Note: Descriptions are shown in the official language in which they were submitted.
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HOLO 0202 PCA
A NEW AND IMPROVED
INTERNALLY ILLUMINATED SIGN
Field Of The Invention
This invention relates generally to illuminat-
ed signs and more specifically to an illuminated sign
having internal illumination.
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Background Of The Invention
,
Internally illuminated signs have one or more
translucent faces or message areas which are illuminated
by lamps mounted inside the sign. While internally
illuminated signs are often preferred over externally
lighted signs, internally lighted signs of the prior art
have been much more expensive to construct than exter-
nally lighted signs, especially when the sign is large.Internally illuminated signs are usually lighted with
fluorescent lamps, although in some instances the light
in internally illuminated signs is provided by mercury
vapor or metal halide lamps. The translucent faces of
the sign can be either rigid or flexible. Small rigid
translucent faced internally illuminated signs often
have hinged faces in order to provide access to the
lamps for maintenance and relamping, whereas, large
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internally illuminated signs normally utilize flex faces
and are built up to thirty-six inches deep to allow a
person to enter the sign through the side and thereby
provide access to the lamps for maintenance and relamp-
ing. In order to provide a sign having sufficient depth
to allow human access, it i9 necessary for sign manufac-
turers to build a framework structure for the sign which
adds significantly to the cost of the sign. In exter-
nally lighted signs, aluminum extrusions which are
relatively inexpensive are often used as the outer
framing. However, since aluminum extrusions have a
practical cross-section limit of about fifteen inches,
the depth of the large internally illuminated signs
precludes sign manufacturers from using aluminum extru-
sions for the outside structure of the signs which
require human acces~, thereby greatly increasing con-
struction costs of internally illuminated signs of the
prior art. In addition, in internally illuminated signs
of the prior art, there has been difficulty in achieving
; 20 the desired uniformity of luminance acro~s the full area
of the sign face, since there is a tendency for the
portion of the face of the sign adjacent the lamp to be
much brighter than the rest of the sign face.
Brief Su~ary Of The In~rention
This invention relates to an internally
illuminated sign in which the need for human access into
the interior of the sign for maintenance and relamping
is eliminated thereby eliminating the need for a deep
sign and the higher costs associated with such sign
construction. The present invention provides an inter-
nally illuminated sign in which a luminaire mounted on
the border or periphery of the sign uniformly illumi-
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nates the faces of the sign. A significant feature of
the present invention is uniformly illuminating the face
or faces of the sign. AS noted above, in internally
illuminated signs of the prior art, there was a tendency
for the portions of the sign face adjacent the lamps to
be brighter than the rest of the sign face resulting in
an uneven and undesirable distribution of light across
the sign face.
The luminaire mounted on the border and
internally illuminating the faces of the internally
illuminated sign includes an aluminum reflector for
distributing light in a fan-shaped pattern laterally
along the sign and parallel to the sign faces, and a
refractor which intercepts the light and directs the
` 15 light to provide a uniform luminance on the sign faces
while at the same time blocking direct source light from
penetrating the sides of the refractor and producing a
. bright spot on a portion of the sign face adjacent the
luminaire.
These and other features and aspects of the
invention, as well as its various bene~its, will be made
more clear in the detailed description of the invention
which follows.
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~, Brief De~cription Of The Drawin~
FIGURE 1 is a sectional view showing the
interior of an internally illuminated sign constructed
in accordance with an embodiment of the present inven-
tion, in which a number of luminaires mounted on the
border of the sign uniformly illuminate the faces of the
sign;
FIGURE 2 is a frontal sectional view of the
interior of one of the luminaires mounted on the border
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of the sign as pictured in Figure 1, illustrating a
luminaire reflector and the fan-shaped lateral distribu-
tion of light reflecting therefrom;
FIGURE 3 is a side sectional view of the
interior of one of the luminaires mounted on the border
of the sign as pictured in Figure 1 and Figure 2,
illustrating the parabolic contoured bottom of the
luminaire reflector of Figure 2 directing light rays
straight up;
FIGURE 4 is a frontal sectional view of the
interior of one of the luminaires mounted on the border
of the sign as pictured in Figure 1, illustrating a
luminaire refractor which through the use of prisms
provides an even distribution of light onto the inside
surfaces of the sign faces;
FIGURE 5 is a side sectional view of the
interior of the luminaire as pictured in Figure 3,
. illustrating the action of horizontal reflecting prisms
located on the outside surfaces of the sides of the
luminaire refractor adjacent the face~ of the sign
blocking and reflecting most of the direct light that
would normally produce excessive luminance on the sign
: face;
FIGURE 6 is a top sectional view of the side
sectional view of the interior of the luminaire pictured
in Figure 5, illustrating the light pattern resulting
from the action of vertical biasing prisms located on
the inside surface of the sides of the refractor;
FIGURE 7 is a perspective view of an alterna-
tive embodiment of the interior of the luminairesmounted on the border of the sign as pictured in Figure
1, shown with the reflector having fluted sections
vertically disposed in the luminaire housing to redirect
light on the sign translucent faces;
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FIGURE 8 is a perspective and partially
fragmented view of an alternative embodiment of the
luminaires mounted on the border of the sign as pictured
in Figure 1, shown including layers of adjustable
translucent panels for obtaining the correct of light
blockage;
FIGURE 9 is a perspective view of an alterna-
tive embodiment of the luminaire~ mounted on the border
of the sign as pictured in Figure 1, shown including
vertically disposed and spatially separated perforated
metal plates for use in reducing the brightness on the
sign translucent faces on the luminaire; and
FIGURE 10 is a perspective view of an alterna-
cive embodiment of the luminaires mounted on the border
of the sign as pictured in Figure 1, shown including
vertically disposed and spatially separated louvers for
reducing "bright spots" on the sign translucent faces.
