel, and wherein the reflector base and the plurality of LED
modules are configured to operate substantially within the
refrigerated area; and an external heat sink coupled to the
reflector base, and configured to conduct heat away from the
reflector base, wherein the external heat sink is further
configured to be mounted substantially outside the refrigerated
area.
2. The LED assembly of claim 1 further comprising a doom lens
forming a doom cooling channel substantially enclosing the
reflector base.
3. The LED assembly of claim 1 further comprising an internal heat
sink configured to be mounted substantially within the refrigerated
area and further configured to conduct heat from the reflector base
to the external heat sink and wherein the internal heat sink
includes an internal sink cooling channel.
4. The LED assembly of claim 1 wherein the external heat sink
includes an external sink cooling channel.
5. A light emitting diode (LED) assembly useful for illuminating a
refrigerated area, the LED assembly comprising: a plurality of LED
modules; a conductive base configured to conduct heat away from the
plurality of LED modules coupled to the conductive base, wherein
the conductive base includes a base cooling channel, and wherein
the conductive base and the plurality of LED modules are configured
to operate substantially within the refrigerated area; an external
heat sink coupled to the conductive base, and configured to conduct
heat away from the conductive base, wherein the external heat sink
is further configured to be mounted substantially outside the
refrigerated area; and wherein at least one of the plurality of LED
modules includes: an LED base; an LED located substantially within
the LED base and configured to generate a light beam; an inner beam
director; and an outer beam director, wherein an interface between
the inner beam director and the outer beam director is shaped to
refract and reflect the light beam along the interface, thereby
narrowing a substantial portion of the light beam.
6. The LED assembly of claim 5 wherein the LED has a geometrically
coated phosphor layer.
7. The LED assembly of claim 5 wherein the interface between the
inner beam director and the outer beam director includes an
intermediate beam director configured to further refract and
reflect the light beam generated by the LED.
8. The LED assembly of claim 5 wherein the shaped interface is
curved.
9. The LED assembly of claim 5 wherein the shaped interface is
highly reflective.
10. The LED assembly of claim 7 wherein the intermediate beam
director is highly reflective.
11. The LED assembly of claim 5 wherein the inner beam director has
a first N value and the outer beam director has a second N value,
and wherein the first N value is substantially lower than the
second N value.
12. The LED assembly of claim 5 further comprising a doom lens
forming a doom cooling channel substantially enclosing the
conductive base.
13. The LED assembly of claim 5 further comprising an internal heat
sink configured to be mounted substantially within the refrigerated
area and further configured to conduct heat from the conductive
base to the external heat sink and wherein the internal heat sink
includes an internal sink cooling channel.
14. The LED assembly of claim 5 wherein the external heat sink
includes an external sink cooling channel.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part application of U.S.
application Ser. No. 11/670,981, filed on Feb. 3, 2007, pending,
and entitled "Light Emitting Diode Modules for Illuminated Panels",
incorporated by reference in its entirety; and co-pending and
concurrently filed application Ser. No. ______, (Attorney Docket
No. IM 0702) filed Mar. 29, 2007, entitled "Light Emitting Diode
Waveguide Assemblies for Illuminating Refrigerated Areas", by
George K. Awai, Michael D. Ernst and Alain S. Corcos, which is
incorporated by reference herein for all purposes.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to illuminating panels.
More particularly, this invention relates to light emitting diode
(LED) modules for illuminating refrigerated areas.
[0003] Refrigerated display areas, such as supermarket freezers,
make use of interior case lighting to illuminate products and to
attract shoppers. In addition, the lighting should generate minimal
heat so as to reduce cooling requirements and avoid spoilage of the
displayed food.
[0004] Fluorescent lighting are commonly used and are mounted
vertically along the inside edge of the glass display doors of
refrigerated areas. Although fluorescent lighting generate less
heat and are more efficient than incandescent lighting, fluorescent
lighting suffer from decreased light output and reduced lamp life
when operated in cold temperature environments. Florescent lighting
also produces diffused light patterns and hence do not illuminate
the food products efficiently.
