Pulsed current averaging controller with amplitude modulation and time division multiplexing for arrays of independent pluralities of light emitting diodes
First Claim
1. A method for regulating current in an electrical load, the current provided to the electrical load via a switch and an inductor, the method comprising:
- providing current to the inductor for a first predetermined period of time;
following the first predetermined period of time, providing current to the electrical load and determining an average current provided to the electrical load during a second predetermined period of time;
comparing the average current to a predetermined reference level;
when the average current is less than the predetermined reference level, increasing the first predetermined period of time for a next cycle by at least one first predetermined time increment; and
when the average current is greater than the predetermined reference level during the second predetermined period of time, determining a third period of time which elapses until the average current becomes less than the predetermined reference level, determining an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and decreasing the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment.
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Accused Products
Abstract
Exemplary embodiments provide a system, method and appartus for regulating current in loads, such as in an array of independent pluralities of light emitting diodes (“LEDs”). An exemplary system comprises a multiplexer adapted to switch current to each independent string of LEDs; a first controller to maintain a substantially constant average current level to the plurality of LEDs; and a second controller to modulate a current amplitude and duration of time division multiplexing for each independent string of LEDs. Another aspect of the system provides for modulating the on time for switching current to maintain a substantially constant average current level and to respond and converge quickly to changing current reference levels.
270 Citations
59 Claims
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1. A method for regulating current in an electrical load, the current provided to the electrical load via a switch and an inductor, the method comprising:
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providing current to the inductor for a first predetermined period of time;
following the first predetermined period of time, providing current to the electrical load and determining an average current provided to the electrical load during a second predetermined period of time;
comparing the average current to a predetermined reference level;
when the average current is less than the predetermined reference level, increasing the first predetermined period of time for a next cycle by at least one first predetermined time increment; and
when the average current is greater than the predetermined reference level during the second predetermined period of time, determining a third period of time which elapses until the average current becomes less than the predetermined reference level, determining an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and decreasing the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for regulating current in an electrical load, the system comprising:
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a converter couplable to the electrical load, the converter comprising a switch and an inductor to provide current to the electrical load; and
a first controller coupled to the converter, the first controller adapted to control the switch to provide current to the inductor for a first predetermined period of time and to provide current to the electrical load for a second predetermined period of time;
to determine an average current provided to the electrical load during the second predetermined period of time;
to compare the average current to a predetermined reference level;
the first controller further adapted, when the average current is less than the predetermined reference level, to increase the first predetermined period of time for a next cycle by at least one first predetermined time increment, and when the average current is greater than the predetermined reference level during the second predetermined period of time, to determine a third period of time which elapses until the average current becomes less than the predetermined reference level, to determine an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and to decrease the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 28, 29, 30)
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- 24. The system of claim 24, wherein the second controller is further adapted to determine the duration of the time division multiplexing of a current pulse for each independent plurality of light emitting diodes of the array as a product of its corresponding average DC current and cycle time divided by a value of the current corresponding to the predetermined reference level.
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31. An apparatus for regulating current in an electrical load, the apparatus couplable to a converter to provide current to the electrical load through a switch and an inductor, the apparatus comprising:
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digital logic adapted to control the switch to provide current to the inductor for a first predetermined period of time and to provide current to the electrical load for a second predetermined period of time;
an integrator to determine an average current during the second predetermined period of time; and
a comparator coupled to the integrator and to the digital logic, the comparator adapted to compare the average current to a predetermined reference level;
wherein the digital logic is further adapted, when the average current is less than the predetermined reference level, to increase the first predetermined period of time for a next cycle by at least one first predetermined time increment, and when the average current is greater than the predetermined reference level during the second predetermined period of time, to determine a third period of time which elapses until the average current becomes less than the predetermined reference level, to determine an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and to decrease the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A method of regulating current in an array of independent pluralities of light emitting diodes of corresponding colors, the method comprising:
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modulating a current amplitude duration of time division multiplexing for each independent plurality of light emitting diodes of the array; and
maintaining a substantially constant average current level to the plurality of light emitting diodes of the array. - View Dependent Claims (45, 46, 47, 48, 49, 50)
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51. A system for regulating current in an array of independent pluralities of light emitting diodes of corresponding colors, the system comprising:
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a multiplexer adapted to switch current to each independent plurality of light emitting diodes of the array;
a first controller adapted to maintain a substantially constant average current level to the plurality of light emitting diodes of the array; and
a second controller coupled to the multiplexer and to the first controller, the array controller adapted to modulate a current amplitude and duration of time division multiplexing of current for each independent plurality of light emitting diodes of the array. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59)
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Specification