TimHieuManHinhLCD

7/31/2019 TimHieuManHinhLCD

1/17

Nhim v ca mn hnh l ti to li hnh nh. ti to li hnh nh, phng php phbin nht hin nay l hin th hnh nh da vo bn ma trn im nh. Theo phngphp ny, mt khung hnh s c chia ra lm v s cc im nh nh. Cc im nh cdng hnh vung, c kch thc rt nh. Kch thc thc ca mt im nh l:0.01x0.01 (cm). Tuy nhin kch thc thc ny phn ln ch c ngha l thuyt, v hu

nh chng ta t khi quan st c cc im nh ti kch thc thc ca chng, mt phndo chng qu b, mt phn do kch thc quan st ca im nh ph thuc vo phngii: vi cng mt din tch hin th, phn gii (s lng im nh) cng ln th kchthc quan st c ca chng cng b. Kch thc ca mt khung hnh c cho bi slng im nh theo chiu ngang v s lng im nh theo chiu dc. V d kch thckhung hnh 1600x1200 (pixel) c ngha khung hnh s c hin b bi 1600 im nhtheo chiu ngang v 1200 im nh theo chiu dc. Nhiu ngi lm tng gi tr1600x1200 trn chnh l phn gii ca hnh nh. Thc cht, gi tr v s lng pixelch mang ngha kch thc (image dimension), cn phn gii (resolution) c chobi s lng im nh hin th trn din tch mt inch vung. phn gii cng cao,hnh nh c hin th s cng nt. phn gii t n gi tr phn gii thc khi m

mt pixel c hin th vi ng kch thc thc ca n (kch thc thc ca pixel cly sao cho mt khong cch nht nh, pixel c nhn di mt gc xp x bngnng sut phn li ca mt ngi). Nu phn gii b hn gi tr phn gii thc, mtngi s c cm gic hnh nh b sn, khng nt. Nu phn gii cao hn phn giithc, trn l thuyt, nt v chi tit ca hnh nh s tng ln, tuy nhin thc s mtngi khng cm nhn c hon ton s khc bit ny.Mt ngi cm nhn hnh nh da vo hai yu t, mu sc v sng (chi) ca hnhnh. Mn hnh mun hin th c hnh nh th cng phi ti to li c hai yu t thgic ny ca hnh nh. V mu sc, mt ngi c kh nng cm nhn hn 4 t sc mukhc nhau, trong c mt ph mu khong hn 30 triu mu c cm nhn r rt nht.Mun ti to li hnh nh chn thc, mn hnh hin th cn phi c kh nng hin th tnht l khong 16 triu mu. Bnh thng, khi mun to ra mt mu sc, ngi ta sdng k thut lc mu t nh sng trng, mi b lc mu s cho ra mt mu. Tuy nhin,vi kch thc v cng b ca im nh, vic t 16 triu b lc mu trc mt im nhl gn nh v vng. Chnh v th, hin th mu sc mt cch n gin nhng vn cungcp kh y di mu, ngi ta s dng phng php phi hp mu t cc mu c bn.H cc mu c bn phi tho mn iu kin ti to c mt ph mu rng t cc muthnh phn, v cc mu thnh phn, khi c tng hp vi cng t l phi to ra mttrong hai mu s cp l mu en (loi tr ca tt c mu sc) hoc mu trng (tng hoca tt c mu sc).V cc mu c bn, trong cc ti liu m thut c in thng cp n ba mu c bnvng, , xanh lam. Mu hp vi mu vng s to ra mu da cam, mu xanh vi to ra mu tm, mu vng vi xanh to ra xanh l. Tip tc t cc mu trn, phi hp vinhau s ra c tt c cc mu khc. Tuy nhin, h 3 mu c bn ca m thut c inngy nay t ra c nhiu nhc im trong cc ng dng k thut. Th nht, vi miln phi hp mu, mu thu c thng b xn i, gy kh khn trong vic ti to linhng mu sc ti nh xanh l m, vng chanh..., v nhc im quan trng nht, khichng ba mu c bn vng, , xanh lam vi cng ging nhau ln nhau th khng thuc mu en hon ton. Yu im ny khin cho h mu , vng, xanh lam by gich cn tn ti trong sch v, v hu nh khng c mt ng dng kthut thc t no.


