Note: Descriptions are shown in the official language in which they were submitted.
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CA 02593720 2009-04-29
LOUVER :ALSSEMBLY FOR A LIGH"r FIXTURE
Field of the Invention
[00011 The field of this invention relates generally to lighting fixtures, and
more
particularly to a louver assembly for use therein.
Background
[0002] Fluorescent lighting has long been commonplace especially in
commercial,
institutional and industrial applications. The energy efficiency of
fluorescent fixtures coupled
with relatively low fixture costs cause fluorescent lighting to be the
lighting of choice in most
office situations as well as in numerous other task lighting applications. In
commercial
applications, overhead lighting systems are commonly found in buildings that
utilize
"dropped" or suspended ceiling grid arrangements, which are normally hung from
the floor
platforms of the story located immediately above. Typical overhead lighting
systems comprise
a light fixture housing, or troffer that is conventionally designed in the
shape of shallow,
inverted, rectangular box having one open face. A series of light fixture
housings or troffers
are usually installed in the dropped ceiling grid, with each troffer carrying
at least one light
source, such as a tubular lamp, therein.
[0003] Oftentimes, a transparent or translucent lens may be used to cover the
open face of
the light fixture housing. Such lenses can be undesirable if they are not
particularly designed
to effectively prevent the escape of low angle light rays from the light
fixture housings. These
low angle light rays may create a glare that can be irritating to those
individuals located in the
space that the overhead lighting systems are designed to illuminate.
[0004] Accordingly, the use of either coffers or louvers has been proposed in
the past for
eliminating or minimizing glare. Conventional coffers are rectangular recesses
formed in a
ceiling at spaced intervals that are designed to house the light fixture
housings. In order for a
coffer to effectively reduce glare, it must have deeper dimensions than the
light fixture
housings that it will contain because the light fixture housings are usually
installed in the upper
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01182.0049U2
surface or wall of the coffer, which allows the remaining side walls of the
coffer to act as
barriers to escaping low angle light rays. Though generally effective in
reducing glare, coffers
are often costly to install, and in certain instances, coffers may be
impossible to install if the
architectural design of the building prevents it.
[0005] Louvers help to reduce glare by directing the light radiating from the
troffer
generally downwardly. A typical louver comprises a grid-like structure that
includes a series
of V-shaped or parabolic shaped blades (or baffles) arranged perpendicular to
one another and
interlocked to form a series of more or less equally sized square or
rectangular openings.
Generally, louvers are mounted directly beneath the lighting tubes of light
fixture housings, or
troffers, such that the bottom edge of the louver is more or less flush with
the plane of the
ceiling.
[0006] A louver is typically assembled from a series of lateral and
longitudinal metal
blades. It has also been known to fabricate single-piece, plastic louvers
using conventional
injection molding techniques. Plastic louvers may be undesirable, however,
because of
deterioration that can result due to the louver blades proximity to light
sources that generate
substantial amounts of heat. Whether metal or plastic, the blades of most
louvers are typically
designed with parabolic side wall surfaces that are shaped to reflect the
light emitted from the
lamps downward in an effort to minimize the escape of the low angle light rays
that produces
glare. Typically, in order to create the parabolic shape for the blade side
wall, the top edge
surface of the blade is wider than the lower edge surface. This wide area
along the blade upper
edge surface acts to block a portion of the light emitted from the light
source, i.e., lamp, and
reflects it back into the light fixture, which negatively impacts the light
fixture efficiency.
[0007] Louvered troffers generally set the standard in architectural lighting
for most
commercial and institutional applications and have become essential components
of the very
architecture of high activity environments. Thus, it is desirable to provide
louvered fixtures
which can be manufactured at minimum cost yet exhibit exceptionally high
performance and
provide a visually aesthetic appearance in their operating environment.
Further, these low-cost,
high performance louvered fixtures must be rapidly installable and must yield
ever-increasing
energy efficiencies while producing desired illuminance levels. Contemporary
lighting
systems and particularly louvered troffer systems must therefore provide a
marriage of
aesthetics and performance at minimum manufacturing costs.
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SUMMARY
[0008] In response to the difficulties encountered in the prior art, a louver
assembly is
disclosed for use in an overhead lighting system. The louver assembly is
disposed within a
light fixture housing, just below one or more light sources, such as a tubular
lamp. In one
aspect, the louver assembly focuses the light radiated from the tubular
lamp(s) in a downward
direction.
