Patent ID: 7830093

Claim:
A method for assembling 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 method comprising: assembling into a light fixture a ballast and a gas discharge lamp; assembling into the ballast a comparator circuit such that the comparator circuit: compares a measure signal indicative of a measured value of a lamp parameter with a threshold hold signal indicative of a threshold value of said lamp parameter; and provides a compare signal indicative of the comparison; assembling into the ballast a clamp circuit such that the clamp circuit: receives the compare signal; and provides a clamp signal indicative of a result of the comparison; and assembling into the ballast a control circuit such that the control circuit: receives the clamp signal; and in accordance with the clamp signal, performs one of: reducing the lamp light output level to the low lamp light output level when the clamp signal is indicative of the measured value of the lamp parameter being less than the threshold value of the lamp parameter; or reducing the lamp light output level to an intermediate lamp light output level when the clamp signal is indicative of the measured value of the lamp parameter being greater than or equal to the threshold value of the lamp parameter and subsequently reducing the lamp light output level to the low lamp light output level when the clamp signal subsequently is indicative of the measured value of the lamp parameter being less than the threshold value of the lamp parameter.