2/17

Thay vo , ngy nay c hai h mu c s dng rt ph bin l h mu RGB v hmu CMYK. C s xy dng nn hai h mu c bn ny da trn nguyn l phi mupht x v phi mu hp th ca nh sng.V hai nguyn l phi mu trn, cn ni qua v c ch mt cm nhn mu. Mu sc mmt cm nhn c ph thuc vo bc sng ca nh sng chiu ti mt. Bc sng ca

nh sng chiu ti mt li ph thuc vo bn cht ngun sng. C hai loi ngun sng, l ngun sng s cp v ngun sng th cp. Ngun sng s cp l cc ngun sng c khnng t pht ra sng nh sng, cn ngun sng th cp l ngun sng pht ra nh sngbng cch phn x li nh sng t ngun sng s cp. Khi quan st mt ngun sng scp, mu sc m mt ngi quan st c chnh l mu ca nh sng m ngun sng phtra, cn khi quan st ngun sng th cp, mu sc quan st c l mu m ngun sngth cp khng c kh nng hp th t ngun sng s cp. V d: khi quan st nh sng pht ra t n led, chng ta c cm nhn mu th nh sng t n led pht ra c bcsng nm trong vng nh sng . Cn khi quan st mt tm bng mu , ta c cmnhn mu bi tm bng hp th hu ht cc bc sng khc (xanh, tm, vng...) tngun sng s cp, ch c mu l khng hp th c v truyn n mt chng ta.

Mu sc ca ngun sng s cp lun khng i, cn mu sc ca ngun sng th cp lithay i ph thuc vo mu sc ca ngun sng s cp. Chiu sng ngun sng th cpbng cc ngun sng s cp c mu khc nhau s thu c nh sng th cp khc nhau.Phi mu pht x l hnh thc phi mu s dng cho cc ngun sng s cp, cn phimu hp th l hnh thc phi mu s dng cho cc ngun sng th cp. Chng khcnhau c bn: c ch ca phi mu pht x l cng mu, cn c ch ca phi mu hp thl tr mu. C th kim chng iu ny mt cch n gin: theo nh ngha, nh sngtrng l tng ho ca v s nh sng n sc c mu sc khc nhau, c bc sng t 0.4n 0.7um. Tuy nhin, chng ta ch c th thu c nh sng trng nu chiu cc chmsng chng ln nhau (cc chm sng c pht ra t cc ngun sng s cp), c n nuchng cc mu sc ln nhau bng cch t chng ln mt t giy, tt nhin s chng baogi nhn c mu trng, m ngc li, cn ra mu en. L do l qu trnh t mu scln t giy khng phi qu trnh tng hp cc mu, m ngc li, l qu trnh loi trcc mu. Khi oi tr ht tt c cc mu th r rng ch cn mu en.


3/17

Minh ho nguyn tc phi mu pht x

Phi mu pht x c s dng trong cc thit b pht ra nh sng nh cc loi n, ccloi mn hnh. Cc nh sng c mu khc nhau, khi chiu chng ln nhau s to ra nhsng c mu sc khc. Ba mu c bn ca c ch phi mu pht x trong cc mn hnh lmu , xanh lam v xanh l (RGB). Theo hnh trn, s kt hp mu sc c v hi l:mu cng mu xanh l li ra mu vng ? Cn ch , nguyn l phi mu pht x chng khi c quan st trc tip t cc ngun sng s cp nh mn hnh, n, cn khiquan st qu trnh phi mu trn giy hoc trn mn chiu, thc cht chng ta ang quan

st mt ngun sng th cp nn hin nhin nguyn l phi mu pht x trng kh v l.Tng ho ca ba mu c bn trong phi mu pht x l mu trng.


