Circuit apparatus and method for operating a lamp

• US 7,053,561 B2
• Filed: 07/23/2003
• Issued: 05/30/2006
• Est. Priority Date: 08/01/2002
• Status: Active Grant

• Current Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Original Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Inventors: Storm, Arwed, Mayer, Siegfried
• Primary Examiner(s): Dinh, Trinh V
• Assistant Examiner(s): A, MINH D
• Application Number:
  US10/624,575
• Publication Number:
  US 20040245942A1
• Time in Patent Office: 1,042 Days
• Field of Search: 315/291, 315/224, 315/307, 315/DIG.5, 315/DIG.7, 315/225, 315/194, 315/209.R
• US Class Current: 315/209.00R
• CPC Class Codes: H05B 41/2856 against internal abnormal circuit conditions
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

The current through the components of a half-bridge of an electronic ballast is intended to be limited during the starting phase. For this purpose, the gate of a half-bridge transistor (T2) is driven by a current limiting circuit (D1, D2, D3, T3, C3) in such a way that the current through the transistors (T1, T2) is limited during the starting phase, whereas it remains unlimited during the glow phase and burning phase of the lamp (LA).

Claims

1. A circuit for operating a discharge lamp (LA), the circuit comprising:

an inverter (T1,T2) for supplying the lamp with alternating current, the inverter having an operating frequency, the inverter comprising;

at least one transistor switching unit (T2) having a gate; and

a current limiting device (T3,D1,D2,D3,C3) coupled to the gate of the at least one transistor switching unit (T2), wherein the current limiting device is operable to switch the at least one transistor unit on and off as a function of a current flowing through the at least one transistor unit;

a load circuit (L1-A,C1,C2) connected between the inverter and the lamp, the load circuit having a resonant frequency; and

a phase setting device (R2,C2,L2) connected to the gate of the at least one transistor switching unit (T2), the phase setting device being operable to match the operating frequency of the inverter to the resonant frequency of the load circuit.

2. A circuit for operating a discharge lamp (LA), the circuit comprising:

an inverter (T1,T2) for supplying the lamp with alternating current, the inverter having an operating frequency, the inverter comprising;

at least one transistor switching unit (T2) having a gate; and

a current limiting device (T3,D1,D2,D3,C3) coupled to the gate of the at least one transistor switching unit (T2), wherein the current limiting device is operable to switch the at least one transistor unit on and off as a function of a current flowing through the at least one transistor unit; and

wherein;

the at least one transistor switching unit (T2) is connected to ground via a first resistor (R1); and

the current limiting device comprises;

a switching device (T3) having a base, an emitter, and a collector, wherein the emitter is connected to ground;

a capacitor (C3) coupled between the base of the switching device (T3) and ground;

a first zener diode (D2) coupled between the first resistor (R1) and the base of the switching device (T3);

a second zener diode (D2) coupled between the collector of the switching device (T3) and ground; and

a third zener diode (D3) coupled between the gate of the at least one transistor switching unit (T2) and the collector of the switching device (T3).

3. A circuit for operating a discharge lamp (LA), the circuit comprising:

an inverter (T1,T2) for supplying the lamp with alternating current, the inverter having an operating frequency, the inverter comprising;

at least one transistor switching unit (T2) having a gate; and

a current limiting device (T3,D1,D2,D3,C3) coupled to the gate of the at least one transistor switching unit (T2), wherein the current limiting device is operable to switch the at least one transistor unit on and off as a function of a current flowing through the at least one transistor unit; and

wherein;

the at least one transistor switching unit (T2) is connected to ground via a first resistor (R1); and

the current limiting device comprises;

a switching device (T3) having a base, an emitter, and a collector, wherein the emitter is connected to ground;

a capacitor (C3) coupled between the base of the switching device (T3) and ground;

a first zener diode (D1) coupled between the first resistor (R1) and the base of the switching device (T3);

a second zener diode (D2) coupled between the collector of the switching device (T3) and ground; and

a third zener diode (D3) coupled between the gate of the at least one transistor switching unit (T2) and the collector of the switching device (T3);

a load circuit (L1-A,C1,C2) connected between the inverter and the lamp, the load circuit having a resonant frequency; and

a phase setting device (R2,C2,L2) connected to the gate of the at least one transistor switching unit (T2), the phase setting device being operable to match the operating frequency of the inverter to the resonant frequency of the load circuit.