System and method for dimming one or more light source

• US 7,592,757 B2
• Filed: 03/29/2007
• Issued: 09/22/2009
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Grupo Antolin-Irausa, S.A.
• Original Assignee: Magna International Incorporated
• Inventors: Hargenrader, John T., Dixon, Mark Edward
• Primary Examiner(s): VO, TUYET THI
• Application Number:
  US11/693,477
• Publication Number:
  US 20080238343A1
• Time in Patent Office: 908 Days
• Field of Search: 315/185.S, 315/200.A, 315312-325, 315291-311, 315274-289, 315/247, 315/246, 315149-159
• US Class Current: 315/324
• CPC Class Codes: H05B 35/00 Electric light sources using a combination of different types of light generation
• CPC Class Codes: H05B 39/047 with pulse width modulation from a DC power source
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A system for dimming one or more light sources includes a first light source that emits a light of a first brightness according to an operating condition of the first light source, a second light source that emits a light of a second brightness according to an operating current of the second light source, wherein the light of the first brightness is different than that of the light of the second brightness, and one or more components that references the operating condition of the first light source, wherein, in response to the referenced operating condition of the first light source, the one or more components modifies the operating current of the second light source to substantially match the light of the second brightness to the light of the first brightness. A method for dimming one or more light sources is also disclosed.

Claims

1. A system for dimming one or more light sources, comprising:

a first light source that emits a light of a first brightness according to an operating condition of the first light source;

a second light source that emits a light of a second brightness according to an operating current of the second light source; and

one or more components that reference the operating condition of the first light source, wherein, in response to the referenced operating condition of the first light source, the one or more components modifies the operating current of the second light source to substantially match the light of the second brightness to the light of the first brightness, wherein the first light source is an incandescent light source and the second light source is a light emitting diode (LED), and wherein the one or more components includes a low pass filter that removes abrupt transitions in the operating current of the second light source.

2. The system for dimming one or more light sources according to claim 1 further comprising a power supply defined by pulse width modulation (PWM) control signal, wherein the modulation of a duty cycle of the PWM control signal controls the light of the first brightness of the first light source.

3. The system for dimming one or more light sources according to claim 1, wherein the one or more components further includes:

a current sense resistor, and

a microprocessor including a look-up table, wherein the look-up table includes a plurality of LED operating current values associated with a plurality of sensed current values of the incandescent light source, wherein the current sense resistor provides a sensed operating current of the incandescent light source to the microprocessor, wherein, in response to the provided operating current of the incandescent light source, the microprocessor selects one of plurality of LED operating current values from the look-up table in view of the provided operating current of the incandescent light source.

4. The system for dimming one or more light sources according to claim 1, wherein the one or more components includes:

an optical sensor that senses the luminance of the incandescent light source; and

a microprocessor including a look-up table, wherein the look-up table includes a plurality of LED operating current values associated with a plurality of sensed luminescent values of the incandescent light source, wherein the optical sensor provides a sensed luminescent value of the incandescent light source to the microprocessor, wherein, in response to the provided luminescent value of the incandescent light source, the microprocessor selects one of plurality of LED operating current values from the look-up table in view of the provided luminescent value of the incandescent light source.

5. The system for dimming one or more light sources according to claim 1, wherein the light of the first brightness from the incandescent light source is not viewable by a vehicle occupant, and wherein light of the second brightness from the LED is viewable by the vehicle occupant.

6. The system for dimming one or more light sources according to claim 1, wherein the one or more components includes:

an optical sensor that senses the luminance of the incandescent light source.

7. The system for dimming one or more light sources according to claim 6, wherein the optical sensor includes:

a transistor that regulates operating current of the LED in view of the sensed luminance of the incandescent light source.

8. A method for dimming one or more light sources, comprising the steps of:

providing light of a first brightness from a first light source according to an operating condition of the first light source;

providing light of a second brightness from a second light source according to an operating current of the second light source;

referencing the operating condition of the first light source;

matching the light of the second brightness to the light of the first brightness; and

passing the operating current of the second light source through a low pass filter to removes abrupt transitions in the operating current of the second light source.

