Burst pulse circuit for signal lights and method

• US 20050012636A1
• Filed: 06/15/2004
• Published: 01/20/2005
• Est. Priority Date: 07/10/2003
• Status: Active Grant

• Current Assignee: Tracon Industries Corporation
• Original Assignee: Tracon Industries Corporation
• Inventors: Johnson, Matthew, Gallagher, Shawn, Zink, Timothy
• Granted Patent: US 7,372,441 B2
• Time in Patent Office: Days
• US Class Current: 340/815.450
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/327 Burst dimming

Abstract

A circuit is provided for over-driving a super-luminescent light emitting diode having a maximum forward continuous current rating. A power supply provides a pulse width modulated signal to an analog memory connected to the power supply and a pulse generator. The pulse generator includes a window comparator engaged with the analog memory, and is responsive to a portion of the pulse width modulated signal. A power driver that is controlled by the output of the pulse generator, is operably connected with the super-luminescent light emitting diode and with the power supply so as to energize the super-luminescent light emitting diode with a current that is above the maximum forward continuous current rating by between two and ten times that rated current. A signal is also provided along with a method of over-driving a super-luminescent light emitting diode. An inverter and timer are coupled to the pulse generator and an array of light emitting diodes that operate at time intervals determined by the timer that are wholly distinct from time intervals when the at least one super-luminescent light emitting diode is over-driven.

Claims

1. A circuit for over-driving a light emitting diode comprising:

at least one white super-luminescent light emitting diode having a maximum forward continuous current rating;

a power supply that provides a pulse width modulated signal;

an analog memory connected to said power supply;

a pulse generator comprising a window comparator engaged with said analog memory and responsive to a portion of said pulse width modulated signal

an array of amber light emitting diodes controllably connected to said pulse generator through an inverter and a timer; and

at least one power driver controlled by the output of said pulse generator and operably connected with said at least one white super-luminescent light emitting diode, said array of amber light emitting diodes and with said power supply so as to over-drive said at least one white super-luminescent light emitting diode with a current having a magnitude above said maximum forward continuous current rating, and said array of amber light emitting diodes are illuminated at time intervals determined by said timer that are wholly distinct from time intervals when said at least one white super-luminescent light emitting diode is over-driven.

2. A circuit according to claim 1 wherein said magnitude is between two and ten times said maximum forward continuous current rating of said at least one super-luminescent light emitting diode.

3. A circuit according to claim 1 wherein said analog memory comprises means for storing a portion of said pulse width modulated signal.

4. A circuit according to claim 1 wherein said analog memory comprises a diode and a capacitor.

5. A circuit according to claim 1 wherein said pulse generator comprises means for generating a pulse.

6. A circuit according to claim 1 wherein said pulse generator includes a one-shot timer having a trigger pin electrically connected to a threshold pin.

7. A circuit according to claim 6 wherein a resistor is electrically connected between said analog memory said trigger pin.

8. A circuit according to claim 7 wherein said a capacitor is electrically connected between said trigger pin, said threshold pin, and a reference level.

9. A circuit according to claim 8 wherein the values of said resistor and said capacitor determine an “

off-on”

time interval for output pulses from said pulse generator.

10. A circuit according to claim 8 wherein said trigger pin and said threshold pin are held high relative to a reference by a capacitor after initial charging of said capacitor.

11. A circuit according to claim 8 wherein said power driver comprises a field effect transistor.

12. A circuit according to claim 8 wherein said power driver “

over-drives”

said at least one super-luminescent light emitting diode for a period of time less than the pulse frequency of said pulse width modulated signal.

13. A circuit according to claim 1 wherein said super-luminescent light emitting diode comprises an absolute maximum forward continuous current rating, at twenty-five °

C., of thirty milliamperes, and a pulse forward current rating of seventy milliamperes.

14. A circuit according to claim 1 wherein said super-luminescent light emitting diode comprises an absolute maximum forward continuous current rating, at twenty-five °

C., of twenty milliamperes.

15. A circuit according to claim 1 wherein said array of amber light-emitting diodes are driven by driver means operably engaged with said power supply, and said inverter is responsive to said portion of said pulse width modulated signal and operatively engaged with said timer so as to suppress operation of said driver means for a period of time less than the pulse frequency of said pulse width modulated signal thereby to delay by a predetermined and adjustable amount of time the illumination cycle of said array of amber light-emitting diodes so as to allow for a complete “

off-on”

cycle of said at least one white super-luminescent light emitting diode.

16. A circuit for over-driving a light emitting diode comprising:

at least one super-luminescent light emitting diode having a maximum forward continuous current rating;

a power supply that provides a pulse width modulated signal;

an analog memory connected to said power supply;

a window comparator engaged with said analog memory and responsive to a portion of said pulse width modulated signal;

an array of amber light emitting diodes controllably connected to said window comparator through an inverter and a timer; and

a power driver controlled by the output of said window comparator and operably connected with said at least one super-luminescent light emitting diode and with said power supply such that when said pulse width modulated signal encounters said analog memory circuit, said window comparator is caused to trigger said power driver to “

over-drive”

said at least one super-luminescent light emitting diode for approximately twenty-five to thirty milliseconds so as to create a super-bright pulse of light to be emitted;

wherein said array of amber light-emitting diodes are driven by driver means operably engaged with said power supply, and said inverter is responsive to said portion of said pulse width modulated signal and operatively engaged with said timer so as to suppress operation of said driver means for a period of time less than the pulse frequency of said pulse width modulated signal thereby to delay by a predetermined and adjustable amount of time the illumination cycle of said array of amber light-emitting diodes so as to allow for a complete “

off-on”

cycle of said at least one white super-luminescent light emitting diode.

