Pre-charging of sub-pixels

• US 8,717,345 B2
• Filed: 05/24/2011
• Issued: 05/06/2014
• Est. Priority Date: 05/24/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bae, Hopil, Yousefpor, Marduke, Ge, Zhibing
• Primary Examiner(s): Feild, Joseph
• Assistant Examiner(s): POLO, GUSTAVO D
• Application Number:
  US13/143,188
• Publication Number:
  US 20120299894A1
• Time in Patent Office: 1,078 Days
• Field of Search: 345 87-104, 345204-215
• US Class Current: 345/210
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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 3/3677 suitable for active matrices only

Abstract

Pre-charging display screen sub-pixels, such as aggressor sub-pixels, prior to the application of a target data voltage to the aggressor sub-pixels is provided. In some examples, a target voltage of a sub-pixel in a previous row in the scanning order of the display can be used to pre-charge sub-pixels. The row of sub-pixels to be pre-charged can be switched on during the updating of another row of sub-pixels. In this way, for example, target voltages applied to data lines while an update row is connected to the data lines, e.g., to update the update row, can be applied to the row to be pre-charged as well.

Claims

1. A method of updating an image displayed by a display screen in a first image frame, the display screen including a plurality of sub-pixels including a first sub-pixel with a first pixel electrode and a second sub-pixel with a second pixel electrode, the second sub-pixel being disposed adjacent to the first sub-pixel, the method comprising:

applying a first voltage to the second pixel electrode;

updating the first pixel electrode to a first target voltage value corresponding to a first luminance of the first sub-pixel by applying a second voltage to the first pixel electrode, the second voltage being applied after the application of the first voltage;

updating the second pixel electrode to a second target voltage value corresponding to a second luminance of the second sub-pixel by applying a third voltage to the second pixel electrode, the third voltage being applied after the application of the second voltage; and

applying the first voltage to a third pixel electrode of a third sub-pixel concurrently with the application of the first voltage to the second pixel electrode.

2. The method of claim 1, wherein the application of the first voltage changes a voltage polarity of the second pixel electrode.

3. The method of claim 1, wherein the first voltage includes one of ground, a mid-level gray voltage corresponding to a mid-level gray luminance of the sub-pixel, and a target voltage of a third pixel electrode of a third sub-pixel.

4. The method of claim 1, wherein applying the first voltage concurrently to the second and third pixel electrodes includes connecting the second and third pixel electrodes to a data line and applying the first voltage to the data line.

5. The method of claim 4, wherein the display screen includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes transmitting a first start frame pulse through the gate driver chain at a first time, and transmitting a second start frame pulse through the gate driver chain at a second time, such that the second gate driver receives the first start frame pulse and the third gate driver receives the second start frame pulse concurrently.

6. The method of claim 4, wherein the display screen includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes the third gate driver switching on the third transistor in response to receiving a first start frame pulse through the gate driver chain, and the second gate driver switching on the second transistor in response to receiving a second start frame pulse through a transmission path that is in parallel to the gate driver chain.

7. The method of claim 1, wherein the sub-pixels of the display screen are arranged in a plurality of update lines, each update line including a plurality of sub-pixels, wherein the first and second sub-pixels are disposed in a first update line and a second update line, respectively, the plurality of update lines being updated in predetermined scanning order, such that the update of the first update line occurs before the update of the second update line in the scanning order.

8. The method of claim 7, further comprising:

applying the first voltage to a third pixel electrode of a third sub-pixel, the second and third sub-pixels being updated in different blocks of update lines in the scanning order, such that the first voltage is applied concurrently to the second and third pixel electrodes.

9. An apparatus comprising:

a display screen including a plurality of sub-pixels including a first sub-pixel with a first pixel electrode and a second sub-pixel with a second pixel electrode, the second sub-pixel being disposed adjacent to the first sub-pixel; and

a pre-charging system that

applies a first voltage to the second pixel electrode,

updates the first pixel electrode to a first target voltage value corresponding to a first luminance of the first sub-pixel by applying a second voltage to the first pixel electrode, the second voltage being applied after the application of the first voltage,

updates the second pixel electrode to a second target voltage value corresponding to a second luminance of the second sub-pixel by applying a third voltage to the second pixel electrode, the third voltage being applied after the application of the second voltage; and

applies the first voltage to a third pixel electrode of a third sub-pixel concurrently with the application of the first voltage to the second pixel electrode.

