05457450 is referenced by 95 patents and cites 13 patents.

The present invention relates to an LED traffic signal light containing numerous LEDs and a voltage compensation circuit which allows the traffic light to operate over a wide range of input power voltages, while generating sufficient light intensity to control traffic at a highway intersection. The voltage compensation circuit achieves these objectives without substantially increasing the power consumption, overall cost, or failure rate of the LED traffic signal light. In the preferred embodiment, the voltage compensation circuit disables or rearranges a first and then a second set of LEDs in the traffic light, as the input power voltage drops below a first and then a second threshold voltage, so that the remaining LEDs will be driven by an increased current and generate a greater overall light intensity than if all of the LEDs were driven by the decreased current that would result from the decreased input power voltage. Also in the preferred embodiment, the LEDs are mounted on a printed circuit board, in a configuration generally corresponding to the shape of the traffic signal light.

Title
LED traffic signal light with automatic low-line voltage compensating circuit
Application Number
8/55512
Publication Number
5457450
Application Date
April 29, 1993
Publication Date
October 10, 1995
Inventor
David D Lewis
Yorba Linda
CA, US
Raymond E Deese
Corona
CA, US
Agent
Knobbe Martens Olson & Bear
Assignee
R & M Deese
CA, US
IPC
G08G 1/07
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