Upload
tranxuyen
View
220
Download
0
Embed Size (px)
Citation preview
HowtoMakeaHeadStickPointerforiPhone
ResearchersonProject:BenChater,Geoffrey
Edwards,ErikJakobsandJerryRussell
Background
InvoTekwascontactedthroughtheRERCbyBenChaterwhowantedtobeabletoaccesshisiPhoneusinghisheadstick.Bentriedusinga
commercialstylusdevelopedfortheiPhonebutitdidnotworkreliablyforhim.WestartedtestingusingoniPodTouch2Gwhichhasthesame
capacitivetouchscreenasaniPhone.Throughoutthedesignprocess,weworkedcloselywithBenviaemail.Benprovidedguidanceonhowour
intermediatedesignsworkedforhim.Healsoprovideddesignideastoimproveusability.
Afteracoupleoftestswhichincludedsandingtheendoftheheadstickandcoveringawoodenballwithconductivematerial,Geoffrecommendedthatwetryusingconductivefoamthatwehadinour
electronicsworkshop.Thefoamworkedwell.Wedeterminedthatthesurfaceareaofthefoamtouchingthescreenwasimportantforreliableoperation.Weexperimentallydeterminedthat3/8‐inchdiameterworks,butisnotcompletelyreliable,while½‐inchdiameterworksreliably.
Whatisneededforcreatingaconductivetipforaheadstick
1. Conductivefoam‐availablefromDigikey
2. ¼inchcoppertubing–availablefromanyautosupplystore3. PlastiDipbyPerfomix–availablefromLowe’s4. ¼starwasher–availablefromanyhardwarestore.
5. Solderironandsolder6. HeatGunandheatshrink
Measurementsmaybedifferentforyourspecificheadstickassembly.Ben’s,whichweusedforthemeasurements,isonethathehasbeenusingforalongtimeandhaspartsfromanumberof
differentplaces.TheassemblyispicturedbelowattheendofthearticlewhilebeingtestedbyErik.
Directionstoassemble
1. Cuta3inchlongsectionof¼inchcoppertubing.Thisisgoingtobebackboneofthetipwhichwillinsertintotheheadstickandcontaintheconductivefoamononeend.
2. Solder4linesabout13/8incheslongalongtheendthatwillnotbecoveredinfoam.Beforesoldering,makesuretocleanthecopperbyrubbingitwithfinesandpaperandwipingitdown
withrubbingalcohol.Thisholdsthetipsteadierwhenitisinsertedintotheheadstick.
3. Solder¼inchstarwasher(flattened)about3/4inchfromtheendthatwillcontainthefoam.Be
suretocleanthecopperwhereyousolderthesameasabove.Thiswillbeusedasanedgeto
helptheusermoveobjects.Aviceliketheoneinthepicturebelowisusefulsothatfingersarenotburnedwhilesolderingtothecopper.
4. Cuta1‐1/4inchsquareof1/8inchconductivefoam.Thethicknessofthefoamisimportantsinceitisthedecidingfactorinthesizeofthetipofthepointer.Thesizeofthesquareisalsoimportantbecausetheremustbeenoughtomakethearmslongenough(describedbelow)to
holdthefoaminplace.
Ifyouhave¼inchconductivefoam:a. Cutthe1‐1/4inchsquareasdescribedabove.b. Cutthethicknessofthefoaminhalfsothatitisthesamethicknessasitwouldbeifyou
had1/8inchfoam.
5. CutthefoamintotheformofanXwhereeacharmisaboutthewidthofthetubing(seepicturebelow).Bycuttingthefoamintothisshape,therearenotbulgesonthesidesofthepointer.
6. Applyadotofhotglueontheendofthetubingthatthefoamwillbeplacedandletdry.This
roundsthetipofthetubingsothatthecopperwillnotcutthroughthefoamandscratchthescreenortrackpaditisbeingusedon.
7. Oncetheglueisdry,applyanothersmallamountofglueandputthefoamonthetip.Thiswillhelpthefoamstayinplaceonthepointer.
8. Bendall4armsofthefoamdownandholdthemdownwithapieceof½inchdiameterheat
shrink.Theheatshrinkshouldbeabout1inchlongsothatonlyasmallamountofthefoamisexposedontheendanditextendspastthewasher.Theheatshrinkhastwopurposes:
a. Asitisheateditreducesthediameterofthefoamtip.
b. Itextendspastthewasherwhichhelpsholdthefoaminplace(inadditiontothegluedot).
9. Heattheheatshrinkstartingtowardtheexposedfoamandmovingtowardthewasherwhilerotatingthetubing.Thereasontoheattheexposedfoamsidefirstisthatwhileitshrinkswedon’twantittoexposemorefoam(whichhappensifitisheatedfromthewashersidefirst).By
heatingitthisway,thefoamissqueezedtightandthentheheatshrinkpullsthefoamtowardthewasher.
10. ThenextstepistocovertheheatshrinktubingwithPlastiDip.ThePlastiDipisasprayonrubberwhichallowstheusertohavemoregripwhenusingthewasheredge.Oncetheheatshrinkisthecorrectdiameter:
a. Covertheexposedfoamwithmaskingtape.IfthefoamiscoveredwithPlastiDip,it
willnolongerwork.b. Covertheendofthepointerwhichwillbeinsertedintotheheadstickwithmasking
tape.Wethinkthatthismakesthepointerlookbetterbutthisisoptional.
c. SpraythesectionofthepointerwhichisnotcoveredbytapewithPlastiDip.
11. LetthePlastiDipdryandthenremovethetape.Belowarepicturesofthefinishedproductin
theheadstick.AlsotherearepicturesofitbeingusedonaniPodTouch2Gandyoucanseethattheuserisswitchingpagesonthehomescreentoseemoreicons.