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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68652

    Title: LED交通標誌之最適輝度與對比度研究;The Study of Comfortable Luminance Contrast of LED Traffic Signs
    Authors: 范成儀;Fang,Cheng-yi
    Contributors: 照明與顯示科技研究所
    Keywords: LED交通標誌;眩光;視覺舒適度;判別度;LED traffic signs;Glare;Visual comfort;Legibility
    Date: 2015-08-31
    Issue Date: 2015-09-23 13:57:53 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 交通標誌是人們生活中不可或缺的一部分,而現今LED 的普及化,以及傳統標誌在雨天或大霧易有視線不良的情形發生,使得人們嘗試將LED應用於交通標誌上。因LED 本身具有發光面積小及光源指向性強等特點,使得LED 交通標誌易有眩光的情形發生,故本研究設計執行LED 交通標誌相關的人因實驗,探討LED 交通標誌的判別度與舒適度。

    LED 交通標誌人因實驗以對比度及綠色背景輝度為實驗因子,其中對比度為綠色背景輝度對白色字體輝度之比。實驗設計的輝度範圍參考經濟部能源局與北美照明協會的規範,定於20-500 nit;對比度則是參考顯示器研究的文獻,定為1:2 至1:11 間,並以標誌判別度與顯示舒適度問卷,得到受試者的主觀評量。

    將實驗數據匯入統計軟體進行分析,結果顯示,LED 標誌的綠色背景輝度沒有達顯著水準,而對比度則是達顯著水準。事後比較結果顯示對比度範圍介於1:7 至1:9 是被受試者認為最清楚與舒適的範圍,低於1:5則是相對視覺感受較差的。最後以實驗結果分別建立判別度與舒適度相對於兩個實驗因子的操作模型,提供未來架設LED 交通標誌的參考。

    關鍵詞:LED 交通標誌、眩光、視覺舒適度、判別度;Traffic signs are an indispensable part of our daily lives. However, the traditional traffic signs with retroreflective sheets and external lighting are
    almost invisible in severe weather such as heavy rains or fogs. With the popularity of LED lighting and display applications, people start to apply LEDs in traffic signs. Due to the characteristics of small light-emitting area and high directivity, LEDs are considered more probable to induce glare that disturbs human’s visual sensation. To investigate the legibility and visual comfort of LED traffic signs, an ergonomic experiment is designed and performed.

    Two factors are used in the experiments: the uminance contrast and the luminance of green background. The contrast is defined as the ratio of green-background luminance to white-text luminance. The design criterion for the luminance takes the suggestions from the Bureau of Energy, Ministry of Economic Affairs and IESNA (Illuminating Engineering Society of North America), and is set in the range of 20-500 nit. The contrast is set at 1:2 to 1:11,taken and slightly extended from the comfort region in VDT (visual display terminal) studies. Subjective ratings on legibility and visual comfort are
    obtained by questionnaires.

    The results show that the luminance contrast is a significant factor for both the legibility and visual comfort, while the green-background luminance is not.
    Post hoc comparisons show that the contrast from 1:7 to 1:9 is preferable when considering the legibility and visual comfort at the same time. The contrast less
    than 1:5 induces relatively poor visual experiences. Finally, the experimental data are utilized to construct mathematical models of legibility and visual comfort as functions of contrast and green-background luminance. Operating suggestions for LED traffic signs are drawn from the models to provide satisfactory legibility and visual comfort.Keywords: LED traffic signs, Glare, Visual comfort, Legibility
    Appears in Collections:[照明與顯示科技研究所 ] 博碩士論文

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