Display panel driver, method of driving display panel using the same and display apparatus having the same
A display panel driver that includes a compensating value generating part, a compensating lookup table and a compensating part. The compensating value generating part generates an offset and a compensating grayscale based on luminances of pixels of a display panel. The compensating lookup table stores the offset and the compensating grayscale. The compensating part compensates an input grayscale of the pixel to generate a data signal using the compensating lookup table.
1. A display panel driver, comprising:
a compensating value generating part generating an offset and a compensating grayscale based on luminances of pixels of a display panel;
a compensating lookup table storing the offset and the compensating grayscale; and
a compensating part compensating an input grayscale of the pixel to generate a data signal using the compensating lookup table,
wherein the offset is set based on a maximum luminance of the pixels and a minimum luminance of the pixels when the same grayscale is applied to the pixels.
2. The display panel driver of claim 1 , wherein when the maximum luminance is LMAX, the minimum luminance is LMIN and the number of bits of the compensating lookup table is X,
OFFSET
=
L
MIN
L
MAX
×
(
2
X
-
1
)
1
-
L
MIN
L
MAX
.
3. The display panel driver of claim 1 , wherein the compensating grayscale of a first pixel is set based on the offset, a minimum luminance of the pixels and a luminance of the first pixel.
4. The display panel driver of claim 3 , wherein when the offset is OFFSET, the luminance of the first pixel is L 1 , the minimum luminance is LMIN and the number of bits of the compensating lookup table is X, the compensating grayscale (COMP 1 ) of the first pixel is
COMP
1
=
(
2
X
-
1
+
OFFSET
)
×
L
MIN
L
1
-
OFFSET
.
5. The display panel driver of claim 1 , wherein when the input grayscale is IGS, the offset is OFFSET, the compensating grayscale is COMP and the number of bits of the compensating lookup table is X, a grayscale (OGS) of the data signal is
OGS
=
IGS
×
COMP
+
OFFSET
2
X
-
1
+
OFFSET
.
6. The display panel driver of claim 1 , wherein the compensating value generating part generates a first offset and a first compensating value based on first pixels having a first color, a second offset and a second compensating value based on second pixels having a second color, a third offset and a third compensating value based on third pixels having a third color.
7. A display apparatus, comprising:
a display panel comprising a plurality of gate lines, a plurality of data lines and a plurality of pixels connected to the gate lines and the data lines; and
a display panel driver comprising
a compensating value generating part generating an offset and a compensating grayscale based on luminances of the pixels,
a compensating lookup table storing the offset and the compensating grayscale and
a compensating part compensating an input grayscale of the pixel to generate a data signal using the compensating lookup table,
wherein the offset is set based on a maximum luminance of the pixels and a minimum luminance of the pixels when the same grayscale is applied to the pixels.
8. The display apparatus of claim 7 , wherein the pixel comprises:
a switching transistor including a control electrode connected to the gate line, an input electrode connected to the data line and an output electrode connected to a first node;
a driving transistor including a control electrode connected to the first node, an input electrode connected to a second node and an output electrode connected to a first electrode of an organic light emitting element;
a bias transistor including a control electrode to which a bias voltage is applied, an input electrode to which a high power voltage is applied and an output electrode connected to the second node;
a first capacitor including a first end to which the high power voltage is applied and a second end connected to the first node;
a second capacitor including a first end to which the high power voltage is applied and a second end connected to the control electrode of the bias transistor; and
the light organic light emitting element including the first electrode connected to the output electrode of the driving transistor and a second electrode to which a low power voltage is applied.
9. The display apparatus of claim 7 , wherein when the maximum luminance is LMAX, the minimum luminance is LMIN and the number of bits of the compensating lookup table is X,
OFFSET
=
L
MIN
L
MAX
×
(
2
X
-
1
)
1
-
L
MIN
L
MAX
.
10. The display apparatus of claim 7 , wherein the compensating grayscale of a first pixel is set based on the offset, a minimum luminance of the pixels and a luminance of the first pixel.
11. The display apparatus of claim 10 , wherein when the offset is OFFSET, the luminance of the first pixel is L 1 , the minimum luminance is LMIN and the number of bits of the compensating lookup table is X, the compensating grayscale (COMP 1 ) of the first pixel is
COMP
1
=
(
2
X
-
1
+
OFFSET
)
×
L
MIN
L
1
-
OFFSET
.
12. The display apparatus of claim 7 , wherein when the input grayscale is IGS, the offset is OFFSET, the compensating grayscale is COMP and the number of bits of the compensating lookup table is X, a grayscale (OGS) of the data signal is
OGS
=
IGS
×
COMP
+
OFFSET
2
X
-
1
+
OFFSET
.
13. The display apparatus of claim 7 , wherein the compensating value generating part generates a first offset and a first compensating value based on first pixels having a first color, a second offset and a second compensating value based on second pixels having a second color, a third offset and a third compensating value based on third pixels having a third color.
14. A method of driving a display panel, the method comprising:
generating an offset and a compensating grayscale based on luminances of pixels of a display panel;
storing the offset and the compensating grayscale in a compensating lookup table; and
compensating an input grayscale of the pixel to generate a data signal using the compensating lookup table,
wherein the offset is set based on a maximum luminance of the pixels and a minimum luminance of the pixels when the same grayscale is applied to the pixels.
15. The method of claim 14 , wherein the compensating grayscale of a first pixel is set based on the offset, a minimum luminance of the pixels and a luminance of the first pixel.
16. The method of claim 14 , wherein when the input grayscale is IGS, the offset is OFFSET, the compensating grayscale is COMP and the number of bits of the compensating lookup table is X, a grayscale (OGS) of the data signal is
OGS
=
IGS
×
COMP
+
OFFSET
2
X
-
1
+
OFFSET
.
17. The method of claim 14 , wherein the storing the offset and the compensating grayscale comprises:
generating a first offset and a first compensating value based on first pixels having a first color;
generating a second offset and a second compensating value based on second pixels having a second color; and
generating a third offset and a third compensating value based on third pixels having a third color.