2011 17 Woods Helliwell 3D Sync IR

8/12/2019 2011 17 Woods Helliwell 3D Sync IR

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WhitePaper:

ASurveyof3DSyncIRProtocols

AndrewWoodsandJesseHelliwell

CurtinUniversity

PROJECT:CMST944

REPORT:C201117version1

ISSUED:31March2011

CENTREFORMARINESCIENCEANDTECHNOLOGY

CURTINUNIVERSITY

PERTH,WESTERN

AUSTRALIA

www.cmst.curtin.edu.au www.AndrewWoods3D.com


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Woods,Helliwell(2011)ASurveyof3DSyncIRProtocolsWhitePaper. 2

Contents

Introduction ............................................................................................................................................3TestingMethod ....................................................................................................................................... 43DSyncProtocolsSummary ...................................................................................................................5CrystalEyesProtocol(Standaloneemitter) ............................................................................................6NuVisionProtocol(Standaloneemitter)................................................................................................7XpandProtocol(Standaloneemitter) ....................................................................................................8H3D/ELSAprotocol(Standaloneemitter) ............................................................................................9NVIDIAProtocol(Standaloneemitter).................................................................................................10Samsung2007Protocol(Standaloneemitter).....................................................................................11Samsung2010Protocol(InternalTVEmitter).......................................................................................11PanasonicProtocol(InternalTVemitter)..............................................................................................12SonyProtocol(Standaloneemitter).....................................................................................................13DLPLinkProtocol(visiblelight internal) ..........................................................................................14Discussion .............................................................................................................................................15Conclusion.............................................................................................................................................16Acknowledgements...............................................................................................................................16References.............................................................................................................................................16


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Introduction

ThepurposeofthisdocumentistosummarisethedifferentIRcommunicationprotocolsusedbya

selectionofcommerciallyavailablestereoscopic3DActiveShutterGlasses.

ActiveShutterGlasses(alsoknownasLiquidCrystalShutter(LCS)3DglassesorjustShutterGlasses)

areacommonlyusedselectiondeviceusedtoviewstereoscopic3Dcontentontimesequential

stereoscopicdisplays. Timesequentialstereoscopic3Ddisplaysoperatebydisplayingdiscreteleft

andrightimagesinalternatingsequenceoftenatimageratesof100,120or144imagespersecond.

Thistimesequentialapproachcanalsobedescribedastimemultiplexed. Theactiveshutterglasses

alternatelyblanktheleftandrighteyesinsequencewiththesequenceofimagesshownonthe

displaysuchthatthelefteyeonlyseestheleftperspectiveimagesandtherighteyeonlyseesthe

rightperspectiveimages. Theactiveshutterglassesusuallycontaintwoliquidcrystalcells,each

actingasashutteroneinfrontofeacheye.

Inorderfortheactiveshutterglassestoswitchinsynchronywiththesequenceofleftandright

imagespresentedonthetimesequentialstereoscopicdisplay,someformoftimingsignalmustbe

sentfromthedisplaytotheglasses. Mostwirelessactiveshutterglassesuseaninfrared(IR)

communicationprotocolsimilartothatusedforIRremotecontrolsusedforTVs,airconditionersand

otherconsumerelectronics. SomeglassesuseanRF(radiofrequency)communicationprotocolsuch

asBluetoothorZigBee,howevertheseareoutsidethescopeofthisdocument. TheDLPLink

protocolusespulsesofvisiblelightinitsprotocol.

Activeshutterglasseshavebeenusedasaviewingdevicefortimesequentialstereoscopicdisplays

asfarbackas1922fortheTeleviewsystem1. Thefirstwirelessactiveshutterglassesappeartobe

theStereoGraphicsCrystalEyeswhichwerereleasedinthemid80s,usedliquidcrystalshutters,and

anIRcommunicationprotocolforsynchronisation. SeveralotherbrandsanddesignsofIRcontrolled

wirelessactiveshutterglasseshavebeenreleasedovertheyears2andinearly2010thelargest

consumerreleaseofactiveshutterglassesoccurredwiththeconsumerreleaseof3DHDTVsby

severalconsumerelectronicsmanufacturers(includingSamsung,Panasonic,Sony,LG,Sharp,and

others3.)

