AMOLED Driving Circuit Adjusts Current to Compensate LED Decay
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Solution Overview
Problem
Active matrix organic light-emitting diode (AMOLED) displays experience brightness degradation due to material decay, where conventional methods fail to maintain constant brightness as the efficiency of the OLED declines faster than the TFT, leading to uneven brightness across the display and residual images when stationary.
Innovation Solution
A driving circuit with an adjustable reference voltage is introduced, which measures the decay of LED materials and compensates by increasing electric current to maintain original brightness, addressing the decay in OLED efficiency and preventing inter-pixel inconsistencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TFT compensation methods are used to maintain constant electric current, then the threshold voltage shift is compensated, but the OLED brightness still degrades due to efficiency decline
Solution Approach 1:
The patent implements a feedback mechanism where the driving circuit continuously monitors the actual brightness output of the OLED and adjusts the driving current accordingly. This closed-loop control system compensates for OLED efficiency degradation by increasing current when brightness decreases, thereby maintaining constant perceived brightness despite material decay over time.
Solution Approach 2:
The patent dynamically changes the driving current parameter based on OLED efficiency degradation. By adjusting the current level in response to measured brightness output, the system compensates for efficiency loss and maintains constant brightness, directly addressing the limitation of conventional fixed-current approaches.
2Use of energy by stationary object
If the display remains stationary for extended periods, then power consumption is reduced, but brightness degradation accelerates in the displayed areas causing residual images
Solution Approach 1:
The patent applies periodic refresh signaling to pixels that remain stationary for extended periods. This periodic activation, even at low intensity, prevents localized efficiency degradation by periodically resetting the OLED materials in those areas, thereby preventing residual image formation while maintaining overall low power consumption during static display periods.
Solution Approach 2:
The patent implements preliminary compensation measures by detecting early signs of localized degradation and applying preventive current adjustments before significant residual images form. The system proactively addresses potential brightness不均匀ity by adjusting driving currents in anticipation of degradation patterns.
Data Source
AI summary
The present invention provides a driving apparatus, method and system for a light emitting device, suitable for use in an active matrix organic light emitting diode (AMOLED) display, which has an adjustable reference voltage, so as to compensate for degradation in brightness due to LED materials decay.