Method of driving light source, light source module for performing the method and display apparatus having the light source module
View Patent ↗A method of driving a light source includes receiving an alternating current (“AC”) voltage from outside, generating a first direct current (“DC”) voltage based on the AC voltage, generating a second DC voltage, corresponding to a difference between a driving voltage of a light source part and the first DC voltage, based on the first DC voltage, and outputting a sum of the first DC voltage and the second DC voltage to the light source part.
1. A method of driving a light source, the method comprising:
receiving an alternating current (AC) voltage from outside;
generating a first direct current (DC) voltage based on the AC voltage;
generating a second DC voltage, corresponding to a difference between a driving voltage of a light source part and the first DC voltage, based on the first DC voltage; and
outputting a sum of the first DC voltage and the second DC voltage to the light source part,
wherein
the second DC voltage is generated using a DC/DC converter, and the DC/DC converter comprises:
a first input terminal which receives the first DC voltage;
a second input terminal which receives a ground voltage;
a first output terminal which outputs the sum of the first DC voltage and the second DC voltage; and
a second output terminal connected to the first input terminal.
2. The method of claim 1 , wherein the generating the first DC voltage comprises:
converting the AC voltage into a third DC voltage; and
converting the third DC voltage into the first DC voltage.
3. The method of claim 1 , wherein the DC/DC converter further comprises a transformer having a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are positioned at different sides in a circuit diagram.
4. The method of claim 1 , wherein the DC/DC converter further comprises a transformer having a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are positioned at a same side in a circuit diagram.
5. The method of claim 1 , wherein the generating the second DC voltage comprises:
detecting a voltage at a cathode electrode of the light source part; and
generating a control signal based on the voltage detected at the cathode electrode of the light source part.
6. A light source module comprising:
a light source part comprising a plurality of light emitting diodes;
a system power source part which receives an alternating current (AC) voltage from outside, and generates a first direct current (DC) voltage based on the AC voltage; and
a driving voltage generating part which generates a second DC voltage, corresponding to a difference between a driving voltage of the light source part and the first DC voltage, based on the first DC voltage, and outputs a sum of the first DC voltage and the second DC voltage to the light source part,
wherein the driving voltage generating part comprises a DC/DC converter, and
the DC/DC converter comprises:
a first input terminal which receives the first DC voltage;
a second input terminal which receives a ground voltage;
a first input terminal which outputs the sum of the first DC voltage and the second DC voltage; and
a second output terminal connected to the first input terminal.
7. The light source module of claim 6 , wherein the system power source part comprises:
an AC/DC converter which converts the AC voltage into a third DC voltage; and
a DC/DC converter which converts the third DC voltage into the first DC voltage.
8. The light source module of claim 6 , wherein the DC/DC converter further comprises a transformer including a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are positioned at different sides in a circuit diagram.
9. The light source module of claim 8 , wherein the DC/DC converter further comprises:
a switching element connected between the first coil and the second input terminal; and
a diode connected between the second coil and the first output terminal.
10. The light source module of claim 6 , wherein the DC/DC converter further comprises a transformer including a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are positioned at a same side in a circuit diagram.
11. The light source module of claim 10 , wherein the DC/DC converter further comprises:
a switching element connected between the first coil and the second input terminal;
a first diode connected between the second coil and a first node;
a second diode connected between the first node and the second output terminal; and
an inductor connected between the first node and the first output terminal.
12. The light source module of claim 6 , further comprising:
a voltage detecting part connected to a cathode electrode of the light source part, wherein the voltage detecting part detects a voltage at the cathode electrode of the light source part; and
a controlling part which generates a control signal for controlling the driving voltage generating part based on the voltage detected at the cathode electrode of the light source part.
13. A display apparatus comprising:
a display panel which displays an image; and
a light source module comprising:
a light source part which provides light to the display panel and having a plurality of light emitting diodes;
a system power source part which receives an alternating current (AC) voltage from outside, and generating a first direct current (DC) voltage based on the AC voltage; and
a driving voltage generating part which generates a second DC voltage, corresponding to a difference between a driving voltage of the light source part and the first DC voltage, based on the first DC voltage, and outputs a sum of the first DC voltage and the second DC voltage to the light source part,
wherein the driving voltage generating part comprises a DC/DC converter, and
the DC/DC converter comprises:
a first input terminal which receives the first DC voltage;
a second input terminal which receives a ground voltage;
a first input terminal which outputs the sum of the first DC voltage and the second DC voltage; and
a second output terminal connected to the first input terminal.
14. The display apparatus of claim 13 , wherein the DC/DC converter further comprises a transformer including a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are disposed in different sides in a circuit diagram.
15. The display apparatus of claim 13 , wherein the DC/DC converter further comprises a transformer including a first coil disposed at a primary side and a second coil disposed at a secondary side, and
a dot end of the first coil and a dot end of the second coil are disposed in a same side in a circuit diagram.
16. The display apparatus of claim 13 , wherein the light source part is disposed facing a lower surface of the display panel.
17. The display apparatus of claim 13 , wherein the light source module further comprises a light guide plate which guides light to the display panel, and
the light source part is disposed facing a side surface of the light guide plate.