Shaving Razor Handle Geometry and Progressive Biasing
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Solution Overview
Problem
Conventional shaving razors often fail to maintain the blade unit flat against the skin during shaving, leading to reduced closeness and comfort due to limited pivotability and handle instability, which requires additional user effort to compensate for the top-heavy design.
Innovation Solution
A shaving razor with a biasing member that provides a progressively increasing return torque to keep the cartridge flat against the skin and a handle geometry that balances the razor, reducing the propensity for rolling and improving maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the blade unit is designed with limited pivotability about a single axis, then the device complexity is reduced, but the cartridge fails to remain flat against the skin during shaving
Solution Approach 1:
The patent introduces a dynamic two-axis pivot system that allows the cartridge to rotate about a first axis (longitudinal axis parallel to cutting edges) and a second axis (transverse axis perpendicular to cutting edges). This dynamic multi-axis capability enables the cartridge to adapt to skin contours while maintaining flat contact, resolving the contradiction between simple single-axis design and reliable flat contact.
2Ease of operation
If the handle longitudinal axis is offset from the razor cartridge behind the cartridge, then the cartridge is pushed through the shaving stroke, but the razor becomes unstable and requires additional user effort to control
Solution Approach 1:
The patent employs asymmetric handle geometry where the longitudinal axis is offset from the cartridge, creating a deliberate top-heavy configuration. This asymmetric design shifts the center of gravity forward, which initially appears unstable but actually provides directional stability during the shaving stroke, allowing the cartridge to be pushed through the stroke with controlled instability that enhances cutting performance.
3Reliability
If a conventional biasing member with low spring force is used, then the cartridge is prevented from lifting off the skin, but the cartridge cannot be forced into flat contact with the skin during shaving strokes
Solution Approach 1:
The patent replaces the conventional static low-force spring biasing system with a dynamic progressive spring mechanism. This progressive spring provides increasing biasing force as the cartridge pivots away from the skin, dynamically adapting the force level to maintain flat contact during shaving strokes while preventing lift-off during transitions, thereby resolving the contradiction between sufficient contact force and controlled cartridge positioning.
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 solution ensures a closer, more comfortable shave by maintaining the cartridge flat and enhancing user control through improved stability and balance, reducing the effort required to maintain the razor's stability during use.
Implementation Method 1
a biasing member extending outwardly from the handle and having an end which when the cartridge is coupled to the handle is in sliding engagement between the neutral and fully-rotated positions. The biasing member exerts a variable torque against the abutment surface.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A shaving razor that improves stability, corresponding user control and offers a closer shave is provided. The shaving razor can include a razor handle configuration that reduces the propensity for the shaving razor to roll in a users hand and improves the maneuverability of the razor cartridge during shaving. In addition, the shaving razor can include a biasing pivoting member producing a progressively increasing return torque on the razor cartridge that forces the cartridge into flat contact with the skin thus improving glide and shaving closeness.