Ballast circuit with independent lamp control
First Claim
1. A method of energizing first and second lamps by two AC input signals, comprising:
- coupling a first AC input signal to a ballast;
coupling a second AC input signal to the ballast;
energizing a first lamp when the first AC input signal is present regardless of whether the second AC input signal is present; and
energizing the second lamp when the second AC input signal is present regardless of whether the first AC input signal is present.
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Accused Products
Abstract
A ballast circuit independently energizes first and second lamps. In one embodiment, an inverter provides a drive signal for energizing the first and second lamps. A first signal detection circuit detects a first AC input signal and a second signal detection circuit detects a second AC input signal, each of which energizes a respective one of first and second lamps. A first lamp control circuit receives a signal from the first signal detector such that the first lamp is energized by the drive signal when the first AC input signal is present. Similarly, a second lamp control circuit receives a signal from the second signal detector such that the second lamp is energized by the drive signal when the second AC input signal is present.
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Citations
34 Claims
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1. A method of energizing first and second lamps by two AC input signals, comprising:
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coupling a first AC input signal to a ballast;
coupling a second AC input signal to the ballast;
energizing a first lamp when the first AC input signal is present regardless of whether the second AC input signal is present; and
energizing the second lamp when the second AC input signal is present regardless of whether the first AC input signal is present. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of energizing first and second lamps, comprising:
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coupling a first AC input signal to a ballast by receiving the first AC input signal on first and second input terminals coupling a second AC input signal to the ballast by receiving the second AC input signal on the second input terminal and a third input terminal;
coupling a first inductor to the first input terminal;
coupling a second inductor to the second input terminal;
energizing a first lamp when the first AC input signal is present regardless of whether the second AC input signal is present; and
energizing the second lamp when the second AC input signal is present regardless of whether the first AC input signal is present;
wherein said steps of energizing said first and second lamps include the step of;
coupling a third inductor to a switching element, wherein the first, second and third inductors are inductively coupled such that flux generated by the first and second inductors cancels each other when the first AC input signal is present, and wherein a signal on the third inductor, when the second AC input signal is present and the first AC input signal is not present, prevents the first lamp from being energized.
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8. A ballast, comprising:
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first, second and third input terminals;
a first signal detector coupled to the first input terminal for detecting a first AC input signal on the first terminal;
a second signal detector coupled to the third input terminal for detecting a second AC input signal on the third terminal;
a drive circuit for receiving the first and second AC input signals and providing an AC drive signal to first and second lamps;
a first lamp control circuit for coupling to the first lamp;
a second lamp control circuit for coupling to the second lamp;
a first signal path connecting the first lamp control circuit to the first signal detector for carrying a first signal corresponding to a presence of the first AC input signal; and
a second signal path connecting the second lamp control circuit to the second signal detector for carrying a second signal corresponding to a presence of the second AC input signal, wherein the first lamp is energized when the first AC input signal is present independently of whether of the second AC input signal is present, and wherein the second lamp is energized when the second AC input signal is present independently of whether the first AC input signal is present. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A ballast circuit, comprising:
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first, second and third AC input terminals, the first and second AC input terminals being adapted for receiving a first AC input signal and the second and third AC input terminals being adapted for receiving a second AC input signal;
a rectifier circuit for receiving the first and second AC input signals and providing a DC output signal;
an inverter circuit for receiving the DC output signal and providing a drive signal for energizing first and second lamps;
a first signal detector coupled to the first AC input terminal and to the rectifier;
a second signal detector coupled to the third AC input terminal and to the rectifier at a point in common with first signal detector;
a first lamp control circuit for coupling to the first lamp, the first lamp control circuit being optically coupled to the first signal detector; and
a second lamp control circuit for coupling to the second lamp, the second lamp control circuit being optically coupled to the second signal detector, wherein the first lamp control circuit allows the AC drive signal to energize the first lamp when the first AC input signal is present independently of whether the second AC input signal is present, and the second lamp control circuit allows the AC drive signal to energize the second lamp when the second AC input signal is present independently of whether the first AC input signal is present. - View Dependent Claims (26, 27, 28)
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29. A ballast for energizing first and second lamps, comprising:
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first, second, and third AC input terminals, wherein the first and second AC input terminals are adapted for receiving a first AC input signal and the second and third AC input terminals are adapted for receiving a second AC input signal;
a first circuit coupled to the first and second AC input terminals for receiving the first AC input signal and providing a first drive signal for energizing the first lamp, the first circuit including a first inverter controlled by a first inverter disable circuit;
a second circuit coupled to the second and third AC input terminals for receiving the second AC input signal and providing a second drive signal for energizing the second lamp, the second circuit including a second inverter controlled by a second inverter control circuit;
a first inductor coupled to the first AC input terminal;
a second inductor coupled to the second AC input terminal; and
a third inductor inductively coupled to the first and second inductors, the third inductor forming a part of the first inverter disable circuit, wherein a signal generated on the third inductor when the second AC input signal is present and the first AC input signal is not present is effective to disable the first inverter. - View Dependent Claims (30, 31, 32)
a fourth inductor coupled to the second AC input terminal; a fifth inductor coupled to the third AC input terminal; and
a sixth inductor inductively coupled to the fourth and fifth inductors, the sixth inductor forming a part of the second inverter disable circuit, wherein a signal generated on the sixth inductor when the first AC input signal is present and the second AC input signal is not present is effective to disable the second inverter.
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31. The ballast according to claim 29, further including a first capacitor coupled to the fourth inductor such that a voltage on the first capacitor generated by the sixth inductor above a predetermined level is effective to disable the first inverter.
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32. The ballast according to claim 31, further including a first diac coupled to the first capacitor.
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33. A ballast for energizing first and second lamps, comprising:
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first, second and third AC input terminals, the first and second AC input terminals for receiving a first AC input signal, and the second and third AC input terminals for receiving a second AC input signal;
a drive circuit for receiving the first and second AC input signals and energizing the first and second lamps, wherein the drive circuit energizes the first lamp when the first AC input signal is present at the first and second input terminals independently of whether the second AC input signal is present, and wherein the drive circuit energizes the second lamp when the second AC input signal is present independently of whether the first AC input signal is present.
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34. A method of energizing first and second lamps, comprising:
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coupling a first AC input signal to first and second AC input terminals of a ballast;
coupling a second AC input signal to a third terminal and the second terminal of the ballast;
energizing the first lamp when the first AC input signal is present on the first and second AC input terminals of the ballast; and
energizing the second lamp when the second AC input signal is present on the second and third AC input terminals of the ballast.
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Specification