1 Lub hauv paus ntsiab lus ntawm kev tshuaj ntsuam kov Qhov kev ua haujlwm ntawm ib qho screen kov feem ntau yog tsim los ntawm peb qhov chaw, ob lub pob tshab tiv thaiv cov khaubncaws sab nraud povtseg, ib txheej cais ntawm ob lub conductors, thiab electrodes. Cov txheej txheem resistive yog ua los ntawm cov khoom siv tiv thaiv, xws li indium tin oxide (ITO) coated rau ntawm lub substrate, lub substrate sab sauv yog ua los ntawm yas, thiab lub substrate yog ua los ntawm iav. Cov txheej txheem cais tawm yog cov khoom siv ua kua nplaum, xws li polyester zaj duab xis. Lub electrode yog ua los ntawm cov ntaub ntawv uas zoo heev conductivity (xws li nyiaj hmoov number case), thiab nws conductivity yog hais txog 1000 zaus ntawm ITO.
Thaum lub vijtsam kov ua haujlwm, cov khaubncaws sab nraud povtseg sab saud thiab qis dua yog sib npaug rau qhov kev sib txuas. Thaum ib qho hluav taws xob raug siv rau ib txheej ntawm electrodes, qhov hluav taws xob gradient yuav tsim nyob rau hauv lub network. Yog tias muaj ib qho kev quab yuam sab nraud uas ua rau cov khaubncaws sab nraud povtseg sab sauv thiab sab qis sib cuag ntawm ib qho chaw, qhov voltage ntawm qhov chaw tiv tauj tuaj yeem ntsuas ntawm lwm txheej uas tsis muaj qhov hluav taws xob siv rau cov electrode, kom cov kev sib txuas ntawm qhov chaw sib cuag tau. paub. Piv txwv li, yog hais tias ib tug voltage yog siv rau sab saum toj electrode (X ntxiv, X-), ib tug voltage gradient yog tsim nyob rau hauv lub sab saum toj conductor txheej. Thaum lub zog sab nraud ua rau cov khaubncaws sab nraud povtseg sab sauv thiab sab qis ntawm ib qho chaw, qhov hluav taws xob ntawm qhov chaw sib tiv tauj tuaj yeem ntsuas rau hauv qab txheej, Thiab tom qab ntawd raws li qhov kev sib raug zoo ntawm qhov hluav taws xob thiab cov hluav taws xob (X ntxiv), X coordinate ntawm qhov chaw paub. Tom qab ntawd, hloov qhov hluav taws xob mus rau hauv qab electrode (Y ntxiv rau , Y-), thiab ntsuas qhov hluav taws xob ntawm qhov chaw sib cuag ntawm txheej sab saum toj kom paub qhov Y ua haujlwm.
2 Kev ua tiav ntawm kev tswj ntawm lub vijtsam kov Hauv ntau daim ntawv thov PDA, lub vijtsam kov tau siv los ua cov khoom siv nkag, thiab muaj cov chips tshwj xeeb rau kev tswj ntawm lub vijtsam kov. Obviously, tus tswj nti ntawm lub vijtsam kov yuav tsum ua kom tiav ob yam: ib qho yog ua kom tiav qhov hloov ntawm qhov hluav taws xob electrode; lwm qhov yog los sau cov nqi hluav taws xob ntawm qhov chaw sib cuag (ie A / D). Hauv ntau lub tshuab embedded, CPU muab tshwj xeeb Lub module txhawb cov tswv yim ntawm LCD thiab kov npo, ua rau lub interface yooj yim heev. Piv txwv li, MOTOROLA's MC68VZ328 (hu ua Dragon Ball) muab cov pins tshwj xeeb los txhawb 8-ntsis thiab 4-ntsis kua siv lead ua kua, thiab kev txhawb nqa rau cov ntxaij vab tshaus kov kuj yooj yim ua tiav los ntawm SPI2 nrog kev pab ntawm ADS7843.
