Reference voltage generator, display device including the same, and method of driving display device
Provided is a display device which comprises a display panel including a plurality of pixels displaying an image based on a driving voltage, a reference voltage generator converting a sensing driving voltage generated by measuring the driving voltage into a sensing driving current, converting a preset reference driving voltage into a reference driving current, comparing the sensing driving current and the reference driving current, and generating a first reference voltage and a second reference voltage based on a difference between the sensing driving current and the reference driving current, a gamma voltage generator generating a plurality of gamma voltages by dividing the first reference voltage and the second reference voltage, and a data driver converting image data into a data voltage based on the gamma voltages and providing the data voltage to each of the pixels.
1. A display device, comprising:
a display panel including a plurality of pixels displaying an image based on a driving voltage;
a reference voltage generator converting a sensing driving voltage generated by measuring the driving voltage into a sensing driving current, converting a preset reference driving voltage into a reference driving current, comparing the sensing driving current and the reference driving current, and generating a first reference voltage and a second reference voltage based on a difference between the sensing driving current and the reference driving current;
a gamma voltage generator generating a plurality of gamma voltages by dividing the first reference voltage and the second reference voltage; and
a data driver converting image data into a data voltage based on the gamma voltages and providing the data voltage to each of the pixels.
2. The display device of claim 1 , wherein the reference voltage generator includes:
a first voltage-to-current converter converting the sensing driving voltage into the sensing driving current;
a second voltage-to-current converter converting the reference driving voltage into the reference driving current;
a current comparator comparing the sensing driving current and the reference driving current; and
a current-to-voltage converter generating the first reference voltage and the second reference voltage based on the difference between the sensing driving current and the reference driving current.
3. The display device of claim 2 , wherein the current-to-voltage converter includes:
a first current-to-voltage converter generating the first reference voltage based on a first initial reference voltage and the difference between the sensing driving current and the reference driving current; and
a second current-to-voltage converter generating the second reference voltage based on a second initial reference voltage and the difference between the sensing driving current and the reference driving current.
4. The display device of claim 3 , wherein the first current-to-voltage converter includes a first amplifier outputting the first reference voltage based on the first initial reference voltage and the difference between the sensing driving current and the reference driving current, and
wherein the second current-to-voltage converter includes a second amplifier outputting the second reference voltage based on the second initial reference voltage and the difference between the sensing driving current and the reference driving current.
5. The display device of claim 2 , wherein the first voltage-to-current converter includes:
a first amplifier having a first input terminal to which the sensing driving voltage is applied;
a first resistor connected to a second input terminal of the first amplifier and through which the sensing driving current flows; and
a first transistor series-connected to the first resistor and having a gate electrode connected to an output terminal of the first amplifier, and
wherein the second voltage-to-current converter includes:
a second amplifier having a first input terminal to which the reference driving voltage is applied;
a second resistor connected to a second input terminal of the second amplifier and through which the reference driving current flows; and
a second transistor series-connected to the second resistor and having a gate electrode connected to an output terminal of the second amplifier.
6. The display device of claim 2 , wherein the current comparator includes:
a first transistor through which the sensing driving current flows; and
a second transistor series-connected to the first transistor and through which the reference driving current flows.
7. The display device of claim 6 , wherein the first transistor is an N-type metal oxide semiconductor (“NMOS”) transistor, and
wherein the second transistor is a P-type metal oxide semiconductor (“PMOS”) transistor.
8. The display device of claim 2 , wherein the reference voltage generator further includes:
a current minor block transmitting the sensing driving current generated from the first voltage-to-current converter and the reference driving current generated from the second voltage-to-current converter to the current comparator.
9. The display device of claim 2 , wherein the reference voltage generator further includes:
a first current clamp limiting a range of the sensing driving current; and
a second current clamp limiting a range of the reference driving current.
10. The display device of claim 1 , further comprising:
a timing controller controlling a driving of the data driver and providing the reference driving current to the reference voltage generator.
11. The display device of claim 1 , wherein the reference driving voltage is a target driving voltage in driving the pixels normally.
12. The display device of claim 1 , further comprising:
a power supply providing the driving voltage to the pixels and providing a first initial reference voltage for generating the first reference voltage and a second initial reference voltage in order to generate the second reference voltage to the reference voltage generator.
13. A reference voltage generator, comprising:
a first voltage-to-current converter converting a sensing driving voltage generated by measuring a driving voltage provided to pixels into a sensing driving current;
a second voltage-to-current converter converting a preset reference driving voltage into a reference driving current;
a current comparator comparing the sensing driving current and the reference driving current; and
a current-to-voltage converter generating a first reference voltage and a second reference voltage based on a difference between the sensing driving current and the reference driving current.
14. The reference voltage generator of claim 13 , wherein the current-to-voltage converter includes:
a first current-to-voltage converter generating the first reference voltage based on a first initial reference voltage and the difference between the sensing driving current and the reference driving current; and
a second current-to-voltage converter generating the second reference voltage based on a second initial reference voltage and the difference between the sensing driving current and the reference driving current.
15. The reference voltage generator of claim 14 , wherein the first current-to-voltage converter includes a first amplifier outputting the first reference voltage based on the first initial reference voltage and the difference between the sensing driving current and the reference driving current, and
wherein the second current-to-voltage converter includes a second amplifier outputting the second reference voltage based on the second initial reference voltage and the difference between the sensing driving current and the reference driving current.
16. The reference voltage generator of claim 13 , wherein the current comparator includes:
a first transistor through which the sensing driving current flows; and
a second transistor series-connected to the first transistor and through which the reference driving current flows.
17. The reference voltage generator of claim 16 , wherein the first transistor is an NMOS transistor, and
wherein the second transistor is a PMOS transistor.
18. The reference voltage generator of claim 13 , further comprising:
a current minor block transmitting the sensing driving current generated from the first voltage-to-current converter and the reference driving current generated from the second voltage-to-current converter to the current comparator.
19. A method of driving a display device, the method comprising steps of:
generating a sensing driving voltage by measuring a driving voltage provided to a plurality of pixels;
converting the sensing driving voltage into a sensing driving current;
converting a preset reference driving voltage into a reference driving current;
comparing the sensing driving current and the reference driving current;
generating a first reference voltage and a second reference voltage based on a difference between the sensing driving current and the reference driving current; and
generating a plurality of gamma voltages by dividing the first reference voltage and the second reference voltage.
20. The method of claim 19 , wherein generating the first reference voltage and the second reference voltage is accomplished by
generating the first reference voltage based on a first initial reference voltage and the difference between the sensing driving current and the reference driving current, and
generating the second reference voltage based on a second initial reference voltage and the difference between the sensing driving current and the reference driving current.