[0005] Recent attempts at replacing florescent lighting with LEDs
resulted in very limited success for several reasons. While the
compact size and durability of LEDs makes them suitable for compact
edge lighting for illuminated display doors, LEDs, especially
high-powered LEDs, generate a substantial amount of heat which
substantially increase cooling load of the refrigerated areas.
[0006] It is therefore apparent that an urgent need exists for LED
assembly/structures that are suitable for evenly and efficiently
illuminating refrigerated displays, and is easy to manufacturer,
easy to maintain, shock resistant, impact resistant, portable, cost
effective, and have long lamp-life.
SUMMARY OF THE INVENTION
[0007] To achieve the foregoing and in accordance with the present
invention, light emitting diode (LED) assemblies for illuminating
refrigerated display areas are provided. Such LED assemblies can be
operated very efficiently, cost-effectively and with minimal
maintenance once installed in the field.
[0008] In accordance with one embodiment of the invention, an LED
assembly provides illumination for a refrigerated area, the LED
assembly including a plurality of LED modules and a reflector base
configured to reflect light generated by the plurality of LED
modules into the refrigerated area. The reflector base is further
configured to conduct heat away from the plurality of LED modules
and also includes a base cooling channel. Both the reflector base
and the plurality of LED modules are located substantially within
the refrigerated area.
[0009] The LED assembly also includes an external heat sink coupled
to the reflector base, and configured to conduct heat away from the
reflector base, wherein the external heat sink is further
configured to be mounted substantially outside the refrigerated
area. The external heat sink can include an integral cooling
channel.
[0010] The LED assembly can include a doom lens that forms a doom
cooling channel substantially enclosing the reflector base. An
internal heat sink can also be mounted substantially within the
refrigerated area thereby conducting heat from the reflector base
to the external heat sink. This internal heat sink includes an
internal sink cooling channel.
[0011] In some embodiments, at least one of the plurality of LED
modules includes an LED base, an LED located substantially within
the LED base and configured to generate a light beam, an inner beam
director, and an outer beam director. The interface between the
inner beam director and the outer beam director is shaped to
refract and/or reflect the light beam along the interface, thereby
narrowing a substantial portion of the light beam into the
refrigerated area.
[0012] These and other features of the present invention will be
described in more detail below in the detailed description of the
invention and in conjunction with the following figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In order that the present invention may be more clearly
ascertained, one embodiment will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0014] FIG. 1 is a front view showing three illuminated doors for a
refrigerated space in accordance with the invention;
[0015] FIGS. 2A, 2B are a cross-sectional side view of one of the
illuminated wall pillars for the refrigerated area of FIG. 1 and
also shows display shelves;
[0016] FIGS. 3A-3D are cross-sectional views of several embodiments
of LED assemblies for the illuminated pillar of FIG. 2A;
[0017] FIG. 4 illustrates a variant of the embodiment shown in FIG.
3B;
[0018] FIGS. 5A-5C are cross-sectional views of additional
embodiments of LED assemblies for the illuminated pillar of FIG.
2A;
[0019] FIG. 6 illustrates a variant of the embodiment shown in FIG.
5B;
[0020] FIGS. 7A, 7B and 7C are an isometric view, a cut-away view
and a cross-sectional view, respectively, of an LED module 700 in
accordance with an aspect of the present invention;
[0021] FIGS. 7D, 7E are cross-sectional views of a substantially
reflective module and a refractive/reflective module in accordance
with the present invention;
[0022] FIGS. 8A-10E are cross-sectional views of additional
embodiments of the LED modules of the present invention; and
[0023] FIG. 11 is a cross-sectional view of another embodiment of
LED assembly for the illuminated pillar of FIG. 2A.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The present invention will now be described in detail with
reference to several embodiments thereof as illustrated in the
accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of the present invention. It will be apparent,
however, to one skilled in the art, that the present invention may
be practiced without some or all of these specific details. In
other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure
the present invention. The features and advantages of the present
invention may be better understood with reference to the drawings
and discussions that follow.
