LED電子屏幕是否發出藍光？ Is blue light emitted by LED electronic display screens ?

(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.