Display device and method for improving image quality when driven at low-frequencies
A display device including: pixels coupled to first scan lines, second scan lines, emission control lines, and data lines; a first scan driver configured to supply a first scan signal to each of the first scan lines at a first frequency; a second scan driver configured to supply a second scan signal to each of the second scan lines at a second frequency corresponding to a driving frequency of the pixels; an emission driver configured to supply an emission control signal to each of the emission control lines at the first frequency; a data driver configured to supply a data signal to each of the data lines at the second frequency; and a timing controller configured to control the first scan driver, the second scan driver, the emission driver, and the data driver.
1. A display device, comprising:
pixels coupled to first scan lines, second scan lines, emission control lines, and data lines;
a first scan driver configured to supply a first scan signal to each of the first scan lines at a first frequency;
a second scan driver configured to supply a second scan signal to each of the second scan lines at a second frequency corresponding to a driving frequency of the to pixels;
an emission driver configured to supply an emission control signal to each of the emission control lines at the first frequency;
a data driver configured to supply a data signal to each of the data lines at the second frequency; and
is a timing controller configured to control the first scan driver, the second scan driver, the emission driver, and the data driver.
2. The display device according to claim 1 , wherein the first frequency is greater than the second frequency.
3. The display device according to claim 1 , wherein the second frequency is equal to the driving frequency and, wherein the second frequency and the driving frequency correspond to a submultiple of the first frequency.
4. The display device according to claim 1 , wherein the first scan driver supplies the first scan signal to each of the first scan lines at the first frequency that is two times a maximum driving frequency of the display device.
5. The display device according to claim 4 , wherein the emission driver supplies the emission control signal to each of the emission control lines at the first frequency that is two times the maximum driving frequency of the display device.
6. The display device according to claim 4 ,
wherein, when driven at the driving frequency, the second scan driver supplies the second scan signal during a first period of a frame period, and
wherein, when driven at the driving frequency, the second scan driver does not supply the second scan signal during a second period of the frame period.
7. The display device according to claim 6 , wherein, when driven at the maximum driving frequency of the display device, a length of the first period is equal to a length of the second period.
8. The display device according to claim 6 ,
wherein the first period includes a display scan period in which the first scan driver and the second scan driver supply the first and second scan signals so that the data signal is written to the pixels, and
wherein the second period includes a self-scan period in which characteristics of a driving transistor included in each of the pixels is changed by the supply of the first scan signal from the first scan driver.
9. The display device according to claim 8 , wherein, when the driving frequency is reduced, the number of self-scan periods included in the second period is increased.
10. The display device according to claim 1 , wherein a pixel disposed on an i-th (i is a natural number) horizontal line of the pixels comprises;
a light emitting element including a first electrode, and a second electrode coupled to a second power supply;
a first transistor including a first electrode coupled to a first node electrically connected to a first power supply, and configured to control a driving current based on a voltage of a second node;
a second transistor coupled between a data line of the data lines and the first node, and configured to be turned on by the first scan signal supplied to an i-th first scan line of the first scan lines;
a third transistor coupled between the second node and a third node coupled to a second electrode of the first transistor, and configured to be turned on by the second scan signal supplied to an i-th second scan line of the second scan lines;
a fourth transistor coupled between the second node and a first initialization power supply, and configured to be turned on by the second scan signal supplied to an i−1-th second scan line of the second scan lines;
a fifth transistor coupled between the first power supply and the first node, and configured to be turned off by the emission control signal supplied to an i-th emission control line of the emission control lines;
a sixth transistor coupled to the third node and the first electrode of the light emitting element, and configured to be turned off the emission control signal; and
a storage capacitor coupled between the first power supply and the second node.
11. The display device according to claim 10 ,
wherein the pixel disposed on the i-th horizontal line further comprises:
a seventh transistor coupled between the first electrode of the light emitting element and a second initialization power supply, and configured to be turned on by the first scan signal supplied to an i+1-th first scan line of the first scan lines, and
wherein a voltage of the first initialization power supply is different than a voltage of the second initialization power supply.
