Method and apparatus for determining a target light intensity from a phase-control signal
AssigneeLutron Technology Company LLC
InventorDonald F. Hausman, Jr.
Life of this patent
Estimating the term…
Abstract
A dimmable ballast circuit for a compact fluorescent lamp controls the intensity of a lamp tube in response to a phase-control voltage received from a dimmer switch. The ballast circuit comprises a phase-control-to-DC converter circuit that receives the phase-control voltage, which is characterized by a duty cycle defining a target intensity of the lamp tube, and generates a DC voltage representative of the duty cycle of the phase-control voltage. Changes in the duty cycle of the phase-control voltage that are below a threshold amount are filtered out by the converter circuit, while intentional changes in the duty cycle of the phase-control voltage are reflected in changes in the target intensity level and thereby the intensity level of the lamp tube.
Claims14
A lamp configured to receive a phase-control voltage characterized by a duty cycle, the lamp comprising:
- a lighting load;
- a load regulation circuit configured to receive a drive control signal and to control an intensity level of the lighting load in response to the drive control signal;
- a control circuit configured to receive a signal representative of the intensity level of the lighting load, and to generate the drive control signal to cause the load regulation circuit to adjust the intensity level of the lighting load towards a target level;
- an enclosure for housing the load regulation circuit;
- and
- a screw-in base adapted to be coupled to a standard Edison socket;
- wherein the control circuit is configured to determine the target level for the lighting load in response to the duty cycle of the phase-control voltage, the control circuit configured to adjust the target level for the lighting load using a first time constant in response to changes in the duty cycle of the phase-control voltage that are less than a threshold amount, and to adjust the target level for the lighting load using a second time constant in response to changes in the duty cycle of the phase-control voltage that are greater than the threshold amount, where the second time constant is less than the first time constant.
Dependencies are inferred from the claim text.