Koninklijke Philips Corporation N.V.

Steven Pilgrim

Robert Alexander Erhardt

Raymond Kulka

Ching-Yao Hung

Control circuitry for controlling the output power of an electronic ballast system having a power supply branch circuit having power lines comprising a line voltage line and a common line, and a ballast stage having (i) inputs connected to the power lines for providing power to the lamp, (ii) internal power control feedback circuitry that defines a feedback loop for controlling the amount of power applied to the lamp, and (iii) a control signal input for receiving a control signal that affects operation the internal power control feedback circuitry and the level of power outputted by the ballast stage. The control circuitry comprises a first circuit having an input for connection to one of the power lines. The first circuit generates a control signal for input into the control input of the ballast stage. The control circuitry having a first predetermined magnitude when one of the power lines is connected to the input of the first circuit and a second predetermined magnitude when the power lines are isolated from the input of the first circuit. The control circuitry further comprises a second circuit having a first state for reducing the first and second predetermined magnitudes of the control signal by a predetermined increment so as to effect step dimming of the lamp and a second state that maintains the first and second predetermined magnitudes of the control signal.

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Waukegan, IL, United States of America

Steven Pilgrim