[0025] In accordance with the present invention, FIG. 1 is a front
view showing an illuminated refrigerated display area 100 with a
plurality of doors including doors 110, 120, 130. Door 110 includes
a transparent panel 112, a frame 114 and a door handle 116. For
clarity, doors 120, 130 are shown partially cut-away to expose a
support pillar 105 and a horizontal span 108.
[0026] FIG. 2A is a cross sectional side view showing pillar 105 of
FIG. 1 and also shows display shelves 210a, 210b . . . 210k
supported by corresponding brackets 215a, 215b . . . 215k. An LED
assembly 240 (described in greater detail below) is attached to the
refrigerated side of vertical pillar 105. LED assembly 240 can also
be coupled to an external heat sink 245 via heat pipes 248a, 248b,
248c, 248d . . . and 248m, thereby enabling LED assembly 240 to
dissipate heat outside the refrigerated area.
[0027] FIGS. 3A-3D are cross sectional views of exemplary
embodiments 300A, 300B, 300C, 300D for the LED assembly 240 of the
present invention, and correspond to cross section line 1A-1A of
FIG. 1. Referring first to FIG. 3A, LED assembly 300A includes doom
lens 310, reflector base 320a, LED boards 362, 364, internal heat
sink 350a, conductors 342, 344, 346 and external heat sink
340a.
[0028] Doom lens 310 is located substantially within the
refrigerated side of wall 330, while external heat sink 340a is
located on the ambient side of wall 330. Lens 310 can be made from
a suitable transparent or translucent material such as glass or a
suitable polymer, e.g., acrylic or polycarbonate. Depending on the
specific implementation, lens 310 can be clear or frosty. In
addition, lens 310 can have optical characteristics such as that of
a Fresnel lens which can be incorporated onto the protected inner
surface of lens 310.
[0029] Each LED boards 362, 364 includes a row of LED modules and
the circuitry for coupling the LED modules to a suitable power
source (not shown). Suitable LED modules are commercially available
from OSRAM Opto Semiconductors Inc. of Santa Clara, Calif., Nichia
Corporation of Detroit, Mich., Cree Inc. of Durham, N.C., or
Philips Lumileds Lighting Company of San Jose, Calif. LED boards
362, 364 may also include some of the power circuitry components
such as resistors and may also include sensors such as temperature
sensors and/or illumination level sensors.
[0030] LED boards 362, 364 are mounted on reflector base 320a which
focuses light rays 371a, 372a and rays 381a, 382a into rays 371b,
372b and rays 381b, 382b, respectively, onto the display area
located in the refrigerated side of wall 330.
[0031] Reflector base 320a which is coupled to internal heat sink
350a. Conductors 342, 344, 346 couple internal heat sink 350a to
external heat sink 340a through wall 330. As a result, the heat
generated by LED boards 362, 364 can be conducted from reflector
base 320a to internal heat sink 350a, and in turn to external heat
sink 340a via conductors 342, 344, 346.
[0032] In accordance with the present invention, the heat
dissipation capability of reflector base 320a and heat sinks 350a,
340a is further enhanced by lens cooling channel 315, base cooling
channel 325a and heat sink cooling channel 355a. As illustrated by
both FIGS. 1 and 2A, in this embodiment cooling channels 315, 325a,
355a are oriented vertically and hence are capable of efficiently
dissipating heat via air convection from ambient air drawn from
outside the refrigerated space, thereby substantially reducing the
amount of heat dissipated into the refrigerated space. Circulation
of cooling air can also be from forced air cooling. It is also
possible to divert some of the chilled air from the refrigerated
space into one or more of cooling channels 315, 325a, 355a. While
air is used as the exemplary cooling medium in this embodiment, it
is also possible to use other suitable fluids and gases known to
one skilled in the refrigeration arts such as Freon, R12 and
R134a.
