Under-screen Fingerprint LCD Module with Reflective Layer

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Solution Overview

Problem

The challenge is to implement under-screen fingerprint identification on LCD screens in smart terminals, which require large battery capacities, ultra-thin bodies, and large display screens, while maintaining cost-effectiveness and avoiding excessive thickness, as OLED screens are costly and LCD screens dominate the market.

Innovation Solution

A display screen module with a backlight module, an LCD screen, a light-transmissible cover plate, a first light source integrated within the backlight module, a reflective component between the backlight module and the cover plate, and a light receiving module to face the reflective component, allowing for fingerprint identification without additional space or thickness increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If OLED screen is used to achieve under-screen fingerprint identification, then fingerprint identification function is realized, but manufacturing cost increases significantly

Engineering Contradiction:
Improvefingerprint identification functionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive OLED screens with standard LCD screens that have shorter operational lifetimes but are significantly cheaper and more widely available, enabling cost-effective under-screen fingerprint identification without requiring specialized display technology

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent modifies the optical parameters of the LCD screen by introducing a reflective layer with specific reflectivity characteristics and adjusting the light source wavelength to match the fingerprint sensor's detection range, enabling fingerprint identification functionality on conventional LCD displays

Inventive Principle:
Principle #35Parameter changes

2Reliability

If additional components are added for under-screen fingerprint identification, then fingerprint identification function is achieved, but display module thickness increases

Engineering Contradiction:
Improvefingerprint identification functionVSAvoiddisplay module thickness
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The patent combines the fingerprint identification components (light source, reflective layer, sensor) with the existing display module structure, integrating them into the same space without requiring separate dedicated layers, thereby achieving ultra-thin profile while maintaining functionality

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent nests the fingerprint identification system within the display module by placing the reflective layer between the LCD screen and backlight module, and positioning the light source and sensor within the existing structural boundaries, creating a compact nested configuration

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If additional components are added for under-screen fingerprint identification, then fingerprint identification function is achieved, but device structure becomes more complex

Engineering Contradiction:
Improvefingerprint identification functionVSAvoiddisplay module structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs the display module components to serve multiple functions: the backlight module serves both display illumination and fingerprint identification lighting, the reflective layer serves both light reflection for display and light routing for fingerprint sensing, reducing overall system complexity

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

Solution Approach 2:

The patent enables components to perform their own additional functions without requiring separate dedicated components - the existing LCD screen structure serves the fingerprint identification function through the added reflective layer, eliminating the need for complex separate fingerprint sensor modules

Inventive Principle:
Principle #25Self-service

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

Enables under-screen fingerprint identification on LCD screens without increasing the thickness of the display module, meeting user requirements for large battery capacities, ultra-thin bodies, and large display screens, while maintaining cost-effectiveness.

Implementation Method 1

a first light source arranged in a backlight source of the backlight module and independent from the backlight source, and configured to emit a first light

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Implementation Method 2

a reflective component arranged between the backlight module and the cover plate... configured to reflect the first light to form a second light

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

a light receiving module arranged to face the reflective component and configured to receive light reflected by the reflective component

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP3933671B1Display screen module and terminal
Publication Date: 2024.04.03 ZTE CORP
  • EP3933671B1 patent drawingFigure 1~1A
  • EP3933671B1 patent drawingFigure 1B~1C
  • EP3933671B1 patent drawingFigure 1D~1E

AI summary

A display screen module and a terminal. The display screen module comprises: a backlight module, an LCD screen arranged above the backlight module, a light-transmissible cover plate arranged above the LCD screen, a first light source arranged in a backlight light source of the backlight module, a reflective component arranged between the LCD screen and the cover plate, and a light-receiving module for receiving light reflected by the reflective component so as to carry out fingerprint recognition.