Electric Shaver Comb Elements for Flat Hair Cutting
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Solution Overview
Problem
Existing shaving units for electric shavers are ineffective in cutting hairs that lie flat against the skin, particularly on flexible skin areas, and can cause skin irritation due to mechanical instability and design flaws.
Innovation Solution
The shaving unit features two inwardly directed comb elements with teeth arranged at an angle and offset, providing a narrow cutting area close to the skin, reducing skin irritation, and incorporating a recessed area to prevent skin contact, ensuring optimal hair lifting and cutting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a center trimmer with projecting teeth is used to cut hairs, then cutting effectiveness is improved, but hairs lying flat against the skin escape from the feeding area and are not cut properly
Solution Approach 1:
The patent introduces a vertical dimension by elevating the tips of the comb teeth above the plane of the comb elements. This dimensional change allows the teeth to reach and lift hairs that lie flat against the skin, solving the problem of hairs escaping the feeding area while maintaining effective cutting.
Solution Approach 2:
The elevated comb teeth perform a preliminary action by lifting and positioning hairs vertically before they reach the cutting area. This preliminary lifting action ensures that even flat-lying hairs are properly fed into the cutting zone between the foils, improving overall cutting effectiveness.
2Manufacturing precision
If the outer cutter is made thin to provide a close shave, then cutting precision is improved, but mechanical stability deteriorates
Solution Approach 1:
The outer cutter is segmented into multiple thin comb elements with teeth, rather than a single solid structure. This segmentation allows each comb element to be extremely thin for close shaving while the collective arrangement of multiple elements provides the necessary mechanical stability through distributed support.
Solution Approach 2:
The patent employs extremely thin comb elements that function as flexible yet stable structures. These thin film-like components maintain mechanical stability through their geometry and arrangement while enabling the outer cutter to be positioned extremely close to the skin for precise cutting.
3Ease of operation
If comb elements are made extremely thin to lift flat-lying hairs, then hair lifting capability is improved, but risk of skin irritation increases
Solution Approach 1:
The patent optimizes the parameters of the comb elements, specifically the distance between facing teeth tips (0.7 to 1.6 mm) and the elevation of tooth tips (up to 250 μm). These parameter changes enable effective lifting of flat-lying hairs while maintaining safe distances that prevent skin irritation and contact with the inner cutter.
Solution Approach 2:
The elevated comb teeth act as intermediaries that lift hairs away from the skin surface before cutting. This intermediary action prevents direct contact between the skin and the inner cutter, reducing the risk of skin irritation while still achieving effective hair removal.
4Productivity
If teeth are arranged offset by half pitch to improve hair feeding, then cutting performance is improved, but device complexity increases
Solution Approach 1:
The patent introduces asymmetry by offsetting the teeth of the first comb element by half the pitch relative to the second comb element. This asymmetric arrangement creates a staggered pattern that improves hair feeding efficiency by providing longer free distance in front of the tips, while the regular half-pitch offset keeps the manufacturing complexity manageable.
Data Source
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AI summary
The invention relates to a shaving unit (1) for an electric shaver which comprises an outer cutter (5) and an inner cutter (13) associated to that outer cutter. The outer and inner cutters are mounted so as to be movable relative to each other and adapted to be set in a relative motion by a drive mechanism. The inner cutter (13) provides a plurality of cutting edges (23) and abuts with its outer face on the inner face of the outer cutter (5), and the outer cutter provides a plurality of teeth (6) equipped with cutting edges (22). According to the invention, the outer cutter (5) provides two comb elements (2, 3) which are disposed opposite one another and which extend according to the direction of the relative motion. The two comb elements are aligned with respect to one another such that the tips (10) of the teeth of the first comb element (2) are facing the tips of the teeth of the second comb element (3), with the tips of the teeth being essentially spaced from one another.