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Technical Limitations to Wearable Eyeglass Monitors?
fprintf asks: "What is the technical limitation that is holding up wearable eyeglass monitors? It would seem to me that we have had miniature color viewfinders on Camcorders for quite some time, and with LCDs getting ever cheaper, what am I missing? I know there is quite a bit of interest in head and finger mounted pointing devices, but to me getting rid of that big monitor and strapping on a headset w/ the possible 3D implications would be wonderful. How about a GUI on an OS that supports Width and Height, but also depth?" It would be interesting to know how far wearable display technology has progressed in the past couple of years. Replacing the traditional goggles with (something closer to) a pair of eyeglasses will be a pleasant milestone for those Wearable Computing community.
Long version is that there are a few problems (mostly solvable):
You're projecting the image through a very small aperture. This causes any ray passing through the aperture to "fuzz out" over a certain angular range (as determiend by the aperture size and the wavelength of the light used). The limit is still a few thousand pixels wide for a reasonable monitor size and distance, but it's still a limit.
One of the main problems with LCD manufacture is that it takes a very clean environment. The finer the resolution of the LCD, the cleaner a clean room you need, because smaller grains of dust will still interfere with manufacture. If you want to put a tiny 1280x1024 LCD into a pair of glasses, that LCD will be many times more expensive than a screen-sized 1280x1024 LCD. This is one of the reasons why glasses-based displays have poor resolution (coarser resolution means cheaper screens).
This applies to most types of flat-panel display, not just LCDs.
Head-mounted displays aren't horrible ergonomically, but they aren't wonderful either. In their current incarnation, they're clumsier to use than a stationary monitor, and they're harder to do work on due to the lower resolution. There really isn't much of a reason (at present) to use a wearable display instead of an ordinary flat-panel display with your notebook or desktop.
The proponents of wearable computing argue that wearable computers (with displays) will be a new computing niche, but there doesn't seem to be enough demand (yet) to drive the prices down. This too is probably a convenience issue (would you really *want* to try to answer email while jogging, or in the press of rush-hour passengers while standing in a bus or train? If you're sitting down, you can use your laptop or palmtop.).
I'll be the first to cheer when affordable, high-resolution wearable displays reach the market, but they'll have to fight pricier technology and mediocre demand to do it.
Secondly, it's well known that if you don't have the two displays accurately aligned with your eyes, this can cause eye strain and headaches (this is why an optician needs to measure the distance between your eyes).
Finally, your eyes are most comfortable focussing at their "far point" - which should be at "infinity" - for most people, 5m or so is fine. Building the optics to project the lcd image so that it appears to fill your field of view, and come from a distance of 5m is probably not too easy (haven't really thought about it too much though). Again, any optics is going to add weight.