Expandable Mobile Terminal With Spring-Tensioned Flexible Display

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Solution Overview

Problem

Existing mobile terminals with expandable screens face issues of screen wrinkling and luminance deviations when using flexible display panels.

Innovation Solution

A mobile terminal design incorporating a first and second frame, a third rear portion, a roller, a flexible display panel, a driving unit, and a spring member with a spiral spring to maintain constant force, preventing screen wrinkling and luminance deviations during expansion and contraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If a flexible display panel is used to provide an expandable screen, then the screen size can be increased, but screen wrinkles and luminance deviations occur

Engineering Contradiction:
Improvescreen sizeVSAvoidscreen quality
Core Design Contradiction:
Area of moving objectVSReliability

Solution Approach 1:

The patent uses a flexible display panel that can be rolled and unrolled to expand and contract the screen. The flexible panel is wrapped around a roller to enable smooth expansion and contraction while maintaining screen integrity and preventing wrinkles through proper tension distribution.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs a spring member that provides constant force to maintain appropriate tension on the flexible display panel during expansion and contraction. This constant force ensures the panel remains taut without excessive tension that could cause wrinkles or luminance deviations.

Inventive Principle:
Principle #35Parameter changes

2Area of moving object

If the screen is expanded using a roller mechanism, then the display area is increased, but screen wrinkles occur

Engineering Contradiction:
Improvedisplay areaVSAvoidscreen flatness
Core Design Contradiction:
Area of moving objectVSShape

Solution Approach 1:

The flexible display panel is wrapped around a roller to enable smooth expansion and contraction. The roller mechanism allows the panel to maintain proper curvature during rolling while presenting a flat display surface when extended, preventing wrinkles through controlled tension distribution.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

A spring member provides constant force to maintain appropriate tension on the flexible display panel during expansion and contraction. This constant force ensures the panel remains taut without excessive tension that could cause wrinkles or luminance deviations.

Inventive Principle:
Principle #35Parameter changes

3Area of moving object

If the flexible display panel is stretched during expansion, then the screen size increases, but luminance deviations occur

Engineering Contradiction:
Improvescreen sizeVSAvoidluminance uniformity
Core Design Contradiction:
Area of moving objectVSIllumination intensity

Solution Approach 1:

The spring member provides constant force to maintain consistent tension on the flexible display panel throughout the expansion and contraction range. This consistent tension prevents over-stretching that would cause luminance deviations, ensuring uniform illumination across the display surface.

Inventive Principle:
Principle #35Parameter changes

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

Prevents users from recognizing screen wrinkles and luminance deviations, ensuring a seamless image output across the expanded screen.

Implementation Method 1

a spiral spring disposed to be wound around or unwound from the fixed shaft, wherein the spiral spring generates a constant attractive force while being wound around or unwound from the fixed shaft

Methodology Applied
Scientific EffectSpiral spring: Spring

Data Source

PatentEP4089984B1Mobile terminal
Publication Date: 2025.08.13 LG ELECTRONICS INC
  • EP4089984B1 patent drawingFigure 1
  • EP4089984B1 patent drawingFigure 2
  • EP4089984B1 patent drawingFigure 3(a)~3(b)

AI summary

Disclosed is a mobile terminal including a first frame, a second frame, a drive unit configured to move the second frame in a first direction, where the drive unit includes a driving elastic part having one end fixed to the first frame and an opposite end fixed to the second frame, the driving elastic part being configured to provide tension force, and a stopper configured to fix the driving elastic part in a compressed state. As the drive unit configured to provide driving force for extension of a frame without a motor is provided, the mounting space required for the drive unit may be reduced and the frame may be moved at a faster speed than when a motor is used. Therefore, usability may be improved.