Organic light emitting diode display pixel crosstalk compensation

• US 10,714,020 B1
• Filed: 10/17/2017
• Issued: 07/14/2020
• Est. Priority Date: 10/17/2017
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Zhang, Rui
• Primary Examiner(s): Chatly, Amit
• Application Number:
  US15/786,226
• Time in Patent Office: 1,001 Days
• 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 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements

Abstract

A portion of an image frame of video content is received and a grey level total of the portion of the image frame is calculated. A grey level offset value corresponding to the grey level total is determined. The grey level offset value corresponds to a pixel portion of an Organic Light Emitting Diode (OLED) display that will display the portion of the image frame. Compensated pixel grey levels are generated by adjusting individual pixel grey levels using the grey level offset value. The compensated pixel grey levels are driven onto the pixel portion of the OLED display.

Claims

1. A computer-implemented method of reducing display pixel crosstalk, the method comprising:

receiving a portion of an image frame of video content;

calculating a grey level total of the portion of the image frame prior to displaying the image frame, wherein the portion of the image frame is a line of the image frame that is a pixel row or pixel column of the image frame, and wherein the grey level total is a summing of digital grey levels of the line of the image frame of a digital image;

determining a grey level offset value corresponding to the grey level total, wherein the grey level offset value corresponds to a pixel portion of an Organic Light Emitting Diode (OLED) display that will display the portion of the image frame, and wherein the pixel portion is a pixel line of the OLED display having pixels that share a voltage supply rail;

generating compensated pixel grey levels for the portion of the image frame of video content, wherein generating the compensated pixel grey levels includes adjusting individual pixel grey levels of the line of the image frame based at least in part on the grey level offset value; and

driving the compensated pixel grey levels onto the pixel line of the OLED display, wherein generating compensated pixel grey levels for the portion of the image frame of the video content is at least partially based on the digital grey levels of the line of the image frame of the digital image, prior to driving the compensated pixel grey levels onto the pixel line of the OLED display to render the line of the image frame of the digital image on the OLED display.

2. The computer-implemented method of claim 1, wherein the compensated pixel grey levels are driven onto the pixel portion of the OLED display for a low persistence time period that is less than a frame time allocated to the image frame.

3. The computer-implemented method of claim 2, wherein the compensated pixel grey levels are driven onto the pixel portion of the OLED display for the low persistence time period as part of a rolling shutter.

4. The computer-implemented method of claim 1, wherein determining the grey level offset value includes querying a look-up-table that includes the grey level offset value that corresponds to the grey level total, the grey level offset value calibrated from light measurements of the pixel portion of the OLED display being illuminated.

5. The computer-implemented method of claim 1 further comprising:

receiving a second portion of the image frame of the video content subsequent to receiving the portion of the image frame, wherein the second portion of the image frame is a same size as the portion of the image frame;

calculating a second grey level total of the second portion of the image frame;

determining a second grey level offset value corresponding to the second grey level total, wherein the second grey level offset value corresponds to a second pixel portion of the OLED display that will display the second portion of the image frame;

generating second compensated pixel grey levels, wherein generating the second compensated pixel grey levels includes adjusting second individual pixel grey levels of the second portion of the image frame based at least in part on the second grey level offset value; and

driving the second compensated pixel grey levels onto the second pixel portion of the OLED display subsequent to driving the compensated pixel grey levels onto the pixel portion of the OLED display.

6. The computer-implemented method of claim 1, wherein the portion of the image frame includes the individual pixel grey levels of the portion of the image frame, and wherein calculating the grey level total includes summing the individual pixel grey levels for each pixel in the portion of the image frame.

7. The computer-implemented method of claim 1, wherein generating the compensated pixel grey levels includes adding the grey level offset value to the individual pixel grey levels.

8. The computer-implemented method of claim 1, wherein the portion of the image frame is received from a graphics processing unit (GPU) and stored in a buffer memory.

