OFFSETTING MULTIPLE COUPLING EFFECTS IN DISPLAY SCREENS

• US 20120299972A1
• 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
• Granted Patent: US 8,502,842 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2300/04 Structural and physical details of display devices
• CPC Class Codes: G09G 2310/02 Addressing, scanning or driving the display screen or processing steps related thereto
• 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 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 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

Design criteria of display screens is provided that can be used in combination with particular inversion schemes and scanning orders of the display screens to reduce or eliminate visual artifacts that can be caused by the effects of capacitive coupling of voltage changes in one part of the display into other parts of the display. Using particular combinations of inversion schemes and scanning orders, together with particular design criteria for the display screen, can allow one type of effect, e.g., an increase or decrease in a brightness of a display pixel, caused by one type of coupling effect, such as a coupling between data lines, can be offset by the effect caused by another type of coupling effect, such as a coupling between pixel electrodes.

Claims

1. A display screen comprising:

a plurality of scanning lines, each scanning line including a plurality of display pixels, each display pixel including a plurality of sub-pixels, each sub-pixel including a pixel electrode, the scanning lines arranged such that a pixel-to-pixel capacitance exists between adjacent ones of the pixel electrodes in scanning lines, each pixel-to-pixel capacitance having a predetermined first capacitance value;

a plurality of data lines arranged such that a data-to-data capacitance exists between adjacent ones of the data lines, each data-to-data capacitance having a predetermined second capacitance value;

a scanning system that scans the scanning lines to update data voltages on the pixel electrodes in a scanning order of the scanning lines, the updating of the pixel electrodes in each scanning line including electrically connecting the pixel electrodes in each of the display pixels in the scanning line to a corresponding set of the data lines, applying a target data voltage to each data line in each of the sets of data lines in a predetermined sequence while the data lines corresponding to the other of the data lines in each set of the data lines are electrically floating, wherein a polarity of each of the target data voltages is determined by the scanning system according to a predetermined inversion scheme,

wherein each application of target data voltage in a plurality of the applications of target data voltages results in a first error in a brightness of one or more sub-pixels based on a coupling of the corresponding application of target data voltage through one of the pixel-to-pixel capacitances, the first error being based on one of an increase in a magnitude of a voltage on the corresponding pixel electrode and a decrease in the magnitude of the voltage on the corresponding pixel electrode, the increase or decrease being based on the first capacitance value,

wherein each application of target data voltage in a plurality of the applications of target data voltages results in a second error in a brightness of one or more sub-pixels based on a coupling of the corresponding application of target data voltage through one of the data-to-data capacitances, the second error being based on one of an increase in a magnitude of a voltage on the corresponding pixel electrode and a decrease in the magnitude of the voltage on the corresponding pixel electrode, the increase or decrease being based on the second capacitance value,

wherein the first and second errors offset each other in one or more of the sub-pixels.

2. The display screen of claim 1, wherein the offset of the first and second errors includes one of a cancelation of the first and second errors in a single sub-pixel, a uniform increase in brightness of a plurality of the sub-pixels, and a uniform decrease in brightness of a plurality of the sub-pixels.

3. The display screen of claim 1, wherein the lines of display pixels are arranged in rows.

4. The display screen of claim 1, wherein the inversion scheme includes a 2-dot inversion scheme, the scanning order includes a scanning order of updating scanning lines sequentially in order of scanning line position.

5. The display screen of claim 4, wherein first capacitance value is a first capacitance ratio of a first mutual capacitance and a first self-capacitance, the second capacitance value is a second capacitance ratio of a second mutual capacitance and a second self-capacitance, and the second capacitance ratio is approximately twice the first capacitance ratio.

6. The display screen of claim 1, wherein the inversion scheme includes a 4-dot inversion scheme, the scanning order includes a scanning order of updating scanning lines of a plurality of blocks of eight adjacent scanning lines in an order within each block of second scanning line, first scanning line, fourth scanning line, third scanning line, sixth scanning line, fifth scanning line, eighth scanning line, and seventh scanning line.

7. The display screen of claim 6, wherein first capacitance value is a first capacitance ratio of a first mutual capacitance and a first self-capacitance, the second capacitance value is a second capacitance ratio of a second mutual capacitance and a second self-capacitance, and the second capacitance ratio is approximately twice the first capacitance ratio.

8. The display screen of claim 1, wherein the one of the first and second errors includes an average brightness error over a plurality of sub-pixels.

9. The display screen of claim 8, wherein the average brightness error over the plurality of sub-pixels includes an average brightness error over sub-pixels in a single display pixel.

10. The display screen of claim 1, the display screen incorporated within a computing system.

11. The display screen of claim 10, wherein the computing system includes one of a mobile telephone and a digital media player.

12. A method of scanning a display screen, the method comprising:

scanning a plurality of scanning lines of the display screen to update data voltages on pixel electrodes in sub-pixels of each scanning line in a scanning order of the scanning lines, the updating of the pixel electrodes in each scanning line including electrically connecting the pixel electrodes in each of a plurality of display pixels in the scanning line to a corresponding set of a plurality of data lines, applying a target data voltage to each data line in each of the sets of data lines in a predetermined sequence while the data lines corresponding to the other of the data lines in each set of the data lines are electrically floating, wherein a polarity of each of the target data voltages is determined by the scanning system according to a predetermined inversion scheme,

wherein the inversion scheme includes a 4-dot inversion scheme, the scanning order includes a scanning order of updating scanning lines of a plurality of blocks of eight adjacent scanning lines in an order within each block of second scanning line, first scanning line, fourth scanning line, third scanning line, sixth scanning line, fifth scanning line, eighth scanning line, and seventh scanning line.

13. 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 scanning a display screen, the method comprising:

scanning a plurality of scanning lines of the display screen to update data voltages on pixel electrodes in sub-pixels of each scanning line in a scanning order of the scanning lines, the updating of the pixel electrodes in each scanning line including electrically connecting the pixel electrodes in each of a plurality of display pixels in the scanning line to a corresponding set of a plurality of data lines, applying a target data voltage to each data line in each of the sets of data lines in a predetermined sequence while the data lines corresponding to the other of the data lines in each set of the data lines are electrically floating, wherein a polarity of each of the target data voltages is determined by the scanning system according to a predetermined inversion scheme,

wherein the inversion scheme includes a 4-dot inversion scheme, the scanning order includes a scanning order of updating scanning lines of a plurality of blocks of eight adjacent scanning lines in an order within each block of second scanning line, first scanning line, fourth scanning line, third scanning line, sixth scanning line, fifth scanning line, eighth scanning line, and seventh scanning line.