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Sony Projector Gets Bright Images From Black Screen
da_foz writes "Sony has developed a new projector that can give a bright, unfaded picture without the need to eliminate ambient light. The secret is that they project onto a black screen instead of a white one. Their screen uses species filters so that white ambient light is absorbed, but the red, green, and blue light from the projector is reflected. Sony sees a possible use in home entertainment systems because of the ability to have a much bigger picture than conventional TVs as well as businesses adopting the projectors for presentations."
If it reflects _anything_, it isn't black.
It seems this is a surface that reflects only very selective frequencies, those used by their emitters. An interesting idea, but calling it black is deceptive.
I can see the use in business and public presentations. But other than the few home cinema zealots with giant rooms set up like theaters, how is this useful in the home? To me it seems like having a 24 inch penis. Sure, it'd be big and impressive, but not of much practical use to anyone.
...they could come up with a lamp that would actually last. I've gone through at least 6 InFocus projectors in the last 1.5 years due mainly to bulb failure.
...hey, what's that bright thing in the sky outside?
This technique sounds really cool though, perhaps I won't need to have all my windows boarded up anymore.
Absorbing everything except the wavelengths that the projector produces (and which the human visual system will still perceive as the full spectrum of colours) is *very* clever. If only the ambient light wasn't from massed banks of computer monitors...
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We'll finally be able to see the Gettysburg Address Power Point presentation the way Lincoln intended it to be viewed.
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I assume the three frequencies that are reflected are fairly well tuned. I wonder if this means I will be stuck purchasing a Sony projector to match these? I also wonder if Sony may be able to stop others from making matching projectors since they probably own some Patents around this technology?
It would seem that the ultimate version of this would use RGB lasers as the light source and notch filters on the screen. The narrowness of the notches would determine the depths of the black. The biggest trick would be in tuning the notch filters to reflect the off-axis, angled laser light.
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This isn't a new projector. It's a new type of screen that only reflects the projector light, absorbing the ambient light, so the image remains clear even in a bright room. It works with regular projectors. I'd at least expect the submitter to RTFA...
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The author of the article doesn't know what he's talking about!
In a bright room, the image on the screen is brighter
No, it isn't. It's clearer, it might _appear_ brighter because of that, but there's no way it could actually _be_ brighter. Unless the technology does something not described.
Since Thomas Edison introduced motion-picture projectors more than 100 years ago
I could have sworn the motion picture projector was introduced by Lumiere.
When your screen doesn't reflect so much of the ambient light anymore, you can use a projector that outputs less power. For one, this can lead to less hot projector lamps, thus a longer life for them.
It might also enable the use of lower-power technologies (LED-lasers anyone?), that might in turn make the projectors much cheaper.
Nice work by Sony
Now, is there a physicist in da house who knows how wide the reflection-band (in wavelength-terms) for R, G and B is?
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fourth sentence of the article:
In apparent defiance of color theory -- that dark surfaces absorb light and white surfaces reflect it -- Sony Corp. has unveiled a black screen that allows a regular digital projector to vividly display TV images and business presentations in a brightly lit room
jesus christ, is it too much to ask to have someone read the fscking thing first??
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I bought some high-end binoculars a while back. When you're looking through all the Nikons and Swarovskis and Leicas side by side, you start to realize when your eyes feel the little zing. It isn't pure resolution that does it, and your eyes compensate rapidly enough to changes in brightness (due to objective size or quality) that you don't often perceive differences except at dusk and dawn. (The only exceptions for me were old-style tank commander Zeiss binocs. Very bright.)
But when you hit a binoc that felt right for contrast, ahhh -- those were my handful of last choices. It's like seeing the world with the slanting light at around 6:30 on a summer night -- everything just pops out, so clear, and the slight 3-D exaggeration of the binocular view brings it out just that little bit more. The optics store people said that was a pretty common reaction -- a slight edge in contrast was a huge advantage.
Sounds like this screen has that going for it. Big selling point, next to potential competitors, if they can get it around the right price point.