9. A Head Mounted Display (HMD) comprising:

an organic light emitting diode (OLED) display;

a graphics processing unit (GPU);

a buffer memory configured to receive a portion of an image frame of video content from the GPU;

an aggregation engine configured to generate a grey level total of the portion of the image frame stored in the buffer memory prior to displaying the image frame, wherein the portion of the image frame is a line of the image frame that is a pixel row or pixel column of the image frame, and wherein the grey level total is a summing of digital grey levels of the line of the image frame of a digital image;

an offset engine configured to generate a grey level offset value in response to receiving the grey level total, wherein the grey level offset value corresponds to a pixel portion of the OLED display that will display the portion of the image frame, and wherein the pixel portion is a pixel line of the OLED display having pixels that share a voltage supply rail; and

a compensation engine configured to receive the line of the image frame of video content from the GPU and configured to receive the grey level offset value from the offset engine, wherein the compensation engine is configured to generate compensated pixel grey levels for individual pixels in the pixel line of the OLED display based at least in part on the grey level offset value and at least in part based on the digital grey levels of the line of the image frame of the digital image, prior to the line of the image frame of the digital image being rendered on the OLED display, wherein the compensation engine is further configured to provide the compensated pixel grey levels to the OLED display to enable rendering of the line of the image frame of the digital image.

10. The HMD of claim 9, wherein the buffer memory is configured to receive a low persistence duty cycle signal for updating the buffer memory, and wherein the low persistence duty cycle signal is driven according to a rolling shutter that updates the OLED display.

11. The HMD of claim 9, wherein the offset engine is configured to query a look-up-table to generate the grey level offset value, wherein each table grey level total in the look-up-table has a corresponding table grey level offset value in the look-up-table calibrated from light measurements of the pixel portion of the OLED display.

12. The HMD of claim 9, wherein the OLED display includes a driver integrated-circuit configured to receive the compensated pixel grey levels and drive the compensated pixel grey levels on the pixel portion of the OLED display.

13. The HMD of claim 12, wherein the driver integrated-circuit is configured to drive the compensated pixel grey levels on the pixel portion of the OLED display for a low persistence time that is less than a frame time allocated to the image frame.

14. A device comprising:

an organic light emitting diode (OLED) display;

a computer-readable medium including a look-up-table including a plurality of table grey level offset values corresponding to table grey level totals for a plurality of pixel portions of the OLED display, the plurality of table grey level offset values being specifically calibrated for the plurality of pixel portions of the OLED display;

a buffer memory configured to receive digital grey levels of a portion of an image frame of video content prior to displaying the image frame, wherein the portion of the image frame is a line of the image frame that is a pixel row or pixel column of the image frame of a digital image;

an aggregation engine configured to generate a grey level total of the portion of the image frame by summing the digital grey levels of the line of the image frame in the buffer memory;

an offset engine configured to query the look-up-table for a grey level offset value of the plurality of table grey level offset values that corresponds to the grey level total, wherein the grey level offset value corresponds to a pixel portion of the plurality of pixel portions of the OLED display that will display the portion of the image frame, and wherein the pixel portion is a pixel line of the OLED display having pixels that share a voltage supply rail; and

a compensation engine configured to receive the line of the image frame and configured to generate compensated pixel grey levels for individual pixels in the pixel line of the OLED display based at least in part on the grey level offset value and at least in part based on the digital grey levels of the line of the image frame in the digital image, prior to the line of the image frame of the digital image being rendered on the OLED display, to enable a compensated rendering of the line of the image frame of the digital image on the OLED display.

15. The device of claim 14, wherein the buffer memory is configured to receive a low persistence duty cycle signal for updating the buffer memory, and wherein the low persistence duty cycle signal is driven according to a rolling shutter that updates the OLED display.

16. The device of claim 14, wherein the plurality of table grey level offset values is calibrated from light measurements of the plurality of pixel portions of the OLED display.