Active Anti-Fog Lens with Localized Joule Heating
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Solution Overview
Problem
Conventional anti-fog systems for eyewear lenses are inefficient in rapidly clearing condensed vapor, as they uniformly distribute heat across the lens, leading to slow defogging and potential obstruction of the user's line of sight.
Innovation Solution
An active anti-fog (AAF) lens system that preferentially heats the area in front of the user's eyes, using a conductive layer with electrodes and a power source to rapidly clear condensation, with the first region generating heat faster than other areas, ensuring clear vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If uniform heating is applied across the lens, then the entire lens surface is heated evenly, but the clearing speed of condensed vapor is slow and the user's line of sight may be obstructed
Solution Approach 1:
The patent applies local quality by creating a non-uniform heating pattern where the central region (corresponding to the user's line of sight) receives higher heating power than the peripheral regions. This is achieved through electrode positioning and geometry that concentrates current density in the central area, enabling rapid clearing of condensation from the critical viewing zone while maintaining moderate heating elsewhere.
2Speed
If heating power is concentrated in a selected portion of the lens, then clearing speed of condensed vapor is improved, but hot spots may form in the heating elements
Solution Approach 1:
The patent employs dynamics by making the heating pattern adjustable and controllable. The system can dynamically adjust the distribution of heating power across different regions of the lens, allowing optimization between clearing speed and hot spot prevention based on operational conditions. This includes controllable electrode activation and power distribution that adapts to prevent localized overheating.
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 AAF lens system effectively clears condensation from the critical viewing area within 120 seconds or less, maintaining a clear line of sight and enhancing situational awareness by prioritizing heating of the lens region directly in front of the user's eyes.
Implementation Method 1
electric current is passed for electrically resistive heating to increase a temperature of a lens and thereby dissipate condensed moisture from the lens
Data Source
AI summary
An active anti-fog eyewear system includes a lens with a conductive layer and a power source to provide an electrical current to the conductive layer. When the current is provided to the conductive layer, the conductive layer generates heat. A portion of the conductive layer that is positioned in front of the eyes of a wearer of the eyewear, and a corresponding portion of the lens, is heated more rapidly than other portions of the conductive layer and lens. Condensed water vapor is rapidly cleared from the portion of lens that is positioned in front of the wearer’s eyes. The lens can include electrodes positioned near the top of the lens to direct the current to the portion of the conductive layer that is positioned within a line of sight of the wearer.