What's the Holdup With 3-D Monitors?
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From: whit3rd on 13 Jun 2010 21:07 On Jun 11, 3:57 pm, Bob Myers <nospample...(a)address.invalid> wrote: > On 6/10/2010 9:23 AM, Bret Cahill wrote: > > > Stereo vision should be easy with LCD monitors. Just polarize every > > other pixel one way and the remaining half 90 degrees. No one seems to have pointed out, that that is VERY HARD. LCD monitors depend on a polarizer, and those are mass-produced in UNIFORM SHEETS not in the mosaic as described above. It takes two, one between the backlight and liquid crystal panel, and one between the panel and the viewer. > And that's exactly how some current "3D" (stereoscopic) monitors work; > a patterned polarizer (generally, patterned such that alternating rows of > pixels are used for the L- and R-eye images) on the LCD, plus passive > glasses with matching polarization for each eye. I've heard of this done with multiple projectors, onto a single screen; that's actually easy to do. The left and right images, of course, aren't formed in the same place, just viewed in the same apparent position. > The other major type currently in use is the "shutter glasses" type, in > which the LCD is operated at twice the normal frame rate and the > stereo image pair is presented in field-sequential fashion, with LCD > "shutters" in the glasses synced with this presentation so as to prevent > each eye from seeing the other eye's image. My SGI Indy has a shutter-glasses video output, but it wasn't for LCD imaging because few LCD displays can update fast enough: it was for CRT systems (at 60 Hz, each eye sees 30 flashes per minute; that's not too bad, motion pictures were flickery at 24 Hz and are commonly flashed at 48 Hz with few complaints). The shutter glasses were LCD items, but the lit screens were CRT, I believe.
From: Jasen Betts on 14 Jun 2010 06:34 On 2010-06-14, whit3rd <whit3rd(a)gmail.com> wrote: > On Jun 11, 3:57 pm, Bob Myers <nospample...(a)address.invalid> wrote: >> On 6/10/2010 9:23 AM, Bret Cahill wrote: >> >> > Stereo vision should be easy with LCD monitors. Just polarize every >> > other pixel one way and the remaining half 90 degrees. > > No one seems to have pointed out, that that is VERY HARD. > LCD monitors depend on a polarizer, and those are mass-produced > in UNIFORM SHEETS not in the mosaic as described above. > It takes two, one between the backlight and liquid crystal panel, > and one between the panel and the viewer. all you need to do is add a mosaic of left-hand and right-hand optical isomers over the top of the front polarizer, enough for 45 degrees each way, this means the front polariser needs to be close to the pixel element to avoid parallax errors. stack-up something like this backlight back polarizer substrate (thick plastic or glass) colour filter wiring, TFT etc liquid crystal "backplane" front polarizer twister/repolarizer mosaic front cover (thick plastic or glass) --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Bob Myers on 14 Jun 2010 13:41 On 6/13/2010 7:07 PM, whit3rd wrote: > On Jun 11, 3:57 pm, Bob Myers<nospample...(a)address.invalid> wrote: > >> On 6/10/2010 9:23 AM, Bret Cahill wrote: >> >> >>> Stereo vision should be easy with LCD monitors. Just polarize every >>> other pixel one way and the remaining half 90 degrees. >>> > No one seems to have pointed out, that that is VERY HARD. > LCD monitors depend on a polarizer, and those are mass-produced > in UNIFORM SHEETS not in the mosaic as described above. > It takes two, one between the backlight and liquid crystal panel, > and one between the panel and the viewer. > Actually, it's not that hard. There are many 3D monitors being sold today which use exactly this sort of patterned polarizer. (Not many LCD panels, if any, are actually sold that way by their manufacturer, however - very often, the original polarizer is removed by a third party and replaced with a new patterned polarizer film to convert the panel for "3D" use.) >> The other major type currently in use is the "shutter glasses" type, in >> which the LCD is operated at twice the normal frame rate and the >> stereo image pair is presented in field-sequential fashion, with LCD >> "shutters" in the glasses synced with this presentation so as to prevent >> each eye from seeing the other eye's image. >> > My SGI Indy has a shutter-glasses video output, but it wasn't for > LCD imaging because few LCD displays can update fast enough: it was > for CRT systems (at 60 Hz, each eye sees 30 flashes per minute; that's > not too bad, motion pictures were flickery at 24 Hz and are commonly > flashed at 48 Hz with few complaints). The shutter glasses > were LCD items, but the lit screens were CRT, I believe. > LCD-based (meaning LCD as the display device) shutter-glasses 3D is also now on the market. It's much more common in LCD TVs than monitors at present, due to the difficulty of driving smaller high-resolution LCDs at the requisite pixel rates, but it IS starting to come to the monitor market as well. Bob M.
From: whit3rd on 14 Jun 2010 13:59 On Jun 14, 3:34 am, Jasen Betts <ja...(a)xnet.co.nz> wrote: > On 2010-06-14, whit3rd <whit...(a)gmail.com> wrote: > > > On Jun 11, 3:57 pm, Bob Myers <nospample...(a)address.invalid> wrote: > >> On 6/10/2010 9:23 AM, Bret Cahill wrote: > > >> > Stereo vision should be easy with LCD monitors. Just polarize every > >> > other pixel one way and the remaining half 90 degrees. > > > No one seems to have pointed out, that that is VERY HARD. > > LCD monitors depend on a polarizer, and those are mass-produced > > in UNIFORM SHEETS not in the mosaic as described above. > > It takes two, one between the backlight and liquid crystal panel, > > and one between the panel and the viewer. > > all you need to do is add a mosaic of left-hand and right-hand optical isomers > over the top of the front polarizer, enough for 45 degrees each way, > > this means the front polariser needs to be close to the pixel element > to avoid parallax errors. > > stack-up something like this > > backlight > > back polarizer > > substrate (thick plastic or glass) > > colour filter > > wiring, TFT etc > > liquid crystal > > "backplane" > > front polarizer > > twister/repolarizer mosaic and the mosaic has to be aligned to subpixel resolution across the whole surface of the display? Sounds hard to me. Do they print the mosaic with an inkjet of some sort? How do they get uniform density and achieve flatness?
From: Bob Myers on 14 Jun 2010 15:18
On 6/14/2010 11:59 AM, whit3rd wrote: > >> "backplane" >> >> front polarizer >> >> twister/repolarizer mosaic >> > and the mosaic has to be aligned to subpixel resolution across the > whole surface > of the display? Sounds hard to me. Do they print the mosaic with > an inkjet of some > sort? How do they get uniform density and achieve flatness? > Actually, the stack as given above is not quite right. The original "front polarizer" is removed before the patterned polarizer is applied (if it weren't, it would just be costing you more light). LCD polarizers are applied as adhesive films, and you're right, the patterned version used for "3D" monitors do have to be aligned to better than subpixel resolution - say, on the order of 0.01-0.02 mm. But with current processing equipment, that's not all THAT difficult. Bob M. |