Lamp driver circuit

• US 20070057642A1
• Filed: 09/15/2005
• Published: 03/15/2007
• Est. Priority Date: 09/15/2005
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: InFocus Corporation (Lap-Shun Hui, MBA)
• Inventors: Pruett, H.
• Granted Patent: US 7,541,746 B2
• Time in Patent Office: Days
• US Class Current: 315/247
• CPC Class Codes: H05B 41/28 using static converters

Abstract

A lamp driver circuit is disclosed. The lamp driver circuit comprises a passive power factor correction (PFC) circuit. The passive PFC circuit, in operation, is coupled with an alternating-current (AC) power source. The lamp driver circuit further includes a direct-current to direct-current (DC-DC) power converter coupled with the passive PFC circuit. The DC-DC power converter, in conjunction with the passive PFC circuit, operates as a constant energy converter. The lamp driver circuit also includes a lamp circuit coupled with the DC-DC power converter.

Claims

1. A lamp driver circuit comprising;

a passive power factor correction (PFC) circuit, wherein the passive PFC circuit, in operation, is coupled with an alternating-current (AC) power source;

a direct-current to direct-current (DC-DC) power converter coupled with the passive PFC circuit, wherein the DC-DC power converter, in conjunction with the passive PFC circuit, operates as a constant energy converter; and

a lamp circuit coupled with the DC-DC power converter.

2. The lamp driver circuit of claim 1, wherein the lamp circuit comprises:

a lamp igniter circuit coupled with the DC-DC power converter; and

a lamp bulb coupled with the lamp igniter.

3. The lamp driver circuit of claim 2, wherein the lamp bulb comprises a high-pressure, short-arc lamp bulb.

4. The lamp driver circuit of claim 1, wherein the passive PFC circuit comprises a valley-fill circuit.

5. The lamp driver circuit of claim 1, wherein the valley-fill circuit comprises:

a bridge rectifier circuit coupled with the AC power source; and

a charge storage and delivery circuit coupled with, and between, the bridge rectifier circuit and the DC-DC power converter.

6. The lamp driver circuit of claim 5, wherein the charge storage and delivery circuit comprises:

a plurality of capacitors;

a plurality of diodes; and

at least one resistor,

wherein the plurality of capacitors, the plurality of diodes and the at least one resistor are arranged such that, in operation, the plurality of capacitors charge in series when a line voltage associated with the AC power source is greater than a threshold level and the plurality of capacitors discharge in parallel when the line voltage is less than the threshold level.

7. The lamp driver circuit of claim 6, wherein the threshold level is one-half of a nominal peak value of the line voltage.

8. The lamp driver circuit of claim 1, further comprising:

an electromagnetic interference (EMI) filter coupled with the passive PFC circuit, wherein, in operation, the passive PFC circuit is coupled with the AC power source via the EMI filter.

9. The lamp driver circuit of claim 8, wherein the EMI filter comprises a resistive, inductive, capacitive circuit.

10. The lamp driver circuit of claim 1, wherein the DC-DC power converter comprises a flyback DC-DC power converter that, in operation, operates discontinuously.

11. The lamp driver circuit of claim 1, wherein the DC-DC power converter comprises a buck-boost converter that, in operation, operates discontinuously.

12. A lamp driver circuit comprising:

an electromagnetic interference (EMI) filter, wherein the EMI filter, in operation, is coupled with an alternating-current (AC) power source;

a passive power factor correction (PFC) circuit coupled with the EMI filter;

a direct-current to direct-current (DC-DC) power converter coupled with the passive PFC circuit, wherein the DC-DC power converter, in conjunction with the passive PFC circuit, operates as a constant energy converter; and

a lamp circuit coupled with the DC-DC power converter.

13. The lamp driver circuit of claim 12, wherein the passive PFC circuit comprises a valley fill circuit.

14. The lamp driver circuit of claim 12, wherein the DC-DC converter comprises a flyback DC-DC converter that, in operation, operates discontinuously.

15. The lamp driver circuit of claim 12, wherein the DC-DC converter comprises a buck-boost DC-DC converter that, in operation, operates discontinuously.

16. A lamp driver circuit comprising:

a passive power factor correction (PFC) circuit, wherein the passive PFC circuit, in operation, is coupled with an alternating-current (AC) power source;

a direct-current to direct-current (DC-DC) power converter coupled with the passive PFC circuit, wherein the DC-DC power converter, in conjunction with the passive PFC circuit, operates as a constant energy converter, and wherein the DC-DC converter operates discontinuously; and

a lamp circuit coupled with the DC-DC power converter.

17. The lamp driver circuit of claim 16, wherein the passive PFC circuit, in operation:

rectifies an AC power signal generated by the AC power source to generated a rectified signal; and

stores a substantially fixed amount of electrical energy and delivers that fixed amount of electrical energy to the DC-DC converter each period of the AC power signal,

wherein electrical energy is stored while the rectified signal is above a threshold level and the stored electrical energy is delivered to the DC-DC power converter while the rectified signal is below the threshold level.

18. The lamp driver circuit of claim 17, wherein the threshold level is approximately one-half a nominal peak value of a line voltage of the AC power source.

19. The lamp driver circuit of claim 16, wherein the DC-DC converter comprises a flyback DC-DC converter.

20. The lamp driver circuit of claim 16, wherein the DC-DC converter comprises a buck-boost DC-DC converter.