U.S. patent application number 13/843649 was filed with the patent office on 2016-06-02 for one-piece multi-lens optical member and method of manufacture.
This patent application is currently assigned to CREE, INC.. The applicant listed for this patent is CREE, INC.. Invention is credited to Craig Raleigh, Kurt S. Wilcox.
Application Number | 20160153639 13/843649 |
Document ID | / |
Family ID | 51526297 |
Filed Date | 2016-06-02 |
United States Patent
Application |
20160153639 |
Kind Code |
A9 |
Raleigh; Craig ; et
al. |
June 2, 2016 |
One-Piece Multi-Lens Optical Member and Method of Manufacture
Abstract
An LED light fixture includes a heat-sink, a circuit board
thereon and having a plurality of spaced LED light sources, and a
one-piece optical member with a plurality of secondary lenses over
corresponding LED light sources, the one-piece optical member
comprises (a) each of the lenses having at least one layer of a
polymeric material which extends into a lens flange of such
material that surrounds the lens and is spaced from the other
lenses and (b) a polymeric carrier portion surrounding the lenses,
overlapping and molded onto to the lens flanges across such
overlapping, and extending to a peripheral edge. The polymeric
materials may be different; e.g., the lens layer and lense flanges
being an acrylic and the carrier being a polycarbonate. The
innermost lens layer may be of an LSR material. The invention is
also such one-piece optical member and a method of manufacturing
such member.
Inventors: |
Raleigh; Craig; (Racine,
WI) ; Wilcox; Kurt S.; (Libertyville, IL) |
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Applicant: |
Name |
City |
State |
Country |
Type |
CREE, INC.; |
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US |
|
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Assignee: |
CREE, INC.
Durham
NC
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Prior
Publication: |
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Document Identifier |
Publication Date |
|
US 20140268761 A1 |
September 18, 2014 |
|
|
Family ID: |
51526297 |
Appl. No.: |
13/843649 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13441571 |
Apr 6, 2012 |
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13843649 |
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12610077 |
Oct 30, 2009 |
8348461 |
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13441571 |
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Current U.S.
Class: |
362/244 ;
264/1.7; 362/326 |
Current CPC
Class: |
F21Y 2115/10 20160801;
F21V 5/007 20130101; F21Y 2105/10 20160801; B29C 45/1671 20130101;
F21V 5/04 20130101; B29L 2011/0016 20130101; F21K 9/60 20160801;
B29C 45/14467 20130101; B29D 11/00298 20130101; B29D 11/0073
20130101; F21Y 2113/00 20130101 |
International
Class: |
F21V 5/00 20060101
F21V005/00; B29D 11/00 20060101 B29D011/00; F21K 99/00 20060101
F21K099/00 |
Claims
1. In an LED light fixture including (a) a heat-sink structure
having a mounting surface, (b) a circuit board on the mounting
surface and having a plurality of LED light sources spaced thereon,
and (c) a one-piece optical member over the circuit board and
having a plurality of secondary lenses thereon each for alignment
with a corresponding one of the light sources, the improvement
wherein the one-piece optical member comprises: each of the lenses
having at least one layer of a polymeric material, which material
extends into a lens flange of such material that surrounds the lens
and is spaced from the lens flanges surrounding adjacent lenses;
and a polymeric carrier portion surrounding the lenses, overlapping
with and molded onto to the lens flanges across such overlapping,
and extending laterally therefrom to a peripheral edge portion.
2. The LED light fixture of claim 1 wherein the at least one lens
layer is of a first polymeric material and the carrier is of a
second polymeric material.
3. The LED light fixture of claim 2 wherein the first polymeric
material is an acrylic and the second polymeric material is a
polycarbonate.
4. The LED light fixture of claim 1 wherein the at least one lens
layer and the carrier are of the same polymeric material.
5. The LED light fixture of claim 1 wherein each lens has at least
two layers of polymeric material.
6. The LED light fixture of claim 5 wherein at least two of the
lens layers are of the same polymeric material.
7. The LED light fixture of claim 6 wherein the at least two lens
layers are of an acrylic.
