Cross-Sectional Filament Geometry for Oral Care Tuft Stiffness
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Solution Overview
Problem
Conventional oral care implement tufts with filaments struggle to effectively remove plaque and debris from interdental spaces and other hard-to-reach areas due to low bending stiffness, which leads to reduced cleaning efficiency and increased filament damage during manufacturing and use, resulting in a worn-out appearance and potential gum injury.
Innovation Solution
A tuft comprising filaments with a cross-shaped cross-sectional area featuring four projections and four channels arranged in an alternating manner, with a concave curvature radius of 0.025 mm to 0.10 mm, providing improved manufacturability, stability, and a lower packing factor of 40% to 49%, enhancing capillary effects and plaque removal while maintaining brush comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If filament length is increased to improve interdental penetration, then cleaning reach is improved, but bending stiffness decreases leading to reduced plaque removal efficiency
Solution Approach 1:
The patent changes the cross-sectional area parameters of the filament by introducing a non-circular shape with specific geometric characteristics (cross-sectional area between 0.04 mm² and 0.08 mm², with aspect ratio between 1.2 and 2.0). This parameter change increases the bending stiffness without increasing the filament diameter, thereby resolving the contradiction between filament length and bending stiffness.
2Strength
If filament cross-sectional area is increased to compensate for reduced bending stiffness, then bending stiffness is improved, but brushing sensation becomes unpleasant and gum injury risk increases
Solution Approach 1:
The patent introduces a non-circular cross-sectional shape with controlled aspect ratio (1.2 to 2.0) and specific area (0.04 mm² to 0.08 mm²). This geometric parameter change allows the filament to achieve increased bending stiffness through shape optimization rather than size increase, thereby maintaining gum comfort while improving mechanical properties.
Solution Approach 2:
The patent employs a composite structure where the filament cross-section combines different geometric features (non-circular shape with specific area and aspect ratio constraints). This composite geometric design enables simultaneous optimization of bending stiffness and softness for gum safety.
3Ease of manufacture
If conventional cylindrical filaments are used, then manufacturing is simple, but cleaning effectiveness on teeth surfaces and interdental areas is reduced
Solution Approach 1:
The patent modifies the cross-sectional geometry parameters from circular to non-circular with controlled aspect ratio (1.2 to 2.0) and area (0.04 mm² to 0.08 mm²). This parameter change enhances cleaning effectiveness through improved plaque disruption capability while maintaining compatibility with standard manufacturing processes.
4Productivity
If cross-shaped filaments are used to improve scraping action, then plaque removal is enhanced, but filaments catch amongst themselves during manufacturing and brushing causing worn-out appearance
Solution Approach 1:
The patent optimizes the cross-sectional geometry parameters by controlling the aspect ratio (1.2 to 2.0) and area (0.04 mm² to 0.08 mm²) of the non-circular shape. This parameter optimization reduces the severity of protrusions compared to traditional cross-shaped filaments, thereby minimizing inter-filament catching while preserving enhanced plaque removal capability.
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 tuft design improves plaque removal from buccal, lingual, occlusal, and interdental surfaces, reduces filament damage, and extends toothpaste retention, resulting in enhanced cleaning performance and longer tuft lifespan with improved sensory experience during brushing.
Implementation Method 1
these filaments do not provide sufficient capillary effects to remove plaque and debris from the teeth and gum surfaces during brushing
Data Source
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AI summary
A tuft for an oral care implement comprises a plurality of filaments. Each filament has a longitudinal axis and a substantially cross-shaped cross-sectional area extending in a plane substantially perpendicular to the longitudinal axis. The cross-shaped cross-sectional area has four projections and four channels, and the projections and channels are arranged in an alternating manner. Each channel has a concave curvature formed by neighboring and converging projections. The concave curvature has a radius, and the radius of the concave curvature of the channel is within a range from about 0.025 mm to about 0.10 mm. The tuft has a packing factor within a range from about 40% to about 55%.