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Sony engineers worked from the basic principle that projectors, like all TVs and monitors, form colors by blending three primary hues: red, green and blue. They came up with a filter that allows the screen to reflect only red, green and blue light. The other light in a room, such as white incandescent or fluorescent bulbs, isn't reflected.
Man I hate it when the newspapers print stupid things. Whaddaya wanna bet they are using something like polaroid or narrow bandpass quarter wave plate filters with a similarly filtered projector? What would be cool is a fluorescent screen and a projector that uses light (UV?) outside the visible spectrum. Then the screen really could be visibly black but it would still glow when stimulated by the projector.
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The article specifies that this is for use with digital projectors. I assume the reason for this is that single chip DLP projectors don't actually project white light onto the screen. The red, green and blue components of the image cycle so fast on the screen that your eye perceives this as different shades and combinations including white. All you need to do is have the screen absorb white light while reflecting red, green and blue and there you go. This is really an ingenious use of this effect, but I wonder if it is unusable with a 3 chip DLP projector that shows all components at the same time? You would at least need a more sophisticated screen in this situation.
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These crystals can be ground up and painted onto a screen or even the side of a building. Then all you need is an infrared laser to scan the the sreen and you have an extremely bright and cheap full color display.
I haven't heard much lately about their progress so I assume they are having some technical or financial delays.
If it reflects _anything_, it isn't black.
Of course it is. Every black object in the world reflects some light.
You are confusing black bodies, an abstract notion defined by physiscists which does not exist in the real, physical world, and the color black, which our eyes percieve just fine whether or not it is a shiny surface with a lot of reflection, or a matted surface with minimal (but still greater than zero) reflection. The black BMW I had the misfortune of following the other day positively glinted in the midday sun.
With light, black is defined as the abscence of color. With pigment, black is the presenece of all color (analogous to white light).
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Even with the best surround sound, there is still the issue of fan noise. If you enclose your projector in a cabinet, you shorten the bulb life due to heat. I've used various projectors over the years, and always end up back at my HD flat-tube system, because it has good contrast and is quiet. If they fix the contrast problem, I may give projectors another look, but the fan noise should become top priority.
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The common vernacular "bright" can either refer to luminance (close the shades, the light's too bright), or it can refer to color saturation (Can you tone down that bright green to a mere pastel?). A projector screen that reflects ambient light is going to reduce color saturation; and one that absorbs ambient light will increase color saturation, i.e. make it brighter.
Never mind about the projectors. I want to be able to use my laptop outdoors. There must be a reason I have wireless lan and a balcony. Since the root of all problems is that screens have luminosity instead of reflecting existing light selective reflection seems very interesting.
completely skirting around the fact that THERE IS NO SUCH THING AS WHITE LIGHT!
Sure there is, there's no such thing as white monochromatic light, but white light exists. The term "white" (whether it be talking about light, sound, etc.) simply means that the energy is distributed evenly across all frequencies (technically between 0Hz and infinity, but in practice we're talking about more or less evenly over a given band of frequencies). Since the energy is distributed over such a wide frequency band, the energy of the white light in the very fine bands used by projectors will be very small, so by absorbing everything else you will almost be eliminating the white light's energy.
Trueth be told, unless you're talking about monochromatic light, the simplistic names of colours only describe what we see - they can be generated by any number of combinations of different frequencies. I.e. monochromatic orange light has a wavelength of 590nm, but that would look the same to us as a mixture of red (650nm) and yellow (570nm) light (or any number of combinations of different wavelengths).
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True white light (like what you get from the sun) consists of an equal spread of energy across all frequencies. You can make light that _appears_ white (to our eyes) by mixing a small number of different colours (for example, red, green and blue). See my other post.
http://blog.nexusuk.org
No.
Red+Green+Blue light _looks_ white to us, because our eyes cannot distinguish it, as they have only 3 receptor types that are tuned to those wavelengths of light.
