Bai Giang Ki Thuat Chieu Sang Do Thi

TRNG I HC KIN TRC NNG

Khoa K thut h tng th v Qun l xy dng

Nguyn Mnh H

BI GING K THUT CHIU SNG TH

Nng thng 03-2009

Bi ging K thut chiu sng th

LI CM N

Bi ging K thut chiu sng th c bin son lm ti liu ging dy chnh thc cho

ngnh K thut h tng th, Trng i hc kin trc Nng. Trong qu trnh bin son, tc gi nhn c s ng h, ng vin cng nh kin ng gp v s gip ca cc t chc, c nhn sau y:

- Cc thy gio, c gio trong Khoa K thut h tng th v Qun l xy dng. - Phng Qun l in, S Cng Thng thnh ph Nng. - Cng ty Qun l vn hnh in chiu sng cng cng Nng - Cng ty Schrder Vit Nam. - Gia nh v bn b ng nghip. Tc gi xin chn thnh cm n s gip qu bu . Do bin son ln u vi thi gian, kinh nghim c hn, chc chn tp bi ging ny cn

c nhiu thiu st, tc gi rt mong nhn c cc kin ng gp ca cc ng nghip, sinh vin v bn c quan tm n lnh vc chiu sng tin ti bin son thnh gio trnh hon chnh phc v cng tc ging dy, hc tp cng nh cng tc ca sinh vin sau khi ra trng.

Cc kin ng gp xin gi v a ch: Vn phng Khoa K thut h tng th v Qun l xy dng Tng 4, Trng i hc Kin trc Nng S 566 Ni Thnh, qun Hi Chu, thnh ph Nng. Email : [email protected] Tc gi

Nguyn Mnh H - Trng i hc Kin trc Nng 1


MC LC

M U................................................................................................................................................ 5 LCH S CHIU SNG NHN TO V VAI TR CA N ......................................................... 5 CHNG 1............................................................................................................................................ 7 KHI NIM C BN V CC I LNG O NH SNG ....................................................... 7

1.1. Bn cht ca nh sng ................................................................................................................. 7 1. Bn cht sng - ht ca nh sng: .............................................................................................. 7 2. Ngun sng t nhin v quang ph lin tc ............................................................................... 7 3. Ngun sng nhn to v quang ph vch................................................................................... 8

1.2. Mt s hin tng pht sng v phm vi ng dng trong chiu sng nhn to: ......................... 9 1. Hin tng pht sng do nung nng: ......................................................................................... 9 2. Hin tng pht sng do phng in: ........................................................................................ 9 3. Hin tng pht sng hunh quang.......................................................................................... 11 4. Hin tng pht sng ln quang............................................................................................... 11 5. Hin tng pht sng th cp:.................................................................................................. 12

1.3. Cc i lng c bn o nh sng............................................................................................. 12 1. Gc khi (cn gi l gc c, gc nhn) .................................................................................. 12 2. Thng lng nng lng ca bc x nh sng nhn thy......................................................... 14 3. Quang thng ............................................................................................................................. 15 4. Quang hiu ............................................................................................................................... 16 5. Cng sng.......................................................................................................................... 16 6. ri........................................................................................................................................ 17 7. sng (cn gi l trng): ................................................................................................. 18 8. chi ..................................................................................................................................... 19 9. Nhit mu: ........................................................................................................................... 19 10. hon mu (cn gi l ch s th hin mu):...................................................................... 20

1.4. Cc nh lut quang hc v ng dng trong k thut chiu sng :............................................ 21 1. S phn x:............................................................................................................................... 21 2. S truyn x : ........................................................................................................................... 22 3. S khc x:............................................................................................................................... 23 4. S che chn: ............................................................................................................................. 24 5. S hp th: ............................................................................................................................... 24 6. nh lut Lambert v s khuych tn u :.............................................................................. 25

CHNG 2.......................................................................................................................................... 27 MT NGI V S CM TH NH SNG................................................................................. 27

2.1 Cu to mt ngi ...................................................................................................................... 27 1. Hin tng th gic:.................................................................................................................. 27 2. Hin tng iu tit ca mt: ................................................................................................... 27 3. Vng mc: ................................................................................................................................ 27 4. Khi nim con mt quc t: .................................................................................................. 27

2.2 S gii m hnh nh:................................................................................................................... 28 2.3 Qu trnh thch nghi : ................................................................................................................. 28 2.4 Cm gic chiu su ca vt cn nhn: ........................................................................................ 28 2.5 Cc cn v cc vin ca mt :.................................................................................................... 29 2.6. Trng nhn ca mt : ............................................................................................................... 29 2.7 tng phn :.......................................................................................................................... 29 2.8 Hin tng chi la:................................................................................................................... 30

1. Khi nim: ................................................................................................................................ 30 2. Gii thch hin tng chi la :................................................................................................ 30 3. Cc ch s kim sot chi la ................................................................................................... 31

CHNG 3.......................................................................................................................................... 33 CC LOI NGUN SNG NHN TO THNG DNG .............................................................. 33

3.1 Bng n nung sng: .................................................................................................................. 33



1. Cu to ca bng n nung sng (hnh 3.1): ............................................................................ 33 2. Mt s loi bng n nung sng thng dng: .......................................................................... 34

3.2 Bng n hunh quang............................................................................................................... 35 1. c im cu to:..................................................................................................................... 35 2. Mt s bng n hunh quang thng dng .............................................................................. 37

3.3 Bng n phng in cng cao (HID) ................................................................................ 38 1. Cu to ca bng n phng in: ........................................................................................... 38 2. Mt s loi bng n phng in HID thng dng:................................................................. 39

3.4 n pht sng quang in (LED: Lighting Emitting Diode) ..................................................... 43 3.5 n cm ng (n khng in cc) ........................................................................................... 44 3.6 n Sulfua :................................................................................................................................ 44

CHNG 4.......................................................................................................................................... 46 CU TO CA B N CHIU SNG CNG CNG ................................................................. 46

4.1. Cu to chung ca mt b n chiu sng cng cng............................................................... 46 4.2. Cc b phn chnh ca b n chiu sng cng cng ............................................................... 47

1. Tm phn quang ....................................................................................................................... 47 2. Thit b mi n (tc te) v chn lu ....................................................................................... 47 3. Knh bo v .............................................................................................................................. 48 4. L ui n................................................................................................................................. 49

4.3. Cc thng s c hc ch yu ca b n chiu sng cng cng............................................... 49 1. kn (IP)................................................................................................................................ 50 2. Cp bo v c hc chng n (cn gi l chu va p ca knh n) .................................. 50 3. Din tch cn gi ...................................................................................................................... 51 4. Ch tiu lo ha knh bo v..................................................................................................... 51 5. Trng lng.............................................................................................................................. 51

4.4. Cc thng s in ch yu ca b n chiu sng cng cng................................................... 51 1. Cp cch in ........................................................................................................................... 52 2. dao ng in p................................................................................................................. 52

4.5. Cc thng s v quang hc ca b n chiu sng cng cng.................................................. 52 1. H s suy gim quang thng .................................................................................................... 52 2. H s phn quang ..................................................................................................................... 53 3. ng cong trc quang ............................................................................................................ 53 4. Hiu sut ca b n ................................................................................................................ 55 5. Cp b n................................................................................................................................ 56 6. H s s dng ca b n......................................................................................................... 57 7. Gc bo v................................................................................................................................ 58

4.6. Phn loi cc b n chiu sng cng cng: ............................................................................. 59 CHNG 5.......................................................................................................................................... 60 THIT K H THNG CHIU SNG CNG CNG..................................................................... 60

5.1. S lc v lch s cc phng php, trnh t thit k............................................................... 60 5.2. Cc tiu chun chiu sng ng giao thng............................................................................ 60 5.3. Cc nguyn tc c bn............................................................................................................... 60

1. Phng v v tr quan st ca ngi li xe ............................................................................... 61 2. chi mt ng................................................................................................................... 61 3. ng u ca chi mt ng ....................................................................................... 62 4. Hin tng chi lo trong trng nhn..................................................................................... 63 5. Hiu qu dn hng ti cc v tr c bit................................................................................ 65

5.4. Phng php t s R trong thit k chiu sng :........................................................................ 65 1. Cc thng s hnh hc b tr n.............................................................................................. 66 2. Cc phng n b tr n ......................................................................................................... 67 3. Chn cng sut v loi b n ................................................................................................. 69

5.5. Phng php chi im trong thit k chiu sng ............................................................... 70 1. chi ca mt im trn mt ng..................................................................................... 70 2. Phn loi cc lp ph mt ng ............................................................................................. 71



3. Tnh ton chi v ri im ............................................................................................. 72 4. Mng li tnh ton theo tiu chun mi CIE-140 .................................................................. 74

5.6. Thit k chiu sng ti cc im c bit trn ng giao thng ............................................. 77 1. Chiu sng ti im giao nhau ng mc ................................................................................ 77 2. Chiu sng nt giao vi ng st ........................................................................................... 79 3. Chiu sng ng cong............................................................................................................ 80 4. Chiu sng bng binh............................................................................................................... 80 5. Chiu sng ng hm............................................................................................................. 81

5.7. Thit k chiu sng vi s tr gip ca my tnh ..................................................................... 84 5.8. S dng phn mm thit k chiu sng cng cng Ulysse 2.2 ................................................. 84

1. Khi ng................................................................................................................................. 85 2. Chn phng n b tr n....................................................................................................... 86 3. Chn n v cc thng s v n ............................................................................................. 88 4. Xem kt qu v lp bo co ..................................................................................................... 90 5. Phn tch chi tit mn hnh xut kt qu ca Ulyse v2.2 ......................................................... 92

5.9. Mt s ni dung thit k khc ca h thng chiu sng ng giao thng .............................. 93 1 Thit k in :............................................................................................................................ 93 2 Thit k xy dng...................................................................................................................... 95 3 Thit k kt cu ......................................................................................................................... 95

CHNG 6.......................................................................................................................................... 97 QUN L, VN HNH H THNG CHIU SNG CNG CNG.............................................. 97

6.1. Ni dung qun l, vn hnh : .................................................................................................... 97 6.2. C cu t chc v trang thit b vn hnh................................................................................. 98 6.3. Vn tit kim in : .............................................................................................................. 98 6.4. Thc trng qun l vn hnh..................................................................................................... 99 6.5. T ng ho cng tc qun l, vn hnh h thng in chiu sng :........................................ 99

CHNG 7........................................................................................................................................ 100 THIT K CHIU SNG CNG TRNH CNG CNG TRONG TH ................................. 100

7.1. Chiu sng cng vin, vn hoa ............................................................................................. 100 1. Cc nguyn tc chung ............................................................................................................ 100 2. Ch tiu k thut v chiu sng : ............................................................................................ 100

7.2. Chiu sng cng trnh th thao ngoi tri - nhng nguyn tc chung : .................................. 102 CHNG 8........................................................................................................................................ 105 MT S VN CN NGHIN CU CA CHIU SNG TH ........................................ 105

8.1. nhim nh sng.................................................................................................................... 105 8.2. Quy hoch chiu sng ............................................................................................................. 106

PH LC........................................................................................................................................... 108 1. Bng gi tr v biu thc hm V():........................................................................................... 108 2. Cng sut v quang thng cc loi n phng in thng dng ................................................ 108 3. Bng phn loi cc lp ph mt ng :.................................................................................... 109

TI LIU THAM KHO.................................................................................................................. 113 PHN BI TP................................................................................................................................. 114



M U

LCH S CHIU SNG NHN TO V VAI TR CA N

T thi k s khai con ngi bit to ra nh sng t la, tuy nhin lc con ngi

dng la vi t cch l ngun nhit ch khng phi l ngun sng. Tri qua mt thi k di ca lch s, con ngi mi pht minh ra loi n thp sng bng cht kh. Sau khi nh ho hc ngi o K.Auer pht minh ra n mng sng ch to bng cht chu c nhit cc cao cho nh sng trng khi t chy trong ngn la cht kh th n mng sng tr nn ph bin khp cc thnh ph ln trn th gii, n ni tng nh khng th cn loi n no c th thay th c.

