Note: Descriptions are shown in the official language in which they were submitted.
CA 02635620 2008-06-23
LAMP RETAINING SYSTEM FOR TRAFFIC SIGNALS
FIELD OF THE INVENTION
The invention relates to traffic signals and, more particularly, to the lamp
portions
of traffic signals.
BACKGROUND OF THE INVENTION
Traffic signals have been used for many years. In North America alone, it is
estimated that there are over 330 thousand signaiized intersections. For
municipalities
and other road authorities, installation and maintenance of traffic signals
can be a major
budget item.
One form of traffic signal uses an incandescent bulb that is threaded to a
lamp
socket (or base) installed in a reflector assembly within a back recess of the
signal
housing where the bulb accesses a power source. The light bulb's white light
is
transmitted through a translucent lens that is colored (usually solid red,
yellow, or green).
This dome-shaped lens is installed in the front window of the housing. It is
held in place
in the window by a set of (usually four) mounting brackets (or "lens clips").
The
mounting brackets are substantially flat stamped pieces of metal (usually
stainless steel
or aluminum) that are, more-or-less permanently, screwed onto the front door
of the
traffic signal housing (usually one in each corner). The mounting bracket
extends over
the circumferential lip of the lens to hold the lens in place.
To change the light bulb, a technician opens the traffic signal housing,
unthreads
the burnt out light bulb from the socket, screws in a new light bulb, then
closes the
housing. This is a relatively simple procedure. However, to replace the lens a
technician needs to unscrew each of the mounting brackets (trying not to drop
or lose
the tiny screws or the brackets themselves), remove the broken or damaged
lens, then
replace the lens with a new one, reattaching the mounting brackets by re-
fastening the
screws with a screwdriver (while holding the lens in place).
These replacements are typically done by a technician on-site. The technician
is
in an awkward position - raised up in a "bucket" of a crane truck. The buckets
tend to
sag and sway in high winds. The technician must work quickly and carefully.
The traffic
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signal usually needs to be disabled to carry out this maintenance work, so
time is of the
essence. Since the signal is outdoors, the technician may also be working in
less than
ideal weather conditions or under cover of night. He may further be using
gloves to do
the replacement, adding to the difficulty. All of these factors make simple
operations
more difficult.
A recent development is the use of light emitting diodes (LED's) in traffic
signals.
Gradually, road authorities in various jurisdictions have been switching over
from the
conventional incandescent light-based traffic signals to LED-based traffic
signals, which
last longer and require less power than incandescent light bulbs. It is
estimated that
roughly 75% of the traffic signals in North America have been converted to
LED. One
way this change has been implemented has been by retrofitting signals designed
for
incandescent-type lamps to use an LED lamp kit.
LED lamp kits are structured differently than traditional incandescent lamps.
Instead of having a separate lens, bulb, socket/reflector and power supply,
the LED lamp
kit is a self-contained unit. All of these parts are in one package. An array
of LED bulbs
is mounted on a circuit board. The circuit board is connected to a power
supply. A
colored or clear dome lens is attached over the circuit board. All of these
parts are
contained in a single sealed "kit". One standard type of kit is a round disc-
shaped kit
(there are also square and rectangular kits). The diameter of the round kit is
commonly
8 inches (200 mm), 12 inches (300 mm) or 16 inches (400 mm). To retrofit the
incandescent housing, the socket and reflector are removed, the lens is
removed, and
the LED lamp kit is simply installed in place of the lens. The lamp kit is
attached using
the same screw-fastened mounting brackets that were formerly used to hold the
lens in
the incandescent model.
A problem with this retrofit is that the LED lamp kits must be replaced at
fairly
frequent intervals. Unlike the lenses of the incandescent model (which were
infrequently
- if ever - replaced after installation), the LED lamp kits are routinely
swapped out for
fresh kits approximately every 3-5 years. Therefore, the technician is
confronted with
the hassles of dealing with the screw-fastened mounting brackets much more
frequently.
It would be desirable to provide a system whereby either lenses or full LED
lamp
kits can be easily replaced in a traffic signal without the need for
detachable parts or
tools, allowing the technician to carry out the replacement simply and
effectively.
