Electroluminescence Display Sensing Circuit with Current Tracking
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Solution Overview
Problem
Electroluminescence display apparatuses with active matrix type pixels face luminance deviations due to varying threshold voltages, limiting image implementation and requiring compensation technologies with low noise sensitivity.
Innovation Solution
An electroluminescence display apparatus with a pixel connected to a data line and a reference voltage line, featuring a driving element that generates a driving current based on sensing data voltage and reference voltage, and a comparison and tracking unit that adjusts the sensing data voltage to maintain a target current range, enhancing sensing and compensation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional compensation technology is used, then luminance deviation between pixels can be compensated, but sensing performance is degraded due to noise occurring in sensing process
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage sensing and compensation during the initialization phase before actual image display. The sensing data voltage is applied to sense threshold voltages of driving elements in advance, and compensation values are calculated and stored before the display operation begins. This separates the noisy sensing operation from the precision display operation, allowing compensation to be prepared beforehand without affecting real-time image quality.
Solution Approach 2:
The patent introduces an intermediary approach by using a dedicated sensing operation with specifically designed sensing data voltages that are different from normal display data voltages. This intermediary sensing process allows threshold voltage measurement to be performed in a controlled manner with optimized voltage levels and timing, reducing noise interference while maintaining measurement accuracy.
2Reliability
If threshold voltage sensing is performed with conventional methods, then compensation can be applied, but sensing time is excessive
Solution Approach 1:
The patent implements periodic action by conducting threshold voltage sensing in specific time periods (horizontal blanking periods or vertical blanking periods) rather than continuously. The sensing operation is performed periodically at defined intervals using timing signals to control when sensing data voltages are applied. This periodic timing approach ensures accurate threshold voltage measurement while minimizing the total sensing time and avoiding interference with normal display operations.
Solution Approach 2:
The sensing operation is performed in advance during initialization or in predetermined time slots before display refresh, allowing compensation values to be prepared beforehand. This preliminary sensing approach ensures that threshold voltage compensation is already in place when display operations begin, improving reliability while confining the time-consuming sensing process to non-critical periods.
3Stability of the object's composition
If driving current level is not controlled, then sensing operation is simple, but luminance uniformity across pixels deteriorates
Solution Approach 1:
The patent applies feedback by implementing a comparison and tracking unit that monitors the driving current level during sensing operations and adjusts the sensing data voltage accordingly. The system compares the actual driving current with a target current range and provides feedback control to maintain the current within acceptable limits. This feedback mechanism ensures luminance uniformity across pixels by compensating for variations in driving element characteristics while keeping the sensing operation systematically controlled.
Solution Approach 2:
The patent implements dynamics by making the sensing data voltage adjustable and adaptive rather than fixed. The sensing control circuit dynamically adjusts voltage levels based on real-time measurements of driving element threshold voltages and current levels. This dynamic adjustment allows the sensing operation to adapt to variations across different pixels and operating conditions, maintaining luminance uniformity while managing complexity through systematic control algorithms.
Data Source
AI summary
In an electroluminescence display apparatus and a driving method of an electroluminescence display apparatus, the electroluminescence display apparatus includes a pixel connected to a data line and a reference voltage line, the pixel including a driving element configured to generate a driving current based on a sensing data voltage supplied through the data line and a reference voltage supplied through the reference voltage line, and a level of the driving current being proportional to a level of the sensing data voltage, a comparison and tracking circuit configured to previously determine a target current range between a reference low current and a reference high current and change current tracking data for adjusting a level of the sensing data voltage until the driving current input through the reference voltage line is within the target current range, and a digital-to-analog converter configured to adjust a level of the sensing data voltage so as to be proportional to a size of the current tracking data and supply the level-adjusted sensing data voltage to the data line.