RGBW LCD White Luminance via Selective Chromatic Conversion
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving high luminance without increasing power consumption, particularly in bright image displays, due to chromatic purity degradation when using the RGBW pixel structure, which results in noticeable color degradation and limited applications in actual products.
Innovation Solution
A liquid crystal display device with a level detection circuit and image data conversion circuit that switches between two conversion methods based on input image data levels, using a four-color pixel structure (red, green, blue, and white) to maintain chromaticity and luminance for lower-level data and allow chromatic changes for higher-level data, while controlling backlight emission to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If RGBW pixel structure is used to improve white luminance, then transmittance is improved, but chromatic purity degrades
Solution Approach 1:
The patent applies different conversion methods based on the luminance level of input image data. For high-luminance data (white peak areas), chromatic changes are allowed to maximize luminance improvement. For low-luminance data, chromatic purity is preserved. This local differentiation resolves the contradiction by applying chromatic flexibility only where luminance enhancement is most critical.
Solution Approach 2:
The patent dynamically switches between two conversion methods (first and second conversion methods) based on the luminance level of input image data. The level detection circuit continuously monitors luminance levels, and the image data conversion circuit adapts its behavior in real-time, converting high-luminance data using one method and low-luminance data using another method.
2Illumination intensity
If backlight luminance is enhanced to improve display brightness, then white luminance increases, but power consumption increases
Solution Approach 1:
The patent changes the operational parameters of the liquid crystal display by switching between different data conversion methods based on luminance levels. By optimizing the relationship between input data levels and conversion methods, the system achieves improved white luminance while maintaining efficient power consumption characteristics.
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 enables a substantial improvement in white luminance with reduced power consumption by uniformly converting pixel data levels and selectively applying chromatic changes only to white peak data areas, thereby enhancing transmittance and minimizing power usage.
Implementation Method 1
An LCD is a display device utilizing the light transmittance of liquid crystals. An LCD itself does not emit light; gray scale display is accomplished by controlling the light of a backlight on the back surface of the LCD between transmission, shut-off, and an intermediate state therebetween.
Data Source
AI summary
A liquid crystal display device includes a four-color conversion circuit with no chromatic changes in which the chromaticity and luminance of input image data are maintained, a four-color conversion circuit with chromatic changes in which the chromaticity and luminance of input image data are not necessarily maintained, and a selector for switching between the outputs from the two conversion circuits according to a level detection signal from a level detection circuit that detects whether the level of input image data is equal to 100% white level or higher. Display data from the selector is supplied to a liquid crystal section that displays an image by four-color pixels of red, green, blue, and white. The image data conversion circuit controls the light emission quantity of a backlight (BL) as white color, and converts input image data so that the level of data displayed on the liquid crystal section becomes uniform.