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ID:36257817
大小:742.77 KB
页数:17页
时间:2019-05-07
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1、CHAPTER5InputMouseInsideaMouseThemaingoalofanymouseistotranslatethemotionofyourhandintosignalsthatthecomputercanuse.Almostallmicetodaydothetranslationusingfivecomponents:Aballinsidethemousetouchesthedesktopandrollswhenthemousemoves.Theundersideofthemouse'slogicboard:Theexposed
2、portionoftheballtouchesthedesktopTworollersinsidethemousetouchtheball.OneoftherollersisorientedsothatitdetectsmotionintheXdirection,andtheotherisoriented90degreestothefirstrollersoitdetectsmotionintheYdirection.Whentheballrotates,oneorbothoftheserollersrotateaswell.Thefollowing
3、imageshowsthetwowhiterollersonthismouse:TherollersthattouchtheballanddetectXandYmotionTherollerseachconnecttoashaft,andtheshaftspinsadiskwithholesinit.Whenarollerrolls,itsshaftanddiskspin.Thefollowingimageshowsthedisk:typicalopticalencodingdisk:Thisdiskhas36holesarounditsoutere
4、dge.OneithersideofthediskthereisaninfraredLEDandaninfraredsensor.TheholesinthediskbreakthebeamoflightcomingfromtheLEDsothattheinfraredsensorseespulsesoflight.Therateofthepulsingisdirectlyrelatedtothespeedofthemouseandthedistanceittravels.closeupofoneoftheopticalencodersthattrac
5、kmousemotion:ThereisaninfraredLED(clear)ononesideofthediskandaninfraredsensor(red)ontheother.Anon-boardprocessorchipreadsthepulsesfromtheinfraredsensorsandturnsthemintobinarydatathatthecomputercanunderstand.Thechipsendsthebinarydatatothecomputerthroughthemouse'scord.Thelogicsec
6、tionofamouseisdominatedbyanencoderchip,asmallprocessorthatreadsthepulsescomingfromtheinfraredsensorsandturnsthemintobytessenttothecomputer.Youcanalsoseethetwobuttonsthatdetectclicks(oneithersideofthewireconnector).Inthisoptomechanicalarrangement,thediskmovesmechanically,andanop
7、ticalsystemcountspulsesoflight.Onthismouse,theballis21mmindiameter.Therolleris7mmindiameter.Theencodingdiskhas36holes.Soifthemousemoves25.4mm(1inch),theencoderchipdetects41pulsesoflight.YoumighthavenoticedthateachencoderdiskhastwoinfraredLEDsandtwoinfraredsensors,oneoneachsideo
8、fthedisk(sotherearefourLED/sensorpairsinsideamouse).Th
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