RegrettablymostoftheIRcontrolledactiveshutterglassesreleasedtodatebyvarious

manufacturershaveusedavarietyofdifferentIRcommunicationprotocolswhichmeansthatactive

shutterglassesfromonemanufactureraregenerallynotcrosscompatiblewithanother. For

example,apairofPanasonicactiveshutterglassescannotbeuseddirectlywithaSamsung3DHDTV,

andviceversa.

Thereasonfortheincompatibilitybetweendifferentmakesofactiveshutterglassesmostlyrelatesto

differencesbetweentheactualIRcommunicationprotocolusedforeachbrandofglasses,butthere

arethreeotherpossiblereasonsforincompatibility:(1)someglassesuseRForvisiblelight

communicationslinkinsteadofIR,(2)somedisplaysneedtheglassestoswitchwithareducedduty

cycleforcorrectoperationandonlysomeglassesoperatethisway,(3)someglasses(i.e.Sony)dont

haveafrontpolariserontheshutterandrelyonthedisplaytooutputlinearpolarisedlight.

Amongstthe

active

shutter

glasses

that

use

an

IR

communication

protocol,

there

is

very

little

informationinthepublishedliteratureastohowthevariousprotocolsdiffer. In2010,weinitiateda


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projecttocharacterizethespecificsofawiderangeof3DSyncIRprotocolssoastogainan

understandingofwhyvariousactiveshutterglassesareincompatible,howandwhytheprotocols

differ,whatlimitationstheremightbeincreatingasinglestandard3DSyncIRprotocol,andthe

possibilityfordisplaydevicestooutputmultipleprotocolsatthesametimesothatmultiplemakesof

shutterglassescanbeusedwiththeonedisplay.

Thisdocumentsummarisesthe3DSyncIRprotocolasusedbyaselectionofemittersandglasses.

Theprotocolsummariesprovidedherearederivedfromthemeasurementoftheactualprotocol

signaloutputbyaselectionofcommerciallyavailableproducts. Theprotocolsummariesprovided

herearenotderivedfromanydocumentationdefinedbyindividualmanufacturersandhencedoes

notincludeanyinformationontimingtolerancesorperhapsadvancedtimingspecifics. The

manufacturershavenotprovidedanyoftheprotocoltiminginformationdescribedinthisdocument.

Atotaloftenprotocolswerecharacterisedinthisstudy.

TestingMethod

Theprotocolsweremeasuredbyconnectingtheemitter/dongleor3Ddisplay/projectortoa3D

videoor3Dsyncsource. Inthecasewheretheemitterwasintegratedintothe3Ddisplay/projector,

the3Ddisplay/projectorwasswitchedinto3Dmode. AhighspeedIRphotosensorwasdirectedat

theIRemitterandanalysedusingadigitalstorageoscilloscope. ThetimingoftheIRpulseswere

measuredrelativetothe3DSyncsignal,thelightfieldemittedbythedisplay,and/orthetimingof

theshutteringoftheeyewear.

Theten

pairs

of

active

shutter

glasses

tested

in

this

study

are

shown

in

Figure

1.

Some

of

the

emitterstestedinthisstudyareshowninFigure2.

Figure1:Thetenactiveshutterglassestestedinthisstudy:(a)StereoGraphicsCrystaleyesCE1,(b)ELSA/H3D,

(c) NuVision60GX,(d)NVIDIA3DVision,(e)PanasonicTYEW3D10U,(f)Samsung2007,(g)Samsung(2010)

SSG2100AB,(h)SonyTDGBR100,(i)ViewsonicPGD150DLPLink,(j)XpandX103Universal.


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Figure2: SomeofthestandaloneIR3Demitterstested:(a)Samsung2007,(b)NuVision,(c)NVIDIA,

(d)CrystalEyes

1,

and

(e)

H3D/ELSA.