4/17

Minh ho nguyn tc phi mu hp th

Phi mu hp th c s dng trong cc ng dng m con ngi phi quan st ccngun sng th cp, nh in bo, v tranh... Nguyn l ca phi mu hp th l tr mu.Lp vt liu s hp th tt c cc mu sc, ngoi tr mu , nn chng ta nhn cmu . Phi mu hp th da trn 4 mu c bn: CMYK: vng, xanh l, hng, en. Vl thuyt, ch cn ba mu vng, xanh l, hng l c th to ra di mu kh trung thc. Sauny, trong k thut in n, mu en c thm vo c th iu chnh mt cch chi tithn sng ti ca mu. C th thy ng dng ca h mu CMYK trong cc my in

mu: chng ch c 4 hp mc, tng ng vi 4 mu ny c th in ra tt c cc mu scca bc tranh.Nh vy, c ch phi mu trong cc mn hnh l c ch phi mu pht x, da trn bamu c bn l mu , xanh lam, xanh l. Da trn ba mu ny, mn hnh c th ti toli gn nh ton b di mu sc m mt ngi cm nhn c. l v mu sc, cn yut th hai ca hnh nh l sng, s c iu chnh bi mt n nn.

Mn hnh LCD


5/17

Do hnh nh c m ho v hin th di dng bn ma trn im nh, nn mn hnhLCD cng phi c cu to t cc im nh. Mi imnh trn mn hnh LCD s hinth mt im nh ca khung hnh. Trong mi im nh trn mn hnh LCD, c ba imnh con (subpixel), mi im nh hin th mt trong ba mu: , xanh l, xanh lam. nm c nguyn l hot ng ca mn hnh LCD, ta xt mt s khi nim sau: nh sng phn cc: theo l thuyt sng nh sng ca Huyghen, Fresnel v Maxwell,nh sng l mt loi sng in t truyn trong khng gian theo thi gian. Phng daong ca sng nh sng l phng dao ng ca t trng v in trng (vung gc vinhau). Dc theo phng truyn sng, phng dao ng ca nh sng c th lch nhaumt gc tu . Xt tng qut, nh sng bnh thng c v s phng dao ng khcnhau. nh sng phn cc l nh sng ch c mt phng dao ng duy nht, gi l

phng phn cc. Knh lc phn cc: l loi vt liu ch cho nh sng phn cc i qua. Lp vt liu phncc c mt phng c bit gi l quang trc phn cc. nh sng c phng dao ngtrng vi quang trc phn cc s truyn ton b qua knh lc phn cc. nh sng cphng dao ng vung gc vi quang trc phn cc s b chn li. nh sng c phngdao ng hp vi quang trc phn cc mt gc 0


6/17

Cc lp cu to mn hnh LCD

Quay tr li cu to mn hnh tinh th lng. Mn hnh tinh th lng c cu to bi cc

lp xp chng ln nhau. Lp di cng l n nn, c tc dng cung cp nh sng nn(nh sng trng). n nn dng trong cc mn hnh thng thng, c sng di1000cd/m2 thng l n hunh quang. i vi cc mn hnh cng cng, t ngoi tri,cn sng cao th c th s dng n nn xenon. n nn xenon v mt cu to khging vi n pha bi-xenon s dng trn cc xe hi cao cp. n xenon khng s dngdy tc nng sng nh n Vonfram hay n halogen, m s dng s pht sng binguyn t b kch thch, theo nh lut quang in v mu nguyn t Bo. Bn trong nxenon l hai bn in cc, t trong kh tr xenon trong mt bnh thu tinh thch anh.


7/17

Khi ng ngun, cp cho hai in cc mt in p rt ln, c 25 000V. in p ny vtngng in p nh thng ca xenon v gy ra hin tng phng in gia hai in cc.Tia la in s kch thch cc nguyn t xenon ln mc nng lng cao, sau chng st ng nhy xung mc nng lng thp v pht ra nh sng theo nh lut bc x int. in p cung cp cho n xenon phi rt ln, th nht vt qua ngng in p

nh thng sinh ratia

la in, th hai kch thch cc nguyn t kh tr ln mcnng lng cao nh sng do chng pht ra khi quay tr li mc nng lng thp cbc sng ngn.Lp th hai l lp knh lc phn cc c quang trc phn cc dc, k n l mt lp tinhth lng c kp cht gia hai tm thu tinh mng, tip theo l lp knh lc phn cc cquang trc phn cc ngang. Mt trong ca hai tm thu tinh kp tinh th lng c ph mtlp cc in cc trong sut. Ta xt nguyn l hot ng ca mn hnh LCD vi mt imnh con: nh sng i ra t n nn l nh sng trng, c v s phng phn cc. Sau khitruyn qua knh lc phn cc th nht, ch cn li nh sng c phng phn cc dc.nh sng phn cc ny tip tc truyn qua lp tinh th lng. Nu gia hai u lp tinhth lng khng c t mt in p, cc phn t tinh th lng s trng thi t do, nh

sng truyn qua s khng b thay i phng phnc

c. nh sng c phng phnc

cdc truyn ti lp knh lc th hai c quang trc phn cc ngang s b chn li hon ton.Lc ny, im nh trng thi tt.

