Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to the illumination of signs
which display a message or pattern.
In Canadian Patent No. 1,310,186 issued November 17,
1992 to Frederick Dimmick (who is also the inventor of the
invention of the present application), there was disclosed
and claimed a sign comprising at least one light pipe
carrying at least on light emitting diode contained in one
end and directed towards another end of the light pipe. The
invention disclosed and claimed in Canadian Patent No.
1,310,186 was intended to overcome many of the problems and
disadvantages of the prior art. For example, the sign of
Canadian Patent No. 1,310,186, comprising LEDs embedded in
light pipes may reduce the maintenance and operating costs
of signs in comparison with those of signs lit by
incandescent or fluorescent or other light sources.
At the time that the invention of Canadian Patent No.
1,310,186 was made, it was only possible to produce LEDs of
relatively restricted illuminating power. At that time, for
practical purposes, the maximum illumination obtainable from
the LED was in the order of 300 millicandela. Due to this
limitation, the light pipes of Canadian Patent No. 1,310,186
could only be produced in short lengths if they were to
provide bright illumination. For this reason, the invention
was ideally suited to signs involving lettering, a separate
light pipe being provided for each component of each letter.
While this provides advantages if the LED in one light pipe
fails, it is probable that the sign will still be readable,
it does make the short light pipe lower power LED system of
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Canadian Patent No. 1,310,186 less suitable for signs where
full background lighting is required.
Full background lighting may be desirable in some or
all of the following circumstances:
1. For signs of which the front screen may be
interchangeable to vary the message given. For example,
such a sign might indicate store specials which vary from
week to week.
2. Signs having non-standard planar shape or signs having
three-dimensional shape. Such signs have presented problems
in uniform lighting when utilizing rigid straight lighting
pipes spaced apart in parallel relationship.
3. When variably coloured lighting and other attention
getting means such as flashing or varying illumination
intensity of specific colours or areas of the sign is
required from one part of the sign to another independent of
any lettering or indicia on the sign. In this case, the
signs may be conventional rectangular planar signs or they
may be planar signs of other shapes or three-dimensional
signs.
The use of neon or fluorescent or incandescent bulbs is
commonly used to overcome some of the problems. However,
neon and fluorescent tubes must be manufactured into any
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unconventional shape and, should the tube fail, the whole
sign may be extinguished. Incandescent bulbs utilize large
amounts of electricity and take up an appreciable amount of
space. Moreover, they produce heat which may be undesirable
in many circumstances.
The present inventor has addressed the problems and, in
particular, has addressed the problem of making the lighting
system of Canadian Patent No. 1,310,186 utilizing LEDs more
suitable for a wider variety of signs especially those
requiring generalized background light. Moreover, the
inventor has tried to provide signs which require little
thickness or depth from front to back and so may be suitable
for positions where physical projection is undesirable and
where sign of very low weight may be required or desired.
Also the inventor has tried to provide a sign which the
parts, particularly the light parts are quickly and easily
adjustable in position, and removable and interchangeable.
According to the invention there is provided an
illuminatable sign comprising a front screen having
translucent portions defining sign indicia; a back panel
spaced from the front screen by at least one spacer; light
modules arranged adjustably and removably between the screen
and the back panel to provide illumination through said
translucent portions; and means to connect said modules to a
source of electrical power in such a manner that they are
individually disconnectable and removable from said source
and/or adjustable in position between said screen and said
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back panel. It is to be noted that, when used herein
"translucent" includes "transparent".
Preferably the modules comprise elongate bars carrying
light elements, the bars having an electrical connector at
each end for quick connection into and release from an
electric circuit for providing power to said light elements.
For example, each module may comprise an elongate
printed circuit board carrying light emitting diodes, the
printed circuit board having an electrical connector at each
end for snap fitting into an electrical circuit for
providing power to the light emitting diodes. Preferably
the printed circuit boards may be snapped into position in
the electrical circuit in a variety of different positions.
