Active shutter 3D system
More actions
An active shutter 3D system is a method of showing stereoscopic 3D images in which a display presents left-eye and right-eye images one after the other, and the viewer wears glasses that block each eye in turn in step with the display, so that each eye sees only the images intended for it. The glasses are known as active shutter glasses, liquid crystal shutter (LCS) glasses, or simply shutter glasses; they usually contain two liquid crystal cells, one in front of each eye, and receive a timing signal from the display.[1] The display method itself is called time-sequential or time-multiplexed stereo, and is also described as frame-sequential stereo.[1][2]
The approach goes back to Laurens Hammond's mechanical Teleview viewers of 1922.[3] Liquid crystal shutter glasses were later used for stereo viewing on graphics workstations and in projection virtual reality systems, including the first CAVE,[2] and their largest consumer release came in early 2010 with the launch of 3D HDTVs.[1] Television makers dropped 3D in 2016 and 2017, and NVIDIA ended support for its 3D Vision shutter-glasses system in 2019, saying that the industry and its users had moved to newer immersive technologies such as virtual reality.[4][5]
How it works
A time-sequential stereoscopic display shows discrete left and right images in alternating sequence, often at 100, 120 or 144 images per second. The shutter glasses blank the left and right eyes alternately in the same sequence, so that the left eye sees only the left-perspective images and the right eye only the right-perspective images.[1] Because each eye is shut for part of every cycle, each eye receives half of the display's image rate: at 120 Hz, for example, a typical single-viewer system shows 60 images per eye per second.[6]
Andrew Woods of Curtin University lists four ways in which crosstalk between the two views arises in systems that use liquid crystal shutter glasses: the optical performance of the cells (their transmission in the "opaque" state, rise time, fall time and transmission in the "clear" state), the timing of the glasses relative to the display, the viewing angle through the cells (performance usually falls off away from perpendicular), and the temporal behavior of the display itself.[7]
Synchronization
The glasses need a timing signal from the display. Most wireless shutter glasses use an infrared protocol similar to those of television remote controls; some use a radio protocol such as Bluetooth or ZigBee, and the DLP Link protocol sends pulses of visible light in the projected image itself.[1] In a 2012 study, Woods and Jesse Helliwell characterized eleven different 3D sync protocols used by glasses and emitters from StereoGraphics, ELSA/H3D, NuVision, NVIDIA, Panasonic, Samsung, Sony, Sharp, Xpand and a Viewsonic DLP Link model. They attributed the lack of cross-compatibility mainly to differences between these protocols and noted that the incompatibility was "there by design": a pair of 2010 Panasonic glasses, for example, could not be used with a 2010 Samsung 3D HDTV.[1]
Shutter timing also differs between systems. Some glasses use a 50% duty cycle, with each eye open for half the cycle. Others use a narrow duty cycle, for example each eye open for 20% of the cycle followed by a 30% period with both shutters closed; some 3D LCDs need this reduced duty cycle to work correctly.[1]
History
Mechanical shutters
In 1922 the Teleview Corporation screened the science fiction feature Radio Mania with a stereoscopic process invented by Laurens Hammond, later known for the Hammond organ. A single film carried alternating left-eye and right-eye frames. Instead of wearing glasses, audience members watched through individual viewing devices whose spinning shutters were synchronized with the projector, blocking the right eye when the left-eye image was on screen and vice versa. The film played for a month at a New York theater that had spent US$30,000 to install the system; according to Invention & Technology, the need for precision machinery at every seat made it too expensive for wider adoption.[3] Woods and Helliwell date the use of active shutter viewing devices with time-sequential stereoscopic displays back to Teleview in 1922.[1]
Liquid crystal shutters and flicker-free stereo
In a patent filed in January 1983 and granted in June 1985, Lenny Lipton, Michael R. Starks, James D. Stewart and Lawrence D. Meyer of StereoGraphics Corporation described a "flickerless" stereoscopic television system that doubled the vertical field rate to 120 Hz while keeping standard bandwidth and horizontal frequency; viewers wore electro-optical occluding spectacles synchronized to the doubled field rate. The patent describes the earlier sequential approach, "sometimes called the eclipse or occlusion system", as giving each eye only half the usual field rate, which "results in intolerable flicker".[8]
