Color-adjusted camera light and method

• US 6,488,390 B1
• Filed: 10/16/2001
• Issued: 12/03/2002
• Est. Priority Date: 03/19/1998
• Status: Expired due to Term

• Current Assignee: Lemaire Illumination Technologies LLC
• Original Assignee: PPT Vision, Inc. (Datalogic S.p.A.)
• Inventors: Lebens, Gary A., Bourn, Charles T., Lemaire, Charles A.
• Primary Examiner(s): Husar, Stephen
• Assistant Examiner(s): Zeade, Bertrand
• Application Number:
  US09/978,760
• Time in Patent Office: 413 Days
• Field of Search: 362/157, 362/183, 362/159, 362/184, 362/208, 362/800, 362/249, 362/11, 362/13, 362/234, 315/224, 315/307, 315/291, 315/312, 315/360, 315/362
• US Class Current: 362/231
• CPC Class Codes: F21L 4/027 the light sources being a LED
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H04B 10/502 LED transmitters
• CPC Class Codes: H04B 10/564 Power control
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/32 Pulse-control circuits
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10S 362/802 Position or condition responsive switch

Abstract

Improved method and apparatus for hand-held portable illumination. A flashlight and corresponding method are described. The flashlight includes a housing, a plurality of LEDs, and an electrical circuit that selectively applies power from the DC voltage source to the LED units, wherein the flashlight is suitable for handheld portable operation by a user. In one embodiment, the first electrical circuit further includes a control circuit for maintaining a predetermined light output level of the LED units as a charge on a battery varies. In another embodiment, the control circuit maintains an average predetermined light output level of the LED units as the charge on the battery cell varies by changing a pulse width or frequency as the charge on the battery cell varies to maintain a given average light output. Another aspect provides an illumination source that includes a light-emitting diode (LED) housing including one or more LEDs, and a control circuit that selectively applies power from a source of electric power to the LEDs, the control circuit substantially maintaining a light output characteristic of the LEDs as a voltage of the voltage source varies over a range that would otherwise vary the light output characteristic. Still another aspect provides an illumination source including a light-emitting diode (LED) housing including one or more LEDs; and a control circuit that selectively applies power from a source of electric power to the LEDs, thus maintaining or controlling a light output color spectrum of the LEDs.

Claims

1. A portable video camera and illumination source system, comprising:

a housing;

one or more light-emitting diodes (LEDs) attached to the housing;

a video camera imaging device attached to the housing;

a control circuit that selectively applies a plurality of pulses from a source of electric power to the one or more LEDs; and

a feedback signal coupled to the control circuit, wherein the control circuit changes a characteristic of each one of the plurality of pulses to control a light output characteristic of the LEDs based on the feedback signal.

2. The system of claim 1, wherein the feedback signal is based, at least in part, on an amount of overall ambient light.

3. The system of claim 1, wherein the feedback signal changes to compensate for a change of a voltage of the source of electric power.

4. The system of claim 1, wherein the feedback signal is based on battery voltage, and the control circuit increases pulse width as battery voltage declines.

5. The system of claim 1, wherein the feedback signal is based on battery voltage, and the control circuit increases pulse frequency as battery voltage declines.

6. The system of claim 1, wherein the control circuit synchronizes pulses to a light-collection period of the imaging device in order that the light pulses from the LEDs are only on when the imaging device is collecting light.

7. The system of claim 1, wherein the feedback signal is based on a video output signal from the imaging device and the control circuit adjusts the light output characteristic in order to improve the video signal.

8. The system of claim 1, wherein the feedback signal is based on a color balance of a output signal from the imaging device and the control circuit separately adjusts the light output characteristic of each of a plurality of different color LEDs.

9. The system of claim 1, wherein the control circuit adjusts a height of a pulse to control a color spectrum of the output light and adjusts a width of the pulse frequency to control an amount of the output light.

10. The system of claim 1, wherein the control circuit adjusts a height of a pulse to control a color spectrum of the output light and adjusts a pulse frequency to control an amount of the output light.

12. The method of claim 1, wherein the feedback is based, at least in part, on an amount of overall ambient light.

13. The method of claim 1, wherein the feedback changes to compensate for a change of a voltage of the source of electric power.

14. The method of claim 1, wherein the feedback is based on battery voltage, and the control circuit increases pulse width as battery voltage declines.

15. The method of claim 1, wherein the feedback is based on battery voltage, and the control circuit increases pulse frequency as battery voltage declines.