Conveniently the electric circuit includes a network of
at least one pair of power buses and a plurality of light
modules. The power buses may be conductive bars or wires
having dimensions to accept quick release connection of the
printed circuit board modules thereto. The conductive bars
or wires may be spaced apart by the distance equal to the
length of the printed circuit boards or equal to the
incremental repeated length of the circuit boards pattern
and snap connections or clip sockets may be provided on the
printed circuit boards at each increment repeat of pattern.
The clip sockets may, for example, be open ended slots
having an upstanding conductive fence. Such clip sockets
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themselves are believed to be novel. Alternatively the clip
sockets may be any conventional open ended clip socket.
Alternatively the means to connect the modules in such
a manner that they are individually disconnectable and
removable from the source, may be a prong and socket
connection. The socket may be a helical compression spring
about a bus wire as the source of electrical power. The
prong may extend from the printed circuit board and may have
a rectangular section and a tamped point. The dimension of
the helical spring and the prong may be such that, when the
prong is pushed into the spring to abut the bus wire, the
spring compresses to increase its diameter to allow passage
of the prong and tightens on the prong to hold it in contact
with the bus wire.
The prong may be formed from cold-rolled half-hard, 700
cooper - 30% zinc so that it may be bent as desired so that
each module is located at any desired angle to the bus wire.
The invention may provide simple, cost effective and
lightweight illuminated signs that have many features not
available in current sign fabrication, including both manual
and electrical means for:
1. Programming Features - the network or web of buses and
clip on modules creates a matrix which may best be described
as a macro hybrid integrated circuit, permitting unlimited
permutations for controlling brightness, colour changes and
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mixes, as well as selected area illumination, i.e. lighting
only the areas of the sign face which require illumination;
additionally overall or selected area flashing and
sequential lighting of characters, lines of text or
graphics, the illumination is by diffusion presented evenly
and not pixilated as with typical LED programmable signs.
2. Thin Design - The signs may be thin from front to back
because the LEDs do not require much space.
3. Energy Efficient - From 10 to 40 watts per square
metre.
4. Reliability - Low maintenance when lit with LEDs.
5. Versatile - Flexible wire buses and clip on circuit
board modules can accommodate virtually any shape requiring
illumination.
6. Safe Low Voltage Operation - Battery or eliminator
powered, because of low power required can be placed in
locations where hydro is unavailable, powered by solar array
and batteries.
7. Down Light - It is possible to provide a "down light"
which is desirable in many locations, for example Exit
signs.
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One or more modules may be connected in electrical
parallel between the conductive bars or wires although the
physical distribution may be parallel or in other patterns.
For example, the conductive bars or wires may be concentric
circles and the modules may extend radially between them.
Embodiments of the invention will now be described by
way of example with reference to the drawings in which:
Figure 1 is a perspective view of a sign in accordance
with the invention;
Figure lA is a perspective view of an alternative sign
in accordance with the invention;
Figure 2 is an exploded view of the sign of Figure 1;
Figure 3 is a perspective view from one side of a
lighting module comprising one printed circuit board of the
sign of Figures 1 and 2;
Figure 4 is a view from a perspective view from one
side of a lighting module comprising two end-to-end printed
circuit boards;
Figure 5 is a view of an alternative module;
Figures 6A and 6B show illuminated signs indicating the
positioning of lighting modules;
Figure 7 illustrates module such as that illustrated in
Figures 3 and 4 arranged for a planar curved sign.
Figure 8 shows lighting modules such as that
illustrated in Figures 3 and 4 arranged for a three-
dimensional cylindrical sign; and
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Figures 9A, 9B and 9C are sketches showing the
progression in adjusting the position of lighting modules
such as that shown in Figures 3 and 4 and interchanging a
module for another;
Figure 10 shows an enlarged view of a novel means for
attaching modules to the power buses;
Figures 11A, 11B and 11C show an embodiment of another
clip;
Figures 12A and 12B show an alternative novel means for
attaching modules to power buses; and
Figure 13 shows curved modules attached to power buses
by the attachment means of Figures 12A and 12B.