StereoGraphics' CrystalEyes were, according to Woods and Helliwell, the first commercially available wireless active shutter glasses. They used liquid crystal shutters, ran on batteries and were synchronized by an infrared link.[1] In a 2007 interview with Physics World, Lenny Lipton, who founded StereoGraphics in 1980, described CrystalEyes as "the first practical electronic stereoscopic product for computer graphics and video".[9] Graphics workstation makers Evans & Sutherland and Silicon Graphics both used StereoGraphics eyewear.[10] A StereoGraphics patent filed in 1994 describes what CrystalEyes and similar products from IMAX, Tektronix and others had in common: liquid crystal shutters driven by on-board circuits and batteries, and an infrared sensor that receives field-rate synchronization from the video source.[11]
Game consoles and PCs
Nintendo released the Famicom 3D System, a pair of LCD shutter glasses with an interface box, for the Family Computer in Japan in October 1987. Sega released its own LCD shutter glasses for the Japanese Mark III console in 1988 and later that year for the Sega Master System, with games such as Space Harrier 3D.[12]
On the PC, the graphics board maker ELSA, with its 3D Revelator glasses, and NVIDIA led what Jon Peddie calls the second wave of PC stereo 3D in 1999. NVIDIA's stereo driver had trouble with post-processing effects such as bloom, HDR and blur, and the CRT monitors that the method needed were being replaced by LCD panels.[10] Regular LCDs are hold-type displays that output light for the whole frame period, and Woods wrote in 2010 that until recently it had not been possible to use time-sequential 3D with them, mostly because of their image update method; newer products made it work by changing the update method or by using black frame insertion, higher frame rates or a modulated backlight.[7]
NVIDIA's 3D Vision launched at CES in 2009.[5] The kit combined wireless rechargeable shutter glasses with an infrared emitter and required a 120 Hz monitor.[1][13] NVIDIA announced 3D Vision 2 glasses on 14 October 2011 with lenses it said were 20 percent larger than those of the first generation, with the glasses kit priced at US$149 (MSRP), together with a "3D LightBoost" display technology that it said delivered 3D images up to twice as bright as existing 3D solutions.[14] Sony added 3D support to the PlayStation 3 by a firmware update in June 2010.[12]
3D television and cinema
The largest consumer release of shutter glasses came in early 2010, when Samsung, Panasonic, Sony, LG, Sharp and other manufacturers launched 3D HDTVs.[1] Writing in 2011, PCWorld noted that most of these sets used LCD shutter glasses.[12] Because each brand used its own sync protocol, on 8 August 2011 Panasonic, Samsung, Sony and XpanD announced the Full HD 3D Glasses Initiative to standardize Bluetooth radio-frequency and infrared protocols between active glasses and TVs, PCs and projectors, with universal glasses planned for 2012 that would be backward compatible with 2011 active 3D TVs.[15]
3D television did not last. Samsung dropped 3D support in 2016, and LG and Sony removed it from their 2017 ranges. NPD Group figures for the United States put 3D sets at 8% of TV sales dollars in 2016, down from 23% in 2012.[4] LG's Tim Alessi said that research showed 3D was "not a top buying consideration" and that the company would focus on capabilities such as HDR instead.[16] NVIDIA's final driver with 3D Vision support was the Release 418 driver of April 2019, with critical fixes promised until April 2020.[5]
Shutter glasses were also used in some cinemas. A 2003 Invention & Technology article described IMAX's E3D glasses as containing a liquid crystal layer that switched from clear to opaque, synchronized by an infrared signal from the projection equipment.[3]
Timeline
| Year | Event |
|---|---|
| 1922 | Laurens Hammond's Teleview system uses synchronized mechanical shutter viewers for a stereoscopic feature film in New York[3] |
| 1983-1985 | StereoGraphics patent for a 120 Hz flickerless stereoscopic television system with occluding spectacles (filed 1983, granted 1985)[8] |
| 1987 | Famicom 3D System LCD shutter glasses released in Japan[12] |
| 1988 | Sega LCD shutter glasses for the Mark III and Master System[12] |
| 1993 | The CAVE paper describes frame-sequential stereo with StereoGraphics LCD shutter glasses on three wall screens and a floor screen[2] |
| 1997 | The two-user Responsive Workbench time-multiplexes four images for two viewers[6] |
| 1999 | ELSA and NVIDIA lead a second wave of PC stereo 3D[10] |
