Abstrict A lighting device (32) is provided to illuminate indicia (18) of
an EXIT sign (10) having a sign housing (12) defining an enclosure
(22) therein and having a primary electrical power source. The lighting
device is provided with a reflector (40) having a shallow V-shaped
contour (434445) defining a centrally located valley in the reflector
and a source of illumination (42) positioned in the valley of the
reflector and powered by the primary power source, the source of
illumination including two rows of LEDs (65), each row having a
plurality of LEDs, and the rows being separated from one another
and positioned on either side of the valley. The LEDs are positioned
on either side of the valley (4445) a sufficient distance from
the valley to illuminate the edges of the sign parallel to the valley
while preventing areas within the valley from having dark and/or
unilluminated spots. The rows of LEDs are mounted on opposite edges
of a printed circuit board (70) positioned in the valley of the
reflector. A side of the printed circuit (72) board facing the indicia
to be illuminated is coated with a reflective material. A modular
power supply (36) is provided for attachment to a rear side of the
reflector (87) above or below a center line (88) perpendicular to
the valley. The modular power supply (36) provides a primary source
of power (97), and may also include an emergency electrical power
supply (107).
Claims What is claimed is:
1. A lighting device for illuminating indicia of an EXIT sign having
a sign housing defining an enclosure therein and having indicia
to be illuminated and having a primary electrical power source,
comprising:
a reflector having a shallow V-shaped contour defining a centrally
located valley therein;
said reflector including a first reflective surface on a first
side of said valley and a second reflective surface on a second
side of said valley; and
illumination means positioned in said valley of said reflector
to be powered by the primary electrical power source, said illumination
means including two rows of light emitting diodes, each row having
a plurality of light emitting diodes, said rows being separated
from one another and positioned on either side of said valley for
illuminating said reflector V-shaped contour including said valley.
2. A lighting device according to claim 1 wherein said V-shaped
contour is vertically oriented in said reflector, and wherein said
rows of light emitting diodes are positioned on either side of said
V-shaped contour.
3. A lighting device according to claim 2 wherein said rows of
light emitting diodes are positioned a sufficient distance from
said V-shaped contour to provide illumination to the sides of the
EXIT sign housing parallel to said V-shaped contour.
4. A lighting device according to claim 1 wherein each of said
light emitting diodes are positioned adjacent to said reflector
and at a distance from the indicia to be illuminated.
5. A lighting device according to claim 1 further comprising baffle
means mounted to said reflector for minimizing the area within said
reflector required to be illuminated by said rows of light emitting
diodes.
6. A lighting device according to claim 1 wherein said rows of
light emitting diodes are mounted on opposite edges of a printed
circuit board, said printed circuit board being mounted in said
V-shaped contour.
7. A lighting device according to claim 6 wherein said printed
circuit board is part of said illumination means.
8. A lighting device according to claim 6 wherein a side of said
printed circuit board facing the indicia to be illuminated is coated
with a reflective material.
9. A lighting device according to claim 8 wherein said reflective
material is at least one layer of white solder mask.
10. A lighting device according to claim 6 wherein said printed
circuit board has electrical components thereon for said illumination
means.
11. A lighting device according to claim 1 further comprising
a power supply module for providing the primary electrical power
source to said illumination means, said power supply module being
attached to a rear surface of said reflector either above or below
a horizontal center line of said reflector.
12. A lighting device according to claim 11 wherein said power
supply module includes rectifier means for rectifying the primary
electrical power source into direct current for powering said illumination
means.
13. A lighting device according to claim 11 wherein said power
supply module further includes an emergency electrical power source
to provide auxiliary power to said illumination means in the event
of failure of the primary electrical power source.
14. A lighting device according to claim 13 wherein said emergency
electrical power source includes at least one rechargeable battery,
a charging device for keeping said at least one rechargeable battery
fully charged during periods of non-use and transfer means for switching
between said emergency electrical power source and the primary electrical
power source.
15. A lighting device according to claim 1 further comprising
a diffuser deflector placed in front of said illumination means
between said illumination means and the indicia to be illuminated.
16. A lighting device according to claim 15 wherein said diffuser
deflector is opaque.
17. A lighting device according to claim 15 wherein said diffuser
deflector is transparent.
