Re: [Phys-l] LED phosphorescence

[Spinozalens@aol.com]

In a message dated 6/25/2011 1:03:36 A.M. Eastern Daylight Time,  
jim.deane@gmail.com writes:

A  more cost effective method is to use UV or blue LEDs and
>  broaden  the light spectrum using phosphors.
>
> What I am pretty sure is  happening is that the phosphor needs  time to 
heat
> up before it  emits light over a broad spectrum, the purple tinge  
reflects
> the  fact that the LED's being used are emitting UV light. I can't  find
> anything in the literature on LED lighting that talks about  this, hence 
my  post.
> Bob Zannelli

I am curious,  when you cut power to the LED array, does the array
continue to glow at  all?  If so, what color?

It won't be a long-acting phosphor like  they use in commercial
glow-in-the-dark materials these days, but it may  have a residual
glow.

-- 





When the LED lights are shut off , they go dark instantly. If they have on  
recently, and have not had time to cool down they come to full brightness  
instantly. So it's definitely heat related. There is nothing available that  
explains this effect that I can find. But it has to be a temperature effect 
with  the phosphor material. LEDs switch at high speed , they are used in 
fiber optic  communication. ( Though LASERS are better.) 
 
 
Bob Zannelli