8. The LED light fixture of claim 5 wherein at least two of the
lens layers are of the different polymeric materials.
9. The LED light fixture of claim 8 wherein one of the lens layers
is an acrylic and at least one other lens layer is of an LSR
material.
10. The LED light fixture of claim 5 wherein each lens has three
layers of polymeric material.
11. The LED light fixture of claim 10 wherein the three layers are
of the same polymeric material.
12. The LED light fixture of claim 10 wherein the innermost
polymeric layer is of an LSR material.
13. The LED light fixture of claim 5 wherein lenses each define a
lens optical footprint and at least one of the layers in each lens
is less than coextensive with the lens optical footprint.
14. The LED light fixture of claim 13 wherein another of the layers
includes a flange extending beyond the lens optical footprint.
15. A one-piece optical member comprising (a) a plurality of spaced
lenses, each of the lenses having at least one layer of a polymeric
material extending into a lens flange of such material that
surrounds the lens and is spaced from the lens flanges that
surround the adjacent lenses and (b) a polymeric carrier portion
surrounding the lenses, overlapping with and molded onto to the
lens flanges across such overlapping, and extending laterally
therefrom to a peripheral edge portion.
16. The one-piece optical member of claim 15 wherein the at least
one lens layer is of a first polymeric material and the carrier is
of a second polymeric material.
17. The one-piece optical member of claim 16 wherein the first
polymeric material is an acrylic and the second polymeric material
is a polycarbonate.
18. The one-piece optical member of claim 15 wherein the at least
one lens layer and the carrier are of the same polymeric
material.
19. The one-piece optical member of claim 15 wherein each lens has
at least two layers of polymeric material.
20. The one-piece optical member of claim 19 wherein at least two
of the lens layers are of the same polymeric material.
21. The one-piece optical member of claim 20 wherein the at least
two lens layers are of an acrylic.
22. The one-piece optical member of claim 19 wherein at least two
of the lens layers are of the different polymeric materials.
23. The one-piece optical member of claim 22 wherein one of the
lens layers is an acrylic and at least one other lens layer is of
an LSR material.
24. The one-piece optical member of claim 23 wherein the lens layer
of an LSR material is the innermost layer.
25. A method for manufacturing a one-piece optical member having
plural spaced lenses, the method comprising the steps of: providing
a plurality of lenses each of which has at least one layer of a
polymeric material extending into a lens flange of such material
that surrounds the lens; placing the plurality of lenses in spaced
positions of a mold for injection molding; and injection molding a
polymeric carrier portion of the one-piece optical member such that
the carrier portion surrounds the lenses, overlaps and is molded
onto to the lens flanges across such overlapping, and extends
laterally therefrom to a peripheral edge portion.
26. The method of claim 25 wherein the lenses have at least one
lens layer of a first polymeric material which material extends
into the lens flanges and the carrier is of a second polymeric
material.
27. The method of claim 26 wherein the first polymeric material is
an acrylic and the second polymeric material is a
polycarbonate.
28. The method of claim 25 wherein providing a plurality of lenses
further includes selecting lenses from a group of lenses having
different optical properties.
29. The method of claim 28 wherein the selected lenses all have the
same optical properties.
30. The method of claim 25 wherein each of the lens flanges has an
indexing feature and the placing of the lenses in spaced positions
further includes angularly orienting the lenses in the mold with
the indexing features.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to the field of LED (light
emitting diode) light fixtures and, more particularly, to secondary
lenses for such fixtures for directing light from LED light
sources, and, still more particularly, to polymeric secondary
lensing members for LED light fixtures.
BACKGROUND OF THE INVENTION
[0002] There is a need for lighting apparatus for a variety of
general lighting purposes which is low-cost and energy-efficient.
LED light sources are energy-efficient, and advances in LED
technology are providing even greater efficiencies over time. One
important aspect of LED light fixtures is the so-called secondary
lensing that directs light received from LED light sources. As used
herein, the term "LED light source" refers to an LED or a small
grouping of LEDs alone, or more typically to what is referred to as
an LED package--namely, an LED (or small grouping of LEDs) with a
what is referred to as a primary lens formed thereon. Secondary
lenses, which receive and direct light from LED light sources, are
of significant importance to LED light fixtures in many ways.
