Display-Based Fingerprint Reader Using Light Guide

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Solution Overview

Problem

Conventional fingerprint scanners occupy valuable space on electronic devices, such as mobile phones, and traditional authentication methods like PIN codes and passwords are vulnerable to unauthorized access.

Innovation Solution

An electronic device with a display assembly that incorporates fingerprint detection functionality, using light-emitting pixels, a light guide, and sensors to illuminate and reflect light from a user's finger, allowing for fingerprint authentication without the need for a separate scanner, optimizing space and enhancing security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate fingerprint scanner is incorporated into the electronic device, then fingerprint authentication capability is improved, but the available display area is reduced

Engineering Contradiction:
Improveauthentication capabilityVSAvoiddisplay area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the fingerprint scanner with the display assembly by integrating light sensors and a light guide directly into the display structure. The light guide is positioned between the display and touch-sensitive input, allowing the display to serve dual purposes: visual output and fingerprint illumination/detection, thereby eliminating the need for a separate fingerprint scanner component

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The display assembly is designed to perform multiple functions: it serves as both the visual display interface and the fingerprint authentication interface. The same display structure houses both the light-emitting pixels for illumination and the light sensors for detecting reflected light from the fingerprint, making the display a multi-functional component

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If conventional authentication methods like PIN codes or passwords are used, then ease of operation is improved, but security against unauthorized access deteriorates

Engineering Contradiction:
Improveauthentication convenienceVSAvoidsecurity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces mechanical or manual authentication systems (keyboard input, touch screen typing of PINs or passwords) with an optical biometric authentication system. Instead of requiring users to manually enter authentication information, the system uses light-based fingerprint detection to automatically verify user identity, combining ease of use with enhanced security

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables efficient fingerprint authentication within the device's display, reducing space usage and improving security by using the display to both illuminate and detect fingerprints, providing a unique pattern for user authentication.

Implementation Method 1

the reflected light propagates in the light guide by internal reflection

Methodology Applied
Scientific EffectInternal reflection: Reflection

Data Source

PatentEP3474187B1Electronic device with display-based fingerprint reader
Publication Date: 2021.01.06 SONY GROUP CORP
  • EP3474187B1 patent drawingFigure 1~2
  • EP3474187B1 patent drawingFigure 3~4

AI summary

A display and finger print reader assembly for an electronic device that includes fingerprint detection functionality. A portion of the display assembly is used to "light up" the finger and reflections from the finger are detected and used to identify and/or authenticate the user. The display and finger print reader assembly for an electronic device includes a display having an arrangement of light emitting pixels, a light guide juxtaposed the arrangement of pixels of the display, and light sensors. Light emitted from the pixels illuminates the user's finger that is placed against the display and finger print reader assembly. The emitted light that is reflected by the user's finger propagates in the light guide to one or more of the light sensors and indicates a fingerprint characteristic of a portion of the user's finger adjacent the pixel or pixels from which the light is emitted.