Cu to mt im nh con

Nu t mt in p gia hai u lp tinh th lng, cc phn t s lin kt v xon li vinhau. nh sng truyn qua lp tinh th lng c t in p s b thay i phng phncc. nh sng sau khi b thay i phng phn cc bi lp tinh th lng truyn n knhlc phn cc th hai v truyn qua c mt phn. Lc ny, im nh c bt sng.Cng sng ca im nh ph thuc vo lng nh sng truyn qua knh lc phn ccth hai. Lng nh sng ny li ph thuc vo gc gia phng phn cc v quang trcphn cc. Gc ny li ph thuc vo xon ca cc phn t tinh th lng. xon cacc phn t tinh th lng ph thuc vo in p t vo hai u tinh th lng. Nh vy,


8/17

c th iu chnh cng sng ti mt im nh bng cch iu chnh in p t vohai u lp tinh th lng. Trc mi im nh con c mt knh lc mu, cho nh sng ramu , xanh l v xanh lam.Vi mt im nh, tu thuc vo cng nh sng tngi ca ba im nh con, da vo nguyn tc phi mu pht x, im nh s c mt munht nh. Khi mun thay i mu sc ca mt im nh, ta thay i cng sng t i

ca ba im nh con so vi nhau. Mun thay i sng t i ny, phi thay i sngca tng im nh con, bng cch thay i in p t ln hai u lp tinh th lng. Mtnhc im ca mn hnh tinh th lng, chnh l tn ti mt khong thi gian mtim nh chuyn t mu ny sang mu khc (thi gian p ng response time). Nuthi gian p ng qu cao c th gy nn hin tng bng ma vi mt s cnh c tc thay i khung hnh ln. Khong thi gian ny sinh ra do sau khi in p t ln hai ulp tinh th lng oc thay i, tinh th lng phi mt mt khong thi gian mi c thchuyn t trng thi xon ng vi in p c sang trng thi xon ng vi in p mi.Thng qua vic ti to li mu sc ca tng im nh , chng ta c th ti to li ton bhnh nh.

Mn hnh Plasma


9/17


10/17

Plasma: Plasma l mt trong cc pha (trng thi) ca vt cht. trng thi plasma, vtcht b ion ho rt mnh, phn ln cc phn t hoc nguyn t ch cn li ht nhn, ccelectron chuyn ng tng i t do gia cc ht nhn. ng dng c tnh ny ca

plasma, ngi ta ch to ra mn hnh plasma. trng thi bnh thng, cc ion dng v electron chuyn ng hn lon. Vn tctng i ca chng so vi nhau khng ln. Khi t kh plasma vo gia hai in cc,in trng tc dng ln cc ht mang in s lm cho chng chuyn ng c hng: ccelectron b ht v pha cc dng, cc ion dng b ht v pha cc m. Trong qu trnhchuyn ng ngoc chiu nhau nh vy, cc ht mang in va chm vo nhau vi vn tctng i rt ln. Va chm s truyn nng lng cho cc electron lp ngoi cng canguyn t kh, lm cho cc electron ny nhy ln mc nng lng cao hn, sau mtkhong thi gian rt ngn, cc electron s t ng chuyn xung mc nng lng thphn v sinh ra mt photon nh sng theo nh lut bc x in t. Trong mn hnhplasma, ngi ta s dng kh xenon hoc kh neon. Cc cht kh ny khi b kch thch s

pht ratia

c

ctm

, khng nhn c trc tip bng mt thng, nhng c th gin tipto ra nh sng kh kin.


