Multi-output electronic ballast

Patent metadata

Field	Value
Publication number	US-9426869-B2
Application number	US-201113231337-A
Country	US
Kind code	B2
Filing date	Sep 13, 2011
Priority date	Mar 28, 2011
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

A multi-output electronic ballast is disclosed. The multi-output electronic ballast is used to drive a plurality of lamp assemblies and includes an AC/DC converter, a first inverter, a second inverter, an auxiliary voltage generator, and a control circuit. The AC/DC converter converts an AC input voltage to a high DC voltage. The first inverter converts the high DC input voltage to a first AC voltage selectively. The second inverter converts the high DC voltage to a second AC voltage. The auxiliary voltage generator generates an auxiliary voltage. The control circuit receives the auxiliary voltage generating circuit and outputs a control signal to the first inverter according to the switching operation of a first external switch. When the control signal is transmitted to the first inverter, the first inverter comes into operation and converts the high DC voltage to the first AC voltage.

First claim

What is claimed is:

1. A multi-output electronic ballast for driving a plurality of lamp assemblies, comprising:
an AC/DC converter coupled to an AC power supply to receive an AC input voltage and configured to output a high DC voltage to a DC bus;
a first inverter configured to receive the high DC voltage from the DC bus and to output a high-frequency first AC voltage for driving a first lamp assembly;
a second inverter configured to receive the high DC voltage from the DC bus and to output a high-frequency second AC voltage for driving a second lamp assembly;
an auxiliary voltage generator configured to generate an auxiliary DC voltage; and
a control circuit coupled to the AC power supply and configured to output a control DC voltage for controlling the operation of the first inverter based on a state of a first switch, the first switch being connected in series between the control circuit and the AC power supply, wherein the control circuit generates the control DC voltage from one of the high DC voltage from the DC bus or the auxiliary DC voltage when the first switch is closed and does not generate the control DC voltage when the first switch is open.

2. The multi-output electronic ballast according to claim 1 wherein the control circuit includes:
a first switch element having a current input terminal connected to the auxiliary voltage generator, an output terminal over which the control DC voltage is supplied to the first inverter via a first resistor, and a control terminal coupled to the first switch via a detector.

3. The multi-output electronic ballast according to claim 2 wherein the detector includes:
a second resistor connected to the control terminal of the first switch element;
a voltage dividing and rectifying circuit connected to the first switch for dividing and rectifying the AC input voltage and generating a first DC voltage accordingly;
a first capacitor connected to the voltage dividing and rectifying circuit;
a first zener diode connected to the first capacitor and the voltage dividing and rectifying circuit for determining if the level of the first DC voltage is larger than a threshold level;
a first voltage divider connected to the first zener diode for dividing the first DC voltage and generating a second DC voltage accordingly; and
a second switch element having a control terminal connected to the first voltage divider and a current input terminal connected to the second resistor.

4. The multi-output electronic ballast according to claim 3 wherein the voltage dividing and rectifying circuit includes:
a third resistor;
a fourth resistor; and
a first diode;
wherein the third resistor and the first diode are connected in series with the first switch.

5. The multi-output electronic ballast according to claim 3 wherein the first voltage divider includes:
a fifth resistor connected between the first zener diode and the control terminal of the second switch element; and
a sixth resistor connected to the fifth resistor and the control terminal of the second switch element.

6. The multi-output electronic ballast according to claim 2 wherein the control circuit further includes a second zener diode connected to the current input terminal of the first switch element for preventing a level of the control DC voltage from being excessive.

7. The multi-output electronic ballast according to claim 2 wherein the control circuit further includes a second capacitor connected to the current input terminal of the first switch element for retaining energy required for generating the control DC voltage.

8. The multi-output electronic ballast according to claim 2 wherein the control circuit further includes a seventh resistor connected to the current input terminal of the first switch element and the AC/DC converter, such that the high DC voltage is supplied to the control circuit via the seventh resistor.

9. The multi-output electronic ballast according to claim 2 wherein the control circuit further includes an eighth resistor connected to the current input terminal of the first switch element and the control terminal of the first switch element for preventing faulty operations of the first switch element.

10. The multi-output electronic ballast according to claim 1 wherein the first inverter includes:
a first switch circuit connected to the AC/DC converter for receiving the high DC voltage;
a second voltage divider connected to the AC/DC converter for receiving the high DC voltage and for generating a fractional voltage from the high DC voltage;
a first resonant circuit connected to the first switch circuit; and
a first inverter controller connected to the first switch circuit and the control circuit, the first inverter controller configured to receive the control DC voltage from the control circuit and control operation of the first switch circuit based on the control DC voltage.

11. The multi-output electronic ballast according to claim 10 wherein the first inverter further includes a first protection circuit connected to the second voltage divider for preventing a level of the fractional voltage from being excessive.

12. The multi-output electronic ballast according to claim 10 wherein the first inverter further includes a first pre-heating circuit for pre-heating the first lamp assembly.

13. The multi-output electronic ballast according to claim 1 wherein the AC/DC converter includes:
an electromagnetic interface filter connected to the first switch;
a rectifier connected to the electromagnetic interface filter; and
a power factor correction circuit connected to the rectifier and configured to output the high DC voltage, the power factor correction circuit comprising a power factor correction controller, an inductor, a diode, a resistor, and a switch element.

Assignees

• Chou Ching-Ho
• Lu Yung-Chuan
• Delta Electronics Inc

Inventors

• Chou Ching-Ho
• Lu Yung-Chuan

Classifications

• H05B41/295

  with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps · CPC title

• H05B41/28 Primary

  using static converters · CPC title