Figures 1 and 2 show a sign 10 having a front screen
12, a frame 16 and a back panel 18. Back panel 18 may be an
opaque panel or a second screen (and, optionally back panel
18) .
The front screen 12 has a translucent portion 20
through which light can shine. The translucent portion 20
may be an aperture or may be glazed by glass or translucent
plastic material. This transparent portion 20 may be the
lettering of a message or may be illustrative.
The screen 12 and the back panel 18 which have co-
extensive perimeters are connected together by frame 16
which also acts as a spacer 22 between them. It is, of
course, possible to provide a frame covering the edges of
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screen 12 and back panel 18. In this case separate spacers
22 will be desirable. This situation is shown in Figure lA.
The back panel 18 carries on its front surface the
circuitry necessary to provide illumination to shine through
the transparent portions 20 of screen 12.
The circuitry for providing the illumination may
comprise lighting modules 24 and uncovered conductive
circuit wires 30, 32 spaced apart from one another. Each
module comprises an array of LEDs arranged to connect one
terminal of each LED to a positive terminal of the module,
and the other terminal of each LED to a negative terminal of
the module. The positive and negative terminals 26, 28 are
respectively electrically connected to power buses, i.e.
wires 30, 32 to be slidable thereon without losing
electrical contact.
As especially shown in Figures 3 and 4, the basic
module 24 may comprise a single row of six LEDs 34 mounted
on an elongate printed circuit board 36. The circuitry may
be modified by placement of ballast resistors for either 6
or 12 volt DC operation. For 24 volt DC operation two end-
to-end modules as shown in Figure 4 may be used. The
printed circuit board 36 is such that the first terminal of
each LED series group is connected to the positive terminal
26 of the module and the other terminal of each LED series
group is connected to the negative terminal 28 of the
module.
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The extended module of Figure 4 shows that the
circuitry may be repeated continuously on a circuit board,
limited only by the ability of the circuit trace 31
connectors, and supply buses 30, 32 to carry the required
current. In the circuit board industry at present, boards
over 2 feet are not produced in a cost effective manner
since there has been little requirement for such boards.
Boards four feet long would be preferable, as this
measurement is typical in sign manufacture. Such boards may
comprise eight basic, continuously connected 6 inch modules,
complete with LED lamps and friction clips. Thus the board
is provided in convenient increments to accommodate
virtually any size requirement for illumination.
Another advantage of boards including multiple modules
is that the intermediate clips provide taps for power supply
to inserted shorter boards for increased intensity or
addition of colour to selected area (see Figure 7). Such
increased intensity or addition of colour may illuminate
varying size graphics. Also longer boards maybe used for
upper case letters and short boards may be used for lower
case letters (see Figures 6A and 6B).
It is, of course, clear that each module may have other
configurations, for example, that shown in Figure 5 or more
complex configurations.
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Conveniently, each novel terminal 26, 28 comprises a
conductive, open ended slot having respective conductive
fences 27, 29 to fractionally engage wires 30, 32. Thus, it
is possible to adjust the position of module 24 on wires 30,
32 by sliding the module along the wire. It is also
possible to remove module 24 from wires 30, 32 by
disengaging the wire from the clip slot 26, 28. The module
may then be replaced by an alternative module offering a
different colour of LEDs or to replace a failed module. The
sequence of events in adjusting the position of or changing
a module is best seen in Figures 9A, 9B and 9C and will be
described hereinafter.