11/17

Cng ging nh mn hnh LCD, mn hnh Plasma cng c cu to t cc im nh, trongmi im nh cng c ba im nh con th hin ba mu , xanh l, xanh lam. Mi imnh l mt bung kn, trong c cha cht kh xenon hoc neon. Ti mt trc cabung c ph lp pht pho. Ti hai u bung kh cng c hai in cc. Khi c in p

c t vo hai inc

c, cht kh bn trong bung kn s b ion ho, cc nguyn t bkch thch v pht ra tiacctm. Tiacctm ny p vo lp pht pho ph trn mttrc ca bung kn s kch thch cht pht pho, lm cho chng pht sng. nh sng phtra s i qua lp knh lc mu t trc mi bung kn v cho ra mt trong ba mu cbn:, xanh l, xanh lam. Phi hp ca ba nh sng ny t ba im nh con trong mi imanh s cho ra mu sc ca im nh. Nhc im ch yu ca mn hnh Plasma so vimn hnh LCD l chng khng hin th c mt phn gii cao nh mn hnh LCD ccng kch thc. iu ny do trong mn hnh LCD, mi im nh con ch cn mt lptinh th lng kh b cng c th thay i phng phn cc ca nh sng mt cch ddng, t to iu kin ch to cc im nh vi kch thc b, to nn mt s lngln im nh trn mt n v din tch ( phn gii cao). Cn vi mn hnh Plasma, mi

im nh con thc cht l mt bung kn cha kh. Th tch ca lng kh cha trong mtbung kn ny phi t mt gi tr nht nh c th pht ra bc x t ngoi mnhkhi b kch thch ln trng thi plasma. Chnh v th, kch thc mt im nh ca mnhnh Plasma kh ln so vi mt im nh ca mn hnh LCD, dn n vic vi cng mtdin tch hin th, s lng im nh ca mn hnh Plasma t hn LCD, ng ngha vi phn gii thp hn.

Mn hnh th h mi: LED display v Laser TV

Nu nh khong vi nm trc y, mn hnh tinh th lng v mn hnh Plasma c coil hai nh dng mn hnh th h mi, thay th cho mn hnh CRT qu c k. So vimn hnh CRT, mn hnh tinh th lng v plasma c nhng u im vt tri: kch thcnh gn, kiu dng n tng, thit k tm phng, v c th ch to c nhng mn hnhvi kch thc khng l. Mn hnh tinh th lng, plasma, kt hp vi cng ngh truynhnh nt cao HDTV ang m ra mt k nguyn mi trong lnh vc nghe nhn, gii tr.Nhng, khng dng li , trong khi mn hnh tinh th lng v plasma ang tng bcchim lnh th trng, th tin tc v nhng th h mn hnh mi, vi u im vt trihn xut hin. Mn hnh LED v Laser ang c coi l hai nh dng mn hnh thh mi, sau k nguyn LCD v Plasma.Chim u th so vi mn hnh CRT truyn thng bi nhiu u im, nhng mn hnhLCD v Plasma cng c nhng nhc im khng th chi ci. Thi gian p ng, gcnhn v tng phn lun l im yu cht ngi ca mn hnh LCD trong bt c cuccnh tranh no vi nhng loi mn hnh khc. Mc d cng ngh sn xut tm panel mnhnh ngy cng pht trin, nhng do c tnh k thut ca mn hnh LCD, s khng cmt ci tin no c th xo b hon ton nhng nhc im ca loi mn hnh ny. Vimn hnh plasma, phn gii, kh khn khi sn xut nhng mn hnh kch thc b, githnh cao l nhng nhc im ln. Mt cch tng qut, ti mng ho cao cp, mnhnh tinh th lng v plasma vn cha th cung cp mt cht lng hnh nh, chn


12/17

thc mu sc nh nhng mn hnh CRT truyn thng.nh vo nhng im yu ca, mn hnh LED v Laser ra i, kt hp c u imca mn hnh tinh th lng, plasma l kch thc nh gn, kiu dng p, v ca mnhnh CRT l cht lng hnh nh tuyt ho.Nhc im ca mn hnh LCD v Plasma, bt ngun t chnh cu to ca hai loi mn

