DRIVER CIRCUIT FOR REDUCED FORM FACTOR SOLID STATE LIGHT SOURCE LAMP

• US 20120286663A1
• Filed: 01/20/2012
• Published: 11/15/2012
• Est. Priority Date: 05/12/2011
• Status: Active Grant

• Current Assignee: LEDVANCE LLC (MLS Co. Ltd.)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Dutta, Arunava, Puvanakijjakorn, Voravit, Lei, Sean
• Granted Patent: US 8,674,605 B2
• Time in Patent Office: Days
• US Class Current: 315/85
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/59 for reducing or suppressing flicker or glow effects

Abstract

A solid state light source driver circuit, system and method are provided. The driver circuit includes a rectifier circuit, an energy storage element coupled thereto, a current bleeder circuit coupled thereto, and a switch. The rectifier circuit receives AC input and provides unregulated DC voltage. The switch closes to couple some of the unregulated DC voltage to the energy storage element, and opens to transfer energy to drive the light source. A power factor controller circuit provides an output signal to control the switch. The current bleeder circuit provides supply voltage to the power factor controller circuit within a range and maintains a current flow associated with the AC input that exceeds a predetermined threshold. A constant off-time controller circuit provides a switching frequency control signal to the power factor controller circuit. An EMI filter reduces generated EMI noise.

Claims

1. A driver circuit to drive a solid state light source, comprising:

a rectifier circuit configured to receive an AC input voltage and provide an unregulated DC voltage;

an energy storage element coupled to the rectifier circuit;

a switch, wherein the switch is configured to close so as to couple a portion of the unregulated DC voltage to the energy storage element, and wherein the switch is configured to open so as to transfer energy from the energy storage element to provide a DC output voltage to drive the solid state light source;

a power factor controller circuit configured to provide an output signal to control the switch;

a current bleeder circuit coupled to the rectifier circuit, the current bleeder circuit configured to provide a supply voltage to the power factor controller circuit within a nominal operating range and to maintain a current flow associated with the AC input voltage, wherein the current flow exceeds a predetermined threshold;

a constant off-time controller circuit configured to provide a switching frequency control signal to the power factor controller circuit; and

an electromagnetic interference (EMI) filter configured to reduce EMI noise generated by the driver circuit.

2. The driver circuit of claim 1, wherein the predetermined threshold is based on a nominal operating current requirement of a dimmer circuit to reduce flicker of the solid state light source.

3. The driver circuit of claim 1, further comprising a printed circuit board (PCB) on which the driver circuit is disposed.

4. The driver circuit of claim 3, wherein the PCB has a diameter that does not exceed 1.25 inches.

5. The driver circuit of claim 3, wherein the energy storage element and the EMI filter are disposed on the PCB such that a distance is provided between the energy storage element and the EMI filter that exceeds a preset threshold.

6. The driver circuit of claim 1, wherein the energy storage element is an inductor, and wherein the inductor is shielded with a ferrite material.

7. A solid state light source lamp assembly comprising:

a housing;

a solid state light source disposed within the housing; and

a driver disposed within the housing, the driver comprising;

a rectifier circuit configured to receive an AC input voltage and provide an unregulated DC voltage;

an energy storage element coupled to the rectifier circuit;

a switch, wherein the switch is configured to close so as to couple a portion of the unregulated DC voltage to the energy storage element, and wherein the switch is configured to open so as to transfer energy from the energy storage element to provide a DC output voltage to drive the solid state light source;

a power factor controller circuit configured to provide an output signal to control the switch;

a current bleeder circuit coupled to the rectifier circuit, the current bleeder circuit configured to provide a supply voltage to the power factor controller circuit within a nominal operating range and to maintain a current flow associated with the AC input voltage, wherein the current flow exceeds a predetermined threshold;

a constant off-time controller circuit configured to provide a switching frequency control signal to the power factor controller circuit; and

an electromagnetic interference (EMI) filter configured to reduce EMI noise generated by the driver circuit.

8. The solid state light source lamp assembly of claim 7, wherein the predetermined threshold is based on a nominal operating current requirement of a dimmer circuit to reduce flicker of the solid state light source.

9. The solid state light source lamp assembly of claim 7, further comprising a printed circuit board (PCB) on which the driver circuit is disposed.

10. The solid state light source lamp assembly of claim 9, wherein the PCB has a diameter that does not exceed 1.25 inches.

11. The solid state light source lamp assembly of claim 9, wherein the energy storage element and the EMI filter are disposed on the PCB such that a distance is provided between the energy storage element and the EMI filter that exceeds a preset threshold.

12. The solid state light source lamp assembly of claim 7, wherein the energy storage element is an inductor, and wherein the inductor is shielded with a ferrite material.

13. A method of driving a solid state light source, the method comprising:

receiving an AC input signal;

maintaining a current flow associated with the AC input signal, wherein the current flow exceeds a predetermined threshold;

converting the AC input signal into a regulated DC output;

controlling a power factor of the regulated DC output using a power factor controller circuit;

filtering EMI generated by the converting; and

coupling the regulated DC output to the solid state light source.

14. The method of claim 13, wherein converting comprises operating a switch to energize an inductor configured to be coupled to the solid state light source, and wherein controlling the power factor comprises controlling the switch.

15. The method of claim 14, wherein converting comprises operating a switch to energize an inductor configured to be coupled to the solid state light source, wherein the inductor is shielded with a ferrite material.

16. The method of claim 13, wherein maintaining comprises maintaining a current flow associated with the AC input signal, wherein the current flow exceeds a predetermined threshold based on a nominal operating current requirement of a dimmer circuit to reduce flicker of the solid state light source.