[0033] FIG. 3B shows a variant 300B of the LED assembly 240, in
which the cooling surface area of heat sink cooling channel 355b is
substantially increased by introducing ribs or groves into the
internal surface of channel 355b thereby enhancing the heat
dissipating capability of LED assembly 300B and substantially
reducing the heat dissipated into the refrigerated space. In this
embodiment, ribs or groves can also be incorporated onto the
surface of external heat sink 340b to further increase the heat
dissipation capability of external heat sink 340b into the ambient
air.
[0034] Other modifications are also possible. For example, as shown
in FIG. 3C, light rays 371a, 372a, 381a, 382a produced by yet
another embodiment 300C of LED assembly 240 are focused into rays
371b, 372b, 381b, 382b, respectively, by a pair of curved
reflectors located on reflector base 320c. The shape and
orientation of these reflectors of base 320c can vary in accordance
to the width and depth of display shelves 210a, 210b . . . 210k. As
shown in FIG. 3D, in some implementations, LED assembly 300D can
have three LED boards 362, 364, 368.
[0035] Referring again to FIG. 1, it is also possible to mount any
one of LED assemblies 300A, 300B, 300C and 300D vertically along
the refrigerated side of door frame 114 and corresponding to cross
section line 1B-1B.
[0036] FIG. 4 is a cross sectional view of yet another embodiment
400 for the LED assembly 240 of the present invention, and
corresponds to section line 1C-1C of door frame 114. External heat
sink 440 is coupled to internal heat sink 350b via heat conducting
connectors 442, 444. In this embodiment, external heat sink 440
also includes a ribbed cooling channel 448. As a result, external
heat sink 440 is shaped to also function as a door handle which is
now warmer and more comfortable for a customer to use because
external heat sink 440 is now dissipating heat generated by LED
assembly 400.
[0037] Referring back to FIG. 1, instead of vertical mounting, LED
assemblies 300A, 300B and 300C can also be modified to operate in a
horizontal orientation along a top front span 108 of refrigerated
area 100 corresponding to section line 1E-1E, by for example
eliminating one of the LED board and also using forced air cooling.
This horizontal variant of LED assemblies 300A, 300B and 300C can
also be mounted along the top of door frame 114 corresponding to
section line 1D-1D.
[0038] Alternatively, as shown in FIG. 2B, it is also possible to
horizontally mount LED assemblies 242a, 242b . . . 242k, with each
LED assembly spanning vertical pillars, e.g., spanning pillar 105
and the adjacent pillar located between doors 110, 120, of
refrigerated area 100.
[0039] FIGS. 5A, 5B, 5C are additional cross sectional views of
additional variants 500A, 500B, 500C for exemplary vertical LED
assembly 240 and horizontal LED assemblies 242a, 242b . . . 242k in
accordance with the present invention.
[0040] Referring first to FIG. 5A, LED assembly 500A includes an
optical waveguide 510a, LED board 560, conductive base 545, thermal
barrier 535, external heat sink 540a and external cooling doom 520.
Waveguide 510a is located substantially within the refrigerated
side of wall 530, while the rest of assembly 500A, including
cooling doom 520, is located substantially on the ambient air side
of wall 530.
[0041] LED board 560 includes a row of LED modules and the
circuitry for coupling the LED modules to a suitable power source
(not shown). Suitable LED modules are commercially available from
OSRAM Opto Semiconductors Inc. of Santa Clara, Calif., Nichia
Corporation of Detroit, Mich., Cree Inc. of Durham, N.C., or
Philips Lumileds Lighting Company of San Jose, Calif. LED board 560
may also include some of the power circuitry components such as
resistors and may also include sensors such as temperature sensors
and/or illumination level sensors.
[0042] By repeatedly reflecting and refracting light rays generated
by LED board 560, waveguide 510a provides a pair of
evenly-illuminated and focused light beams into the refrigerated
area. For example, light ray 571a is internally reflected as light
ray 571b, which is refracted outside waveguide as light ray 571c
and also internally reflected as light ray 571d, and further
refracted and reflected into light rays 571e, 571f, respectively.
Light ray 571f is then refracted as light ray 571g and reflected as
light ray 571h, which in turn is refracted and reflected into light
rays 571k, 571m, respectively.