[0009] In one embodiment, a plurality of blade ribs and a plurality of
stringers are
arranged perpendicular to one another to comprise the louver assembly. In one
aspect, the
stringers extend in the longitudinal direction, while the blade ribs extend in
the transverse
direction. The ribs and stringers are interconnected in a quick, easy, and
secure manner to
form the exemplified louver of the present invention.
[00010] Other apparatus, methods, and aspects and advantages of the invention
will be
discussed with reference to the Figures and to the detailed description of the
preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[00011] The accompanying drawings, which are incorporated in and constitute a
part of this
specification, illustrate several aspects described below and together with
the description, serve
to explain the principles of the invention. Like numbers represent the same
elements
throughout the figures.
[00012] FIG. 1 is a perspective view of a louver assembly of the present
invention shown
disposed within a light fixture housing that is configured for mounting two
lamp sources
according to a first embodiment of the invention.
[00013] FIG. 2 is a bottom elevational view of the louver assembly of Fig. 1,
shown
disposed within the light fixture housing.
[00014] FIG. 3 is a partial broken cross-sectional view of the louver assembly
of Fig. 2,
taken across line 3-3 of Fig. 2.
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[00015] FIG. 4 is a bottom end perspective view of the louver assembly of Fig.
1.
[00016] FIG. 5 is a top end perspective view of the louver assembly of Fig. 1.
[00017] FIG. 6 is a top side perspective view of the louver assembly of Fig.
1.
[00018] FIG. 7 is a perspective view of a louver assembly of the present
invention shown
disposed within a light fixture housing that is configured for mounting two
lamp sources
according to a second embodiment of the invention.
[00019] FIG. 8 is a bottom elevational view of the louver assembly of Fig. 7,
shown
disposed within the light fixture housing.
[00020] FIG. 9 is a perspective view of a louver assembly of the present
invention shown
disposed within a light fixture housing that is configured for mounting two
lamp sources
according to a third embodiment of the invention.
[00021] FIG. l0A is a perspective view of an exemplary blade rib of the louver
assembly of
Fig. 9, showing a rolled lower edge configured to increase the structural
rigidity of the blade
rib.
[00022] FIG. lOB is an enlarged perspective view of an end of the blade rib of
Fig. 10A,
showing the rolled lower edge.
[00023] FIG. lOC is an enlarged perspective view of a center portion of the
blade rib of Fig.
IOA, showing a notch defined in a portion of the rolled lower edge of the
blade rib
[00024] FIGS. 11A-11J are cross-sectional views of exemplary blade ribs of the
louver
assembly shown in Fig. 8A, showing alternative embodiments of the rolled lower
edge of the
blade rib.
[00025] FIGS. 12A-12J are cross-sectional views of exemplary blade ribs of the
louver
assembly, showing alternative embodiments of the rolled upper edge of the
blade rib.
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DETAILED DESCRIPTION OF THE INVENTION
[00026] The present invention can be understood more readily by reference to
the
following detailed description, examples, drawing, and claims, and their
previous and
following description. However, before the present devices, systems, and/or
methods are
disclosed and described, it is to be understood that this invention is not
limited to the specific
devices, systems, and/or methods disclosed unless otherwise specified, as such
can, of course,
vary. It is also to be understood that the terminology used herein is for the
purpose of
describing particular aspects only and is not intended to be limiting.
[00027] The following description of the invention is provided as an enabling
teaching of
the invention in its best, currently known embodiment. To this end, those
skilled in the
relevant art will recognize and appreciate that many changes can be made to
the various
aspects of the invention described herein, while still obtaining the
beneficial results of the
present invention. It will also be apparent that some of the desired benefits
of the present
invention can be obtained by selecting some of the features of the present
invention without
utilizing other features. Accordingly, those who work in the art will
recognize that many
modifications and adaptations to the present invention are possible and can
even be desirable in
certain circumstances and are a part of the present invention. Thus, the
following description
is provided as illustrative of the principles of the present invention and not
in limitation
thereof.
[00028] As used throughout, the singular forms "a," "an" and "the" include
plural referents
unless the context clearly dictates otherwise. Thus, for example, reference to
"a blade rib" can
include two or more such blade ribs unless the context indicates otherwise.
[00029] Ranges can be expressed herein as from "about" one particular value,
and/or to
"about" another particular value. When such a range is expressed, another
aspect includes
from the one particular value and/or to the other particular value. Similarly,
when values are
expressed as approximations, by use of the antecedent "about," it will be
understood that the
particular value forms another aspect. It will be further understood that the
endpoints of each
of the ranges are significant both in relation to the other endpoint, and
independently of the
other endpoint.