| 2009 | NVIDIA 3D Vision launches at CES[5] |
| 2010 | Consumer 3D HDTVs with active shutter glasses launch; PlayStation 3 gains 3D support[1][12] |
| 2011 | Full HD 3D Glasses Initiative announced; NVIDIA 3D Vision 2 announced; six-user C1x6 display published[15][14][17] |
| 2016-2017 | Samsung, then LG and Sony, drop 3D from their televisions[4] |
| 2019 | NVIDIA ends 3D Vision support with Release 418 drivers[5] |
Image quality and comfort
Crosstalk
Crosstalk, also called ghosting or leakage, is the leakage of the left image channel into the right eye's view and vice versa. In definitions quoted by Woods, crosstalk is a physical quantity that can be measured objectively, and ghosting is the perception of crosstalk.[7] In an active shutter system, crosstalk comes from the shutters (imperfect blocking, finite switching time and off-axis viewing), from the timing of the shutters relative to the display, and from the temporal behavior of the display:[7]
| Display type | Main crosstalk sources with shutter glasses |
|---|---|
| CRT | Phosphor persistence (afterglow) and shutter timing; because the electron beam scans from top to bottom, the bottom of the screen shows more ghosting than the top[7] |
| Plasma display | Phosphor persistence and shutter timing; phosphors can be fired up to 10 times per frame, so crosstalk depends on the grey level of each pixel[7] |
| LCD | Pixel response time, the top-to-bottom update method, shutter timing and duty cycle; crosstalk can vary across the screen[7] |
| DLP | Essentially none from the display itself, since the micromirrors switch in about 2 microseconds and the whole image changes at once; the remaining crosstalk comes from the glasses[7] |
Woods reports that ghosting is more visible in high-contrast images and with larger binocular parallax, and that published acceptability thresholds differ; examples he quotes include a visibility threshold of about 1 to 2% and a finding that about 5% crosstalk is enough to cause visual discomfort in half of the population. Crosstalk cancellation, which subtracts the expected leakage from each view before display, can hide small amounts of crosstalk but cannot remove large amounts.[7] The 1993 CAVE team ran into crosstalk directly: the green phosphor in commercial projection tubes persisted too long, so viewers saw both images and lost the stereo effect, and their 1991 experiments used only blue, red and shades of magenta until StereoGraphics supplied P43-coated green tubes by special order.[2]
Flicker and brightness
Because each eye sees the display only part of the time, the image rate per eye is a fraction of the display rate, and adding viewers reduces it further. Agrawala and colleagues reported slight but noticeable flicker in their two-user system, which ran at 144 Hz and so gave each eye of each user 36 images per second, and noted that half of the frames each user saw were black, reducing perceived brightness.[6]
Visual comfort
In a crossover study of 30 participants aged 20 to 30 published in Acta Ophthalmologica in 2013, Zhang and colleagues compared a shutter-glasses 3D display with a pattern-retarder (passive polarized) 3D display. After watching a video on the shutter-glasses display, participants had a significantly higher subjective visual fatigue score (1.65 versus 1.20) and significantly smaller values on several accommodation and convergence measures.[18] In a 2015 subjective test of four 55-inch consumer televisions (one autostereoscopic, one with passive polarized glasses and two with active shutter glasses), Gutiérrez, Jaureguizar and García reported high quality and comfort for the polarized-glasses technology, a performance improvement for active shutter glasses technology, and a need for the autostereoscopic display to improve in visual comfort.[19]
Applications in VR and AR
Projection VR and the CAVE
The original CAVE, built at the University of Illinois at Chicago by Carolina Cruz-Neira, Daniel J. Sandin and Thomas A. DeFanti, used frame-sequential stereo. Its projectors threw 1280x512 stereo fields at 120 Hz onto three wall screens and a floor screen, and StereoGraphics LCD shutter glasses, triggered by infrared transmitters, kept each lens transparent for the proper 512 lines of the 1280x1024 image and switched during the vertical retrace. The system produced 120 fields per second and updated the whole image at 60 Hz, which the authors describe as flicker-free.[2] The same paper listed "moving the shutters from the eyes to the projectors so cheap cardboard polarizing glasses can be used" as one of the unsolved problems of the design.[2]