Tuy nhin cui th k 19 ngi ta bt u nhn thy u im khi thp sng bng in. Cho n nay ngi ta vn cha bit chnh xc ai l ngi u tin ch to ra chic n in u tin. Tuy nhin i n chic bng n hon thin nh ngy nay chc chn phi c s cng hin ca nhiu nh khoa hc, trong ngi c cng ln nht v l ngi ng k bn quyn pht minh u tin v bng n dy tc vo nm 1878 l Thomas Edison - mt nh pht minh ni ting ca M. ghi nhn cng lao v s n lc ca ng trong vic em nh sng n cho nhn loi m ngy nay ngi ta tng nh ng nh l cha ca mi loi bng n in dng si t.

m 24/12/1879 Edison mi hng trm ngi thuc mi thnh phn trong x hi thnh ph New York ti d ba tic ti nh ng nhm qung co sn phm n in do ng ch to ln u tin. Ti ba tic ny ng cho thp sng hng lot bng n tt c khu nh , xng my, phng th nghim v sn vn. Kt qu ba tic gip ng nhn c s ti tr ca chnh quyn cho n thp sng thnh ph. Cui cng, n 5 h sng ngy 04/9/1882 hng trm ngn n trn cc ph ng lot bt sng lm c mt gc thnh ph NewYork trn ngp nh sng in, nh du thi khc lch s nh sng in chinh phc bng m. y c th c xem l thi im ra i ca ngnh chiu sng th.

Ti Vit Nam trc y, chiu sng th c xy dng trn c s li n chiu sng cng cng c xy dng t thi Php thuc, ch yu dng bng n si tc. n nm 1975, nhng ngn n cao p u tin c lp t ti khu vc qung trng Ba nh v lng Ch tch H Ch Minh. Ngoi chiu sng ng ph, cc loi chiu sng khc ca th nh chiu sng cng vin, vn hoa, chiu sng cnh quan cc cng trnh kin trc vn ho, lch s, th thao, chiu sng tng i... hu nh cha c g.

Hi ngh chiu sng th ln th nht (4/1992) l mt mc khi u cho s pht trin ca ngnh chiu sng th Vit Nam. Thc trng chiu sng th lc by gi vn cn rt km, lc hu so vi cc th trong khu vc. Sau Hi ngh chiu sng th ton quc ln th hai (12/1995) t chc ti Nng, cng vi s pht trin vt bc ca nn kinh t, lnh vc chiu sng th nc ta thc s hnh thnh v pht trin. Hin nay chng ta c Hi chiu sng th Vit nam.



Vai tr ca chiu sng th: Ti cc nc pht trin, in nng dng cho chiu sng chim t 8 n 13% tng in

nng tiu th. H thng chiu sng th bao gm nhiu thnh phn khc nhau, trong c th k n chiu sng phc v giao thng, chiu sng cc c quan chc nng ca th...

Chiu sng ng ph to ra s sng ng, hp dn v trng l cho cc th v m, gp phn nng cao cht lng cuc sng cho ngi dn th, thc y s pht trin thng mi v du lch. c bit, h thng chiu sng trang tr cn to ra khng kh l hi, s khc bit v cnh quan ca cc th trong cc dp l tt v cc ngy k nim ln hoc trong thi im din ra cc hot ng chnh tr, vn ha x hi cng nh s kin quc t.

Trong iu kin thiu ht v in nng ca nc ta, c nhng lc, nhng ni chiu sng qung co b coi l ph phim, lng ph v khng hiu qu. iu ny xut pht t gc tiu th nng lng m cha nhn thc tng qut vai tr ca chiu sng th. Do cn c s nh gi chnh xc v khch quan v hiu qu m chiu sng em li khng ch v mt kinh t, m cn c trn cc bnh din vn ha - x hi. Khng ch nhn nhn nhng hiu qu trc tip trc mt, c th tnh c bng tin m cn c hiu qu gin tip v lu di m chiu sng em li trong vic qung b, thc y s pht trin ca thng mi, du lch v dch v. Ch c nh vy, h thng chiu sng th mi c th pht trin v duy tr mt cch bn vng, ng mt vai tr ngy mt xng ng trong cc cng trnh h tng k thut th.

lm c vic chng ta phi y mnh vic nghin cu, ng dng, pht trin l thuyt v chiu sng th ngy cng hon thin nhm xy dng th Vit Nam va mang phong cch hin i va gi gn c nt truyn thng.



CHNG 1 KHI NIM C BN V CC I LNG O NH SNG

1.1. Bn cht ca nh sng 1. Bn cht sng - ht ca nh sng: + nh sng nhn thy, tia cc tm, tia X, sng radio, sng truyn hnh,tt c u l

nhng dng nng lng in t c truyn trong khng gian di dng sng, cng ging nh cc bc x in t khc c c trng bi bc sng , tn s , hoc chu k T vi = 1/T hoc c = ..

+ C th chia bc sng thnh cc phm vi sau, ta nhn thy nh sng nhn thy ch l di hp t 380nm-780nm:

T 3000 m n 1000 m Sng di (LW = long wave) T 1000 m n 100 m Sng trung (MW = medium wave) T 100 m n 10 m Sng ngn (SW = Short wave) T 10 m n 0,5 m Sng v tuyn (FM) T 0,5 m n 1,0 mm Sng raa T1000 m n 0,78 m Sng hng ngoi T 780 nm n 380 nm nh sng nhn thy T 380 nm n 10 nm Tia cc tm (tia t ngoi, UV) T 100 A0 n 0,01 A0 Tia X T 0,01 A0 n 0,001 A0 Tia , tia v tr ( 1 m = 10-6 m; 1 nm = 10-9 m; 1 A0 = 10-10 m) + Theo thuyt lng t, nh sng cn mang bn cht ht (photon), c nng lng E = h=

hc / ; trong h l hng s Plank = 6,626176 10-34Js Ti sao cc vt th pht ra nh sng ? Ta phi dng thuyt lng t gii thch nh sau: + Mt photon b bin mt khi n va vo v y mt in t vng ngoi ln trng thi kch

thch cc qu o xa nhn hn s hp thu nng lng nh sng ca vt cht. + Mt photon c sinh ra khi in t t trng thi kch thch chuyn sang mt qu o

khc gn nhn hn v ti i mt nng lng m nguyn t b mt di dng tia sng m bc sng t l nghch vi nng lng c truyn i s pht ra nng lng nh sng ca vt cht.

+ Nh vy cn c vo bc sng ta c th phn bit c sng nh sng v cc dng nng lng khc trn quang ph in t.

2. Ngun sng t nhin v quang ph lin tc + nh sng nhn thy khc vi cc dng bc x in t khc kh nng lm kch hot

vng mc ca mt ngi. + Vng nh sng nhn thy c bc sng dao ng t 380nm-780nm + Th nghim chng minh: di ph ca nh sng mt tri l di quang ph lin tc c

bc sng thay i t 380nm 780nm nh hnh sau: + nh sng mt tri c coi l ngun sng chun nh gi cht lng ca ngun sng

nhn to.




+ nh sng mt tri c rt nhiu cng dng khc ngoi chiu sng : sinh ra vitamin D khi

tm nng bui sng, dit vi khun (do c mt lng rt b tia cc tm), pht in, pht nhit, sy kh,

+ Hin nay ngi ta ang nghin cu thit b dn nh sng t nhin vo trong cc to nh nhm gim tin in cng nh c li cho sc kho.

3. Ngun sng nhn to v quang ph vch

Lng knh

nh sng mt tri

Tia sng n sc u ra lng knh

Ph nh sng

Hnh 1.1_ Th nghim quang ph lin tc

nm

Hnh 1.2_Th nghiph

m quang vch

n phng in trong cht kh

Lng knhKhe hp

Vt en

Hydro

Natri (Sodium)

Heli

Neon

Thu ngn


+ nh sng nhn to c quang ph t qung (quang ph vch). Hnh 1.2 l kt qu th nghim xc nh quang ph ca mt s ngun sng nhn to sau khi i qua lng knh:

+ Ni chung nh sng nhn to khng tt bng nh sng mt tri (xt di gc chiu sng). V mt tm - sinh l, tri qua hng triu nm tin ha, h thn kinh ca con ngi thch nghi hon ton vi nh sng ban ngy nn vi bt k ngun sng no khng phi l nh sng mt tri u khng tt i vi mt. c m ca con ngi lun lun hng n vic to ra cc ngun sng ging nh ban ngy, do nh gi cht lng ca cc ngun sng nhn to ngi ta thng ly nh sng ban ngy lm chun so snh.

nh sng n tuyp ta thng thy cng ch c mu xanh, tc l c quang ph vch mc d ban m ta cm thy n kh d chu. Vi s tin b ca k thut, hin nay ngi ta c th ch to cc ngun sng c kh nng pht ra cc bc x c quang ph lin tc gn vi nh sng trng nh n xenon, song gi thnh rt t nn ch yu dng cho cc loi xe hi t tin.

1.2. Mt s hin tng pht sng v phm vi ng dng trong chiu sng nhn to: 1. Hin tng pht sng do nung nng: Bt k vt th no c nhit > 00K u bc x nng lng di dng sng in t, khi

c nung nng n nhit khong 10000K s pht ra bc x nh sng (cng l loi sng in t). Nhit cng cao th cng nh sng tng ln v mu sc b ngoi cng tr nn sng hn. Cc loi n in chiu sng thng dng dng in t nng si t (dy tc) bng kim loi. Hin tng pht sng khi nung nng bng dng in c nh khoa hc Anh Humphrey DaVy pht hin nm 1802. Sau nh pht minh ngi M Edison mi ch to ra n si t u tin.

Hin tng pht x nh sng do nung nng c gii thch nh sau: Khi c in p t vo hai u dy tc, cc in t cc lp ngoi ca nguyn t c gii phng khi nguyn t v dch chuyn trong mng tinh th kim loi. Trong qu trnh di chuyn, in t lun lun c va chm vi cc nguyn t, do ng nng ca in t truyn mt phn cho nguyn t. Kt qu l cc nguyn t b kch thch v mt s in t lp trong nhy ra lp ngoi (nu lp cha y). in t ny c xu hng tr v v tr trng gn ht nhn hn (v tr n nh) v nu iu xy ra th in t s mt mt lng nng lng E (th nng) ng thi gii phng mt photon c bc sng = c.h/E (c th l nh sng nhn thy hoc khng nhn thy).

Nng lng bc x c th bao gm quang nng, nhit nng v bc x hng ngoi,... ng dng hin tng ny ch to cc loi n si t nh n si t chn khng

(trong dn dng 50W-75W), n si t halogen (cn gi l n halogen-Vonfram). 2. Hin tng pht sng do phng in: Hin tng ny do nh khoa hc Anh Edward Townsend pht hin u tin. Hin tng phng in trong cht kh l qu trnh din ra rt phc tp, ph thuc vo p

sut kh, cng sut ngun in v dng in trng. Tuy nhin c th m t tm tt thng qua th nghim sau y: cho ng phng in thy tinh cha hi kim loi hoc mt kh tr no p sut thp, bn trong c t 2 in cc v c ni vi ngun 1 chiu thng qua bin tr iu chnh c:

+ Khi in p tng ln th dng in tng theo (on AB). Nguyn nhn c dng in l




do cc ion t do tn ti trong cht kh. + n im B (im xy ra phng in) th dng in tng rt nhanh cn in p gim

xung n im M (im duy tr phng in). Nguyn nhn dng in tng l do hin tng ion ha cht kh lm cho s in t tng ln nhanh.

+ n im D (bng cch gim R) s xy ra hin tng phng in h quang. Nguyn nhn l do in cc b t nng qu mc lm pht x in t bng hiu ng nhit-ion.

Cn lu l nu p sut cao s xy ra hin tng phng in tia la ch khng phi phng in ta sng v p sut cao, hin tng phng in khng t duy tr c.

Khi ng dng hin tng ny vo n in chiu sng, ngi ta ch cho n lm vic trong khong B-D vi im lm vic M c xc lp nh in tr R gi l chn lu. in p ti im B c gi l in p phng in hay in p mi. Khi phng in, cc nguyn t kh b kch thch ln mc nng lng cao hn, sau tr v trng thi ban u th pht ra phton gy nn hin tng pht sng hng t cc m sang cc dng. nh sng pht ra thng n sc v mang mu c trng ca kh trong ng thy tinh. Ngoi nh sng nhn thy, ty vo cht kh m cn c cc tia hng ngoi hay t ngoi. Nu c pht tia t ngoi th ng phng in phi lm bng thy tinh c c tnh cn tia t ngoi (thy tinh natri cacbonat), trnh hy dit sinh vt sng, tia hng ngoi khng nguy him v n ch c tc dng nhit.

i vi ngun in xoay chiu hnh sin th chiu dng in duy tr trong ng thy tinh

lin tc thay i theo tn s ngun in. C dng in v in p trong ng phng in khng cn l hnh sin na nn n c xem l mt phn t phi tuyn. Mc d mt ngi khng cm nhn c nhng nh sng do n to ra l nh sng nhp nhy lin tc.

Hnh 1.4_ Phng in trong cht kh vi ngun in hnh sin

M

M

B

B

i

E

R u

Katot

m i

Anot

Hi kilo

300

200

100

u(V)

A

EB

CM

D

E

M

R=30k R=300

logi10-5 10-4 10-3 10-2 10-1 1

Hnh 1.3_ Th nghim phng in trong cht kh


Nng lng bc x gm quang nng, nhit nng, bc x hng ngoi, bc x t ngoi c t l thay i theo p sut v loi kh s dng.

ng dng hin tng ny ch to cc loi n hi phng in Natri p sut thp, Natri p sut cao, n halogen kim loi (hi thy ngn cao p),

3. Hin tng pht sng hunh quang Hin tng hunh quang c bit n vo gia th k 19 bi nh khoa hc ngi Anh

George G. Stoke. Khi cho nh sng t ngoi (khng nhn thy) chiu vo cht pht hunh quang th mt phn nng lng ca n bin i thnh nhit, phn cn li bin i thnh nh sng c bc sng di hn nm trong di quang ph nhn thy c. (inh lut Stoke)

Gii thch theo thuyt lng t nh trong hnh 1.5: mt photon bc x t ngoi (hnh bn tri) va chm vi mt electron ca mt nguyn t cht hunh quang, kch thch v a electron ny ln mc nng lng cao hn. Sau , electron ny ri xung mc nng lng thp hn v pht ra nh sng di dng mt photon (hnh bn phi) trong vng nh sng nhn thy c.

in t trng thi c bn

Photon pht x (nh sng nhn thy)

Mc nng lng thp

Mc nng lng cao

in t b kch thch

Hnh 1.5_ Gii thch hin tng pht sng hunh quang

Tia t ngoi

Ht nhn

ng dng hin tng ny ngi ta ch to ra n hunh quang gm bng thu tinh khng cho tia t ngoi xuyn qua, trong cha cht thu ngn p sut thp. Khi phng in, cc in t pht x t in cc kch thch nguyn t thu ngn v to ra tia t ngoi (bc sng 253,7nm), cc tia t ngoi p vo thnh ng (c qut bt hunh quang) lm n pht sng.

Nhn chung hiu sut pht sng ca n hunh quang kh cao. Cht hunh quang c rt nhiu loi nhng thng dng cht halophosphat canxi 3Ca(PO4)2.CaF2 qut vo bn trong thnh ng phng in mt lp mng.

Nng lng bc x t hin tng phng in ngoi tia t ngoi c th cn c tia hng ngoi, nhng theo nh lut Stokes ta khng th bin i tia hng ngoi v min nh sng nhn thy (bc sng ngn hn).

Cc loi n hunh quang hin nay gm T12-T10-T8-T5, compact, ngha ca cc k hiu ny c cp cc chng sau.

4. Hin tng pht sng ln quang



Ln quang l mt dng pht quang, trong cc phn t ca cht ln quang hp th nh sng, chuyn ha nng lng ca cc photon thnh nng lng ca cc electron sang trng thi lng t c mc nng lng cao nhng kh bn vng. Sau electron chm chp ri v trng thi lng t mc nng lng thp hn v gii phng mt phn nng lng tr li di dng cc photon.

Ln quang khc vi hunh quang ch vic electron tr v trng thi c km theo nh ra photon rt chm chp. Trong hunh quang, s ri v trng thi c ca electron gn nh tc thi khin photon c gii phng ngay. Do vy cc cht ln quang hot ng nh nhng b lu tr nh sng: thu nhn nh sng v chm chp nh ra nh sng sau .

S d c s tr v trng thi c chm chp ca cc electron l do mt trong s cc trng thi kch thch kh bn nn vic chuyn ha t trng thi ny v trng thi c bn b cm bi mt s quy tc lng t. Vic xy ra s tr v trng thi c bn ch c th c thc hin khi dao ng nhit y electron sang trng thi khng bn gn , t n ri v trng thi c bn. iu ny khin hin tng ln quang ph thuc vo nhit : nhit cng lnh th trng thi kch thch cng c bo tn lu hn.

a s cc cht ln quang c thi gian tn ti ca trng thi kch thch ch vo c miligiy, c mt s cht c th ln ti vi pht hoc thm ch vi gi. Trong thc t ta thy con om m pht sng c l nh cht ln quang.

Cht d quang l cht c cha cc nguyn t pht sng ln quang. Hin tng ln quang khng c ng dng trong k thut chiu sng v hiu qu thp v

trng thi pht sng khng bn. N ch dng trong ch to cc chi cho tr em, 5. Hin tng pht sng th cp: Ni cch khc y khng phi l ngun sng thc s nh cc hin tng nu trn.

Khi mt vt c chiu sng th bn thn n cng c th phn x mt phn nh sng gi l pht sng th cp. Ch c vt en tuyt i mi hp th ton b nh sng.

Da vo hin tng ny ta c th gii thch mu sc ca cc vt trong t nhin: S th hin mu ca vt l do nh sng phn x to thnh (v d vt mu phn x tia mu , cc mu khc th n hp th). Trc y c rt nhiu l thuyt mu sc khc nhau xut hin ch yu s dng trong ngnh dt nhum. Vi s ra i ca thuyt lng t, hin nay ngi ta xy dng hon chnh thuyt mu hin i da vo bn cht sng ht ca nh sng

Mt vt th bt k tip nhn nh sng chiu vo s xy ra cc hin tng : phn x, xuyn qua, hp th. Mi hin tng ny li c nhng tnh cht ring, v d phn x li c cc loi phn x u, phn x khuych tn,. Cc hin tng ny c nghin cu ch to cc b phn ca n (c bit l tm phn quang) nhm iu khin s phn b nh sng ca ngun sng hiu qu nht. Vn ny s xt trong cc phn sau.

1.3. Cc i lng c bn o nh sng 1. Gc khi (cn gi l gc c, gc nhn) - Khi nim: Xt mt ng cong kn bt k (L). T mt im O trong khng gian ta v cc ng

thng ti mi im trn ng cong (L) gi l cc ng sinh. Khi phn khng gian gii hn bi cc ng sinh ny c gi l gc khi nhn ng cong (L) t nh O.



o ca gc khi l din tch phn mt cu c bn knh r = 1, tm ti im O b ct bi gc khi trn.

=S

O r =1

(L)

Hnh 1.6_ nh ngha gc khi

- K hiu gc khi : (Ch ci Hy Lp, c l mega).

- n v : Sr (steradian) Steradian l gc khi m di gc ngi quan st

ng tm O ca mt qu cu R=1m th nhn thy din tch S=1m2 trn mt cu.

- ngha: Gc khi l gc trong khng gian, c trng cho gc nhn (tc l t mt im no nhn vt th di mt gc khi). Trong k thut chiu sng, gc khi biu th cho khng gian m ngun sng bc x nng lng ca n.

- V d tnh ton mt s gc khi: + Cho qu cu tm O bn knh R, mt hnh nn c

nh ti O ct mt cu vi mt din tch S th ln ca

gc khi l : 2RS= .

+ Cho 2 hnh cu bn knh R v kR ng tm O. Gi s mt gc khi chn hnh cu R vi din tch S1=2R2(1-cos) v hnh cu kR vi din tch S2= 2k2R2(1-cos). Khi gc khi l:

( ) ( )22222

21 )cos1(2)cos1(2

kRS

kRRk

RS ====

S = Din tch trn mt cu

R O

R

kR

S2=k2S

S1 O

Hnh 1.7a Hnh 1.7b

+ Cho mt cu tm O, bn knh R. Gc khi chn bi hnh nn nh ti O, gc nh 2,

din tch mt cu b chn l S. Ta c gc khi:

)cos1(2)cos(22 222 ==== RRRR

RRh

RS

Ta thy gc khi l i lng khng ph thuc bn knh R. Trng hp ti nh O nhn ton b mt cu (=1800) ta c gc khi ln nht = 4 (Sr) + Tnh gc khi chn din tch dS b tu t im O: khi ta coi dS l mt phng. Trn

dS ta ly im M l trng tm ca dS, sau v mt cu tm O bn knh R=OM th gc khi




nhn din tch dS t O l :

2

dS.cosd R

= Trong l gc hp bi vect php tuyn ca mt dS v OM, cn dS.cos l hnh

chiu ca dS ln phng OM. Do dS b tu nn dS.cos c xem l din tch m gc khi chn mt cu.

