Electronic ballast for lighting unit and lighting apparatus

1. An electronic ballast for a lighting unit, comprising:

a Power Factor Correction (PFC) circuit,

an inverter, and

a control circuit for controlling startup of the inverter,

wherein the control circuit is coupled between the PFC circuit and the inverter and comprises:

a switching device coupled in a startup loop for the inverter;

a unidirectional conductive device coupled between a PFC power supply circuit for providing an operation current to a PFC controller of the PFC circuit and an input of the PFC controller for preventing a startup current flowing through the PFC circuit from triggering the switching device; and

a triggering device coupled to the switching device and a connection point between the unidirectional conductive device and the PFC power supply circuit for controlling switch-on and switch-off of the switching device.

2. The electronic ballast according to claim 1 ,

wherein the switching device is further coupled in an oscillation loop for the inverter.

3. The electronic ballast according to claim 2 , further comprising:

first and second reservoir capacitors coupled between the PFC circuit and the inverter,

wherein the second reservoir capacitor functions as a voltage source of the startup loop and the oscillation loop for the inverter.

4. The electronic ballast according to claim 1 ,

wherein the PFC power supply circuit comprises a secondary winding of a boost transformer, a capacitor, a resistor, a diode and a voltage stabilizing diode.

5. The electronic ballast according to claim 1 ,

wherein the inverter is configured as a half-bridge form including first and second inverter switches, and a startup capacitor in the startup loop is charged by a startup current flowing through the startup loop for the inverter so as to provide a startup voltage for initially activating the second inverter switch.

6. The electronic ballast according to claim 1 ,

wherein the switching device comprises any one of a triac, a bipolar transistor and a field effect transistor.

7. The electronic ballast according to claim 1 ,

wherein the triggering device comprises a voltage stabilizing diode and a resistor which are connected in series or a capacitor.

8. The electronic ballast according to claim 1 ,

wherein the unidirectional conductive device comprises a diode or a thyristor.

9. A lighting apparatus, comprising:

an electronic ballast, comprising:

a Power Factor Correction (PFC) circuit,

an inverter, and

a control circuit for controlling startup of the inverter,

wherein the control circuit is coupled between the PFC circuit and the inverter and comprises:

a switching device coupled in a startup loop for the inverter;

a unidirectional conductive device coupled between a PFC power supply circuit for providing an operation current to a PFC controller of the PFC circuit and an input of the PFC controller for preventing a startup current flowing through the PFC circuit from triggering the switching device; and

a triggering device coupled to the switching device and a connection point between the unidirectional conductive device and the PFC power supply circuit for controlling switch-on and switch-off of the switching device;

a lighting unit which is driven by the electronic ballast to operate.

10. The lighting apparatus according to claim 9 ,

wherein the lighting unit is a gas discharge lamp.