OLED Display Variable Gamma Reference Voltage Compensation
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Solution Overview
Problem
Existing OLED display devices face image quality degradation due to differences in threshold voltage characteristics between driving transistors, leading to uneven luminance and potential screen stains, as current sensing and compensation methods do not accurately reflect or fully compensate for these changes.
Innovation Solution
An OLED display device with a gamma reference voltage supply circuit, data driver, and timing controller that repeatedly senses and compensates for updated threshold voltages, using digital-to-analog and analog-to-digital converters to provide precise voltage adjustments and corrections, ensuring uniform luminance across subpixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transistor characteristics are sensed and compensated using fixed gamma reference voltages, then initial threshold voltage differences can be compensated, but updated threshold voltage changes over time are not reflected, leading to residual luminance differences and screen stains
Solution Approach 1:
The patent applies dynamics by making the gamma reference voltages variable rather than fixed. The gamma reference voltage supply circuit dynamically adjusts the reference voltages based on the sensing mode (initial threshold voltage sensing vs. updated threshold voltage sensing), enabling the system to adapt to changing transistor characteristics over time and maintain accurate compensation.
Solution Approach 2:
The patent implements periodic action through repeated sensing and compensation operations. The system performs initial threshold voltage sensing, applies compensation, then periodically repeats updated threshold voltage sensing to track and compensate for aging effects, ensuring continuous accuracy throughout the display device's operation.
2Device complexity
If a single gamma reference voltage range is used for both initial sensing and updated sensing, then device complexity is reduced, but measurement precision of threshold voltage changes is insufficient, causing stains on low-grayscale luminance
Solution Approach 1:
The patent applies local quality by providing different gamma reference voltage ranges for different sensing purposes. A first gamma reference voltage range is used for initial threshold voltage sensing, while a second gamma reference voltage range is used for updated threshold voltage sensing. This localized optimization ensures that each sensing operation uses the most appropriate voltage range, improving measurement precision without requiring a completely separate sensing system.
3Productivity
If transistor characteristics are not repeatedly sensed and compensated, then device complexity and operation time are reduced, but luminance uniformity deteriorates over time due to transistor degradation
Solution Approach 1:
The patent implements continuity of useful action by establishing a repeated sensing and compensation cycle that continues throughout the display device's operation. The system performs initial sensing and compensation, then repeatedly performs updated sensing and compensation at different operation times, ensuring that luminance uniformity is continuously maintained despite transistor degradation over time.
Data Source
AI summary
An OLED display device includes an OLED display panel on which subpixels are disposed, a gamma reference voltage supply circuit supplying gamma reference voltages that are variable during driving and when sensing a threshold voltage, and a data driver supplying data voltages based on the gamma reference voltages to data lines. The data driver senses a voltage of a sensing node within each of the subpixels in sensing mode. A timing controller controls the data driver, and performs a compensation process based on the voltage sensed by the data driver.