17. A circuit for over-driving a light emitting diode comprising:

at least one super-luminescent light emitting diode having a maximum forward continuous current rating;

a power supply that provides a pulse width modulated signal;

an analog memory connected to said power supply;

a pulse generator engaged with said analog memory and responsive to a portion of said pulse width modulated signal;

at least one light emitting diode controllably connected to said window comparator through an inverter and a timer; and

a power driver controlled by the output of said pulse generator and operably connected with said at least one super-luminescent light emitting diode, said at least one light emitting diode, and with said power supply so as to over-drive said at least one super-luminescent light emitting diode with a current that is at least two times said maximum forward continuous current rating, and said at least one light emitting diode being illuminated at time intervals determined by said timer that are wholly distinct from time intervals when said at least one super-luminescent light emitting diode is over-driven.

18. A signal comprising:

a power supply that provides a pulse width modulated signal;

an array of flashing lights arranged in electrical communication with an inverter and a timer and each light comprising a plurality of light emitting diodes having a first color and a first brightness wherein each of said flashing lights also includes at least one super-luminescent light emitting diode having a maximum forward continuous current rating, a second color, and a second brightness;

an analog memory connected to said power supply and responsive to a portion of said pulse width signal;

a pulse generator comprising a window comparator responsive to said analog memory and a portion of said pulse width modulated signal; and

a power driver controlled by the output of said pulse generator and operably connected with said at least one super-luminescent light emitting diode and with said power supply so as to over-drive said at least one super-luminescent light emitting diode with at least five times said maximum forward continuous current rating, and said plurality of light emitting diodes having said first color and said first brightness being illuminated at time intervals determined by said timer that are wholly distinct from time intervals when each of said at least one super-luminescent light emitting diode is over-driven.

19. A signal according to claim 18, wherein said second brightness is at least two times the magnitude of said first brightness.

20. A signal according to claim 18, wherein said over-driven super-luminescent light emitting diode yields between four thousand and ten thousand millicandellas of illumination.

21. A signal according to claim 18 wherein said magnitude is between two and ten times said maximum forward continuous current rating of said at least one super-luminescent light emitting diode.

22. A signal according to claim 18 wherein said analog memory comprises means for storing a portion of said pulse width modulated signal.

23. A signal according to claim 18 wherein said analog memory comprises a diode and a capacitor.

24. A signal according to claim 18 wherein said pulse generator comprises means for generating a pulse.

25. A signal according to claim 18 wherein said pulse generator includes a one-shot timer having a trigger pin electrically connected to a threshold pin.

26. A signal according to claim 25 wherein a resistor is electrically connected between said analog memory said trigger pin.

27. A signal according to claim 26 wherein said a capacitor is electrically connected between said trigger pin, said threshold pin, and a reference level.

28. A signal according to claim 26 wherein the values of said resistor and said capacitor determine an “

off-on”

time interval for output pulses from said pulse generator.

29. A signal according to claim 26 wherein said trigger pin and said threshold pin are held high relative to a reference by a capacitor after initial charging of said capacitor.

30. A signal according to claim 27 wherein said power driver comprises a field effect transistor.

31. A signal according to claim 28 wherein said power driver “

over-drives”

said at least one superluminescent light emitting diode for a period of time less than the pulse frequency of said pulse width modulated signal.

32. A signal according to claim 28 wherein said super-luminescent light emitting diode comprises an absolute maximum forward continuous current rating, at twenty-five °

C., of thirty milliamperes, and a pulse forward current rating of seventy milliamperes.

33. A signal according to claim 18 wherein said super-luminescent light emitting diode comprises an absolute maximum forward continuous current rating, at twenty-five °

C., of twenty milliamperes.

34. A signal according to claim 18 including means for driving said array of flashing lights wherein said inverter is responsive to said portion of said pulse width modulated signal and cooperates with said timer so as to suppress operation of said means for driving for periods of time less than the pulse frequency of said pulse width modulated signal.

35. A method for creating a bright strobed light comprising over-driving at least one super-luminescent light emitting diode having a maximum forward continuous current rating, into forward biased conduction with a current of at least five times said maximum forward continuous current rating;

and

delaying operation of an array of light emitting diodes associated with said at least one super-luminescent light emitting diode such that time intervals determined by said timer are wholly distinct from time intervals when said at least one super-luminescent light emitting diode is over-driven.

36. The method of claim 35 comprising:

providing;

(a) a circuit for over-driving said at least one super-luminescent light emitting diode;

(b) a power supply that provides a pulse width modulated signal;

(c) an analog memory connected to said power supply;

(d) a pulse generator comprising a window comparator engaged with said analog memory and responsive to a portion of said pulse width modulated signal; and

(e) a power driver controlled by the output of said pulse generator and operably connected with said at least one super-luminescent light emitting diode and with said power supply so as to energize said at least one super-luminescent light emitting diode with a current having a magnitude above said maximum forward continuous current rating; and

applying a pulse width modulated signal from said from said power supply to said circuit.

37. The method of claim 36 comprising:

widening the width of the pulses forming said pulse width modulated signal thereby dimming said at least one super-luminescent light emitting diode in proportion said change in width.

38. The method of claim 35 comprising over-driving a plurality of super-luminescent light emitting diodes.

39. The method of claim 35 comprising at least one of diffusing and focusing light emitted by said plurality of super-luminescent light emitting diodes.

40. The method of claim 35 comprising driving an array of flashing lights and inverting a portion of said pulse width modulated signal so as to suppress operation of said array of flashing lights for a period of time less than the pulse frequency of said pulse width modulated signal.