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SUMMARY OF THE INVENTION
According to a first aspect of the invention, a locking clip is provided for
attaching
a lamp assembly to a traffic signal housing. The housing has a front wall
defining a
window through which the lamp assembly is visible. The clip has a first fixed
portion and
a second movable portion. The first portion is attachable to the housing
proximate to the
window. The second portion is connected to the first portion and movable
relative
thereto, and is releasably lockable to the first portion or to the housing for
retaining an
edge of the lamp assembly. The clip secures the lamp assembly to the front
wall of the
housing allowing it to be visible through the window. In one embodiment, the
first and
second portion lock to each other, and the clip retains the edge of the lamp
assembly by
urging it against the housing.
The clip is a "locking" clip in the sense that it is capable of securely
holding. The
clip may act to create a releasable lock against the housing of the traffic
signal or it may
lock to itself (i.e. the first and second portions lock together). The secure
holding may be
provided by simple friction.
The lamp assembly is intended to encompass an LED lamp kit, or an
incandescent-type dome lens with attached gasket, or another assembly (not
necessarily including a light bulb) that has a light-transmitting structure.
Preferably, the second portion is hingedly joined to the first portion and
folds over
the first portion for locking.
In the alternative, the second portion may have a sliding connection to the
first
portion. Thus, the second portion has:
a first slide position in which the second portion is locked to the first
portion or to the housing for securing the lamp assembly, and
a second slide position in which the second portion is unlocked from the
first portion or from the housing for releasing the lamp assembly.
In the further alternative, the second portion may have a rotatable connection
to
the first portion. Thus, the second portion has:
a first rotated position in which the second portion is locked to the first
portion or to the housing for securing the lamp assembly, and
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a second rotated position in which the second portion is unlocked from
the first portion or from the housing for releasing the lamp assembly.
Returning to the preferred (hinged) embodiment, the clip may further comprise
a
locking wedge on one of the second portion or the first portion and a locking
slot on the
other of the second portion or the first portion for releasably receiving the
locking wedge.
Preferably, the locking wedge is on the first portion and the locking slot is
on the second
portion. The locking slot may further comprise a gripping edge, and the
locking wedge
may further comprise a gripping projection, allowing the gripping edge of the
slot to catch
on the gripping projection when the second portion and the first portion are
folded
together. Preferably, the locking slot is unlockable from the locking wedge by
pushing
on the locking wedge to uncatch the gripping projection from the gripping
edge.
Preferably, the locking slot is manually unlockable from the locking wedge.
The second portion and the first portion may be joined to each other by a
natural
hinge. For instance, a single piece of material may be integrally folded to
form a natural
hinge to form the main body of the clip.
Various materials are possible for the clip. The clip may be a plastic clip,
or a
metal clip, for instance, or the clip may be made of multiple materials in
different parts.
For instance, instead of a natural hinge, the clip may use a separate hinge
element. The
clip body (i.e. the first and second portions) may be made of plastic, while
the hinge
element may be made of metal. Various combinations are possible.
According to a second aspect of the invention, a traffic signal is provided.
The
traffic signal has a traffic signal housing with a front wall. A lamp assembly
fits within a
window in the front wall of the housing such that at least a portion of the
lamp assembly
is visible through the window. The lamp assembly is secured in the window by
at least
two locking clips installed on the front wall of the housing proximate to the
window. Each
clip has a first fixed portion and a second movable portion. The first portion
is attached
to the front wall of the housing. The second portion is connected to the first
portion and
movable relative thereto, and is releasably lockable to the first portion or
to the housing.
When locked, the clip acts to retain an edge of the lamp assembly.
The clips may be on an interior or exterior face of the front wall.
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It will be understood that the first portion of the clip may be "attached" to
the
housing by some mechanical means (e.g. screw, rivet, bolt, etc.), by adhesive,
or by
welded or soldered joint. The clip may also be integrally molded with the
housing.
According to a third aspect of the invention, a traffic signal is provided.
The
traffic signal has a traffic signal housing with a front wall. A lamp assembly
fits within a
window in the front wall of the housing such that at least a portion of the
lamp assembly
is visible through the window. The lamp assembly is secured in the window by
at least
two locking clips on the front wall of the housing proximate to the window.
Each clip has
a first fixed portion and a second movable portion. The first portion is
integrally formed
with the front wall of the housing. The second portion is connected to the
first portion
and movable relative thereto, and is releasably lockable to the first portion
or to the
housing. When locked, the ciip acts to retain an edge of the lamp assembly.
The clips may be on an interior or exterior face of the front wall.
