[visionegg] Re: DLP projectors and increased frame rate

For those who are interested, here's what I've found out so far:
apparently, most DLP projectors with a spinning color wheel have
segments of unequal size, meaning that the R, G, and B segments of
each frame are of different temporal lengths.  Many projectors also
have a white channel.  So I don't think that tripling the frame rate
of one of those projectors is an easy thing to do.  However, there is
a paper where an engineering group did something along those lines:

https://webmail.med.yale.edu/horde/util/go.php?url=http%3A%2F%2Fspiedl.aip.org%2Fgetabs%2Fservlet%2FGetabsServlet%3Fprog%3Dnormal%26id%3DOPEGAR000042000001000163000001%26idtype%3Dcvips%26gifs%3Dyes&Horde=924caf9de688f10c03a211826c5194d4

Basically, the projector has a photodiode on the other side of the
color wheel from the lamp, and it detects which segment of the wheel
is in place by the current through the diode.  So the authors built a
circuit to simulate a photodiode current so they could manipulate the
projector more easily.

For my purposes (high frame rates), I've found the Infocus makes some
projectors that can project at rates up to 130Hz, which isn't as fast
as I wanted, but it's still probably fast enough for my purposes.  The
only thing I'm a little concerned about is if the projector can sync
to an incoming signal at 130Hz, but actually downsamples and projects
at a slower rate.  I remember hearing once that some DLP projectors do
this (though they should be easily capable of projecting at obscenely
high rates).

I also looked into the DLP developer's kit.  They were very expensive,
and they are controlled with a special controller card that I would
guess is harder to program for than an OpenGL graphics card.  However,
I think one could get really high frames rates with one.


Luke



On 8/15/05, Andrew Straw <astraw@xxxxxxxxxxx> wrote:
> I recently came upon the idea of buying a DLP developer's kit, either
> from TI or a 3rd party. I haven't investigated any further, but it may
> give more flexibility than a commercial product.
> 
> I think we'd all be interested in anything you find out, Luke, so if you
> get a chance, please send us an email if you find any good sources of
> information.
> 
> Cheers!
> Andrew
> 
> Luke Sjulson wrote:
> > hello,
> >
> > There was a discussion in the archives of this mailing list saying
> > that someone had heard of someone removing the 3-color wheel from a
> > DLP projector, creating a white light projector with triple the frame
> > rate.  Does anyone on this list have direct experience with hacking
> > DLP projectors, or know of anyone who does?  I'm trying to find a DLP
> > projector where I can remove the 3-color wheel and encode three
> > subsequent frames into the R, G, and B channels, but I want to make
> > sure that I can find a projector where each frame is split into equal
> > thirds.
> >
> > Alternately, if someone knows of a 3-chip DLP projector running at
> > over 100Hz that doesn't cost $30,000, that would be great too...
> 
> 
> 
> >
> > Thanks in advance!
> >
> >
> > Luke
> >
> 
> 
> --
> Andrew D. Straw  Post-doctoral scholar
> ,-.              Dickinson Lab
> \_/              California Institute of Technology
> 8||}             Mailcode 138-78
> / \              Pasadena CA 91125, USA
> `-^
>                  email:  astraw@xxxxxxxxxxx
>                  office: +1 626 395 4396
> 
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-- 
Lucas L. Sjulson
Cornell/Rockefeller/Sloan-Kettering MD/PhD Program
Laboratory of Neural Systems (Miesenboeck Lab)
Yale University School of Medicine
295 Congress Avenue, Rm # 247
New Haven, CT 06519-1418
(203) 785-2311
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