台灣年齡結構自民國82年起邁入高齡化社會，65歲以上老人所占比例持續攀升，98年底已達10.6％，雖仍較已開發國家為低，如歐美及日本等，但較其他亞洲國家為高。在人口老齡化的趨勢下，如何提升銀髮族的生活品質已成為一項重要課題。目前的行動顯示技術已日趨成熟，銀髮族操作行動顯示器比起以前傳統電腦更為簡單以及靈活，行動電子產品，包括觸碰式平板電腦(如iPad、All-In-One PC等)，逐漸受到廣大的歡迎。本論文使用心理物理實驗方法來探討銀髮族使用行動顯示器(iPad 2)的視覺舒適度，並將心理物理實驗結果與年輕人的實驗結果比較不同之處。

為了探討年長者與年輕人使用行動顯示器閱讀文章的視覺舒適度，本論文以兩個心理物理學實驗來進行探討。總共有62位受測者參與實驗，其中36位為年長者，26位為年輕人。總共有444組文字-背景的配對比較。顯示尺寸大小包括iPad 2以及 iPod touch 4。實驗分為兩部分，實驗一為無彩色之背景與文字組合，實驗二為有彩色的背景搭配無彩色之文字。在iPad 2以及 iPod touch 4尺寸下進行實驗一，實驗結果顯示，越高的△L*，年長者有越高的視覺舒適度，但是對於年輕人而言，當△L*大於80後，視覺舒適度開始維持不變甚至下降。在實驗二時，於iPad 2尺寸下的實驗結果顯示，越高的△Eab*，年長者有越高的視覺舒適度；但是對於年輕人來說，在△Eab*大於60後，視覺舒適度開始維持不變或是下降。而在iPod touch 4尺寸下進行實驗二時，年輕人與年長者視覺舒適度差異較小。

Taiwan has become an aging society since 1993. The proportion of people over 65 years old continues to rise. It reached 10.6% at the end of 2009. Although the proportion of older people is lower than some developed countries such as the U.S, Europe, and Japan, it still is higher than that in the other Far East countries. With the trend of aging society, how to improve the life quality of older people has become an important issue. Because the mobile technology has gradually matured, using the mobile devices for older people is easier than the traditional computer. The mobile devices including touch-based tablet computers (such as the iPad, All-In-One PC, etc.) has been well received.

Two psychophysical experiments were conducted to investigate the effect of observer age on visual comfort for reading coloured document layout displayed on an iPad 2. Twenty-six young observers and thirty-six older observers participated in both experiments. During the experiments, each observer was presented with 444 pairs of document layouts on the full screen of an iPad 2 and then in the screen size of an iPod touch 4 also on the same iPad 2. The observer was asked to pick one of the two layouts, of which the observer felt more comfortable to read the text. Results of Experiment 1 show that for achromatic text-background combinations, the higher lightness difference between text and background, the higher visual comfort for older observers. For young observers, on the other hand, the visual comfort values for achromatic text-background combinations remain unchanged or even start to decline for CIE lightness difference over 80. The trend of visual comfort value for iPad 2-size and iPod touch 4-size is similar. Results for the iPad 2-size of Experiment 2 show that for document layouts containing achromatic text and coloured background, the higher CIELAB colour difference between text and background, the higher visual comfort for older observers. For young observers, however, the visual comfort values remain unchanged or even start to decline when CIELAB colour difference gets larger than 60. Results for the iPod touch 4-size of Experiment 2 show similar trends for young and older observers.

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