APPARATUS AND METHODS FOR DIMMING ILLUMINATION DEVICES
First Claim
1. A method of dimming a plurality of LEDs, comprising:
- generating a first pulse-width modulated (PWM) waveform;
the first PWM waveform having a first duty cyclegenerating a plurality of second PWM waveforms;
each of the plurality of second PWM waveforms having a duty cycle;
starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at approximately the same time;
ending the periods of each of the second PWM waveforms before the end of the first PWM iteration;
closing and opening a first switch in response to the duty cycle of the first PWM waveform;
closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs;
where each second switch is closed in response to the respective duty cycles of each second PWM waveform;
so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open.
1 Assignment
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Accused Products
Abstract
A method of dimming a plurality of LEDs includes generating a first pulse-width modulated (PWM) waveform and generating a plurality of second PWM waveforms, each of the PWM waveforms having a duty cycle. The duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms begin at approximately the same time. The periods of each of the second PWM waveforms end before the end of the first PWM duty cycle. In the method, and in disclosed circuits and devices, a first switch is closed in response to the duty cycle of the first PWM waveform, and each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs is closed in response to the respective duty cycles of each second PWM waveform, so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open. In this way, the chromaticity of each LED is not affected by the length of the duty cycle of the dimming PWM.
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Citations
37 Claims
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1. A method of dimming a plurality of LEDs, comprising:
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generating a first pulse-width modulated (PWM) waveform; the first PWM waveform having a first duty cycle generating a plurality of second PWM waveforms; each of the plurality of second PWM waveforms having a duty cycle; starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at approximately the same time; ending the periods of each of the second PWM waveforms before the end of the first PWM iteration; closing and opening a first switch in response to the duty cycle of the first PWM waveform; closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs;
where each second switch is closed in response to the respective duty cycles of each second PWM waveform;so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (2, 3)
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4. A circuit for dimming a plurality of LEDs, the circuit comprising:
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a first PWM circuit; the first PWM circuit having a first duty cycle a plurality of second PWM circuits; the plurality of second PWM circuits each having a duty cycle; the duty cycle of each of the second PWM circuits configured to start at substantially the same time as the start of the duty cycle of the first PWM circuit; the period of each of the second PWM circuits configured to end at or before the end of the iteration of the first PWM circuit; a first switch responsive to the duty cycle of the first PWM circuit; a plurality of second switches, each of the second switches responsive to the duty cycle of one of the plurality of second PWM circuits; each of the second switches capable of being connected to a LED; so that each LED so connected between each of the second switches and a power source is energized when the first switch and the corresponding second switch are closed, and is not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (5, 6, 7, 8)
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9. A circuit for dimming a plurality of LEDs, the circuit comprising:
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a means for generating a first PWM waveform; the first PWM waveform having a first duty cycle means for generating a plurality of second PWM waveforms; the plurality of second PWM waveforms each having a duty cycle; means for starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at substantially the same time; means for ending the duty cycles of each of the second PWM waveforms before the end of the first PWM duty cycle; means for closing and opening a first switch in response to the duty cycle of the first PWM waveform; means for closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs; where each second switch is closed in response to the respective duty cycles of each second PWM waveform; so that each LED connected between each of the second switches and a power source is energized when the first switch and the corresponding second switch are closed, and is not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (10, 11, 12, 13)
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14. A computer-readable medium having computer-executable instructions for performing a method;
- the method comprising;
generating a first PWM waveform; the first PWM waveform having a first duty cycle generating a plurality of second PWM waveforms; each of the plurality of second PWM waveforms having a duty cycle; starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at substantially the same time; ending the periods of each of the second PWM waveforms before the end of the first PWM iteration; causing the closing and opening a first switch in response to the duty cycle of the first PWM waveform; causing the closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs; where each second switch is closed in response to the respective duty cycles of each second PWM waveform; so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (15, 16)
- the method comprising;
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17. A dimmable illumination device, comprising:
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a first LED, a second LED, and a third LED, each of the first, second and third LEDs emitting light at a different wavelength than either of the other LEDs; three color PWM waveform sources, selectable to drive the first, second and third LEDs independent of one another; an intensity PWM waveform source, coupled to the first, second, and third LED'"'"'s to drive the first, second, and third LEDs in combination; where the iteration of the intensity PWM waveform source is an integral multiple of each of the periods of the three color PWM waveform sources. - View Dependent Claims (18, 19, 20)
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21. An instrument panel, the instrument panel comprising:
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a plurality of LEDs; a circuit for dimming the plurality of LEDs, the circuit comprising; a first PWM circuit; the first PWM circuit having a first duty cycle a plurality of second PWM circuits; the plurality of second PWM circuits each having a duty cycle; the duty cycle of each of the second PWM circuits configured to start at substantially the same time as the start of the duty cycle of the first PWM circuit; the period of each of the second PWM circuits configured to end at or before the end of the iteration of the first PWM circuit; a first switch responsive to the duty cycle of the first PWM circuit; a plurality of second switches, each of the second switches responsive to the duty cycle of one of the plurality of second PWM circuits; each of the second switches capable of being connected to a LED; so that each LED so connected between each of the second switches and a power source is energized when the first switch and the corresponding second switch are closed, and is not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (22, 23, 24, 25)
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26. An instrument panel, the instrument panel comprising:
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a plurality of LED'"'"'s; a computer-readable medium having computer-executable instructions for performing a method;
the method comprising;generating a first PWM waveform; the first PWM waveform having a first duty cycle generating a plurality of second PWM waveforms; each of the plurality of second PWM waveforms having a duty cycle; starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at substantially the same time; ending the periods of each of the second PWM waveforms before the end of the first PWM iteration; causing the closing and opening a first switch in response to the duty cycle of the first PWM waveform; causing the closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs;
where each second switch is closed in response to the respective duty cycles of each second PWM waveform;so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (27, 28)
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29. An area lighting system, the area lighting system comprising:
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a plurality of LEDs; a circuit for dimming the plurality of LEDs, the circuit comprising; a first PWM circuit; the first PWM circuit having a first duty cycle a plurality of second PWM circuits; the plurality of second PWM circuits each having a duty cycle; the duty cycle of each of the second PWM circuits configured to start at substantially the same time as the start of the duty cycle of the first PWM circuit; the period of each of the second PWM circuits configured to end at or before the end of the iteration of the first PWM circuit; a first switch responsive to the duty cycle of the first PWM circuit; a plurality of second switches, each of the second switches responsive to the duty cycle of one of the plurality of second PWM circuits; each of the second switches capable of being connected to a LED; so that each LED so connected between each of the second switches and a power source is energized when the first switch and the corresponding second switch are closed, and is not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (30, 31, 32, 34)
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35. An area lighting system, the area lighting system comprising:
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a plurality of LED'"'"'s; a computer-readable medium having computer-executable instructions for performing a method;
the method comprising;generating a first PWM waveform; the first PWM waveform having a first duty cycle generating a plurality of second PWM waveforms; each of the plurality of second PWM waveforms having a duty cycle; starting the duty cycle of the first PWM waveform and the duty cycle of each of the second PWM waveforms at substantially the same time; ending the periods of each of the second PWM waveforms before the end of the first PWM iteration; causing the closing and opening a first switch in response to the duty cycle of the first PWM waveform; causing the closing and opening each of a plurality of second switches connected between the first switch and a corresponding plurality of LEDs;
where each second switch is closed in response to the respective duty cycles of each second PWM waveform;so that each LED connected between each second switch and a power source is energized when the first switch and the corresponding second switch are closed and not energized when either the first switch or the corresponding second switch is open. - View Dependent Claims (36, 37)
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Specification