OLED Timing Controller ADC Error Correction
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Solution Overview
Problem
Existing organic light emitting display devices face issues with luminance uniformity due to variations in threshold voltages and mobility characteristics of driving transistors, which are not accurately compensated for by analog-to-digital converters (ADCs) due to gain and offset errors, leading to deviations in output data between data driving ICs.
Innovation Solution
An organic light emitting display device and method that includes a display panel with pixels connected to gate lines, data lines, and sensing lines, featuring a timing controller that calculates and corrects for gain and offset errors in ADCs to modulate input data, thereby minimizing output deviations and improving luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ADCs are used to sense characteristic changes of driving transistors, then transistor variation compensation is achieved, but output data deviation occurs due to gain and offset errors
Solution Approach 1:
The patent applies preliminary action by measuring and storing gain errors and offset errors of ADCs during a test mode before normal display operation. These error parameters are pre-calculated and saved in memory, then used to correct sensing data during actual pixel driving, thereby compensating for ADC variations without affecting normal display performance
Solution Approach 2:
The patent implements feedback by using the measured gain and offset errors to correct the output data of ADCs. The correction process forms a closed-loop system where the sensing unit continuously monitors transistor characteristics, the timing controller applies error compensation based on stored parameters, and the corrected data drives the pixels, thereby eliminating luminance deviations caused by ADC variations
2Reliability
If sensing units with ADCs are added to each pixel, then transistor characteristic compensation is enabled, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a shared sensing unit structure where ADCs and sensing circuits are commonly used across multiple pixels rather than dedicating separate sensing circuits to each pixel. The sensing unit can selectively sense characteristics of different driving transistors, and the timing controller universally applies correction parameters to all pixels, thereby reducing overall device complexity while maintaining compensation capability
Solution Approach 2:
The patent introduces an intermediary approach by placing the ADC error measurement and correction functionality in the timing controller rather than directly in each pixel circuit. The sensing unit acts as an intermediary between the pixel circuits and the timing controller, transferring sensing data for centralized processing and correction, thereby simplifying the pixel-level circuit design while achieving uniform image quality
Data Source
AI summary
Disclosed is an organic light emitting display device. The organic light emitting display device includes a display panel including a plurality of pixels formed in intersection areas between a plurality of gate lines, a plurality of data lines, and a plurality of sensing lines, a gate driver supplying a gate signal to the gate lines, a plurality of data driving ICs including a data driver, supplying data voltages to the data lines, and a sensing unit including a plurality of ADCs that each sense characteristic change of a driving transistor included in a corresponding pixel to generate sensing data, a memory storing a gain error and offset error of each ADC, and a timing controller correcting the sensing data on a basis of the gain error and offset error, modulating input data on a basis of the corrected sensing data, and supplying the modulated data to the data driving ICs.