Cholesteric Color Filter with Auxiliary Layer for LCD Light Efficiency
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Solution Overview
Problem
LCD devices suffer from low light efficiency due to the low light transmittance of color filters, which absorb most wavelength bands except for a transmission wavelength band, resulting in only one-third of white light being usable for image display.
Innovation Solution
The implementation of a cholesteric color filter layer with an auxiliary color filter layer that transmits a fixed wavelength band in the front viewing direction while filtering all other wavelength bands in the side viewing direction, combined with a backlight unit and polarizing films to enhance light transmittance and prevent color shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional color filter is used, then the LCD device can display colors, but the light transmittance is low because the color filter absorbs most wavelength bands except for a transmission wavelength band
Solution Approach 1:
The patent changes the optical parameters of the color filter by introducing a cholesteric liquid crystal layer with specific helical structure that reflects specific wavelength bands based on its pitch, replacing the conventional absorption-based color filtering mechanism with a reflection-based mechanism that preserves more light
Solution Approach 2:
The patent creates a composite color filter structure combining cholesteric liquid crystal layer, auxiliary color filter layer, and reflective plate to achieve both color separation and high light efficiency through the synergistic effect of reflection and selective absorption
2Illumination intensity
If a cholesteric color filter layer is used to enhance light transmittance, then more light can be utilized for display, but color shift occurs at side viewing directions
Solution Approach 1:
The patent segments the color filtering function into two parts: the cholesteric liquid crystal layer handles front-viewing color selection through reflection, while the auxiliary color filter layer handles side-viewing color correction through selective absorption of reflected light
Solution Approach 2:
The auxiliary color filter layer acts as an intermediary between the cholesteric liquid crystal layer and the viewer, correcting the color shift caused by the cholesteric layer's viewing angle dependence by absorbing specific wavelength bands that cause color distortion
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
This configuration significantly enhances light transmittance and prevents color shift at various viewing angles, thereby improving the color reproductive ratio and overall light efficiency of LCD devices.
Implementation Method 1
a cholesteric color filter layer disposed on the first substrate
Implementation Method 2
transmit a fixed wavelength band of light progressing in a front viewing direction of the cholesteric color filter layer
Implementation Method 3
filter every wavelength band of light progressing in a side viewing direction of the cholesteric color filter layer except the fixed wavelength band of light
Data Source
AI summary
An LCD device is disclosed which includes: a first substrate; a second substrate disposed to face the first substrate; a liquid crystal layer inserted between the first and second substrates; a cholesteric color filter layer disposed on the first substrate; and an auxiliary color filter layer disposed on the cholesteric color filter layer and formed to transmit a fixed wavelength band of light progressing in a front viewing direction of the cholesteric color filter layer and filter every wavelength band of light progressing in a side viewing direction of the cholesteric color filter layer except the fixed wavelength band of light.