2. Thng lng nng lng ca bc x nh sng nhn thy Nng lng in cung cp cho ngun sng khng phi bin i hon ton thnh nh sng

m bin i thnh nhiu dng nng lng khc nhau nh ha nng, bc x nhit, bc x in t. Cc bc x nh sng ch l mt phn ca bc x in t do ngun pht ra. Di gc k thut chiu sng ta ch quan tm n nng lng bc x nh sng nhn thy m thi, do ngi ta a ra khi nim thng lng nng lng ca bc x nh sng nhn thy, l phn nng lng bc x thnh nh sng ca ngun sng trong mt giy theo mi hng c xc nh theo cc cng thc:

Ph nh sng lin tc : vi 380nm 1, 2 780nm 21

).(

dW

Ph nh sng ban ngy (loi ph lin tc): nm

nm

dW780

380

).(

Ph nh sng ri rc (quang ph vch): =

n

iiP

1)(

Trong : W() l phn b ph nng lng ca ngun sng (W/nm). P(i) l mc nng lng ca tia n sc th i pht ra t ngun sng (W). i l bc sng ca tia n sc th i tho mn 380nm i 780nm n v o ca thng lng l (W).

h a a

R

Hnh 1.7c

O

R

dS

M

n

d

Hnh 1.7d



3. Quang thng - Khi nim: Thng lng nng lng ca nh sng nhn thy l mt khi nim c ngha quan trng

v mt vt l. Tuy nhin trong k thut chiu sng th khi nim ny t c quan tm.

Tht vy, gi s c hai tia sng n sc mu (=700nm) v mu vng (=577nm) c cng mc nng lng tc ng n mt ngi th kt qu nhn c l mt ngi cm nhn tia mu tt hn mu vng. iu ny c th gii thch l do s khc x qua mt (vai tr l thu knh hi t) khc nhau: cc tia sng c b b lch nhiu v hi t trc vng mc, cc tia c ln th li hi t sau vng mc, ch c tia =555nm (vng) l hi t ngay trn vng mc. Trn c s ny ngi ta xy dng ng cong hiu qu nh sng V() ca mt ngi (hnh 1.8). ng cong 1 ng vi th gic ban ngy v ng cong 2 ng vi th gic ban m. Biu thc gn ng ca ng cong V() c cho trong ph lc cui sch, ng thi trong ph lc cng c bng gi tr ca hm V().

Nh vy r rng thng lng nng lng khng th dng trong k thut chiu sng phc v con ngi, do ngi ta phi a vo mt i lng mi trong ngoi W() cn phi k n ng cong V(), i lng ny gi l quang thng v c xc nh nh sau:

Ngun sng pht quang ph vch (n chiu sng): )(.)(.6831

i

n

ii VP

==

Ngun sng n sc : = 683.P().V() vi =const Ngun sng c quang ph lin tc = 2

1

).().(683

dVW

nh sng ban ngy 780

380

683 ( ). ( ).nm

nm

W V d = Trong cc cng thc trn :

n l tng s tia sng n sc do ngun pht ra P(i) l mc nng lng ca tia n sc th i (W). W() l phn b ph nng lng ca cc tia sng lin tc (W/nm) i l bc sng ca tia n sc th i (nm). 683 lm/W l hng s vt l xut pht t nh ngha n v cng sng (Cadela),

biu th s chuyn i n v nng lng sang n v cm nhn th gic. Gi tr 683 c a vo to ra gi tr tng ng vi nh ngha c ca cadela.

1 v 2 l gii hn bc sng (cn di v trn) ca quang ph lin tc. - ngha: V bn cht, quang thng cng chnh l nng lng nhng y n v tnh

khng phi bng Ot m bng Lumen. y l i lng rt quan trng dng cho tnh ton chiu sng, th hin phn nng lng m ngun sng bc x thnh nh sng ra ton b khng gian xung quanh. thy r s khc nhau gia Ot v Lumen ta c s so snh sau:

1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0

400 450 500 550 600 650 700 nm

Hnh 1.8

12


Gi s c mt ngun sng cng sut 1W bin i ton b cng sut ny thnh nh sng nhn thy. Nu nh sng n pht ra l mt tia n sc =555nm (mu vng) s cho quang thng 683 lm nhng nu nh sng pht ra l quang ph lin tc vi nng lng phn b u th quang thng khong 179 lm (xem ph lc 1).

- K hiu: (k hiu ch ci Hy Lp, c l phi) - n v: Lm (Lumen). Lumen l quang thng do ngun sng pht ra trong mt gc khi

bng 1 Sr. - V d gi tr quang thng mt s ngun sng thng dng: + Xt mt ngun sng im c cng sng I khng i theo mi phng th quang

thng l : IId

44

0

== + Thit b dng o quang thng gi l Lumen k. + Quang thng do mt tri gi xung tri t l 145.1017lm. 4. Quang hiu - nh ngha: Quang hiu l t s gia quang thng do ngun sng pht ra v cng sut

in m ngun sng tiu th. - ngha: Trong k thut chiu sng ngi ta khng dng khi nim hiu sut theo ngha

thng thng (tnh theo t l %) m s dng khi nim quang hiu. Quang hiu th hin y kh nng bin i nng lng m ngun sng tiu th thnh quang nng.

Mt s ti liu gi khi nim ny l hiu sut ca ngun sng. Tuy nhin, nu ta s dng khi nim hiu sut th s lin tng n t l % (gi tr 1) gia cc i lng cng n v o. Tri ngc hon ton vi quan nim v hiu sut, quang hiu li c gi tr ln hn 1 rt nhiu v l t s ca 2 n v o khc nhau (lm/W) do vic dng khi nim hiu sut l khng hp l.

- K hiu: (Ch ci Hy Lp, c l ta) - n v: lm/W (lumen/Ot) - V d: Quang hiu mt s ngun sng thng dng (theo ti liu Schrder nm 2006)

Ngun sng Cng sut (W) Quang thng (Lm) Quang hiu (Lm/W)

Bng n dy tc 100 1500 15

Bng hunh quang 36 2600 80

Bng compact 20 1200 60

Bng cao p thy ngn 250 13000 52

Bng cao p MetalHalide 250 20000 80

Bng cao p Sodium 250 27000 108

5. Cng sng - Khi nim: + Xt trng hp mt ngun sng im t ti O v ta quan st theo phng Ox. Gi d



l quang thng pht ra trong gc khi d ln cn phng Ox. Cng sng ca ngun theo

phng Ox c nh ngha l : =

ddI

+ Cng sng I ca ngun ph thuc vo phng quan st. Trong trng hp c bit, nu I khng thay i theo phng (ngun ng hng), ta c quang thng pht ra trong ton khng gian l:

4 I = . O

d I d x

- ngha : Cng sng l i lng quang hc c bn, cc i lng quang hc khc u l i lng dn sut xc nh qua cng sng.

Hnh 1.9

- K hiu : I (Vit tt ca ting Anh l Intensity : cng ) - n v : + Cd (cadela). Cadela c ngha l ngn nn, y l mt trong 7 n v o lng c bn

(m, kg, s, A, K, mol, cd) + nh ngha Cd (t thng 10-1979): Cadenla l cng sng theo mt phng cho

ca ngun pht bc x n sc c tn s 540.1012Hz (=555mm) v cng nng lng theo phng ny l 1/683 W/Sr

- V d : + n si t 40W/220V c I= 35 Cd (theo mi hng) + Ngn nn c I=0,8 Cd (theo mi hng). + Theo nh ngha vi ngun sng n sc =555nm th 1W=683lm. Nu ngun sng

n sc c 555nm th 1W=683.V(). V d : ngun sng n sc c =650nm th 1W=683.0,2=136,6 lm.

6. ri - Khi nim: Gi thit mt S c ri sng bi mt ngun sng. ri ti mt im no

trn mt S l t sdSdE = , trong d l quang thng ton phn do ngun gi n din

tch vi phn dS ln cn im cho. Nu mt S c chiu sng u vi tng quang thng gi n S l th ri ti mi

im trn mt S l ES=

- K hiu : E

n

O

dS M

d

I

dScos

Hnh 1.11 Hnh 1.10_nh ngha ri

dS

d

S

- n v: Lux hay Lx (c l luych) Lux l n v o chiu sng ca mt b mt. chiu sng duy tr trung bnh l cc

mc lux trung bnh o c ti cc im khc nhau ca mt khu vc xc nh. Mt lux bng




mt lumen trn mi mt vung. - ngha: Th hin lng quang thng chiu n 1 n v din tch ca mt b mt c

chiu sng, ni cch khc n chnh l mt phn b quang thng trn b mt chiu sng. - nh lut t l nghch bnh phng : Xt mt ngun sng im O, bc x ti mt nguyn t hnh trn dS c tm M cch O mt

khong r. Cng sng ca ngun theo phng OM l I (hnh 1.11). Do dS kh nh nn

xem l mt phng, do ta gi l php tuyn ca dS v l gc gia ( , OM). Ta c cng thc ri:

n

n

===dSr

dSIdSdI

dSdE

.cos...

2

Cng thc ny cho thy ri trn b mt no ph thuc vo khong cch r v

nghing ca mt so vi phng quan st v n c s dng ch yu trong cc tnh ton chiu sng. y chnh l cng thc ca nh lut t l nghch bnh phng.

- Mt s gi tr ri thng gp: * Tra nng khng my 100.000 lux * m trng trn khng my 0,25 lux * Ban m vi h thng chiu sng cng cng 10-30 lux * Nh bnh thng ban m: 159-300lux * Phng lm vic: 400-600lux.

7. sng (cn gi l trng): - Khi nim: Cho mt mt pht sng S c kch thc gii hn (c th l b mt ca ngun sng hoc b mt vt phn x nh sng,). sng ti mt im no

trn mt S l t s dRdS= , trong d l quang thng

do phn t dS (ln cn im cho) pht ra theo mi hng. Mt pht sng u l mt c trng nh nhau mi im ca mt - c im v ngha: + trng c trng cho s pht sng theo mi phng ca vt pht sng (bao gm

ngun sng v nh sng phn x ca vt c chiu sng). + Xt v cng thc tnh v th nguyn th trng ging ri nhng ri xt b

mt vt c chiu sng bi ngun sng khc cn trng xt b mt ca vt m bn thn n pht sng. n v ca ri l Lux cng khc n v trng l Lm/m2.

+ Ngun sng y cn hiu theo ngha rng hn l "mt pht sng" bao gm ngun pht ra nh sng v ngun nh sng phn x ca vt c chiu sng.

+ ri E trn b mt c chiu sng khng ph thuc vo h s phn x b mt nhng trng ca b mt c chiu sng th ph thuc vo h s phn x b mt.

- K hiu: R - n v: Lm/m2 l trng ca mt ngun sng hnh cu c din tch mt ngoi 1m2 pht

ra quang thng 1 Lumen phn b u theo mi phng.

cos.2rIE =

Hnh 1.12_nh ngha sng

dS

d

S


8. chi

dScos

M

O

dI

n

dS

- Khi nim: + Hai bng n si t hnh trn cng sut 40W

th c cng quang thng. Mt bng thy tinh trong, mt bng thy tinh m th bng thy tinh trong s gy chi mt hn. iu ny c gii thch l: vi bng thu tinh m, tia sng bc x t ngun khi p vo b mt thu tinh m (v bng n), n b tn x theo nhiu hng v cng sng theo mt hng nht nh gim i so vi cng ca tia ti do t chi hn chi ph thuc vo cng sng.

Mt khc vi n pha xe my nu nhn trc din ta thy chi mt nhng nu nhn nghing mt gc no th s bt chi mt hn chi ph thuc vo phng quan st, c c trng bng din tch biu kin ca mt pht sng theo phng quan st. Hnh 1.13_nh ngha chi

T nhng nhn xt trn ta thy cn thit phi a ra khi nim chi ph thuc vo cng sng ca ngun v din tch biu kin ca mt pht sng.

