Capacitive ladder feed for AC LED
First Claim
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1. A circuit serving as a light source, the circuit comprising:
- a first set of light-emitting diodes (LEDs); and
a second set of LEDs that is connected in series to the first set of LEDs,wherein the first set of LEDs comprises;
a first group of LEDs;
a second group of LEDs connected in anti-parallel with the first group of LEDs, wherein each of the first group of LEDs and the second group of LEDs comprises at least one LED; and
a first capacitor connected in parallel with the first group of LEDs and the second group of LEDs, andwherein the second set of LEDs comprises;
a third group of LEDs;
a fourth group of LEDs connected in anti-parallel with the third group of LEDs, wherein each of the third group of LEDs and the fourth group of LEDs comprises at least one LED; and
a second capacitor connected in parallel with the third group of LEDs and the fourth group of LEDs.
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Abstract
A circuit serving as a light source, the circuit comprising a first group of light-emitting diodes (LEDs), a second group of LEDs connected in anti-parallel with the first group of LEDs, wherein each of the first group of LEDs and the second group of LEDs comprises at least one LED, and a capacitor connected in parallel with the first group of LEDs and the second group of LEDs.
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Citations
18 Claims
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1. A circuit serving as a light source, the circuit comprising:
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a first set of light-emitting diodes (LEDs); and a second set of LEDs that is connected in series to the first set of LEDs, wherein the first set of LEDs comprises; a first group of LEDs; a second group of LEDs connected in anti-parallel with the first group of LEDs, wherein each of the first group of LEDs and the second group of LEDs comprises at least one LED; and a first capacitor connected in parallel with the first group of LEDs and the second group of LEDs, and wherein the second set of LEDs comprises; a third group of LEDs; a fourth group of LEDs connected in anti-parallel with the third group of LEDs, wherein each of the third group of LEDs and the fourth group of LEDs comprises at least one LED; and a second capacitor connected in parallel with the third group of LEDs and the fourth group of LEDs. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 12, 13, 14, 15, 16, 17, 18)
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7. A circuit serving as a light source, the circuit comprising:
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a first group of light-emitting diodes (LEDs); a second group of LEDs connected in anti-parallel with the first group of LEDs, wherein each of the first group of LEDs and the second group of LEDs comprises at least one LED; a capacitor connected in parallel with the first group of LEDs and the second group of LEDs; an inductor connected in series with the first group of LEDs and the second group of LEDs, wherein the inductor is configured to regulate an overall current flowing through an anti-parallel set composed of the first group of LEDs, the second group of LEDs, and the capacitor; an additional capacitor connected in series with the first group of LEDs and the second group of LEDs and in series with the inductor; and a switch and at least one capacitor connected in series with the switch, wherein the combination of the switch and the at least one capacitor is connected in parallel with the additional capacitor.
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10. A circuit serving as a light source, the circuit comprising:
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a first group of light-emitting diodes (LEDs); a second group of LEDs connected in anti-parallel with the first group of LEDs, wherein each of the first group of LEDs and the second group of LEDs comprises at least one LED; a capacitor connected in parallel with the first group of LEDs and the second group of LEDs; and wiring configured to receive an alternating current (AC) voltage and connected to the first group of LEDs without an intervening AC to direct current (DC) conversion, wherein the capacitor is configured to create a snap action during a transition phase of the AC voltage source such that a voltage across the first group of LEDs has substantially the shape of a square wave, wherein the transition phase occurs when the AC voltage source crosses a zero point, and wherein the square wave of the voltage across the first group of LEDs causes the first group of LEDs and the second group of LEDs to have a relative off-time of less than 15%.
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11. A method for controlling a light-emitting diode (LED)-based light source that operates under an alternating current (AC) source and comprises at least one pair of anti-parallel connected LEDs, the method comprising:
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producing an AC voltage across a pair of LEDs to substantially be a square wave shape; and exciting the pair of LEDs using the AC voltage, wherein producing the AC voltage comprises using a capacitor connected in parallel with the pair of LEDs to create a snap action near a zero-cross event of the AC source, wherein the square wave shape of the AC voltage causes the pair of LEDs to have a relative off-time of less than 10%, and wherein a magnitude of the AC voltage remains smaller than a threshold voltage of the pair of LEDs during the off-time.
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Specification