According to a fourth aspect of the invention, a system is provided for
retaining a
lamp assembly in a traffic signal housing. The housing has a front wall with a
window
sized to fit the lamp assembly. At least one top and one bottom locking clip
are used to
secure the lamp assembly in the window of the traffic signal housing. Each
clip has:
a first portion attachable to the wall of the housing;
a second portion connected to the first portion and movable relative
thereto, the second portion being releasably lockable to the first portion or
to the
housing for retaining an edge of the lamp assembly to secure the lamp assembly
to the front wall of the housing allowing it to be visible through the window.
Preferably, the system further comprises fasteners for attaching the first
portion
of each clip to the wall of the housing. The fastener may itself be the "first
portion" that
attaches to the wall of the housing.
Preferably, the at least one top and one bottom locking clip comprises a pair
of
top locking clips and a pair of bottom locking clips. Preferably, the top and
bottom
locking clips are identical.
According to a fifth aspect of the invention, a lamp retaining system is
provided
for traffic signals having a housing having a front wall with a window and a
lamp
assembly sized to fit within the window. The system includes at least two
upper locking
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clips and at least two lower holding members. The upper locking clips and
lower holding
members cooperate to securely but releasably hold the lamp assembly in the
window of
the traffic signal housing. Each locking clip comprises:
a first portion attachable to the wall of the housing proximate to an upper
end of the window;
a second portion connected to the first portion and movable relative
thereto, the second portion being releasably lockable to the first portion or
to the
housing for retaining an edge of the lamp assembly to secure the lamp assembly
to the front wall of the housing allowing it to be visible through the window.
Each holding member comprises:
an attachment portion attachable to the wall proximate to a lower end of
the window; and
a holding portion extending outward from the attachment portion and
adapted to loosely grip an edge of the lamp assembly.
Preferably, the system further comprises fasteners for attaching:
(a) the first portion of the upper locking clips to the wall of the housing
proximate to the upper end of the window; and
(b) the first portion of the lower holding members to the wall of the
housing proximate to the lower end of the window.
According to a sixth aspect of the invention, a method is provided for
replacing a
lamp assembly in a traffic signal housing. The housing has a front wall
defining a
window in which the lamp assembly is mounted. The method comprises the
following
steps:
unlocking at least one locking clip that holds the lamp assembly by releasing
a
movable portion of the clip from either: (a) a fixed portion of the clip
mounted on or
integral with the front wall; or (b) the housing, without removing or
loosening the clip from
the housing;
removing the lamp assembly from the window;
replacing the lamp assembly with a replacement lamp assembly; and
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re-locking the at least one locking clip by closing or latching the movable
portion
to retain an edge of the replacement lamp assembly against the housing.
Preferably, the unlocking and re-locking steps are done by hand, without
tools.
All of the steps may be done by hand, without tools. Tools may be needed for
installation of the clip at the outset, but regular maintenance is preferably
tool-less and
does not require removal of the clip from the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1A is a perspective view of a traffic signal housing (prior art).
FIGURE 1 B is an inside view of the front wall of a conventional traffic
signal
housing showing conventional mounting brackets (prior art).
FIGURE 2A is an inside view of a front wall showing a first embodiment of the
present invention.
FIGURE 2B is a sectional view of Figure 2A.
FIGURES 3A, 3B and 3C are detailed views of closed (locked), opening and fully
open (unlocked) positions of the clip 40 shown in Figures 2A and 2B.
FIGURES 4A and 4B illustrate the removal of a lamp assembly 30 from traffic
signal housing 10.
FIGURE 5A is an inside view of a front wall showing a second embodiment of the
present invention (with slide locking clips 40A).
FIGURE 5B is a detailed view of slide locking clip 40A shown in FIGURE 5A with
illustrated movement.
FIGURE 5C is a cross-section along line A-A of FIGURE 5B.
FIGURE 6A is an inside view of a front wall showing a third embodiment of the
present invention (with rotatable locking clips 40B).
FIGURE 6B is a detailed view of rotatable locking clip 40B shown in FIGURE 6A
(in open position) with illustrated movement.
FIGURE 6C is a detailed view of rotatable locking clip 40B (in closed
position).
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DETAILED DESCRIPTION
A traffic signal has a box-like housing. The light (from an incandescent light
bulb
or array of LED bulbs) shines through a lens which is visible through a window
at the
front of the housing. One standard arrangement is shown in Figure 1A. The
front door
opens by uniatching side wing-nut closures. The front door, which is hinged,
can swing
open when the wing-nut closures are unlatched. With the front door open, a
technician
can access the light and power sources in the traffic signal.
