CIRCUIT AND METHOD FOR PREHEATING FILAMENTS AND BALLAST

• US 20130175945A1
• Filed: 09/01/2011
• Published: 07/11/2013
• Est. Priority Date: 09/21/2010
• Status: Abandoned Application

• Current Assignee: OSRAM Licht AG (Ams-Osram AG)
• Original Assignee: OSRAM Licht AG (Ams-Osram AG)
• Inventors: Chen, Wei, Guo, Yuancheng, Jian, Jie Hong, Xu, Hui Ling
• Application Number:
  US13/811,281
• Publication Number:
  US 20130175945A1
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/04 Starting switches
• CPC Class Codes: H05B 41/044 for lamp provided with pre-heating electrodes
• CPC Class Codes: H05B 41/295 with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps

Abstract

A circuit for preheating filaments may include: a transistor; a first winding, one terminal of which being electrically connected with a collector of the transistor, and the other terminal being connected to an input of a power source; a second winding, one terminal of which being electrically connected with an emitter of the transistor, the other terminal being electrically connected with a base of the transistor, and the second winding being coupled with the first winding in a self-excitation mode; one or more load windings respectively connected with the filaments in series, and each of which being coupled with the first winding in a flyback mode; and a delay switch, configured to change into an on state from an off state when a trigger signal with a predetermined delay is received, so as to turn off the transistor.

Claims

1. A circuit for preheating filaments, comprising:

a transistor;

a first winding, one terminal of which being electrically connected with a collector of the transistor, and the other terminal being connected to an input of a power source;

a second winding, one terminal of which being electrically connected with an emitter of the transistor, the other terminal being electrically connected with a base of the transistor, and the second winding being coupled with the first winding in a self-excitation mode;

one or more load windings respectively connected with the filaments in series, each of which being coupled with the first winding in a flyback mode; and

a delay switch, configured to change into an on state from an off state when a trigger signal with a predetermined delay is received, so as to turn off the transistor.

2. The circuit for preheating filaments as claimed in claim 1, wherein both terminals of the delay switch are connected with the base and the emitter of the transistor respectively.

3. The circuit for preheating filaments as claimed in claim 1, wherein one terminal of the delay switch is electrically connected with the base of the transistor, and the other terminal is grounded,

4. The circuit for preheating filaments as claimed in claim 1, wherein the trigger signal is generated by a delay circuit, and the trigger signal simultaneously starts up a half-bridge circuit being connected with the circuit for preheating filaments in parallel.

5. The circuit for preheating filaments as claimed in claim 4, wherein the delay circuit is included in the half-bridge circuit.

6. The circuit for preheating filaments as claimed in claim 4, wherein the delay circuit is out of the half-bridge circuit, and is connected with the half-bridge circuit and the circuit for preheating filaments in parallel respectively.

7. The circuit for preheating filaments as claimed in claim 1, further comprising one or more capacitors connected in series between the second winding and the base of the transistor.

8. The circuit for preheating filaments as claimed in claim 1, further comprising one or more resistors connected in series between the second winding and the base of the transistor.

9. The circuit for preheating filaments as claimed in claim 1, further comprising a Zener diode, a cathode of which being electrically connected with the base of the transistor, and an anode of the Zener diode being electrically connected with the emitter of the transistor.

12. The circuit for preheating filaments as claimed in claim 2, further comprising one or more capacitors connected in series between the second winding and the base of the transistor.

13. The circuit for preheating filaments as claimed in claim 3, further comprising one or more capacitors connected in series between the second winding and the base of the transistor.

14. The circuit for preheating filaments as claimed in claim 4, further comprising one or more capacitors connected in series between the second winding and the base of the transistor.

15. The circuit for preheating filaments as claimed in claim 2, further comprising one or more resistors connected in series between the second winding and the base of the transistor.

16. The circuit for preheating filaments as claimed in claim 3, further comprising one or more resistors connected in series between the second winding and the base of the transistor.

17. The circuit for preheating filaments as claimed in claim 4, further comprising one or more resistors connected in series between the second winding and the base of the transistor.

18. The circuit for preheating filaments as claimed in claim 2, further comprising a Zener diode, a cathode of which being electrically connected with the base of the transistor, and an anode of the Zener diode being electrically connected with the emitter of the transistor.

19. The circuit for preheating filaments as claimed in claim 3, further comprising a Zener diode, a cathode of which being electrically connected with the base of the transistor, and an anode of the Zener diode being electrically connected with the emitter of the transistor.

20. The circuit for preheating filaments as claimed in claim 4, further comprising a Zener diode, a cathode of which being electrically connected with the base of the transistor, and an anode of the Zener diode being electrically connected with the emitter of the transistor.

10. A method for preheating filaments using a circuit for preheating filaments, the circuit comprising:

a transistor;

a first winding, one terminal of which being electrically connected with a collector of the transistor, and the other terminal being connected to an input of a power source;

a second winding, one terminal of which being electrically connected with an emitter of the transistor, the other terminal being electrically connected with a base of the transistor, and the second winding being coupled with the first winding in a self-excitation mode;

one or more load windings respectively connected with the filaments in series, each of which being coupled with the first winding in a flyback mode; and

a delay switch, configured to change into an on state from an off state when a trigger signal with a predetermined delay is received, so as to turn off the transistor,

the method comprising;

setting, when power is on, the delay switch in the circuit for preheating filaments to an off state to start up the circuit for preheating filaments; and

sending, after passing a predetermined delay, a trigger signal to the delay switch in the circuit for preheating filaments, and setting the switch to an on state to cut off the circuit for preheating filaments.

11. A ballast, comprising;

a circuit for preheating filaments, the circuit comprising;

a transistor;

a first winding, one terminal of which being electrically connected with a collector of the transistor, and the other terminal being connected to an input of a power source;

a second winding, one terminal of which being electrically connected with an emitter of the transistor, the other terminal being electrically connected with a base of the transistor, and the second winding being coupled with the first winding in a self-excitation mode;

one or more load windings respectively connected with the filaments in series, each of which being coupled with the first winding in a flyback mode; and

a delay switch, configured to change into an on state from an off state when a trigger signal with a predetermined delay is received, so as to turn off the transistor;

and the ballast further comprising a half-bridge circuit, wherein the circuit for preheating filaments is connected with the half-bridge circuit in parallel.