Rotary Shaver Outer Blade with Radial Hair Inlets
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Solution Overview
Problem
Rotary electric shavers face challenges in smoothly moving along uneven skin surfaces, reliably catching different hair types, and preventing skin damage from deep shaving, as existing solutions often conflict with each other.
Innovation Solution
The rotary electric shaver features an outer blade with annular shaving surfaces and elongated hair inlets that are wider at the ends in the circumferential direction, allowing for improved hair catching performance while minimizing skin contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer blade is strongly pressed against skin to improve hair catching performance, then hair cutting effectiveness is improved, but skin damage due to deep shaving occurs
Solution Approach 1:
The hair inlets are designed with non-uniform cross-sections featuring widened portions at specific locations, creating local quality variations that enhance hair catching in certain areas while maintaining skin safety in others. This local differentiation allows the blade to effectively catch hairs of various lengths and directions without requiring strong overall pressing pressure that would damage the skin.
2Manufacturing precision
If the outer blade is made rigid to maintain shaving precision, then shaving precision is improved, but the blade cannot smoothly follow uneven skin surfaces
Solution Approach 1:
The outer blade is designed with hair inlets that have varying cross-sectional shapes along their lengths, including widened portions that allow dynamic adjustment. This dynamic structure enables the blade to adapt to uneven skin surfaces while maintaining precise shaving performance, as the non-uniform inlet shapes can flex and conform to skin contours.
3Reliability
If the hair inlets are made large to catch all hair types, then hair catching performance is improved, but the outer blade cannot smoothly move along skin
Solution Approach 1:
Rather than making all hair inlets uniformly large, the invention implements local quality variations with widened portions at specific locations within the inlets. This allows certain areas to effectively catch hairs of different lengths and directions while other areas maintain smaller profiles that enable smooth blade movement along the skin surface.
4Object-affected harmful factors
If ridges are disposed on the outer blade shaving surface to protect skin, then skin protection is improved, but shaving performance deteriorates
Solution Approach 1:
Instead of adding ridges that create physical barriers, the invention uses a porous-like structure with multiple hair inlets of varying cross-sections. This allows the blade to protect skin by providing multiple pathways for hair entry while maintaining smooth surfaces that do not interfere with shaving performance. The widened portions within the inlets enable effective hair catching without requiring additional protective ridges.
Data Source
Figure 1
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AI summary
A rotary electric shaver 1 includes an outer blade 22 whose upper surface 22a functions as annular shaving surfaces 22A and 22B having multiple hair inlets 27 formed therein, and an inner blade 42 that has a small blade 42A which rotates while coming into sliding contact with a lower surface 22b of the outer blade 22 from below the annular shaving surfaces 22A and 22B. At least a portion of the multiple hair inlets 27 is formed in an elongated hole shape extending along a radial direction of the annular shaving surfaces 22A and 22B, and an end portion 27a (alternatively, both end portions 27a and 27b) in the radial direction has a widened portion 27x (alternatively, 27x and 27y) which is open wider in a circumferential direction than a central portion 27c.