Communications: electrical – Visual indication – Using light emitting diodes
Reexamination Certificate
1999-06-03
2001-07-31
Hofsass, Jeffery (Department: 2736)
Communications: electrical
Visual indication
Using light emitting diodes
C340S912000, C040S550000
Reexamination Certificate
active
06268801
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to Light-Emitting Diode (LED) lamps for traffic signal lights, and more particularly to an improved retrofit method for replacing conventional light bulbs in traffic signal lights with LED lamps, including 12 and 8 inch round traffic signal lamps, pedestrian signs, hand signs, arrow signs and signs with messages.
BACKGROUND OF THE INVENTION
Light emitting diode (LED) lamps have been developed to replace conventional incandescent or fluorescent lamps for reducing electrical and maintenance costs, and for increasing reliability. LED lamps consume less electrical energy than conventional lamps while exhibiting much longer lifetimes. Such LED lamps typically include a power supply and a plurality of LEDs mounted on a flat or curved surface.
One growing use of LED lamps is the replacement of incandescent light bulbs in traffic signal lamps. A common conventional traffic signal lamp is illustrated in
FIGS. 1 and 2
, and includes a housing
1
, a front door plate
2
, a lens
3
, a reflector
4
and an incandescent light bulb
5
. Retainers
6
affix the lens
3
to the front door plate
2
, which opens via hinges
7
to allow access to the interior of the housing
1
. Light bulb
5
screws into electrical socket
8
, which is electrically attached to a terminal strip
9
, which in turn receives its power from the traffic signal controller.
It is known to replace the incandescent light bulb
5
with an LED lamp, along with the lens
3
since it is designed for the output of an incandescent light bulb. In a conventional traffic signal lamp retrofit procedure, the lens
3
, light bulb
5
, reflector
4
and socket
8
are all removed, and an LED lamp module
10
is installed to the front door plate
2
to replace lens
3
, as illustrated in FIG.
2
. Wires
11
from the LED lamp module are connected to the terminal strip
9
.
The above mentioned retrofit method has several drawbacks. First, it is time consuming and labor intensive to remove the reflector
4
and socket
8
, and access the terminal strip
9
with new wiring. Because traffic is usually blocked in order to access traffic lights, time is of the essence. Second, in order to safely disconnect the socket connector wires from the terminal strip, and connect new wires from the LED lamp module
10
to the terminal strip, the power to the traffic signal must be temporarily turned off, which disrupts traffic flow through the intersection. Finally, once the retrofit is complete, it is not possible to put the original incandescent lamp back in the traffic signal lamp, for example in case a spare LED lamp is not available.
There is a need for an LED lamp and retrofit procedure for traffic signal lamps that is fast, simple, requires minimal labor to install, does not require turning the power off to the traffic signal, and allows reinstallation of the original incandescent lamp.
SUMMARY OF THE INVENTION
The present invention solves the aforementioned problems by providing a method of replacing a conventional traffic signal lamp with an LED lamp that is quick, simple, uses minimal labor, and can be safely performed with the power to the traffic signal left on. The existing incandescent lamp socket is left intact, so that the original lamp can be reinstalled back into the traffic signal lamp should the need arise.
The present invention is a method of retrofitting a traffic signal lamp with an LED lamp, where the traffic signal lamp includes a housing, a front door plate attached to the housing, a lens attached to the front door plate, a reflector in the housing, a threaded electrical socket connector in the housing, and a threaded light bulb connected into the socket connector. The method includes the steps of removing the lens from the front door plate, removing the threaded light bulb from the threaded socket connector, and affixing an LED lamp module to the front door plate. The LED lamp module includes a plurality of light emitting diodes, a power supply electrically connected to the plurality of light emitting diodes, wires extending from the power supply that terminate in a threaded electrical connector compatible with the socket connector. The method further includes connecting the threaded electrical connector of the LED lamp module to the threaded socket connector.
In another aspect of the present invention, an LED lamp module includes a housing, a plurality of light emitting diodes, a power supply disposed in the housing and electrically connected to the plurality of light emitting diodes, and wires connected to the power supply. The wires extend from the housing and terminate in a threaded electrical connector.
Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.
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Gray Cary Ware & Freidenrich LLP
Hofsass Jeffery
Leotek Electronics Corporation
Tweel , Jr. John
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