P3D Re: Cooling fan protects projector, not slides

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Michael Kersenbrock asks on this:

>> The function of the fan is mainly to cool the projector, not the slides.  

>Is this just an attribute of the TDC projector or is cooling the slide just
>thought secondary?  I know my Compco Traid's fan does blow some air on the slide,
>and therefore seems like it should be cooling it, even if it isn't the primary
>purpose.

I think that cooling the slide is secondary.  Most of the airflow in the TDC
projector goes to the lenses, heat filters, polarizing filters.  Especially
the heat filters built up a tremendous amount of heat because that's
exactly their job.  But some air flow goes through the slide carrier too.

>Would the slide temperature rise at the same rate without the airflow? Would
>the eventual equilibrium point be at the same temperature?

Yes, that's correct.  However, temperature equilibrium is rarely reached
in the short time that slides are projected.  I think the main purpose of
the cooling fan is to lower the temperature of the projector parts that
are in constant exposure to the heat from the lamps.  

George Themelis


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