LED emitter for optical traffic control systems
A light emitter for a traffic control preemption system. The emitter includes a plurality of groups of infrared (IR) LEDs and a power source coupled to the groups of LEDs. A plurality of controlled current sources is coupled to the plurality of groups of LEDs, respectively. A controller is configured to trigger an IR light pulse pattern from the groups of LEDs and maintain a first level of IR radiant power from the groups of LEDs using individual control of respective current levels to the groups of LEDs in response to current sense levels from the groups of LEDs. The pulse pattern and first level of IR radiant power activate preemption in the traffic control preemption system.
1. A light emitter for a traffic control preemption system, comprising:
a plurality of groups of infrared (IR) LEDs, each group including one or more IR LEDs;
a power source coupled to the groups of LEDs;
a plurality of controlled current sources coupled to the plurality of groups of LEDs, respectively; and
a controller coupled to the plurality of controlled current sources, wherein the controller is configured to trigger an IR light pulse pattern from the groups of LEDs and maintain a first level of IR radiant power from the groups of LEDs using individual control of respective current levels to the groups of LEDs in response to current sense levels from the groups of LEDs, wherein the pulse pattern and first level of IR radiant power activate preemption in the traffic control preemption system.
2. The light emitter of claim 1 , wherein the controller is further configured, responsive to the current sense level from one of the groups of LEDs indicating to the controller that the one group of LEDs has failed, to increase the respective current levels to the groups of LEDs other than the failed group of LEDs.
3. The light emitter of claim 1 , further comprising a temperature sensor proximate the groups of LEDs and coupled to the controller, wherein the controller is further configured, responsive to a temperature level from the temperature sensor, to adjust the respective current levels to the groups of LEDs.
4. The light emitter of claim 1 , wherein the controller is further configured to trigger a subset of the groups of LEDs for each pulse of the pulse pattern, the subset including fewer than all of the groups of LEDs.
5. The light emitter of claim 1 , further comprising:
an IR sensor coupled to the controller, wherein the IR sensor is configured to receive the IR pulse pattern from the groups of LEDs and output a sensed level of IR radiant power of the groups of LEDs; and
wherein the controller is further configured to adjust respective current levels to the groups of LEDs in response to the sensed level of IR radiant power for maintaining the first level of IR radiant power.
6. The light emitter of claim 1 , wherein the controller is configurable with a parameter for specifying different levels of IR radiant power.
7. The light emitter of claim 1 , wherein the pulse pattern that activates preemption in the traffic control preemption system is a first pulse pattern, and the controller is further configured to trigger a second IR light pulse pattern from the groups of LEDs, and the second pulse pattern is different from the first pulse pattern.
8. The light emitter of claim 1 , further comprising a plurality of respective pulse energy storage devices, each coupled to the power source and to a respective one of the groups of LEDs.
9. The light emitter of claim 1 , wherein the controlled current source is a voltage controlled current source.
10. The light emitter of claim 1 , wherein the controller is further configured to count a number of pulses emitted by each group of LEDs and responsive to the count reaching a threshold, to increase the respective current levels to the groups of LEDs.
11. A light emitter for a traffic control preemption system, comprising:
a plurality of groups of infrared (IR) LEDs, each group including one or more IR LEDs;
a plurality of capacitors coupled to the groups of LEDs, respectively;
a power source coupled to capacitors;
a plurality of controlled current sources coupled to the plurality of groups of LEDs, respectively;
at least one trigger switch coupled to the controlled current sources; and
a microcontroller coupled to the at least one trigger switch, wherein the microcontroller is configurable with a parameter for specifying different levels of IR radiant power and is configured to trigger an IR light pulse pattern from the groups of LEDs and maintain a first level of IR radiant power from the groups of LEDs using individual control of respective current levels to the groups of LEDs in response to current sense levels from the groups of LEDs, wherein the pulse pattern and first level of IR radiant power activate preemption in the traffic control preemption system.
12. The light emitter of claim 11 , wherein the microcontroller is further configured, responsive to the current sense level from one of the groups of LEDs indicating to the microcontroller that the one group of LEDs has failed, to increase the respective current levels, via the at least one trigger switch, to the groups of LEDs other than the failed group of LEDs.
13. The light emitter of claim 11 , further comprising a temperature sensor proximate the groups of LEDs and coupled to the microcontroller, wherein the microcontroller is further configured, responsive to a temperature level from the temperature sensor, to adjust the respective current levels to the groups of LEDs via the at least one trigger switch.
14. The light emitter of claim 11 , wherein the microcontroller is further configured to trigger a subset of the groups of LEDs for each pulse of the pulse pattern, the subset including fewer than all of the groups of LEDs.
15. The light emitter of claim 11 , further comprising:
an IR sensor coupled to the microcontroller, wherein the IR sensor is configured to receive the IR pulse pattern from the groups of LEDs and output a sensed level of IR radiant power of the groups of LEDs; and
wherein the microcontroller is further configured to adjust respective current levels to the groups of LEDs via the at least one trigger switch in response to the sensed level of IR radiant power for maintaining the first level of IR radiant power.
16. The light emitter of claim 11 , wherein the pulse pattern that activates preemption in the traffic control preemption system is a first pulse pattern, and the microcontroller is further configured to trigger a second IR light pulse pattern from the groups of LEDs, and the second pulse pattern is different from the first pulse pattern.
17. The light emitter of claim 11 , wherein the controlled current source is a voltage controlled current source.
18. The light emitter of claim 11 , wherein the microcontroller is further configured to count a number of pulses emitted by each group of LEDs and responsive to the count reaching a threshold, to increase the respective current levels to the groups of LEDs via the at least one trigger switch.
19. A light emitter for a traffic control preemption system, comprising:
a plurality of groups of infrared (IR) LEDs, each group including one or more IR LEDs;
means for providing power to the groups of LEDs;
means for controlling current to the plurality of groups of LEDs; and
programmable means for triggering an IR light pulse pattern from the groups of LEDs and for maintaining a first level of IR radiant power from the groups of LEDs using individual control of respective current levels to the groups of LEDs in response to current sense levels from the groups of LEDs, wherein the pulse pattern and first level of IR radiant power activate preemption in the traffic control preemption system.