Hair Cutting Kit Comb Geometry to Reduce Skin Bulging
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Solution Overview
Problem
Conventional hair cutting kits designed for facial skin can cause skin injury when used on thinner and more flexible areas like the armpit or intimate areas due to skin bulging between comb teeth, increasing the risk of cutting the skin.
Innovation Solution
A hair cutting kit with a comb that has a skin surface with a greater radius of curvature than the feeding surface, and a transition surface with a smaller radius, designed to reduce skin bulging and enhance cutting efficacy by guiding hairs efficiently towards the cutting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a comb with spherical or radious comb tooth tips is used, then the skin feel is improved and the comb can be used on facial skin, but the skin bulges up between the comb teeth increasing the risk of skin injury when used on thinner body areas
Solution Approach 1:
The comb tooth is designed with different surface geometries at different locations: the distal end has a first surface with a first radius of curvature for skin contact, while the proximal end has a second surface with a second radius of curvature for hair engagement. This local differentiation allows the comb to provide both comfortable skin contact and effective hair guidance without causing skin bulging that leads to injury.
Solution Approach 2:
The comb tooth surfaces are designed with specific radii of curvature - the first surface at the distal end has a larger radius of curvature than the second surface at the proximal end. This curvature gradient prevents skin bulging while maintaining skin contact comfort, and the smaller curvature at the proximal end ensures effective hair engagement and guidance toward the cutting unit.
2Productivity
If a comb designed for facial skin is used on thinner body areas, then the cutting unit can remove hair effectively, but the skin is at increased risk of being cut by the blade
Solution Approach 1:
The comb tooth geometry is optimized with the first surface having a larger radius of curvature for skin contact and the second surface having a smaller radius for hair engagement. This local differentiation ensures that when the comb is used on thinner body areas, the skin surface remains stable without bulging, while hairs are effectively engaged and guided to the cutting unit for efficient removal.
3Ease of operation
If the comb tooth geometry creates a funnel effect pushing skin together, then the comb can engage with skin, but the bulged skin enters the cutting system increasing injury risk
Solution Approach 1:
The comb tooth is designed with a gradient of radii of curvature along its length - the distal end has a larger radius for comfortable skin contact without creating a funnel effect, while the proximal end has a smaller radius for effective hair engagement. This curvature gradient eliminates the skin bulging that would otherwise enter the cutting system and cause injury.
Data Source
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AI summary
A hair cutting kit (10) comprises a cutting unit (30) and a comb (60). The comb (60) comprises a row of comb teeth (70). Some or all of the comb teeth (70) comprise, on an outer face, a skin surface (71) configured to glide on a user's skin, a feeding surface (72) configured to feed hairs towards the cutting unit, and a transition surface (73) between the skin surface and the feeding surface. The skin surface has a first surface contour line (81) having a first radius of curvature (RS), the feeding surface has a second surface contour line (82) having a second radius of curvature (RF), and the first radius of curvature is greater than the second radius of curvature.