Multilayer Partial Mirror for Display Luminance and Fingerprint Sensing
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Solution Overview
Problem
Collimating reflective polarizers in display devices reduce axial luminance by depolarizing light and increasing power consumption, leading to decreased battery life in electronic devices.
Innovation Solution
A multilayer partial mirror with alternating polymeric layers, integrated between polymeric skin layers, provides improved collimation for both s-polarized and p-polarized light, reducing on-axis reflectance and enhancing axial luminance while allowing infrared light to pass for fingerprint sensing applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If collimating reflective polarizers are used to eliminate optical artifacts, then reflective Moiré is eliminated, but axial luminance decreases
Solution Approach 1:
The patent changes the refractive index parameters of the polymeric layers to achieve wavelength-selective optical control. By carefully selecting refractive indices (nx1, ny1, nz1 for first layer and nx2, ny2, nz2 for second layer) with specific relationships (nx1-ny1<0.05, nz1<nx1-0.06, nz1<nx2-0.06), the multilayer structure achieves different reflectance characteristics for visible and infrared wavelengths, eliminating Moiré artifacts while preserving axial luminance and enabling fingerprint sensing
Solution Approach 2:
The patent uses composite multilayer polymeric structures with alternating first and second polymeric layers (at least 50 layers) having different refractive index characteristics. This composite structure, integrated between polymeric skin layers, provides superior optical control compared to single-material solutions, achieving simultaneous elimination of reflective Moiré, maintenance of axial luminance, and infrared transmission for fingerprint sensing
2Object-affected harmful factors
If collimating reflective polarizers are used to eliminate optical artifacts, then reflective Moiré is eliminated, but power consumption increases
Solution Approach 1:
The patent modifies the optical parameters of the multilayer structure to achieve passive optical control without requiring additional active components. By adjusting refractive index relationships and layer thicknesses, the system eliminates Moiré artifacts through optical design rather than electronic processing, thereby reducing power consumption while maintaining display quality
Solution Approach 2:
The multilayer polymeric structure provides self-service by passively eliminating reflective Moiré through its inherent optical properties. The alternating layers with specific refractive index relationships automatically perform the collimation and artifact elimination function without requiring external power input or active control mechanisms, thus reducing overall system power consumption
3Illumination intensity
If the multilayer partial mirror is designed with specific refractive index relationships, then axial luminance is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter relationships (nx1-ny1<0.05, nz1<nx1-0.06, nz1<nx2-0.06) that provide design guidance for manufacturing. These parameter specifications enable manufacturers to achieve the desired axial luminance enhancement while maintaining realistic manufacturing tolerances, balancing performance requirements with fabrication capabilities
Solution Approach 2:
The patent applies local quality by specifying different refractive index requirements for different layers and directions. The first and second polymeric layers have distinct refractive index characteristics tailored to their specific optical functions, allowing optimization of axial luminance while managing manufacturing complexity through localized material property control
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 multilayer partial mirror enhances axial luminance by effectively collimating off-axis light and reducing on-axis reflectance, while being suitable for infrared fingerprint sensing due to its transmissive properties for infrared wavelengths.
Implementation Method 1
The plurality of alternating first and second polymeric layers includes respective indices nx1 and nx2 along a same in-plane x-direction, respective indices ny1 and ny2 along an in-plane y-direction orthogonal to the x-direction, and respective indices nz1 and nz2 along a z-direction of the polymeric layers orthogonal to the x- and y-directions. For at least one wavelength in a visible wavelength range, nz1 is less than each of nx1 and nx2 by at least 0.06.
Implementation Method 2
For the visible wavelength range, and for each of the first and second polymeric skin layers, corresponding indices of the polymeric skin layer and one of the first polymeric layers and second polymeric layers along each of x-, y-, and z-directions are within about 0.05 of each other. For the visible wavelength range and an incident light propagating in an incident plane that includes the x-direction, and for an s-polarized incident light, the plurality of alternating first and second polymeric layers has an average reflectance Rs1 for a first incident angle of less than about 10 degrees.
Implementation Method 3
The multilayer partial mirror is suitable for infrared fingerprint sensing due to its transmissive properties for infrared wavelengths.
Data Source
AI summary
A multilayer partial mirror includes a plurality of alternating first a second polymeric layers numbering at least 50 in total, disposed between, and integrally formed with, opposing first and second polymeric skin layers. For a visible wavelength range extending from about 420 nm to about 680 nm and an incident light propagating in an incident plane that includes a x-direction, and for an s-polarized incident light, the multilayer partial mirror has an average reflectance Rs1 for a first incident angle of less than about 10 degrees, and an average reflectance Rs2 for a second incident angle of greater than about 45 degrees, and for a p-polarized incident light, the multilayer partial mirror has an average reflectance Rp1 for the first incident angle, and an average reflectance Rp2 for the second incident angle. Each of Rs2/Rs1 and Rp2/Rp1 is greater than about 1.15.