Power supply device and projection apparatus using the same

1. A power supply device, comprising:

a filter, for receiving a pulse width modulation signal and accordingly outputting a first direct-current voltage; and

voltage driving unit, coupled to the filter, the voltage driving unit comprising:

a voltage-regulation feedback unit, for receiving the first direct-current voltage and accordingly outputting a second direct-current voltage; and

current amplification component, coupled to the voltage-regulation feedback unit for receiving an operational voltage and the second direct-current voltage, performing a current amplification operation on the second direct-current voltage, and accordingly outputting a driving voltage, wherein the driving voltage is fed back to the voltage-regulation feedback unit; wherein the voltage-regulation feedback unit regulates the driving voltage fed back to the voltage-regulation feedback unit according to the first direct-current voltage; and

wherein the current amplification component is a first pnp-type bipolar junction transistor and the power supply device further comprises a protection device coupled to the current amplification component, the protection device comprises a resistance component and a second pnp-type bipolar junction transistor, the resistance component is coupled between the operational voltage and an emitter of the first pnp-type bipolar junction transistor, the second pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a base coupled to the emitter of the first pnp-type bipolar junction transistor, and a collector coupled to a base of the first pnp-type bipolar junction transistor, and a collector of the first pnp-type bipolar junction transistor outputs the driving voltage;

wherein when a large current flows into the resistance component via the current amplification component, the second pnp-type bipolar junction transistor enters a saturation region to turn on for the first pnp-type bipolar junction transistor entering a cut-off region to turn off.

2. The power supply device according to claim 1 , wherein the filter is a resistor-capacitor filter or inductor-capacitor filter.

3. The power supply device according to claim 1 , wherein the driving voltage regulated by the voltage-regulation feedback unit is substantially equal to the first direct-current voltage.

4. The power supply device according to claim 3 , wherein the voltage-regulation feedback unit is implemented by using an operation amplifier.

5. The power supply device according to claim 4 , wherein a non-inverse input terminal and an inverse input terminal of the operation amplifier are respectively coupled to the driving voltage and the first direct-current voltage.

6. The power supply device according to claim 1 , wherein the current amplification component is a first pnp-type bipolar junction transistor, and the first pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a collector for outputting the driving voltage and a base coupled to the second direct-current voltage;

wherein the voltage-regulation feedback unit outputs the second direct-current voltage to turn on the first pnp-type bipolar junction transistor for the first pnp-type bipolar junction transistor outputting the driving voltage according to the operational voltage.

7. The power supply device according to claim 1 , wherein the driving voltage is for driving at least a fan of a projection apparatus.

8. A projection apparatus, comprising: a projection control unit, for generating an image beam;

a power supply device, coupled to the projection control unit, comprising:

a filter, for receiving a pulse width modulation signal and accordingly outputting a first direct-current voltage; and

voltage driving unit, coupled to the filter, the voltage driving unit comprising:

a voltage-regulation feedback unit, for receiving the first direct-current voltage and accordingly outputting a second direct-current voltage; and

current amplification component, coupled to the voltage-regulation feedback unit for receiving an operational voltage and the second direct-current voltage, performing a current amplification operation on the second direct-current voltage, and accordingly outputting a driving voltage, wherein the driving voltage is fed back to the voltage-regulation feedback unit; and

fan, for receiving the driving voltage and accordingly releasing heat of the projection control unit;

wherein the voltage-regulation feedback unit regulates the driving voltage fed back to the voltage-regulation feedback unit according to the first direct-current voltage; and

wherein the current amplification component is a first pnp-type bipolar junction transistor and the power supply device further comprises a protection device coupled to the current amplification component, the protection device comprises a resistance component and a second pnp-type bipolar junction transistor, the resistance component is coupled between the operational voltage and an emitter of the first pnp-type bipolar junction transistor, the second pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a base coupled to the emitter of the first pnp-type bipolar junction transistor, and a collector coupled to a base of the first pnp-type bipolar junction transistor, and a collector of the first pnp-type bipolar junction transistor outputs the driving voltage;

wherein when a lame current flows into the resistance component via the current amplification component, the second pnp-type bipolar junction transistor enters a saturation region to turn on for the first pnp-type bipolar junction transistor entering a cut-off region to turn off.

9. The projection apparatus according to claim 8 , wherein the filter is a resistor-capacitor filter or inductor-capacitor filter.

10. The projection apparatus according to claim 8 , wherein the driving voltage regulated by the voltage-regulation feedback unit is substantially equal to the first direct-current voltage.

11. The projection apparatus according to claim 10 , wherein the voltage-regulation feedback unit is implemented by using an operation amplifier.

12. The projection apparatus according to claim 11 , wherein a non-inverse input terminal and an inverse input terminal of the operation amplifier are respectively coupled to the driving voltage and the first direct-current voltage.

13. The projection apparatus according to claim 8 , wherein the current amplification component is a first pnp-type bipolar junction transistor, and the first pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a collector for outputting the driving voltage and a base coupled to the second direct-current voltage;

wherein the voltage-regulation feedback unit outputs the second direct-current voltage to turn on the first pnp-type bipolar junction transistor for the first pnp-type bipolar junction transistor outputting the driving voltage according to the operational voltage.

14. A projection apparatus, comprising:

a projection control unit, for generating an image beam;

a power supply device, coupled to the projection control unit, comprising:

a filter, for receiving a pulse width modulation signal and accordingly outputting a first direct-current voltage; and

voltage driving unit, coupled to the filter for receiving an operational voltage, wherein the voltage driving unit is for performing a current amplification operation and accordingly outputting a driving voltage; and

protection device, coupled to the voltage driving unit, wherein when a large current flows into the protection device via the voltage driving unit, the protection device disables the voltage driving unit; and fan, for receiving the driving voltage and accordingly releasing heat of the projection control unit; and

wherein the voltage driving unit comprises a first pnp-type bipolar junction transistor, a collector of the first pnp-type bipolar junction transistor outputs the driving voltage, a base of the first pnp-type bipolar junction transistor is coupled to the filter, the protection device comprises a resistance component and a second pnp-type bipolar junction transistor, the resistance component is coupled between the operational voltage and an emitter of the first pnp-type bipolar junction transistor, the second pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a base coupled to the emitter of the first pnp-type bipolar junction transistor, and a collector coupled to a base of the first pnp-type bipolar junction transistor;

wherein when the large current flows into the resistance component via the first pnp-type bipolar junction transistor, the second pnp-type bipolar junction transistor enters a saturation region to turn on such that the first pnp-type bipolar junction transistor entering a cut-off region to turn off.

15. The projection apparatus according to claim 14 , wherein the filter is a resistor-capacitor filter or inductor-capacitor filter.

16. The projection apparatus according to claim 14 , wherein the voltage driving unit comprises a voltage-regulation feedback unit and a current amplification component, the voltage-regulation feedback unit is coupled to the filter, the driving voltage is fed back to the voltage-regulation feedback unit, the voltage-regulation feedback unit regulates the driving voltage fed back to the voltage-regulation feedback unit according to the first direct-current voltage and accordingly outputs a second direct-current voltage, the current amplification component is coupled to the voltage-regulation feedback unit and the protection device and the current amplification component performs a current amplification operation on the second direct-current voltage and accordingly outputs the driving voltage.