16. The method of claim 1, wherein the controlling synchronizes the pulses to a light-collection period of the obtaining the video image.

17. The method of claim 1, wherein the feedback is based on a video image and the controlling adjusts the light output characteristic in order to improve the video image.

18. The method of claim 1, wherein the feedback is based on a color balance of the video image and the controlling separately adjusts the light output characteristic of each of a plurality of different color LEDs.

11. A method for illuminating a scene and obtaining a video image comprising:

controlling one or more light output pulses, directed towards the scene, of one or more light-emitting diodes (LEDs);

obtaining a video image of the scene; and

generating feedback, wherein the controlling changes a characteristic of the light output pulses of the LEDs based on the feedback.

19. An illumination source comprising:

a housing;

one or more light-emitting diodes (LEDs) attached to the housing;

a control circuit operatively coupled to supply electrical pulses to the one or more LEDs that adjusts a height of the pulses to control a color spectrum of the LED output light and adjusts an LED on-time proportion to control an amount of the output light.

20. The illumination source of claim 19, further comprising:

a video camera imaging device attached to the housing;

wherein the control circuit adjusts pulse width in order to control the LED on-time proportion.

21. The illumination source of claim 19, further comprising:

a video camera imaging device attached to the housing, wherein the control circuit adjusts a pulse frequency in order to control the LED on-time proportion.

22. The illumination source of claim 19, wherein the control circuit adjusts a pulse width in order to control the LED on-time proportion.

23. The illumination source of claim 19, wherein the control circuit adjusts a pulse frequency in order to control the LED on-time proportion.

24. An illumination source comprising:

a housing;

one or more light-emitting diodes (LEDs) attached to the housing;

a control circuit operatively coupled to supply electrical pulses to the one or more LEDs that, corresponding to a change in a height of the pulses to the one or more LEDs, adjusts an LED on-time proportion to control an amount of output light.

25. The illumination source of claim 24, wherein the control circuit adjusts a pulse width to control the LED on-time proportion, in order to maintain a substantially constant average light output.

26. The illumination source of claim 24, wherein the control circuit adjusts a pulse frequency to control the LED on-time proportion, in order to maintain a substantially constant average light output.

27. The illumination source of claim 24, further comprising:

a video camera imaging device attached to the housing, wherein the control circuit adjusts a pulse width in order to control the LED on-time proportion.

28. The illumination source of claim 24, further comprising:

a video camera imaging device attached to the housing, wherein the control circuit adjusts a pulse frequency in order to control the LED on-time proportion.

29. An illumination source system, comprising:

a housing;

one or more light-emitting diodes (LEDs) attached to the housing; and

a control circuit that selectively applies a plurality of pulses from a source of electric power to the one or more LEDs;

wherein the control circuit has a feedback signal input, wherein the control circuit changes a characteristic of each one of the plurality of pulses to control a light output characteristic of the LEDs based on the feedback signal.

30. The system of claim 29, wherein the feedback signal is based, at least in part, on an amount of overall ambient light.

31. The system of claim 29, wherein the feedback signal changes to compensate for a change of a voltage of the source of electric power.

32. The system of claim 29, wherein the feedback signal is based on battery voltage, and the control circuit increases a pulse width as a voltage of the source of electric power declines.

33. The system of claim 29, wherein the feedback signal is based on battery voltage, and the control circuit increases a pulse frequency as a voltage of the source of electric power declines.

34. The system of claim 29, further comprising a video camera imaging device, wherein the control circuit synchronizes pulses to a light-collection period of the imaging device in order that the light pulses from the LEDs are only on when the imaging device is collecting light.

35. A method for illuminating a scene comprising:

controlling one or more light output pulses, directed towards the scene, of one or more light-emitting diodes (LEDs);

obtaining a video image of the scene; and

generating feedback, wherein the controlling maintains a characteristic of the illumination on the scene by varying the pulses of the LEDs based on the feedback.

36. The method of claim 35, wherein the feedback is based, at least in part, on an amount of overall ambient light.

37. The method of claim 35, wherein the feedback changes to compensate for a change of a voltage of the source of electric power.

38. The method of claim 35, wherein the feedback is based on battery voltage, and the control circuit increases pulse width as battery voltage declines.

39. The method of claim 35, wherein the feedback is based on battery voltage, and the control circuit increases pulse frequency as battery voltage declines.

40. The method of claim 35, wherein the feedback is based at least in part on a measurement of color.