SMARCOS HIG Paper on Designing Touch Screen Interfaces

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Text of SMARCOS HIG Paper on Designing Touch Screen Interfaces

  • 1. User Interface Design forTouch Screens
  • 2. Content1. Itsallabouttouch............................................................................................................................................. 32. Understandthetechnology............................................................................................................................43. Canttouchthis.................................................................................................................................................... 74. Makeagoodproduct.......................................................................................................................................10 4.1.Determiningthepurposeofyourtouchscreensoftware.........................................................10 4.2.Basicdesignprinciples............................................................................................................................. 145. Keepitsimple......................................................................................................................................................16 2
  • 3. Its all about touch Manypeoplethinkthattouchscreendevicesarearecentphenomenon,butinfacttheyhavebeen around for quite some time. At first, touch screens were mainly used for corporate and business applications,suchaspaymentterminalsatgasstations,cashregistersystemsatsupermarketsor controlpanelsinmeetingrooms. Therewasarelativelysmallpenetrationoftheconsumer market.Thefirsttouchscreendevicesthat weremadeavailabletoconsumerswereamongstothers-bulkyPDAsintheninetiesandportable GPSdevicesintheearly2000s.WecanallrememberthosefirstPalmPDAswithamonochrome screenthatwereconsideredtobehigh-techatthetime.Seemslikeagesago. In2007,Applesintroductionof theiPhonecausedamajor boomin touchscreendevicesfor the consumermarket.Thisnotonlymanifesteditself throughanabundanceof touchscreenmobile phones,butalsoencouragedothersectorstodeveloptouchscreenproducts. Companies started embracing the touch screen market potential by building mobile websites, specificapplicationsforiPhoneandAndroidandevenreleasingtheirowntouchscreenproducts. For example, some car manufacturers switched from hardware controls to full touch screen for built-inradioandnavigationsystemsandtabletPCshaveresurfacedafterfailingmiserablyafew yearspreviously. Theresnodoubtthattouchhasbecomethelatesthottrendintechnologyandeveryoneisjumping onthewagon.Ofcourse,thetrendfactorisnottheonlyreasonwhytouchscreensarebooming. The technology offers some significant advantages. For many users its the most user friendly andintuitivewayofgivinginputtoadevice.Touchscreensallowalotofflexibilitytowardsfuture evolutions of the product, whereas with typical hardware user interfaces, the functions have to bedefinedmorepreciselyfromthestart.Theuserinterfacecanalsobeconstructedinlayers,only revealingfunctionswhentheyareneeded. However, you cant forget that developing software for a touch screen device has significant implicationstowardsuserinterfacedesign. 3
  • 4. Understand the technology Before you start designing the user experience of your touch screen software, you need to ask yourself: What is the software meant for? Whenyoustartoffdevelopingatouchscreenproduct,thereareafewthingstoconsider.Firstofall, atouchscreenisnotjustatouchscreen.Thereisawiderangeoftouchscreentechnologyavailable and each one has an impact on the user interface. More than that, the choice of touch screen technologyisakeyfactorfortheuserinterfacedesign. Outofthemanytechnologiesavailable,twotypesoftouchscreensemergeasmostsuitableforuse inbothbusinessandconsumerproducts,capacitiveandresistive.Thenamesofbothtechnologies refertothewaytouchinputiscapturedandsenttothedevicescontroller. Capacitive touch screen technology As its name says, capacitive touch screens use capacitance to register input (capacitance is the abilityofabodytoholdanelectriccharge).Thehumanbodymorespecifically,theusersskin-acts asaconductor.Atouchdisturbsanelectrostaticfield,whichisusedtodeterminethelocationofthe touch.Thatlocationisthensenttothecontrollerforprocessing. Schematic representation of capacitive touch screen technology 1 4
  • 5. A capacitive touch screen has some significant advantages. This screen type offers an excellent quality of interaction. Finger touches are registered very fluently. The software reacts instantaneouslytotouchandmovementsareexecutedsmoothlyandaccurately,whichheightenstheuserexperience.Theuseofskinasaconductorisalsooneofthemaindrawbacksofcapacitivetouchscreens,e.g.a user wearing gloves cannot operate it. Furthermore, capacitive touch screens are expensive toproduceandwillinevitablyincreasetheretailpriceoreffectivecostoftheendproduct.Thisiswhycapacitivetouchscreensaremorecommoninhigh-endconsumerproducts,suchassmartphones.Resistive touch screen technologyA resistive touch screen is composed of multiple layers. Two of those layers are separated by a narrowgap.Whenthescreenispressed,thosetwolayersmakecontact,whichcausesachangeinelectricalcurrent.Thischangeis registeredasatouchandsenttothecontroller.Schematic representation of resistive touch screen technology 2Oneofthemainadvantagesofresistivetouchscreentechnologyisthepossibilitytouseanobject,suchasastylusorpen,totouchthescreen.Userscanmoreeasilymanipulatesmallobjectsintheuserinterfacebyusingthenarrowtipofastylus.Sincethescreenusespressuretoregisteratouch,theusercanperceivethisasaformoftactilefeedback,likeyougetwhenpressinganactualbuttononthemouseorakeyboardkey. 5
  • 6. Compared tocapacitive touchscreens,resistive touchscreensarecheaper toproduceand-thus-theobviouschoiceforbudget-friendlyproducts,suchasportableGPSdevices.However,thetouchinteraction on a resistive touch screen is a lot less fluent. Because the user has to press downon the screen, they perceive the movements to be less smooth or accurate. Also, implementingmulti-touchgesturesrequiresmoreadvancedtechnologies,whicharemoreexpensive.Note: Surely, you have noticed that the technical description above is a high-level overview ofcapacitive and resistive touchscreen technology and is by no means exhaustive.HardwareNotonlythetypeofscreenthatyouareusingisimportantfordeterminingyouruserinterface,buttherestofthehardwareisequallydecisive.Considerthefollowinghardwareoptions: Adevicewithafulltouchscreenandanabsoluteminimumofhardwarekeys(e.g.ApplesiPad). Thismeansthatalltheinteractionwiththedeviceandinputhavetobeaccomplishedusingthe touchscreen.Evidently,theuserinterfacemustbeadaptedtothat. Adevicewithatouchscreen,combinedwithhardwarebuttons(e.g.Saabsbuilt-inradioand navigationsystem).Theuserinterfacehastobeclearonwhichtaskscanbeperformedusing thedevicestouchscreenandwhichtaskrequirethehardwarebuttons. A device with a touch screen, combined with a fully functional keyboard (e.g. most ATMs). This combination is probably the most intricate one, as navigation and interaction has to be supportedbyboththetouchscreenandthekeyboard.Itisclearthat,whateverchoiceyoumakeconcerningtouchscreentechnologyandhardware,theuser interface of the devices software is affected. Youneedtofindtheproperwayofnavigating,providingfeedback,inputtingtext,makingselections,etc 6
  • 7. Cant touch this 3 Designingatouchscreendevice,whetheritisforconsumerorbusinessuse,isnever a quick job. Whenatouchscreenproductfails,thefailureisoftenlinkedtosomecommonlymademistakes. Theseareoftenamixtureofshortcomingsin thedesignof thehardwareand theuserinterface design. Whatfollowsaresomekeymistakeswhendevelopingtouchscreenproducts: Simply porting desktop software Desktopsoftwareoranykindofnon-touchscreens