CA 02593720 2007-06-22
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[00030] As used herein, the terms "optional" or "optionally" mean that the
subsequently
described event or circumstance may or may not occur, and that the description
includes
instances where said event or circumstance occurs and instances where it does
not.
[00031] As used herein, the term "light fixture housing" may be used
interchangeably
throughout the specification with troffer, light fixture, light housing,
fixture, luminaire, or
housing, as is known in the art.
[00032] A louver assembly 10 is disclosed herein for use with an overhead
lighting system
in order to greatly reduce glare when illuminating commercial, office,
institutional, or
industrial spaces. Referring now to the drawings, and in particular to Figures
1-6, a first
embodiment of the louver assembly 10 is mounted within a conventional light
fixture housing
2, such that the bottom edges of both the louver assembly 10 and the light
fixture housing 2 are
more or less flush with one another, as well as with the plane of a ceiling
(not shown). At least
one light source, such as the exemplified pair of substantially parallel
elongate tubular light
lamps, are mounted to a base 5 of the light fixture housing and are disposed
between the light
fixture housing 2 and the louver assembly 10. However, it is contemplated that
any
conventional light sources can also be used, such as, without limitation, high
lumen output
electronic systems. In one aspect, the louver assembly of the present
invention allows for the
use of high lumen output electronic systems that would normally exhibit a loss
of efficiency
because of thermal effects on fluorescent output with traditional lensed
troffer lighting fixtures.
Further, it is contemplated that the exemplified louver assembly 10 can be
configured, as one
skilled in the art will appreciate, to accommodate one, two, three, or more
elongated light
sources 4 such as the exemplified tubular fluorescent lamps depending on the
lighting
performance desired or the size of the light fixture housing 2.
[00033] In one aspect, a plurality of blade ribs 20 and a plurality of
stringers 40 are
arranged perpendicular to one another to comprise the louver assembly. In one
aspect, the
stringers extend in the longitudinal direction, while the blade ribs extend in
the transverse
direction. In one exemplary aspect, the ribs and stringer can be
interconnected in a quick, easy,
and secure manner to form the exemplified louver of the present invention.
[00034] In one exemplified aspect, the louver assembly 10 comprises a door
frame 12, the
plurality of blade ribs 20 and the plurality of stringers 40, which are
arranged perpendicular to
one another to form a series of more or less equally-sized square or
rectangular openings. In
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one aspect, the door frame comprised a plurality of elongate support members
14 that are
connected together conventionally. In the illustrated example, four support
members are
connected together to form the generally rectangular door frame shown in
Figures 1-6. Further,
the louver assembly 10 can comprise a plurality of spring clips 16 that can be
attached to edge
portions of the support member forming the door frame. The spring clips are
conventional and
are configured so that the door frame can be releaseably connected to the
light fixture housing.
Of course, it is contemplated that other conventional means for releaseably
securing the louver
assembly of the present invention to the light fixture housing, such as
screws, bolts, and the
like, can be used.
[00035] In the exemplary embodiment illustrated in Figures 1-6, the plurality
of blade ribs
20 comprises two end blade ribs 22 and six center blade ribs 24. In one
aspect, each of the end
blade ribs and center blade ribs can be substantially identical to each other.
Further, each blade
rib 20 has a lower edge 26 and an opposed upper edge 28 that is configured to
be positioned
proximate a portion of the base 5 of the light fixture. In one aspect, the
lower edge of the blade
rib can be positioned substantially parallel to the base of the light fixture
and, in another aspect,
the upper edge of the blade rib can be positioned substantially parallel to
the base of the light
fixture. In yet another aspect, the lower edge of each blade rib can be
positioned substantially
parallel to the ceiling plane when the louver assembly is mounted to the light
fixture housing.
In this aspect, it is contemplated that the lower edge of each of the blade
ribs can be positioned
in a common plane that can be, in one example, substantially co-planar with
the ceiling plane.
[00036] In another aspect, a portion of the upper edge 28 of the blade rib can
define at least
one light source notch 30 that is configured to partially surround the light
source 14. As shown
in Figures 3 and 8A, in the exemplary embodiment with two elongated light
sources, the upper
edge 28 of each blade rib will define two light source notches 30 that are
spaced to partially
surround the substantially parallel light sources. In another aspect, the
upper edge 28 of each
blade rib of this embodiment can have a center notch 32 positioned
intermediate the two
respective light source notches 30.
[00037] In a further aspect, the plurality of stringers 40 comprises a pair of
side stringers 42
and a center stringer 44. In one aspect, each side stringer 42 has a
substantially planar shape.