18. A lighting device according to claim 2 wherein at least one
row of said light emitting diodes is parallel to said V-shaped contour.
19. A lighting device according to claim 2 wherein one row of
said light emitting diodes is parallel to said V-shaped contour,
and another row of said light emitting diodes is staggered to generally
follow the contour of one-half of an X in the word EXIT.
20. A lighting device according to claim 19 wherein said rows
of light emitting diodes are positioned a sufficient distance from
said V-shaped contour to provide illumination to the sides of the
EXIT sign housing parallel to said V-shaped contour.
21. A lighting device according to claim 2 wherein each of said
light emitting diodes are positioned adjacent to said reflector
and at a distance from the indicia to be illuminated.
22. A lighting device according to claim 2 further comprising
baffle means mounted to said reflector for minimizing the area within
said reflector required to be illuminated by said rows of light
emitting diodes.
23. A lighting device for illuminating indicia of an EXIT sign
having a sign housing defining an enclosure therein and having indicia
to be illuminated and having a primary electrical power source,
comprising;
a reflector having a shallow V-shaped contour defining a centrally
located valley therein; said reflector including a first reflective
surface on a first side of said valley and a second reflective surface
on a second side of said valley;
illumination/means positioned in said valley of said reflector
to be powered by the primary electrical power source, said illumination
means including two rows of light emitting diodes, each row having
a plurality of light emitting diodes, said rows being separated
from one another and positioned on either side of said valley for
illuminating said reflector V-shaped contour including said valley;
and
a power supply module for providing the primary electrical power
source to said illumination means, said power supply module being
attached to a rear surface of said reflector.
24. A lighting device according to claim 23 wherein said power
supply module is attached either above or below a horizontal center
line of said reflector.
25. A lighting device according to claim 23 wherein said power
supply module covers the entire rear surface of said reflector.
26. A lighting device according to claim 23 wherein said power
supply module includes rectifier means for rectifying the primary
electrical power source into direct current for powering said illumination
means.
27. A lighting device according to claim 23 wherein said power
supply module further includes an emergency electrical power source
to provide auxiliary power to said illumination means in the event
of failure of the primary electrical power source.
Description BACKGROUND OF THE INVENTION
The present invention relates generally to electrical lighting
sources and, more particularly, to electrical lighting sources in
illuminated EXIT signs.
Under current local fire and building codes, buildings to which
the public have access are required to have signage therein identifying
the exits. Most of these signs are required to exhibit a specific
amount of illumination and, often times, must have an emergency
backup power source to provide emergency power to the light for
a specific period of time during periods when utility power to the
building is discontinued, thereby illuminating the light to facilitate
egress of persons from the building.
Traditionally, two 15-watt incandescent lamps driven by 120 volt
alternating current (120 VAC) have been employed to provide normal
illumination while two 3.6-watt incandescent lamps driven by a self
contained emergency battery power supply are used for illumination
during power failure situations. A switching or transfer device
will automatically operate the emergency backup illumination system
when a power failure is detected.
While these traditional EXIT sign lighting arrangements perform
adequately, they do have a few drawbacks. A major drawback is that
the incandescent bulbs use large amounts of electric power thus
requiring high operating costs and a relatively large emergency
battery power supply for use during emergency lighting situations.
Furthermore, while the incandescent bulbs provide adequate illumination,
such bulbs do not have a long life in service and require frequent
replacement.
To alleviate the drawbacks associated with incandescent bulbs,
many manufacturers are beginning to utilize light emitting diodes
(LEDs) rather than incandescent bulbs in EXIT signs. Each LED provides
a relatively small amount of light as compared to traditional incandescent
bulbs whereby a large number of LEDs must be used to provide the
same amount of illumination offered by the traditional incandescent
bulbs.
It is an object of the present invention to provide a novel lighting
device for an EXIT sign using a plurality of LEDs.
It is also an object to provide such a lighting device which allows
the LEDs to be powered by both a normal utility electrical power
supply (120 VAC) and, during emergency power situations, an emergency
battery power supply and associated charging and transfer circuitry.
Still another object is to provide such a lighting device in which
the LEDs are arranged in the EXIT sign to provide the amount of
illumination required by building codes.
A further object is to provide such a lighting device which may
be readily and economically fabricated and would enjoy a long life
in operation.
