Tactile Wear Indicator Coating for Hair Cutting Elements

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Solution Overview

Problem

Existing hair cutting devices, such as razors and electric shavers, lack effective means to indicate blade wear other than visual indicators, which may not be noticed by the user, leading to reduced cutting performance and increased hair pulling.

Innovation Solution

A cutting element with a tactile wear indicator comprising a wearable outer layer of coating material containing a dry lubricant additive, which reduces friction during use and provides a tactile sensation as it wears, indicating blade wear through increased friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a visual wear indicator is used to indicate blade wear, then the user can see the wear status, but the user may not notice the indicator until the blade is already worn and causing pain

Engineering Contradiction:
Improvewear indication informationVSAvoidtime to detect wear
Core Design Contradiction:
Loss of informationVSLoss of time

Solution Approach 1:

The wear indicator is segmented into multiple layers with different friction characteristics. The outer layer has low friction (smooth sensation) while the inner layer has high friction (rough sensation). As the outer layer wears away, the user experiences a tactile transition from smooth to rough, providing timely wear detection without relying on visual inspection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the visual indication system with a tactile indication system. Instead of relying on visual wear indicators that require the user to look at the device, the invention uses friction-based tactile feedback that the user feels during normal operation. This substitution of the sensing modality from visual to tactile ensures continuous wear monitoring.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the cutting element provides low friction for smooth gliding, then user comfort is improved, but it becomes difficult to detect blade wear through friction changes

Engineering Contradiction:
Improvegliding smoothnessVSAvoidwear detection sensitivity
Core Design Contradiction:
Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The wear indicator incorporates localized regions with different friction properties. The outer layer provides low friction for smooth gliding comfort, while the inner layer provides high friction for wear detection. This local quality differentiation allows the system to simultaneously achieve user comfort during operation and sensitive wear detection when the outer layer wears away.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the friction parameter of the wear indicator layers to create detectable tactile feedback. The outer layer is designed with low friction coefficient for smooth operation, while the inner layer has high friction coefficient. As wear progresses, the friction parameter transitions from low to high, providing a clear tactile signal of blade wear while maintaining smooth gliding during the functional life of the blade.

Inventive Principle:
Principle #35Parameter changes

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 tactile wear indicator offers a reliable and user-friendly method to detect blade wear by changing friction levels, enhancing cutting performance and user comfort.

Implementation Method 1

the wearable outer layer comprising a coating material having a dry lubricant additive

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 2

reduce the friction between the cutting element and the skin of a user during a cutting stroke

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

configured to wear away (e.g. by abrasion or otherwise) over time, e.g. as it is brought into sliding contact with the skin of the user

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP4188655B1Tactile wear indicator for a cutting element
Publication Date: 2025.11.19 KONINKLIJKE PHILIPS NV
  • EP4188655B1 patent drawingFigure 1
  • EP4188655B1 patent drawingFigure 2
  • EP4188655B1 patent drawingFigure 3a~3c

AI summary

There is described a cutting element (106) for a hair cutting device (100). The cutting element (106) comprises a tactile wear indicator (140) that defines a skin-contact surface of the cutting element (106). The tactile wear indicator (140) comprises a wearable outer layer (148) of coating material having a dry lubricant additive (150).