LED Backlight Compensation for Illumination Uniformity
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Solution Overview
Problem
Backlight elements in displays, such as LEDs, can experience sub-par efficiency or failure over time, leading to uneven illumination and image quality issues, which existing calibration methods struggle to consistently maintain.
Innovation Solution
A method is implemented to identify sub-par light sources by analyzing light detection values or color/hue shifts, and additional driving is applied to surrounding LEDs in a geometric or non-geometric pattern to compensate for the deficiency, ensuring uniform illumination and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If additional driving is applied to surrounding light sources to compensate for sub-par LEDs, then illumination uniformity is improved, but energy consumption increases
Solution Approach 1:
The patent applies local quality by providing non-uniform driving signals to different light sources based on their specific performance characteristics. Each light source receives a customized drive level tailored to its efficiency, allowing compensation for sub-par LEDs without unnecessarily increasing energy consumption across the entire array. This localized approach optimizes illumination uniformity while minimizing overall energy usage.
Solution Approach 2:
The system dynamically adjusts the drive level parameter for each light source based on measured performance data. By changing the electrical parameters (current, voltage, or PWM duty cycle) applied to individual light sources, the system compensates for efficiency variations and maintains uniform illumination output without proportionally increasing total energy consumption.
2Manufacturing precision
If backlight elements are calibrated during post-factory phase to have uniform brightness, then manufacturing precision is improved, but the system becomes vulnerable to age-related degradation and defective elements
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual light output of each backlight element and using this information to dynamically adjust drive levels. This closed-loop system detects deviations from uniform illumination caused by aging or defects and automatically compensates by modifying the driving signals, thereby maintaining reliability and performance consistency over time despite initial calibration uniformity.
Solution Approach 2:
The system transitions from static factory calibration to dynamic operational adjustment. Drive levels for each light source are continuously or periodically modified based on real-time performance measurements, allowing the system to adapt to aging effects and component variations that occur after manufacturing, thus maintaining long-term reliability.
3Ease of operation
If all LEDs are driven at the same PWM value to maintain calibration, then ease of operation is improved, but sub-par LEDs cause visible defects and non-uniform illumination
Solution Approach 1:
The patent segments the backlight array into individually controllable light sources, each capable of receiving distinct drive signals. This segmentation allows the system to apply uniform PWM control to most LEDs while providing customized compensation signals only to sub-par elements, thereby maintaining both operational simplicity and illumination uniformity.
Solution Approach 2:
By applying local quality principles, the system maintains simple uniform control for the majority of properly functioning LEDs while providing localized customized drive levels only to sub-par elements. This approach preserves ease of operation for normal operation while eliminating visible defects through targeted local adjustments.
Data Source
AI summary
LEDs near or surrounding a non-functional or sub-par LED are adjusted to compensate the sub-par LED. The compensation may include illumination (e.g., increased illumination of nearby LEDs to compensate for under illumination of a non-functional LED) or a shift in hue of the nearby LEDs to compensate for an opposite shift in hue of the sub-par LED.