Optical Pattern Layer Design for In-Display Fingerprint Sensors
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Solution Overview
Problem
Display devices with integrated fingerprint sensors face challenges in achieving high optical transmittance while maintaining accurate fingerprint recognition, as existing designs often compromise between light transmission and sensor effectiveness.
Innovation Solution
A display device with a detection sensor configuration that includes a base layer, biometric sensing layer, optical pattern layer, and sensing dielectric layer, where the optical pattern layer features transmission parts and light-shield parts with recessed light-shield patterns, and the sensing dielectric layer has recessed dielectric patterns that overlap the light-shield patterns, enhancing light refraction and transmission while improving fingerprint recognition accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fingerprint sensor is integrated into the display device, then fingerprint recognition function is added, but optical transmittance decreases
Solution Approach 1:
The optical pattern layer is divided into multiple transmission parts and light-shield parts. The transmission parts allow light to pass through to the biometric sensing layer, while the light-shield parts block light to prevent interference. This segmentation enables the coexistence of display function and fingerprint sensing function in the same region.
Solution Approach 2:
Different regions of the optical pattern layer have different optical properties. The transmission parts have high optical transmittance to allow light reaching the sensing layer, while the light-shield parts have low transmittance to block stray light. This local differentiation optimizes both display quality and sensing accuracy.
2Measurement precision
If light-shield parts are added to block stray light, then sensing accuracy improves, but optical transmittance further decreases
Solution Approach 1:
The light-shield patterns are designed with curved boundaries rather than sharp edges. This curvature reduces light diffraction and scattering at the boundaries, minimizing the impact on overall optical transmittance while still effectively blocking stray light from reaching the sensing layer.
Solution Approach 2:
The optical pattern layer uses composite material design combining transparent regions and light-shielding regions in a single layer structure. This allows simultaneous optimization of light transmission for display and light blocking for sensing accuracy without requiring separate layers.
3Illumination intensity
If transmission parts are made larger to improve light transmission, then optical transmittance increases, but sensing accuracy decreases due to increased stray light
Solution Approach 1:
The light-shield parts act as intermediary elements between the transmission parts and the biometric sensing layer. They selectively block stray light that would otherwise reach the sensing layer and cause false readings, while allowing the transmission parts to maintain large areas for sufficient light transmission.
Solution Approach 2:
The solution addresses the two-dimensional trade-off between transmission area and sensing accuracy by introducing a third dimensional consideration - the vertical positioning and thickness of the light-shield parts. By optimizing the depth and shape of light-shield patterns in the vertical dimension, both large transmission areas and high sensing accuracy can be achieved.
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 configuration increases optical transmittance and sensitivity of fingerprint recognition, allowing for effective user input detection and improved display performance.
Implementation Method 1
when the light is incident through the display module, incident light on the light-shield part is refracted at the sensing dielectric layer and enters the transmission parts
Data Source
AI summary
A display device includes: a display module configured to display an image; and a detection sensor disposed on the display module, wherein the detection sensor includes a base layer, a biometric sensing layer, an optical pattern layer, and a sensing dielectric layer, wherein the biometric sensing layer is disposed on the base layer, wherein the optical pattern layer is disposed on the biometric sensing layer, and the sensing dielectric layer is disposed on the optical pattern layer. The optical pattern layer includes: a plurality of transmission parts that provide the biometric sensing layer with light that is externally incident through the display module; and a light-shield part that at least partially surrounds the plurality of transmission parts. The light-shield part includes a plurality of light-shield patterns that are recessed in a direction toward the base layer.