Frequency variable display apparatus and flicker compensation method thereof

1 . A display apparatus comprising:

a display panel including a plurality of subpixels;

an image driving circuit configured to write, in each of the plurality of subpixels, a data voltage through a data line and a reference voltage through a reference voltage line during a vertical active period of one frame to implement active luminance; and

a flicker compensation circuit configured to apply a compensation voltage to at least one of the data line and the reference voltage line in a vertical blank period of the one frame to implement blank luminance, the blank luminance being lower than the active luminance,

wherein the vertical blank period includes a vertical front porch period between an end of the vertical active period of the one frame and a start of a vertical synchronization signal, and

wherein the flicker compensation circuit is further configured to apply the compensation voltage to the data line during the vertical front porch period of the one frame.

2 . The display apparatus of claim 1 , wherein the vertical blank period includes a vertical back porch period before the vertical active period in the one frame,

wherein a length of the vertical back porch period is fixed to a constant value regardless of a length variation of the one frame, and

wherein a length of the vertical front porch period varies in proportion to a length of the one frame.

3 . The display apparatus of claim 2 , wherein the flicker compensation circuit is further configured to apply the compensation voltage to the reference voltage line in the vertical front porch of the one frame.

4 . The display apparatus of claim 1 , wherein an electric potential of the data line in the vertical active period is the data voltage,

wherein the electric potential of the data line in the vertical front porch period is changed from the data voltage to a first compensation voltage that is lower than the data voltage, and

wherein a gate-source voltage of a driving transistor included in each subpixel is lower in the vertical front porch period than in the vertical active period.

5 . The display apparatus of claim 4 , wherein a level of the first compensation voltage varies within a first voltage control range, based on the length of the vertical front porch period, and

wherein the first voltage control range is within a voltage range that is lower than a lower limit output value of the data voltage.

6 . The display apparatus of claim 5 , wherein a level of the first compensation voltage decreases stage-by-stage within the first voltage control range in real time in proportion to the length of the vertical front porch period.

7 . The display apparatus of claim 3 , wherein an electric potential of the reference voltage line in the vertical active period is the reference voltage,

wherein an electric potential of the reference voltage line in the vertical front porch period is changed from the reference voltage to a second compensation voltage that is greater than the reference voltage, and

wherein a gate-source voltage of a driving transistor included in each subpixel is lower in the vertical front porch period than in the vertical active period.

8 . The display apparatus of claim 7 , wherein a level of the second compensation voltage varies within a second voltage control range, based on the length of the vertical front porch period, and

wherein the second voltage control range is within a voltage range that is greater than the reference voltage.

9 . The display apparatus of claim 8 , wherein a level of the second compensation voltage increases stage-by-stage within the second voltage control range in real time in proportion to the length of the vertical front porch period.

10 . The display apparatus of claim 2 , wherein the flicker compensation circuit includes a counter configured to count a number of horizontal synchronization signals during the vertical front porch period to generate a count value.

11 . The display apparatus of claim 10 , wherein the flicker compensation circuit is further configured to determine a level of the compensation voltage based on the count value generated by the counter.

12 . The display apparatus of claim 11 , wherein the flicker compensation circuit is further configured to adjust the level of the compensation voltage such that a difference between the blank luminance and the active luminance increases as the count value increases.

13 . The display apparatus of claim 1 , wherein each of the plurality of subpixels includes a driving transistor configured to control a driving current,

wherein the data line is electrically connected to a gate electrode of the driving transistor, and

wherein the reference voltage line is electrically connected to a source electrode of the driving transistor.

14 . The display apparatus of claim 13 , wherein the compensation voltage is configured to control a gate-source voltage of the driving transistor during the vertical front porch period to be lower than a gate-source voltage of the driving transistor during the vertical active period.

15 . The display apparatus of claim 1 , wherein the vertical active period corresponds to a period in which a data enable signal supplied to the image driving circuit is active, and

wherein the vertical blank period corresponds to a period in which the data enable signal is inactive.

16 . The display apparatus of claim 1 , wherein the image driving circuit is configured to drive the display panel at a variable frame frequency, and

wherein the flicker compensation circuit is configured to increase a magnitude of the compensation voltage as the variable frame frequency decreases.