Optical Waveguide Cutting Element for Hair Devices

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Solution Overview

Problem

Current laser-based hair cutting devices are inefficient due to low light coupling from the optical waveguide into hair, as light propagating in lower-order modes tends to remain central and parallel to the waveguide axis, reducing the effectiveness of hair cutting.

Innovation Solution

Incorporating structures along the optical waveguide with a refractive index lower than the waveguide, such as cavities or bubbles, to deflect and scatter light, increasing its angle and coupling into hair at the cutting face, thereby enhancing cutting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser light propagates through the optical waveguide in lower-order propagation modes, then the light propagates nearer to the centre of the optical waveguide and substantially parallel to the optical axis, but this reduces the amount of light coupling out from the waveguide surface into hair

Engineering Contradiction:
Improvecutting effectivenessVSAvoidlight coupling efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent introduces structures with different refractive indices along the optical axis of the waveguide. This changes the optical parameters of the waveguide, causing light to reflect, refract, and scatter at greater angles relative to the optical axis, thereby increasing light coupling into the hair

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses intermediate structures (cavities, voids, or bubbles with different refractive indices) as mediators within the optical waveguide. These structures interact with the propagating light to modify its propagation characteristics, causing it to couple more effectively into the hair at the cutting face

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If structures with lower refractive index are formed along the optical axis, then light reflects, refracts and scatters at greater angles, but this requires additional manufacturing complexity

Engineering Contradiction:
Improvelight coupling efficiencyVSAvoidwaveguide structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies local quality by forming structures with different refractive indices at specific locations along the optical axis of the waveguide. These localized structures (cavities, voids, or bubbles) are positioned strategically to interact with propagating light without requiring complex modification of the entire waveguide structure

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent utilizes porous or void structures within the optical waveguide. The cavities, voids, or bubbles create regions with different refractive indices that scatter and redirect light, achieving enhanced light coupling through a relatively simple structural modification rather than complex material composition changes

Inventive Principle:
Principle #31Porous materials

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

This approach increases the amount of light available at the cutting face, leading to improved cutting effectiveness and reduced time required for hair cutting, minimizing user effort and skin irritation.

Implementation Method 1

a fibre optic is located on a shaving portion of the device that is positioned to receive the laser light from the laser light source at a proximal end, conduct the laser light from the proximal end toward a distal end

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

By forming structures having a lower refractive index along the optical axis, some of the light propagating through the optical waveguide will interact with the structures, causing it to reflect, refract and/or scatter so that it propagates at a greater angle with respect to the optical axis

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

In order to cut or melt hair, sufficient optical energy needs to couple out from a surface of a cutting element of the cutting device into hair to initiate the cutting/melting of hair

Methodology Applied
Scientific EffectOptical energy coupling: Absorption (EM radiation)

Data Source

PatentEP3554408B1A cutting element for a hair cutting device
Publication Date: 2020.04.22 KONINKLIJKE PHILIPS NV
  • EP3554408B1 patent drawingFigure 1
  • EP3554408B1 patent drawingFigure 2
  • EP3554408B1 patent drawingFigure 3

AI summary

There is provided a cutting element for use in a hair cutting device. The cutting element includes an optical waveguide having an optical axis and a sidewall, wherein a portion of the sidewall forms a cutting face for contacting hair; wherein the optical waveguide includes a plurality of structures formed along the optical axis, the structures having a refractive index which is different to a refractive index of the optical waveguide. A hair cutting device comprising a cutting element, and a method of manufacturing an optical waveguide cutting element are also disclosed.