Under-Display Fingerprint Optics With Refractive Index Layering

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Solution Overview

Problem

Existing display devices face challenges in achieving improved light transmittance and fingerprint recognition performance, particularly when integrating a fingerprint sensor on a display panel.

Innovation Solution

The display device incorporates a fingerprint sensor layer with an optical pattern layer that includes light blocking and transmitting portions, and refractive index layers to enhance light transmission and fingerprint recognition, utilizing materials like silicon nitride and transparent organic materials to refract light towards light receiving elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fingerprint sensor is integrated on a display panel, then fingerprint recognition functionality is added, but light transmittance and recognition performance deteriorate

Engineering Contradiction:

Improvefingerprint recognition functionalityVSAvoidfingerprint recognition performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an optical pattern layer as an intermediary component between the fingerprint sensor layer and the display panel. This layer includes light blocking portions and light transmitting portions that act as mediators to guide reflected light from the fingerprint sensor through the display panel to the light receiving elements, thereby improving recognition performance while maintaining the integrated structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies optical parameters by introducing layers with specific refractive indices. The first light transmitting layer has a first refractive index and the second light transmitting layer has a second refractive index different from the first, optimizing light transmission characteristics to enhance fingerprint recognition performance through the display panel

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If light blocking portions are added to the optical pattern layer, then light direction control is improved, but light transmittance deteriorates

Engineering Contradiction:

Improvelight direction controlVSAvoidlight transmittance

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The optical pattern layer implements local quality by having different regions with different optical properties. The light blocking portions are strategically positioned to control light direction in specific areas, while the light transmitting portions allow light passage in other areas. This localized differentiation enables precise light direction control without uniformly reducing light transmittance across the entire layer

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If multiple light transmitting layers with different refractive indices are added, then light transmission is optimized, but device complexity increases

Engineering Contradiction:

Improvelight transmissionVSAvoidlayer structure complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent segments the light transmitting structure into multiple distinct layers, each with specific refractive index characteristics. The first light transmitting layer and second light transmitting layer are separated into independent structural units, allowing each layer to be optimized for specific optical functions while maintaining overall system organization and manufacturability

Inventive Principle:

Principle #1Segmentation

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 improves light transmittance and enhances fingerprint recognition performance by optimizing light reception efficiency and maintaining cut-off angles, thereby improving overall sensor functionality.

Implementation Method 1

a first light transmitting layer with a first refractive index and that is disposed on the light blocking portion; a second light transmitting layer with a second refractive index that differs from the first refractive index and that is disposed on the first light transmitting layer

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

an optical pattern layer disposed on the substrate and that includes a light blocking portion and a light transmitting portion that passes through the light blocking portion in one direction

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 3

a fingerprint sensor layer that receives light reflected by an external object

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS12481387B2Display device and manufacturing method thereof

Publication Date: 2025.11.25 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a fingerprint sensor layer that receives light reflected by an external object; a substrate disposed on the fingerprint sensor layer; an optical pattern layer disposed on the substrate and that includes a light blocking portion and a light transmitting portion that passes through the light blocking portion in one direction; a first light transmitting layer with a first refractive index and that is disposed on the light blocking portion; a second light transmitting layer with a second refractive index different from the first refractive index and that is disposed on the first light transmitting layer; and a light emitting element layer disposed on the second light transmitting layer.