How to Design Light Pipes导光柱设计实例精讲外文资料.docx

How to Design Light Pipes导光柱设计实例精讲外文资料.docx

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HowtoDesignLightPipes导光柱设计实例精讲外文资料

LearnbyExample:

HowtoDesignLightPipes

Lightplaysanimportantroleinthedesignofmanyhardwareproducts.Often,theyarebothdecorativeandfunctional.Indicatorlightsarethemostminimaluserinterface:

Theytellyouwhetherthedeviceisturnedon,lowonbattery,or“thinking”reallyhard.

Onmodernelectronics,thelight’ssourceisalmostalwaysanLED.However,yourarelyseeexposedLEDcomponentsontheexteriorofadevice.Whatyou do seeistheexitsurfaceofalightpipe（alsoknownasalightguide）.

Lightpipescanfocus,diffuse,orredirectlight;mostlightpipesdosomecombinationofthese.

Designconsiderationsinclude:

∙Minimizinglossduringtransmission

∙MinimizingthenumberofLEDsneeded（theyarepower-hungrycomponentsthatdestroybatterylife）

∙MaximizingcolormixingforRGBLEDs

Inour teardowns,we’veseenmanylightpipes—they’reoneofourfavoritetypesofcomponentsbecauseeachoneissounique.Today,wewanttodigdeeperintosomeuniquelightpipeapplicationsandexplaintheprinciplesbehindeachdesign.

Application1:

ExtendingLight’sReach

AsImentioned,LEDsarepower-hungrycomponents.Soforportableelectronics,youshouldonlyusethelightwhentheuserisactivelyinteractingwiththedevice,andyou’llwanttominimizethenumberofLEDsneeded.LightpipescanbeusedtoextendthereachofLEDssoyoucanusefewertoachievethesameilluminationeffect.Herearetwoexamplesofhowlightpipesilluminatelogosandthumbpads.

Example1:

IlluminatedLogoof UnderArmourHeartRateMonitor

TheUAheartratemonitor’sfrontcoverfeaturesasizeablelogo.Theengineersbehindthisproductmanagedtolightupthislogoevenly,withjustonetinytop-firingLEDatthecenterofthemainPCBA.ThisLEDdoesn’thavemuchreachbyitself.

UnderArmourLED 

Enterthelightpipe:

It’smadeofamilkyplasticthatcouldbepolycarbonateresin（normallytransparent）withaddedtitaniumdioxide.Themoretitaniumdioxidethat’sadded,themoremilkytheplastic,whichimprovesdiffusion.

Thecone-shapedcavityfeatureatthecenterofthelightpipeisdesignedtomatchtheLED;theangularwalloftheconehelpstodirecttheemittedlightintothelightpipe.

Theconeistheentrypointofthelightpipe,andtheentrypointshouldalwaysbeplacedasclosetothelightsourceaspossible,tominimizeloss.

Lightpipediffuser 

Let’sseetheactualeffectofthelightpipe:

1.Withoutthelightpipe,thereisastronghotspotinthecenterofthelogoandnotmuchlightelsewhere.

2.Withthelightpipe,thelightemittedbytheLEDisspreadoutmoreevenlyandtheextremehotspotisgone.

UnderArmourLEDwithoutlightpipe 

UnderArmourLEDwithlightpipe 

Example2:

IlluminatedThumbPadof LogitechG600MMOMouse

TheLogitechG600MMOmousehasatwelve-buttonthumbpad.Eachkeyisbacklit,andtheusercancustomizethelight’scolor.HowmanyLEDsdoyouthinkareusedtolightupallthesekeys?

TheanswerisTWO!

Isn’tthatsurprising?

Whatwizardry!

Thesecretisside-firingLEDsthatemitlightdirectlyintoaflatplateofalightpipe.NoticehowclosetheentrypointofthelightpipeistotheLEDs.Youcan’taffordlosseswhenthelightshavealongwaytogototheirexitpoints.

Noticehowtheopposingelastomerthumbpadparthasblackpaintspotsonsomekeys,butnotothers?

TheseblackspotsareclosetotheLED,likelytomaskhotspots.

Alsonotethatthelightpipeplateissuperglossy,andthesurfacesencapsulatingthelightpipe’stopandbottomsidesarebothwhite.Bothofthesefeatureshelpmaximizethetotalinternalreflectionandimprovecolormixing.

Application2-BendingLight

LEDscannotalwaysbelocatedrightbehindtheintendedexitpointofthelights,solightpipesareoftenusedtotransportlightemittedbyaboard-mountedLEDtoanexitwindowsomedistanceaway.Theycaneven“bend”light,aslongasit’swithinthelimitationsofphysics.

Hereareafewexamples:

Example1:

 Neato Light“Arc”

ThislightpipecradlestheNeato’spowerbutton.IthastwoentrypointsforLEDstoilluminatetheentirepathevenly.ThesecondLEDisneededbecauselightdoesnotliketobendpast90degrees.IfonlyoneLEDwereused,significantlosswouldhappenwherethesecondentrypointis,andtheendofthearcwouldbedark.

TheentrypointsofthelightpipematchtheshapeoftheLEDswell.

Neatolightpipe 

Notethatthetopsurfaceofthelightpipeistextured,whereasalltheothersurfacesareglossy.Texturedsurfacesencouragelighttoexit,andglossysurfacesencourageinternalreflection.

Alsonotethataluminumfoilcoverstheundersideofthelightpipe.Thishastwopurposes:

1.Tomaximizetotalinternalreflection

2.Topreventusersfromseeinginternalcomponentsunderneaththelightpipe

Example2:

 TiVoBolt StatusLights

TheTiVoBolthasfivestatusindicatorlights.Forallofthese,thelightsourcehadtobe“bent”throughlightpipestoexittheenclosure.

Oneoftheseisaveryclassic“lightpipe,”aclearpolycarbonatetubethat’sslightlybenttotransportlightfromthesourcetotheexitpointatthelogo.Theentrypointisaflatsurface—thisisalightpipethathasnotbeenmatchedtotheLED,incurringbrightnessloss.However,thissimplifiestheinjectionmoldtoolingofthelightpipe.

TiVolightpipe

Theotherfourindicatorlightsappearinarow.

TiVoindicatorlights 

Thisset-upusesamulti-unitlightpipe—thinkofthisasamulti-laneroadway!

Each“roadway”hasitsownentryandexitpoints.Thelightsourcesarefoursurface-mountedLEDsinarow.

Thelightpipeiscoveredbyatwo-pieceblackshroud,whicheliminateslightleakage.SincetheTiVoBoltenclosureiswhite（notlight-proof）,withouttheshroud,wewouldn’tbeabletoseeeachlightdistinctly.

Lightpipeshroud 

MainTakeaways

Wehopeyouenjoyedthis“anthology”oflightpipeexamples.Putyourownspinontheseestablisheddesigns,andaddsomeshinytoyournextproject!

 Nowthatyouhaveformfactorinspiration,checkoutour guidetoprototypinglightpipeswith3Dprinting.