LED與藍光 ( LED and blue light )

LED is the most recommended light source nowadays. Apart from light bulbs, it is also used in the background light of electronic display screens, such as your smartphone 1   and computer monitors/screens 1 , etc. As LED is not too hot and energy saving, it is greatly promoted and is used to replace other more traditional light sources, such as fluorescent tubes, curlicue compact fluorescent light bulbs, and incandescent light bulbs. However, it is exactly because LED lights produce a fair amount of light in the blue spectrum 4   (or called ‘blue light’), that they are so bright! There is no free lunch in this world; we may be paying a price 4  to use LED. According to a research paper called ‘The Effects of Blue Light On Ocular Health’   5 , written by Elaine Kitchel of the American Printing House for the Blind, the wavelength of blue light is ‘near UV’   5 :  http://www.tsbvi.edu/instructional-resources/62-family-engagement/3654-effects-of-blue-light

English translation 'What is LED? Its disadvantages and problems:  https://ledandbluelight.blogspot.com/2016/11/what-is-led-its-disadvantages-problems.html LED (Light emitting diode) 中文譯為發光二極管或 發光二極體 ，是現在最受推崇的光源，除照明用的燈泡， 也用於電子屏幕照明用，例如你的智能手機 1 、電腦顯示屏 /螢幕 1 。 由於不太熱、節省電力，所以 LED被大力推崇， 要取代其他舊式發光燈源，例如光管、慳電膽、鎢絲燈等。 但正因為 LED燈比起光管或慳電膽， 有相當多藍光 4  (light in the blue spectrum 4 , or called ‘blue light’)， 才那麼強光 6  ! 世上那有免費午餐 ? 我們可能要付上代價 4 了! 根據美國視障服務機構 American Printing House for the Blind 的 Elaine Kitchel 發表的研究文章‘The Effects of Blue Light On Ocular Health’ 5 ，藍光的波長是‘近乎紫外光’(near UV)的 5  ! http://www.tsbvi.edu/instructional-resources/62-family-engagement/3654-effects-of-blue-light 另一方面，根據哈佛大學 Harvard Health Publications 發表的研究文章 'Blue light has a dark side'，慳電膽及LED燈比傳統鎢絲燈泡更節能，但也製造更多藍光 4 ，參考： http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side 總括，不同研究或文章均指出  (見下面參考資料)，像短波長的LED這樣的新光源所引起的問題有如它聲稱想解決的問題那麼多 3 ，例如：光害 (blue hazard)  6

(English translation at the bottom.) 看看新款的巴士顯示屏白色變成藍色： 肉眼望是白色‘底色’，但從較側的角度拍攝， 原本白色的‘底色’也帶有紫藍色！原因何在？ 是否表示屏幕的光帶有藍光？ 那麼同類的電腦或電視屏幕呢？ 須知：藍光的‘波長’  (wavelength) 比較短、接近紫外線  (根據Elaine Kitchel 的文章 'Effects of blue light on ocular health')。 因此，長遠而言，藍光會對眼睛造成傷害， 尤其近距離及長時間觀看這些屏幕。 A display screen used on a new bus turns purplish blue when looking from the side.  The background should be white. Why does it look blue then?  Does the blue color come from the blue light emitted by the screen?  How about other similar screens, like computer monitor, ipad, and TV?  Please note that the wavelength of blue light is relatively short and near ultraviolet ray, according to Elaine Kitchel's article 'Effects of blue light on ocular health'.  So, in the long run, blue light is harmful to our eyes too,  especially looking at these screens at a near distance and for long duration.

'藍光有黑暗的一面' ( 'Blue light has a dark side' ) 哈佛大學醫學院  Harvard Health Publications 2012年發表的文章： 'Blue light has a dark side' 除了解釋藍光影響睡眠及引起健康問題外， 也指出 LED有最多藍光 (blue light)，其次是熒光燈(慳電膽)， 傳統鎢絲燈泡藍光比熒光燈 (慳電膽)為少...... 文章又指出： 燈泡裏面可製造  'coating' 令光 'warmer' ('暖些')以減少藍光。 所以建議大家買燈泡、光管等，要買  'warm white' (暖白光)， 不要買  'cool white' (冷白光)或 'cool daylight' (冷日光)! 因此，建議近距離用的燈，最好避免用 LED燈! 例如檯燈、工作燈、飯檯燈、牀頭燈。 其他文獻亦指出， LED 燈雖節能， 卻最影響眼睛、睡眠、城市光害、 在棄置時污染環境、影響植物生長等， 日後在這網誌慢慢解釋。 參考 'Blue light has a dark side'原文： http://www.health.harvard.edu/st…/blue-light-has-a-dark-side