IP Camera Gore-Tex透氣薄膜應用與濕氣造成起霧問題解析

Abstract

主要內容以介紹說明IP Camera之未來應用與發展趨勢，並與傳統監視器CCTV之比較說明方式來說明其產品上的不同特性，並以實際之IP Camera產品所應用到的Gore-Tex透氣薄膜所產生的起霧現象分析，藉以說明現有防止起霧方法的適用性，並探討解決起霧現象的有效對策。其中Gore-Tex透氣薄膜製程方法與主要成份ePTFE材質特性，以實際應用到的透氣薄膜型號GAW324，此型號的薄膜主要特殊用途是作為麥克風防水收音孔的防水需求運用，其空氣流通率可達5 ，且薄膜本身防水等級可達IP67，所以經常使用於要求防水又需透氣的相關產品上，但根據ePTFE的細微纖維孔徑大小及GAW324薄膜特性上，GAW324其水蒸氣穿透率可大於100 ，也就是薄膜的細微纖維孔徑仍大於氣相形態或水蒸氣的水分子小水滴，所以仍是阻擋不了環境中的濕氣穿透薄膜。因此研究實驗中以導入隔離水氣對策的測試Test-1與Test-2來以驗證說明，並另外以Test-3與Test-4的實驗量測，其取得沒有導入隔離水氣對策下其IP Camera造成起霧現象之時的溫度數據收集，且依據理想氣體狀態方程式之推導公式及參考利用ASHRAE(美國加熱冷凍空調工程師協會)使用手冊之相對濕度Wexler的經驗公式，推算出Test-3與Test-4所量測出的各Channel點溫度之時的相對濕度值，並以說明起霧時IP Camera內部的溫度分佈與相對濕度分佈的關係探討。希望以此說明IP Camera起霧現象問題的分析與實驗結果的推測探討，可做為相關產品在於應用透氣薄膜時發生起霧現象的問題解決參考。

This study describes the future application and development of IP camera and compares IP camera with conventional surveillance camera CCTV to explain characteristic differences between the two. In the study, IP camera was applied for analyzing the foggy phenomenon produced by breathable Gore-Tex film. The goal is to examine the appropriateness of currently available methods for preventing fogginess as well as to offer more effective strategies for resolving this phenomenon. Considering the manufacturing method of Gore-Tex breathable film and characteristics of ePTFE, a main ingredient of Gore-Tex breathable film, the breathable film of model number GAW324 was selected and applied in this study. This type of film is specifically used on microphone’s sound receiving holes to achieve the water resistant requirement. The airflow rate can be as much as 5 , while the water resistant level of the film can be as high as IP67. That is why this type of film is often used on products that need to be not only water resistant but also air permeable. Yet according to the diameter of the microfiber of ePTFE and characteristics of GAW324 film, GAW324’s water vapors permeability can be greater than 100 . In other words, the microfiber diameter of the film is still larger than either gas-phase or vapor-phase water molecules, and thus it cannot block environmental moisture from crossing the film. As a result, this study adopted the strategy of water vapor blocking (Test 1 and Test 2) for verification and explanation. In Test 3 and Test 4, experiments were conducted to collect temperature data at the occurrence of foggy phenomenon on IP camera when the water blocking strategy was not applied. By deriving the ideal gas equations as well as referring to the empirical equation of relative humidity from the hand book of American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE), relative humidity of the temperature of each channel point measured in Test 3 and Test 4 was computed. The authors also discussed the relationship between temperature distribution and relative humidity distribution inside the IP camera when fogginess happens. The ultimate objective is to resolve the foggy phenomenon observed on products using breathable film through analyzing the phenomenon and discussing the experimental results.