Helical Slot Sync Hinge for Compact Foldable Screens

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Solution Overview

Problem

Conventional foldable screens face challenges with large rotating shaft mechanisms that hinder miniaturization and synchronous rotation of left and right screens, compromising the compact design and user experience of foldable electronic devices.

Innovation Solution

A synchronous rotation mechanism utilizing sliding members with helical slots and torque swing arms, connected by slide slots and pin shafts, to achieve compact size and synchronous rotation of foldable screens.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a conventional rotating shaft mechanism is used to enable foldable screen rotation, then the rotation function is achieved, but the mechanism occupies large space which hinders device miniaturization

Engineering Contradiction:
Improvespace occupied by rotation mechanismVSAvoidsynchronous rotation of screens
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent combines the rotation control of left and right screens into a single integrated mechanism. The first and second torque swing arms are connected through a sliding member with helical slots, forming a unified structure that controls both screens simultaneously. This merging eliminates the need for separate rotation mechanisms for each screen, reducing overall space occupation while ensuring synchronous rotation through the coupled mechanical linkage.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces helical slots that convert rotational motion into linear sliding motion in a perpendicular dimension. When the torque swing arms rotate, the sliders move along the helical slots, causing the sliding member to translate in a direction perpendicular to the rotation axis. This dimensional transformation allows the mechanism to achieve synchronous rotation control while occupying less space in the rotation plane.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If the rotating shaft mechanism is miniaturized to reduce device size, then device miniaturization is achieved, but ensuring synchronous rotation of left and right screens becomes difficult

Engineering Contradiction:
Improvesize of foldable electronic deviceVSAvoidsynchronous rotation control
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The patent creates a mechanically coupled system where the left and right torque swing arms are linked through the sliding member with helical slots. This coupling ensures that both arms experience equivalent mechanical constraints and move through corresponding angles simultaneously. The helical slot geometry is designed to maintain equipotential motion relationships, ensuring that rotation of one arm automatically produces synchronized rotation of the other arm, simplifying operation despite miniaturization.

Inventive Principle:
Principle #12Equipotentiality

3Area of stationary object

If a compact rotation mechanism is designed, then space consumption is reduced, but the complexity of ensuring synchronized rotation increases

Engineering Contradiction:
Improvearea occupied by rotation mechanismVSAvoidmechanism structure complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The sliding member with helical slots serves multiple functions simultaneously: it acts as a connector between the two torque swing arms, a motion transformer converting rotation to linear displacement, and a synchronization controller ensuring both screens rotate equally. This multi-functionality reduces the need for additional separate components, maintaining structural simplicity while achieving compact dimensions and reliable synchronous operation.

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

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

The mechanism reduces the occupied space and rotation loss, enabling miniaturization and enhancing user experience by facilitating compact design and improved hardware performance.

Implementation Method 1

a first helical slot and a second helical slot are respectively provided on two sides of the sliding member; and a first torque swing arm and a second torque swing arm, respectively located at the two sides of the sliding member. The first torque swing arm and the second torque swing arm are rotatably connected to the sliding member separately. The first torque swing arm is provided with a first slider, and the first slider is accommodated in the first helical slot, so that the first slider slides along the first helical slot when the first torque swing arm rotates

Methodology Applied
Scientific EffectHelical slot mechanism: Helix

Implementation Method 2

The second torque swing arm is provided with a second slider, and the second slider is accommodated in the second helical slot, so that the second slider slides along the second helical slot when the second torque swing arm rotates, to synchronously drive the sliding member to slide in a direction perpendicular to rotation of the second torque swing arm

Methodology Applied
Scientific EffectHelical slot mechanism: Helix

Data Source

PatentEP4401390B1Synchronous rotation mechanism and foldable electronic device
Publication Date: 2026.04.15 HONOR DEVICE CO LTD
  • EP4401390B1 patent drawingFigure 1
  • EP4401390B1 patent drawingFigure 2
  • EP4401390B1 patent drawingFigure 3~4

AI summary

This application discloses a synchronous rotation mechanism and a foldable electronic device, and relates to the field of electronic device technologies. The synchronous rotation mechanism is used in a foldable electronic device. The synchronous rotation mechanism includes torque swing arms and a sliding member. The torque swing arms on two sides of the sliding member are connected by the sliding member. The torque swing arms are rotatably connected to the sliding member by sliders and helical slots, so that when the torque swing arm on one side rotates, the slider and the helical slot synchronously drive the sliding member to slide in a direction perpendicular to rotation of the torque swing arm, and then to drive the torque swing arm on another side to rotate synchronously. The synchronous rotation mechanism has a small size, and application of the synchronous rotation mechanism in a foldable electronic device can reduce a size of the foldable electronic device. This facilitates miniaturization of a main body of the foldable electronic device, to improve carry and use experience of a user.