hnh ny. to ra c mu sc ti mi im nh, cn phi tng hp mu sc t baim nh con. Mu sc ca ba im nh con ny c c nh lc mu t nh sng trngpht ra t n nn. Vic lc c chnh xc ba mu xanh l, xanh lam, l khng h ddng. Rt kh ch to c nhng knh lc mu hon ho, c th lc c ton b nhsng, ch cho mt nh sng n sc i qua. Bao gi cng c mt lng nh nhng nhsng n sc c mu khc lt qua c knh lc mu. Chnh nhng nh sng lt quangoi mong mun ny khin cho mu sc ca mi im nh con khng t chnh xctuyt i, dn n vic hin th mu sc ti im nh cng khng chnh xc. Hn na,nhc im ny cn khin ph mu m mn hnh LCD cng vi Plasma c kh nng tito l khng ln. Mt mn hnh LCD vi panel TN ch c kh nng hin th thc 262 000mu sc, ngay c vi panel PVA cao cp, cng ch hin th c 16.7 triu mu. So vi

ph mu m mt ngi cm nhn c, kh nng hin th mu sc ca mn hnh LCD vPlasma ch t 35-40%.Hai loi mn hnh th h mi, LED v Laser, v cu to chung cng tng t nh mnhnh LCD v Plasma, bao gm cc im nh, mi im nh cng c ba im nh con,mi im nh con hin th mt mu c bn trong h mu RGB. Tuy nhin, khc vi mnhnh tinh th lng v plasma, mn hnh LED v Laser khng s dng phng php lcnh sng t nh sng n nn cho ra nh sng n sc, m s dng phng pht phttrc tip ra nh sng c bc sng mong mun. Nh vic pht ra trc tip nh sng nsc, mi im nh con s cho ra mt mu sc chnh xc, v mu sc tng hp hin th timi im nh cng chnh xc. Mn hnh LED v Laser ang trong giai on nghin cunn hu nh rt t nh sn xut cng b cc c tnh k thut, nguyn l chi tit, nhng vc bn c th phn tch hot ng ca hai loi mn hnh trn nh sau:

Mn hnh LEDMn hnh LED, hin ang c h tr pht trin bi tp on Samsung. LED Lightemitting Diode, it pht quang, l mt loi it bn dn c kh nng pht ra nh sngkh kin, cng nh cc loi bc x hng ngoi v t ngoi. Cu to ca LED gm haikhi bn dn, mt khi loi p, v mt khi loi n ghp vi nhau. Khi t mt in pthun vo hai u LED, l trng trong khi bn dn p v electron trong khi bn dn nchuyn ng v pha nhau. Ti mt tip xc xy ra mt s tng tc gia l trng velectron. Trong qu trnh tng tc ny c th gii phng nng lng di dng nh sngkh kin hoc cc bc x in t khc nh tia hng ngoi, t ngoi. Bc sng ca nhsng kh kin pht ra ph thuc vo mc nng lng c gii phng. Mc nng lngc gii phng ph thuc vo cu trc nguyn t ca cht lm bn dn. Ngy nay, nhnghin cu v vt liu bn dn, con ngi c th ch to c nhng LED c kh nngpht ra mu sc nh mong mun, trong c ba mu c bn ca h mu RGB l xanh,xanh l, .


13/17

ng dng LED trong vic sn xut mn hnh, mi im nh s c cu to t ba LED:xanh, xanh l, . Nh iu chnh cng sng ca tng LED, c th thay i cng sng t i ca ba LED so vi nhau, nh to ra mu sc tng hp ti mi im nh.Khi mun im nh tt, ch cn tt ton b 3 LED l c th thu c mu en tuyt i,khng gp phi hin tng mu en khng chn thc do l sng t n nn nh vi mnhnh LCD.

Mn hnh LaserMn hnh Laser ang c coi l cng ngh mn hnh th h mi nhiu trin vng nht,

c h tr pht trin bi Mitsubishi. Laser l vit tt ca cm: Light Amplification byStimulated Emission of Radiation, khuch i nh sng bng cc pht x kch thch. nhsng laser pht ra cng da trn nguyn l bc x in t, tuy nhin c nhiu tnh chtc bit so vi nh sng thng thng. nh sng laser c cng mnh l laser cto thnh t cht rn. Mt cht rn thch hp, khi nhn c kch thch t bn ngoi, ccelectron bn trong s nhy ln mc nng lng cao hn, sau li nhanh chng chuynv mc nng lng thp hn v gii phng mt photon nh sng. Photon ny bay ra,chuyn ng trong lng khi cht rn, li va chm vi nhng nguyn t khc, kch thchelectron ca nguyn t ny ln trng thi cao hn, sau khi nhy xung trng thi thp litip tc pht ra mt photon khc. C nh vy to ra mt phn ng dy chuyn, cng ngycng gii phng ra nhiu photon. Ti mt u ca khi cht rn c gn mt gng bnm. Photon gp gng ny s i ra ngoi, to thnh tia Laser. Cc photon ca tia laser,do c cng tn s, cng pha, li chuyn ng song song vi nhau nn tia laser c nnglng rt ln, li c tp trung trong mt din tch nh. Mt c im quan trng catia laser, l cc photon ca n sinh ra t phn ng dy chuyn, nn nng lng ca ccphoton ging nhau tuyt i, dn n bc sng ca tia laser l ng nht tuyt i.


