Foldable Housing Structure for Flexible Circuit Bend Control

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Solution Overview

Problem

Foldable electronic devices experience fracture failures in the flexible circuit board due to large local stresses during folding and unfolding, reducing their service life.

Innovation Solution

The design incorporates arc-shaped surfaces on the housings to guide the bending part of the flexible circuit board into a preset shape, controlling the bending radius and alleviating local stress, using compressing members to facilitate this process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the flexible circuit board is allowed to bend freely during folding and unfolding, then the device can achieve compact folding and easy storage, but the bending part experiences large local stress leading to fracture failure

Engineering Contradiction:
Improvefolding and unfoldingVSAvoidservice life
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces arc-shaped guiding surfaces on the housing that constrain the bending part of the flexible circuit board to follow a predetermined curved path during folding and unfolding. This controlled curvature prevents sharp bends and reduces local stress concentration, thereby extending the service life while maintaining folding functionality

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Ease of operation

If the bending part of the flexible circuit board is given sufficient redundant length to meet bending needs, then the device can achieve smooth folding motion, but the bending part becomes more susceptible to fracture due to increased stress cycles

Engineering Contradiction:
Improvebending motionVSAvoidfracture resistance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent pre-defines the bending trajectory through arc-shaped guiding surfaces, so that the bending part follows a predetermined safe path during folding and unfolding. This preliminary constraint on the bending path prevents unpredictable stress distributions and reduces the risk of fracture while ensuring smooth motion

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4510786B1Foldable electronic device
Publication Date: 2026.04.22 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4510786B1 patent drawingFigure 1~2
  • EP4510786B1 patent drawingFigure 3~4
  • EP4510786B1 patent drawingFigure 5~6

AI summary

A foldable electronic device (100) includes a rotation shaft (1), a housing assembly (2) and a flexible circuit board (3). The housing assembly (2) includes a first housing (21) and a second housing (22), and the first housing (21) and the second housing (22) are rotatably connected to both sides of the rotation shaft (1), respectively. The first housing (21) has a first arc-shaped surface (212), and in a process of switching from a folded state to a flattened state, the first arc-shaped surface (212) abuts against the bending part (32), to guide the bending part (32) to bend into a preset shape; and/or the second housing (22) has a second arc-shaped surface (222), and in a process of switching from a folded state to a flattened state, the second arc-shaped surface abuts against the bending part, to guide the bending part to bend into a preset shape.