Chromaticity Correction for Display Backlight Luminance Shift
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Solution Overview
Problem
Display devices with backlights experience luminance degradation and chromaticity shift over time, making it difficult to accurately measure and correct chromaticity without user intervention, as the backlight driving level and temperature conditions differ from the reference state.
Innovation Solution
A chromaticity correction device that includes a luminance detection unit, backlight driving level detection, temperature detection, and a reference luminance calculation unit to estimate a reference luminance value based on measurable backlight temperature and driving level, allowing for real-time chromaticity correction of video signals by calculating a chromaticity correction value from estimated white point chromaticity and target white point chromaticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the backlight luminance value is detected under reference state conditions (specific temperature and driving level), then the chromaticity correction value can be calculated accurately, but the user must stop the display device and manually measure the luminance, which burdens the user and interrupts usage
Solution Approach 1:
The display device automatically performs chromaticity correction without user intervention. The system uses built-in sensors to detect backlight luminance, temperature, and driving level, then automatically calculates and applies correction values through the chromaticity correction circuit, eliminating the need for manual measurement and user-stop procedures
Solution Approach 2:
The system pre-stores reference luminance values and correction characteristics in memory. When correction is needed, the system retrieves appropriate reference data and automatically performs the correction calculation and application, eliminating the need for real-time manual measurement and user intervention
2Ease of operation
If the backlight luminance value is detected at arbitrary driving levels during normal use, then the display device remains operational without interruption, but the detected luminance value cannot be accurately compared with reference state values due to different operating conditions
Solution Approach 1:
The system detects multiple parameters including backlight luminance, temperature, and driving level simultaneously. It then adjusts and normalizes these parameters to reference state conditions through calculation, enabling accurate chromaticity correction while maintaining arbitrary driving levels during normal operation
Solution Approach 2:
The system introduces temperature and driving level as intermediary parameters that mediate between the actual operating conditions and the reference state. By detecting and compensating for these intermediary parameters, the system can accurately compare luminance values across different operating conditions
3Productivity
If the display device continuously monitors backlight luminance and temperature during operation, then real-time chromaticity correction is enabled, but additional detection circuits and processing requirements increase device complexity
Solution Approach 1:
The detection circuits perform multiple functions: they detect backlight luminance for chromaticity correction, monitor temperature for compensation calculations, and track driving level for normalization. This multi-functionality reduces the need for separate dedicated circuits for each measurement
Solution Approach 2:
The system continuously monitors backlight luminance and temperature, compares them against reference values, and automatically adjusts chromaticity correction values through feedback control. This closed-loop feedback enables real-time correction while using efficient comparison and calculation circuits
Data Source
AI summary
A chromaticity correction device corrects chromaticity of a video signal displayed on a display panel of a display device to correspond to a change in a luminance value of the display panel. The chromaticity correction device includes a luminance detection unit which detects the luminance value, a backlight driving level detection unit which detects a backlight driving level, a temperature detection unit which detects an internal device temperature or an ambient temperature, a reference luminance value calculation unit which estimates a reference luminance value in a characteristic of an initial state, a chromaticity calculation unit which obtains a chromaticity change amount of white point chromaticity and estimated white point chromaticity that is an estimated value of current white point chromaticity, a chromaticity correction value calculation unit which obtains a chromaticity correction value and a chromaticity correction circuit which corrects the chromaticity of the video signal.