OLED demura system Color Space Beijing Technology Inc

OLED de-mura system Color Space (Beijing) Technology Inc 2016. 12. 29

OLED mura

OLED screen burn-in mura • Screen burn-in mura is a permanent discoloration of areas on OLED caused by cumulative non-uniform usage of the pixels. • Frequently using APP with no-moving text, graphics and flags can create a permanent ghost-like image mura. • Blue color OLED degradates much faster than green and Red color OLED. Which cause color shift mura after a period of application.

blue color OLED burn-in mura

De-mura System • 2 D matrix Chromameter • De-mura capture and compensation software • Realization circuit

De-mura System • A kind of de-mura system is designed to calibriate not only the screen burn-in mura but also the color shift mura. • The de-mura system includes a signal generation unit, an image pickup unit and a control unit. • The signal generation unit display test pattern on the OLED screen. The image pickup unit including a high resolution 2 D matrix chromameter can capture CIE 1934 XYZ of each OLED pixels and distinguish the uneven light output of each pixels. • The control unit control the enitre system procedure and generate luma correction data to make screen uniform and color correction data to let screen output true color. • Both brightness correction data and color correction data will be compressed and save inside the display memory. Display control circuit uses these correct data to realize de-mura function.

De-mura Realization flow

De-mura system software

De-mura measurement • Capture CIE 1931 2° XYZ of each pixel • Brightness and color calculation: • Brightness=Y • x= X/(X+Y+Z) • y= Y/(X+Y+Z) Brightness accuracy 14 bit; Absolute Brightness: +/- 3%; Repeatability: +/- 0. 5% Absolute color accuracy: 0. 003 ; Repeatability: 0. 0006

Compare of de-mura function （exponential histogram）

9 co-efficiency De-mura realization matrix

True color gamut realization

Color uniformity improvement