Alternating Polarity Driving for OLED Threshold Voltage Compensation
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Solution Overview
Problem
Organic light emitting displays face challenges in efficiently driving sub-pixels to achieve optimal light emission and threshold voltage compensation, leading to variations in driving characteristics and display quality.
Innovation Solution
A method of driving an organic light emitting display by alternately outputting positive and negative data signals and scan signals, dividing the horizontal period in half, and using dual pixel circuits to manage the polarity and emission states of sub-pixels, thereby improving design freedom and compensating for threshold voltage during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single polarity data signaling is used, then the circuit design is simpler, but the display quality and lifetime are reduced due to threshold voltage variations
Solution Approach 1:
The patent implements alternating positive and negative data signals in a periodic manner, where the data driver switches between positive voltage polarity and negative voltage polarity at regular intervals. This periodic action allows the organic light emitting element to operate under different polarity conditions, compensating for threshold voltage shifts and improving display quality and lifetime without requiring complex additional hardware circuits.
Solution Approach 2:
The patent changes the voltage polarity parameter of the data signal from fixed to variable. By dynamically switching between positive and negative voltage levels, the system adapts to threshold voltage variations in the organic light emitting element, thereby improving reliability and display performance while maintaining a relatively simple driving circuit architecture.
2Measurement precision
If alternating positive and negative data signals are used, then threshold voltage compensation is improved, but the signal generation complexity increases
Solution Approach 1:
The data driver is designed to perform multiple functions: it generates both positive and negative data signals, controls the scanning process, and compensates for threshold voltage variations. By making the data driver multi-functional, the patent achieves accurate threshold voltage compensation without adding separate dedicated circuits for each function, thus improving measurement precision while controlling signal generation complexity.
Solution Approach 2:
The alternating polarity signal generation follows a periodic pattern where positive and negative data signals are generated in alternating time periods. This periodic structure simplifies the signal generation logic compared to arbitrary waveforms, as the driver only needs to implement regular polarity switching based on timing signals, thereby achieving accurate threshold voltage compensation with manageable complexity.
3Device complexity
If the horizontal period is divided into two half periods, then the alternating signal generation is simplified, but the time for complete signal cycle increases
Solution Approach 1:
The horizontal period is divided into two equal half periods for generating positive and negative data signals respectively. This periodic division simplifies the signal generation logic by creating regular, predictable timing patterns that are easier to implement in the data driver circuitry, even though it extends the total horizontal period compared to single-polarity signaling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the display quality and lifetime of organic light emitting displays by effectively managing sub-pixel emission and threshold voltage compensation, reducing variations in driving characteristics and improving the overall performance.
Implementation Method 1
An organic light emitting element used for an organic light emitting display is a self-emitting element having a light emitting layer formed between two electrodes thereof
Data Source
AI summary
Provided is an organic light emitting display for improving the display quality and lifetime, the organic light emitting display includes a display panel comprising sub pixels disposed at intersections of data lines and first and second scan lines; a data driver alternately outputting a positive data signal and a negative data signal to the data lines; and a scan driver respectively outputting a first scan signal and a second scan signal to the first scan lines and the second scan lines.