Input wire terminals 30, 32 may be connected to an AC
power source through a bridge rectifier capacitor and
voltage regulator to provide a DC power source of, for
example, 12 volts. However, one possible advantage of the
present system is that it may be run from an AC source using
a standard AC to DC adaptor. Flashing circuitry may be
interposed between the DC power source and all or selected
portions or sign electrical distribution system to attract
attention or to significantly reduce power consumption while
operating in a continuous mode or in conjunction with
sensing devices to enable the sign only when traffic is
present to observe the message. If the sign is to be used
in a region where the electricity supply is unreliable or
unavailable, it may be powered directly from a 12 volt
battery, for example, in automotive and marine vehicles in
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which it may be powered from an internal 12 volt power
point.
To provide background illumination which is generally
regular over the area of the sign the illuminating power of
the LEDs and their spacing apart on each module is carefully
chosen. Moreover, the number of modules and their pattern
and spacing is also important.
For a rectangular sign 10 as shown in Figures 1 and 2
having a dimension of 16 inches by 96 inches, it may be
suitable to use 4 modules 24 each comprising a single row of
LEDs on an elongate circuit board 36, the LEDs 34 each
having a power of 8 - 9 candela and spaced apart by say 3
inches along the length of the circuit board 36. Such a
sign may have a total wattage of 14 watts.
Figures 6A and 6B show examples of layouts for the
lighting modules. Figure 6A shows a combination of long and
short boards for different areas of the sign. Figure 6B is
an example of a two sided sign in which, not only front
screen 12, but also back panel 18, has translucent portions.
The text may be one colour and the graphics may be two
colours. The graphic outlines are the same colour as the
text provided by the longer modules 24F. The body of the
graphic is second colour, the short modules 24E provide the
second colour and they share the same electrical feed as the
balance of the modules but have a separate return bus which
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can be used to enable independent flashing of the graphic
logo.
Figure 6C shows an Exit light having a down light. The
front screen is lit by modules 24G which might, for example,
show red light. It also has a downwardly directed light
which shows through an aperture 60 in a floor 41 of frame
42. The downwardly directed light from modules 24H might be
orange/amber.
The angle of dispersion of the illumination from each
LED may advantageously be in the region of 23° for the
exemplary sign referred to above. It is clear, however,
that the choice of the angle of dispersion for each LED 34,
the illuminating power of each LED 34 and their spacing
apart on the module and the number and pattern of the
modules 24 is a matter of choice dependent upon the
background lighting required for the sign. The colour, or
colour variation across the sign may also be a matter of
choice depending on the colour of LEDs chosen for each
module and the pattern and spacing of the modules.
Again, for the exemplary sign shown in Figures 1 and 2,
the modules may be arranged in a pattern and spacing shown,
i.e. parallel to each other and to the sides of screen 12
and back panel 18. Thus the two outermost modules 24A and
24D may be arranged with their circuit boards 36 aligned
with side edges of screen 12, the planes of the circuit
boards being at right angles to that of screen 12 and the
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light from LEDs 34 being directed inwardly across the screen
12 and back panel 18. Inner modules 24B and 24C may be
parallel to modules 24A and 24B and the LEDs 34 on those
modules 24B and 24C may be directed across the sign in
either direction. For most purposes it is not desirable to
place modules 24B and 24C with the backs of their circuit
boards 36 close together with their LEDs 34 directed towards
the sides of the sign. This may make an undesirable shadow
down the centre of the sign. For regular background light
it may be desirable to space the modules 24 evenly. For
very regular distribution of light in the sign it may be
that the inner modules such as 24B and 24C have LEDs 34
directed to both sides of the printed circuit board. In
this case the printed circuit will be partially on one side
of the board and partially on the other side of the board.
Such a bi-directional module is shown in Figure 5.
The modules 24 may be mounted on back panel 18 by means
of the power buses 30, 32 which may be provided in the form
of strong wires between side members 14 of the frame 16.