14/17

Laser heli-neon

Mt mn hnh laser, yu cu phi c ba tia laser vi ba mu sc xanh, xanh l, . Hinnay, mi ch c tia laser (cn gi l laser hng ngc) l ph bin v c kh nng ng

dng trong sn xut mn hnh, cn laser xanh v xanh l, do c nng lng cao hn nngn nh khng th to c trong iu kin hot ng ca mt mn hnh. Thay vo ,phi s dng mt qu trnh bin i tn s thu c laser c tn s cao hn tn s catia laser gc. Qu trnh ny gi l Second Harmonic Generation, li dng s tng tcca cc photon vi vt liu phi tuyn c bit kt hp nng lng vo mt photonmi, c nng lng gp i photon ban u, hay c bc sng nh bng mt na. SecondHarmonic Generationi c tm ra vo nm 1961, mt thi gian sau khi cc nh khoahc tm c phng php to ra tia laser bng hng ngc. Nh phng php ny, c


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th to ra c tia laser xanh v xanh l.Mn hnh laser, vi nguyn l hot ng da vo vic pht ra cc tia laser thay cho vicdng n cng cao (HID: high intensity discharge) trong cc mn hnh projector, cnhiu u im so vi cc loi mn hnh hin nay nh c kh nng ti to li mt ph murt rng vi chnh xc mu sc cao (c th t n hn 90% ph mu m mt ngi c

th cm nhn), tiu th t nng lng hn mn hnh LCD hay Plasma, kch thc gnnh, tui th lu (c th ln n hn 50000 gi). Mn hnh Laser ang c nhanh chnghon thin trong vic nghin cu, c kh nng s ra mt vo cui nm 2007, v dn phbin vo na sau nm 2008 v u 2009. Theo d on, mt khi a vo sn xut quym ln, gi thnh ca mn hnh Laser s r hn rt nhiu so vi gi mn hnh LCD vPlasma hin ti, c th ch bng mt na

Mn hnh SED


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Mu trng by th nghim mn hnh SED nm 2004

Mn hnh SED, mt thi gian tng c coi l cng ngh mn hnh th h mi trinvng nht, so vi cc cng ngh khc nh mn hnh Laser, mn hnh OLED... Tuy nhin,t sau nm 2004, vi v rc ri gia nano-proprietary (hng pht minh ra cng nghSED) v Canon (hng mua bn nguyn sn xut mn hnh SED) do Canon t chia scng ngh vi Toshiba, cc hot ng nghin cu v a vo sn xut mn hnh SEDchm hn li. Ban u, Canon d nh tung ra mu trng by chnh thc mn hnh SEDvo trin lm CES 2006 v sn xut i tr vo cui nm 2006, u nm 2007. Sau khoch ny b hu b. Vic cng b mn hnh SED c di sang trin lm CES 2007.Tuy nhin, mt nm sau, thm mt ln na, k hoch cng b mn hnh SED b tr hon,rt ng tic khi m cng ngh mn hnh v truyn hnh nt cao chnh l tiu imnng nht ca hi ch CES 2007. Mn hnh SED nh mt v th l cng ngh mn hnh

th h mi trin vng nht vo mn hnh Laser. Nguyn nhn ch yu l gi ca mnhnh SED khi sn xut hng lot s khng th cnh tranh c trn th trng, sau cn stgim gi chng mt hai loi mn hnh LCD v Plasma.

