Ntau yam kev ua tiav thiab khaws cov ntaub ntawv tau dhau los ua ke hauv peb lub neej. Nyob rau yav dhau los, cov ntawv luam tawm tseem nyob. Cov xov xwm khaws cia niaj hnub yog dab tsi?
Optical disc: keeb kwm ntawm kev tsim
Thawj lub suab cia khoom yog tsim los ntawm Sony rov qab rau xyoo 1979. Nws yog, zoo li tam sim no, ib qho yas disk nrog lub qhov puag ncig hauv nruab nrab. Thaum xub thawj, nws tsuas yog siv rau kev sau cov ntaub ntawv suab, thiab cov ntaub ntawv raug siv rau nws nrog Pulse Code Modulation tshwj xeeb encoding txoj kev. Nws muaj nyob rau hauv qhov tseeb hais tias cov ntawv nyeem los yog suab dhau los ntawm ib tug analog-rau-digital converter thiab hloov mus rau hauv ib txheej ntawm cov khoom.
Tom qab ntawd, xyoo 1982, kev tsim cov discs loj tau pib hauv lub tebchaws Yelemes. Lawv pib yuav los khaws ntau yam ntaub ntawv. Tsis ntev lawv tsoo lub rhawv tsis yog hauv khw muag khoom suab paj nruag xwb.
CD ua haujlwm li cas? Rau kev tsim cov hauv paus, 1.2 hli tuab polycarbonate phaj nrog txoj kab uas hla ntawm 120 hli yog siv, uas yog thawj zaug.npog nrog ib txheej nyias ntawm cov hlau (kub, txhuas, nyiaj, thiab lwm yam), thiab tom qab ntawd cov kua roj vanish. Nws yog nyob rau ntawm cov hlau uas cov ntaub ntawv yog siv nyob rau hauv daim ntawv ntawm pits (recesses) extruded raws ib tug kauv txoj kev. Kev nyeem cov ntaub ntawv kaw rau ntawm qhov muag pom tshwm sim siv lub teeb laser nrog lub wavelength ntawm 780 nm. Nws qhia tawm ntawm qhov chaw ntawm lub phaj, hloov theem thiab siv, tsoo lub pits. Av feem ntau hu ua qhov khoob ntawm qhov pits. Lub suab ntawm ib txoj kab hauv ib lub kauv yog li 1.6 microns.
Hom kho qhov muag discs
Muaj ntau hom CDs: Compact Disc (CD), Digital Versatile Disc (DVD), Blu-ray Disc (BD). Tag nrho lawv muaj peev xwm sib txawv rau kev sau cov ntaub ntawv. Piv txwv li, DVDs yog tsim nyob rau hauv lub peev xwm ntawm 4.3 mus rau 15.9 GB, thaum CDs tsuas muaj txog li 900 MB.
Disks kuj txawv los ntawm tus naj npawb ntawm cov kaw: ib leeg thiab ntau yam. Nyob rau hauv xws li cov cab kuj, cov qauv nyem ntawm pits yog tsim txawv. Overwriting yog ua tau ua tsaug rau cov khoom siv organic, uas darkens nyob rau hauv qhov kev txiav txim ntawm lub laser thiab hloov lub reflectance. Colloquially, txheej txheem no hu ua hlawv.
Tsis tas li, cov xov xwm kho qhov muag yuav txawv ntawm cov duab. Figured compact disks (Shaped CD) feem ntau yog siv rau hauv kev ua lag luam ua tus saib xyuas cov ntaub ntawv audio - thiab video. Lawv tuaj nyob rau hauv txhua yam duab (square, nyob rau hauv daim ntawv ntawm lub dav hlau los yog lub plawv). Nws tsis pom zoo kom siv lawv hauv CD-ROM drives vim tias lawv tuaj yeem tawg ntawm kev sib hloov ceev.
CDs thiab lawv hom
kho qhov muagCD-R disc yog qhov nruab nrab cia uas nyeem nkaus xwb. Koj tuaj yeem sau cov ntaub ntawv rau nws ib zaug xwb tsis muaj cai ntxiv thiab kho. Thaum pib, lub peev xwm ntawm cov discs tsuas yog mus txog 650 MB lossis 74 feeb ntawm kev kaw suab. Tam sim no cov khoom siv tau raug tsim tawm uas tuaj yeem tuav txog 900 MB ntawm cov ntaub ntawv. Lawv qhov zoo yog tias txhua tus qauv CDs txhawb kev nyeem ntawv.
A CD-RW laser disc muaj tib lub cim xeeb, tsuas yog cov ntaub ntawv tuaj yeem sau rau nws ntau zaus (txog 1000 zaug). Rau qhov no, cov txheej txheem khoos phis tawj siv tau. Lub downside yog tias tsis yog txhua yam khoom siv tau npaj ua haujlwm nrog hom ntawv no. CD-RWs me ntsis kim dua CD-Rs.
Audio thiab video CDs tsis muaj kev tiv thaiv txhua txoj hauv kev thiab tuaj yeem luam tawm thiab ua si. Tab sis kev tshaj tawm nrog qee cov ntaub ntawv raug tiv thaiv los ntawm kev theej los ntawm StarForce thev naus laus zis.