A 2021 survey of 3D displays by Pan, Xu, Dev and Campbell groups these systems as glasses-required displays and distinguishes three kinds of eyewear: color-multiplexed (anaglyph), polarization-multiplexed (polarized) and time-multiplexed (shutter) glasses. It notes that when such a display serves a single tracked viewer, the projection can be recalculated from the viewer's position to give motion parallax, as in the CAVE and in Deering's adapted CRT monitor with time-multiplexed eyewear and a head tracker, a type of desktop system that Ware named fish tank VR.[20] Not every tracked stereo desktop uses shutters: the zSpace 200, for example, used passive polarized eyewear with head tracking.[21]
Multi-user stereo
Time multiplexing can also give several co-located users their own perspective-correct stereo views on one screen. In 1997 Maneesh Agrawala, Andrew Beers, Ian McDowall, Bernd Fröhlich, Mark Bolas and Pat Hanrahan extended the Responsive Workbench to two users by rendering four images, one for each eye of each user, and showing them in sequence. They modified the shutter glasses to add a third state with both eyes closed while the other user's images were displayed. Their hardware ran at 1280x492 pixels at 144 Hz or 1024x768 at 120 Hz; flicker was less noticeable when the two users' frames were interleaved than when each user's two frames were shown back to back. The authors named flicker, crosstalk from CRT phosphor decay, and reduced brightness as the limits of the approach.[6]
In 2011 a team at Bauhaus-Universität Weimar presented C1x6, a stereoscopic display for up to six tracked users that combined six customized DLP projectors for fast time-sequential display with polarization. Its high-speed shutter glasses could be programmed by the application, for example to stay open when a user was not looking at the screen or to switch to a brighter mode when fewer than six people were using the system.[17]
Relation to head-mounted displays
Active shutter glasses separate two views on a shared screen. A head-mounted display places a separate image in front of each eye, so it does not need shutter glasses to deliver binocular disparity; Pan and colleagues treat HMDs and glasses-required displays as separate classes of 3D display.[20] When NVIDIA ended 3D Vision support in 2019, it said its users and the industry had moved to newer immersive experiences such as virtual reality and that it would focus driver support on those technologies.[5]
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Andrew J. Woods, Jesse Helliwell (2012-01). "Investigating the cross-compatibility of IR-controlled active shutter glasses". Proc. SPIE 8288, Stereoscopic Displays and Applications XXIII. SPIE and IS&T. doi:10.1117/12.912061. https://cmst.curtin.edu.au/wp-content/uploads/sites/4/2016/05/2012-28-woods-helliwell-cross-compatibility_of_shutter_glasses.pdf. Retrieved 2026-10-06.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Carolina Cruz-Neira, Daniel J. Sandin, Thomas A. DeFanti (1993). "Surround-Screen Projection-Based Virtual Reality: The Design and Implementation of the CAVE". Proceedings of SIGGRAPH '93, pp. 135-142. ACM. doi:10.1145/166117.166134. https://www.evl.uic.edu/documents/siggraph93-cave-cruz-neira.pdf. Retrieved 2026-10-06.
- ↑ 3.0 3.1 3.2 3.3 Tom Huntington (2003). "The Gimmick That Ate Hollywood". Invention & Technology, vol. 18, no. 4. https://www.inventionandtech.com/content/gimmick-ate-hollywood-0. Retrieved 2026-10-06.
- ↑ 4.0 4.1 4.2 Jon Bragg (2017-01-25). "3D TV Is No More As LG And Sony Cease Production". ChannelNews. https://www.channelnews.com.au/3d-tv-is-no-more-as-lg-and-sony-cease-production/. Retrieved 2026-10-06.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Jon Fingas (2019-03-11). "NVIDIA will stop supporting 3D glasses in April". Engadget. https://www.engadget.com/2019-03-11-nvidia-ends-3d-vision-support.html. Retrieved 2026-10-06.
- ↑ 6.0 6.1 6.2 6.3 Maneesh Agrawala, Andrew C. Beers, Ian McDowall, Bernd Fröhlich, Mark Bolas, Pat Hanrahan (1997-07). "The Two-User Responsive Workbench: Support for Collaboration Through Individual Views of a Shared Space". Proceedings of SIGGRAPH '97, pp. 327-332. ACM. doi:10.1145/258734.258875. http://vis.berkeley.edu/papers/twouserrwb/twouserrwb.pdf. Retrieved 2026-10-06.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Andrew Woods (2010-05). "Understanding Crosstalk in Stereoscopic Displays". Keynote, 3DSA (Three-Dimensional Systems and Applications) conference, Tokyo. http://cmst.curtin.edu.au/wp-content/uploads/sites/4/2016/05/2010-23_understanding_crosstalk_woods.pdf. Retrieved 2026-10-06.
- ↑ 8.0 8.1 Lenny Lipton, Michael R. Starks, James D. Stewart, Lawrence D. Meyer (1985-06-11). "US4523226A - Stereoscopic television system". Google Patents. United States Patent and Trademark Office. https://patents.google.com/patent/US4523226A/en. Retrieved 2026-10-06.
