[PLUG] Urgent: Screen for Advanced Topics (2)

[Keith Lofstrom]

> On Wed, 15 Apr 2009 23:33:27 -0700
> Jeff Kirsher <jeffrey.t.kirsher at intel.com> dijo:
> 
> > > So ... how to deal with this for the "average" talk at future AT
> > > presentations?  I can project an 8 foot wide image on that orange
> > > wall, or I can bring my portable 5 foot wide screen and set it up
> > > on a table.  Which image would people rather see at Advanced Topics?
> 
> > Would it not be easier to simple hang a white sheet?  That way, you do
> > not have to bring a portable screen and you can cover more than a 8
> > foot wide area.  Just a thought.

On Thu, Apr 16, 2009 at 07:48:26AM -0700, John Jason Jordan wrote:
> A sheet will always be wavy because the material is not stiff enough.
> 
> Hauling around a screen is a PITA. I wonder if Roots would be willing
> to put up a white board on that wall. Are we the only group that uses
> the room? Could they get more business from group meetings if they
> adapted the room a bit?

A white painted area for projection would be good, above the "fingerprint
zone".  They  probably painted the wall orange because the white wall
looked messy, and orange doesn't show dirt very well.  Venues such as
McMenamins invest in real roll-up screens for a reason; it keeps the
projection surface out of harm's way during food fights or equivalent.  

While shopping for screens, I learned that there is a lot of engineering
that goes into a projection screen.  They are designed to reflect light
evenly over specific ranges of angles and not others.  Light from an
off axis open door won't shine into the audience.  Projection light is
not wasted on ceilings and walls.  On older screens, this is done with
tiny glass beads in a white paint matrix.  On newer screens, an
engineered plastic surface does the same thing.  This means that a
projector with limited lumen output (mine is 1100 lumens) can project
a visible image on a larger surface.  And that is why people spend
hundreds of dollars on a good Da-Lite screen.

The threads in a sheet don't do that, even if the sheet was stretched
in a frame to make it flat.  A wall painted with "screen paint" is
better, but not as good as a properly designed real screen.

A used projection screen might be OK, but buyers should be aware that
aging "paint and bead" surfaces turn yellow and lose their adhesion. 
They are almost impossible to clean - most cleaning products discolor
the paint.  And over the years, stuff gets thrown at them, so a lot
of the old ones have stains.  That is how Da-Lite stays in business.

All that to deliver photons to a few eyeballs.  In "The Wonderful
World of the Future" (tm), maybe we won't have screens.  Instead,
multibeam projection systems will send out small beams of photons
to converge on each of the pairs of retinas in the room, without
wasting light on all the other surfaces.  Of course, it might be
even cheaper to rewire audience brain neurons, so they are left with
the same experience as viewing a slide show or movie or whatever
("Would you like your movie memory to have popcorn in it, and do
you want to remember real buttery taste?  That will be $7 extra").  

To make this on topic, would somebody write a Linux app for this? :-)

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs