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US 12,707,539 B2Granted
Method and apparatus for dimming lighting fixtures
AssigneeKorrus, Inc.
InventorsMustafa Homsi, Anthony N. McDougle, Andrew Stangeland, Pujitha Prathipati, Timothy Jay Scott Rogerson
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Abstract
This disclosure pertains to methods, apparatus, circuitry, and techniques for controlling the dimming of lighting fixtures with precision and, particularly, down to very low levels of illumination.
Claims20
A circuit for dimming of a lighting device, the circuit comprising:
- a transistor comprising a gate terminal, a source terminal, and a drain terminal;
- an inductor having a first terminal coupled to the drain terminal of the transistor at a first node and a second terminal coupled to a first terminal of the lighting device;
- a resistor having a first terminal coupled to the source terminal of the transistor;
- a processing device coupled to the gate terminal of the transistor, the processing device configured to detect a voltage at the first node and to provide a voltage at the gate terminal of the transistor that turns the transistor on when it detects that the voltage at the first node is zero volts, the processing device further configured to detect a current through the resistor and configured to provide a voltage at the gate of the transistor that turns the transistor off when it detects the current through the resistor is above a threshold current level, thereby producing a pulse train having a first frequency at the gate of the transistor;
- and
- wherein the processing device is further configured to cyclically enable the pulse train at the gate of the transistor for a first period and disable the pulse train at the gate of the transistor for a second period thereby turning the pulse train on and off at the gate of the transistor at a duty cycle determined by the first period and the second period and at a second frequency lower than the first frequency.
3 more elements
A method of controlling dimming of a lighting device comprising:
- controlling an average current through the lighting device by a combination of:
- applying analog dimming by passing a first signal comprising a periodic current at a first frequency through the lighting device, wherein dimming is achieved by controlling the peak current of the first signal;
- applying first Pulse Width Modulation (PWM) dimming by modulating the first signal ON and OFF with a second signal at a pulse frequency lower than the first frequency, wherein additional dimming is achieved by controlling a duty cycle of the second signal;
- and
- applying second PWM dimming by further increasing the off period of the second signal per cycle to reduce the pulse frequency of the second signal.
2 more elements
A method of controlling dimming of a lighting device comprising:
- controlling an average current through the lighting device by a combination of:
- applying analog dimming by passing a first signal comprising a periodic current at a first frequency through the lighting device, wherein dimming is achieved by controlling the peak current of the first signal;
- applying first Pulse Width Modulation (PWM) dimming by modulating the first signal ON and OFF with a second signal at a pulse frequency lower than the first frequency, wherein additional dimming is achieved by controlling a duty cycle of the second signal down to a predetermined minimum ON period per cycle;
- and
- after the predetermined minimum ON period in the first PWM dimming is reached, applying second PWM dimming by further increasing the off period of the second signal per cycle to reduce the pulse frequency of the second signal.
2 more elements
Dependencies are inferred from the claim text.