[0043] Similarly, light ray 572a is internally reflected as light
ray 572b, which is refracted outside waveguide as light ray 572c
and also internally reflected as light ray 572d, and further
refracted and reflected into light rays 572e, 572f, respectively.
Light ray 572f is then refracted as light ray 572g and reflected as
light ray 572h, which in turn is refracted and reflected into light
rays 572k, 572m, respectively.
[0044] LED board 560 is mounted on conductive base 545 which in
turn is coupled to external heat sink 450a. As a result, the heat
generated by LED board 560 can be conducted by base 545 to external
heat sink 540a, and then dissipated outside the refrigerated
area.
[0045] In accordance with the present invention, the heat
dissipation capability of heat sink 540a is further enhanced by
cooling channel 525 formed by external cooling doom 520. As
illustrated by both FIGS. 1 and 2, in this embodiment cooling
channel 525 is oriented vertically and hence is capable of
efficiently dissipating heat via air convection from ambient air
drawn from outside the refrigerated space, thereby substantially
reducing the amount of heat dissipated into the refrigerated space.
Circulation of cooling air can also be from forced air cooling. It
is also possible to divert some of the chilled air from the
refrigerated space into cooling channel 525.
[0046] FIG. 5B shows a variant 500B of the LED assembly 240, in
which the cooling surface area of heat sink 540b is substantially
increased by incorporating ribs or groves onto the surface of
external heat sink 540b thereby enhancing the heat dissipating
capability of LED assembly 300B and further reducing the heat
dissipated into the refrigerated space by LED board 530 and
waveguide 510a.
[0047] Other waveguide profiles are also possible and include
straight, tapered, and curved shapes and combinations thereof. For
example, as shown in FIG. 5C, waveguide 510c has a straight body
and a curved tip.
[0048] FIG. 6 is a cross sectional view of yet another embodiment
600 for the LED assembly 240 of the present invention, and
corresponds to cross section line 1C-1C of door frame 114. In this
embodiment, external heat sink 640 also includes a cooling channel
648 and is shaped as a door handle which is now warmer and more
comfortable for the customer's use because external heat sink 640
is now dissipating heat from LED board 560 via base 645.
[0049] In some embodiments, since white LEDs are not the most
efficient emitter of light, it is also possible for LED board 560
to transmit light in the substantially blue-to-ultraviolet range
into optical waveguides 510a, 510c that have been impregnated with
phosphors, enabling waveguides 510a, 510c to convert the
blue-to-ultraviolet light into white light or any colored light
within the visible spectrum.
[0050] FIGS. 7A, 7B and 7C are an isometric view, a cut-away view
and a cross-sectional view, respectively, of a highly efficient LED
module 700 in accordance with another aspect of the present
invention. LED module 700 includes a base 710, an outer beam
director 720, an inner beam director 730, and an LED 790.
[0051] Suitable materials for base 710 include high temperature
acrylic co-polymer and for beam directors 720, 730 include acrylic
and optical grade silicone. Depending on the application, beam
directors 720, 730 can be an optically clear material or slightly
diffusive. LEDs suited for LED 790 include commercially available
LEDs from OSRAM Opto Semiconductors Inc. of Santa Clara, Calif.
such as model numbers LW-E6SG, LW-G6SP and LW-541C.
[0052] Since most efficient LEDs typically generate substantially
more blue and ultraviolet light, LED 790 can be geometrically
coated with a suitable phosphor layer, also known as conformal
phosphor coating (not shown), known to one skilled in the art so as
to produce a compact LED capable of generating a whiter light beam
whose spectrum is better suited for illuminating display panels.
This is possible because an even phosphor coating minimizes
chromatic separation of the white light generated by LED 790. It is
also possible to use LEDs that generate a whiter light spectrum
without an additional phosphor layer.
[0053] While LEDs have been used for illumination applications,
most commercially available LED packages are designed to generate a
fairly wide-angled and evenly-spread beam of light for applications
such as area lighting. Hence, these off the shelf LED packages are
not suitable for edge illumination of display panels because a
wide-angled beam will generate a substantially higher level of
illumination closer to the edge of the display panels resulting in
uneven illumination.
