Hair-Cutting Guard Plate With Raised Apertures for Skin Contact
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Solution Overview
Problem
Existing hair cutting appliances struggle to combine the close-cutting performance of trimmers with the superior cutting ability of foil-shavers due to the domed shape of foil-shavers interfering with the continuous skin contact required by trimmers.
Innovation Solution
A guard plate with a raised section having a curved shape and apertures, allowing for continuous skin contact while reducing pressure at transitions, and a pressure relenting zone to facilitate hair capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a domed shape is used for the guard plate to improve foil-shaver cutting performance, then hair capture ability is improved, but continuous skin contact is disrupted reducing trimmer performance
Solution Approach 1:
The guard plate incorporates different surface geometries in different regions: a domed raised section with apertures for hair capture, and a pressure relenting zone with reduced curvature for maintaining skin contact. This local differentiation allows each region to optimize its specific function while working together as a unified structure.
Solution Approach 2:
The guard plate is segmented into distinct functional zones: a raised section for foil-shaver action, a pressure relenting zone for skin contact, and a transition zone connecting them. This segmentation allows independent optimization of each zone's geometry to resolve the contradiction between domed shape benefits and skin contact requirements.
2Manufacturing precision
If the guard plate thickness is reduced to less than 120 microns at the trimming teeth for close-cutting performance, then cutting closeness is improved, but structural strength is reduced
Solution Approach 1:
The guard plate employs variable thickness distribution, being thinnest (less than 120 microns) at the trimming teeth region for close-cutting performance, while being thicker in other regions to provide overall structural strength and rigidity. This local thickness optimization resolves the contradiction between cutting precision and structural integrity.
3Object-affected harmful factors
If a transition zone is created to reduce skin pressure, then skin comfort is improved, but the surface complexity increases
Solution Approach 1:
The pressure relenting zone is designed as a predetermined geometric feature with specific curvature characteristics that proactively reduce skin pressure before the user encounters high-pressure areas. This preliminary pressure reduction is built into the static geometry rather than requiring dynamic adjustment mechanisms.
Solution Approach 2:
The pressure relenting zone utilizes controlled curvature variations, with a radius of curvature between 3mm and 7mm, to distribute skin pressure more evenly. This geometric curvature approach achieves pressure reduction through shape design rather than complex mechanical systems.
Data Source
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AI summary
According to an aspect, there is provided a guard plate (10) for a blade set (100) for a hair cutting appliance, the guard plate comprising a skin-facing side (12) and an opposing blade-facing side; a plurality of close-cutting trimming teeth (16) distributed in a longitudinal direction along an edge (18) of the guard plate, each tooth extending from the edge of the guard plate to a respective tip (20), the close-cutting trimming teeth having a thickness of less than (120) microns; a raised section (22) comprising a curved shape in a plane perpendicular to the longitudinal direction such that it is raised from the teeth towards the skin-facing side of the guard plate, wherein the curved shape of the raised section does not extend beyond a (30)-degree envelope defined by a line passing through the edge of the guard plate and offset from a tangent at the edge of the guard plate by (30) degrees; a pressure relenting zone (30) between the teeth and the raised section defining a continuous surface, wherein there is a transition (32) between the pressure relenting zone and the raised section such that, when the guard plate is passed over a user's taut skin, the skin does not directly follow the contours of the transition thereby locally reducing pressure from the skin; wherein a plurality of apertures (48) are distributed on the raised section at least within a pressure restoring zone (36) of the raised section, the pressure restoring zone being defined between a rising point and a tangent point, wherein the rising point is where a perpendicular distance from the skin-facing surface of the guard plate to a pressure relenting line peaks, wherein the pressure relenting line is defined by a tangent of the raised section in a plane perpendicular to the longitudinal direction, the tangent passing through the edge of the guard plate, and wherein the tangent point is on the raised section at the tangent of the pressure relenting line.