System and method for reducing flicker of compact gas discharge lamps at low lamp light output level
First Claim
1. A ballast for stably dimming a lamp light output level of a gas discharge lamp to a low lamp light output level without observable flicker, said ballast comprising:
- a comparator circuit for;
comparing a measure signal indicative of a measured value of a lamp parameter with a threshold signal indicative of a threshold value of said lamp parameter; and
providing a compare signal indicative of said comparison; and
a clamp circuit for;
receiving said compare signal; and
providing a clamp signal indicative of a result of said comparison; and
a control circuit for;
receiving said clamp signal; and
in accordance with said clamp signal, reducing the lamp light output level to an intermediate lamp light output level and subsequently reducing the lamp light output level to the low lamp light output level.
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Accused Products
Abstract
A lamp lighting system allows dimming of a compact gas discharge lamp to a low light output level without perceptible flicker. When the system receives a request to dim the lamp to the low level, the lamp is operated at an intermediate output level prior to operating the lamp is then requested low level. When the lamp cools to below a threshold temperature, the lamp is then operated at the requested low level. In one embodiment, the lamp is dimmed from its full rated output level to 1% of its full rated output level. The intermediate level is approximately 2% to 5% of this full rated level. No flicker is perceived when the lamp level is reduced from the full rated level to the low level. Upon cooling, no flicker and no change in output level are perceived when the lamp is subsequently reduced from the intermediate level to the low level.
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Citations
22 Claims
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1. A ballast for stably dimming a lamp light output level of a gas discharge lamp to a low lamp light output level without observable flicker, said ballast comprising:
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a comparator circuit for;
comparing a measure signal indicative of a measured value of a lamp parameter with a threshold signal indicative of a threshold value of said lamp parameter; and
providing a compare signal indicative of said comparison; and
a clamp circuit for;
receiving said compare signal; and
providing a clamp signal indicative of a result of said comparison; and
a control circuit for;
receiving said clamp signal; and
in accordance with said clamp signal, reducing the lamp light output level to an intermediate lamp light output level and subsequently reducing the lamp light output level to the low lamp light output level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A light fixture for stably dimming a lamp light output level of a gas discharge lamp to a low lamp light output level without observable flicker, said light fixture comprising:
a ballast comprising;
a comparator circuit for;
comparing a measure signal indicative of a measured value of a lamp parameter with a threshold signal indicative of a threshold value of said lamp parameter; and
providing a compare signal indicative of said comparison; and
a clamp circuit for;
receiving said compare signal; and
providing a clamp signal indicative of a result of said comparison; and
a control circuit for;
receiving said clamp signal; and
in accordance with said clamp signal, reducing the lamp light output level to an intermediate lamp light output level and subsequently reducing the lamp light output level to the low lamp light output level. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
Specification