Razor Cartridge Pivot Axis Positioning for Skin Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing razor cartridges with a single defined pivot axis struggle to maintain optimal contact with non-planar skin surfaces when equipped with four or more blades, due to varying forces during shaving, leading to undesirable effects like chatter or loss of contact.
Innovation Solution
A razor cartridge design with a pivot axis positioned rearward of the midpoint and below a tangent plane defined by the guard and cap structures, featuring arcuate bearing surfaces and a spring-biased cam follower for resilient movement, allowing optimal contact and reduced chatter during shaving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single defined pivot axis is used in a razor cartridge, then the structure is simple and easy to manufacture, but the cartridge cannot maintain optimal contact with non-planar skin surfaces when equipped with four or more blades
Solution Approach 1:
The single pivot axis is segmented into two separate pivot axes positioned at opposite ends of the cartridge (near the guard and cap structures). This segmentation allows independent rotation of the cartridge about each axis, enabling the cartridge to adapt to non-planar skin surfaces while maintaining structural simplicity through the use of standard pivotal connection structures at each end.
Solution Approach 2:
The pivot connection is extended from one dimension (single axis) to two dimensions by adding a second pivot axis perpendicular to the first. This creates a ball-and-socket-like configuration that allows the cartridge to pivot in multiple directions, significantly improving its ability to conform to non-planar skin surfaces while accommodating four or more blades.
2Productivity
If four or more razor blades are disposed within the cartridge housing, then shaving coverage is improved, but forces applied to the cartridge during shaving become highly variable causing chatter or loss of contact
Solution Approach 1:
The cartridge is designed with dynamic pivot capability, allowing it to rotate about two perpendicular axes during shaving. This dynamic adjustment enables the cartridge to automatically compensate for variable forces caused by four or more blades, skin type variations, and user pressure differences, maintaining stable contact without chatter or loss of contact.
Solution Approach 2:
The pivot axes are positioned with specific parameters (rearward of the midpoint and below the tangent plane defined by guard and cap structures) to optimize the distribution of forces across four or more blades. This parameter optimization balances the moments acting on the cartridge, ensuring reliable contact stability while maintaining high shaving coverage efficiency.
3Ease of operation
If the pivot axis is positioned at the conventional location, then the structure is simplified, but moments applied to the cartridge cause chatter or rotation away from the skin surface
Solution Approach 1:
The pivot axes are positioned asymmetrically relative to the cartridge center, specifically rearward of the midpoint and below the tangent plane. This asymmetric positioning creates a balanced moment distribution that prevents chatter and unwanted rotation, improving shaving smoothness while the symmetric arrangement of two perpendicular axes maintains reasonable structural simplicity.
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 optimized pivot axis location and spring-biased mechanism ensure the razor cartridge maintains consistent contact with the skin, improving shaving performance by balancing moments and accommodating varying forces effectively.
Implementation Method 1
a spring element projecting from the handle and contacting the cartridge
Implementation Method 2
The arcuate bearing surfaces slidably engage pivoting connecting structure of a handle
Data Source
Figure 1
Figure 2
Figure 3~3B
AI summary
A safety razor is provided comprising a razor cartridge (10) mounted on pivoting connecting structure (102) of a handle (100). The razor cartridge has four or more razor blades (70). The pivot axis of the razor cartridge is rearward of the midpoint of the cartridge width (52) and below a plane (50) tangent to the guard and cap structures of the housing (12) of the razor cartridge.