This is an expansion of the final annotation in a thread that’s gone cold. I was curious to see what the reaction would be so I moved it here.

Disclaimer: I don’t actually know what the hell I’m talking about, except on a really speculative level. Any assistance is appreciated.

A diffraction grating is placed over the TV screen. Two different streams of broadcast are simultaneously presented on the screen (I don’t know how this can be done – some kind of compression?). Two viewers sit in front of the set at angles such that each sees only a discrete “packet” of broadcasting, that “packet” being directed according to the diffraction grating. A computer program assigns seating values consistent with directional values based on the grating (probably not that difficult for someone else to figure out) such that a viewer could not change his angle with respect to the set and still see his particular broadcast.

Subtitled audio transcription of discrete broadcasts is suggested.
-- snarfyguy, Feb 25 2003

You could have two panels of headphone sockets, one for each side.

I also think it would be a wise idea to control the grating via remote control, and have the panel turn so that if you decide to get up and move to another position, you can bring your screen with you.
-- monkeyseemonkeydo, Feb 26 2003


snarfy: I'm not quite sure where you're coming from on this one. A diffraction grating will cut down the light coming from the television. It won't do any mysterious redirection of the rays. Interference patterns won't occur as the light from a TV is not coherent.

You could have a collimator that wiggled left and right as the tv showed alternate frames...

You could use a lens to direct alternate pixels in different directions (baked)...
[later: nice link, budda_pest]

You could use LCD 'shutter' glasses to block alternate frames from each of the viewers (technology baked for stereo computer displays)...

...but I'm still not sure where you're going with the diffraction grating...
-- st3f, Feb 26 2003


That's probably due to a faulty understanding, on my part, of what a diffraction grating does. I thought it redirected light depending on angles of prisms (or something), so that you could send part of a light source in one direction and another part in another direction.

I was thinking of those novelties that show a picture that appears to move as you change your viewing angle. So you see a winking eye, but what's really there is an open eye and a closed eye, you just can't see them both at the same time. This is like that.

All I could find from Google was sites showing lots of scary-looking equations.
-- snarfyguy, Feb 26 2003


// lots of scary-looking equations //

Ahh, [snarfy] is an Algebraphobe ...... hee, hee, come on in little boy, I have a blackboard to show you ....

It could be done with a high frame rate screen and then have the viewers wear LCD spectacles which locked to alternate frames, maybe via an IR sync pulse. But it's a lot of trouble to go to; if the viewers have to wear specs, maybe 2 pairs of VR goggles are the thing.

Imagine the problems, though. You're watching a creepy movie and the Evil Monster is creeping up on the Dumb Teenagers, when your partner bursts out laughing because they're watching Blackadder on the other channel.
-- 8th of 7, Feb 27 2003


It would be really neat to go through an incredibly laborious process to bake this only for viewers to wind up using it to watch the same show anyway.
-- snarfyguy, Feb 27 2003


Buy another TV for goodness sake ! You can get a small 14" one for around $100.
-- riskyrisk, Oct 23 2003


I knew history would vindicate me.
-- snarfyguy, Oct 23 2003


Some of the Sony WEGAs have a picture-in-picture mode where the two pictures are equal size. One model even has a separate output to a set of wireless headphones, so both programs can be heard (one normally, one over the headphones).
-- krelnik, Oct 23 2003



random, halfbakery