Method and system for controlling an active matrix display device
In the liquid crystal display device having a back-light source for illumination, image data is provided to the panel in successive frames such that the optical response of the liquid crystal in each pixel within a frame period has an impulse-like shape. The back-light source is controlled to illuminate the liquid crystal display panel such that the illumination is provided to the pixels for only part of the frame period. The optical response curve has a rising portion followed by a falling portion, and the back-light source is controlled by a timing control module such that the back-light is turned off at least when the optical response curve is in the falling portion. It is also possible to remove the image data from the pixels, or to control the charging and discharging of the electrodes to produce the impulse-like shape.
1. A method for operating a liquid-crystal display panel having a liquid crystal layer defining a plurality of pixels and a back-light source disposed in relationship to the liquid-crystal display panel, wherein the liquid crystal display panel has a front side for viewing and an opposing back side and wherein the back-light source is adapted to provide light to illuminate the liquid crystal display panel from the back side, said method comprising:
providing image data to at least some of the pixels for forming an image in successive frames, each frame having a frame period; and
controlling the back-light source so that said illuminating is provided to said pixels for only part of the frame period, wherein said controlling comprises turning on at least part of the back-light source in a first portion of the frame period and turning off said part of the back-light source in a second portion of the frame period, and wherein the first portion precedes the second portion.
2. The method of claim 1 , wherein the image data provided to said at least some of the pixels causes the light, transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and wherein at least part of the falling portion coincides with at least part of the second portion of the frame period.
3. The method of claim 2 , wherein the image data provided to said at least some of the pixels is removed from said pixels for producing the optical response.
4. The method of claim 1 , wherein a charging and discharging of electrodes associated with said at least some of the pixels causes the light transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and wherein at least part of the falling portion coincides with at least part of the second portion of the frame period.
5. The method of claim 1 , wherein said controlling further comprises turning off said at least part of the back-light source in another portion of frame period preceding the first portion.
6. The method of claim 1 , wherein the pixels are arranged in a plurality of lines and the image data is provided to the lines in a scanning pattern in a scanning direction, and wherein the back-light source comprises a plurality of light source sections and said controlling comprises turning off one section at a time in a sequential manner within the frame period also in a direction substantially parallel to the scanning direction and substantially in synchronism with the scanning pattern.
7. The method of claim 1 , wherein said controlling comprises turning on at least part of the back-light source in a first portion of the frame period in steps and turning off said part of the back-light source in a second portion of the frame period.
8. The method of claim 7 , wherein the steps include descending steps, and wherein the image data provided to said at least some of the pixels causes the light transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and at least part of the falling portion coincides with at least part of the descending steps.
9. The method of claim 8 , wherein the steps further include ascending steps preceding the descending steps.
10. A liquid-crystal display device comprising:
a liquid-crystal display panel having a liquid crystal layer defining a plurality of pixels, wherein image data is provided to at least some of the pixels for forming an image in successive frames, each frame having a frame period, and wherein the liquid crystal display panel has a front side for viewing and an opposing back side;
a back-light source disposed in relationship to the liquid-crystal display panel for providing light to illuminate the liquid crystal display panel from the back side; and
a back-light control module for controlling the back-light source so that the light is provided to illuminate said pixels for only part of the frame period, wherein the back-light control module is configured to turn on at least part of the back-light source in a first portion of the frame period and turn off said part of the back-light source in a second portion of the frame period, and wherein the first portion precedes the second portion.
11. The liquid crystal display device of claim 10 , further comprising
a data generator for providing the image data to said at least some of the pixels in a controlled fashion, causing light transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and wherein at least part of the falling portion coincides with at least part of the second portion of the frame period.
12. The liquid crystal display device of claim 11 , wherein the data generator is configured to remove part of the image data provided to said at least some of the pixels for producing the optical response.
13. The liquid crystal display device of claim 10 , further comprising
a charging time controller for controlling charging and discharging of electrodes associated with said at least some of the pixels, causing the light transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and wherein at least part of the falling portion coincides with at least part of the second portion of the frame period.
14. The liquid crystal display device of claim 10 , wherein the back-light control module is configured to turn off said at least part of the back-light source in another portion of the frame period preceding the first portion.
15. The liquid crystal display device of claim 10 , wherein the pixels are arranged in a plurality of lines and the image data is provided to the lines in a scanning pattern in a scanning direction, and wherein the back-light source comprises a plurality of light source sections and the back-light control module is configured to turn off one section at a time in a sequential manner within the frame period also in a direction substantially parallel to the scanning direction and substantially in synchronism with the scanning pattern.
16. The liquid crystal display device of claim 10 , wherein the back-light control module is configured to turn on at least part of the back-light source in a first portion of the frame period in steps and turn off said part of the back-light source in a second portion of the frame period.
17. A timing control device for use in a liquid-crystal display device comprising:
a liquid crystal display panel having a liquid crystal layer defining a plurality of pixels, wherein image data is provided to at least some of the pixels for forming an image in successive frames, each frame having a frame period, wherein the liquid crystal display panel has a front side for viewing and an opposing back side; and
a back-light source disposed in relationship to the liquid-crystal display panel for providing light to illuminate the liquid crystal display panel from the back side, said timing control device comprising:
an optical response control module for causing the light transmitted in said pixels to produce an optical response having a rising portion followed by a falling portion in the frame period, and wherein at least part of the falling portion coincides with at least part of the second portion of the frame period; and
a back-light control module for controlling the back-light source so that said illuminating is provided to said pixels for only part of the frame period, wherein the back-light control module is configured to turn on at least part of the back-light source in a first portion of the frame period and turn off said part of the back-light source in a second portion of the frame period, and wherein the first portion precedes the second portion.
18. The timing control device of claim 17 , wherein the back-light control module is configured to turn off said at least part of the back-light source in another portion of the frame period preceding the first portion.
19. The timing control device of claim 17 , wherein the pixels are arranged in a plurality of lines and the image data is provided to the lines in a scanning pattern in a scanning direction, and wherein the back-light source comprises a plurality of light source sections and the back-light control module is configured to turn off one section at a time in a sequential manner within the frame period also in a direction substantially parallel to the scanning direction and substantially in synchronism with the scanning pattern.