A still further object of the present invention is to provide such
a lighting device which may be easily retrofit into the housing
of an existing EXIT sign utilizing incandescent bulbs.
Another object is to provide such a lighting device which may be
arranged back to back with other such lighting devices to provide
a source of light on two sides, such devices being retrofit into
an existing housing of an EXIT sign.
SUMMARY OF THE INVENTION
According to the present invention, a lighting device is provided
to illuminate indicia of an EXIT sign having a sign housing defining
an enclosure therein and having a primary electrical power source.
The lighting device is provided with a reflector having a shallow
V-shaped contour defining a centrally located valley in the reflector
and a source of illumination positioned in the valley of the reflector
and powered by the primary power source, the source of illumination
including two rows of LEDs, each row having a plurality of LEDs,
and the rows being separated from one another and positioned on
either side of the valley.
In further accord with the present invention, the V-shaped contour
is vertically oriented in the enclosure, and the rows of LEDs are
positioned on either side of the V-shaped contour, the LEDs being
positioned adjacent to the reflector to maximize the distance between
the LEDs and the indicia to be illuminated. The LEDs are also positioned
on either side of the valley a sufficient distance from the valley
to illuminate the edges of the sign parallel to the valley while
preventing areas within the valley from having dark and/or unilluminated
spots. The rows of LEDs are mounted on either side of a printed
circuit board positioned in the valley of the reflector. A side
of the printed circuit board facing the indicia to be illuminated
may be coated with a reflective material to further enhance the
distribution of light within the housing. Alternatively, the printed
circuit board may be translucent or transparent to improve light
distribution and transmission within the housing. The printed circuit
board is electrically connected to, and has electrical components
for, the plurality of LEDs.
In still further accord with the present invention, internal baffles
may be positioned on the reflector at or near the edges of the reflector
parallel to the valley, the baffles also being positioned at the
edges of the indicia to be illuminated to minimize the area required
to be illuminated by the light sources. For special worded signs
and retrofit applications, the internal baffles may be repositioned
or omitted completely.
According further to the present invention, a modular power supply
is provided for attachment to a rear side of the reflector, the
modular power supply being positioned above or below a center line
perpendicular to the valley. The modular power supply includes rectifier
means attached to a utility power source for rectifying the source
of power prior to being provided to the LEDs. Desirably, the modular
power supply also includes an emergency electrical power supply
to provide auxiliary power to the LEDs in the event of failure of
the primary electrical power supply. The emergency electrical power
supply is at least one rechargeable battery and includes a charging
device for keeping the at least one rechargeable battery fully charged
during periods of nonuse. The emergency electrical power supply
is mounted within the modular power supply and is optionally connected
to the primary electrical power supply to detect failure of the
primary electrical power supply and thereafter provide auxiliary
power to the LEDs.
According still further to the present invention, a pair of modular
power supplies may be positioned between a pair of lighting devices
to provide illumination within a housing having indicia on two sides
of the housing. Alternatively, a single modular power supply mounted
between a pair of lighting devices may be provided for illuminating
a housing having indicia on two sides, the single modular power
supply covering the entire rear side of the lighting device reflector.
The foregoing and other objects, features and advantages of the
present invention will become more apparent in light of the following
detailed description of exemplary embodiments thereof, as illustrated
in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a lighting device of
the present invention in relation to an EXIT sign housing;
FIG. 2 is an exploded perspective view of an LED array having red
LEDs and a reflector of the lighting device of FIG. 1;
FIG. 3 is a cross-sectional view of the reflector and LED array
taken along line 3--3 of FIG. 2 and illustrating the height relationship
between the LED array and the reflector;
FIG. 4 is a top view of an alternative LED array having amber LEDs
for use with the lighting device of FIG. 1;
FIG. 5 is a top view of a second alternative LED array having green
LEDs for use with the lighting device of FIG. 1;
FIG. 6 is a top view of an alternative reflector for use with the
lighting device of FIG. 1 showing baffles located within the reflector;
FIG. 7 is an exploded perspective view of the reflector and power
supply module showing a power supply test circuit and bracket in
relation to the reflector;
FIG. 8 is an exploded perspective view of a power supply module
for use with the lighting device of FIG. 1;
FIG. 9 is a perspective view showing two lighting devices, each
lighting device having a power pack mounted on a rear surface of
the reflector for back-to-back arrangement of the lighting devices;
FIG. 10 is a top view showing two lighting devices having power
supply modules located there between;
FIG. 11 is a perspective view showing a power supply module which
covers the entire rear surface of a reflector;
FIG. 12 is an exploded perspective view of an alternative housing
for use with the lighting device of the present invention;
FIG. 13 is a perspective view, partially broken away, of the lighting
device of FIG. 1 having a baffle placed in front of the LED array;
and
FIG. 14 is a cross-sectional view taken along line 14--14 of FIG.
