T5 lamp end of life protection circuit

Patent metadata

Field	Value
Publication number	US-2016165705-A1
Application number	US-201314907644-A
Country	US
Kind code	A1
Filing date	Jul 30, 2013
Priority date	Jul 30, 2013
Publication date	Jun 9, 2016
Grant date	—

Abstract

Provided are an end-of-life protection circuit for a non-isolated electronic ballast and a method for protecting same. The non-isolated electronic ballast includes a driver circuit ( 104 ), a sampling circuit ( 108 ), and a control circuit ( 102 ). The driver circuit ( 104 ) connects to an output circuit ( 106 ) for controlling operation of a load. The sampling circuit ( 108 ) samples direct current (DC) voltage values of a capacitor of a lamp coupled to the ballast to detect occurrence of an asymmetric event. The control circuit ( 102 ) receives a voltage value in response to detecting the asymmetric event and outputs to the driver circuit ( 104 ) a control signal to control operation of the driver circuit ( 104 ) to prevent end-of-life damage. Provided also are an end-of-life protection circuit for an isolated electronic ballast and a method for protecting same.

First claim

We claim:

1 . An end-of-life protection circuit for a non-isolated electronic ballast, comprising:
a driver circuit connected to an output circuit for controlling operation of a load; a sampling circuit configured to sample direct current (DC) voltage values of a capacitor of a lamp coupled to the ballast to detect the occurrence of an asymmetric event; and a control circuit for receiving a voltage value in response to the detection of the asymmetric event from the sampling circuit and for outputting to the driver circuit a control signal to control operation of the driver to prevent end of life damage.

2 . The circuit of claim 1 , wherein the DC voltage value is changed upon detecting the asymmetric event.

3 . The circuit of claim 1 , wherein driver circuit comprises a half bridge driver circuit including a DC voltage, a half bridge control, a power supply for the half bridge and driver MOSFETs, wherein the half bridge driver is configured to set a frequency output for the output circuit and provide end of life protection for the lamp.

4 . The circuit of claim 3 , wherein the driver circuit triggers the half bridge driver to change a half bridge control, shut down the half bridge or output a high frequency when the asymmetric event is detected.

5 . The circuit of claim 1 , wherein the output circuit comprises a limit inductor, an oscillation capacitor and a lamp load.

6 . The circuit of claim 1 , wherein the sampling circuit comprises a half bridge capacitor, a pair of resistors, and an end of life sensor capacitor.

7 . A method for providing end-of-life protection for a non-isolated electronic ballast configure for coupling a lamp thereto, comprising:
sampling direct current (DC) voltage values of a capacitor of the lamp to detect occurrence of an asymmetric event in the ballast; receiving, as input to a control circuit, a voltage value in response to detecting the asymmetric event; and outputting, from the control circuit, to a driver circuit, a control signal to control operation of the driver circuit to prevent end of life damage.

8 . The method of claim 7 , further comprising changing the DC voltage value upon detecting the asymmetric event.

9 . The method of claim 7 , wherein the driver circuit comprises a half bridge driver circuit including a DC voltage, a half bridge control, a power supply for the half bridge driver and driver MOSFETs, wherein the half bridge driver is configured to set a frequency output for the output circuit and provide the end of life protection for the lamp.

10 . The method of claim 9 , further comprising triggering the half bridge driver to change a half bridge control, shut down the half bridge or output a high frequency when the asymmetric event is detected.

11 . The method of claim 7 , wherein outputting, from the control circuit, to a driver circuit further comprises proving an output circuit including a limit inductor, an oscillation capacitor and a lamp load.

12 . The method of claim 7 , wherein sampling the DC voltage values further comprises providing a sampling circuit including a half bride capacitor, a pair of resistors, and an end of life sensor capacitor.

13 . An end-of-life protection circuit for an isolated electronic ballast, comprising:
a driver circuit connected to an output circuit for controlling operation of a load; and a detect and control circuit for monitoring direct current (DC) voltage values of a capacitor of lamp to detect the occurrence of an asymmetric event and for outputting to the driver circuit a control signal to control the operation of the driver to prevent end of life damage.

14 . The circuit of claim 13 , wherein the DC voltage value is changed upon detecting the asymmetric event.

15 . The circuit of claim 13 , wherein driver circuit comprises a half bridge driver circuit including a DC voltage, a pair of electrolytic capacitors, a limit transformer, an oscillation capacitor, a half bridge power bipolar junction transistor (BJT), and a pair of resistors.

16 . The circuit of claim 15 , wherein the half bridge power BJT shuts down such that the half bridge driver stops operating when the asymmetric event is detected.

17 . The circuit of claim 15 , wherein the output circuit comprises an oscillation capacitor, an output transformer, and a lamp load.

18 . A method for providing end-of-life protection for an isolated electronic ballast including a driver circuit, the electronic ballast being configured for coupling to a lamp, the method comprising:
monitoring direct current (DC) voltage values of a capacitor coupled to the lamp to detect occurrence of an asymmetric event; and outputting to the driver circuit a control signal to control operation of the driver circuit to prevent end of life damage.

19 . The method of claim 18 , further comprising changing the DC voltage value upon the detection of the asymmetric event.

20 . The method of claim 18 , further comprising shutting down the half bridge power BJT such that the half bridge driver stops operating when the asymmetric event is detected.

Assignees

• Zhang Bo
• Mao Zhu
• Gen Electric

Inventors

• Zhang Bo
• Mao Zhu

Classifications

• H05B41/2985 Primary

  against abnormal lamp operating conditions · CPC title