Good point. Why then do CRT projectors produce better blacks ? If the screen is white, the screen is white.
As I understand it, the reason CRT systems have the blackest blacks is because they are literally colored light tubes. You have one tube for each color, red, blue and green; white is a combination of all the tubes and black is when none are lighted (or "excited"). Each tube generates it's color by electrons striking a phosphor coating at the end of a vacuum tube (cathode ray tube).
DLP and LCD TV's or PJ's work in a totally different way. A DLP reflects white light that passes through a filter wheel with numerous colored filters in it and thus is being illuminated all the time so even totally black scenes get some light, but generally they give darker blacks than LCD systems do since LCD's actually block portions of light from coming through the screen (the same way your computers LCD monitor does) so to produce black they try to block all the light coming from behind the screen, but there isn't 100% blockage. That explanation was probably as clear as mud... to get a better understanding of how each of these systems work, hit the internet and I'm sure you can find some illustrations that are much clearer than my text.
Anybody ever tried a black screen?
A member of another forum actually did this, and it worked after a fashion, but you need a REALLY
bright PJ along with a small screen (by projection standards) for it to work. In his testing he had to get the PJ so close to the black screen that he couldn't focus the image.
Also, I just read about a company (Vutec Silverstar) that uses crushed glass in their screen make-up. Sounds interesting and raises the question for DIYers. Anybody tried crushing glass into the mix? You could probably use a fabric sack and sledgehammer and a sacrificial Cuisinart to crush glass. Come to think of it, isn't sand crushed glass? Anybody tried sand in the mix? I'm tempted to try sand.
I actually will be ordering some microscopic glass flakes to try out in a screen mix. My main concern is that they will have a prismatic effect similar to mica flakes. We'll see. :nerd:
try to make your own flakes by breaking or crushing regular glass yourself! This is VERY
dangerous and you have no control over the size of particles produced. Besides the threat of being cut, you could also create glass powder so fine it goes air-borne and you, or others in the area, could breath that into your lungs - not good!
Common sand is too impure and/or fractured to be as reflective as a screen ingredient needs to be. Also, the size of the sand grains are too large. Some years ago I needed to build some ramps so my grandmother could use her wheelchair to get to street level and we could take her out to eat, medical appointments, etc. I learned that the way you increase traction on a painted wooden ramp is to paint it and then sprinkle dry sand on the wet paint! It worked like a charm!