Dynamic overdrive for liquid crystal displays

• US 10,770,023 B2
• Filed: 08/29/2018
• Issued: 09/08/2020
• Est. Priority Date: 05/29/2018
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Morein, Stephen L.
• Primary Examiner(s): Earles, Bryan
• Application Number:
  US16/116,862
• Publication Number:
  US 20190371258A1
• Time in Patent Office: 741 Days
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A method and apparatus for overdriving pixel elements to a desired voltage. A display device comprises a pixel array and overdrive circuitry to determine a current pixel value for a first pixel element of the pixel array and a target pixel value for the first pixel element. The overdrive circuitry is further configured to determine a first voltage to be applied to the first pixel element to cause the first pixel element to transition from the current pixel value to the target pixel value by a first instance of time. The first voltage is determined based at least in part on a position of the first pixel element in the pixel array. The display device further comprises a data driver to apply the first voltage to the first pixel element before the first instance of time and a backlight to illuminate the pixel array at the first instance of time.

Claims

1. A method, comprising:

determining a current pixel value for a first pixel element of a pixel array;

determining a target pixel value for the first pixel element;

determining a target voltage which causes the first pixel element to settle at the target pixel value;

selecting the target voltage or an overdrive voltage to be applied to the first pixel element to cause the first pixel element to transition from the current pixel value to the target pixel value by a first instance of time, wherein the selection is based at least in part on a position of the first pixel element in the pixel array;

applying the selected voltage to the first pixel element before the first instance of time; and

activating one or more light sources to illuminate the pixel array at the first instance of time.

2. The method of claim 1, wherein the position corresponds to a row position of the first pixel element in the pixel array.

3. The method of claim 2, wherein the target voltage is selected when the row position of the first pixel element is located below a threshold line number of the pixel array.

4. The method of claim 3, wherein the overdrive voltage is selected when the row position of the first pixel element is located above the threshold line number of the pixel array, wherein the overdrive voltage is different than the target voltage.

5. The method of claim 1, further comprising:

determining the overdrive voltage based at least in part on a plurality of lookup tables (LUTs), wherein each of the LUTs indicates a plurality of overdrive voltages for pixel elements in a corresponding row of the pixel array.

6. The method of claim 5, wherein the determining of the overdrive voltage further comprises:

selecting a first LUT of the plurality of LUTs based at least in part on the row position of the first pixel element, wherein the first LUT is associated with a row of the pixel array below the row position of the first pixel element;

selecting a second LUT of the plurality LUTs based at least in part on the row position of the first pixel element, wherein the second LUT is associated with a row of the pixel array above the row position of the first pixel element; and

determining the overdrive voltage based at least in part on a linear interpolation of the first LUT and the second LUT.

7. The method of claim 6, wherein the determining of the overdrive voltage further comprises:

generating an interpolated LUT based on the linear interpolation of the first and second LUTs;

selecting at least two rows of the interpolated LUT based on the current pixel value;

selecting at least two columns of the interpolated LUT based on the target pixel value; and

determining the overdrive voltage based on a bilinear interpolation of the selected rows and columns of the interpolated LUT.

8. The method of claim 6, wherein the first and second LUTs are selected based at least in part on a temperature of the pixel array.

9. The method of claim 1, further comprising:

determining a first voltage to be applied to a second pixel element of the pixel array to cause the second pixel element to transition from the current pixel value to the target pixel value by the first instance of time, wherein the first voltage is different than the selected voltage for the first pixel element.

10. The method of claim 9, further comprising:

applying the first voltage to the second pixel element before the first instance of time, wherein the first pixel element is located in a different row of the pixel array than the first pixel element.

11. A display device comprising:

a pixel array;

overdrive circuitry configured to;

determine a current pixel value for a first pixel element of the pixel array;

determine a target pixel value for the first pixel element;

determine a target voltage which causes the first pixel element to settle at the target pixel value; and

select the target voltage or an overdrive voltage to be applied to the first pixel element to cause the first pixel element to transition from the current pixel value to the target pixel value by a first instance of time, wherein the selection is based at least in part on a position of the first pixel element in the pixel array;

a data driver configured to apply the selected voltage to the first pixel element before the first instance of time; and

a backlight configured to illuminate the pixel array at the first instance of time.

12. The display device of claim 11, wherein the position corresponds to a row position of the first pixel element in the pixel array.

13. The display device of claim 12, wherein the target voltage is selected when the row position of the first pixel element is located below a threshold line number of the pixel array.

14. The display device of claim 13, wherein the overdrive voltage is selected when the row position is located above the threshold line number of the pixel array, wherein the overdrive voltage is different than the target voltage.

15. The display device of claim 11, wherein the overdrive circuitry comprises:

a lookup table (LUT) repository configured to store a plurality of LUTs, wherein each of the LUTs indicates a plurality of overdrive voltages for pixel elements in a corresponding row of the pixel array; and

an overdrive voltage generator to determine the overdrive voltage based at least in part on the plurality of LUTs.

16. The display device of claim 15, wherein the overdrive voltage generator is further configured to:

select a first LUT of the plurality of LUTs based at least in part on the row position of the first pixel element, wherein the first LUT is associated with a row of the pixel array below the row position of the first pixel element;

select a second LUT of the plurality LUTs based at least in part on the row position of the first pixel element, wherein the second LUT is associated with a row of the pixel array above the row position of the first pixel element; and

determine the overdrive voltage based at least in part on a linear interpolation of the first LUT and the second LUT.

17. The display device of claim 16, wherein the overdrive voltage generator comprises:

an LUT generator configured to generate an interpolated LUT based on the linear interpolation of the first and second LUTs; and

an overdrive voltage interpolator configured to;

select at least two rows of the interpolated LUT based on the current pixel value;

select at least two columns of the interpolated LUT based on the target pixel value; and

determine the overdrive voltage based on a bilinear interpolation of the selected rows and columns of the interpolated LUT.

18. The display device of claim 16, wherein the overdrive voltage generator is to select the first and second LUTs based at least in part on a temperature of the display device.

19. The display device of claim 11, wherein the overdrive circuitry is further configured to:

determine a first voltage to be applied to a second pixel element of the pixel array to cause the second pixel element to transition from the current pixel value to the target pixel value by the first instance of time, wherein the first voltage is different than the selected voltage for the first pixel element.

20. The display device of claim 19, wherein the data driver is further configured to:

apply the first voltage to the second pixel element before the first instance of time, wherein the first pixel element is located in a different row of the pixel array than the first pixel element.