Solid state light source driving and dimming using an AC voltage source
First Claim
1. A solid state light source driving and dimming system, comprising:
- a plurality of solid state light source driver circuits configured to be coupled to an AC voltage source, each driver circuit comprising;
a constant current circuitry coupled to the AC voltage source, wherein the constant current circuitry is configured to generate a constant AC current from the AC voltage source;
rectifier circuitry coupled to the constant current circuitry and configured to generate a DC current to drive at least one solid state light source;
shunt circuitry coupled to a negative voltage rail and a positive voltage rail of the AC voltage source;
switch circuitry coupled to the shunt circuitry; and
pulse width modulation (PWM) circuitry configured to generate a PWM signal to control a conduction state of the switch circuitry;
wherein when the switch circuitry is closed, a conduction path exists between the AC voltage source and the shunt circuitry through the switch circuitry to discontinue the DC current, and when the switch circuitry is closed, the shunt circuitry is electrically decoupled from the AC voltage source.
2 Assignments
0 Petitions
Accused Products
Abstract
Solid state light source driving and dimming systems are provided that enable a plurality of solid state light source (e.g., LED) driver circuits to be coupled to a single AC voltage source. The driver circuits may include constant current circuitry configured to generate a constant AC current from the AC voltage source, and rectifier circuitry configured to generate a DC current to drive the solid state light source (e.g., LEDs). Dimming control includes shunt circuitry operable with a PWM switch to shunt the AC voltage source during certain portions of a PWM signal and to decouple the shunt circuitry from the AC voltage source during other portions of the PWM signal. Shunting the AC voltage source causes the interruption of the DC current to effectively turn off the LEDs. Decoupling the shunt circuitry may improve overall efficiency of power transfer to the LEDs.
-
Citations
20 Claims
-
1. A solid state light source driving and dimming system, comprising:
-
a plurality of solid state light source driver circuits configured to be coupled to an AC voltage source, each driver circuit comprising; a constant current circuitry coupled to the AC voltage source, wherein the constant current circuitry is configured to generate a constant AC current from the AC voltage source; rectifier circuitry coupled to the constant current circuitry and configured to generate a DC current to drive at least one solid state light source; shunt circuitry coupled to a negative voltage rail and a positive voltage rail of the AC voltage source; switch circuitry coupled to the shunt circuitry; and pulse width modulation (PWM) circuitry configured to generate a PWM signal to control a conduction state of the switch circuitry; wherein when the switch circuitry is closed, a conduction path exists between the AC voltage source and the shunt circuitry through the switch circuitry to discontinue the DC current, and when the switch circuitry is closed, the shunt circuitry is electrically decoupled from the AC voltage source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A solid state light source driving and dimming system, comprising:
-
a plurality of solid state light source driver circuits configured to be coupled to an AC voltage source, each driver circuit comprising; constant current circuitry coupled to an AC voltage source, the constant current circuitry is configured to generate a constant AC current from the AC voltage source; isolation circuitry coupled to the AC voltage source and configured to electrically isolate each driver circuit from each other; rectifier circuitry coupled to the constant current circuitry and configured to generate a DC current to drive at least one solid state light source; shunt circuitry coupled to a negative and positive voltage rails of the AC voltage source; switch circuitry coupled to the shunt circuitry; and pulse width modulation (PWM) circuitry configured to generate a PWM signal to control a conduction state of the switch circuitry; wherein when the switch circuitry is closed, a conduction path exists between the AC voltage source and the shunt circuitry through the switch circuitry to discontinue the DC current, and when the switch circuitry is closed, the shunt circuitry is electrically decoupled from the AC voltage source. - View Dependent Claims (15, 16, 17)
wherein when the switch is closed, the AC voltage source is shunted through the first, second and third diodes to discontinue the DC current to the at least one solid state light source.
-
-
16. The solid state light source driving and dimming system of claim 14, wherein the isolation circuitry comprises a capacitor coupled to the negative voltage rail and the constant current circuitry comprises a capacitor coupled to the positive voltage rail, and wherein the capacitance of the isolation circuitry and the constant current circuitry are approximately equal.
-
17. The solid state light source driving and dimming system of claim 14, wherein the switch circuitry, the PWM circuitry, the rectifier circuitry and the at least one solid state light source are coupled to a common ground.
-
18. A solid state light source driving and dimming system, comprising:
-
an isolation transformer having a primary winding coupled to an AC voltage source and a plurality of secondary windings, wherein the isolation transformer is configured to electrically isolate each respective secondary winding from each other; a plurality of solid state light source driver circuits configured to be coupled to a respective secondary winding, each driver circuit comprising; constant current circuitry coupled to a secondary winding, the constant current circuitry is configured to generate a constant AC current from the AC voltage source; rectifier circuitry coupled to the constant current circuitry and configured to generate a DC current to drive at least one solid state light source; shunt circuitry coupled to a negative and positive voltage rails of the secondary winding; switch circuitry coupled to the shunt circuitry; and pulse width modulation (PWM) circuitry configured to generate a PWM signal to control a conduction state of the switch circuitry; wherein when the switch circuitry is closed, a conduction path exists between the secondary winding and the shunt circuitry through the switch circuitry to discontinue the DC current, and when the switch circuitry is closed, the shunt circuitry is electrically decoupled from the secondary winding. - View Dependent Claims (19, 20)
wherein when the switch is closed the secondary winding is shunted through the first, second and third diodes to discontinue the DC current to the at least one solid state light source.
-
-
20. The solid state light source driving and dimming system of claim 18, wherein the switch circuitry, the PWM circuitry, the rectifier circuitry and the at least one solid state light source are coupled to a common ground.
Specification