Safety Razor Blade Unit with Convex Lubricating Pad
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Solution Overview
Problem
Conventional safety razor blade units with rectangular or block-type shapes are inefficient for shaving contoured, smaller skin areas such as around the ankles, behind the knees, and under the arms, as they tend to cause friction and minor cuts due to inadequate lubrication and poor adaptation to curved surfaces.
Innovation Solution
A blade unit design featuring a convex lubricating pad and an elongate lubricating strip that together cover at least 60% of the outer perimeter, with the convex pad extending at least 30%, providing enhanced lubrication and reducing friction, and a pivoting mechanism allowing the blade unit to adapt to curved skin surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rectangular or block-type blade unit is used, then it provides good performance for shaving flat, large skin surface areas, but it causes friction and minor cuts when used on contoured, smaller skin surface areas
Solution Approach 1:
The blade unit employs a convex lubricating pad with a curved surface that conforms to the contours of the skin, replacing the traditional flat rectangular design. This curvature allows the lubricating elements to adapt to contoured skin surfaces such as around the ankles, behind the knees, and under the arms, reducing friction and preventing minor cuts while maintaining effective lubrication delivery.
Solution Approach 2:
The invention distributes lubricating elements (convex lubricating pad and elongate lubricating strip) strategically around the outer perimeter of the blade unit, with the convex pad providing greater skin-contacting surface area than the elongate strip. This localized quality enhancement ensures adequate lubrication is delivered precisely where needed on contoured surfaces, addressing the specific problem of friction and cutting on curved skin areas.
2Reliability
If the skin-contacting surface of the lubricating aid behind the cutting edges is made relatively greater, then more lubricant is delivered to the skin while minimising blade clogging, but the blade unit size and volume increase
Solution Approach 1:
The convex lubricating pad utilizes a curved, domed surface geometry that maximizes skin-contacting area within a compact volume. The curvature allows the pad to extend along a significant portion of the outer perimeter without linearly increasing the blade unit's overall size, as the three-dimensional form efficiently packs the lubricating surface area into a space-efficient configuration.
Solution Approach 2:
The invention changes the geometric parameters of the lubricating elements, specifically creating a convex pad with a curved surface that provides greater skin-contacting area relative to its volume. This parameter optimization allows the blade unit to deliver adequate lubrication while maintaining a reasonable format and size, avoiding excessive volume increase.
3Object-affected harmful factors
If lubricating elements cover a majority of the outer perimeter, then friction is reduced and cutting performance is improved, but the blade unit becomes more complex
Solution Approach 1:
The invention merges the convex lubricating pad and elongate lubricating strip into an integrated lubrication system that works together to cover the outer perimeter. The cap and guard are designed as unified structures that hold both lubricating elements, reducing the number of separate components and simplifying the overall blade unit construction while still achieving comprehensive lubrication coverage.
Solution Approach 2:
The cap and guard structures serve multiple functions: they protect the blades, hold the lubricating elements (convex pad and elongate strip), and provide structural support for the blade unit. This multi-functionality reduces the need for additional separate components, maintaining structural simplicity while achieving comprehensive lubrication coverage for reduced friction and improved cutting performance.
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 minimizes cuts and pulling of hair by delivering more lubricant and reducing friction, allowing for effective shaving of contoured areas with a compact and smooth blade unit that easily follows skin contours.
Implementation Method 1
the guard including an elongate lubricating strip, and the cap including a convex lubricating pad... providing enhanced lubrication and reducing friction
Data Source
AI summary
Disclosed is a blade unit for a safety razor, comprising 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; and a guard in front of the cutting edges and a cap to the rear of the cutting edges, the guard including an elongate lubricating strip, and the cap including a convex lubricating pad having a convex skin-contacting surface and a rear edge curved in a single arc shape along its entirety. A skin-contacting surface of the convex lubricating pad is greater than a skin-contacting surface of the elongate lubricating strip, the convex lubricating pad and the elongate lubricating strip together extend along at least 60% of an outer perimeter of the blade unit, and the convex lubricating pad extends along at least 30% of the outer perimeter of the blade unit.