Apparatus for supplying power and liquid crystal display having the same
View Patent ↗Disclosed are a power supplying apparatus and a LCD having the same that reduces manufacturing cost of a large-scale LCD module and enhances powpower efficiency by integrating an external dc power supply used in a large-scale LCD panel into a LCD panel. A first voltage converter converts an external ac voltage into a first dc voltage, and changes a voltage level of the first de voltage into a second dc voltage having a highr voltage level than that of the first de voltage. A second voltage converter converts the second dc voltage into an ac voltage, raises a voltage level of the converted ac voltage, and provides the raised ac voltage to a load. A current detector detects a current flowing through the load, and provides a current detection signal as a feedback signal to the first voltage converter so that the first voltage provide a constant direct current output voltage.
1. A power supplying apparatus, comprising:
a first voltage converting means for converting a first alternating current voltage into a first direct current voltage, and for changing a voltage level of the first direct current voltage into a second direct current voltage having a higher voltage level than the voltage level of the first direct current voltage;
a second voltage converting means for converting the second direct current voltage into a second alternating current voltage, and for changing a voltage level of the second alternating current voltage into a third alternating current voltage having a higher voltage level than the voltage level of the second alternating current voltage to provide the third alternating current voltage to a first load; and
a current detector for detecting a current flowing through the first load, and for providing a current detecting signal to the first voltage converting means so that the first voltage converting means provides a constant direct current output voltage,
wherein the power supplying apparatus includes an AC input section and a liquid crystal display (LCD) module section,
wherein the first voltage converting means and the second voltage converting means are formed in the LCD module section,
wherein the second voltage converting means comprises:
a transformer including a primary coil and a secondary coil, the primary coil of the transformer being connected to an output terminal of the first voltage converting means, and the secondary coil of the transformer being connected the first load;
a resonance capacitor, connected in parallel with the primary coil, for forming an LC resonance circuit;
a first transistor, a base of the first transistor being connected to the output terminal of the first voltage converting means, a collector of the first transistor being connected to a first end of the resonance capacitor, and an emitter of the first transistor being connected to a ground, for driving the transformer;
a second transistor, a base of the second transistor being connected to the output terminal of the first voltage converting means, a collector of the second transistor being connected to a second end of the resonance capacitor, and an emitter of the second transistor being connected to the ground, for driving the transformer.
2. A power supplying apparatus, comprising:
a first voltage converting means for converting a first alternating current voltage into a first direct current voltage, and for changing a voltage level of the first direct current voltage into a second direct current voltage having a higher voltage level than the voltage level of the first direct current voltage;
a second voltage converting means for converting the second direct current voltage into a second alternating current voltage, and for changing a voltage level of the second alternating current voltage into a third alternating current voltage having a higher voltage level than the voltage level of the second alternating current voltage to provide the third alternating current voltage to a first load; and
a current detector for detecting a current flowing through the first load, and for providing a current detecting signal to the first voltage converting means so that the first voltage converting means provides a constant direct current output voltage,
wherein the second voltage converting means comprises:
a transformer including a primary coil and a secondary coil, the primary coil of the transformer being connected to an output terminal of the first voltage converting means, and the secondary coil of the transformer being connected the first load;
a resonance capacitor, connected in parallel with the primary coil, for forming an LC resonance circuit;
a first transistor, a base of the first transistor being connected to the output terminal of the first voltage converting means, a collector of the first transistor being connected to a first end of the resonance capacitor, and an emitter of the first transistor being connected to a ground, for driving the transformer;
a second transistor, a base of the second transistor being connected to the output terminal of the first voltage converting means, a collector of the second transistor being connected to a second end of the resonance capacitor, and an emitter of the second transistor being connected to the ground, for driving the transformer.
3. The power supplying apparatus of claim 2 , wherein the first voltage converting means comprises:
a rectifying means for rectifying the first alternating current voltage into the first direct current voltage; and
a dc-to-dc converter for converting the first direct current voltage into the second direct current voltage to provide the second direct current voltage to the second voltage converting means,
wherein said dc-to-dc converter varies the voltage level of the second direct current voltage in response to the detected current signal.
4. The power supplying apparatus of claim 2 , wherein the second voltage converting means is a royer inverter, a push-pull Inverter, a half bridge Inverter or a full-bridge Inverter.
5. The power supplying apparatus of claim 2 , wherein the second voltage converting means further comprises a first resistor, a first end of the first resistor being connected to the base of the first transistor, and a second end of the first resistor being connected to the output terminal of the first voltage converting means.
6. The power supplying apparatus of claim 2 , wherein the second voltage converting means further comprises a second resistor, a first end of the second resistor being connected to the base of the second transistor, and a second end of the second resistor being connected to the output terminal of the first voltage converting means.
7. The power supplying apparatus of claim 2 , wherein the first alternating current voltage is a commercial alternating current voltage, and the second direct current voltage has a voltage level between about 150 volts and about 200 volts.
8. The power supplying apparatus of claim 2 , wherein the first voltage converting means further generates a third direct current voltage having a voltage level lower than the voltage level of the first direct current voltage and provides the third direct current voltage to a second load, by receiving the first alternating current voltage.
9. The power supplying apparatus of claim 8 , further comprising a third voltage converting means for providing the third direct current voltage to the second load.