Powering high-efficiency lighting devices from a triac-based dimmer
First Claim
1. A circuit for powering one or more lighting devices from an output of a thyristor-switched dimmer circuit coupled to an AC voltage source, the circuit comprising:
- a switching power converter having an input for coupling to the output of the thyristor-switched dimmer circuit, a magnetic storage element for storing energy transferred from the input, and at least one output for supplying energy to the one or more lighting devices from the magnetic storage element; and
a control circuit for operating the switching power converter during an active portion of half cycles of a voltage of the AC voltage source in which the switching power converter transfers energy from the output of the thyristor-switched dimmer circuit, wherein the control circuit determines durations of the active portion of the half cycles such that sufficient energy is transferred from the input to operate the one or more lighting devices until a beginning of an active portion of a subsequent half-cycle, wherein subsequent to the active portion of the half-cycles, a high impedance level is presented to the output of the thyristor-switched dimmer circuit during an idle period that extends until the subsequent half-cycle, wherein the half cycles extend between adjacent zero-crossings of the voltage of the AC voltage source.
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Accused Products
Abstract
A circuit for powering high-efficiency lighting devices from a thyristor-controlled dimmer operates a switching power circuit during active portions of half-cycles of the AC line voltage source that supplies the dimmer. A control circuit determines the durations of the active portions such that sufficient energy is transferred to operate the lighting devices until a next half-cycle of the AC line voltage, at which time the active portion of the half-cycle is terminated. A high impedance level is presented to the output of the dimmer until the next half-cycle commences.
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Citations
21 Claims
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1. A circuit for powering one or more lighting devices from an output of a thyristor-switched dimmer circuit coupled to an AC voltage source, the circuit comprising:
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a switching power converter having an input for coupling to the output of the thyristor-switched dimmer circuit, a magnetic storage element for storing energy transferred from the input, and at least one output for supplying energy to the one or more lighting devices from the magnetic storage element; and a control circuit for operating the switching power converter during an active portion of half cycles of a voltage of the AC voltage source in which the switching power converter transfers energy from the output of the thyristor-switched dimmer circuit, wherein the control circuit determines durations of the active portion of the half cycles such that sufficient energy is transferred from the input to operate the one or more lighting devices until a beginning of an active portion of a subsequent half-cycle, wherein subsequent to the active portion of the half-cycles, a high impedance level is presented to the output of the thyristor-switched dimmer circuit during an idle period that extends until the subsequent half-cycle, wherein the half cycles extend between adjacent zero-crossings of the voltage of the AC voltage source. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of powering one or more lighting devices from an output of a thyristor-switched dimmer circuit, comprising:
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supplying energy to the one or more lighting devices by converting energy drawn from the output of the thyristor-switched dimmer circuit; determining a duration of active portion of half-cycles of a voltage of an AC voltage source that supplies an input of the thyristor-switched dimmer circuit for which the switching power converter transfers energy from the output of the thyristor-switched dimmer circuit, wherein the duration is determined such that sufficient energy is transferred from the input to operate the one or more lighting devices until a beginning of an active portion of a subsequent half-cycle; and controlling an impedance presented to the output of the thyristor-switched dimmer circuit such that a high impedance level is presented to the output of the output of the thyristor-switched dimmer circuit during an idle period immediately subsequent to the active time period, wherein the half cycles extend between adjacent zero-crossings of the voltage of the AC voltage source. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An integrated circuit for operating a circuit that powers one or more lighting devices from an output of a thyristor-switched dimmer circuit, comprising:
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a power converter control circuit having an input for coupling to the output of the thyristor-switched dimmer circuit and an output for controlling a switching power converter for supplying the one or more lighting devices from the output of the thyristor-switched dimmer circuit; and a timing control circuit for operating the switching power converter during an active portion of half cycles of a voltage of the AC voltage source in which the switching power converter transfers energy from the output of the thyristor-switched dimmer circuit, wherein the control circuit determines durations of the active portion of the half cycles such that sufficient energy is transferred from the input to operate the one or more lighting devices until a beginning of an active portion of a subsequent half-cycle, wherein subsequent to the active portion of the half-cycles, a high impedance level is presented to the output of the thyristor-switched dimmer circuit during an idle period that extends until the subsequent half-cycle, wherein the half cycles extend between adjacent zero-crossings of the voltage of the AC voltage source. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification