Chroma Compensated LED Backlight Display
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Solution Overview
Problem
Existing backlights, particularly fluorescent lamp backlights, face challenges such as high driving voltage requirements, complexity in dimming and color adjustment, and fragility, which are unsuitable for applications needing mechanical ruggedness and user-adjustable luminescence and chrominance.
Innovation Solution
A backlit display system utilizing a matrix of LEDs of different colors, optically coupled sensors, and a feedback controller to regulate luminance and chrominance, allowing for variable light output by adjusting drive current based on sensor feedback and chrominance parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluorescent lamp backlights are used, then effective illumination is achieved, but driving voltage requirement increases and mechanical fragility worsens
Solution Approach 1:
The patent replaces fluorescent lamp backlights with LED backlight modules, substituting a mechanical/thermal light source with a solid-state electronic light source. This eliminates the fragile glass components and filaments of fluorescent lamps while maintaining effective illumination through multiple LED groups arranged in a modular configuration.
Solution Approach 2:
The backlight is divided into multiple independent LED groups (first group, second group, third group, etc.), each containing LEDs of different colors. This segmentation allows individual groups to be controlled separately, improving reliability by isolating potential failure points while collectively providing robust illumination.
2Illumination intensity
If fluorescent lamp backlights are used, then illumination is provided, but device complexity increases for dimming and color adjustment
Solution Approach 1:
The patent implements dynamic control of LED groups through independent dimming circuits and color adjustment mechanisms. Each LED group can be individually dimmed or brightened, and the color temperature can be dynamically adjusted by varying the intensity of different colored LED groups, providing flexible illumination control without complex mechanical shutters.
Solution Approach 2:
The system adjusts illumination characteristics by changing electrical parameters (current, voltage) to individual LED groups rather than using mechanical adjustments. By varying the drive current to different colored LED groups, the system achieves color temperature adjustment and dimming through electronic parameter control, simplifying the overall device structure.
3Illumination intensity
If fluorescent lamp backlights are used, then light output is achieved, but chrominance and luminescence adjustment capability is lost
Solution Approach 1:
Different regions (LED groups) of the backlight have different color characteristics (warm white, cool white, etc.). Each group maintains its specific color quality while being independently controllable, allowing the system to achieve various chrominance and luminescence combinations by activating specific groups or adjusting their individual intensities.
Solution Approach 2:
The LED groups are designed to serve multiple functions: they can be individually controlled for dimming, combined to achieve different color temperatures, and adjusted to provide various chrominance and luminescence levels. This multi-functionality allows a single backlight module to replace multiple specialized lighting 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 system provides a simple, rugged, and reliable method for varying luminescence and chrominance without mechanical parts, effectively addressing the limitations of traditional backlights by ensuring consistent and adjustable light output.
Implementation Method 1
The backlight is formed from i groups of LEDs of different colors
Implementation Method 2
one or more sensors optically coupled to the LEDs, a controller receiving signals Si from the sensors
Implementation Method 3
The combined light produced by the LEDs is directed to the transmissive LCD preferably through a diffusing layer
Data Source
AI summary
Methods and apparatus are provided for a backlit display with variable luminance and chrominance. The apparatus comprises i groups of LEDs of different colors and one or more sensors optically coupled to the LEDs. The combined light produced by the LEDs is directed to a transmissive liquid crystal display, preferably through a diffusing layer. The sensors monitor the output Si of each group of LEDs. Si for each group of LEDs is multiplied by a chrominance determining parameter Ki to obtain Ki*Si which is then compared to a commanded luminance signal LC to obtain LC−Ki*Si, which difference is used to adjust the drive current to each group of LEDs to achieve LC with the desired chrominance set by Ki. By changing Ki and LC the chrominance and luminescence of the display may be varied and aging effects compensated.