Display apparatus and display apparatus control method
A display apparatus includes a liquid crystal display (LCD) panel and a backlight coupled to the LCD panel. The LCD apparatus is capable of being operated in a plurality of modes. The gradation values of the image data is adjusted in accordance with gradation ranges, each gradation range having an upper limit gradation value and a lower limit gradation value. The first converted image data is then scaled by applying a scaling factor, followed by adjustment of backlight brightness. The frame rate of the LCD apparatus is also adjusted to implement the operation mode.
1. A method of controlling a display apparatus, the method comprising:
determining a screen mode in which at least one among maximum brightness value, color temperature value and contrast ratio value is adjusted in accordance with surface reflectance, color temperature and contrast ratio of a physical paper;
determining gradation ranges for operating the display apparatus in the screen mode, each gradation range having an upper limit gradation value and a lower limit gradation value;
adjusting gradation values of an image data associated with each sub-pixel in a frame to generate a first converted image data for the frame, wherein the gradation values of the image data are adjusted to be within a range between the upper limit gradation value and the lower limit gradation value of the corresponding gradation range;
adjusting gradation values of the first converted image data associated with each sub-pixel in the frame by a scaling factor;
adjusting the brightness of a backlight by an inverse proportion of the scaling factor; and
adjusting a frame rate of the display apparatus.
2. The method of claim 1 , wherein the first converted image data includes the gradation values associated with a plurality of red sub-pixels, a plurality of green sub-pixels, and a plurality of blue sub-pixels that are adjusted by the following equation,
R
output
=
R
min
+
R
max
-
R
min
2
n
-
1
×
R
input
Eqn
(
1
)
G
output
=
G
min
+
G
max
-
G
min
2
n
-
1
×
G
input
Eqn
(
2
)
B
output
=
B
min
+
B
max
-
B
min
2
n
-
1
×
B
input
Eqn
(
3
)
wherein, R input , G input and B input denote initial gradation values of the image data associated with one of the red sub-pixel, one of the green sub-pixel and one of the blue sub-pixel; R output , G output and B output denote the gradation values in the first converted image data; R max , G max and B max denote the upper limits of the respective gradation range; R min , G min and B min denote the lower limits of the respective gradation range; and n denotes the number of bits of the image data.
3. The method of claim 1 , wherein the scaling factor is calculated by the following equation,
Scaling
factor
=
(
maximum
gradation
value
highest
gradation
value
of
the
first
converted
image
data
)
Eqn
4
wherein the maximum gradation value is associated with one among red, green and blue sub-pixels.
4. The method of claim 1 , wherein the generation of the first converted image data and the calculation of the scaling factor is performed for a plurality of frames.
5. The method of claim 1 , wherein the frame rate is adjusted in accordance to a comparison result between the image data of a plurality of frames.
6. The method of claim 5 , wherein the frame rate of the display apparatus is reduced by reducing a frequency of a source output enable (SOE) signal.
7. The method of claim 1 , further comprising adjusting a polarity (POL) inversion period of the display apparatus.
8. The method of claim 7 , wherein the POL inversion period is at least two times longer than a period of one frame.
9. The method of claim 8 , wherein the POL inversion period is between 100 ms to 500 ms.
10. The method of claim 1 , wherein the frame rate of the display apparatus is adjusted in a step-wise manner.
11. A display apparatus comprising:
a liquid crystal display (LCD) panel;
a backlight coupled to the LCD panel; and
a controller configured to
determine a screen mode in which at least one among maximum brightness value, color temperature value and contrast ratio value is adjusted in accordance with surface reflectance, color temperature and contrast ratio of a physical paper;
determine gradation ranges for operating the display apparatus in the screen mode, each gradation range having an upper limit gradation value and a lower limit gradation value;
adjust gradation values of an image data associated with each sub-pixel in a frame to generate a first converted image data for the frame, wherein the gradation values of the image data are adjusted to be within a range between the upper limit gradation value and the lower limit gradation value of the corresponding gradation range;
adjust gradation values of the first converted image data associated with each sub-pixel in the frame by a scaling factor;
adjust the brightness of a backlight by an inverse proportion of the scaling factor, and
adjust a frame rate of the display apparatus.
12. The display apparatus of claim 11 , wherein the generation of the first converted image data and the calculation of the scaling factor is performed for a plurality of frames.
13. The display apparatus of claim 11 , wherein the frame rate of the display apparatus is reduced by reducing a frequency of a source output enable (SOE) signal.
14. The display apparatus of claim 11 , wherein the LCD panel includes a thin-film transistor having a semiconductor layer of which off-state current is 1×10 −15 A or less.
15. The display apparatus of claim 11 , further comprising adjusting a polarity (POL) inversion period of the display apparatus.
16. The display apparatus of claim 15 , wherein the POL inversion period is at least two times longer than a period of one frame.
17. The display apparatus of claim 11 , wherein the frame rate of the display apparatus is adjusted in a step-wise manner.
18. A controller for a display apparatus, wherein the controller is operable to
determine a screen mode of operation for a display apparatus in which at least one among maximum brightness value, color temperature value and contrast ratio value is adjusted in accordance with surface reflectance, color temperature and contrast ratio of a physical paper;
determine gradation ranges for operating the display apparatus in the screen mode, each gradation range having an upper limit gradation value and a lower limit gradation value;
adjust gradation values of an image data associated with each sub-pixel in a frame to generate a first converted image data for the frame, wherein the gradation values of the image data are adjusted to be within a range between the upper limit gradation value and the lower limit gradation value of the corresponding gradation range;
adjust gradation values of the first converted image data associated with each sub-pixel in the frame by a scaling factor;
adjust the brightness of a backlight by an inverse proportion of the scaling factor, and
adjust a frame rate of the display apparatus.
19. The controller of claim 18 , wherein the first converted image data includes the gradation values associated with a plurality of red sub-pixels, a plurality of green sub-pixels, and a plurality of blue sub-pixels that are adjusted by the following equation,
R
output
=
R
min
+
R
max
-
R
min
2
n
-
1
×
R
input
Eqn
(
1
)
G
output
=
G
min
+
G
max
-
G
min
2
n
-
1
×
G
input
Eqn
(
2
)
B
output
=
B
min
+
B
max
-
B
min
2
n
-
1
×
B
input
Eqn
(
3
)
wherein, R input , G input and B input denote initial gradation values of the image data associated with one of the red sub-pixel, one of the green sub-pixel and one of the blue sub-pixel; R output , G output and B output denote the gradation values in the first converted image data; R max , G max and B max denote the upper limits of the respective gradation range; R min , G min and B min denote the lower limits of the respective gradation range; and n denotes the number of bits of the image data.
20. The controller of claim 18 , wherein the generation of the first converted image data and the calculation of the scaling factor is performed for a plurality of frames.