[0003] Secondary lenses play a major role, of course, in the
direction of light from a light fixture, and so determine to the
degree and spread of illumination, and overall optical efficiency.
The forming and shaping of secondary lenses are typically important
considerations with respect to the usefulness of an LED fixture,
and play a significant role in overall product cost. Improvements
in secondary lensing members, their optical capabilities, and their
manufacture are important considerations in the field of LED light
fixtures.
[0004] LED light fixtures for a wide variety of both specific and
general lighting applications typically have a plurality of LED
light sources, usually positioned in spaced relationship to one
another on a board (e.g., a circuit board), and a secondary lens is
aligned with each LED light source. Such secondary lenses are in
some cases part of a one-piece optical member that has a plurality
of secondary lens portions each surrounded by and interconnected by
a non-lens portion. Improvements in such multi-secondary-lens
members, the optical capabilities of the secondary lens portions,
and the manufacture of such members are important considerations in
the field of LED light fixtures. More specifically, speed (and
therefore cost) and accuracy of manufacture are particularly
important considerations.
[0005] With the rapid development of high-performance LED lighting
fixtures for a wide variety of general and specific lighting tasks
and with the varying requirements for secondary lensing in such
fixtures, there is a need for a system which enables quick and
accurate manufacture of one-piece optical members each having
different requirements for their secondary-lens portions.
[0006] It would be beneficial to provide secondary lensing,
one-piece multi-lens optical members, and LED light fixtures which
are low in cost as well as highly accurate in directing LED light,
and which contribute to the overall economy and efficiency of LED
light fixtures.
SUMMARY OF THE INVENTION
[0007] The present invention is an improved one-piece optical
member, secondary lensing, and LED light fixtures with such
secondary lensing, as well as a method of manufacturing such
one-piece optical members. These address the above-noted needs,
concerns and considerations and serve to improve product quality
and efficiency and reduce manufacturing costs of high-performance
LED light fixtures.
[0008] One aspect of this invention is an improved LED light
fixture of the type including (a) a heat-sink structure having a
mounting surface, (b) a circuit board that is on the mounting
surface and has a plurality of LED light sources spaced thereon,
and (c) a one-piece optical member over the circuit board and
having a plurality of secondary lenses thereon each for alignment
with a corresponding one of the light sources. In the improved LED
light fixture, the one-piece optical member comprises: each of the
lenses having at least one layer of a polymeric material, which
polymeric material extends into a lens flange of such material that
surrounds the lens and is spaced from the lens flanges that
surround adjacent lenses; and a polymeric carrier portion
surrounding the lenses, overlapping with and molded onto to the
lens flanges across such overlapping, and extending laterally
therefrom to a peripheral edge portion.
[0009] In certain embodiments, the at least one lens layer is of a
first polymeric material and the carrier is of a second polymeric
material. In some embodiments, the first polymeric material is an
acrylic and the second polymeric material is a polycarbonate. In
some other embodiments, the at least one lens layer and the carrier
are of the same polymeric material.
[0010] In some embodiments, each lens has at least two layers of
polymeric material. And, in some of such embodiments, at least two
of the lens layers are of the same polymeric material--e.g., an
acrylic.
[0011] In other embodiments, at least two of the lens layers are of
the different polymeric materials. In some of such embodiments, one
of the lens layers is an acrylic and at least one other lens layer
is of a cured liquid silicone resin (LSR). In some of these
embodiments, the lens layer of an LSR material is the innermost
layer. Use of an LSR later as the innermost layer tends to allows
excellent precision in the intended light-directing functions of
the lens portions of the unitary optic member, even while providing
time- and cost-related manufacturing advantages.
[0012] In certain embodiments of this invention, each of the lenses
has three layers has three layers of polymeric material. The layers
may be of the same polymeric material, or may be different. The
innermost polymeric layer may be an LSR material.