White light contains all frequencies of visible light. We can see all frequencies of visible light, it is simply that we cannot distinguish them from an appropriate combination of the two nearest frequencies our eyes are tuned to.
This screen filters out the frequencies other than narrow bands around those used by the projector, which are (approximately) the same frequencies that our eyes are tuned to. This means that something like 90% of all the other frequencies that are in the white ambient light are absorbed, while almost all of the light from the projector is reflected.
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As others have pointed out, a truly black screen wouldn't reflect the projector's light. And, conversely, a screen that is able to reflect the red, green, and blue light from the projector will reflect some of the ambient light, which contains some light at the projector's R, G, and B wavelengths. It's too bad the article has to describe it as "Gee whiz! it's technological magic!"...
What we need to know is: a) what percentage of white, ambient room light does the screen reflect? It's not zero, and the screen probably looks like a dark grey. b) When the projector is projecting "white" light, what fraction of that light is reflected? Not only is it less than 100%, it's probably less than a white screen would reflect.
Other things one would like to know are whether the filters that do this magic cause any visible graininess, and over what angle the reflected light is reflected.
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The technology here is in the screen, not the projector. In particular, the screen absorbs most light, with the exception of the primary bands illuminated by the projector's bulb.
Any projector with the same type of bulb---and in home theater nowadays, there are only two main types (Xenon and UHP), will work with this setup. And Sony could conceivably make a similar screen for the other bulb type too.
There have been so many dupe threads over at AVS Forum (by far the best place to go to discuss anything home theater) that it is getting a bit irritating.
Reading the article (although it is a little shy on detail) suggests it is bandpass filters in addition to what you suggest. I'm not sure why you think you need more than R, G, and B to produce all the colors present in RGB video. To reproduce the entire visible color gamut, you'd need more than RGB-- but RGB video has already reduced the color gamut significantly from what you can see. And, conveniently, consists of exactly three narrow wavelengths of light, and nothing else. Your suggestion that images require "many wavelengths of light" is completely incorrect. You'll have issues if your only source of ambient light is a bank of computer monitors, though, as they'll fall right into that nice RGB range.
I'm not sure they'd put too much dependence on angle, either-- most projectors these days are designed with an enormous optical offset (The popular Sanyo Z2 can be offset by 1/2 screen width and 1.5 screen height) and digital keystone correction (Allowing for projector placement even farther outside the offset range by correcting the shape of a picture projected at an angle). Lots of people use projectors but don't have a room situated so that the unit can hang conveniently from the ceiling dead center.
No, this will only work with a digital projector. The screen only reflects pure blue, pure green, and pure red. Any other color gets absorbed. A digital projector will work fine - any analog projector will look just like someone projected it on to a black screen, unless someone comes up with a film that only projects the same three wavelengths.
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It seems like a feasible variation, at least to me -- keep the mostly-black coating to absorb nuisance ambient light, but allow transmission at narrow RGB wavelengths. Then backlight it with an LED screen, with the diodes tuned to the three transmission frequency ranges.
Don't know whether it's technically possible, but if it is, I bet it's in the works already.
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This patent from Sony gives some detail. To view the images, you need a tiff-viewer plugin.
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For outdoor use on a laptop screen, you want a transflective display. I'm quite sure I saw a transmeta laptop with a transflective (rather than backlit) display at one point...
Ah, here it is.
Many DLP projectors, especially those targeted to the business sector, have a white section on their color wheel to increase brightness for slide presentations which tend to have a large amount of white. I imagine this screen would reduce the effectiveness of these projectors. Now the amount this reduction would be offset by the increased contrast of the screen, I wouldn't know.
While this screen sounds very cool, people with very bright projectors have been projecting on "black" surfaces, even black velvet, for a long time. It results in amazing colors and high apparent contrast _if_ you have an extremely bright lamp to overcome the absorption.
I, on the other hand, took the opposite approach-- a $50 screen made of plain 300 count white bedsheet (king size) stretched tight over a thin wood frame. Better than any $500 screen I've seen, but I'd love to see this new one in action.