[0054] In contrast, light sources for edge illumination of the
display panels should be capable of generating a substantially
narrow beam of penetrating light so as to evenly illuminate the
central portions of the display panels which can have a large
display surface area.
[0055] In accordance with one aspect of the present invention as
illustrated by FIG. 7C, the deep penetration needs are accomplished
primarily by reliance on the refractive and/or reflective
properties of the interface between outer beam director 720 and
inner beam director 730. The refractive and/or reflective
properties can be controlled by selecting suitable interface
profiles and N index values. Suitable profiles for beam director
interfaces include parabolic and elliptical curved shapes. Suitable
N values include for example, N1 being approximately 1.33 to 1.41
and N2 being approximately 1.49 to 1.6 for beam directors 720 and
730, respectively. In some embodiments, most of the light produced
by LED module 700 is substantially concentrated within an
approximately 40 degree beam angle.
[0056] Accordingly, exemplary light rays 760a, 770a produced by LED
790 are refracted by beam directors 720, 730 into rays 760b, 770b,
respectively. Light rays 760b, 770b are further refracted by the
external surface of outer beam director 720 into rays 760c, 770c,
and thereby enabling LED module 700 to generate a substantially
narrower beam of light than that initially produced by LED 790.
[0057] FIG. 7D shows a modified LED module 700D in which a
reflective layer 740 is added between outer beam director 720 and
inner beam director 730 thereby enhancing the reflective properties
of the interface between beam directors 720, 730. Reflective layer
740 can be formed by techniques well known in the art including
vapor and electrostatic deposition. Light rays 760a, 770a produced
by LED 790 are reflected by layer 740 into rays 760b, 770b,
respectively, enabling LED module 700D to produce a substantially
narrow and penetrating beam of light including rays 760c, 770c.
[0058] As discussed above, a substantially wide-angled beam will
better illuminate the surface of display panels closest to the
light source, while a substantially narrow light beam is especially
beneficial for deeper penetration of relatively large display
panels. At first blush, the shallow penetration and deep
penetration needs appear to be competing requirements.
[0059] In accordance with another aspect of the present invention
as illustrated by the cross-sectional view of FIG. 7E, both shallow
and deep penetration needs can be accomplished by reliance on a
suitable balance between the reflective and/or refractive
properties of the interface between outer beam director 720 and
inner beam director 730. This delicate refractive/reflective
balance can be controlled by selecting suitable materials with
suitable relative N values for directors 720, 730, e.g. N1 being
approximately 1.33 to 1.41 and N2 being approximately 1.49 to 1.6,
respectively.
[0060] For example, light ray 760 is refracted into ray 764b and
also reflected as ray 762b, while light ray 770 is reflected into
ray 774b and also reflected as ray 772b. Hence, LED module 700 is
now capable of producing a substantially narrow beam of light,
e.g., rays 762c, 772c, for penetrating the display panel while
still able to produce enough shorter range light rays, e.g., rays
764c, 774c to illuminate the closer surface of the display panel.
As a result, LED module 700 is capable of generating variable
intensity ranges at various beam angles, e.g., 80% intensity at
between 0 and 40 degrees, and 20% intensity between 40 to 80
degrees.
[0061] Several additions and modifications to LED module 700 are
also possible as shown in the exemplary cross-sectional views of
FIGS. 8A through 10E. Many other additions and modifications are
also possible within the scope of the present invention.
[0062] FIGS. 8A and 8B show embodiments 800A, 800B with
substantially straight interface profiles between outer beam
directors 820a, 820b and inner beam directors 830a, 830b,
respectively. Note the cone-shaped inner beam director 830a and
cylindrical-shaped inner beam director 830b.
[0063] FIGS. 9A-9C illustrate additional embodiments with multiple
refractive and/or reflective interfaces introduced by adding
intermediate beam directors, i.e., directors 932 of module 900A,
directors 934, 938 of module 900B, and director 932 of module 900C.