[0013] In the multi-layer lenses in this invention, each lens
defines a lens optical footprint and at least one of the layers in
each lens may be less than coextensive with the lens optical
footprint. As used herein, the term "lens optical footprint" means
the largest light-passage area within the lens and orthogonal to
the axis of the light source. In embodiments in which one of the
layers is less than coextensive with the lens optical footprint
cases, another of the layers may include a flange extending beyond
the lens optical footprint.
[0014] Another aspect of this invention is a one-piece optical
member of the type described above as a member of an LED light
fixture.
[0015] Still another aspect of this invention is a method for
manufacturing a one-piece optical member having plural spaced
lenses. The method comprises the steps of: providing a plurality of
lenses each of which has at least one layer of a polymeric material
extending into a lens flange of such material that surrounds the
lens; placing the plurality of lenses in spaced positions of a mold
for injection molding; injection molding a polymeric carrier
portion of the one-piece optical member such that the carrier
portion surrounds the lenses, overlaps and is molded onto to the
lens flanges across such overlapping, and extends laterally
therefrom to a peripheral edge portion.
[0016] In some embodiments of the method, the lenses have at least
one lens layer of a first polymeric material which material extends
into the lens flanges and the carrier is of a second polymeric
material. In some of such embodiments, the first polymeric material
is an acrylic and the second polymeric material is a
polycarbonate.
[0017] In some embodiments of the method, the step of providing a
plurality of lenses further includes selecting lenses from a group
of lenses having different optical properties. The group of lenses
may include subgroups, which flanged lenses of each subgroup having
the same optical properties but with optical properties differing
from group to group. The selecting steps may include selecting
lenses all of which have the same optical properties.
[0018] In certain embodiments, the flanges of each of the lenses
has an indexing feature and the step of placing the lenses in
spaced positions further includes angularly orienting the lenses in
the mold with the indexing features.
[0019] As used herein in referring to the optical member with its
plurality of spaced, flanged secondary lenses, the term "one-piece"
means that the portions of the carrier portion which surround the
lenses and overlap the lens flanges are overmolded onto such lens
flanges such that the layer-to-layer interface is bonded in the
overmolding process; and, for those optical members of this
invention for which the lenses have plural layers, the
layer-to-layer interfaces are bonded in overmolding as well.
[0020] As used herein, the term "innermost layer" refers to the
layer farthest from the LED light source, or at least the last
layer through which light from such light source passes. And the
term "outermost layer" refers to the layer closest to the LED light
source, or at least the first layer through which light from such
light source passes.
[0021] In descriptions of this invention, including in the claims
below, the terms "comprising," "including" and "having" (each in
their various forms) and the term "with" are each to be understood
as being open-ended, rather than limiting, terms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective view of an LED light fixture having
two one-piece optical members, such fixture and optical members
being in accordance with this invention.
[0023] FIG. 1A is a perspective view of a one-piece optical member
of the LED lighting fixture of FIG. 1.
[0024] FIG. 1B is an enlarged cross-sectional perspective view of
one portion of the one-piece optical member of FIG. 1A,
illustrating one secondary lens.
[0025] FIG. 1C is a perspective view illustrating the positioning
of secondary lenses as placed in injection-molding apparatus. The
injection-molding apparatus is not shown in FIG. 1C.
[0026] FIG. 2 is a perspective view of one such one-piece optical
member, showing its light-output side.
[0027] FIG. 3 is a perspective view of such optical member, but
showing its light-input side.
[0028] FIG. 4 is a plan view of such optical member.
[0029] FIG. 5 is a side sectional view taken along section 5-5 as
indicated in FIG. 4.
[0030] FIG. 6 is an end sectional view taken along section 6-6 as
indicated in FIG. 4.
[0031] FIG. 7 is an enlarged perspective view of the three
individual lenses of the one-piece optical member arranged as they
would be in a mold prior to the polymeric carrier portion being
injection molded onto the lens flanges, to complete the one-piece
optical member.
[0032] FIG. 8 is a central cross-sectional view of the lens of an
alternative embodiment, such alternative lens having three
layers.
