Safety Razor Blade Unit with Curved Back for Contoured Shaving
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Solution Overview
Problem
Conventional safety razor blade units with rectangular or block-type shapes are inadequate for shaving contoured skin areas such as the ankles, behind the knees, and under the arms, as they do not effectively accommodate curved surfaces.
Innovation Solution
A blade unit design featuring a non-flexible concave back portion with a convex lubricating pad that arcs away from the shaving plane, providing a larger skin-contacting surface while maintaining a compact size, and an elongate lubricating strip on the front edge to minimize friction and prevent clogging, along with a pivoting mechanism for enhanced maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rectangular or block-type blade unit shape is used, then good shaving performance on flat, large skin surface areas is achieved, but effective shaving on contoured, smaller, narrower skin surface areas becomes problematic
Solution Approach 1:
The blade unit incorporates a concave back portion with a specific radius of curvature (5-20mm) that allows the blade unit to conform to curved skin surfaces. This curvature enables effective shaving on contoured areas such as ankles, behind knees, and under arms, while maintaining a compact overall shape.
Solution Approach 2:
The invention transitions from a planar, rectangular blade unit design to a three-dimensional curved design by introducing a concave back portion. This dimensional change allows the blade unit to adapt to the curvature of various skin surfaces, expanding its versatility across different body areas.
2Adaptability or versatility
If the skin-contacting surface area is increased to accommodate curved surfaces, then effective shaving on contoured areas is improved, but the size and volume of the blade unit increases
Solution Approach 1:
By curving the back portion of the blade unit with a radius of 5-20mm, the design increases the skin-contacting surface area without proportionally increasing the overall volume. The curved geometry allows better conformity to skin contours while maintaining a compact blade unit suitable for maneuverability.
3Strength
If a separate frame element is added around the outer perimeter of the blade unit for fixing elements, then structural integrity is improved, but the skin-contacting surface area is reduced and frame edges may disturb the shaving process
Solution Approach 1:
The frame element is merged with the concave back portion, eliminating the need for a separate peripheral frame. This integration maintains structural integrity for fixing blade unit elements while maximizing the skin-contacting surface area and avoiding disturbance to the shaving process.
Solution Approach 2:
The concave back portion serves multiple functions: it provides structural support for fixing blade elements, creates the necessary curvature for skin conformity, and eliminates the need for a separate frame that would reduce skin contact area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for effective shaving of contoured skin areas with reduced friction and minor cuts, improved lubrication, and increased comfort by maximizing skin-contacting surface area and accommodating curved surfaces.
Implementation Method 1
the lubricating pad can be deformed by, for example, a compressive force. The lubricating pad can return substantially to its shape prior to deformation.
Data Source
AI summary
Embodiments of the invention include a blade unit for a safety razor, comprising: a connecting structure configured to fix the blade unit to a handle; a blade housing comprising a plurality of blades having respective cutting edges lying in a shaving plane and being arranged to exert a cutting action when moved across a user's skin in a shaving direction; and a rear portion arranged next to the plurality of blades in the shaving direction, comprising a non-flexible concave back portion that arcuately bends away from the shaving plane, and a convex lubricating pad arranged on and being supported by the non-flexible concave back portion and which extends up to a rear edge of the rear portion of the blade unit.