Mn hnh SED: Surface-conduction electron-emitter display: mn hnh pht x in tdn b mt. Cng ngh SED thc cht c nghin cu t rt lu, vo nm 1986.Ngay sau khi mn hnh CRT tr nn ph bin, gii khoa hc nhn ra mt s im yuca loi mn hnh ny, trong r rt nht l tn s qut qu thp vi mt s sn phmc kch thc khung hnh ln. Mt tng ban u c a ra, l s dng nhiusng phng in t thay cho mt sng phng in t ci thin tn s qut. chnh l tng bt ngun cho vic nghin cu cng ngh mn hnh SED, mt ci tin ln t mnhnh CRT.

Cu to c bn ca mn hnh CRT bao gm mt sng phng in t, mt h thng to ttrng bin i qu o electron, v mt mn hunh quang. ng phng in t datheo hiu ng pht x nhit electron. Khi cung cp nng lng cho mu kim loi didng nhit, cc electron s c truyn nng lng bt ra khi lin kt mng tinh thkim loi. Cc electron ny sau khi bt ra c tng tc bi mt in trng. Sau khi ctng tc bi in trng, electron c qu o thng hng v pha mn hunh quang.Trc khi p vo mn hunh quang, electron s phi bay qua mt vng t trng cto bi hai cun dy, mt cun to t trng ngang v mt cun to t trng dc. Tutheo cng ca hai t trng ny, qu o ca electron trong t trng s b lch i vp vo mn hunh quang ti mt im c nh trc. To ca im ny trn mnhnh c th c iu khin bi vic iu chnh cng dng in trong hai ng dy,qua iu chnh cng t trng tc dng ln electron. Electron p vo mn hunhquang (thng l ZnS) s khin im pht sng. to ra ba mu c bn trong h muRGB, ngi ta s dng ba sng phng in t ring, mi sng tng ng vi mt mu.

Cng ngh mn hnh SED, v c bn kh ging vi mn hnh CRT, cng da vo s pht


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sng ca cht hunh quang khi b electron p vo. Tuy nhin, mn hnh SED c mt citin vt bc so vi mn hnh CRT, l thay v s dng mt sng phng in t iukhin s pht sng ca ton b im nh, mn hnh SED s dng ring mt sng phngin t cho tng im nh. Vi mn hnh CRT, c th iu khin mt chm tiaelectron qut khp chiu ngang v chiu dc mn hnh, yu cu u tin l qu o ca

chmtia

electron trong t trng phi di, tng ng vi ln ca mn hnh. iuny gy ra nhc im ca mn hnh CRT l chiu dy qu ln. Nhc im th hai camn hnh CRT, l tn s qut. Do ch vi mt chm tia electron, li phi qut sutton b cc im nh trn mn hnh hin th mt khung hnh, nn thi gian hin thmt khung hnh s cng ln khi s im nh cng ln. iu ny gy tr ngi cho vic snxut cc mn hnh c kch thc ln. Mt nhc im na ca mn CRT l do chm tiaelectron phi qut xung quanh mt tm, nn b mt mn hnh l b mt cong ( l hitrc, cn gi y th c mn CRT phng). Bng vic s dng mt sng phng in tcho mt im nh ring bit, mn hnh SED khc phc hon ton ba nhc im nitrn ca mn hnh CRT. Do mi im nh c mt sng phng in t ring, nn chmelectron sau khi c tng tc bi in trng s ti p thng vo mn hunh quang m

khng cn bay qua vng t trng, nn b dy ca mn hnh SED rt b, ch ngang ngavi mn hnh LCD v Plasma. Mi im nh c iu khin c lp bi mt sngphng nn ton b im nh trn khung hnh s hin th cng mt lc, tn s hin th sln hn nhiu so vi tn s qut ca mn hnh CRT. V cui cng, khng h c bt cmt qu trnh "qut" no vi mn hnh SED, nn hin nhin b mt mn hnh s l b mtphng. Nh vy, nh da trn cng ngh truyn thng ca mn hnh CRT nn mn hnhSED s c cht lng hnh nh ngang nga mn hnh CRT, tuy nhin c kch thc mnhnh ln hn, phn gii cao hn, v nh gn hn.

Bc no c c n y l cng kin nhn lm ri y .Mo tui bi phc .H...a thi.b sung kin thc.thy hay post ln cho ngi thch tmhiu cng ngh th c .

Ph mi tay qu

TimHieuManHinhLCD

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