Optical Construction with Enclosed Gap for Under-Display Fingerprint Sensing
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Solution Overview
Problem
Under-the-display fingerprint sensors in electronic devices face accuracy issues due to interference patterns like Newton's Rings, which occur when the lightguide and transmissive reflector contact each other, making it difficult to distinguish fingerprints from these patterns, thereby reducing the efficiency and accuracy of fingerprint sensing.
Innovation Solution
Incorporating an enclosed gap between the lightguide and the transmissive reflector prevents contact and thus eliminates the generation of Newton's Rings, ensuring accurate fingerprint sensing by allowing light to pass through without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lightguide and transmissive reflector are placed in close proximity to enable efficient light transmission for fingerprint sensing, then the fingerprint sensing capability is improved, but Newton's Rings interference patterns are generated due to contact between the two components, deteriorating the measurement precision
Solution Approach 1:
The patent introduces a spacer component as an intermediary element positioned between the lightguide and the transmissive reflector. This spacer maintains a precise gap that prevents direct contact between the two optical components, thereby eliminating Newton's Rings interference patterns while still allowing efficient light transmission for fingerprint sensing. The spacer acts as a mediator that resolves the contradiction by enabling close proximity without actual contact.
2Measurement precision
If the lightguide and transmissive reflector are separated to eliminate Newton's Rings interference, then the measurement precision is improved, but the light transmission efficiency is reduced due to increased distance
Solution Approach 1:
The patent optimizes the gap distance parameter between the lightguide and transmissive reflector to a specific range that balances two competing requirements: it is large enough to eliminate Newton's Rings interference (improving measurement precision) but small enough to maintain efficient light transmission (minimizing energy loss). This precise parameter control resolves the contradiction by finding the optimal separation distance.
3Productivity
If the optical components are arranged to maximize fingerprint sensing area, then the productivity of biometric authentication is improved, but the structural complexity increases due to the need for precise alignment and spacing mechanisms
Solution Approach 1:
The patent integrates the spacer component into the existing optical construction in a way that combines multiple functions: it maintains the necessary gap to prevent interference, supports the transmissive reflector in precise alignment with the lightguide, and enables large-area fingerprint sensing. By merging these functions into a single integrated component rather than separate elements, the patent reduces overall structural complexity while maintaining high productivity.
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 optical construction ensures accurate fingerprint sensing by avoiding contact between the lightguide and transmissive reflector, thereby preventing interference patterns and enhancing the efficiency of biometric authentication in electronic devices.
Implementation Method 1
The transmissive reflector substantially reflects light in a first wavelength range and substantially transmits light in a second wavelength range
Implementation Method 2
The transmissive reflector substantially reflects light in a first wavelength range and substantially transmits light in a second wavelength range
Implementation Method 3
Under-the-display fingerprint sensors in electronic devices face accuracy issues due to interference patterns like Newton's Rings, which occur when the lightguide and transmissive reflector contact each other
Data Source
AI summary
An optical construction (100) includes a lightguide (102), a transmissive reflector (112), and an optical sensor (114). The lightguide (102) includes a first major surface (104) and a second major surface (106) opposite to the first major surface (104). The first major surface (104) includes a first portion (108) and an adjoining second portion (110). The transmissive reflector (112) is disposed adjacent to the first major surface (104) of the lightguide (102). The optical sensor (114) is disposed adjacent to the transmissive reflector (112) opposite to the lightguide (102). The optical sensor (114) is aligned with the first portion (108) of the first major surface (104) of the lightguide (102), such that the optical sensor (114) receives at least a portion of light passing through the first portion (108) of the first major surface (104) and transmitted by the transmissive reflector (112). The optical construction (100) further includes an enclosed gap (116) disposed between the first portion (108) of the first major surface (104) of the lightguide (102) and the transmissive reflector (112).