In another aspect, the center stringer 44 has a substantially V-shape in cross
section with two
tapered sides 46 that extend downwardly to a common apex edge 48. In one
aspect, when the
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louver assembly is connected to the light housing, the open end of the center
stringer is
configured to overlie a ballast cover 7 of the light housing 2, which is
typically longitudinally
disposed in the center of the base of the light housing. Optionally, the
tapered sides of the
center stringer can generally match the angle of the respective sides of the
ballast cover.
[00038] In a further aspect, the center stringer 44 defines a plurality of
apex slots 50 that
extend upwardly on each tapered side 46 from the apex 48. In one aspect, each
apex slot 50 is
oriented substantially transverse to the longitudinal axis of the center
stringer.
[00039] In one exemplary aspect shown in Figure 4, the louver assembly 10 is
formed by
assembling the respective side stringers 42 and the center stringer 44 that
extend in the
longitudinal direction of the light fixture, with two end blade ribs 22 and
five center blade ribs
24 that extend in the transverse direction. The two end blade ribs 22 form the
respective end
faces of the louver assembly and extend the substantial width of the interior
cavity of the door
frame 12. The respective side stringers 42 form the longitudinal edge faces of
the louver
assembly and, along with the center stringer 44, extend the substantial length
of the interior
cavity of the door frame. In one aspect, it is contemplated that both the
stringers 40 and the
blade ribs 20 extend upwardly to a depth that, when mounted therein the light
fixture, the upper
edge 28 of the blade ribs 20 and the top edge 45 of the stringer members 40
extend above a
plane that extends substantially parallel to the ceiling plane and that
bisects a bottom portion of
the at least on light source 4.
[00040] Of course, it is contemplated that various size louver assemblies 10
may be used
constructed to fit light fixture housings 2 of differing size by varying the
number of
longitudinal stringers and transverse blade ribs that comprise the louver
assembly, along with
their dimensions. In this fashion, it is contemplated that the louvers can be
formed in an array
of cells as desired. For example, the exemplified louvers illustrated in the
present application
are for a 14 cell louver in a 7 cell X 2 cell array. It is contemplated that
the array of cells for
the louver can be selected as desired, such as, for example and not meant to
be limiting, a 12
cell louver in a 6 cell X 2 cell array.
[00041] In one exemplary aspect, the blade ribs are mounted therein a channel
defined in
support members of the door frame 12 and the respective stringers are mounted
and fixed to
the respective blade ribs. In a further aspect, tabs can be used to secure the
blade ribs 20 and
the respective stringers 40 to each other. In one exemplary aspect, at least
one end tab 60 can
extend outwardly from each of the respected ends of the blade rib 20. These
end tabs are
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Utility Patent Application
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inserted into slots 62 defined thereon the two opposing side stringers.
Further, at least one
outwardly extending tab 64 can be defined on upper portions of the central
notch of the blade
rib that are configured to be received within slots 66 defined above the apex
slot of the center
stringer. Further, it is contemplated that at least a portion of the blade rib
can be inserted into
the apex slot of the center stringers. The respective tabs 60, 64 are bent or
folded-over such
that the respective stringers and blades are substantially fixed in relation
to each other.
[00042] In one aspect, when the stringers and blade ribs are positioned, the
respective side
surfaces of the stringers are oriented at an acute angle relative to the plane
of the door frame.
Thus, the respective surfaces of the stringers face downwardly to reflect
incident light emitted
by the respective light sources downwardly into the room. Further, the
reflective surfaces, i.e.,
the front and back reflective faces of the connected blade ribs 20, are
positioned substantially
upright and generally transverse to the ceiling plane.
[00043] Thus, in the illustrated embodiment, the outer periphery of the louver
assembly is
substantially defined by the two side stringers 42, which extend in the
longitudinal direction,
and the two end blade ribs 32, which extend in the transverse direction.
Referring to Figures
9-11J, in one aspect, at least a portion of the lower edge 26 of each blade
rib comprises a rolled
edge. In another aspect, as shown in Figures 12A-12J, at least a portion of
the upper edge 28
of each blade rib comprises a rolled edge. In a further aspect, at least a
portion of the top edge
43 of each stringer comprises a rolled edge. It will be appreciated that
forming a rolled edge
on the respective lower or upper edge 26, 28 of each blade rib and/or the top
edge 45 of each
stringer increases their structural rigidity, which reduces deflection and
bowing of the
respective blade ribs 20 and stringers 40. Alternative embodiments of the
rolled lower edge 26
of the blade rib are shown in Figures 11A-11J and alternative embodiments of
the rolled upper
edge 28 of the blade rib are shown in Figures 12A-12J.
