초록 ▼

Several driver circuits for energizing series arrays of LEDs are disclosed. The LED driver circuits incorporate programmable microcontrollers and switching regulators in circuits that permit precise control of current applied to the series array of LEDs. One driver circuit senses the condition of a

Several driver circuits for energizing series arrays of LEDs are disclosed. The LED driver circuits incorporate programmable microcontrollers and switching regulators in circuits that permit precise control of current applied to the series array of LEDs. One driver circuit senses the condition of a SYNC line such that the light emission pattern of multiple LED light sources, each with a driver circuit connected to the SYNC line may be coordinated without need for a central controller. Another driver circuit applies an overdrive current to the LEDs for a first pre-determined time period, then ramps down the applied current to a sustainable level. A four channel driver circuit provides each channel with electronic switches arranged to simultaneously turn on and electrically connect a constant current source to an LED array, resulting in abrupt turn on and turn off of the LEDs.

대표청구항 ▼

What is claimed is: 1. A driver circuit for energizing a plurality of LEDs, said driver circuit comprising: a constant current source responsive to a first input to produce a current and connectable to an emitter comprising a plurality of LEDs, said constant current source configured to monitor an

What is claimed is: 1. A driver circuit for energizing a plurality of LEDs, said driver circuit comprising: a constant current source responsive to a first input to produce a current and connectable to an emitter comprising a plurality of LEDs, said constant current source configured to monitor an electrical current through the plurality of LEDs and limit said current to a predetermined value; a controller programmed to; monitor the state of a synchronization input to the controller; provide said first input to said constant current source in a predetermined pattern, initiation of said pattern alternatively controlled by the controller or by a change of state of said synchronization input; and produce a synchronization output indicating initiation of said pattern by said controller; and a synchronization circuit electrically connected to a synchronization line, said synchronization circuit responsive to a change in the electrical potential present on the synchronization line from a first electrical potential to a second electrical potential to provide said synchronization input to the controller and responsive to said synchronization output from the controller to apply said second electrical potential to said synchronization line, wherein initiation of said pattern is triggered by the change of electrical potential on the synchronization line if said synchronization input is present before the controller produces said synchronization output and initiation of said pattern is triggered by the controller if said synchronization input is not present before the controller produces said synchronization output. 2. The driver circuit of claim 1, wherein said pattern comprises: a signal phase; and a resting phase, and wherein said controller is programmed to monitor the state of a phase change input, said phase change input having applied thereto a first potential corresponding to a first state and a second potential corresponding to a second state, and to initiate said pattern with said signal phase or said resting phase until said phase change input changes state and to initiate said pattern with the other of said signal phase or said resting phase after said phase change input changes state, said controller continuing to initiate said pattern with the other of said signal phase or said resting phase until said second potential is again applied to said phase change input. 3. The driver circuit of claim 1, wherein said synchronization circuit comprises a first electronic switch having an off state an on state, a change of state of said first electronic switch providing said synchronization input to said controller and said first electronic switch is electrically connected to said synchronization line such that the state of said first electronic switch is dependent upon the electrical potential present on the synchronization line. 4. The driver circuit of claim 1, wherein said synchronization circuit comprises a second electronic switch having an off state and an on state, said second electronic switch is electrically connected to said synchronization line such that a change of state of the second electronic switch changes the electrical potential present on the synchronization line, the state of said second electronic switch being dependent upon the presence or absence of said synchronization output. 5. The driver circuit of claim 3, wherein said synchronization circuit comprises a second electronic switch having an off state and an on state, said second electronic switch is electrically connected to said synchronization line such that a change of state of the second electronic switch changes the electrical potential present on the synchronization line, the state of said second electronic switch being dependent upon the presence or absence of said synchronization output. 6. The driver circuit of claim 1, comprising an over current detection circuit for detecting current flow from the synchronization line to a ground potential, said over current detection circuit providing an over current input to said controller upon detection of current flow from the synchronization line to a ground potential in excess of a predetermined threshold. 7. A method for coordinating light emission from a plurality of warning light assemblies, each of said warning light assemblies comprising at least one light emitter and a driver circuit for applying a pattern of electrical energy to the at least one light emitter to produce a warning light signal, said method comprising: sensing an electrical potential of a synchronization line to which each of the driver circuits are connected, the synchronization line having applied thereto a first potential corresponding to an absence of a synchronization signal from one of the driver circuits or a second potential corresponding to the presence of a synchronization signal from one of the driver circuits, said sensing performed by a first electrical circuit in each driver circuit; generating a synchronization input to a controller in each said driver circuit corresponding to the presence of said second potential, said synchronization input generated by said first electrical circuit and occurring substantially contemporaneously with a change of the electrical potential of said synchronization line from said first potential to said second potential; generating a synchronization output corresponding to commencement of application of the pattern of electrical energy to the at least one light emitter, said synchronization output generated by the controller in each driver circuit; and applying said second potential to the synchronization line, said applying performed by said first electrical circuit in each driver circuit and triggered by and substantially contemporaneously with the generation of said synchronization output, commencing application of the pattern of electrical energy to the at least one light emitter from the driver circuit of each warning light assembly, said commencing triggered by the generation of said synchronization input if said synchronization input has been generated prior to generation of said synchronization output by the controller of said driver circuit. 