13.
DETAILED DESCRIPTION OF THE INVENTION
The lighting device of the present invention is particularly well
suited for retrofit mounting within a housing of an existing EXIT
sign. A power supply module may be provided for use with the lighting
device to provide both a direct or primary source of power and an
emergency backup source of power. The lighting device of the invention
may be provided as a single unit within an EXIT sign housing having
indicia to be illuminated on one side, or a pair of lighting devices
of the present invention may be provided arranged back-to-back for
illuminating two sides of an EXIT sign housing.
Referring to FIG. 1 an EXIT sign 10 is mountable both on a canopy
bracket (not shown) and a standard electrical junction box (not
shown) in a manner explained in co-pending U.S. patent application
Ser. No. 07/925133 entitled CANOPY MOUNTING DEVICE FOR EXIT SIGNS
AND THE LIKE. With this arrangement, the EXIT sign construction
of this invention can be mounted directly to a standard electrical
junction box found in a ceiling or wall of a building in any desired
location.
The EXIT sign 10 comprises a central rectangular shaped frame 12
with front and back cover members 14 16 at least one of which
incorporates a large stencil 18 having the letters "EXIT"
in the major surface thereof and a colored diffuser 20 therebehind.
The diffuser may be made of a transparent material which is colored
or screened to a desired color. Although the invention is described
herein as being used with a sign having the letters "EXIT"
in a large stencil, it will be understood by those skilled in the
art that the principles of the invention disclosed herein are also
applicable to signs having other letters in a stencil.
The central rectangular shaped frame 12 and the front and back
cover members 14 16 are snapped-fit together and cooperate to form
a housing 10 having an enclosure 22 containing the necessary internal
electrical lighting components. The front and back covers 14 16
can use a plurality of finger clips (not shown) to hold them in
assembly with the central rectangular shaped frame 12. The EXIT
sign 10 is preferably molded from a plastic resin such as an engineering
type thermoplastic, e.g., ABS, polycarbonate or polystyrene oxide,
but it should be apparent to those skilled in the art that it may
be manufactured from other suitable materials.
Within the enclosure 22 of the EXIT sign 10 a wiring compartment
24 is formed by a retaining wall 28 which extends around the interior
sides and top of the central rectangular shaped frame 12. The retaining
wall 28 is mounted on its ends to a bottom side 29 of the rectangular
shaped frame 12. In a manner explained further hereinafter, the
wiring compartment 24 contains an appropriate wiring harness 30
or other suitable signal transmission media for providing utility
power to a primary power source for the lighting device of the present
invention.
An emergency power supply test and indication device 31 which
is described in greater detail hereinafter, may be provided for
mounting in an aperture 33 formed in the bottom side 29 of the rectangular
shaped frame 12. The indication device 31 is provided with tabs
34 for interlocking and sliding engagement with corresponding channels
35 formed in the bottom side 29 of the rectangular shaped frame
12 on opposite sides of the aperture 33.
The lighting device 32 of the present invention is intended for
either retrofit application in the enclosure 22 of an existing EXIT
sign 10 and also for application in a new EXIT sign. The lighting
device 32 is positioned within the enclosure 22 behind the diffuser
20 so that light provided by the lighting device 32 may be projected
through the diffuser and the front cover stencil 18 for lighting
the stencil letters. The lighting device 32 is provided with at
least one power supply module 36 the power supply module 36 being
configured for attachment on a rear side of the lighting device
32 above or below a horizontal center line. As will be described
in greater detail hereinafter, the power supply module 36 is used
to provide a primary power source to a light array of the lighting
device 32 and also may comprise a backup power supply and additional
circuitry as desired for providing enhanced features with the EXIT
sign 10.