+ Mt ngi t ti im O quan st b mt pht sng dS theo phng OM. B mt dS nghing mt gc so vi phng OM. Gi dI l cng sng pht ra bi dS theo phng OM th ta c nh ngha chi l cos.dS

dIL = . - ngha: + Th hin mt phn b cng sng pht ra t mt n v din tch ca b mt

theo mt hng xc nh n mt ngi quan st. + chi ph thuc vo tnh cht phn quang ca b mt v hng quan st (khng ph

thuc vo khong cch t mt n im quan st). + Nhn chung mi vt th c chiu sng t nhiu u phn x nh sng (ng vai tr

nh ngun sng th cp) nn cng c th gy ra chi mt ngi. V d ban m nh sng ht ln t mt ng nha c chiu sng cng c th lm chi mt ngi li xe.

+ chi ng vai tr rt quan trng khi thit k chiu sng, l c s khi nim v tri gic v tin nghi nhn.

+ chi trung bnh ca mt ng l tiu chun u tin nh gi cht lng ca chiu sng ng ph.

- K hiu: L - n v: Cd/m2. 1 Cd/m2 l chi ca mt mt phng pht sng u c din tch 1 m2

v c cng sng 1 Cd theo phng vung gc vi ngun . - V d v chi mt s b mt:

+ B mt n hunh quang: 5.000-15.000cd/m2 + B mt ng nha chiu sng vi ri 30lux c chi khong 2cd/m2

+ Mt tri mi mc : khong 5.106 Cd/m2 + Mt tri gia tra : khong 1,5 2.109 Cd/m2

9. Nhit mu: Nhit mu ca mt ngun sng c th hin theo thang Kelvin (K) l biu hin mu

sc ca nh sng do n pht ra. Tng tng mt thanh st khi ngui c mu en, khi nung




u n khi n rc ln nh sng da cam, tip tc nung n s c mu vng, v tip tc nung cho n khi n tr nn nng trng. Ti bt k thi im no trong qu trnh nung, chng ta c th o c nhit ca thanh thp theo Kelvin (0C + 273) v gn gi tr vi mu c to ra.

i vi n si t, nhit mu chnh l nhit bn thn n. i vi n hunh

quang, n phng in (ni chung l cc loi n khng dng si t) th nhit mu ch l tng trng bng cch so snh vi nhit tng ng ca vt en tuyt i b nung nng.

Khi ni n nhit mu ca n l ngi ta c ngay cm gic l ngun sng m, trung tnh hay l mt. Ni chung, nhit cng thp th ngun cng m, v ngc li. d hnh dung iu ny ta xt mt s gi tr nhit mu sau y:

25000K - 30000K Lc mt tri ln, n si t 45000K - 50000K nh sng ban ngy quang my 60000K - 10.0000K nh sng khi tri nhiu my (nh sng lnh) Khi thit k chiu sng cn phi chn nhit mu ca ngun sng ph hp vi c im

tm-sinh l ngi, l vi ri thp th chn ngun sng c nhit mu thp v ngc li vi yu cu ri cao th chn cc ngun sng "lnh" c nhit mu cao. c im sinh l ny c Kruithof chng minh. Qua cc cng trnh nghin cu ca mnh, ng xy dng c biu Kruithof lm tiu chun u tin la chn ngun sng ca bt k n thit k chiu sng no (tt nhin sau cn c cc tiu chun khc).

Trong biu Kruithof, vng gch cho gi l vng mi trng nh sng tin nghi. Vi mt ri E (lux) cho trc, ngi thit k chiu sng phi chn ngun sng c nhit mu nm trong min gch cho m bo khng nh hng n tm-sinh l ca con ngi, nu khng m bo iu kin ny s gy ra hin tng " nhim nh sng", c th gy tn hi n sc khe.

10. hon mu (cn gi l ch s th hin mu): Cng mt vt nhng nu c chiu sng bng cc ngun sng n sc khc nhau th mt

s cm nhn mu ca vt khc nhau, tuy nhin bn cht mu sc ca vt th khng h thay i. V d mt t giy bnh thng mu , nu t trong bng ti n c th c mu xm, tuy nhin ta vn ni l t giy mu .

Nh vy cht lng nh sng pht ra ca ngun sng cn phi c nh gi qua cht lng nhn mu, tc l kh nng phn bit mu sc ca vt t trong nh sng . nh gi

Hnh 1.14_ Biu Kruithof 50 100 200 300 400 500 1000 1500 2000

ri (lux)

Nhit mu (0K)

7000

6000

5000

4000

3000

2000

Mi trng

tin nghi


s nh hng nh sng (do ngun pht ra) n mu sc ca vt, ngi ta dng ch s hon mu hay cn gi l ch s th hin mu ca ngun sng, k hiu CRI (Color Rendering Index). Nguyn nhn s th hin mu ca vt b bin i l do s pht x ph nh sng khc nhau gia ngun sng v vt c chiu sng.

Ch s CRI ca ngun sng thay i theo thang chia t 0 n 100. Gi tr CRI=0 ng vi ngun nh sng n sc khi lm bin i mu ca vt mnh nht, CRI=100 ng vi nh sng mt tri khi mu ca vt c th hin thc cht nht. Ni chung ch s CRI cng cao th cht lng ngun sng c chn cng tt. d p dng trong k thut chiu sng, ngi ta chia CRI thnh 4 thang cp sau:

Bng phm vi ng dng ca cc nhm hon mu

Nhm

hon mu Ch s hon

mu CRI Cht lng nhn mu Cht lng nhn mu v phm vi ng dng

1A CRI > 90 Cao Cng vic cn s hon mu chnh xc, v d vic kim tra in mu, nhum mu, xng v

1B 80 < CRI < 90 Cao Cng vic cn nh gi mu chnh xc hoc cn c s hon mu tt v l do th hin, v d chiu sng trng by

2 60 < CRI < 80 Trung bnh Cng vic cn s phn bit mu tng i

3 40 < CRI < 60 Thp Cng vic cn phn bit mu sc nhng ch chp nhn biu hin s sai lch mu sc t

4 20 < CRI < 40 Thp Cng vic khng cn phn bit mu sc

i vi chiu sng nh dn thng t quan tm n CRI, nhng gia nh c mc sng cao

mi ch n tiu chun ny v tt nhin khi mi trng sng s tin nghi hn km theo chi ph u t tng ln.

i vi chiu sng ng ph ch c mc ch m bo an ton giao thng l chnh hn na chi ph u t ban u kh ln nn gn nh khng quan tm n ch s CRI.

Cui cng cn lu : chng ta rt d b nhm ln gia nhit mu v hon mu, do y cn nhc li: nhit mu biu th mu sc ca ngun sng - l ni nh sng pht ra, cn hon mu biu th chnh xc mu ca ngun khi chiu ln vt th.

1.4. Cc nh lut quang hc v ng dng trong k thut chiu sng : 1. S phn x: a) S phn x u: - Hin tng ny tun theo nh lut quang hnh nghin cu trong gio trnh Vt l i

cng: Gc ti ca tia sng chiu ln b mt phn x bng gc phn x. S phn x u c

c trng bng h s phn x u px = pxdi

< 1, trong px, i ln lt l quang thng

phn x u v quang thng ri ti din tch b mt ang xt.



- ng dng : S phn x u l trng hp phn x l tng, xy ra trn cc vt liu rt mn, nhn

tuyt i. Hin tng ny c dng trong nghin cu ch to tm phn quang ( iu khin phn b nh sng theo mun) hoc tnh ton chi b mt cc vt liu mn, phng c phn x u.

Phn tn

nIn

Khuych tn u I = In.cos

I

n

Khuych tn hn hp

I

Ir

r

n In

i

I = In.cos v i = r

n

r i

u i = r

Hnh 1.15_ Cc hin tng phn x

b) S phn x khuych tn - Hin tng ny khng tun theo nh lut quang hnh. c im l khi c tia sng chiu

n b mt phn x khuych tn, cc tia sng phn b phn x i theo nhiu hng khc nhau. u mt cc vect cng sng phn x nm trn mt mt cong no . S phn x

khuych tn c c trng bng h s phn x khuych tn pxkt= pxkti

< 1, trong pxkt, i

ln lt l quang thng khuych tn v quang thng ri ti din tch b mt ang xt. Trong thc t, trn b mt cc vt liu lun xy ra ng thi hai hin tng phn x u v phn x khuych tn do ngi ta nh ngha h s phn x hn hp px = px + pxkt =

pxd pxkt

i

+


truyn x u c c trng bng h s truyn x u tx = txdi

< 1, trong tx, i ln

lt l quang thng truyn x u v quang thng ri ti din tch b mt ang xt. - ng dng : Nghin cu ch to knh bo v phng cho b n, ch to bng n bng

thu tinh trong sut (bng n si t, ng phng in,). b) S truyn x khuych tn: - Hin tng ny khng tun theo nh lut quang hnh. c im l khi c tia sng chiu

n b mt truyn x khuych tn, cc tia sng phn b truyn i theo nhiu hng khc nhau. u mt cc vect cng sng truyn x nm trn mt mt cong no . S truyn

x khuych tn c c trng bng h s truyn x khuych tn txkt = txkti

< 1, trong

txkt, i ln lt l quang thng truyn x khuych tn v quang thng ri ti din tch b mt ang xt. Trong thc t, trn b mt cc vt liu lun xy ra ng thi hai hin tng truyn x u v truyn x khuych tn do ngi ta nh ngha h s truyn x hn hp tx = tx + txkt



Khc x l hin tng thay i hng ca cc tia sng lin tip qua cc tit din lng knh. Trong k thut chiu sng, a s knh bo v cc b n c dng phng, tuy nhin knh bo v ca mt s b n li c ch to dng rng ca ( mt trong) nhm mc ch phn tn nh sng gim chi. Thng thng gc nh ca rng ca c nghin cu rt k khc x nh sng theo mc ch cho trc. Nu gc nh bng 900 th ta gi l b n hnh t ong.

Gi i1 l gc gia php tuyn mt trong v tia ti (gi s tia ti vung gc vi mt ngoi) i4 l gc gia php tuyn mt ngoi vi tia ra khi knh n. n l chit sut vt liu lm knh. l gc nh.

Ta c quan h gia gc ti v gc ca tia ra l 4cos

2sin . os arcsin2

i n cn

= +

vi n=1,6 (thu tinh), khi : =300 th i4=800 =900 th i4=300 =1500 th i4=090

Nh vy gc nh s cho php iu chnh hng ca tia sng 4. S che chn: B phn che chp ca mt b n chiu sng thng ch to bng cc vt liu mu en

hoc vt liu m nhm ngn cn mt ngi nhn trc tip gy ra la mt, n cn c tc dng chng hi m v cc vt l bn ngoi xm nhp vo bn trong n. Phm vi che chn c c trng bng gc gia ng thng ng i qua tm ngun sng v phng m mt ngi bt u nhn khng b la mt (hoc khng nhn thy ngun sng).