10. The apparatus of claim 9, wherein the application of the first voltage changes a voltage polarity of the second pixel electrode.

11. The apparatus of claim 9, wherein the first voltage includes one of ground, a mid-level gray voltage corresponding to a mid-level gray luminance of the sub-pixel, and a target voltage of a third pixel electrode of a third sub-pixel.

12. The apparatus of claim 9, wherein applying the first voltage concurrently to the second and third pixel electrodes includes connecting the second and third pixel electrodes to a data line and applying the first voltage to the data line.

13. The apparatus of claim 12, wherein the pre-charging system includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes transmitting a first start frame pulse through the gate driver chain at a first time, and transmitting a second start frame pulse through the gate driver chain at a second time, such that the second gate driver receives the first start frame pulse and the third gate driver receives the second start frame pulse concurrently.

14. The apparatus of claim 12, wherein the pre-charging system includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes the third gate driver switching on the third transistor in response to receiving a first start frame pulse through the gate driver chain, and the second gate driver switching on the second transistor in response to receiving a second start frame pulse through a transmission path that is in parallel to the gate driver chain.

15. The apparatus of claim 9, wherein the sub-pixels of the display screen are arranged in a plurality of update lines, each update line including a plurality of sub-pixels, wherein the first and second sub-pixels are disposed in a first update line and a second update line, respectively, the plurality of update lines being updated in predetermined scanning order, such that the update of the first update line occurs before the update of the second update line in the scanning order.

16. The apparatus of claim 15, wherein the pre-charging system further applies the first voltage to a third pixel electrode of a third sub-pixel, the second and third sub-pixels being updated in different blocks of update lines in the scanning order, such that the first voltage is applied concurrently to the second and third pixel electrodes.

17. A non-transitory computer-readable storage medium storing computer-readable instructions that, when executed by a computing device, cause the device to perform a method of updating an image displayed by a display screen in a first image frame, the display screen including a plurality of sub-pixels including a first sub-pixel with a first pixel electrode and a second sub-pixel with a second pixel electrode, the second sub-pixel being disposed adjacent to the first sub-pixel, the method comprising:

applying a first voltage to the second pixel electrode;

updating the first pixel electrode to a first target voltage value corresponding to a first luminance of the first sub-pixel by applying a second voltage to the first pixel electrode, the second voltage being applied after the application of the first voltage;

updating the second pixel electrode to a second target voltage value corresponding to a second luminance of the second sub-pixel by applying a third voltage to the second pixel electrode, the third voltage being applied after the application of the second voltage; and

applying the first voltage to a third pixel electrode of a third sub-pixel concurrently with the application of the first voltage to the second pixel electrode.

18. The non-transitory computer-readable storage medium of claim 17, wherein applying the first voltage concurrently to the second and third pixel electrodes includes connecting the second and third pixel electrodes to a data line and applying the first voltage to the data line.

19. The non-transitory computer-readable storage medium of claim 18, wherein the display screen includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes transmitting a first start frame pulse through the gate driver chain at a first time, and transmitting a second start frame pulse through the gate driver chain at a second time, such that the second gate driver receives the first start frame pulse and the third gate driver receives the second start frame pulse concurrently.

20. The non-transitory computer-readable storage medium of claim 18, wherein the display screen includes a first gate driver connected to a first transistor of the first sub-pixel, a second gate driver connected to a second transistor of the second sub-pixel, and a third gate driver connected to a third transistor of the third sub-pixel, the first, second, and third gate drivers being included in a gate driver chain, wherein connecting the second and third pixel electrodes to the data line includes the third gate driver switching on the third transistor in response to receiving a first start frame pulse through the gate driver chain, and the second gate driver switching on the second transistor in response to receiving a second start frame pulse through a transmission path that is in parallel to the gate driver chain.

21. The non-transitory computer-readable storage medium of claim 20, wherein connecting the second and third pixel electrodes to the data line further includes transmitting a single start frame pulse, the single start frame pulse being split into the first start frame pulse on the gate driver chain and the second start frame pulse on the parallel transmission path.

22. The non-transitory computer-readable storage medium of claim 21, wherein the method further comprises applying the first voltage to a third pixel electrode of a third sub-pixel, the second and third sub-pixels being updated in different blocks of update lines in the scanning order, such that the first voltage is applied concurrently to the second and third pixel electrodes.