12. The display device according to claim 10 , wherein the pixel disposed on the i-th horizontal line further comprises:
a seventh transistor coupled between the first electrode of the light emitting element and the first initialization power supply, and configured to be turned on by the first scan signal supplied to an i+1-th first scan line of the first scan lines; and
an eighth transistor coupled between the first node and the first initialization power supply, and configured to be turned on by the second scan signal supplied to the i−1-th second scan line.
13. The display device according to claim 10 , wherein the pixel disposed on the i-th horizontal line further comprises:
a seventh transistor coupled between the first electrode of the light emitting element and the first initialization power supply, and configured to be turned on by the first scan signal supplied to an i+1-th first scan line of the first scan lines; and
an eighth transistor coupled between the third node and the first initialization power supply, and configured to be turned on by the second scan signal supplied to the i−1-th second scan line.
14. The display device according to claim 10 ,
wherein each of the first transistor, the second transistor, the fifth transistor, and the sixth transistor is a P-type transistor, and
wherein each of the third transistor and the fourth transistor is an N-type oxide semiconductor transistor.
15. The display device according to claim 14 ,
wherein the pixel disposed on the i-th horizontal line further comprises:
a seventh transistor coupled between the first electrode of the light emitting element and a second initialization power supply, and configured to be turned on by the second scan signal supplied to the i-th second scan line,
wherein the seventh transistor is the N-type oxide semiconductor transistor, and
wherein a voltage of the first initialization power supply is different than a voltage of the second initialization power supply.
16. The display device according to claim 14 ,
wherein the pixel disposed on the i-th horizontal line further comprises:
a seventh transistor coupled between the first electrode of the light emitting element and the second initialization power supply, and configured to be turned on by the emission control signal supplied to the i-th emission control line,
wherein the seventh transistor is the N-type oxide semiconductor transistor, and
wherein a voltage of the first initialization power supply is different than a voltage of the second initialization power supply.
17. The display device according to claim 1 , wherein a pixel disposed on an i-th (i is a natural number) horizontal line of the pixels comprises:
a light emitting element including a first electrode, and a second electrode coupled to a second power supply;
a first transistor including a first electrode coupled to a first node electrically connected to a first power supply, and configured to control a driving current based on a voltage of a second node;
a second transistor coupled between a first data line of the data lines and the first node, and configured to be turned on by the first scan signal supplied to an i-th first scan line of the first scan lines;
a third transistor coupled between the second node and a third node coupled to a second electrode of the first transistor, and configured to be turned on by the second scan signal supplied to an i-th second scan line of the second scan lines;
a fourth transistor coupled between the second node and a first initialization power supply, and configured to be turned on by a third scan signal supplied to an i-th third scan line; and
a fifth transistor coupled between the first power supply and the first node, and configured to be turned off by the emission control signal supplied to an i-th emission control line of the emission control lines.
18. The display device according to claim 17 , further comprising:
a third scan driver configured to supply a third scan signal to each of third scan lines coupled to the pixels at the second frequency, and
wherein widths of the second and the third scan signals are greater than a width of the first scan signal.
19. The display device according to claim 18 ,
wherein, when driven at the driving frequency, the second and the third scan drivers respectively supply the second and third scan signals during a first period of a frame period, and
wherein, when driven at the driving frequency, the second and the third scan drivers do not supply the second and third scan signals during a second period of the frame period.
20. The display device according to claim 19 , wherein, during the first period, the second scan signal supplied to the i-th second scan line does not overlap with the third scan signal supplied to the i-th third scan line.
21. The display device according to claim 19 , wherein, during the first period, the third scan signal supplied to the i-th third scan signal overlaps with a first portion of the second scan signal supplied to the i-th second scan line, and the first scan signal supplied to the i-th first scan line overlaps with a second portion of the second scan signal supplied to the i-th second scan line.
22. A display device, comprising:
pixels coupled to first scan lines, second scan lines, emission control lines, and data lines;
a first scan driver configured to supply a first scan signal to each of the first scan is lines at a first frequency;
a second scan driver configured to supply a second scan signal to each of the second scan lines at a second frequency, wherein the first frequency is greater than the second frequency;
an emission driver configured to supply an emission control signal to each of the emission control lines at the first frequency;
a data driver configured to supply a data signal to each of the data lines at the second frequency; and
a timing controller configured to control the second scan driver to supply the second scan signal during a first period of a frame period and not supply the second scan signal during a second period of the frame period.