Backlight modulation for liquid crystal display with eyetracking for virtual reality

1. A head mounted display system comprising:

a display device including:

a liquid crystal (LC) panel comprising a plurality of rows of pixels;

a back light unit (BLU) configured to emit light toward the LC panel;

a data driver configured to write data corresponding to an image to the LC panel; and

a controller configured to apply a first control signal to the data driver to write the data to the LC panel and a second control signal to the BLU to emit light during an illumination period of a frame period from an illumination start time and to not emit light for a remaining portion of the frame period; and

an eyetracking device configured to determine an eye gaze area of a user in a pixel area of the display device, wherein the illumination start time varies based on a location of the eye gaze area such that the illumination start time is offset from a beginning of the frame period by a first amount and another illumination start time is offset from a beginning of another frame period by a second amount that varies, from the first amount, based on the location of the eye gaze area.

2. The head mounted display system of claim 1 , wherein liquid crystal material in a row of the pixels of the LC panel outside the eye gaze area of the user transitions during the illumination period.

3. The head mounted display system of claim 1 , wherein when the eye gaze area of the user is in a top portion of the pixel area, the illumination start time occurs before an end of the frame period.

4. The head mounted display system of claim 1 , wherein when the eye gaze area of the user is in a bottom portion of the pixel area of the display device, the illumination start time is at an end of the frame period or a beginning of a subsequent frame period.

5. The head mounted display system of claim 1 , wherein the data driver writes the data to a row of the pixels of the LC panel outside the eye gaze area in a subsequent frame period during at least a portion of the illumination period.

6. The head mounted display system of claim 1 , wherein when the eye gaze area of the user is in a middle portion of the pixel area of the display device, the illumination start time occurs before an end of the frame period and the illumination period extends into a subsequent frame period subsequent to said frame period.

7. The head mounted display system of claim 6 , wherein responsive to the eye gaze area of the user moving below a previous eye gaze area of the user, the illumination start time shifts closer to an end of the frame period.

8. The head mounted display system of claim 6 , wherein responsive to the eye gaze area of the user moving above a previous eye gaze area of the user, the illumination start time shifts closer to a start of the frame period.

9. The head mounted display system of claim 1 , wherein the data driver writes the data to the plurality of the rows of the pixels at a beginning portion of the frame period.

10. The head mounted display system of claim 9 , wherein the illumination start time occurs at or after an end of the beginning portion of the frame period.

11. A method of displaying an image by a display device, the method comprising:

writing, by a data driver, data corresponding to the image to a liquid crystal (LC) panel comprising a plurality of rows of pixels;

determining, by an eyetracking device, an eye gaze area of a user in a pixel area of the display device;

emitting, by a back light unit, light toward the LC panel during an illumination period of a frame from an illumination start time and not emitting light for a remaining portion of the frame period, wherein the illumination start time varies based on a location of the eye gaze area such that the illumination start time is offset from a beginning of the frame period by a first amount and another illumination start time is offset from a beginning of another frame period by a second amount that varies, from the first amount, based on the location of the eye gaze area.

12. The method of claim 11 , wherein liquid crystal material in a row of the pixels of the LC panel outside the eye gaze area of the user transitions during the illumination period.

13. The method of claim 11 , wherein when the eye gaze area of the user is in a top portion of the pixel area, the illumination start time occurs before an end of the frame period.

14. The method of claim 11 , wherein when the eye gaze area of the user is in a bottom portion of the pixel area of the display device, the illumination start time is at an end of the frame period or a beginning of a subsequent frame period.

15. The method of claim 11 , further comprising:

writing, by the data driver, the data to a row of the pixels of the LC panel outside the eye gaze area in a subsequent frame period during at least a portion of the illumination period.

16. The method of claim 11 , wherein when the eye gaze area of the user is in a middle portion of the pixel area of the display device, the illumination start time occurs before an end of the frame period such that the illumination period extends into a subsequent frame period subsequent to said frame period.

17. The method of claim 16 , wherein responsive to the eye gaze area of the user moving below a previous eye gaze area of the user, the illumination start time shifts closer to an end of the frame period.

18. The method of claim 16 , wherein responsive to the eye gaze area of the user moving above a previous eye gaze area of the user, the illumination start time shifts closer to a start of the frame period.

19. The method of claim 11 , wherein the data driver writes the data to the plurality of the rows of the pixels at a beginning portion of the frame period.

20. The method of claim 19 , wherein the illumination start time occurs at or after an end of the beginning portion of the frame period.