Rotary Shaver Outer Cutter Aperture Density Variation
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Solution Overview
Problem
Rotary electric shavers face challenges in increasing shaving area and preventing excessively close shaving, which can damage the skin, especially on uneven surfaces or when firm pressure is applied, due to limited design configurations of existing annular shaving faces and aperture densities.
Innovation Solution
The rotary electric shaver features a plurality of concentric annular shaving faces on the outer cutter with varying hair-entry aperture densities in the circumferential direction, allowing for increased shaving area and reduced risk of skin damage by alternating aperture densities as the cutter moves over the skin, with higher densities on the outer peripheral side and lower on the inner peripheral side to manage contact pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple annular shaving faces are provided to increase the shaving area, then the shaving efficiency is improved, but the contact pressure on the inner annular shaving face increases causing excessively close shaving and skin damage
Solution Approach 1:
The patent applies different aperture densities to different regions of the shaving faces. The outer annular shaving face has a first aperture density while the inner annular shaving face has a second aperture density that is lower than the first. This local differentiation allows the outer face to provide efficient shaving while the inner face reduces contact pressure to prevent skin damage.
Solution Approach 2:
The outer cutter is segmented into multiple independent annular shaving faces (outer and inner), each with distinct aperture density characteristics. This segmentation allows each face to perform its specific function - the outer face for primary shaving and the inner face for pressure reduction and skin protection.
2Manufacturing precision
If the outer cutter is pressed firmly against the skin surface to improve shaving closeness, then the shaving quality is improved, but the skin is damaged due to excessively close shaving
Solution Approach 1:
The patent creates a local quality difference in aperture density between the outer and inner annular shaving faces. The outer face maintains higher aperture density for effective hair cutting, while the inner face has lower aperture density to reduce contact pressure and prevent skin damage even when firm pressure is applied.
3Productivity
If the aperture density is increased to improve shaving efficiency, then the shaving speed is improved, but the risk of skin damage increases due to higher contact pressure
Solution Approach 1:
The patent implements local quality differentiation by setting the aperture density of the outer annular shaving face higher than that of the inner annular shaving face. This allows the outer face to deliver high-speed shaving performance while the inner face provides a low-pressure zone that protects the skin from damage.
Data Source
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AI summary
A rotary electric shaver includes an outer cutter which has an upper surface with annular shaving faces, in which many hair-entry apertures are formed, and an inner cutter having small blades, which rotate in sliding contact with the lower surface of the outer cutter from below the shaving faces. The outer cutter (10) has a plurality of concentric annular shaving faces (16, 18), which are integrally formed therewith. The density of the hair-entry apertures (65) is varied in the circumferential direction of the plurality of annular shaving faces (16, 18). The rotary electric shaver increases the shaving area of the outer cutter to improve shaving efficiency and also restrains excessively close shaving thereby to protect skin even when the contact pressure of an area near the center of the outer cutter against skin increases.