Trans-Reflective Nanostructured RGB Filters for LCD
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Solution Overview
Problem
Pigment/dye based color filters in LCD, CMOS, and CCD devices degrade over time and are light sensitive, limiting their lifespan and efficiency, and as devices shrink, there's a need for smaller filters that can convert between additive and subtractive color modes.
Innovation Solution
Nanostructured trans-reflective filters with film stacks comprising metal and dielectric films of specific thicknesses that transmit filtered light within certain wavelengths and reflect other wavelengths, allowing for polarization-insensitive and -sensitive filtering, and switchability between color modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pigment/dye based color filters are used to transmit desired colors, then color filtering is achieved, but light absorption causes degradation and limited lifespan
Solution Approach 1:
The patent inverts the traditional absorptive filtering mechanism by using trans-reflective filters that reflect unwanted wavelengths instead of absorbing them. The film stack structure with alternating high and low refractive index layers creates constructive and destructive interference patterns that reflect specific wavelength ranges while transmitting others, eliminating the degradation issues of pigment-based absorptive filters.
Solution Approach 2:
The patent changes the physical parameters of the filtering mechanism by using dielectric materials with specific refractive indices and controlled layer thicknesses. By adjusting the optical parameters (refractive index, layer thickness) rather than relying on chemical pigments, the system achieves wavelength-selective filtering without light absorption and associated degradation.
2Area of moving object
If filter size is reduced to accommodate smaller devices, then device miniaturization is achieved, but filtering performance may deteriorate
Solution Approach 1:
The patent applies local quality by designing film stacks with spatially varying layer thicknesses and material compositions tailored to specific wavelength ranges. Each pixel's film stack is locally optimized for its required color transmission, allowing small footprint filters to maintain high filtering performance through precise local control of optical properties rather than relying on large uniform filtering areas.
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 trans-reflective filters achieve high transmission efficiency (>70%) with reduced light loss, increased lifespan, and customizable spectral sensitivity, enabling thinner display devices and efficient color mode conversions.
Implementation Method 1
The film stack includes a first metal film disposed on a substrate having a first thickness, a first dielectric film disposed on the first metal film having a second thickness, a second metal film disposed on the first dielectric film having a third thickness, and a second dielectric film disposed on the second metal film having a fourth thickness
Data Source
AI summary
Embodiments described herein relate to nanostructured trans-reflective filters having sub-wavelength dimensions. In one embodiment, the trans-reflective filter includes a film stack that transmits a filtered light within a range of wavelengths and reflects light not within the first range of wavelengths. The film stack includes a first metal film disposed on a substrate having a first thickness, a first dielectric film disposed on the first metal film having a second thickness, a second metal film disposed on the first dielectric film having a third thickness, and a second dielectric film disposed on the second metal film having a fourth thickness.