Slashdot Mirror
Matchbox Sized Color Projectors?
Justin Nolan sent in a very brief link about
ultra small projectors which says
"Upstream Engineering is willing to provide miniature color video projectors for use with portable video player, travel TV, laptops and handhelds next year. Upstream's patented technology, called Photon Vacuum, maximizes the amount of photons sent to the target from the light source in a minimum space and allows the creation of devices free of a variety of components currently used in projectors that unnecessarily waste energy. Photon Vacuum enables the smallest projector designs in the world, ultimately to a size of matchbox. The company says is going to push the power consumption of the whole device ultimately to below 4 watts while still gaining a travel-TV sized color projection" You can also read Upstream's website for almost as little information.
The projector:
l
http://www.upstream.fi/index.html
The Technology
http://www.upstream.fi/technology.htm
Upstream's unique and revolutionary technology, called Photon Vacuum, practically maximizes the amount of photons sent to the target from the light source in a minimum space. This is not an easy trick since the etendue law of light in physics requires more space for better efficiency. Our special technology enables us to get rid of a variety of components currently used in projectors that unnecessarily waste energy. The current table projectors extract typically only a few watts of light power out of 200W of input power.
Photon Vacuum enables the smallest projector designs in the world, ultimately to a size of matchbox. It is possible to push the power consumption of the whole device ultimately to below 4 watts while still gaining a travel-TV sized color projection. There are a myriad of possible applications for this technology.
First in the world, Upstream Engineering introduces a revolutionary optical technology that will enable video projection from matchbox-sized device running on batteries.
Our expertise covers all the necessary areas from micro-optics to low-power digital electronics. We design custom projectors based on our unique technology.
The new Swedish "OptiLight" projector for should drive prices down later in 2004. It's expected to retail for $500.
Optics.org had an article
this summer about a pair of other pocket projector projects. These includes using an array of lasers to limit scanning or a single higher powered light-source. If 'pocket' is the only thing that matters you might also look into a development of normal bar-code scanners.
Do you actually believe that you can project a reasonable image with _4 watts_ of power? You need energy to create photons. Even with zero heat loss, you can't get a luminous image out of 4 watts. This is vaporware at best.
Well, at 640x480 I'm not so sure. Seems way too lo-rez, especially for vaporware, no matter the price... (And reading the articles in their archive, I'm Swedish -- too, Mr. nickname-from-nastiest-'food'-in-Swedish-cuisine ;) -- they claimed "600x800" in October 2002, article in Swedish.)
Furthermore, their current data/spec. on rez and price are (still) their own "target values".
From what I gather, they do have some new kind of cooling system (patents pending), which they claim is good enough to make next-generation projectors completely fanless. Time will tell, of course.
668.5
In the shop I work in we demo projectors regularly. 1000 lumens can be seen adequately when projected through a sheet of perspex onto a blue wall in full indoor lighting. On a proper white screen with the lights dimmed 700 lumens should be fine. Even better for lumen-optimisation is using it to project onto a sheet of paper from behind - looks like a nice flatscreen TV, very portable and doesn't depend on light conditions nearly so much.
If I were buying a proper projector for home cinema I'd go for 1900+ but something cheap and portable to show up charts or a slideshow of my graphic work would work fine with 700.
They could be doing laser scanning, but I doubt it. I bet they're using LEDs as the light source. Possibly micro arrays for the actual image, but most likely still sticking with a small LED array that has the three colors, a special lensing system that focuses them through a monochrome LCD (cheap non-high temperature transmissive) and then another lens which then produces the output.
This would provide several advantages. First, it would be fairly efficient since 4W of LED power is still fairly efficient (though still 'hot' and not close at all to the ideal 100%). The cheap LCD display due to the lower heat. Small size, especially if high index refrective lenses are used.
Disadvantages are many. Traditional projectors use a bulb which, for all intents and purposes can be modelled as a point light source. Optics are easy, comparatively. For a LED array the optics would be...non trivial. I suppose they could be using single LEDs but even then the leds are seperated, which still makes the job difficult. Another is that the smaller the package, the smaller the optics. The smaller the optics the worse the image. There's a reason you'll never get 4 meter telescope pictures out of a 10cm telescope. The resolving power of the lenses is limited by their size. The LED element will be huge compared to the lens size, and the picture is simply going to be poor.
It'll happen, through this speculative idea or through another, but real multimedia projectors for a given size projection have to be at least as large as the lens has to be for the quality you want. The only thing they might be able to make gains on without ruining the quality are lamp efficiency, lower heat output (these are coupled), and the design of the lens systems currently needed to throw a decent image across a room.
-Adam