Drive voltage generating circuit and liquid crystal display including the same
A drive voltage generating circuit which has a first shifter receiving an input voltage and outputting a first drive voltage obtained by first shifting a voltage level of the input voltage; a second shifter receiving outputting the second drive voltage obtained by second shifting a voltage level of the first drive voltage; and a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature, wherein the second drive voltage is continuously varied in an analog manner, in accordance with the surrounding temperature.
1. A drive voltage generating circuit comprising:
a first shifter receiving an input voltage, first shifting a voltage level of the input voltage, and outputting a first drive voltage;
a second shifter second shifting a voltage level of the first drive voltage and outputting a second drive voltage; and
a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature,
wherein the second drive voltage is continuously varied in relation to changes in the surrounding temperature, wherein a voltage level of the second drive voltage is substantially in an inverse proportion to a change of the surrounding temperature, and wherein the second drive voltage has a first voltage level in a first region where the surrounding temperature is high, a second voltage level that is higher than the first voltage level in a second region where the surrounding temperature is low, and a voltage level that continuously increases from the first voltage level to the second voltage level in accordance with the temperature decrease in a third region between the first region and the second region.
2. The drive voltage generating circuit of claim 1 , wherein the second drive voltage is a gate-on voltage.
3. The drive voltage generating circuit of claim 1 , wherein the first shifter, the second shifter, and the drive voltage controller are formed on a single chip.
4. The drive voltage generating circuit of claim 1 , wherein the drive voltage generating circuit is a buck converter or a boost converter.
5. The drive voltage generating circuit of claim 1 , wherein the drive voltage controller comprises a reference voltage generator including a variable element and outputting a reference voltage that is varied in accordance with the surrounding temperature, and adjusting the second drive voltage level corresponding to a result of comparing a first feedback voltage that corresponds to the second drive voltage level with the reference voltage.
6. The drive voltage generating circuit of claim 5 , wherein the second drive voltage level is substantially in direct proportion to a change of a voltage level of the reference voltage.
7. The drive voltage generating circuit of claim 5 , wherein the resistance value of the variable element is substantially in an inverse proportion to a change of the surrounding temperature.
8. The drive voltage generating circuit of claim 5 , wherein one of the first shifter and the second shifter comprises a switching element, the drive voltage controller further comprises a comparator comparing the first feedback voltage with the reference voltage, and the drive voltage controller turns on/off the switching element based on a result of comparing a second feedback voltage that is in proportion to a current flowing through the switching element with an output of the comparator.
9. The drive voltage generating circuit of claim 5 , wherein the reference voltage generator receives a first DC voltage, a variable voltage having a voltage level that is varied in accordance with the resistance value of the variable element, and a second DC voltage that is lower than the first DC voltage, compares the voltage level of the variable voltage with a voltage level of the first DC voltage or a voltage level of the second DC voltage, and selects and outputs any one of the first DC voltage, the variable voltage, and the second DC voltage as the reference voltage.
10. A drive voltage generating circuit, comprising:
a first shifter receiving an input voltage, first shifting a voltage level of the input voltage, and outputting a first drive voltage;
a second shifter second shifting a voltage level of the first drive voltage and outputting a second drive voltage; and
a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature,
wherein the second drive voltage is continuously varied in relation to changes in the surrounding temperature, wherein the drive voltage controller comprises a reference voltage generator including a variable element and outputting a reference voltage that is varied in accordance with the surrounding temperature, and adjusting the second drive voltage level corresponding to a result of comparing a first feedback voltage that corresponds to the second drive voltage level with the reference voltage, and wherein the second drive voltage is a gate-off voltage, and wherein the gate-off voltage has a first voltage level in a first region where the surrounding temperature is high, a second voltage level that is higher than the first voltage level in a second region where the surrounding temperature is low, and a voltage level that continuously decreases from the first voltage level to the second voltage level in accordance with the temperature decrease in a third region between the first region and the second region.
11. A liquid crystal display comprising:
a drive voltage generating circuit including;
a first shifter receiving an input voltage, first shifting a voltage level of the input voltage, and outputting a first drive voltage,
a second shifter second shifting a voltage level of the first drive voltage and outputting a second drive voltage, and
a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature, wherein the second drive voltage is continuously varied in relation to changes in the surrounding temperature;
a gate driver outputting a gate signal generated by using the second drive voltage; and
a plurality of pixels being turned on/off in accordance with the gate signal from the gate driver, wherein the second drive voltage is a gate-on voltage or a gate-off voltage, and wherein a voltage level of the gate-off voltage is substantially in an inverse proportion to a change of the surrounding temperature, and wherein the voltage level of the gate-off voltage has a first voltage level in a first region where the surrounding temperature is high, a second voltage level that is higher than the first voltage level in a second region where the surrounding temperature is low, and a voltage level that continuously decreases from the first voltage level to the second voltage level in accordance with the temperature decrease in a third region between the first region and the second region.
12. The liquid crystal display of claim 11 , wherein a voltage level of the second drive voltage is substantially in an inverse proportion to a change of the surrounding temperature.
13. The liquid crystal display of claim 11 , wherein the drive voltage controller comprises a reference voltage generator including a variable element and outputting a reference voltage that is varied in accordance with the surrounding temperature, and adjusting the second drive voltage level corresponding to a result of comparing a first feedback voltage that corresponds to the second drive voltage level with the reference voltage.
14. The liquid crystal display of claim 11 , further comprising a clock generator receiving the second drive voltage and outputting a first clock signal and a second clock signal, wherein the gate signal is generated by using the first clock signal and the second clock signal.
15. The liquid crystal display of claim 11 , wherein the gate driver generates the gate signal using amorphous silicon thin film transistors.
16. A liquid crystal display, comprising:
a drive voltage generating circuit including;
a first shifter receiving an input voltage, first shifting a voltage level of the input voltage, and outputting a first drive voltage,
a second shifter second shifting a voltage level of the first drive voltage and outputting a second drive voltage, and
a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature, wherein the second drive voltage is continuously varied in relation to changes in the surrounding temperature;
a gate driver outputting a gate signal generated by using the second drive voltage; and
a plurality of pixels being turned on/off in accordance with the gate signal from the gate driver, wherein the second drive voltage is a gate-on voltage or a gate-off voltage, wherein a voltage level of the second drive voltage is substantially in an inverse proportion to a change of the surrounding temperature, and wherein the second drive voltage has a first voltage level in a first region where the surrounding temperature is high, a second voltage level that is higher than the first voltage level in a second region where the surrounding temperature is low, and a voltage level that continuously increases from the first voltage level to the second voltage level in accordance with the temperature decrease in a third region between the first region and the second region.