Claims
- 1. A method of controlling the brightness of a gas-discharge lamp including a power supply having a drive, the drive supplying a varying signal in response to first and second control signals, the method comprising:
establishing a time period; generating the first and second control signals for the time period including,
for a first interval of the time period, generating the first control signal having a first duty cycle, and generating the second control signal having a second duty cycle; for a second interval of the time period, generating the first control signal having a third duty cycle, the third duty cycle being less than the first duty cycle, and generating the second control signal having a fourth duty cycle, the fourth duty cycle being less than the second duty cycle; and providing the first and second control signals to the drive.
- 2. A method as set forth in claim 1 wherein the first duty cycle is substantially greater than the third duty cycle, and wherein the second duty cycle is substantially greater than the fourth duty cycle.
- 3. A method as set forth in claim 1 wherein the first and second duty cycles are approximately the same, and wherein the third and fourth duty cycles are approximately the same.
- 4. A method as set forth in claim 1 and further comprising:
determining a lamp brightness; and determining a length of the first and second intervals corresponding to the lamp brightness.
- 5. A method as set forth in claim 4 and further comprising:
continuously repeating the generating of the first and second control signals for the determined lamp brightness.
- 6. A method as set forth in claim 1 wherein the generating of the first and second control signals for the time period further includes:
for a third interval of the time period, transitioning the duty cycle of the first control signal, and transitioning the duty cycle of the second control signal.
- 7. A method as set forth in claim 6 wherein the transitioning of the duty cycles of the first and second control signals, respectively, include reducing the duty cycle of the first control signal from the first duty cycle to the third duty cycle and reducing the duty cycle of the second control signal from the second duty cycle to the fourth duty cycle.
- 8. A method as set forth in claim 6 wherein the transitioning of the duty cycles of the first and second control signals, respectively, include increasing the duty cycle of the first control signal from the third duty cycle to the first duty cycle and increasing the duty cycle of the second control signal from the fourth duty cycle to the second duty cycle.
- 9. A method as set forth in claim 1 wherein the generating of the first and second control signals for the time period further includes:
for a third interval of the time period, reducing the duty cycle of the first control signal from the first duty cycle to the third duty cycle and reducing the duty cycle of the second control signal from the second duty cycle to the fourth duty cycle; and for a fourth interval of the time period, increasing the duty cycle of the first control signal from the third duty cycle to the first duty cycle and increasing the duty cycle of the second control signal from the fourth duty cycle to the second duty cycle.
- 10. A method as set forth in claim 9 wherein the reducing and increasing of the duty cycles is performed linearly.
- 11. A method as set forth in claim 4 and further comprising:
determining a second lamp brightness; and determining the first and second intervals corresponding to the second lamp brightness.
- 12. A gas-discharge lamp connectable to a power source and to a gas-discharge tube for controlling a brightness of the tube, the lamp comprising:
a drive that receives direct current (DC) power, receives first and second control signals, and inverts the DC power to create a first varying signal in response to the first and second control signals; a transformer interconnected to the drive that transforms the first varying signal to a second varying signal, the second varying signal being supplied to the tube, a controller interconnected to the drive, the controller generating the first and second control signals for a time period including
for a first interval of the time period, generating the first control signal having a first duty cycle, and generating the second control signal having a second duty cycle, and for a second interval of the time period, generating the first control signal having a third duty cycle, the third duty cycle being less than the first duty cycle, and generating the second control signal having a fourth duty cycle, the fourth duty cycle being less than the second duty cycle.
- 13. A lamp as set forth in claim 12 and further comprising:
a rectifier interconnectable to the power source, the rectifier being operable to receive alternating current (AC) power from the power source and rectifying the AC power to DC power.
- 14. A lamp as set forth in claim 12 wherein the drive includes first and second metal-oxide-semiconductor-field-effect transistors (MOSFET) connected in a half H-bridge configuration.
- 15. A lamp as set forth in claim 12 wherein the controller includes a processor and memory, the memory having one or more software modules executable by the processor.
- 16. A lamp as set forth in claim 12 wherein the first duty cycle is substantially greater than the third duty cycle, and wherein the second duty cycle is substantially greater than the fourth duty cycle.
- 17. A lamp as set forth in claim 12 wherein the first and second duty cycles are approximately the same, and wherein the third and fourth duty cycles are approximately the same.
- 18. A lamp as set forth in claim 12 and further comprising:
an input device operable to receive a desired lamp brightness from an operator; and wherein the controller determines a length of the first and second intervals corresponding to the first lamp brightness.
- 19. A lamp as set forth in claim 12 wherein the controller generates the first and second control signals for the time period including:
for a third interval of the time period, transitioning the duty cycle of the first control signal, and transitioning the duty cycle of the second control signal.
- 20. A lamp as set forth in claim 19 wherein the transitioning of the duty cycles of the first and second control signals, respectively, include reducing the duty cycle of the first control signal from the first duty cycle to the third duty cycle and reducing the duty cycle of the second control signal from the second duty cycle to the fourth duty cycle.
- 21. A lamp as set forth in claim 19 wherein the transitioning of the duty cycles of the first and second control signals, respectively, include increasing the duty cycle of the first control signal from the third duty cycle to the first duty cycle and increasing the duty cycle of the second control signal from the fourth duty cycle to the second duty cycle.
- 22. A lamp as set forth in claim 1 wherein the controller generates the first and second control signals for the time period including:
for a third interval of the time period, reducing the duty cycle of the first control signal from the first duty cycle to the third duty cycle and reducing the duty cycle of the second control signal from the second duty cycle to the fourth duty cycle; and for a fourth interval of the time period, increasing the duty cycle of the first control signal from the third duty cycle to the first duty cycle and increasing the duty cycle of the second control signal from the fourth duty cycle to the second duty cycle.
- 23. A method as set forth in claim 22 wherein the reducing and increasing of the duty cycles is performed linearly.
RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent Application No. 60/208,518, entitled RAMPED DUTY CYCLE DIMMING, filed Jun. 1, 2000.
Provisional Applications (1)
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Number |
Date |
Country |
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60208518 |
Jun 2000 |
US |