Device and method for display brightness control
A display driver includes gamma curve control circuitry and a converter controller. The gamma curve control circuitry is configured to generate a first gamma curve for a first display brightness value (DBV), and a second gamma curve for a second DBV lower than the first DBV. The converter controller is configured to control a digital-analog converter (DAC) configured to perform digital-analog conversion of an input image data. Further, the converter controller is configured to adjust an analog signal voltage amplitude of the DAC based on a range of an output voltage associated with the second gamma curve.
1. A method of displaying an image, comprising:
receiving a display brightness value (“DBV”) for displaying the image;
selecting, based at least in part on the DBV, a display mode for the image from a set of pre-defined display modes,
wherein each display mode has a corresponding brightness level, and all display modes have N grayscale levels, where N is an integer, and
wherein each of the display modes in the set of predefined display modes is used to
display image data on a same set of pixels of a display panel; and
displaying the image on the display panel according to a pre-defined gamma value and at least one control parameter corresponding to the display mode.
2. The method of claim 1 , wherein selecting the corresponding display mode includes selecting a brightness control sub-table entry from a brightness control table.
3. The method of claim 2 , wherein the brightness control sub-table entries respectively corresponding to the value of the at least one control parameter.
4. The method of claim 1 , wherein the at least one control parameter is a set of control parameters including at least two of the following:
a curve control parameter, a brightness control parameter, a digital to analog controller (DAC) top voltage control parameter, a DAC bottom voltage control parameter, and an emission pulse control parameter.
5. The method of claim 1 , wherein displaying the image on the display panel further includes generating a gamma curve, using the pre-defined gamma value, corresponding to the selected display mode.
6. The method of claim 1 , wherein the set of pre-defined display modes varies as to a range of voltage between a top output voltage level and a bottom output voltage level of a DAC coupled to the display panel.
7. The method of claim 6 , wherein the N grayscale levels are analog input voltage levels of the DAC.
8. The method of claim 1 , wherein the set of display modes comprises normal display modes and high brightness display modes.
9. The method of claim 8 , wherein at least one of:
the normal display modes have an emission pulse duty ratio between 25% and 50%, and wherein the high brightness display modes have an emission pulse duty ratio between 50% and 99%; or
the normal display modes each have a first analog signal voltage amplitude (“ASVA”) and the high brightness display modes each have a second ASVA, the second ASVA larger than the first ASVA.
10. The method of claim 8 , wherein the normal display modes each have a first DAC bottom voltage and the high brightness display modes each have a second DAC bottom voltage, the second DAC bottom voltage lower than the first DAC bottom voltage.
11. The method of claim 1 , wherein the pre-defined gamma value is 2.2, and wherein N=256.
12. The method of claim 1 , wherein the set of pre-defined display modes varies as to emission pulse duty ratio.
13. A display driver, comprising:
control circuitry configured to:
receive a display brightness value (“DBV”) and control signals for displaying an image;
select, based at least in part on the DBV, a display mode for the image from a set of pre-defined display modes,
wherein each display mode has a corresponding brightness level, and all display modes have N grayscale levels, where N is an integer, and
wherein each of the display modes in the set of predefined display modes is used to display image data on a same set of pixels of a display panel; and
display the image on the display panel according to a pre-defined gamma value and at least one control parameter corresponding to the display mode.
14. The display driver of claim 13 , further comprising a memory coupled to the control circuitry, wherein a brightness control table is stored in the memory.
15. The display driver of claim 14 , wherein selecting the display mode from the set of pre-defined display modes includes selecting a brightness control sub-table entry from the brightness control table.
16. The display driver of claim 13 , wherein the at least one control parameter is a set of control parameters including at least two of the following:
a curve control parameter, a brightness control parameter, a digital to analog controller (DAC) top voltage control parameter, a DAC bottom voltage control parameter, and an emission pulse control parameter.
17. The display driver of claim 13 , wherein the set of display modes is divided into normal display modes and high brightness display modes, and wherein at least one of:
the normal display modes have an emission pulse duty ratio between 25% and 50%, and wherein the high brightness display modes have an emission pulse duty ratio between 50% and 99%; or
the normal display modes each have a first analog signal voltage amplitude (“ASVA”) and the high brightness display modes each have a second ASVA, the second ASVA larger than the first ASVA.
18. A display device, comprising:
a display panel; and
a display driver configured to drive the display panel, wherein the display driver comprises:
control circuitry configured to:
receive a display brightness value (“DBV”) and control signals for displaying an image;
select, based at least in part on the DBV, a display mode for the image from a set of pre-defined display modes,
wherein each display mode has a corresponding brightness level, and all display modes have N grayscale levels, where N is an integer, and
wherein each of the display modes in the set of predefined display modes is used to display image data on a same set of pixels of the display panel; and
display the image on the display panel according to a pre-defined gamma value and at least one control parameter corresponding to the display mode.
19. The display device of claim 18 , further comprising a DAC coupled to the control circuitry and to the display panel, wherein the set of pre-defined display modes varies as to at least one of:
a range of voltage between a top output voltage level and a bottom output voltage level of the DAC; or
emission pulse duty ratio.
20. The display device of claim 18 , wherein the set of display modes is divided into normal display modes and high brightness display modes.
21. The display device of claim 20 ,
wherein the normal display modes each have a first DAC bottom output voltage and the high brightness display modes each have a second DAC bottom output voltage, the second DAC bottom output voltage lower than the first DAC bottom output voltage.