9. The method according to claim 8, wherein prior to providing the light of the first brightness step, the method includes the step of

modulating a power supply defined by a duty cycle of a pulse width modulation (PWM) control signal.

10. The method according to claim 9, wherein the first light source is an incandescent light source and the second light source is a light emitting diode (LED).

11. The method according to claim 10, wherein the operating condition of the incandescent light source is a luminescent output of the incandescent light source.

12. The method according to claim 10 further comprising the step of

preventing the viewability of the light of the first brightness from the incandescent light source is not viewable by a vehicle occupant, and

permitting the viewability of the light of the second brightness from the LED.

13. The method according to claim 10, wherein the operating condition of the incandescent light source is an operating voltage of the incandescent light source.

14. The method according to claim 13, wherein the referencing step further comprises the steps of

associating, in a microprocessor, the operating voltage of the incandescent light source with one of a plurality of operating currents of the LED in a look-up table;

and

selecting one of the plurality of operating currents of the LED in the look-up table that is associated with the operating voltage of the incandescent light source.

15. The method according to claim 13, wherein the referencing step further comprises the steps of

associating, in a microprocessor, the luminescent output of the incandescent light source with one of a plurality of operating currents of the LED in a look-up table;

and

selecting one of the plurality of operating currents of the LED in the look-up table that is associated with the luminescent output of the incandescent light source.

16. A system for dimming one or more light sources, comprising:

a first light source that emits a light of a first brightness according to an operating condition of the first light source;

a second light source that emits a light of a second brightness according to an operating current of the second light source, wherein the light of the first brightness is different than that of the light of the second brightness; and

a means for modifying the operating current of the second light source to substantially math the light of the second brightness to the light of the first brightness, wherein the modifying means includes an optical sensor that senses the luminance of the second light source.

17. The system for dimming one or more light sources according to claim 16, wherein the optical sensor includes:

a transistor that regulates the operating current of the LED in view of the sensed luminance of the incandescent light source.

18. The system for dimming one or more light sources according to claim 16, wherein the means for modifying includes one or more components that references the operating condition of the first light source, wherein, in response to the referenced operating condition of the first light source, the one or more components modifies the operating current of the second light source to substantially match the light of the second brightness to the light of the first brightness.

19. The system for dimming one or more light sources according to claim 18 further comprising a power supply defined by pulse width modulation (PWM) control signal, wherein the modulation of a duty cycle of the PWM control signal controls the light of the first brightness of the first light source.

20. The system for dimming one or more light sources according to claim 19, wherein the first light source is an incandescent light source and the second light source is a light emitting diode (LED).

21. The system for dimming one or more light sources according to claim 20, wherein the one or more components includes:

a low pass filter defined by a resistor, capacitor, and inductor, wherein the low pass filter removes abrupt transitions in the LED operating current.

22. The system for dimming one or more light sources according to claim 20, wherein the one or more components includes:

an current sense resistor; and

a microprocessor including a look-up table, wherein the look-up table includes a plurality of LED operating current values associated with a plurality of sensed current values of the incandescent light source, wherein the current sense resistor provides a sensed operating current of the incandescent light source to the microprocessor, wherein, in response to the provided operating current of the incandescent light source, the microprocessor selects one of plurality of LED operating current values from the look-up table in view of the provided operating current of the incandescent light source.

23. The system for dimming one or more light sources according to claim 20, wherein the one or more components includes:

a microprocessor including a look-up table, wherein the look-up table includes a plurality of LED operating current values associated with a plurality of sensed luminescent values of the incandescent light source, wherein the optical sensor provides a sensed luminescent value of the incandescent light source to the microprocessor, wherein, in response to the provided luminescent value of the incandescent light source, the microprocessor selects one of plurality of LED operating current values from the look-up table in view of the provided luminescent value of the incandescent light source.

24. The system for dimming one or more light sources according to claim 20, wherein the light of the first brightness from the incandescent light source is not viewable by a vehicle occupant and wherein light of the second brightness from the LED is viewable by the vehicle occupant.