De~cription Of The Invention
Referring to Figure 1, there is shown in an
. 20 embodiment of the present invention a sectional view of
the interior of an internally illuminated sign generally
identified by the reference numeral 10 in which a number
~ of luminaires 12 mounted at a lower periphery or border
: 14 of the sign 10 are adapted to provide a light distri-
~: 25 bution pattern generally identified by the reference
numeral 16 to uniformly illuminate the faces 18 of the
sign 10. Each of the luminaires 12 is mounted in such
- ~ a manner that its lamp or light source 20 is positioned
` below the translucent faces 18 of the sign 10 and has an
: 30 easily openable housing 11 which extends down below the
- sign 10. The housing 11 may be opened in any number of
ways, for instance, it may be pivotally mounted about a
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HOLO 0202 PCA -6-
hinge 13 and secured in a closed position by a latch 15,
so that it may be opened to provide easy acceæs to the
interior of the luminaire for maintenance and relamping.
With the luminaires 12 mounted at the lower
border 14 of the sign 10 r the luminaires can be opened
for maintenance and relamping without the need for a
deep sign to provide human access. Since the present
invention eliminates the necessity of having a deep
sign, the translucent faces 18 of the sign 10 can be
spaced less than 15 inches apart from one another and
the outer structure of the sign can be made out of
aluminum extrusion or other relatively inexpensive
~onstruction. While Figure 1 illustrates the utiliza-
tion of a number of luminaires, it should be apparent
that the number of luminaires necessary is dependent on
the size of the sign. Also, while in the embodiment of
. the invention illustrated in Figure 1, the sign has two
translucent faces the same principles of the present
invention apply whether the sign has one or more trans-
lucent faces. Furthermore, while in the embodiment of
the invention illu~trated in the drawings, the luminaire
i9 positioned at the bottom of the sign it is equally
satisfactory to position the luminaires anywhere along
the border of the sign such as at the top or the sides
for instance.
Referring to Figure 2, there is shown a
frontal sectional view of the interior of one of the
luminaires 12 mounted on the border of the sign 10,
- having therein the lamp or light source 20, a reflector
-30 22, made of aluminum or the like, positioned below the
light source 20 and a refractor 24. As illustrated in
Figure 2, the reflector 22 is designed to reflect the
light from the light source 20 in a fan-shaped pattern,
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generally identified by the reference numeral 26,
laterally across a segment of the sign 10.
In Figure 3 there is shown a side sectional
view of the interior of the luminaire 12 of Figure 2,
illustrating the parabolic contoured bottom 28 of the
reflector 22 reflecting light rays from the light source
20 up through the top 30 of the refractor 24 in a light
distribution pattern generally identified by the refer-
ence numeral 32, parallel to the face 18 of the sign 10.
With reference to Figure 7, there is further
shown an additional embodiment of reflector 22 having
fluted sections 33 vertically disposed in housing 11 to
redirect light and reduce the brightness of "hot spots"
or "bright spots" on the sign translucent faces 18 near
luminaires 12.
Figure 4 is a frontal sectional view of the
interior of the luminaire 12 in Figure 2, illustrating
the manner in which the refractor 24, by means of prisms
as shown in Figure 4, directs light from the light
source 20 into a uniform pattern of light, generally
identified by the reference numeral 34, onto the inside
surfaces of the sign faces 18.
