Scalp Light Output Control With Photodiode Feedback

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Solution Overview

Problem

Existing scalp care devices do not effectively adapt their operations to the user's hair loss condition or scalp condition, leading to inefficient and potentially harmful treatments.

Innovation Solution

A light outputting device with integrated sensors and processors that adjust light source operation based on user-specific hair loss type, scalp temperature, humidity, and condition, using laser light sources and LEDs to provide targeted scalp care.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fixed light intensity is used for scalp care, then device structure is simple, but treatment efficiency cannot be optimized for different hair loss conditions

Engineering Contradiction:
Improvetreatment efficiencyVSAvoiddevice structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic adjustment of light intensity by equipping each laser light source with a photodiode that provides real-time feedback on light output. The processor continuously monitors these signals and adjusts the driving current to each laser source individually, enabling the system to adapt to varying scalp conditions and hair loss severity, thereby optimizing treatment efficiency while managing device complexity through intelligent control.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates feedback mechanisms where photodiodes associated with each laser light source monitor the actual light output in real-time. This feedback signal is processed to determine the appropriate light intensity level, which is then used to adjust the driving current. This closed-loop control system ensures optimal treatment delivery while automatically adapting to individual user needs, resolving the contradiction between treatment efficiency and device complexity.

Inventive Principle:
Principle #23Feedback

2Productivity

If high light intensity is applied to promote hair growth, then treatment effectiveness increases, but risk of scalp damage increases

Engineering Contradiction:
Improvehair growth promotionVSAvoidscalp damage risk
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses photodiodes to continuously monitor the actual light intensity being delivered to the scalp. This real-time feedback allows the processor to detect any deviations from safe intensity levels and immediately adjust the driving current to prevent overheating or tissue damage. The system thus maintains therapeutic effectiveness while automatically preventing harmful effects through continuous monitoring and adaptive control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the operating parameters (light intensity, duty cycle) of the laser sources based on real-time conditions. By adjusting these parameters according to scalp response and individual user profiles, the system maximizes hair growth promotion while staying within safe thermal and biological limits, thereby resolving the contradiction between treatment effectiveness and safety.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If individualized light intensity adjustment is implemented for each laser light source, then treatment precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvelight intensity control precisionVSAvoidnumber of photodiodes and control circuits
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the scalp treatment area into multiple zones, each served by separate laser light sources with individual photodiodes and control circuits. This segmentation allows independent optimization of light intensity for different scalp regions based on local hair loss conditions. The modular architecture manages complexity by creating reusable, standardized control units that can be systematically deployed across multiple zones.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a universal control architecture where the processor manages multiple laser sources and photodiodes through a unified feedback control algorithm. This multi-functional approach allows the same control logic to be applied across all light sources, reducing overall system complexity despite the increased number of components. The system thus achieves precise individualized control while maintaining manageable device architecture through standardized, reusable control patterns.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 device provides optimized scalp care by adjusting light intensity and operation based on real-time scalp conditions, enhancing hair growth and preventing damage, while minimizing risks to the user.

Implementation Method 1

a photodiode configured to be provided in each of the plurality of laser light sources

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

Laser light used as a low level laser therapy generates effects such as an increase in capillary production, an increase in blood oxygen concentration, and promotion of collagen production by penetrating into a living tissue and activating ions of cells

Methodology Applied
Scientific EffectLaser: Laser

Data Source

PatentEP4000686B1Light outputting device for scalp care
Publication Date: 2025.11.19 LG ELECTRONICS INC
  • EP4000686B1 patent drawingFigure 1
  • EP4000686B1 patent drawingFigure 2
  • EP4000686B1 patent drawingFigure 3

AI summary

A light outputting device for scalp care according to an embodiment of the present disclosure includes a dome-shaped outer case configured to form an outer appearance, an inner case configured to be formed inside the outer case, a plurality of laser light sources configured to be disposed in a space between the outer case and the inner case, a photodiode configured to be provided in each of the plurality of laser light sources, and a processor configured to obtain a light amount sensing value of a first photodiode among a plurality of photodiodes, based on the obtained light amount sensing value, to set the light amount for the first laser light source including the first photodiode, and to drive the first laser light source based on a set amount of light.