Hair Cutting Device with Optical Waveguide Light Feedback
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Solution Overview
Problem
Laser-based hair cutting devices face safety issues due to the risk of skin irritation or burning when high-powered light is used to cut hair, as it can couple into the skin and cause damage.
Innovation Solution
A hair cutting device with an optical waveguide that measures light levels to differentiate between hair and skin contact, adjusting the light power accordingly to prevent skin damage while maintaining effective hair cutting, using a control unit and light sensors to manage the power of the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-powered light is used to cut hair, then hair cutting effectiveness is improved, but skin safety deteriorates due to risk of burning or irritation
Solution Approach 1:
The light power is dynamically adjusted based on real-time feedback from the light sensor. When hair is detected (high light absorption), high power is applied for effective cutting. When skin is detected (low light absorption), power is reduced to safe levels, preventing burns while maintaining cutting effectiveness throughout the shaving process
Solution Approach 2:
A light sensor provides continuous feedback about the optical properties of the material being contacted. The control unit processes this feedback signal and adjusts the light source power accordingly, creating a closed-loop control system that automatically differentiates between hair and skin and adjusts power to achieve effective hair cutting while preventing skin damage
2Productivity
If the cutting element is brought very close to the skin, then hair cutting effectiveness is improved, but skin safety deteriorates due to increased risk of light coupling into skin
Solution Approach 1:
The light sensor continuously monitors the optical characteristics of the contacted material, providing real-time feedback that enables the control system to distinguish between hair and skin even when the cutting element is in close contact with the skin surface, allowing safe operation at optimal cutting distances
Solution Approach 2:
The system changes the power parameter of the light source based on detected material properties. By adjusting light power according to the optical absorption characteristics detected by the sensor, the system maintains close contact for effective shaving while preventing harmful light coupling into skin through adaptive power modulation
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 reduces the risk of skin irritation and maintains effective hair cutting by controlling the light power based on measured light levels, ensuring safe operation and efficient hair removal.
Implementation Method 1
an optical waveguide that is coupled at a first end to the light source to receive light
Implementation Method 2
a light source for generating light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in or on hair
Implementation Method 3
a light sensor that is coupled to the optical waveguide away from the first end, wherein the light sensor is for measuring the light level in the optical waveguide
Data Source
AI summary
There is provided a hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising a light source for generating light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in or on hair; a cutting element that comprises an optical waveguide that is coupled at a first end to the light source to receive light, wherein a portion of a sidewall of the optical waveguide forms a cutting face for contacting hair; a light sensor that is coupled to the optical waveguide away from the first end, wherein the light sensor is for measuring the light level in the optical waveguide and for providing an output signal representing the measured light level; and a control unit that is coupled to the light source, and coupled to the light sensor to receive the output signal, wherein the control unit is configured to determine a measure of the amount of input light transmitted across the optical waveguide from the measured light level and an input light level at the first end of the optical waveguide; and to control the power of the light generated by the light source based on the determined measure.