- ↑ "Once a physicist: Lenny Lipton". Physics World. IOP Publishing. 2007-07-02. https://physicsworld.com/a/once-a-physicist-lenny-lipton/. Retrieved 2026-10-06.
- ↑ 10.0 10.1 10.2 Jon Peddie (2024-10-10). "Remember Stereo 3D on the PC? Have You Ever Wondered What Happened to It?". ACM SIGGRAPH Blog. https://blog.siggraph.org/2024/10/stereo-3d-pc-history-decline.html/. Retrieved 2026-10-06.
- ↑ Lenny Lipton, Jeffrey J. Halnon, Larry H. Mitchell, Robert Hursey (1995-10-31). "US5463428A - Wireless active eyewear for stereoscopic applications". Google Patents. United States Patent and Trademark Office. https://patents.google.com/patent/US5463428A/en. Retrieved 2026-10-06.
- ↑ 12.0 12.1 12.2 12.3 12.4 12.5 Benj Edwards (2011-03-03). "The History of Stereoscopic 3D Gaming". PCWorld. https://www.pcworld.com/article/495252/the_history_of_steroscopic_3d_gaming.html. Retrieved 2026-10-06.
- ↑ John Yan (2009-12-08). "NVIDIA GeForce 3D Vision Review". Gaming Nexus. https://www.gamingnexus.com/Article/2424/NVIDIA-GeForce-3D-Vision. Retrieved 2026-10-06.
- ↑ 14.0 14.1 "NVIDIA 3D Vision Vaults to New Dimension With Next-Gen 3D Glasses and Monitors". NVIDIA Newsroom. NVIDIA. 2011-10-14. https://nvidianews.nvidia.com/news/nvidia-3d-vision-vaults-to-new-dimension-with-next-gen-3d-glasses-and-monitors. Retrieved 2026-10-06.
- ↑ 15.0 15.1 Richard Lawler (2011-08-08). "Panasonic, Sony, Samsung and XpanD finally team up for an active 3D glasses standard". Engadget. https://www.engadget.com/2011-08-08-panasonic-sony-samsung-and-xpand-finally-team-up-for-an-active.html. Retrieved 2026-10-06.
- ↑ John Biggs (2017-01-25). "3D TVs are dead". TechCrunch. https://techcrunch.com/2017/01/25/3d-tvs-are-dead. Retrieved 2026-10-06.
- ↑ 17.0 17.1 Alexander Kulik, André Kunert, Stephan Beck, Roman Reichel, Roland Blach, Armin Zink, Bernd Froehlich (2011-12). "C1x6: A Stereoscopic Six-User Display for Co-located Collaboration in Shared Virtual Environments". ACM Transactions on Graphics, vol. 30, no. 6, article 188. Bauhaus-Universität Weimar. doi:10.1145/2070781.2024222. https://www.uni-weimar.de/en/media/chairs/computer-science-department/vr/research/multi-user-virtual-reality/c1x6-a-stereoscopic-six-user-display/. Retrieved 2026-10-06.
- ↑ L. Zhang, Y. Q. Zhang, J. S. Zhang, L. Xu, J. B. Jonas (2013). "Visual fatigue and discomfort after stereoscopic display viewing". Acta Ophthalmologica, vol. 91, no. 2, pp. e149-e153. doi:10.1111/aos.12006. https://doi.org/10.1111/aos.12006. Retrieved 2026-10-06.
- ↑ Jesús Gutiérrez, Fernando Jaureguizar, Narciso García (2015). "Subjective Comparison of Consumer Television Technologies for 3D Visualization". Journal of Display Technology, vol. 11, no. 11, pp. 967-974. https://opg.optica.org/jdt/abstract.cfm?uri=jdt-11-11-967. Retrieved 2026-10-06.
- ↑ 20.0 20.1 Xingyu Pan, Xuanhui Xu, Soumyabrata Dev, Abraham G. Campbell (2021-05-18). "3D Displays: Their Evolution, Inherent Challenges & Future Perspectives". Future Technologies Conference (FTC) 2021; arXiv 2105.08390. https://arxiv.org/abs/2105.08390. Retrieved 2026-10-06.
- ↑ "Introducing the zSpace 200 (technical specifications)". zSpace. zSpace, Inc.. https://cdn.zspace.com/downloads/documentation/specifications/zSpace200TechSpecs_113015.pdf. Retrieved 2026-10-06.