The front door of the housing has a window. In a conventional arrangement, the
lens (for an incandescent light arrangement) or the LED lamp kit (with its own
self-
contained lens) is retained in the front window by inside-mounted mounting
brackets, as
shown in Figure 1 B. Each of these mounting brackets, commonly referred to as
a "lens
clip", is a substantially flat stamped piece of metal (usually stainless steel
or aluminum)
that is, more-or-less permanently, screwed onto the inside of the front door
of the traffic
signal housing (usually one in each corner).
To remove the lens or LED lamp kit retained using this arrangement, a
technician
must unscrew the screw and physically remove or substantially loosen the
mounting
bracket in each corner to release the lens or LED lamp kit. This is time-
consuming and
tricky for a technician working under less than optimum conditions.
The invention provides locking clips that can hold a lens or LED lamp kit but
can
also be released without removing the locking clip from the housing wall,
allowing the
lens or LED lamp kit to be easily removed and replaced.
One possible arrangement of such locking clips is shown in Figure 2A. Figure
2A
shows an inside face of the front wall 20 of the traffic signal housing 10.
The locking
clips 40 are positioned in two upper corners. These are fastened to, adhered
to, or
integral with the wall 20. As can be seen from the Figure, the clips 40 retain
an edge of
the LED lamp kit 30. Optional bottom holders 50 are also shown in this
arrangement.
Although an inside face of the front wall is shown, it is possible to mount
the clips on the
outside face, retaining the lens or LED lamp kit from the outside.
Figure 2B shows a sectional view of the front wall 20. In this case, an LED
lamp
kit 30 (having a built-in front lens 60) is retained by its edges 250 using
the upper locking
clips 40 and lower holders 50. The construction and specific features of the
holders will
be described in greater detail below.
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Various configurations of locking clips can be used to hold a lens or LED lamp
kit
(any kind of "lamp assembly") in the window of the housing, which can also be
released
without removing the locking clip from the housing wall. Three embodiments are
described and illustrated in the drawings. The first embodiment (a foldable,
self-locking
clip) is shown in Figures 3A-3C.
The clip 40 has, generally speaking, an upper portion 100 and a lower portion
90.
The upper portion is movable, while the lower portion remains fixed. The
portions meet
at a hinge 110. As shown, the hinge 110 may be a natural hinge, resulting from
the fold
of the two portions. Alternatively, a separate hardware piece may be used for
the hinge
(not shown). The clip 40 is attached to the wall 20 near the window 70,
preferably so
that it folds (closes) towards the window with the upper portion overhanging
the window
slightly. (The lower portion preferably does not extend into the window 70.)
The clip
may be fastened to the wall 20 using a conventional fastener (e.g. in screw
hole 120).
Alternatively, it may be adhered to or riveted to or molded with the wall 20.
On the lower portion of the locking clip 40 as shown, a locking wedge 130 may
be provided. The locking wedge is preferably a resilient bent tab. On the
upper portion
of the locking clip, a locking slot 160 may be provided. Generally speaking,
the clip is
locked by interference between the locking wedge 130 and the locking slot 160.
The clip
in locked position is shown in Figure 3A. Specifically, the locking wedge 130
has a
gripping projection 140 which overlaps a gripping edge of the locking slot
160. The
gripping projection holds the gripping edge, retaining the upper and lower
portions of the
clip together. The locking wedge and locking slot may be positioned generally
behind
the center of the clips (toward the hinge). The front edge of the clip holds
the edge of
the lamp assembly (in this case, an LED lamp kit 30), securing the lamp
assembly within
the window 70 of the housing. The upper portion of the clip may have a cutaway
slot
180 toward the front edge 170 allowing the edge of the lamp kit to protrude
through. A
front reinforcement ridge 190 may further be provided which also bears upon
the edge of
the lamp assembly.
The locking clip may not lock in one single "click", but may have a graduated
locking with multiple possible locked positions. For instance, the wedge may
have
multiple teeth that lock against the locking slot (like a ratchet). This
adjustability may be
preferred to accommodate varying thicknesses of the lamp assembly edge.
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To release the locking clip, the locking wedge 130 is pushed back (i.e. toward
the
hinge 110). This uncatches the gripping projection 140 from the gripping edge
150 of
the locking slot 160. With the gripping projection and gripping edge
separated, the
upper portion 100 may be lifted without obstruction, as shown in Figures 3B
and 3C. A
corrugated thumb grip 200 may be provided to allow the technician to easily
push up the
released upper portion 100.