Referring now to FIGS. 1 2 and 3 the lighting device 32 comprises
a reflector 40 and a light array 42. The reflector 40 is generally
concave or V-shaped having a central vertically oriented valley
43 with reflective surfaces 4445 extending outwardly therefrom.
The concave or V-shaped design of the reflector is shown in greater
detail in FIG. 3. A pair of snap-fit tabs 47 47' are provided on
a bottom side of the reflector 40 and a pair of mounting tabs 49
49' are provided on the top side of the reflector 40. The mounting
tabs 49 49' have tab ends 50 50' and apertures 52 52' formed
therein so that the mounting tabs 49 may either provide snap-fit
mounting or mounting using other fastening means such as threaded
fasteners (not shown). The mounting tabs 49 49' and snap fit tabs
47 47' cooperate to hold the lighting device to either one of the
EXIT sign cover members 14 16 having the stencil 18.
The lighting array 42 is mounted in the valley 43 of the reflector
32 by means of threaded fasteners 56 which are received through
apertures 60 in the array and are fastened to internally threaded
posts 62 located in the valley 43 of the reflector 32. The lighting
array 42 comprises two rows of LEDs 65 each row being positioned
on either side of the valley 43. As shown in FIG. 3 once the array
42 is mounted in the valley 43 the rows of LEDs 65 are positioned
immediately adjacent to the reflector surfaces 4445.
It has been found that for optimal illumination of the stencil
18 the rows of LEDs 65 should be positioned as far away from the
diffuser 20 and stencil 18 as possible within the reflector valley
43 and also, the LEDs 65 should be offset from the reflector center-line
or valley 43 a sufficient amount so that the light from the LEDs
65 reaches the edges of the reflector 40 to illuminate the entire
stencil 18. It has also been found that depending on the power output,
e.g., the amount of illumination, provided by the LEDs 65 used in
the lighting array 42 various array configurations may be required.
For example, the array 42 illustrated in FIG. 2 comprises twelve
LEDs 65 making up two rows with six LEDs 65 in each row. The two
rows are evenly spaced apart on either side of the valley 43. This
configuration is particularly useful for higher intensity LED light
sources such as red LEDs. The LEDs 65 are mounted on a circuit board
70 and provided power from the power supply module 36 as described
hereinafter. A side of the circuit board 72 facing the diffuser
20 and stencil 18 may be coated with a reflective material, such
as a white solder mask, to further enhance the reflection of light
within the reflector 40 and through the diffuser 20 and stencil
18.
For lower intensity LEDs, such as green LEDs, a different array
configuration and/or additional LEDs may be required to provide
a sufficient amount of illumination for the stencil 18. Additionally,
various array configurations may be used to improve the overall
visual appearance of the stencil. Referring now to FIG. 4 an example
of an array 42 using amber LEDs 65 is shown. In this case, the array
comprises twelve LEDs 65 making up two rows of six LEDs 65 each.
However, the rows are further offset from each other than the rows
of red LEDs (FIG. 2), and additionally, one row of LEDs is staggered
to provide the proper illumination within the reflector. Although
amber LEDs typically do not have the same intensity level as the
red LEDs, there is sufficient intensity provided by twelve amber
LEDs to provide the required amount of illumination through the
stencil 18 provided that the rows of LEDs are offset from one another
and one row of LEDs is staggered. As is seen in FIG. 4 one row
of LEDs generally follows the outline of the letter I in the word
EXIT, and the other row of LEDs generally follows the outline of
one-half of the letter X in the word EXIT. Using this arrangement,
in conjunction with a reflective surface 72 provided on the circuit
board 70 provides a sufficient amount of illumination to illuminate
the letters in a stencil containing the-word EXIT.
Referring now to FIG. 5 a second alternative LED array 42 is illustrated.
In the FIG. 5 embodiment, twenty-four LEDs 65 are provided in two
rows of twelve LEDs 65. As with the FIG. 4 embodiment, the rows
of LEDs are further offset from each other than the rows of higher
intensity red LEDs, and one row of LEDs is staggered to generally
follow the outline of the letter X in the word EXIT. This arrangement
is useful for a low intensity light source such as a green LED.
It has been found that this arrangement provides sufficient illumination
through the letters of the word EXIT in a stencil 18.