Referring now to Figure 5, there is shown
again the side sectional view of the interior of the
luminaire 12 as pictured in Figure 3, now illustrating
a light pattern, generally identified by the reference
numeral 36, formed by the action of horizontal reflect-
ing prisms 37, as shown in Figures 3 and 5 on the
outside surfaces of the sides 38 of the luminaire
refractor 24 adjacent the translucent faces 18 of the
sign 10 blocking and/or reflecting and redirecting most
of the direct light from the light source 20 and mini-
mizing light penetration through the sides 38 of the
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refractor 24 that would normally produce excessive
luminance on the sign translucent faces 18.
All or a portion of these reflecting prisms 37
may be coated to assist in blocking and redirecting the
light rays. Reflecting prisms 37 may be selectively
coated with ceramic paints or other known heat-tolerant
paints which can provide similar blocking performance.
In the preferred embodiment, as shown in Figures 3-5,
prisms 37 are selectively rear surface metalized via
spraying or other known deposition techniques to obtain
the required light blocking and/or light redirection.
The coating process is applied to prisms 37 at a
selected angle depending on the prismatic structure in
order to partially coat the prisms. The uncoated areas
of the prismatic structure allow light to penetrate and
be refracted. The coated parts of the prismatic struc-
ture allow light to be redirected back to the reflector
I 22, allow light to be directed toward some other useful
part of the luminaire 12 or allow light to be blocked.
, 20 In an alternative embodiment as shown in
Figure 8, layers of translucent material 39 such as
white diffusing panels, for example, may be used to
` block light near the luminaire 12, thereby reducing the
brightness of the sign. Layering the translucent
material provides a means of adjusting the correct
amount of light blockage. Those skilled in the art will
thus recognize that multiple layers will block more
light, where necessary.
In yet another alternative embodiment as shown
in Figure 9, vertically disposed and spacially separated
perforated metal plates 41 may also be used to reduce
the brightness on the sign translucent faces 18 near the
luminaire. Still further, in yet another alternative
embodiment as shown in Figure 10, vertically disposed
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and spacially separated louvers 43 may also be used to
reduce "bright spots" on sign translucent faces 18.
Louvers 43 may also be coated preferably with a heat
resistant material to improve their efficiency in
blocking light.
Referring now to Figure 6, which is a top
sectional view of the side sectional view of the interi-
or of the luminaire 12 pictured in Figure 5, there i8
illustrated the action of vertical biasing prisms 33, as
shown in Figure 6, located on the inside surface of the
sides 38 of the refractor 24 to reduce penetration of
light through the refractor sides 38 and redirect light
from the light source 20 laterally along the translucent
faces 18 of the sign 10.
15The action of the vertical biasing prisms
located on the inside surface of the sides 38 of the
refractor 24 cooperate with the horizontal reflecting
. prisms 37 on the outside surfaces of luminaire refractor
24 to effectively avoid the appearance of a bright spot
20on the portion of the sign translucent face 18 adjacent
the light source 20.
The horizontal reflecting prisms 37 on the
outside of the sides 38 of the refractor 24 are posi-
tioned so their axes are coincident with the light rays
25inside the glass. Since there is normally some rounding
on each peak and valley of the prisms 37, this rounding
will allow light to go directly through and cause
brightness on the face of the sign were it not for the
action of the vertical biasing prisms 39. Since each
;~ 30peak and valley of the vertical biasing prisms 39 will
- also be rounded and to illustrate the point, assuming
for example, the rounding of each prism to be approxi-
mately 10~, the inside vertical prisms coupled with the
outside horizontal prisms will reduce the amount of the
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light going directly through the refractor to 10% times
10% or 1%.
Another function of the internal biasing
prisms 39 is to allow as much greater acceptance angle
for the outside reflecting prisms 37. With light going
directly into a reflecting prism, there is only a range
of +/- 3 degree~ for total internal reflection. If the
source is larger than this +/- 3 degrees, than the prism
will start to "leak." Accordingly, with the action of
the internal vertical biasing prisms 39 biasing the
light in a direction parallel to the reflecting prism
path 37, the angle of the light with respect to the
normal of the reflecting surface becomes much greater
and therefore total reflection occurs from a much larger
source.
From the foregoing, it can be seen that there
has been provided by the subject invention a new and
. improved internally illuminated sign in which a lumi-
naire mounted at the lower border or periphery of a sign
utilizes a reflector to di~tribute light in a fan-shaped
pattern laterally along the sign and parallel to the
face of the sign, and a refractor to intercept light and
redirect it to provide a uniform luminance on the sign
face while at the same time blocking direct source light
from penetrating the sides of the refractor and produc-
ing hot spots on the sign face.
It should be obvious that although a preferred
embodiment of the invention has been described, it is
-~ possible to make changes to certain specific details of
the assembly without departing from the spirit and scope
of the invention.
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