[0033] FIG. 9 is an exploded perspective view of the lens of FIG.
18, serving to illustrate the shapes of the layers of such
lens.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0034] FIGS. 1 and 1A-1C illustrate an LED lighting fixture 10 in
accordance with this invention. LED light fixture 10 includes a
heat-sink structure 12 that has a mounting surface 12A on which a
circuit board 14 is mounted. Circuit board 14 has a plurality of
LED light sources 14A spaced thereon. A one-piece optical member 16
is positioned over circuit board 14 and has a plurality of
secondary lenses 20 thereon, each for alignment with a
corresponding one of light sources 14A.
[0035] In the improved LED light fixture, each of lenses 20 of
one-piece optical member 16 has a layer 22 of polymeric material,
which polymeric material extends into a lens flange 24 of such
material that surrounds lens 20 and is spaced from lens flanges 24
that surround adjacent lenses 20. One-piece optical member 16 also
has a polymeric carrier portion 26 surrounding lenses 20. Carrier
portion 26 overlaps with and is molded onto to lens flanges 24
across such overlapping, and carrier portion 26 extending laterally
therefrom to a peripheral edge portion 28. FIG. 1B best illustrates
the above-described characteristics.
[0036] The polymeric material of lens 20, i.e., the material of
outer layer 22 and flange 24, is an acrylic, while the polymeric
material of carrier portion 26 is a polycarbonate. A wide variety
of optical-grade acrylics can be used, and are available from
various sources, including: Mitsubishe Rayon America, Inc.; Arkema
Group; and Evonik Cyro LLC. Likewise, a wide variety of
polycarbonate materials can be used, and are available from various
sources, such as Bayer and Sabic.
[0037] FIG. 1C illustrates the positioning of secondary lenses 20
as placed in injection-molding apparatus (not shown). After such
placement, carrier portion 26 is injection molded onto lens flanges
24 to form one-piece optical member 16. As already indicated,
carrier portion 26 surrounds lenses 20 and overlaps and is molded
onto to lens flanges 24.
[0038] FIGS. 2-7 illustrate aspects of an alternative one-piece
optical member 16A which has three lenses 20 and a carrier portion
26A. The only significant difference between one-piece optical
members 16 and 16A is the number of lenses.
[0039] FIG. 7, as with FIG. 1C, illustrates the positioning of
secondary lenses 20 as placed in injection-molding apparatus.
Accurate placement into the injection-molding apparatus is
facilitated by indexing features in the form of posts 30 (see FIGS.
2, 4 and 5) which extend from lens flange 24 and mate with
corresponding recesses in the mold. (FIGS. 1A and 1B also show such
indexing feature.)
[0040] FIGS. 8 and 9 illustrate an alternative lens 40 which is a
multi-layer lens. Lens 40 has three layers, including an innermost
layer 42, an outermost layer 44, and an intermediate layer 46. The
layer shapes are illustrated in the FIG. 14 exploded view. As seen
well in FIGS. 8 and 9, lens 40 has an optical footprint, referred
to above, and innermost layer 42 is less than coextensive with the
lens optical footprint. Outermost layer 44 of lens 40 includes a
flange 48 extending beyond the optical footprint of lens 40.
[0041] The layers of each pair of adjacent layers of lens 40 are
joined together permanently at their interface by overmolding. Lens
40 may be formed by a series of injection-molding steps. For
example, innermost layer 42 is first formed by injection molding.
Then, at the next injection-molding station, intermediate layer 46
is overmolded with innermost layer 42. And then, at a third
injection-molding station, outermost layer 44 is overmolded onto
the previously overmolded layers.
[0042] The layers of lens 40 may be of the same or differing
polymeric materials. And injection-moldable materials may be chosen
having different indices of refraction. One or more of the lens
layers may be an acrylic and at least one other lens layer may be
of an LSR material. In particular, the innermost lens layer may be
an LSR material.
[0043] While the principles of this invention have been described
in connection with specific embodiments, it should be understood
clearly that these descriptions are made only by way of example and
are not intended to limit the scope of the invention.
* * * * *