APPLICATION OF VOLTAGE TO DATA LINES DURING VCOM TOGGLING

• US 20120299970A1
• Filed: 05/24/2011
• Published: 11/29/2012
• Est. Priority Date: 05/24/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bae, Hopil, Yousefpor, Marduke
• Granted Patent: US 8,593,491 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0219 Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

With respect to liquid crystal display inversion schemes, a large change in voltage on a data line can affect the voltages on adjacent floating data lines due to capacitive coupling between data lines. The change in voltage on these floating data lines can be increased when the application of voltage to the data line occurs after a toggling operation of the Vcom, i.e., when a voltage applied to the Vcom changes the voltage on the Vcom from one polarity to an opposite polarity. Various embodiments of the present disclosure serve to eliminate or reduce the effects of Vcom voltage toggling on data line voltages by applying a voltage (e.g., a fixed voltage) to the data lines while the voltage on Vcom toggles.

Claims

1. A method of scanning a display, the display including a plurality of lines of sub-pixels, each sub-pixel being associated with one of a plurality of data lines, the method comprising:

applying a first voltage to a common electrode of the sub-pixels;

scanning a first line of sub-pixels while the first voltage is being applied to the common electrode, wherein scanning the first line includes connecting a first subset of the data lines to voltage sources while remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines;

applying, during a first time period after the scanning of the first line and before a scanning of a second line of sub-pixels, a second voltage to the common electrode, wherein the second voltage is different than the first voltage;

connecting, during the first time period, the plurality of data lines to the voltage sources, such that the data lines are connected to the voltage sources concurrently with the second voltage being applied to the common electrode; and

scanning the second line of sub-pixels while the second voltage is being applied to the common electrode, wherein scanning the second line includes connecting the first subset of the data lines to the voltage sources while the remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines.

2. The method of claim 1, wherein the polarity of the second voltage is different that the polarity of the first voltage.

3. The method of claim 1, wherein, during the first time period, the plurality of data lines are connected to the voltage sources before the second voltage is applied to the common electrode.

4. The method of claim 1, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes connecting two of the data lines to the same voltage source.

5. The method of claim 4, wherein each set of a plurality of sets of three adjacent data lines is associated with a display pixel in each line of sub-pixels, and wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes connecting the data lines in each set of data lines to the same voltage source.

6. The method of claim 5, wherein the connecting, during the first time period, the plurality of data lines to the voltage sources further includes connecting each of the sets of three data lines to a different voltage source than each of the other sets.

7. The method of claim 1, wherein the scanning of the first and second lines occurs during the scanning of a single frame of the display.

8. The method of claim 1, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including voltages with magnitudes less than voltages applied to the data lines during the scanning of the first line.

9. The method of claim 1, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including one of a ground voltage and a mid-level gray voltage.

10. An apparatus comprising:

a display screen including a plurality of lines of sub-pixels, each sub-pixel being associated with one of a plurality of data lines; and

a display driver, the display driver configured to

apply a first voltage to a common electrode of the sub-pixels,

scan a first line of sub-pixels while the first voltage is being applied to the common electrode, wherein scanning the first line includes connecting a first subset of the data lines to voltage sources while the remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines,

apply, during a first time period after the scanning of the first line and before a scanning of a second line of sub-pixels, a second voltage to the common electrode, wherein the second voltage is different than the first voltage,

connect, during the first time period, the plurality of data lines to the voltage sources, such that the data lines are connected to the voltage sources concurrently with the second voltage being applied to the common electrode, and

scan the second line of sub-pixels while the second voltage is being applied to the common electrode, wherein scanning the second line includes connecting the first subset of the data lines to the voltage sources while the remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines.

11. The apparatus of claim 10, wherein the polarity of the second voltage is different that the polarity of the first voltage.

12. The apparatus of claim 10, wherein, during the first time period, the plurality of data lines are connected to the voltage sources before the second voltage is applied to the common electrode.

13. The apparatus of claim 10, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes connecting two of the data lines to the same voltage source.

14. The apparatus of claim 13, further comprising:

a plurality of demultiplexers, each demultiplexer associated with one of a plurality of sets of three adjacent data lines, each set being associated with a display pixel in each line of sub-pixels, and wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes closing switches in each demultiplexer to connect the data lines in each set of data lines to the same voltage source.

15. The apparatus of claim 14, wherein each demultiplexer is connected to a different voltage source, such that connecting, during the first time period, the plurality of data lines to the voltage sources further includes connecting each of the sets of three data lines to a different voltage source than each of the other sets.

16. The apparatus of claim 10, wherein the scanning of the first and second lines occurs during the scanning of a single frame of the display.

17. The apparatus of claim 10, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including voltages with magnitudes less than voltages applied to the data lines during the scanning of the first line.

18. The apparatus of claim 10, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including one of a ground voltage and a mid-level gray voltage.

19. A non-transitory computer-readable storage medium storing computer-readable program instructions executable to perform a method of scanning a display, the display including a plurality of lines of sub-pixels, each sub-pixel being associated with one of a plurality of data lines, the method comprising:

applying a first voltage to a common electrode of the sub-pixels;

scanning a first line of sub-pixels while the first voltage is being applied to the common electrode, wherein scanning the first line includes connecting a first subset of the data lines to voltage sources while the remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines;

applying, during a first time period after the scanning of the first line and before a scanning of a second line of sub-pixels, a second voltage to the common electrode, wherein the second voltage is different than the first voltage;

connecting, during the first time period, the plurality of data lines to the voltage sources, such that the data lines are connected to the voltage sources concurrently with the second voltage being applied to the common electrode;

scanning the second line of sub-pixels while the second voltage is being applied to the common electrode, wherein scanning the second line includes connecting the first subset of the data lines to the voltage sources while the remaining data lines are disconnected from the voltage sources, applying data voltages to the first subset of data lines, disconnecting the first subset of data lines from the voltage sources, connecting a second subset of the data lines to the voltage sources, and applying data voltages to the second subset of data lines.

20. The non-transitory computer-readable storage medium of claim 19, wherein the polarity of the second voltage is different that the polarity of the first voltage.

21. The non-transitory computer-readable storage medium of claim 19, wherein, during the first time period, the plurality of data lines are connected to the voltage sources before the second voltage is applied to the common electrode.

22. The non-transitory computer-readable storage medium of claim 19, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes connecting two of the data lines to the same voltage source.

23. The non-transitory computer-readable storage medium of claim 19, wherein the scanning of the first and second lines occurs during the scanning of a single frame of the display.

24. The non-transitory computer-readable storage medium of claim 19, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including voltages with magnitudes less than voltages applied to the data lines during the scanning of the first line.

25. The non-transitory computer-readable storage medium of claim 19, wherein connecting, during the first time period, the plurality of data lines to the voltage sources includes applying one or more fixed voltages to the data lines, the one or more fixed voltages including one of a ground voltage and a mid-level gray voltage.