As discussed above, the multiple interfaces can have refractive
and/or reflective properties defined by suitable interface profiles
and N values.
[0064] For example, light rays 960a, 970a produced by LED 790 are
refracted by the interface between beam directors 930, 932 into
rays 960b, 970b, respectively. Light rays 960b, 970b are further
refracted by the external surface of intermediate beam director 932
into rays 960c, 970c.
[0065] Similarly, light rays 965a, 975a produced by LED 790 are
refracted by the interface between beam directors 932, 930 into
rays 965b, 975b, respectively, which are in turn further refracted
by the interface between beam directors 920, 932 into rays 965c,
975c. Light rays 965c, 975c are then refracted by the external
surface of outer beam director 920 into rays 765d, 775d.
[0066] As a result, a focused beam of light including exemplary
light rays 965d, 960c, 970c, 975d is formed, enabling LED module
900A to generate a substantially narrower and penetrating beam of
light than that initially produced by LED 790. As discussed above,
the balance between the refractive and/or reflective properties of
beam directors 920, 932, 930 can be controlled by selecting
suitable materials with suitable relative N values for directors
920, 932, 930. In addition, beam directors 920, 932, 930 can be
optically clear or slightly diffusive.
[0067] The cross-sectional views of FIGS. 10A-10E show additional
possible LED module embodiments, e.g., module 1000A without an
inner beam director; module 1000B with a concave-topped inner beam
director 1032; module 1000C with a convex-topped inner beam
director 1034; module 1000D has an exposed LED 790 and a
substantially reflective layer 1042 with a curved profile; and
module 1000E has an exposed LED 790 and a substantially reflective
layer 1044 with a cone-shaped profile.
[0068] FIG. 11 shows how the focused-beam LED modules described
above, e.g., LED modules 700, 800A, 800B . . . 1000E can be
incorporated into the LED assemblies 240 and 242a of the present
invention. In this example, LED boards 1162, 1164 each include at
least one focused-beam LED module, and hence LED boards 1162, 1164
can be mounted onto base 1120 of LED assembly 1100 without the need
for external reflectors. Depending on the application, it may also
be possible to combine focused-beam LED modules having different
beam angles onto LED boards 1162, 1164.
[0069] Many modifications and variations are possible. For example,
LED assemblies 300A, 300B, 300C, 400, 500A, 500B, 600, 1100 can be
dimmable by adding a variable current control circuitry. An
infrared red sensor can also be added to the control circuitry of
assemblies 300A, 300B, 300C, 400, 500A, 500B, 600, 1100 so that the
refrigerated area is illuminated when a potential customer enters
the detection field thereby dimming or turning on and off in an
appropriate manner.
[0070] Other modifications and variations are also possible. For
example, it is also possible to sense the ambient light level of
the surrounding and adjust the light output of the panels
accordingly, thereby conserving power. The present invention can
also improve the quality and quantity of light transmitted by other
non-point light sources such as neon and fluorescent light
sources.
[0071] In the above described embodiments, frame members of doors
110, 120 and the heat conducting components of LED assemblies 300A,
300B, 300C, 400, 500A, 500B, 600 can be manufactured from aluminum
extrusions. The use of any other suitable rigid and heat-conducting
framing materials including other metals, alloys, plastics and
composites such as steel, bronze, wood, polycarbonate,
carbon-fiber, and fiberglass is also possible.
[0072] In sum, the present invention provides improved LED
assemblies for evenly illuminating refrigerated areas that is easy
to manufacturer, easy to maintain, shock resistant, impact
resistant, cost effective, and have long lamp-life.
[0073] While the present invention has been described with
reference to particular embodiments, it will be understood that the
embodiments are illustrative and that the inventive scope is not so
limited. In addition, the various features of the present invention
can be practiced alone or in combination. Alternative embodiments
of the present invention will also become apparent to those having
ordinary skill in the art to which the present invention pertains.
Such alternate embodiments are considered to be encompassed within
the spirit and scope of the present invention. Accordingly, the
scope of the present invention is described by the appended claims
and is supported by the foregoing description.
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