Traffic signal having electronically reconfigurable LED array
OwnerMichael C. Hutchison, Kevin Ovensinventors
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Abstract
A reconfigurable LED array (22) having LED sets (26, 28, 30) in series with a main LED array (24). The LED array (22) is controlled as a function of the operating DC voltage such that as the operating DC voltage level drops, selective ones of the LED strings are shunted so that the remaining LEDs of the array (22) are operational. The operational LEDs are PWM controlled such that the overall light intensity generated by the operational LEDs meets DOT requirements. The LED sets (26, 28 30) are connected in series with the main LED (24) as is stacked logic (62, 64) along with a voltage regulator (60).
Claims20
A light apparatus comprising:
- a first rail having a first voltage;
- a reference node having a reference voltage;
- a first set of LEDs coupled to said reference node;
- a second set of LEDs coupled between said first LED set and said first rail;
- and
- a control circuit selectively controlling said second set of LEDs as a function of said first voltage relative to said reference voltage.
A method of operating a LED apparatus including a plurality of LED sets coupled in series between a reference voltage and a rail voltage, comprising the steps of:
- selectively powering the sets of LEDs as a function of the rail voltage with respect to the reference voltage.
Dependencies are inferred from the claim text.