Wire 30 stretches between side members 14 near the top of
the frame 16 and wire 32 stretches between members 14 near
the bottom of the frame 16. Modules 24 are provided with
connectors for wires 30, 32 comprising conductive open ended
slots having respective fences 27, 29 forming friction clips
at each end of the elongate printed circuit board 36, and
intermediate clips in the slots at the regularly repeated
intervals along the board. These clips 27, 29 attach
respectively to wires 30, 32 to form a good electrical
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connection therewith. Each module 24 may be independently
clipped into place on the wires 30, 32 and may be adjusted
along the length of the wires once in position, or branched
from adjacent modules with additional wires 30A, 32A. An
alternative form of connection for the modules is to provide
a tubular socket through each end. Wires 30, 32 are
threaded through the sockets Such modules having tubular
sockets may be adjusted along the length of the wires 30, 32
but can not be removed from them unless a free end of wire
is made available so that the modules 24 may be unthreaded
therefrom.
For simplicity, the spacers may be formed integral with
the frame as a structural spacing frame 16 between the
screen 12 and the back panel 18. This is best shown in
Figure 2. The back panel 18 may be secured to the frame 16
by screws or other means and the screen 12 may be releasably
attached to the frame 16 by hook and loop fastenings such as
Velcro (Registered trademark) or other releasable fastening
means so that it may be easily removed and replaced with a
different screen when desired. The wires 30, 32 extend
through the sides of the frame to terminate one end in an
insulated fixing 40 and, at the other end, in a socket 38
for an AC to DC 12 volt adaptor. The frame 16 is
conveniently made of rigid plastic material such as PVC
which provides some insulation for wires 30, 32.
When frame 16 acts as a spacer between the screen 12
and back panel 18 as just described, it may be preferable to
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provide a light over-frame 42 enclosing the edges of screen
12 back panel 18 and frame 16. This is particularly useful
when the sign is to be located out of doors to prevent water
ingress. Even when the sign is to be located indoors, such
an over-frame 42 may provide an aesthetic appearance.
The arrangement of elongate modules 24 so far
described, such modules being adjustable on conducting wires
30, 32 is of particular benefit where non-rectangular signs
are to be provided.
Figure 7 shows a circular sign in which wire 30 extends
around the inner perimeter of the sign 10 inside frame 16
and wire 32 forms a small circle near the centre of the
sign. Modules 24 similar to the elongate modules already
described are arranged radially between wires 30, 32. The
positioning of the modules on the wires is adjustable for
fine tuning of the illumination by sliding the modules on
the wires as previously described. Moreover, if the modules
are provided with clip slots 40, the modules may be
interchanged or replaced as desired by clipping them on and
off wires 30, 32. Figure 7 also shows power buses 30A, 32A
to provide increased illumination of modules 24H.
Figure 8 shows a cylindrical sign in which wire 30
extends around one end of the cylinder and wire 32 extends
around the other end of the cylinder. Elongate modules 24
extend between the wires around the outside of the cylinder.
In this case, the frame 16 comprises a component 16A at one
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end and another component 16B at the other end. The screen
12 is cylindrical and may be slid over circular component
16A, 16B to be held in either a force fit or by releasable
attachment such as Velcro. To provide a convenient
connecting socket for an AC/DC adaptor, a connecting wire
may be led from end of the cylinder to the other from wire
32 to the end of the cylinder adjacent wire 30. It is then
convenient to provide a socket in component 16A adjacent
wire 30.
The modules, each comprising LEDs in series are
themselves connected in parallel in an electrical circuit
powered from the AC supply and including a bridge rectifier
capacitor and voltage regulator 44 to provide direct current
across the LEDs. The rectifier/regulator may be located
inside the frame on a printed circuit adjacent the inside
frame edge. In this case the socket 38 for an AC/DC 12 volt
adaptor may be replaced by a two or three pin conventional
socket for AC supply.
When it is desired to change a module or adjust its
position the sequence of events may be explained with
reference to Figures 9A, 9B, and 9C.
Figure 9A shows a rectangular sign having four elongate
modules 24 arranged spaced apart in equal intervals across
the sign from one side to the other.