Inordertoverifytheaccuracyoftheprotocolmeasurements,acustombuiltuniversalIRemitterwas

constructed4andusedtosendaregeneratedversionofthevariousIRprotocolstothevariousactive

shutterglasses. Wewereabletoreliablydriveallofthetestedactiveshutterglassesusingthe

appropriatemeasuredIRprotocol. Therewasonlyoneexceptiontothistesting,whichwasthatwe

wereunabletoreliablydrivetheXpandX103universalglassesintheSamsung(2010)protocolmode

usingourregeneratedSamsung2010protocol. Thismightindicateaslighttimingerrorinour

measurementoftheSamsung2010protocol,howeverwewereabletousethisprotocoltimingto

driveanactualpairoftheSamsung2010activeshutterglasses.

3DSyncProtocolsSummary

Thetimingdiagramsforthetenprotocolsmeasuredinthisstudyaredetailedbelow.

Itisimportanttopointoutthat:

notallofthediagramsaredrawntoscale.

thetimingsareasmeasuredfromcommerciallyreleasedhardwareandwerenot

providedorendorsedbythemanufacturers.

theremightbetimingerrors inthedescriptions.

theSamsungandDLPLinkprotocolshaveasubtlydifferentmodeofoperationwhich

aredetailedbelow.

allunitsareinmicroseconds(s)

thetimingoftheopeningandclosingoftheleftandrightshuttersarenotindicated

inthesediagramsanddonotnecessarycoincideexactlywiththetimingofthe

tokens. Thesetimingswillbethesubjectofafuturepublication.


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NuVisionProtocol(Standaloneemitter)


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XpandProtocol(Standaloneemitter)


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H3D/ELSAprotocol(Standaloneemitter)


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NVIDIAProtocol(Standaloneemitter)

30.7523.25

23.25 23.75

43.25

39.7523.25

78.25

21.1

46.2

Close Right Eye

Open Left Eye

Close Left Eye

Open Right Eye

Notes:

Thisisafourtokenprotocolandhenceallowsthedisplaytospecifythedutycycleforthe

glassesto

operate.


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Samsung2007Protocol(Standaloneemitter)

14.2

12.1 12.1Open Right Eye,

Close Left Eye

Then Open Left

Eye, Close RightEye

14.2 14.2

Samsung2010Protocol(InternalTVEmitter)

Notes:

BoththeSamsung2007andtheSamsung2010protocolsareaonetokenprotocol. The

Samsung2007tokenisoutputonceeveryright+leftframepairperiod(atthebeginningof

therightframeperiod)andtheSamsung2010protocolonceeverytworight+leftframepair

periods. Theglassesmustassumeadutycycleofapproximately50%andcalculatethe

intermediatetiming

internally.


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PanasonicProtocol(InternalTVemitter)

20

60

Close Right Eye

Open Left Eye

Close Left Eye

Open Right Eye

20

20

20

60

20

163 before open left eye

20

60

20 20

60

20

20

20

60

20 20

60

20

20

20

100

20 20

20

20

20

163 before open right eye

Notes:


glassestooperate.


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SonyProtocol(Standaloneemitter)

Notes:


glassestooperate.


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DLPLinkProtocol(visiblelight internal)

Notes:

Thelefteyetokenandtherighteyetokendonotdifferinwidth,butinrelativetiming. The

righteyetokenisdelayedrelativetothesyncreferenceby260sascomparedtothetiming

ofthelefteyepulse. Anotherwayofinterpretingthisistosaythatthetimingbetween

pulsesfortherightperspectiveimageperiodis520s(2260s)lessthanthetiming

betweenpulsesfortheleftperspectiveimageperiod.

AspectsofthisprotocolappeartobethesubjectofUSPatentApplication2008/0151112A1.


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Discussion

Asmentionedabove,oneofthemaindifferencesbetweenthevariousprotocolsisthenumberof

tokensassummarisedinTable1.

Table1:Thenumberoftokensusedbythevarious3DSyncprotocols.

Glasses Tokens Glasses Tokens

NuVision 2 DLPLink 2

Xpand 2 Samsung2007 1

Elsa/H3D 2 Samsung2010 1

CrystalEyes 2 NVIDIA 4

Panasonic 4 Sony 4

Itisworthnotingthatthe4tokenprotocolsarecapableofbeingusedtoimplementreducedduty

cycleoperationoftheglasseswhichisnecessaryforsomedisplaysforoptimalperformance. Theuse

ofa4tokenprotocolwouldthereforeseemtoofferthemostflexibility.