As shown in Figures 4A and 4B, once the locking clips 40 are released, the
lamp
kit 30 can be removed by hand from the housing (i.e. without tools). The lower
holders
50 are not locking clips as such. They are fixed (generally L-shaped) brackets
that are
fixed (by screw or another fastening means) to the wall. As shown in Figures
2A and
2B, they have a projecting edge 260 that overlaps the window 70 to passively
retain the
edges 250 of the lamp kit 30, like a ledge on which the lamp kit rests. To
remove the
lamp kit 30, the locking clips 40 are opened and the lamp kit 30 is tilted
slightly back (i.e.
away from the wall) at the upper edges and slid upwards out of the L-shaped
lower
holders 50.
To insert a replacement lamp assembly, the process is simply reversed. The
edge of the lamp kit is slid into the lower holders 50. The lamp kit is
positioned in the
window, preferably allowing the lens portion 60 to protrude out through the
window 70.
Then, the locking clips are locked by folding/closing the upper portions 100
of the clips
down and over the lower portions 90. The natural springiness of the locking
wedge 130
causes the gripping projection 140 and the gripping edge 150 to automatically
catch,
locking the clip together with the upper portion 100 overhanging and retaining
the edge
of the lamp kit. The lamp kit 30 fits within the cavity 80 of the housing 10.
Once the
replacement lamp kit is installed, the front door can be closed and the side
wingnut
closures can be reattached to secure the housing in a closed position. The
housing 10
is preferably sealed around the edges of the door and around the juncture
between the
window 70 and lamp kit 30.
Figures 5A-5C and 6A-6C illustrate two other possible embodiments of locking
clips for the same purpose.
Figures 5A-5C show a slide locking clip 40A embodiment. Instead of having
upper and lower portions that fold together to interlock, the clip 40A may use
a slidable
body portion 210 with a (preferably longitudinal) slot 220. The body portion
210 slides
relative to a fixed element 230 (which may be a rivet, pin, screw, etc.) to
lock and unlock
CA 02635620 2008-06-23
the clip. The body portion has a forward edge 240 that overhangs the window 70
to
retain the edge 250 of the lamp kit 30 when the clip is in the locked
position. To unlock
the clip, the body portion is slid away from the window (in this case,
backwards), freeing
the edge of the lamp kit. The "locking" is simply provided by the frictional
engagement
between the lamp kit and the front edge 240 of the body portion 210.
Alternatively, the
slide locking clip 40A may have a lower portion (not shown) that the body
portion 210
slides upon. The lower portion is a fixed portion, which stays in place while
the body
portion is movable. The lower portion and body portion may lock together with
locking
features (such as a projecting dimple which interlocks with a cavity) on
opposing
surfaces of the body portion and the lower portion.
Different shapes of body portions and lower portions are possible. One
possibility is to use a flanged body portion that is nested/snapped into a
trough-shaped
lower portion. The flanged body portion would slide along the trough for
locking and
unlocking. The body portion stays attached to the lower portion by side tabs
in the
trough that overhang a widened flange on the bottom of the body portion. This
arrangement of tabs/flanges allows the body portion to move along the path of
the
trough without coming out.
Figures 6A-6C show a rotatable locking clip 40B embodiment. The clip 40B uses
a pivoting (rotating) body portion. To unlock the clip, handle 280 may be used
to turn the
clip about fixed pivot point 290 on a pin/fastener (not shown) to swing the
forward edge
300 away from the window, freeing the edge of the lamp kit. The clip may be
designed
to swing to the side in one direction or in either direction, or may swivel in
a 360 degree
circle. The rotatable locking clip 40B may have a lower portion (not shown)
that it
rotates upon (i.e. above). Locking features (such as a projecting dimple which
interlocks
with a cavity) may be provided to retain the upper and lower portions and to
assist in
locating the centered position at which the lock is most fully engaged. The
rotatable
locking clip may alternatively use a trough design similar to the slide
locking clip.
The locking clip in the slide or rotatable form may also include a spring or
other
biasing mechanism to provide constant downward pressure on the moving portion.
The
thickness of the edge of the lamp kit tends to push the movable portion of the
clip
upward. The spring would act to neutralize that tendancy.
The foregoing description illustrates only certain preferred embodiments of
the
invention. The invention is not limited to the foregoing examples. That is,
persons
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skilled in the art will appreciate and understand that modifications and
variations are, or
will be, possible to utilize and carry out the teachings of the invention
described herein.
Accordingly, all suitable modifications, variations and equivalents may be
resorted to,
and such modifications, variations and equivalents are intended to fall within
the scope
of the invention as described and within the scope of the claims.
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