Guard Tooth Geometry for Skin Deflection in Haircutting Blades

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Solution Overview

Problem

Existing guard elements in hair cutting devices are bulky, provide inadequate skin protection, and cause skin irritation and discomfort during haircutting due to suboptimal design.

Innovation Solution

The guard tooth and cutter tooth configurations feature a specific angle between tangent lines of the cutter blade and elevated portion top surface, deflecting the skin away from the cutter blade, thereby preventing skin bulging and enhancing hair cutting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If known guard elements are used to space apart cutter teeth from the skin, then skin protection is provided, but the guard elements are bulky and adversely impact hair cutting efficiency

Engineering Contradiction:
Improveskin protectionVSAvoidhair cutting efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The guard tooth features a localized elevated portion at its distal end that specifically addresses skin protection at the critical interface with the skin, while the rest of the guard tooth maintains a streamlined profile to minimize impact on hair cutting efficiency. This local modification provides targeted protection without the bulkiness of conventional guard elements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention modifies the geometric parameters of the guard tooth by creating an elevated portion with specific dimensional characteristics (height, length, and angular relationships) that optimize both skin protection and hair cutting performance. The angle between the elevated portion surface and the cutter blade running surface is specifically designed to deflect skin away from the cutter blade.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If known guard elements are used to protect skin, then some skin protection is provided, but they cause skin irritation and discomfort during haircutting

Engineering Contradiction:
Improveskin protectionVSAvoidskin irritation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The elevated portion is strategically positioned at the distal end of the guard tooth where it directly interfaces with the skin, providing localized protection and skin deflection exactly where needed to prevent irritation, while the remainder of the guard tooth structure maintains smoothness and comfort during operation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The elevated portion is designed with curved surfaces that smoothly deflect the skin away from the cutter blade. The curved geometry of the elevated portion top surface and its angular relationship with the cutter blade running surface create a gentle skin deflection path that prevents sharp edges from causing irritation or discomfort.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If the guard tooth has a specific angle configuration with the elevated portion, then skin deflection is improved and skin bulging is prevented, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveskin deflectionVSAvoidangle precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention specifies particular angular parameters for the elevated portion (first angle between 0°-5°, second angle between 10°-45°) that optimize skin deflection. These parameter specifications provide clear manufacturing targets that balance effective skin protection with achievable manufacturing precision, avoiding overly complex angular requirements while maintaining functional effectiveness.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4711105A1Guard tooth and cutter tooth for a haircutting device
Publication Date: 2026.03.18 KONINKLIJKE PHILIPS NV
  • EP4711105A1 patent drawingFigure 1
  • EP4711105A1 patent drawingFigure 2
  • EP4711105A1 patent drawingFigure 3

AI summary

It is presented a guard tooth (21) for a guard blade (20) of a hair cutting device (100), the guard tooth (21) extending in a lateral direction (L) from the guard blade (20) and comprising: a first guard tooth portion (25) connectable to a guard blade base portion (27), and a second guard tooth portion (29) extending from the first guard tooth portion (25) in the lateral direction (L), wherein the first guard tooth portion (25) comprises a cutter blade running surface (23) adapted to face a cutter blade (10) arrangeable above the guard blade (20) for at least partially contacting the cutter blade running surface (23) with a cutter blade contact surface (13), wherein the second guard tooth portion (29) comprises an elevated portion (63) extending in the lateral direction (L) from the cutter blade running surface (23) and in a height direction (H) perpendicular to the lateral direction (L), wherein a first angle (37) between a first tangent line (31) of a cutter blade top surface (33) opposite to the cutter blade contact surface (13), representing the slope of the cutter blade top surface (33), and a second tangent line (35) between an elevated portion top surface (39) and the cutter blade top surface (33) is smaller than 5°.