Backlight Correction Map for LCD Color Uniformity
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Solution Overview
Problem
LCD displays face challenges with color and brightness non-uniformity due to variations in LED aging and manufacturing, leading to decreased performance and increased costs, as existing solutions primarily focus on backlight panel adjustments rather than addressing viewer-observed non-uniformities in Liquid Crystal (LC) panels.
Innovation Solution
A method and system that measure physical outputs from the display to create correction maps for pixel values, using image generators, capture devices, and processors to adjust both backlight source and LC modulators, applicable to various light sources including LEDs, CCFLs, and Laser Diodes, ensuring uniformity across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED backlighting is used to replace CCFL, then energy consumption is reduced and lifetime is extended, but color and brightness uniformity deteriorates due to LED aging and manufacturing variations
Solution Approach 1:
The system performs preliminary measurement of the display's actual color and brightness output across multiple zones, then pre-calculates correction values for pixel values before display content is rendered. This allows the system to compensate for LED non-uniformity in advance, ensuring uniform appearance without requiring physical adjustment of LED characteristics.
Solution Approach 2:
The system dynamically adjusts pixel values in the image signal to compensate for LED aging and manufacturing variations. By changing the parameters (brightness and color) of individual pixel zones based on measured non-uniformity characteristics, the system counteracts the deteriorating uniformity caused by LED degradation over time.
2Area of stationary object
If multiple LEDs are used to cover large display areas, then display size is increased, but color and brightness uniformity deteriorates due to variations in individual LED characteristics
Solution Approach 1:
The display area is divided into multiple zones corresponding to different LED backlight regions. The system measures and characterizes non-uniformity in each zone separately, then applies zone-specific correction values to pixel signals. This segmentation approach allows independent compensation for each LED's characteristics, maintaining uniformity across the entire large display area.
3Ease of manufacture
If existing backlight panel adjustments are used, then manufacturing simplicity is maintained, but viewer-observed non-uniformity in LC panels is not addressed
Solution Approach 1:
The system replaces physical/mechanical adjustment of backlight panels with electronic/software-based correction. Instead of mechanically adjusting LED positions or intensities during manufacturing, the system uses computational methods to measure non-uniformity and apply digital corrections to image signals, achieving uniformity without complex mechanical systems.
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
The solution significantly improves color and brightness uniformity, extending the lifespan of displays, reducing costs by tolerating units that would otherwise be discarded, and achieving high uniformity levels, essential for accurate color reproduction and viewer experience.
Implementation Method 1
Light Emitting Diodes (LEDs) are semiconductor diodes made of special material that radiate visible and invisible light (covering infrared to ultraviolet range of electromagnetic spectrum) upon spontaneous recombination of electrons and holes in the p-n junction
Implementation Method 2
A liquid crystal display (LCD), commonly used for TV panels and computer monitors, utilizes the light modulating properties of liquid crystals (LCs). LCs are transmissive elements. They merely guide and do not emit light directly.
Data Source
AI summary
Systems and methods for improving color and brightness uniformity of an image displayed on a backlit LCD are disclosed. In one example, a correction map is computed and applied to the LCD pixel values. In another example, the voltage settings of the backlight source components are also corrected in addition to the LCD pixel values. For efficient hardware implementation, corrections are applied using function representation of a grid data transformation relating measured values to corrected values. In one particular exemplary embodiment, the backlight source is provided by a plurality of LEDs. In another exemplary embodiment, the display consists of a plurality of OLEDs wherein the light source and the display panels coincide.