Thereisalotofvariationintherelativecomplexityofthevariousprotocolssomeuseasimple

singlepulseforeachtokenwhereasothersuseacombinationofpulsesandsomeusemorepulses

thanothers. Theglassesthatuseamorecomplextokenarelesslikelytobemistriggeredby

spuriousIRsignalsandrejectotherIRsignals,howeveramorecomplextokenalsohasmorechance

ofbeinginterferedbecauseithasalongerperiod.

Somethingthatisnotrevealedbytheseresultsisthetoleranceforsignaltimingvariationofthe

variousglasses. Aconsiderableamountofadditionaltestingwouldbeneededtoestablishthisand

thenitwouldonlybevalidforaparticularsetofglasses. Obviouslyinputfromthemanufacturers

wouldbenecessarytoestablishthistolerancecorrectly. Oneexampleofthistoleranceisthatthe

NuVision60GXglassescansuccessfullysynctotheXpandprotocol,buttheXpandX103glasseswill

notaccepttheNuVisionprotocol.

Tighttolerancewouldmeanthatapairofglasseswouldbelesslikelytobetriggeredormistriggered

bytheprotocolmeantforanotherpairofglasses.

Anotherreasonforwantingtoestablishprotocoltimingtoleranceistoworkoutwhetheroneglasses

protocolmightdriveormistriggeranothersetofglasses. Thisisimportanttoknowsothatitcanbe

determinedwhetheraTVcansuccessfullyoutputmultipleprotocolstodrivemultiplebrandsof

glassesatthesametime.

Thecrosscompatibilityofprotocolsisalsodeterminedbythesimilarityofthenumberandtimingof

thepulses. Forexample,ithasalreadybeenestablishedthattheXpandandSamsung2010protocols

wontcoexistbecausebothprotocolsuseathreepulseprotocolwithsimilarpulsewidthsbutwith

oppositepolarity. Amoreextensiveanalysisofcrosscompatibilitywillbethesubjectofafuture

publication.


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Conclusion

Theanalysisofthevarious3DSyncIRprotocolshascertainlybeenaninterestingrevelationintowhat

isnormallyaninvisibleprocess. Theresultshaverevealedaconsiderableamountofvariation

betweenprotocols

and

also

some

overlap.

It

is

hoped

that

the

results

of

this

paper

will

provide

usefulbackgroundinformationtowardsthedefinitionofasinglestandardforactiveshutterglasses.

Pleasenotethattheprotocolmeasurementsoutlinedinthedocumenthavebeenprovidedfor

researchanddiscussionpurposesonly. Theprotocolmeasurementsmaybesubjecttoerrorand

shouldnotbeusedasanactualtechnicaldefinitionoftheprotocols.

Acknowledgements

Wewish

to

acknowledge

the

support

of

iVEC

in

conducting

this

research.

Productnamesandtrademarksarethepropertyoftheirrespectiveowners.

References

1. DanielL.Symmes(2006)TheChopper

Online:http://www.3dmovingpictures.com/chopper.html

Dated:14November2006. Accessed:29March2011.

2. ChristophBungert(2005)ShutterglassesComparisonChart

Online:http://stereo3d.com/shutter.htm

Dated:1April2005. Accessed: 29March2011.

3. AndrewJ.Woods(2011)TheIllustrated3DReadyHDTVlist

Online:www.3dmovielist.com/3dhdtvs.html

Dated:28March2011.Accessed:29March2011.

4. Petrus(2011)UniversalsutterglassescontrollerinMTBS3DForums.

Online:http://www.mtbs3d.com/phpBB/viewtopic.php?p=55149#p55149

Dated:10Jan2011. Accessed:29March2011.

5. GregoryR.Basile,FrankJ.Poradish(2006)SystemandMethodforSynchronizingaViewing

DeviceUSPatentApplication2008/0151112A1,dated22Dec2006.

Documents

2011 17 Woods Helliwell 3D Sync IR