Referring now to FIGS. 2 and 6 in conjunction with the LED arrays
illustrated in FIGS. 4 and 5 baffles 80 are positioned within the
reflector 40 to limit the area within the reflector 40 required
to be illuminated by the LED array 42 when lower intensity LEDs
are used. However, these baffles 80 may also be used with the higher
intensity LEDs if desired. Referring also to FIG. 1 Chevrons 82
may be provided on either side of the word EXIT in the stencil 18
and therefore, the baffles 80 are arranged so that light from the
array 42 may reach the Chevrons 82. Additionally, cut outs 85 are
provided in either end of the reflector 40 in the location of the
tip of Chevrons 82 so that light may reach the tip of the Chevrons
82.
It will therefore be understood by those skilled in the art that
when an array 42 is placed in the valley 43 of the reflector 32
and the array 42 is energized, light from the rows of LEDs 65 in
the army 42 will project onto the reflecting surfaces 4445 and
be directed outwardly through the diffuser 20 and stencil 18. If
lower intensity bulbs are used, then either the arrangement of FIG.
4 or FIG. 5 may be used to ensure that sufficient light is provided
throughout the whole reflector area. Additionally, baffles 80 may
be provided within the reflector 40 when lower intensity light arrays
42 are used to minimize the area required to be illuminated by the
LED array. In either case, the baffles 80 are arranged such that
the light may reach a Chevron 82 placed on either or both sides
of the word EXIT, and the ends of the reflector 40 in the area of
the Chevron 82 have cut outs 85 such that light may reach the tip
of each Chevron 82. Each of the circuit boards 70 which carry the
rows of LEDs 65 may be coated with a reflective material on a side
72 facing the diffuser 20 and stencil 18 such that light reflected
within the reflector 40 will reflect off the side 72 of the circuit
board and be reflected out through the stencil 18. This will prevent
the formation of local areas of low intensity light which would
show up as dim or unlit spots on the EXIT sign.
Depending on the color of LEDs used in the array 42 various diffusers
20 may be used to provide the proper coloration of the letters in
the stencil 18. For example, if red LEDs are used, then a clear
polycarbonate diffuser panel with a red day glow coloration silk
screened on one side may be provided. Alternatively, other materials
may be utilized for the diffuser 20. For example, if either green
or amber LEDs are used, a sheet of milk white translucent styrene
may be used as the diffuser 20. In the case of green LEDs, the sheet
of styrene may be coated on one side with a day glow green coloration.
Referring now to FIG. 7 a power supply module 36 may be mounted
on a rear side 87 of the reflector 40 above or below a horizontal
center line 88 of the reflector 40 which is perpendicular to the
reflector valley 43 (FIG. 2). Resiliently deformable retaining members
90 are attached on sides of the power supply module 36 for mating
engagement with apertures 95 formed in the reflector 40. Four apertures
95 may be provided in the rear side 87 of the reflector 40 so that
the power supply module 36 may be either mounted above or below
the horizontal center line 88 of the reflector 40.
Referring also to FIG. 8 the power supply module is provided with
electronic circuitry 97 which is mounted on a circuit board 98 and
positioned within the power supply module 36 for providing a primary
power source to the array. The electronic circuitry 97 may be provided
with utility power from a utility 120 volt AC power supply via the
wiring harness 30 (FIG. 1) from electrical leads (not shown) which
extend into an electrical junction box (not shown) found in the
ceiling or wall of a building. The electronic circuitry 97 comprises
means for rectifying the 120 volt AC power into a DC power supply
in a way which is well known in the art. The DC power may be used
to power the LEDs in the array. The DC power is provided on a line
100 which may terminate in a connector 102 the line 100 and connector
102 may be passed through an aperture 105 formed in the rear surface
87 of the reflector, and the connector 102 may be attached to a
terminal (not shown) on the circuit board 70 (FIG. 2) of the array
for powering the LEDs 65 (FIG. 2) in the array 42 (FIG. 2).
The power supply module 36 may also be provided with an emergency
backup power source 107 e.g., at least one battery, to provide
power to light the LEDs in case the primary power source is not
available. In this case, the circuitry 97 is also be provided with
transfer circuitry for automatically powering the LED array from
the emergency power supply 107 in the event that the primary power
source is not available. Additionally, the circuitry 97 may be provided
with battery charging circuitry to maintain the charge on the battery
107 when it is not in use. The transfer circuitry and battery charging
circuitry may be of a type know in the art. Alternatively, an example
of transfer circuitry and battery charging circuitry of the type
which may be used with the present invention is given in commonly
owned, co-pending U.S. patent application Ser. No. 08/160583 entitled
LIGHTING DEVICE USED IN AN EXIT SIGN.
