LCD Backlight Duty Ratio Adjustment for Viewing Angle Color Accuracy
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Solution Overview
Problem
Liquid crystal display panels suffer from significant color distortion when viewed from the side, particularly in black and white driving modes, leading to impaired display quality due to variations in transmissivity of red, green, and blue LEDs with the angle of view.
Innovation Solution
A liquid crystal display device and driving method that include a timing controller to calculate and store average brightness values, and an LED brightness controlling unit generating brightness control signals with adjusted duty ratios for red, green, and blue LEDs to mitigate color variation by adjusting the light output based on the angle of view in white or black modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a liquid crystal display panel is used in white or black driving mode, then the display can achieve high brightness and good contrast, but severe color distortion occurs when viewed from the side due to transmissivity variation with angle of view
Solution Approach 1:
The patent applies local quality by adjusting the brightness of individual LED sub-pixels (red, green, blue) differently based on their specific transmissivity characteristics at various viewing angles. The microcontroller calculates and applies unique brightness correction values to each color channel to compensate for angle-dependent transmissivity variations, thereby maintaining color accuracy across different viewing positions while preserving high brightness performance.
2Illumination intensity
If the light output of LEDs is increased to improve brightness, then the display becomes brighter, but color distortion becomes more intensive due to greater variation in transmissivity with angle of view
Solution Approach 1:
The patent implements preliminary anti-action by pre-calculating and applying brightness correction values to counteract the expected color distortion before it occurs. The microcontroller stores transmissivity data and uses it to determine appropriate brightness adjustment values for each LED sub-pixel, thereby preemptively compensating for angle-dependent transmissivity variations and preventing color distortion from becoming intensive even at high brightness levels.
3Manufacturing precision
If a memory unit is added to store average brightness values and transmissivity data, then color variation can be compensated, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the microcontroller to perform multiple functions: it calculates average brightness values from display data, retrieves transmissivity data from the memory unit, determines brightness correction values for each LED sub-pixel, and controls the LED drivers. This multi-functional approach consolidates what could be separate complex subsystems into a single integrated controller, thereby achieving color consistency compensation while minimizing the increase in overall device complexity.
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 effectively reduces color variation with the angle of view, eliminating the reddish appearance in black mode and ensuring consistent color representation across viewing angles, thereby enhancing the display quality of liquid crystal display panels.
Implementation Method 1
applying an electric field to liquid crystals having an anisotropic dielectric between two substrates and controlling intensity of the electric field to control a quantity of light passing through the substrate
Implementation Method 2
applying an electric field to liquid crystals having an anisotropic dielectric between two substrates
Implementation Method 3
a light source unit including red, green, blue LEDs; and a light source driving unit including an LED brightness controlling unit for generating a brightness control signal having a duty ratio according to the average brightness value
Data Source
AI summary
The method of driving a liquid crystal display device includes calculating a brightness average value of pixel data of at least one frame period supplied to a liquid crystal display panel, and storing the average to a memory unit; generating a brightness control signal having a duty ratio according to the brightness average value of the pixel data adjusted taking variation of transmissivity with an angle of view into account in a white or black driving mode of the liquid crystal display panel; and supplying the brightness control signal to a light source unit.