[00044] In another aspect, when the stringers and blade ribs are connected
together, the
bottom edge of at least one stringer member of the plurality of stringer
member is recessed
above the lower edges of the plurality of blade ribs. A notch 49 can be
defined in a portion of
the rolled lower edge 26 of the blade rib that is configured to cooperate with
the common apex
edge of the center stringer. In this aspect, the common apex edge and the
lower edges of the
plurality of blade ribs can be positioned in or proximate to a substantially
common plane.
[00045] In one aspect, the rolled lower edge 26 of the blade rib provides for
damage
resistance and increased strength that allows for general planar construction
with increased
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optical efficiency over conventional V formed cross blades. The flat,
substantially upright,
blade ribs 20 of the present invention increases optical efficiency of the
light fixture because
the subtended angle is reduced over the conventional V-shaped or parabolic-
shaped cross blade
louver designs. In another aspect, the rolled lower edge 26 of the blade rib
20 provides a visual
thickness that enhances the louver assembly's integrity and quality.
[00046] In a further aspect, the light source notches 30 formed in the upper
edge of the
blade rib allows for the use of a taller blade rib which yields a deeper
louver appearance as
well as providing superior off-axis shielding. In yet another aspect, the
light source notches 30
also allow the light source(s), such as the exemplified elongate lamps, to be
positioned lower in
the light fixture than would be otherwise possible. Having the lamp(s)
positioned lower in the
fixture, i.e., closer to the opening of the fixture and the ceiling plane,
acts to enhance the
overall light fixture efficiency.
[00047] In a further aspect of the invention, referring to Figures 1-9, each
blade rib 20 can
be at least partially corrugated. In another aspect, each stringer 40 can be
at least partially
corrugated. In various exemplary aspects, it is contemplated that a select one
or all off the
respective blade ribs and stringers of the louver assembly can be corrugated.
In one aspect,
corrugation of the blade ribs 20 and/or stringers 40 provides material
strength and resistance to
bending. As one skilled in the art will appreciate, this allows for the use of
thinner materials
than would normally be required. Further, the corrugation of the blade ribs
and/or stringers
provides material variation yielding an upscale appearance and luminance
gradient changes in
parallel bright and dark bands to lower perceived brightness. Additionally,
the corrugation
pattern reduces specular reflections and yields a smooth uniform blade
appearance. The
pattern also serves to disguise any blade rib and/or stringer imperfections.
In a further aspect,
the portion of the blade ribs proximate the rolled edge is not corrugated so
that the forming
consistency of the rolled edge embodiment is increased.
[00048] In addition, one skilled in the art understands that if a single light
source4 is
utilized, the louver assembly 10 would comprise the pair of side stringers 42
and the plurality
of blade ribs 20 as the center stringer 44 is not necessary in this
embodiment. Further, the
blade rib would only need to define a single light source notch in the upper
edge of the blade
rib as the central notch 32 is not required.
[00049] The stringers and blade ribs which comprise louver assembly 10 are
preferably
made from a lightweight, thin metal or ultra-thin material, such as aluminum
or steel. In one
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01182.0049U2
aspect, it is preferred to use steel to form the respective blade ribs and/or
stringers of the louver
assembly to both provide strength and damage resistance. Further, the use of
steel materials
allows for the manufacture of substantially planar blade ribs with their
optical efficiency
advantages. In another aspect, the use of steel materials yields economic
advantages over the
use of more traditional aluminum.
[00050] In another aspect, the design of the louver assembly of the present
invention
promotes the use of powder paint finishing yielding high reflectivity, field
cleanability and/or
dirt resistance. The design also allows for the use of paint after assembly
finishing processes
with its attendant economic advantages in the market verses requiring painting
before
assembly.
[00051] It is contemplated that the louver assembly of the present invention
can be sized
and shaped to fit into existing high volume fixture and door frame components.
As noted
above, the louver assembly also provides economic advantages in regard to
material content,
shipping and storage efficiencies, and installation and performance
enhancements to the end
user.
[00052] Although several embodiments of the invention have been disclosed in
the
foregoing specification, it is understood by those skilled in the art that
many modifications and
other embodiments of the invention will come to mind to which the invention
pertains, having
the benefit of the teaching presented in the foregoing description and
associated drawings. It is
therefore understood that the invention is not limited to the specific
embodiments disclosed
herein, and that many modifications and other embodiments of the invention are
intended to be
included within the scope of the invention. Moreover, although specific terms
are employed
herein, they are used only in a generic and descriptive sense, and not for the
purposes of
limiting the described invention.
11
