Rotary Trigger Grip for Electric Tools to Reduce Wrist Strain

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Solution Overview

Problem

The existing electric tools require the user to press a switch in a front-rear direction, which causes strain and discomfort during extended use, particularly affecting the arm and wrist.

Innovation Solution

The electric tool incorporates a rotary trigger mechanism with first and second triggers that rotate orthogonally to the grip's extension direction, allowing operation through a more ergonomic and comfortable motion, reducing user strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a linear pressing switch is used in the front-rear direction, then the switch can be operated with a simple structure, but the user experiences arm and wrist strain during extended use

Engineering Contradiction:
Improveswitch structureVSAvoiduser comfort
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent transforms the linear pressing motion (one-dimensional front-rear movement) into a rotary motion (two-dimensional circular movement). The trigger member rotates about a rotation axis perpendicular to the grip's extension direction, allowing the user's finger to operate the switch by a natural gripping and rotating motion rather than repeated linear pressing, thereby reducing strain on the arm and wrist.

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

2Ease of operation

If the switch is positioned for easy access, then the user can operate it conveniently, but the arm and wrist become burdened during prolonged tasks

Engineering Contradiction:
Improveswitch accessibilityVSAvoidoperational duration
Core Design Contradiction:
Ease of operationVSDuration of action of moving object

Solution Approach 1:

By changing the operating motion from linear pressing to rotary movement, the patent enables more natural and less fatiguing finger motion. The rotation axis is positioned so that the trigger extends in the forward direction and rotates when pressed, creating an ergonomic interface that reduces cumulative strain during extended operational periods.

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

3Ease of operation

If a rotary trigger mechanism is implemented, then user fatigue is reduced, but the device complexity increases

Engineering Contradiction:
Improveuser comfortVSAvoidtrigger mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The trigger mechanism is segmented into distinct functional components: the trigger member itself, the rotation axis, and the connection to the switch. This modular segmentation allows for easier manufacturing, assembly, and maintenance while achieving the ergonomic rotary operation. The trigger member can be independently designed and positioned without affecting the entire switch assembly.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4650112A1Electric tool
Publication Date: 2025.11.19 MAX CO LTD
  • EP4650112A1 patent drawingFigure 1A~1B
  • EP4650112A1 patent drawingFigure 1C
  • EP4650112A1 patent drawingFigure 2(A)~2(E)

AI summary

This electric tool comprises: a motor; a drive unit operated by driving the motor; a grip; a first rotary shaft which is provided to the grip and extends in the extension direction of the grip; and a first trigger which is exposed on the front side of the grip and rotates in a direction perpendicular to or substantially perpendicular to the extension direction with respect to the first rotary shaft when a portion exposed on the front side is pressed down, wherein the motor operates on the basis of the rotation of the first trigger.