8. The method of claim 7, wherein said sensing comprises: connecting an electronic switch in the first electrical circuit to generate said synchronization input coincident with a change of potential on said synchronization line from said first potential to said second potential. 9. The method of claim 7, wherein said applying comprises connecting a second electronic switch in said first electrical circuit to said synchronization line, said second electronic switch responsive to generation of said synchronization output to apply said second potential to the synchronization line. 10. The method of claim 7, comprising: monitoring a current flow from said synchronization line to a ground potential at each driver circuit; and generating an overcurrent input to the controller of a driver circuit where said current flow exceeds a pre-established value. 11. A driver circuit for energizing a plurality of LEDs, each said LED having a maximum safe average current IAvg., and a peak pulsed forward current IP, said driver circuit comprising: a constant current source responsive to the presence of a first input to provide an overdrive current IOD through said plurality of LEDs, said overdrive current IOD being greater than said maximum safe average current IAvg and less than or approximately equal to said peak pulsed forward current IP; and a controller programmed to provide said first input to said constant current source at a 100% duty cycle for a first pre-determined time period, said controller programmed to modulate the duty cycle of said first input such that the average current applied to the LEDs is reduced from said overdrive current IOD to approximately said maximum safe average current IAvg. 12. The driver circuit of claim 11, wherein the current applied to the LEDs is reduced gradually over a second pre-determined time period. 13. The driver circuit of claim 12, wherein said first pre-determined time period is approximately 1 second and said second predetermined time period is approximately 7 seconds. 14. The driver circuit of claim 11, wherein said overdrive current IOD is approximately 1.1 to 1.3 times greater than said maximum safe average current IAvg. 15. The driver circuit of claim 11, wherein said overdrive current IOD is approximately 90 to 100 percent of said peak pulsed current IP. 16. A method of energizing an LED to produce a warning light pattern, said LED having a maximum safe average current IAvg. and a peak pulsed current IP, said method comprising: applying an overdrive current IOD to said LED for a first pre-determined time period of each energization of the LED, said overdrive current IOD being greater than said maximum safe average current IAvg and less than or equal to said peak pulsed current IP; and reducing the current applied to said LED from said overdrive current IOD to said maximum safe average current IAvg. if said energization of the LED has a duration in excess of said first pre-determined time period. 17. The method of claim 16, wherein said step of reducing comprises: gradually reducing the current applied to said LED from said overdrive current IOD over a second pre-determined time period. 18. The method of claim 17, wherein said first pre-determined time period is approximately 1 second and said second pre-determined time period is approximately 7 seconds. 19. The method of claim 16, wherein said reducing comprises reducing a duty cycle of an on/off input to a constant current source configured to apply a constant current equal to IOD to said LED if provided with an on/off input having a 100% duty cycle. 20. A driver circuit for energizing a light emitter, said driver circuit comprising: an energizing circuit responsive to a first input to energize the light emitter; a controller connected and programmed to; monitor the state of a synchronization input to the controller; provide said first input to said energizing circuit in a predetermined pattern, initiation of said pattern alternatively controlled by the controller or by a change of state of said synchronization input; and produce a synchronization output indicating initiation of said pattern by said controller; and a synchronization circuit electrically connected to a synchronization line, said synchronization circuit responsive to a change in the electrical potential present on the synchronization line from a first electrical potential to a second electrical potential to provide said synchronization input to the controller and responsive to said synchronization output from the controller to apply said second electrical potential to said synchronization line, wherein initiation of said pattern is triggered by the change of electrical potential on the synchronization line if said synchronization input is present before the controller produces said synchronization output and initiation of said pattern is triggered by the controller if said synchronization input is not present before the controller produces said synchronization output. 21. The driver circuit of claim 20, wherein said synchronization circuit comprises a first electronic switch having an off state an on state, a change of state of said first electronic switch providing said synchronization input to said controller and said first electronic switch is electrically connected to said synchronization line such that the state of said first electronic switch is dependent upon the electrical potential present on the synchronization line. 22. The driver circuit of claim 20, wherein said synchronization circuit comprises a second electronic switch having an off state and an on state, said second electronic switch is electrically connected to said synchronization line such that a change of state of the second electronic switch changes the electrical potential present on the synchronization line, the state of said second electronic switch being dependent upon the presence or absence of said synchronization output. 23. The driver circuit of claim 22, wherein said synchronization circuit comprises a second electronic switch having an off state and an on state, said second electronic switch is electrically connected to said synchronization line such that a change of state of the second electronic switch changes the electrical potential present on the synchronization line, the state of said second electronic switch being dependent upon the presence or absence of said synchronization output. 24. The driver circuit of claim 20, comprising an over current detection circuit for detecting current flow from the synchronization line to a ground potential, said over current detection circuit providing an over current input to said controller upon detection of current flow from the synchronization line to a ground potential in excess of a predetermined threshold.