Display Device White Sub-Pixel Threshold Voltage Compensation
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Solution Overview
Problem
The degradation of white light emitting elements in display devices leads to luminance deviation, causing image sticking and deteriorating image quality, which affects the reliability and lifespan of these devices.
Innovation Solution
A display device with a threshold voltage sensor and data compensation unit that senses the threshold voltage of white light emitting elements, calculates an initial white gain, and converts excess gain into red, green, and blue gains to compensate for degradation, thereby reducing stress and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the driving current of white light emitting elements is increased to compensate for degradation, then the luminance can be maintained, but the stress on the elements increases and reliability deteriorates
Solution Approach 1:
The patent changes the driving parameter from increasing white light emitting element current to adjusting RGB sub-pixel gains. By modifying the gain parameters of red, green, and blue sub-pixels instead of increasing white element current, the system maintains luminance compensation while avoiding additional stress on degraded white elements.
Solution Approach 2:
The patent segments the white light emission into its constituent RGB color channels. Instead of treating white light emitting elements as a single unit and increasing their current, the system separately adjusts the gain of individual red, green, and blue sub-pixels to achieve overall white luminance compensation without overloading any single element.
2Manufacturing precision
If the initial white gain is increased to compensate for threshold voltage variation, then the luminance deviation can be corrected, but the excess gain causes image sticking
Solution Approach 1:
The patent changes the compensation approach by converting excess white gain into adjusted RGB gains. Instead of applying a high white gain directly that causes image sticking, the system transforms this into moderated red, green, and blue gains that achieve luminance uniformity without creating the harmful effects of excessive white element driving.
Solution Approach 2:
The patent converts the potentially harmful excess white gain into beneficial RGB sub-pixel adjustments. By transforming the excess gain into separate color channel gains, the system turns what would be a harmful over-driving condition into a beneficial luminance compensation mechanism that avoids image sticking.
3Illumination intensity
If the driving current is increased to maintain luminance, then the image quality can be maintained, but the color temperature becomes distorted
Solution Approach 1:
The patent changes the control strategy from uniform current increase to selective gain adjustment across RGB channels. By independently adjusting the gain parameters of red, green, and blue sub-pixels rather than uniformly increasing current, the system maintains luminance while preserving accurate color temperature.
Solution Approach 2:
The patent applies different gain values to different color channels (red, green, blue) based on their specific characteristics and degradation patterns. This localized adjustment of quality parameters for each color channel allows luminance maintenance while preserving the natural color temperature, unlike uniform current increase which distorts color balance.
Data Source
AI summary
The display device also includes a threshold voltage sensor configured to sense a threshold voltage of a white light emitting element included in the white sub-pixel, a data compensation unit configured to correct data signal depending on a variation in the threshold voltage and generate compensated data signal and a data driver configured to generate a data voltage according to the compensated data signal and output the data voltage to the display panel. The data compensation unit calculates an initial white gain depending on the variation in the threshold voltage. Therefore, the lifetime of the display device can be improved.