Circuit arrangement for operating a discharge lamp

• US 5,866,989 A
• Filed: 07/07/1997
• Issued: 02/02/1999
• Est. Priority Date: 09/11/1996
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Hendrix, Machiel A. M.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): VU, DAVID HUNG
• Application Number:
  US08/888,901
• Time in Patent Office: 575 Days
• Field of Search: 315/209 R, 315/224, 315/239, 315/219, 315/DIG. 5, 315/272, 315/187, 315/352, 315/247
• US Class Current: 315/209.00R
• CPC Class Codes: H05B 41/28 using static converters
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp

Abstract

A circuit arrangement for operating a discharge lamp. Input terminals are coupled to the poles of a supply voltage source which delivers a low frequency supply voltage. A rectifier is coupled to the input terminals for rectifying the low frequency supply voltage. A branch interconnects output terminals of the rectifier and includes a series arrangement of a first diode, a second diode, and a third diode. The first and second diodes are shunted by a first capacitor. The second and third diodes are shunted by a second capacitor. A resistor passes current during lamp operation with which the first and second capacitors are charged. Lamp current is generated based on the voltages across the first and second capacitors. The resistor is placed in a branch which passes a low frequency alternating current during lamp operation and which connects an input terminal to an input of the rectifier. The circuit arrangement has a high power factor. Radio frequency interference generated in producing the lamp current is effectively suppressed.

Claims

1. A circuit arrangement for operating a discharge lamp, comprising:

input terminals for coupling to the poles of a supply voltage source which delivers a low-frequency supply voltage,

rectifying means provided with inputs coupled to the input terminals for rectifying the low-frequency supply voltage, and provided with output terminals,

a branch which interconnects the output terminals and which comprises a series arrangement of first unidirectional means, second unidirectional means, and third unidirectional means, the first and the second unidirectional means being shunted by first capacitive means, and the second and the third unidirectional means being shunted by second capacitive means,

an ohmic resistor which passes a current during lamp operation with which the first and the second capacitive means are charged, and

means for generating a lamp current from the voltages present across the first and the second capacitive means,

characterized in that the ohmic resistor forms part of a branch which passes a low-frequency alternating current during lamp operation and which connects an input terminal to an input of the rectifying means.

2. A circuit arrangement as claimed in claim 1, wherein the first, second, and third unidirectional means each comprise a diode.

3. A circuit arrangement as claimed in claim 2, wherein the rectifying means comprise a diode bridge.

4. A circuit arrangement as claimed in claim 3, wherein the capacitance value of the first capacitive means is equal to the capacitance value of the second capacitive means.

5. A circuit arrangement as claimed in claim 2, wherein the capacitance value of the first capacitive means is equal to the capacitance value of the second capacitive means.

6. A circuit arrangement as claimed in claim 1, wherein the rectifying means comprise a diode bridge.

7. A circuit arrangement as claimed in claim 6, wherein the capacitance value of the first capacitive means is equal to the capacitance value of the second capacitive means.

8. A circuit arrangement as claimed in claim 1, wherein the capacitance value of the first capacitive means is equal to the capacitance value of the second capacitive means.