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For example let us suppose that it is desired to
provide greater illumination at one side of the sign than at
the other. Then the screen 12 (not shown in Figures 9A, 9B
and 9C for simplicity) is removed and the modules are slid
for example, into the position shown in Figure 9B.
If a module 24 fails (or if a different colour is
desired), the appropriate module is removed simply by
pulling it forwardly in the direction of the arrow shown in
Figure 9C to disengage clips 27, 29 from wires 30, 32. The
offending module may then simply be lifted away and another
may be put in its place.
It will be appreciated that the use of LEDs as lighting
units mounted on elongate narrow printed circuit boards may
allow for minimum space between screen 12 and back panel 18.
This may permit the construction of a sign which is very
thin from front to back. Such a sign may appear to be
almost completely flush with a wall to which it is mounted.
Nevertheless, it is to be commented that the invention is
not limited to the use of LEDs and printed circuit boards.
It is quite possible that the modules may be lighting bars
utilizing incandescent or fluorescent units provided that
such modules are provided with terminals which will snap fit
onto carrier conductive bars or wires to be slidable thereon
without loss of electric contact so that a sign having
adjustable interchangeable parts is provided.
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Figure 10 shows an end of a printed circuit board 36
having a slot 46 in one end and a novel conductive open
ended clip 26A at one end. The clip 26A has two gullets 48
for holding bus wires 30, 30A with flared lips 50 at front
edge to ease onto wires 30 or 30A, a broad channel 52 in the
centre to fit snugly into circuit board slot 46 with sides
tapered to top and bottom edges to provide spring grip of
wire buses 30, 30A.
Figures 11A, 11B and 11C show an alternative embodiment
of a clip 26B. Clip 26B comprises a pair of curved
conductive straps 54 biased towards each other as shown in
Figure 11A and extending upwardly from extending tongue 56.
A possible advantage of the clip 26B is that it may be
positioned in locations according to choice with respect to
lighting module 24 (see Figure 11B). Tongue 56 may be bent
a right angles as shown to make contact with the printed
circuit board 36 or may be bent at other angles.
Figures 12A and 12B show an end of a module 36 having a
prong 58 at one end. Prong 58 is of rectangular cross
section and has a ramped tip 60. Prong 58 is conveniently
formed of cold-rolled, half-hard, 70% copper - 30% zinc.
The prong 58 may be fixed to the module by a bent over end
68 through circuit board and soldered into position by means
of a soldered boss 70.
A helical compression spring 62 is located about bus
wire 64 which may be of tinned copper. The diameter of the
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uncompressed spring 62 is such that, when the tip 60 of
prong 58 is pushed into it, it compresses to increase its
diameter to allow passage of the prong 58 into the spring
alongside bus wire 64.
The spring 62 is biassed to grip the prong 58 to hold
it firmly against bus wire 64. Whenever the spring is
compressed by axial pressure on the prong 58 along bus wire
64, the diameter of the spring increases to allow it to
slide along bus wire 64 to adjust the position of module 36.
When axial pressure on the prong 58 is relaxed the bias of
the spring 62 allow it to grip the prong firmly. The grip
may be sufficient to make reliable, vibration proof contact
with the bus wire.
The prong 58 may be bent at the point it leaves the
module 36 (see Figure 12B) to enable the orientation of the
module to be altered in relaxation to the bus wire 64.
Figure 12B shows a 90° bend which places the LEDs 34
perpendicular to the bus wire 64 rather than parallel to it
as shown in Figure 12A.
The modules 36 may be formed from glass reinforced
epoxy resin and may, themselves, be bent into shapes to
direct the LEDs inwardly or outwardly of the curves (see
Figure 13). Such bent circuit boards may have a prong 58 at
each end for connection to bus wires. The diameter of the
bus wires, the cross section of the prong 58 and the
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diameter of the spring 62 may be varied for optimum grip and
sliding of the spring on the bus wire.
