Half a croissant, on a plate, with a sign in front of it saying '50c'
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Make your screen unreadable by....them.
  (+10, -2)(+10, -2)
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We've all been in situations where we'd rather somebody else wasn't looking over our shoulder at our computer screen. Maybe you're drafting MaxCo's latest patent while on a plane, or composing a threatening anonymous email whilst sitting in a crowded café.

Fortunately, MaxCo has the solution with its revolutionary new ScreenShades. Simply affix the Bluetooth transponder to the corner of your screen using the suction pad provided, install the ScreenShade software, and don the stylish ScreenShade glasses.

The screen-mounted transponder detects every refresh of the screen, sending a signal to the glasses. The ScreenShade glasses are a pair of rapid-response LCD shutters which, in response to the signal from the transponder, open to let you see only every third refresh of the screen. Meanwhile, the ScreenShade software displays noise (created from a scrambled, rotated and flipped version of the screen image) on your screen for the other two out of every three refreshes.

As a result, bystanders see nothing but a scrambled mess. You, on the other hand, see a perfect screen image, slightly dimmer and with a lower refresh-rate than normal, but otherwise quite acceptable.

MaxwellBuchanan, Dec 28 2008

Laptop/Notebook Video Glasses http://www.bitssite...sses/accessory.html
I wonder why these video glasses, or something like them, wouldn't work or could not be adapted to work the very way this idea describes. It's not "bluetooth", but it would be entirely private. [jurist, Dec 30 2008]


       "Them" are'nt going to like this. (+)   

       "with a lower refresh-rate than normal"   

       <Forgets to turn ScreenShades off> Walks into fast moving wall </fttsso> (+)
MadnessInMyMethod, Dec 28 2008

       "Them" may have high-speed cameras.   

       Lack of persistence of vision might make this unusable, also.   

       Good idea, though. I'm sure its workable somehow.
Spacecoyote, Dec 29 2008

       Them may indeed have cameras (in fact, any digital camera would do, provided you took several shots of the screen with an exposure of 1/100th of a second or less). However, it would prevent casual over-the-shoulder spying.   

       As for persistence of vision - yes, the screen would look a bit jerky, like an old movie. I don't know the refresh rate of modern screens, but I'm guessing it's 100Hz, in which case you'd see it at 33Hz - fairly watchable as a movie, and certainly adequate for writing and so on.
MaxwellBuchanan, Dec 29 2008

       Wouldn't it be simpler to just turn off your screen and have everything go to the glasses? You can do this with projectors or external screens.
energy guy, Dec 29 2008

       Simpler....exactly. That's the problem.
MaxwellBuchanan, Dec 29 2008

       I did a quick search to find out what a refresh rate is. I did this because I didn't believe it would work and I still don't. I'll grant you that my actual knowledge of these things is minimal at best, BUT...   

       I gather that it would be normal for my screen to have a refresh rate of about 30 times per second.   

       So the phrase: \\The screen-mounted transponder detects every refresh of the screen, sending a signal to the glasses.\\ sounds to good to be possible. The glasses would also have to react in time.   

       Am I right in understanding that you assume the screen changes all the individual pixels 30 times a second? In the case of the halfbakery for example I would think it much more effective to only change those bits that actually change.   

       I don't really understand what pixel is but I gather that my screen is made up of thousands of little lights that light up to give me a sense of a picture. Is it really true they ALL are refreshed at EXACTLY the same time 30 times per seond? Or does it work in waves? Why would the red "main index" sign at the bottom of the screen need to be refreshed all the time?   

       Sorry for my ignorance but I just don't believe this would work. Could someone with actual knowledge explain it to me like I am a four year old?
zeno, Dec 29 2008

       Well, the basic principal would work for CRT monitors. I know because I've used a 3D graphics system which had LCD glasses: the screen displays left and right images on alternate refreshes, and the glasses synch with that to give the impression of a stable 3D image. (That's every 2 frames instead of every 3, but we're in the right ballpark).   

       As far as I know, the whole screen is refreshed every time, not just the pixels that change. So, this should work.
MaxwellBuchanan, Dec 29 2008

       \\So, this should work.\\ Well if you say so, bun well earned.
zeno, Dec 29 2008

       Most software tries to limit updating as close as it can to the bits that actually change, approximating to save time. However, this is only on the video card side of things; the monitor doesn't know or care what bits actually change, it just refreshes everything, usually 60 times a second. Many monitors can handle speeds of 120hz but most LCDs can't.
Spacecoyote, Dec 29 2008

       Hmm - so, if the standard refresh is 60Hz and you saw every third frame, you'd be watching at 20Hz which might be a tad flickery (though less so for relatively static images such as text). At a pinch, you could probably use every second frame instead (giving the non-ScreenShade wearing overlooker an equal mix of noise and image), giving you a 30Hz image, which would probably be adequately sufficient enough.
MaxwellBuchanan, Dec 30 2008

       The glasses [jurist] linked to would be great, except that the resolution is far too low.
Spacecoyote, Dec 30 2008

are you able to read this?
xandram, Dec 30 2008

       [xandram] I am indeed, and thank you.   

       [jurist] et al - yes, "Glasstron"-type goggles are a good solution (and higher-res versions exist), but they prevent you from seeing what's around you (I think; perhaps semi- see-through versions are available), and have fixed resolution; ScreenShades would be considerably simpler, could be bluetoothed and cordless, exploit the full resolution (though not refresh rate) of any monitor, and let you see what's around you (albeit in a rather flickery way, not unlike Xenzag's 23.976 fps Glasses, q.v.).
MaxwellBuchanan, Dec 30 2008


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