Color and Luminance Compensation for Large AMOLEDs

Many well-known pixel compensation circuits have been applied to control TFT $V_{th}$ variations on small size AMOLED panels. For large (>30-inch) AMOLEDs, luminance and color uniformity are affected by TFT variations, but also by ELVDD IR drop and cavity non-uniformity which are not easily compensated by in-pixel circuits. AMOLED panels may also suffer from manufacturing-induced mura. An external compensation method based on optical measurements is proposed and applied to large AMOLED panels. It improves luminance uniformity by up to 95% at 200nits and color uniformity by up to 99% (${\Delta}$u'v' <0.004) on large AMOLED panels, and provides-increased margin against processinduced mura.