Solid state traffic light with predictive failure analysis
First Claim
1. A traffic control device, comprising:
- a housing;
a solid state light source disposed within the housing and having an array of LEDs generating a light output; and
a circuit predicting failure of said solid state light source based on a plurality of parameters at which said LED array operates.
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Accused Products
Abstract
An apparatus, system and method for determining when an LED used in traffic signal device will fail. The traffic signal apparatus comprises a housing, a solid state light disposed therein and having an array of LED generating a light output therefrom, and a circuit adapted to predict failure of the solid state light source based on a plurality of parameters at which the LED array operates. The method comprises the acts of sensing the light output generated by the LED array and sensing the ambient temperature thereby. These sensing acts are then followed by a calculating act wherein a time-average temperature value is calculated based on the intensity of both the light output and the ambient temperature. The calculating act is then followed by another calculating act wherein a time-average duty cycle value of the power source powering the LED array is determined. Next, a comparing act compares the time-average temperature value with the time-average duty cycle of the power source to advantageously determine when the LED will reach the end-of-life.
43 Citations
20 Claims
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1. A traffic control device, comprising:
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a housing;
a solid state light source disposed within the housing and having an array of LEDs generating a light output; and
a circuit predicting failure of said solid state light source based on a plurality of parameters at which said LED array operates. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for predicting the life span of an LED used in a traffic signal device having a controller and a power source, comprising the steps of:
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sensing a light output generated by an LED;
sensing the ambient temperature proximate said LED;
calculating a time-average temperature value using said ambient temperature;
calculating a time-average-duty cycle value of the power source used to drive said LED; and
comparing said time-average temperature value with said time-average duty cycle to determine when the LED will reach the end-of-life. - View Dependent Claims (8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20)
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12. A method of detecting failure of a solid state light source used in a traffic signal device, comprising the steps of:
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determining a plurality of parameters at which an LED operates within the traffic signal device; and
correlating at least two said parameters to predict when the light generated by an LED will fail.
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Specification