Re: Projector bulbs

[Marvin Jones <72657.3276@xxxxxxxxxxxxxx>]

>I've noticed that bulbs used for projection usually have a black coating on
>top.  What is the reason for this? Is it to lower the temperature directly
>above the bulb?  And would there be any danger in using an uncoated bulb in a
>projector?

I've always assumed that at least part of the reason is to keep unwanted light
from escaping through the vents on the top of the projector and illuminating the
room. There may be other reasons as well, and we'll probably hear them soon.


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