5. S hp th: Khi nh sng chiu vo bt k vt liu no cng b hp th mt phn nng lng. Mc

hp th t hay nhiu ph thuc vo mt s yu t nh: loi vt liu, bc sng ca tia sng (mu) v gc chiu ca tia sng vo vt liu.

c trng cho s hp th nh sng ca vt liu ngi ta a ra khi nim h s hp th

i1 Mt trong

i4

Knh n

Tia ti

Mt ngoi Tia l

Hnh 1.17_ Hin tng khc x


, l t s gia quang thng m vt th hp th h v quang thng ri ti vt liu s. h

s

= i vi mt loi vt liu c th th h s hp th cng khng phi l hng s m cn ph

thuc vo bc sng chiu vo vt liu. H s hp th ca mt s vt liu khi tia ti l nh sng trng c cho trong bng sau:

Vt liu H s hp th (%)

Bng pha l trong 5-12 Bng thu tinh sng 10-20 Bng thu tinh vng nht 15-20 Bng ht mn xanh nht 15-25 Bng thu tinh nhm 15-30 Bng nha sng 20-40 Bng thu tinh mu sa 15-40 Bng thu tinh m 20-30 Bng thu tinh vng 40-60 Bng thu tinh vng m 30-60

- ng dng: hin tng hp th c nghin cu ch to cc loi vt liu c h s hp

th t nht trong n chiu sng, c bit l cc vt liu che chn (v n), vt liu truyn x (knh bo v n),

6. nh lut Lambert v s khuych tn u :

Cng phn x

Tia ti

S: Mt phn x Cng truyn x

Tia ti

S: Mt truyn x

Hnh 1.18_ Hin tng phn x v truyn x khuych tn u

nh lut Lambert l nh lut v s phn x khuych tn u v s truyn khuych tn

u. y l trng hp c bit ca hin tng khuych tn nhng li thng gp trong k thut chiu sng (v d b mt cc bng n sn m, b mt n tuyp, mt nn bng gch men,).

Gi thit nh sng tia ti p vo b mt S c xy ra ng thi hin tng phn x khuych tn u v s truyn khuych tn u (gi s b qua hin tng hp th, phn x u, s truyn u d chng lun lun tn ti). Hai hin tng ny u tun theo nh lut Lambert.



a) Trng hp phn x khuych tn u : Xy ra khi mt S lm t vt liu mn nh t giy, sn m, vt liu xy dng dng bt, Gi thit mt S c h s phn x


CHNG 2 MT NGI V S CM TH NH SNG

2.1 Cu to mt ngi Mt ngi l mt i tng c bit trn c th ngi. Di gc nhn ca th ca th n l

"ca s tm hn", di gc ca sinh hc th n l mt b phn ca c th c cu trc phc tp, di gc vt l n l mt thu knh hi t,.... Ni chung, ty vo mc ch nghin cu m mt c mt vai tr ring.

Trong bi ging ny mt ngi c nghin cu di gc ca ca k thut chiu sng, tc l xt n s cm th nh sng v thu nhn hnh nh vi vai tr nh mt thu knh hi t.

Hnh 2.1_ Cu to mt ngi

1. Hin tng th gic: Mt ngi thc ra khng nhn. Mt ngi ng vi tr l cng c thu cc n tng quang

hc thnh cc tn hiu c ngun gc in cho php b no ti to li hnh nh v gi l hin tng th gic. C hai loi hin tng th gic l th gic ban ngy v th gic hong hn. Th gic ban ngy lin quan n s kch thch cc t bo hu sc (t bo hnh nn) cn th gic hong hn lin quan n s kch thch cc t bo v sc (t bo hnh que).

2. Hin tng iu tit ca mt: Gic mc v nht l thy tinh th c th iu tit tp trung hnh nh ln vng mc cho

d vt c quan st xa hay gn. 3. Vng mc: L ni tp trung hng triu t bo hnh que v hnh nn rt nhy vi nh sng. Khi b nh

sng kch thch n gi nhng xung in theo t bo thn kinh th gic ln no gii m hnh nh, gip chung ta nhn thy vt.

4. Khi nim con mt quc t:



Vic thu cc n tng th gic ca con mt lun bin i theo quy lut khng tuyn tnh

v bin thin theo thi gian. iu ny lin quan n tui tc, sc khe ca mi ngi v khuyt tt ca mt. Do CIE nh ngha con mt quc t l con mt i vi ngi quan st quy chiu trung bnh di 30 tui.

2.2 S gii m hnh nh: - Khi nim: t tiu nh sng i t vt mun nhn, mt s co hoc gin c mt thay

i tiu c v hnh dng ca h thu knh : thu tinh th + gic mc. Hnh nh qua thu knh hai mt li s b o chiu v tp trung trn vng mc. Thng qua t bo thn kinh th gic, nh sng kch thch trn vng mc c truyn ln no (trung khu thn kinh th gic nm sau gy) v ti y hnh nh c chuyn i v o chiu tr li ghi nhn hnh nh tht ca vt mun nhn. Hin tng ny gi l s gii m hnh nh. S gii m hnh nh thc hin c l nh vng mc c cc t bo thn kinh th gic rt nhy vi nh sng l t bo hnh nn v t bo hnh que.

- T bo hnh nn: C khong 7 triu t bo, chim vng gia vng mc (vng h) v c kch thch bng cc mc chiu sng cao (cn gi l th gic ban ngy). Chng gip no phn bit v lm ni ln cc chi tit tinh t trong hnh nh, ngoi ra chng con truyn cc tri gic mu. T bo hnh nn gm ba loi t bo cm nhn khc nhau v mu sc gi l ba sc t quang hnh nn. Ba loi t bo ny nhy cm cc i vi cc bc sng (R), xanh lc (G), xanh lam (B). Khi mt mu bt k no truyn n vng mc s kch thch 3 loi t bo ny vi mc khc nhau, sau truyn thng tin v no ti to mu sc ca vt.

- T bo hnh que: C khong 120 triu t bo, bao ph phn cn li ca vng mc, c ln ln mt t t bo hnh nn v c kch thch bng mc chiu sng thp (gi l th gic ban m). Chng chu trch nhim v mt hnh nh tng th trn din rng nhng khng i vo chi tit, ngoi ra chng cn truyn cc tri gic en trng nn hu ch cho vic nhn vo ban m.

T bo hnh que

T bo hnh nn

Nhn t bo

Hnh 2.2

S vn ng ca hai loi t bo ny khng c ranh gii r rt, chng lm vic nhiu hay t ty vo mc chiu sng, nht l trong min trung gian gia th gic ban ngy v th gic ban m.

2.3 Qu trnh thch nghi : L qu trnh th gic ban m hot ng. Vo ban m, khi ang trong phng c nh

sng bc ra ngoi tri ti, t bo hnh que (th gic ban m) khng th t ngay mc hot ng ti a ca n m cn c thi gian quen dn gi l qu trnh thch nghi. Ngc li nu ta chuyn t ni ti sang ni sng th t bo hnh nn (th gic ngy) cng cn c thi gian thch nghi nhng thi gian ny nhanh hn nhiu so vi qu trnh thch nghi ca th gic ban m. Nu mc chuyn th gic qu t ngt cng c th lm tn hi n vng mc.

2.4 Cm gic chiu su ca vt cn nhn:



Con ngi c hai mt khc nhau nn no thu c hai hnh nh hi khc nhau v tin hnh gii m khin cho ta cm nhn c chiu su ca vt cn nhn. Nu ta nhn bng mt mt th cm gic chiu su vn cn nhng gim hn. Trung bnh hai con mt cch nhau 6 cm nn vi khong cch nhn > 450 m th nh hin trn vng mc ca hai mt trng nhau nn ta khng cm nhn c chiu su vt cn nhn.

2.5 Cc cn v cc vin ca mt : Khi quan st vt th thu tinh th t ng iu chnh cong ca n, ging nh thay i

tiu c thu knh hi t, do nh thu c ri ngay trn vng mc gip mt nhn r vt cho d n xa hay gn. Cng nhn xa thu tinh th cng dt v tri li, cng nhn gn th thu tinh th cng trn.

Tuy nhin cng cn nhn thy kh nng iu chnh ca mt c gii hn. Cc cn l khong cch nh nht m nh ca vt cn nhn nm ngay trn vng mc. Nu nhn gn hn im cc cn th nh khng r, mt phi iu tit nn gy mi mt v lu ngy c th gy ra tt khc x. Cc cn ca mt chun c khong 20-25cm do khi c sch nn xa hn im cc cn trnh mi mt.

Cc vin ca mt ngi bng v cng.

Hnh 2.3_ Trng nhn

Trng nhn ng Trng nhn ngang

550-600

700-750620

940

2.6. Trng nhn ca mt : Trng nhn ca mt ngi

bnh thng c CIE tha nhn nh sau : khi nhn thng th phm vi nhn c gii hn bi:

- Nhn ngang : 1800 - Nhn ng: 1300 - Nhn trung tm: 20 Khi thit k chiu sng nn ly

trng nhn bng 1/2 gi tr nu trn m bo nhn r

2.7 tng phn : - Mt t giy trng t trn mt mt bn mu trng th rt kh nhn din t giy. Tri li

nu t t giy ny trn mt bn mu en th nhn din c mt cch r rng. y cng mt t giy mu trng nn cng chi nhng c nhn din mt cch khc nhau l do nhy ca mt vi s tng phn khc nhau, do ngi ta a ra nh ngha tng phn C nh sau:

b

b

LLL

C= 0

Trong : L0 l chi ca vt cn nhn Lb l chi ca nn t vt cn nhn (ch b vit tt ca background : mt nn). C trong Ting Anh l Constrast (ngha l tng phn). Gi tr C ngoi ph thuc



chi ca nn cn ph thuc vo kch thc ca vt: vt cng ln th tng phn cng cao. Theo thng k vi a s mi ngi th mt ch c th phn bit c vt c chi L0 t trn nn c chi Lb khi C 0,1. Tuy nhin thc t th mu sc v kch thc vt cng nh hng n kh nng phn bit ca mt nn khi thit k chiu sng phi cn c vo iu kin mi trng tnh ton mc chiu sng va .

- Ngng tng phn Cth : L gi tr sao cho khi CCth th vt c nhn thy cn C



0 02

( ) ( )v b v bb v b v b

0 bL L L L L L L LCL L L L L

+ + = =+ + 5m v s n ln nn trong tiu chun cng quy nh ch xt n h s chi la khi 5m


CHNG 3 CC LOI NGUN SNG NHN TO THNG DNG

Trong phn ny ta ln lt nghin cu cu to ca cc loi ngun sng nhn to thng

dng - tri tim ca b n chiu sng. y ta ch nu s b cu to, nguyn l hot ng, cc c im chnh di gc ng dng m khng i su gii thch phn tch cc hin tng quang hc nh: phn tch qu trnh gi ha, s bin i quang thng theo in p, hin tng m, hin tng en 2 u ng phng in, Cc vn ny cn phi tm c cc ti liu chuyn su hoc tham kho ti liu ca cc nh ch to.

3.1 Bng n nung sng:

nh sng (10%)

Tht thot nhit v i lu (20%)

Gin nng lng

Dy tc

u dy in

ng x ui n

Gi

V bng n Kh tr

Mc nng lng

Bc x hng ngoi (70%)

400 500 600 700 760

Hnh 3.1_Cu to, gin nng lng v ph mu ca bng n si t 1. Cu to ca bng n nung sng (hnh 3.1): a) Dy tc (si t):

Hnh 3.2_Cc loi dy tc

+ Ch to t vt liu chu nhit (thng l vonfram, tungsten, chu c nhit rt

cao, c khi n 36500K). + Khi b nung nng, si t ch yu pht x cc tia trong vng hng ngoi (1000 m n

0,78 m ) khng nhn thy c. Dng in chy qua dy tc lm nng n, qu trnh ny lm



cho in tr dy tc tng ln v n li cng b t nng cho n khi nhit to ra cn bng vi nhit tn ra khng kh.

