Movable Lens Liquid Detection for High-Output Light Fixtures

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Solution Overview

Problem

Existing light fixtures, particularly moving head light fixtures, face challenges in maintaining high light output and minimizing internal reflections when exposed to moisture or objects on the lens, often requiring complex sealing solutions that increase friction, noise, and decrease lighting quality.

Innovation Solution

A light fixture design with a movable lens and electric motor system that detects the presence of liquid or objects on the lens by monitoring motor current, using a control unit to adjust the lens position to remove liquid via gravity, eliminating the need for additional sealing windows and reducing internal reflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a window is arranged in front of the lens to protect it and decrease moisture ingress risk, then the lens is protected and moisture risk is decreased, but internal reflections increase, light output decreases, and weight increases

Engineering Contradiction:
Improvemoisture protectionVSAvoidlight output
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent removes the protective window element from the system. Instead of using a window to protect the lens, the invention relies on the housing structure and sealing at the head to protect internal components, allowing the lens to be exposed without a window in front of it, thereby eliminating internal reflections and maintaining light output.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a liquid detection and removal system as an intermediary mechanism. The control unit detects liquid presence on the lens and activates the drive mechanism to reposition the lens, using the housing structure as an intermediary to shed liquid through gravity, thus protecting the lens function without requiring a physical window barrier.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a window is arranged in front of the lens to protect it, then the lens is protected, but the window adds weight to the moving head light fixture

Engineering Contradiction:
Improvelens protectionVSAvoidmoving head light fixture weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts and removes the window component from the moving head light fixture. By eliminating the window, the weight of the moving assembly is reduced, while lens protection is achieved through alternative means such as housing design and liquid detection/removal systems that do not add significant weight to the moving components.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If special sealings and hydrophobic grease are used at joints to protect against water, then ingress protection is improved, but friction and noise increase

Engineering Contradiction:
Improveingress protectionVSAvoidjoint friction and noise
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces mechanical sealing solutions (special sealings and hydrophobic grease at moving joints) with an electronic detection and active response system. The control unit detects liquid presence and the drive mechanism actively repositions the lens to shed liquid, substituting passive mechanical sealing with an active electronic control system that avoids adding friction and noise to moving joints.

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

4Illumination intensity

If the lens is exposed without a window to maintain high light output, then light output is maximized, but the risk of liquid or objects on the lens increases

Engineering Contradiction:
Improvelight outputVSAvoidliquid presence on lens
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback control system where the control unit continuously monitors for liquid presence on the lens and automatically activates the drive mechanism to reposition the lens when liquid is detected. This closed-loop feedback system maintains high light output by keeping the lens exposed while actively managing the risk of liquid contamination through real-time detection and response.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The lens protection system operates autonomously without requiring external intervention. The control unit self-detects liquid presence and the drive mechanism self-activates to reposition the lens for liquid removal, creating a self-service protection system that maintains optimal optical performance while autonomously managing contamination risks.

Inventive Principle:
Principle #25Self-service

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 system effectively detects and removes liquid or objects on the lens, maintaining high light output and reducing internal reflections, while minimizing mechanical stress and complexity, thus enhancing the light fixture's durability and performance.

Implementation Method 1

an electric motor configured to move the lens relative to the light source in direction of the main light emission direction

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a control unit configured to determine a current used by the electric motor to move the lens in the main light emission direction and the control unit is configured to detect a presence of liquid on the lens based on the determined current

Methodology Applied
Scientific EffectElectrical resistance change due to added mass: Electrical Resistance

Implementation Method 3

using a control unit to adjust the lens position to remove liquid via gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4650655A1Light fixture with liquid detection
Publication Date: 2025.11.19 MARTIN PROFESSIONAL
  • EP4650655A1 patent drawingFigure 1
  • EP4650655A1 patent drawingFigure 2
  • EP4650655A1 patent drawingFigure 3

AI summary

The application relates to a light fixture comprising a compartment housing at least one light source configured to emit light in a main light emission direction. A lens is provided movably arranged relative to the light source in direction of the main light emission direction, and an electric motor configured to move the lens relative to the light source in direction of the main light emission direction. A control unit determines a current used by the electric motor to move the lens in the main light emission direction, wherein the control unit is configured to detect a presence of a liquid on the lens based on the determined current.