Power supply circuit for a discharge lamp

• US 5,399,943 A
• Filed: 12/24/1992
• Issued: 03/21/1995
• Est. Priority Date: 12/24/1992
• Status: Expired due to Fees

• Current Assignee: Bank One, Wisconsin (JP Morgan Chase & Co)
• Original Assignee: Micro-Technology Inc.
• Inventors: Chandrasekaran, T.
• Primary Examiner(s): Pascal, Robert J.
• Assistant Examiner(s): Philogene, Haissa
• Application Number:
  US07/996,683
• Time in Patent Office: 817 Days
• Field of Search: 315/219, 315/276, 315/278, 315/307, 315/200 R, 315/209 R, 315/224, 315/324, 315/DIG. 5, 315/DIG. 7
• US Class Current: 315/219
• CPC Class Codes: H02M 7/53832 in a push-pull arrangement
• CPC Class Codes: H05B 41/282 with semiconductor devices H05B41/2806, H05B41/288, H05B41/295 take precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

An electronic power supply for use with a gas discharge lamp, including a transformer having its primary winding connected in parallel with a capacitor of a series resonant element connected between an inverter and the lamp, effective to limit the voltage from the power supply to a predetermined level.

Claims

1. A power supply circuit for a gas discharge lamp comprising:

an inverter circuit connected to a source of direct current;

said inverter circuit including the first and second switching transistors;

a first transformer including a primary winding, first and second secondary windings;

said first secondary winding, 180 degrees out of phase with said second secondary winding;

said first and second secondary windings each including a circuit connection to said first and second switching transistors, respectively;

a resonant element consisting of an inductor and a capacitor connected in series between said lamp and said inverter circuit;

means to ensure said first transformer senses a zero crossing of current comprising a pair of oppositely poled diodes connected in parallel with said primary winding of said first transformer;

a second transformer connected in parallel with said resonant element capacitor;

said second transformer including at least two primary windings;

whereby said second transformer operates to limit the voltage of said power supply to a predetermined level.

2. A power supply circuit as claimed in claim 1 wherein:

said second transformer includes at least two primary windings;

and at least two secondary windings connected to said lamp to provide isolated heater voltage for operation of said lamp.

3. A power supply circuit as claimed in claim 2 wherein:

there is further included at least one additional capacitor connected between an associated secondary winding and said lamp.

4. A power supply circuit as claimed in claim 1 wherein:

said second transformer further includes a secondary winding;

and rectifier means connected to said secondary winding operated to provide direct current from said power supply to said lamp.

5. A power supply circuit as claimed in claim 4 wherein:

there is further included a filter means connected between said rectifier means and said lamp.

6. A power supply circuit as claimed in claim 1 wherein:

said switching transistors are each of the bipolar type.

7. A power supply circuit as claimed in claim 1 wherein:

said second transformer includes at least two secondary windings connected to said lamp to provide isolated heater voltage for operation of said lamp.

8. A power supply circuit as claimed in claim 1 wherein:

there is further included a circuit connection from said resonant element through said capacitor to said lamp.

9. A power supply circuit as claimed in claim 1 wherein:

there is further included at least one additional capacitor forming a circuit connection from said resonant element to said associated lamp.