+ Nhit cng cao th ph nh sng cng chuyn v vng nhn thy v mu sc nh sng cng trng hn. Tuy nhin nhit cao s lm bay hi kim loi lm dy tc nn ngi ta thng bm kh tr (Nit, Argon, Kripton) vo bng n lm chm qu trnh bay hi nhng ng thi cng lm tng tn tht do cc cht kh ny dn nhit.

+ Khi kim loi bay hi s ngng ng trn b mt bng lm n b m i. + V cu to, dy tc c rt nhiu loi nh hnh 3.2. b) V bng n: + Ch to bng thy tinh c pha ch. + p sut kh tr bm vo bng rt thp trnh tn nhit ra ngoi mi trng. + gim chi, mt trong bng n c ph lp bt m. c) ui n: Nhim v ui n l ni tip xc ngun in cung cp cho si t. + ui gi B15 hoc B22 + ui xoy E14, E27, E40 d) c im: - u im: + Ni trc tip vo li in m khng cn thit b ph no. + Kch thc nh + S dng n gin, bt sng ngay + Ch s hon mu tt, xp x bng 100 + Gi thnh r + To mu sc m p, khng nhp nhy. - Nhc im: + Hiu qu pht sng rt thp do nng lng nhit tn ra mi trng ln. + Quang thng, tui th ca n ph thuc mnh vo in p ngun. + Hin nay khng khuyn khch s dng trong dn dng v cng nghip nhng vn dng

trong chiu sng s c, chiu sn an ton v n lm vic c vi in p thp. 2. Mt s loi bng n nung sng thng dng: a) Bng n nung sng kiu chn khng hoc p sut kh tr: Bng n nung sng hot ng nh mt vt en, pht ra cc bc x c la chn vng

nh sng nhn thy. Bng n c th l chn khng hoc np kh tr. Sau mt thi gian s dng, bng n thng b ti i l do dy tc kim loi (vonfam) b bay hi ngng li trn b



mt bng. Nu bng ht chn khng th nhit ta ra khng kh gim xung, do hiu sut ngun

sng cao hn. Tuy nhin ch chn khng, khi b nung nng ln nhit rt cao kim loi lm dy tc s b bay hi nhanh, do loi bng ny ch ch to cng sut 75W.

lm chm qu trnh bay hi kim loi ngi ta thng cho thm kh tr (nit, argon, kripton) vo trong bng nn cng sut c th tng trn 75W nhng i li nhit ta ra mi trng s ln hn. i vi nhng loi n thng dng, hn hp kh Agon-Nit vi t l 9/1 c s dng nhiu do gi thnh thp. Kripton hoc Xenon kh t (do cng ngh tinh ch chng rt phc tp) nn ch c s dng trong nhng ng dng c bit nh n chu k hoc khi c yu cu hiu sut rt cao.

b) Bng n nung sng dng kh halogen: n nung sng dng kh halogen l mt loi n nung sng c dy tc bng vonfam

ging nh n si t bnh thng, tuy nhin bng n c bm y bng kh halogen (Iod hoc Brom). Nguyn t vonfam bay hi t dy tc nng v di chuyn v pha thnh ca bng n. Cc nguyn t vonfam, oxy v halogen kt hp vi nhau ti thnh bng to nn phn t vonfam oxyhalogen. Nhit thnh bng gi cho cc phn t vonfam oxyhalogen dng hi. Cc phn t ny di chuyn v pha dy tc nng ni nhit cao hn tch chng ra khi nhau. Nguyn t vonfam li ng li trn vng mt hn ca dy tc nn bng n khng b m.

Nh c hi halogen nn nhit t nng n cho php cao hn, do nh sng pht ra trng hn (nhit mu c th t 29000K), hiu sut ca n cng cao hn so vi n bm kh tr hoc chn khng.

Hnh 3.3_ Bng n si t dng kh halogen

c im: Gn hn, tui th di hn, sng trng hn, gi cao hn, nhiu tia hng ngoi

hn, nhiu tia cc tm hn. 3.2 Bng n hunh quang

1. c im cu to: n hunh quang cng l mt loi n phng in, tuy nhin bn cht v nguyn l pht

sng hon ton khc vi n phng in nn di gc chiu sng n c xem xt vi t cch l mt chng loi n ring. n hunh quang c hiu sut ln hn n si t t 3 n 5 ln v c tui th ln hn t 10 n 20 ln.

Trc khi pht minh ra bng n hunh quang ngi ta nhn thy : dng in chy qua cht kh hoc kim loi bay hi c th gy ra bc x in t ti nhng bc sng nht nh tu theo thnh phn cu to ho hc v p sut cht kh. Ngoi ra theo nh lut Stoke, khi cho nh sng t ngoi chiu vo cht pht hunh quang th mt phn nng lng ca n bin i thnh nhit, phn cn li bin i thnh nh sng c bc sng di hn nm trong di nh



sng nhn thy c. ng dng hai hin tng ny ngi ta ch to n hunh quang.

Hnh 3.4_ Cu to bng n hunh quang

Kh argon v hi thu ngn

Catot trng bari cacbonat

Git thu ngn ngng ng

Lp bt hunh quang

ng x kh khi ch to

u cc in

Pha bn trong thnh thy tinh ca bng n ngi ta trng mt lp cht bt hunh

quang, ngoi ra ngi ta cn nh vi git thu ngn (khong 12mg) v bm kh tr (thng l kh argon) vo trong ng vi t l thch hp sao cho hin tng ion ho d xy ra. Khi bt n, thu ngn ho hi trc do c in p hai u cc, tip sau l hin tng ion ho cht kh sinh ra tia t ngoi. Tia t ngoi p vo bt hunh quang v pht ra nh sng nhn thy.

Do n hunh quang pht ra tia t ngoi, nu lt ra ngoi s gy nguy him cho s sng nn v bng n c ch to t thy tinh natri cacbonat c tc dng ngn cn tia t ngoi khng cho n pht x ra ngoi.

Bng n hunh quang khi ni vi ngun in th bn thn n khng th t pht sng m phi c b phn khi ng bao gm chn lu (cn gi l ballast) v tc-te (b ngt mch). Da vo bin php khi ng ngi ta chia thnh hai loi : n hunh quang catot nng v catot ngui. Loi catt nng th trc khi pht x electron n phi c nung nng cn loi catot ngui th khng cn nung nng nhng in p t vo n phi ln. Catt l nhng dy tc Vonfam c m bari cacbonat d dng pht x in t. Khi nung nng lp pht x ny khng c nng qu, nu khng tui th ca n s gim xung.

Chn lu l mt cun dy in cm bng st t, khi n khi ng n lm nhim v cung cp nng lng v to ra in p mi rt ln nhng khi n lm vic bnh thng th n c vai tr xc lp im lm vic ca n.

Tc-te thc cht l mt cng tc kiu rle nhit, khi khi ng n ng mch cho dng in chy qua t nng catot ng thi tch lu nng lng t trng cho chn lu. Khi mi n, n m ra lm dng in b gin on v nng lng trong chn lu gii phng di dng xung in p u=Ldi/dt kh ln lm catot pht x electron. V nguyn l th tc m ca tc-te cng b th in p xung to ra cng ln v cng gip n d khi ng.

Chn lu st t bn thn n cng tiu hao nng lng lm cho hiu sut tng ca c b n hunh quang gim xung. Ngoi ra tc-te kiu rle nhit c c tnh khi ng khng tt (v c qun tnh nhit) nn cht lng ca n cng gim v nht l khi in p thp c th khng mi c n. Chn lu st t cn gy ra ting n do c rung ln nn khng thch hp cho mi trng vn phng lm vic. khc phc nhng hn ch ny hin nay ngi ta ch to ra b phn khi ng bng in t (cn gi l chn lu in t). Nguyn l ca chn lu in t l to ra xung in p c tn s rt cao (khong 20 kHz hoc ln hn) nh m in p mi c to ra rt ln, thi gian ngt mch rt b nn c th khi ng ngay c khi in p li in thp.




Cng cn lu thm l loi bng n hunh quang cn c mt s tn gi khc nh n

tuyp, n neon,.. tuy nhin tn gi n neon l tn gi sai v thng thng n khng cha kh neon.

2. Mt s bng n hunh quang thng dng a) Bng n hunh quang thng (T12) y l loi bng n hunh quang c dng ph bin trong dn dng v cng nghip v

n nay n vn chim s lng ln. Tuy nhin trong tng lai ngi ta s thay th bng cc loi n tit kim in hn.

K hiu T12 c xc nh theo ng knh ng l 12/8 inch 38mm Chiu di v cng sut ch to c tiu chun ha nh sau: 2,4 m - 110W ; 1,5 m 65 W ; 1,2 m 40 W ; 0,6 m 20 W b) Bng n hunh quang tit kim in T10-T8-T5:

200 250 300 350 400 450 500 550 600 650 700

Ph kch thch (min t ngoi)

Ph pht x min nhn thy dng Halophotphat Canxi.Bari

lm cht hunh quang

Kch thch

21% nh sng nhn thy

54,2% nhit nng v i lu

24,8% bc x hng ngoi

Hnh 3.5_ Nguyn l, gin nng lng v ph mu bng n hunh quang

Bt hunh quang qut bn trong ng

Electron

in cc pht x electron

Tia cc tm

nh sng nhn thy

Nguyn t thu ngn


Ba loi n ny khc nhau v ng knh : t 10/8 inch vi n T10 n 5/8 inch vi n T5 (cng chnh l k hiu ca n). Ngy nay ngi ta ch c bng T2 nhng cha c s dng ph bin lm.

Hiu sut ca cc loi n ny cng khc nhau. n T5 & T8 cho hiu sut cao hn 5% so vi n T12 v hai loi ny c a chung lp t nhiu hn trong cc h thng chiu sng dn dng v cng nghip.

Trn th trng hin nay xut hin loi T10, T8 ch yu v gi thnh cng cao hn so vi bng T12.

c) Bng n hunh quang compact: Loi n hunh quang compact xut hin gn y m ra mt th trng hon ton mi

ca ngun sng hunh quang. y thc cht l n hunh quang T3 (3/8 inch). Nhng chic n ny cho php thit k b n nh hn nhiu, c th cnh tranh vi loi n nung nng v n hunh quang thng. Vi mt s loi bng n compact tt c th chuyn c 90% nng lng thnh nh sng v ch 10% tn hao nhit v pht tia hng ngoi.

Nhiu ngi cho rng nh sng t n compact yu hn so vi hunh quang thng, l do l n compact pht x nh sng c phn tn ln hn do c nhiu tng xon.

V cu to n c rt nhiu hnh dng khc nhau, thng l hnh trn hoc vung v li c xon thnh nhiu tng. Sn phm bn trn th trng c b iu khin gn lin (CFG) hoc iu khin tch ri (CFN). Tng lai cc loi n ny s c s dng rng ri v nh nc cng c chnh sch tr gi vi n ny. Nh chn lu in t nn hin tng nhp nhy khng cn.

