String set, warp string, and weft string

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Solution Overview

Problem

Existing badminton racket string sets struggle to simultaneously improve hairpin performance (spinning performance) and cut smash performance, as these shots require different string functions.

Innovation Solution

A string set configuration where the main string has a larger surface friction force and diameter, and the cross string has a smaller surface friction force and diameter, allowing for enhanced spin application during hairpin shots and improved mobility during cut smash shots.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a string with large surface friction force and large diameter is used, then hairpin performance is improved, but cut smash performance deteriorates

Engineering Contradiction:
Improvehairpin performanceVSAvoidcut smash performance
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies different string properties to different positions on the racket. The main string (horizontal) has large diameter and large surface friction force to improve hairpin performance, while the cross string (vertical) has small diameter and small surface friction force to improve cut smash performance. This local differentiation of string characteristics resolves the contradiction between the two shot types.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The string set is segmented into two distinct components with different properties: the main string and the cross string. Each segment serves a specific function - the main string optimized for spin generation during hairpin shots, and the cross string optimized for mobility during cut smash shots. This segmentation allows simultaneous optimization of both performance aspects.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If a string with small surface friction force and small diameter is used, then cut smash performance is improved, but hairpin performance deteriorates

Engineering Contradiction:
Improvecut smash performanceVSAvoidhairpin performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The cross string is specifically designed with small diameter and small surface friction force to facilitate mobility and improve cut smash performance, while the main string compensates for spin generation capability with its large diameter and large surface friction force. This local quality assignment resolves the contradiction.

Inventive Principle:
Principle #3Local quality

3Strength

If the main string has large diameter, then edge breakage resistance is improved, but shuttlecock repulsion feeling deteriorates

Engineering Contradiction:
Improveedge breakage resistanceVSAvoidshuttlecock repulsion feeling
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The main string is assigned large diameter to improve edge breakage resistance at the racket edges, while the cross string has small diameter to maintain good shuttlecock repulsion feeling. This local differentiation of string diameters resolves the contradiction between durability and playing feel.

Inventive Principle:
Principle #3Local quality

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

This configuration enables simultaneous improvement of hairpin and cut smash performances by optimizing string friction and diameter distribution, while also compensating for potential drawbacks such as reduced shuttlecock repulsion and increased edge breakage risk.

Implementation Method 1

The second string has a larger surface friction force and a larger diameter than the surface friction force and the diameter of the first string

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The first string has a small surface friction force and a small diameter

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3449983B1String set, warp string, and weft string
Publication Date: 2025.05.28 YONEX CO LTD
  • EP3449983B1 patent drawingFigure 1
  • EP3449983B1 patent drawingFigure 2A~2B
  • EP3449983B1 patent drawingFigure 3A~3B

AI summary

To provide a string set that ensures improving a hairpin performance and a cut smash performance. A string set (20) is a string set strung on a racket as a main string and a cross string, and is configured to include a first string (22) strung as any one of the main string and the cross string and has a small friction force and a small diameter and a second string (21) strung as another one of the main string and the cross string and has a larger friction force and a larger diameter than the diameter and the surface friction force of the first string. This distributes functions to the first string and the second string to obtain both the hairpin performance, which is improved by the large surface friction force and outer diameter of the string, and the cut smash performance, which is improved by the small surface friction force and outer diameter of the string, at the same time.