首頁 Tech Solution OLED 華凌光電-解決方案 防護紫外線傷害而延長OLED壽命

華凌光電-解決方案 防護紫外線傷害而延長OLED壽命

紫外線(UV)光比可見光波長更短且能量更大(如圖1所示),眾所周知,如果暴露在高強度的紫外線環境中 , 紫外線會對人體造成傷害。 另外還有一些東西也會受到紫外線的傷害,比如OLED顯示器中的有機材料。

 

圖1 光譜分佈圖

[圖1 光譜分佈圖]

 

通常會使用紫外線指數(UV index)來定義紫外線的強度,它是衡量特定地點和時間紫外線輻射強度對人體所造成傷害的國際標準。如表1所示。

 

UV index Media graphic color Risk of harm from unprotected sun exposure, for the average adult Recommended protection
0 to 2 Green "Low" A UV index reading of 0 to 2 means low danger from the Sun's UV rays for the average person. Wear sunglasses on bright days. If you burn easily, cover up and use broad spectrum SPF 15+ sunscreen. Bright surfaces, sand, water, and snow, will increase UV exposure.
3 to 5 Yellow "Moderate" A UV index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure. Stay in shade near midday when the Sun is strongest. If outdoors, wear sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 15+ sunscreen every 1.5 hours, even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand, water, and snow, will increase UV exposure.
6 to 7 Orange "High" A UV index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Protection against skin and eye damage is needed. Reduce time in the sun between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 15+ sunscreen every 1.5 hours, even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand, water, and snow, will increase UV exposure.
8 to 10 Red "Very high" A UV index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Take extra precautions because unprotected skin and eyes will be damaged and can burn quickly. Minimize sun exposure between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 15+ sunscreen every 1.5 hours, even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand, water, and snow, will increase UV exposure.
11+ Violet "Extreme" A UV index reading of 11 or more means extreme risk of harm from unprotected sun exposure. Take all precautions because unprotected skin and eyes can burn in minutes. Try to avoid sun exposure between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 15+ sunscreen every 1.5 hours, even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand, water, and snow, will increase UV exposure.

[表1 紫外線指數(UV index)]

 

有機材料製成的發光層是OLED顯示器發光的關鍵,但是高強度的UV能量會破壞有機發光層的結構,在這種情況下會影響發光效率,OLED顯示器的亮度會下降。為了保護有機材料免受紫外線的傷害,必須盡量減少紫外線波長範圍的強度,同時保留可見光範圍(400nm~700nm)的強度,採用偏光片是非常有效的解決方案。如圖2所示。

 

圖2 偏光片之穿透光譜分佈

[圖2 偏光片之穿透光譜分佈]

 

為了證明偏光片對紫外線的防護能力,我們設計了一個實驗,使用偏光片覆蓋OLED面板的一半區域,另一半區域無任何覆蓋。 然後將OLED面板放入UV照射腔體,經過UV照射後測量OLED顯示屏兩個區域的亮度,即可得到OLED面板在UV曝光下的亮度衰減率數據。根據實驗結果,如圖3所示。藍線曲線是偏光片覆蓋的區域之OLED光亮度衰減曲線,在承受相當於1 UVI強度的能量照射450小時後,亮度衰減了0.76%;紅線曲線是沒有任何偏光片覆蓋的區域之OLED光亮度衰減曲線,在相同的UV照射時間下,亮度衰減了4.97%。此結果說明有偏光片保護時,可以延緩OLED面板在UV曝光下亮度衰減的效果。

 

圖3 有含(藍線)及不含(紅線)偏光片覆蓋之OLED光亮度衰減曲線

[圖3 有含(藍線)及不含(紅線)偏光片覆蓋之OLED光亮度衰減曲線]

 

綜上所述,OLED模組加上偏光片可有效抵抗紫外線的影響 , 建議有機會照射到陽光的產品應用都要加上偏光片保護OLED面板 , 一般手持式產品加上偏光片在戶外使用是沒有問題的 , 而戶外定點裝置則是建議除了偏光片外還要加上遮蔽物避免陽光長期直射以延長使用壽命。

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