ROM discs raug kaw hauv lub hoobkas thiab tsuas tuaj yeem rov qab cov ntaub ntawv. Nws tsis tuaj yeem hloov kho xws li xov xwm. Tab sis cov khoom siv kho qhov muag xws li RAM tuaj yeem rov sau dua txog 10 txhiab zaus thiab lawv kav ntev txog 30 xyoo. Cov discs no tau tsim nyob rau hauv cov cartridges ntxiv thiab tsis tuaj yeem nyeem tau los ntawm cov khoom siv disk.
DVD media thiab specifications
Digital Versatile Disc yog qhov nruab nrab digital ntau qhov chaw cia. Nws cov qauv yog denser thiab muaj ntau cov ntaub ntawv (txog 15 GB). Xws li ib tug optical disc zoo li ob CDs glued ua ke. Kev khaws cia thiab nyeem cov ntaub ntawv ntau yog ua tau vim yog siv lub laser liab, lub wavelength ntawm uasyog 650 nm, thiab lo ntsiab muag nrog ntau tus lej aperture. DVDs muaj ib lossis ob sab kaw, nrog rau ib lossis ob txheej ua haujlwm ntawm txhua sab. Cov ntsuas no txiav txim siab lawv lub peev xwm.
Zoo li CDs, DVDs tuaj ntau hom ntawv. DVD-R lossis DVD+R yog cov xov xwm uas tsuas yog sau rau ib zaug xwb. Cov txheej txheem kaw rau cov discs yog tsim los ntawm Pioneer hauv xyoo 1997. "Minus" thiab "plus" cov khoom siv sib txawv ntawm cov khoom siv ntawm cov txheej txheem kev cuam tshuam thiab cov cim tshwj xeeb.
DVD RW (DVD + RW, DVD-RW) optical discs muaj peev xwm rov sau dua ntau zaus. Ntxiv mus, cov xov xwm "plus" tso cai rau koj hloov pauv rau qhov chaw koj xav tau ntawm koj qhov kev txiav txim siab. Universal drives pab daws qhov teeb meem ntawm hom ntawv tsis sib xws (+RW thiab –RW).
Blu-ray Disc yog dab tsi?
hom optical disc no tuaj yeem khaws thiab sau cov ntaub ntawv digital siab. Txhawm rau rov tsim cov ntaub ntawv (txawm tias cov yeeb yaj kiab siab txhais), siv lub teeb xiav laser ntawm 405 nm, uas ua rau ob npaug ntawm kev sib tw. Cov ntaub ntawv uas nyob ze rau ib leeg yog rhiab heev rau kev puas tsuaj, yog li lub disk yuav tsum tau saib xyuas tshwj xeeb. Tsis ntev los no, kev tshaj tawm nrog cov txheej tshwj xeeb tau tsim, uas tuaj yeem so nrog daim ntaub qhuav tsis tu ncua.
Muaj Blu-duab tshav discs ntawm ib zaug thiab rov siv tau cov ntaubntawv povthawj siv, nrog rau ntau txheej discs (los ntawm 2 mus rau 4 txheej). Lub peev xwm ntawm feem ntau "layered" media ncav cuag 128 GB. Nyob rau tib lub sijhawm, nws muajstandard 12 cm diam. Ib txheej dual-txheej txheem Blu-duab tshav disc tuav txog 50 GB ntawm cov ntaub ntawv. Ib lub cuab yeej tab tom tsim kho uas ncav cuag lub peev xwm ntawm 300-400 GB, uas tuaj yeem nyeem tau los ntawm niaj hnub disk drives. Cov koob yees duab siv cov discs me me (80 mm) nrog txog li 15 GB ntawm kev nco.
Rau kev tiv thaiv daim ntawv, Blu-rays feature ROM-Mark digital watermarks thiab Mandatory Managed Copy thev naus laus zis.
Lub hom phiaj ntawm MiniDVD media
Optical media Mini DVD yog ib daim ntawv me me ntawm Digital Versatile Disc li niaj zaus. Nws yog 8 cm nyob rau hauv lub cheeb thiab yog siv nyob rau hauv cov duab thiab video koob yees duab. Ib leeg-sab disc tuav txog 1.4 GB ntawm cov ntaub ntawv, feem, ob sab ib - 2.8 GB. Hais txog hom ntawv, lawv yog MiniDVD-R (sau ib zaug) thiab MiniDVD-RW (rov ua dua).
Standard 12cm tsav tsis yog tsim los nyeem Mini DVD. Thaum siv cov disks zoo li no hauv lub laptop, yuav tsum siv lub tshuab tsav spindle. Qee zaum muaj teeb meem nrog kev nyeem cov ntaub ntawv nqa khoom. Feem ntau hauv cov xwm txheej zoo li no, lub khoos phis tawj qhia cov lus "tsis muaj tus tsav tsheb rau qhov kho qhov muag pom." Txhawm rau daws qhov teeb meem, koj yuav tsum hu rau tus kws tshaj lij programmer.
