Inductively coupled ballast circuit
First Claim
1. A ballast circuit comprising:
- an electromagnetic radiation emitting assembly comprising a secondary coil; and
an electronic assembly comprising an inductive coupler, said inductive coupler separated from said electromagnetic radiation emitting assembly by an air gap, aid inductive coupler operable to induce a voltage in said secondary coil when said electronic assembly is energized, wherein a permeance of said air gap is adjustable as a function of a distance between said inductive coupler and said secondary coil, an operating point of said electromagnetic radiation emitting assembly adjustable as a function of said permeance.
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Accused Products
Abstract
A ballast circuit is disclosed for inductively providing power to a load. The ballast circuit includes an oscillator, a driver, a switching circuit, a resonant tank circuit and a current sensing circuit. The current sensing circuit provides a current feedback signal to the oscillator that is representative of the current in the resonant tank circuit. The current feedback signal drives the frequency of the ballast circuit causing the ballast circuit to seek resonance. The ballast circuit preferably includes a current limit circuit that is inductively coupled to the resonant tank circuit. The current limit circuit disables the ballast circuit when the current in the ballast circuit exceeds a predetermined threshold or falls outside a predetermined range.
608 Citations
59 Claims
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1. A ballast circuit comprising:
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an electromagnetic radiation emitting assembly comprising a secondary coil; and
an electronic assembly comprising an inductive coupler, said inductive coupler separated from said electromagnetic radiation emitting assembly by an air gap, aid inductive coupler operable to induce a voltage in said secondary coil when said electronic assembly is energized, wherein a permeance of said air gap is adjustable as a function of a distance between said inductive coupler and said secondary coil, an operating point of said electromagnetic radiation emitting assembly adjustable as a function of said permeance. - View Dependent Claims (2, 3, 4, 6, 7, 8)
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5. The ballast circuit 1, wherein said air gap is operable to perform a current limiting function.
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9. A ballast circuit comprising:
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an electromagnetic radiation emitting assembly comprising a secondary coil electrically connected with an electromagnetic radiation emitting device;
a series resonant tank circuit comprising an inductive coupler, said inductive coupler and said secondary coil operable to form an air core transformer to inductively couple said electromagnetic radiation emitting assembly and said series resonant tank circuit, said secondary coil and said inductive coupler forming a coupling coefficient, an operating point of said electromagnetic radiation emitting device being adjustable as a function of said coupling coefficient;
a half bridge switching circuit tank circuit;
a driver electrically connected with said half bridge switching circuit; and
an oscillator electrically connected with said driver and said series resonant tank circuit, said oscillator operable to direct said half bridge switching circuit with id driver to energize said series resonant tank circuit as a function of feedback from said series resonant tank circuit, said series resonant tank circuit operable to inductively energize said electromagnetic radiation emitting device. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of energizing an electromagnetic radiation emitting device as a load, the method comprising:
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energizing a switching circuit;
energizing a tank circuit with an output of the switching circuit to generate a voltage across an inductive coupler;
inducing a voltage in a secondary winding with said inductive coupler, said secondary winding separated by an air gap from said inductive coupler;
energizing the load with the voltage induced in said secondary winding; and
changing the distance between said inductive coupler and said secondary coil to adjust a coupling coefficient, wherein an operating point of the load is adjustable a function of said coupling coefficient. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A ballast circuit comprising:
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an oscillator;
a driver electrically connected with said oscillator, wherein an output from said oscillator controls said driver;
a switching circuit electrically connected with said driver, wherein an output of said driver controls said switching circuit;
a resonant tank circuit electrically connected with said switching circuit, wherein said resonant tank circuit includes a primary coil; and
a current sensing transformer coupled with said oscillator and said resonant tank circuit, said current sensing transformer sensing current in said resonant tank circuit and providing an input to said oscillator as a function of said sensed current. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
wherein said current limit circuit includes a latch having an output electrically connected to said control circuit, said control circuit enabling and disabling said ballast circuit in response to said output received from said latch, an output of said operational amplifier of said current limit circuit being electrically connected to an input of said latch.
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41. The ballast circuit of claim 40 wherein said current limit circuit includes a reset for resetting said latch.
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42. The ballast circuit of claim 41 wherein said latch is a flip flop.
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43. The ballast circuit of claim 42 wherein said current sensing transformer of said current sensing circuit includes a secondary coil wrapped around a core, said current sensing transformer of said current limit circuit including a secondary coil wrapped around said core.
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44. A ballast circuit comprising:
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a control circuit;
an oscillator electrically connected with said control circuit;
a driver electrically connected with said oscillator, wherein an output from said oscillator controls said driver;
a switching circuit electrically connected with said driver, wherein an output of said driver controls said switching circuit;
a resonant tank circuit electrically connected with said switching circuit, wherein said resonant tank circuit includes a primary coil;
a current sensing circuit electrically connected with said oscillator and said resonant tank circuit, the current sensing circuit including a current sense transformer, said current sensing circuit sensing current in said resonant tank circuit and providing an input to said oscillator as a function of said sensed current; and
a current limit circuit inductively coupled to said resonant tank circuit and electrically connected to said control circuit, wherein said control circuit disables the ballast circuit in response to a predetermined signal from said current limit circuit. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
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Specification