Referring to FIG. 8 the power supply module 36 is provided in
two pieces including a housing 112 and a removable cover 114 which
is mounted to the housing 112 with threaded fasteners 115. The threaded
fasteners 115 are received through apertures 118 formed in the removable
cover 114 and are engaged with internally threaded mounting posts
120 molded with the housing 112. As with the EXIT sign 10 the power
supply module 36 is preferably molded from a plastic resin such
as an engineering type thermoplastic, e.g., ABS, polycarbonate or
polystyrene oxide, but it should be apparent to those skilled in
the art that it may be manufactured from other suitable materials.
Referring again to FIG. 7 an emergency power supply test and indication
device 31 of a type known in the art may be mounted on tabs 130
attached to the bottom of the reflector 40. The indicator 31 includes
a printed circuit board 133 having test circuitry mounted thereon
which is surrounded by a piece of insulating material 136 and attached
to the tabs 130 via a mounting bracket 138 using threaded fasteners
140. A wiring harness 142 having a connector 144 for engagement
with a terminal (not shown) on the circuit board 133 may be provided
to connect the modular power supply circuitry 97 to the test assembly
31.
Referring now to FIGS. 9 and 10 a pair of lighting devices 32a,
32b are shown, each having a power supply module, 36a and 36b mounted
above and below the horizontal center line 88 (FIG. 7), respectively.
The lighting devices 32a, 32b and power supply modules 36a, 36b
may be arranged back-to-back, as shown, to provide a two sided lighting
source for an EXIT sign 10 which has two sides. Alternatively, a
single lighting device 32a and power supply module 36a may be provided
as a single unit in a one sided EXIT sign as previously described
herein. Alternatively, referring to FIG. 11 when it is intended
that two lighting devices be arranged back-to-back as illustrated
in FIG. 10 a single power supply module 150 may be provided which
covers the entire rear surface of one of the lighting devices for
providing primary and emergency power to two lighting devices. Alternatively,
the single power supply module 150 may be provided with one lighting
device when additional test and monitoring equipment is provided
with the EXIT sign.
Although the invention was described herein for retrofit application
in an EXIT sign 10 molded from a thermoplastic, the invention is
also applicable to an EXIT sign having a die cast housing and a
die cast front panel as is known in the art. For example, referring
to FIG. 12 an EXIT sign having a die cast housing 157 and a die
cast front cover 159 is shown. The front cover has the letters "EXIT"
cut out in the major surface 160 thereof, and a stencil panel 163
is provided having the letters "EXIT" therein to provide
a more refined appearance. As with the thermoplastic housing, a
lighting device 32 and at least one power supply module 36 are positioned
within the housing 157 behind a diffuser 20 the lighting device
32 illuminating the letters in the stencil panel 163 through the
diffuser.
Although the invention has been illustrated with the light array
42 positioned between the reflector 40 and the diffuser 20 the
array being positioned immediately adjacent to the reflection panel,
a diffuser deflector 170 may be provided between the light array
42 and diffuser 20 if desired, as shown in FIGS. 13 and 14. Referring
to FIGS. 13 and 14 the diffuser deflector 170 may be particularly
useful with an array having high intensity LEDs to prevent hot spots
(bright spots) in local areas of a stencil corresponding to the
location of LEDs behind the stencil. The diffuser deflector 170
may be made of either an opaque or translucent material.
The invention has been described herein using either 12 or 24 LEDs
in an LED array 42. However, it will be understood by those skilled
in the art that various combinations of LEDs may be used to provide
the desired lighting effect. Considerations used to determine the
proper number of LEDs to use in an array include: the size of the
area to be illuminated; the light intensity produced by the LEDs;
the light beam pattern of the LEDs; the size of the stencil opening;
the specific diffuser material used; etc.
Although the invention has been described and illustrated with
respect to exemplary embodiments thereof, it should be understood
by those skilled in the art that the foregoing and various other
additions and omissions may be made therein and thereto without
departing from the spirit and scope of the present invention. |