Over-Guard Razor Cartridge for Low-Irritation Stubble Control
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Solution Overview
Problem
Existing razor cartridges cause skin irritation and exacerbate conditions like pseudofolliculitis barbae (PFB) and acne, and fail to maintain a desired '5 o'clock shadow' appearance during shaving.
Innovation Solution
A razor cartridge with an over-guard design featuring angled blades and progressively decreasing heights of longitudinal members, along with enhanced blade sharpness, provides a comfortable shaving experience while maintaining beard length for a permanent shadow look.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional razor cartridges are used to achieve a close shave, then shaving completeness is improved, but skin irritation and worsening of PFB/acne conditions occur
Solution Approach 1:
The cartridge is divided into functional zones: a skin protection zone with the over-guard that prevents blade contact with skin, and a hair cutting zone with multiple blades positioned to cut hair before it contacts the skin. This segmentation allows effective hair removal while preventing the harmful effect of blade-on-skin irritation.
Solution Approach 2:
The over-guard acts as an intermediary element between the blades and the skin. It is positioned in advance of the first blade and extends beyond the last blade, creating a protective barrier that prevents direct contact between the blade edges and the skin surface, thereby eliminating irritation while maintaining shaving effectiveness.
2Productivity
If traditional razor cartridges are used to remove all hair, then shaving completeness is improved, but the desired '5 o'clock shadow' appearance is lost
Solution Approach 1:
The over-guard creates a partial shaving action by blocking the path of the last blade from contacting the skin. This allows the first and second blades to cut hair, but the over-guard prevents complete removal, leaving a controlled amount of stubble that maintains the desired 5 o'clock shadow appearance while still providing effective hair management.
3Productivity
If blade angle is increased to improve cutting efficiency, then shaving effectiveness is improved, but skin irritation increases
Solution Approach 1:
The over-guard serves as a mediator that decouples the blade angle from its harmful effect on skin. Even with optimized blade angles for cutting efficiency, the over-guard ensures the blade edges never contact the skin, allowing aggressive blade geometry to be used without causing irritation.
Data Source
AI summary
A razor cartridge has a housing with a blade mounting region between a guard and a cap. A first, second and third razor blade are sequentially mounted in the blade mounting region. An over-guard is secured over the blades. The cutting edges of the blades have an as-defined increased sharpness. The blades are mounted at a reduced angle between each blade portion bearing the cutting edge and a reference plane tangential to the cutting edges of the first and third blade. Individual longitudinal members of the over-guard that lie over each blade and have a progressively decreasing height above the reference plane in a front to back direction of the razor cartridge. A further longitudinal member is forward of the first blade and has a height above the reference plane.