Hnh 3.6_ Cc loi bng n hunh quang compact

3.3 Bng n phng in cng cao (HID) Loi n ny lm vic da trn hin tng phng in h quang nn c gi chung l

n phng in cng cao (hay n HID = Hingh Intentsity Discharge). 1. Cu to ca bng n phng in: a) ng phng in: ng phng in l ni xy ra hin tng h quang in, c ch to bng cht trong

sut hoc trong m v c dng hnh tr. Ngi ta bm vo ng phng in hi thu ngn,



mui kim loi, hay cc loi kh khc to ra hin tng phng in h quang trong cht kh. Phng in h quang bao gi cng to ra nhit lng ln nn ng phng in phi c lm bng vt liu chu nhit rt cao. ng phng in v mt s chi tit khc c t trong mt v thu tinh gi l v bng n.

Khi n ang lm vic, hin tng phng in h quang ang din ra nu c mt s s c (hng chn lu, in p thay i t ngt,) u c th gy n ng phng in v to ra cc mnh v nh c nhit khong 10000C ph hu v bng n v gy nguy him cho ngi i ng, hu hoi ti sn hay ho hon. Do khi ch to b n ny ngi ta phi bao bc n bng vt liu chu c va p v c khng gian ln c th gi li ton b cc mnh v vng ra.

b) V bng n: V bng n thng lm bng thu tinh hoc cc loi vt liu khc nhau nhng chc

nng ca v bng n phi bao gm : - Ngn khng cho khng kh xm nhp lm oxit ho cc chi tit kim loi trong bng n. - n nh nhit lm vic ca n ( h quang khng b t on). - Ngn khng cho tia t ngoi lt ra ngoi lm hu hoi s sng, c bit l n hi thu

ngn to ra kh nhiu tia t ngoi. V bng n thng c dng hnh ellip, c th c dng hnh cu hoc hnh tr. c) Chn lu : Ging nh n hunh quang, n HID cng i hi chn lu mi v n nh im lm

vic. d) ui n : Ch yu l kiu ui xoy, mt s khc c kiu ui gi. e) c im : n HID c nh sng pht ra kh n nh, khng ph thuc nhit mi trng xung

quanh nn rt thch hp cho chiu sng ng ph, qung trng, cng vin, 2. Mt s loi bng n phng in HID thng dng: Khi c phng in ta sng, ty vo loi hi kim loi trong ng m nh sng pht ra c

mu sc khc nhau. Bc x nh sng pht ra l n sc mang c trng ca kim loi (v d natri c mu vng, thu ngn mu vng - xanh dng,). Trong thc t ngi ta ch s dng hai loi hi kim loi l hi thy ngn v hi natri (sodium l tn gi khc ca nguyn t natri, tuy nhin tn gi ny li c dng rt ph bin trong k thut chiu sng).

a) n hi thy ngn p sut cao (HPM: High Pressure Mercury)




n hi thy ngn l kiu n HID c pht minh sm nht trong cc loi n HID. n thu ngn pht ra nh sng phn ln nh s kch thch nguyn t thu ngn. Khi ng phng in h quang nng n s pht ng thi hai loi tia l t ngoi v nh sng nhn thy cc vch vng xanh l cy xanh dng v mt t vch - cam. Nhit mu khong 3000-70000K, ch s hon mu rt thp khong 15-25. Ngi ta thng ph mt lp hunh quang bn ngoi v bng n, nh ci thin c ch s hon mu ln 40-55. Quang hiu ca n cng rt thp, ch 30-65 lm/W.

C l vn quan trng nht lin quan n n hi thy ngn l lm sao thay th chng

bng nhng loi n HID hoc hunh quang c hiu sut v hon mu tt hn. Nhng chic n thu ngn ni chung c hiu sut thp nht trong h n HID, quang thng gim nhanh sau khi a vo s dng.

nh sng do n pht ra trng lnh, khi sng m hay ma th hiu qu chiu sng gim kh nhiu, ngoi ra hi thy ngn rt c, nh sng pht ra c nhiu tia t ngoi nguy him nn hin nay t c dng trong cc d n mi, n ch cn nhng ni lp t trc y.

b) n Metal Halide (cn gi l n phng in Halogen kim loi): n Metal Halide v c bn ging n hi thu ngn nhng ngi ta cho thm vo ng

phng in mui it ca cc kim loi nh indi, thali, natri. V it thuc nhm halogen nn n ny c tn gi l halogen kim loi (Metal Halide).

nh sng pht ra nh s kch thch ca hn hp hi kim loi gm thu ngn v mui halogen kim loi. nh sng c nhit mu khong 4000-60000K v ch s hon mu t 60-93. Quang hiu ca n t 75-125lm/W. nh sng pht ra c mu trng lnh nn khng cn thit phi ph mt lp bt hunh quang ln v bng n. Ph mu nh sng lin tc hn v pht nhiu vch hn so vi n thu ngn

15% nh sng nhn thy

50% nhit v i lu 20%

t ngoi

15% hng ngoi

Gin nng lng

Bt quang

hunh

l

ng phng in

in cc khi ng

Gi

ui n

Khe co gin

in cc chnh V bng n in cc chnh

Khung

Hnh 3.7_Cu to, gin nng lng v ph mu n HID thu ngn

in tr khi ng

400 450 500 550 600 650 700

Mc nng ng



Tuy nhin n ny c nhc im lm gi thnh t, mu sc ca n thay i theo thi gian s dng

c) n hi Natri p sut cao (HPS: High Pressure Sodium) nh sng pht ra nh s kch thch hi natri trong iu kin p sut cao. Cu to ca n

v c bn ging n hi thu ngn. ng phng h quang thng c ch to t gm xit nhm c th chu c nhit ln n 13000C v nu ch to bng thu tinh th natri s tc dng ho hc vi thu tinh lm hng ng phng in. Ngoi hi natri, trong ng phng cn c mt t kh xenon d to ra hin tng phng in (mi ng) hoc cho thm hi thu ngn gim dng in v in p phng in. n hi natri cao p khng c cc in cc khi ng, chn lu m ch c tc-te in t cao p.

Quang hiu kh cao t 120lm/W nhng ch s th hin mu rt km (CRI=20), tui th t 10.000 gi. Khi phng in h quang trong iu kin p sut cao th natri bc x nh sng mu vng - trng vi nhit mu 2000-25000K. Khi phn tch ph mu th n c cc vch vng - xanh l cy - cam v mt t vch - xanh dng.

n hi Natri cao p (HPS) c s dng rng ri trong cc ng dng chiu sng ngoi tri v chiu sng cng nghip, c bit l chiu sng ng ph. Khng nn s dng cho ni c knh ru phong v lm cho c cy c mu a vng. Hiu sut cao l c im u vit hn ca loi n ny so vi n halogen kim loi v nhng chiu sng ng ph khng i hi hon mu cao.

Hnh 3.8_Cu to, gin nng lng v ph mu n Metal Halide

Khe co gin

V bng n

in cc u dy

ui n Gi

Khung

ng phng in

Khung

Np

25% nh sng nhn thy

45% nhit v i lu

10% t

ngoi

20% hngngoi

300 350 400 450 500 550 600 650 700 750

Mc nng

lng



d) n hi Natri p sut thp (LPS: Low Pressure Sodium) n c dng ng tr, i khi hnh ch U,

bn trong c hi natri vi p sut thp khong 10-3mmHg. Ngoi ra d to ra phng in (mi ng) ngi ta cn np mt t kh xenon. Mc in p t 18-180 V. Bnh thng hi natri trng thi ngng t, phi sau vi pht bt n hi natri mi bc ln v pht 2 vch nh sng mu vng - da cam rt nhy cm vi mt ngi (bc sng 555nm). n c quang hiu cao nht trong cc loi n phng in, c th t 190lm/W.

Phn tch ph mu ta thy nh sng gn nh n sc, ch s th hin mu CRI gn bng 0 do LPS thng dng cho nhng ni khng cn cht lng mu tt (nh cu thang) v hn ch s dng cho chiu sng an ninh hoc chiu sng ng ph.

e) n phng in xenon: y l loi n phng in cao p nhng bn trong np kh xenon tinh khit. Khi phng

in, cc nguyn t kh xenon b kch thch ln mc nng lng cao hn, sau tr v trng thi ban u s nh ra photon.

Gi dn in in cc

ng phng in

V bng n

Thu ngn v mui it kim loi

in cc

nh sng 30%

Nhit v i lu 49,5%

Hng ngoi 20%

T ngoi 0,5%

Hnh 3.9_Cu to, gin nng lng v ph mu ca n sodium p sut cao

300 350 400 450 500 550 600 650 700 750

Mc nng

lng

300 350 400 450 500 550 600 650 700 750

Hnh 3.10_ Ph mu n hi Natri p sut thp

Mc nng

lng


n xenon cho nh sng trng xanh gn ging nh sng ban ngy khi tri quang my nn rt tt. Tuy nhin gi thnh rt t khng th dng vo chiu sng cng cng m ch dng cho xe hi cao cp. Gi thnh t l do cng ngh tinh ch cht xenon tinh khit rt t v nu xenon khng tinh khit th khi xy ra phng in s pht n.

u im : tui th cao, cng sng cao hn, tit kim nng lng do khng phi t nng dy tc

nh sng ban ngy khi tri trong

nh sng n phng in Xenon

400 500 600 700 760 Hnh 3.11_ Ph mu n Xenon so vi nh sng ban ngy 3.4 n pht sng quang in (LED: Lighting Emitting Diode) Cu to c bn ca n LED l hai lp bn dn p v n tip xc nhau. Ty cht liu ca p

v n, LED c th pht ra nh sng c mu khc nhau, t xanh l cy, , n trng... Do tiu hao nhit rt t, LED hu nh khng nung nng mi trng xung quanh v khc vi cc loi bng n khc, nh sng LED khng gy chi, mi mt, khng pht ra tia cc tm. Bng vic ghp nhiu LED nh bng ht vi nhau, c th to mt mi trng nh sng rc r trong mt khng gian rng ln, thm ch c th nhit m 300C. Tuy vy, gi thnh LED hin vn cn cao nn Vit Nam n dng cho qung co l ch yu. Cn cc nc khc s dng cho khu du lch, vui chi gii tr, hng nm tit kim c rt nhiu tin in.

V nguyn l: nh sng c to ra khi dng in chy qua nhng cht rn nht nh nh cht bn dn hoc photpho. n LED l loi n mi nht b sung vo danh sch cc ngun sng s dng nng lng hiu qu. Mc d n LED pht ra nh sng di quang ph rt hp (gn nh n sc), chng ta vn c th to ra "nh sng trng bng cch dng n LED xanh c ph photpho hay dng di LED mu -xanh da tri-xanh l cy ho nh sng. n LED c tui th t 40.000 n 100.000 gi ty thuc vo mu sc. n LED c s dng trong nhiu ng dng chiu sng, bao gm bin bo li thot, n tn hiu giao thng v nhiu ng dng trang tr khc. Mc d cn mi m, cng ngh n LED ang pht trin nhanh v ha hn trong tng lai. Ti n tn hiu giao thng, mt th trng th mnh ca LED, tn hiu n bao gm 196 n LED ch tiu th 10W trong khi n nng sng s tiu th 150W. Kh nng tit kim nng lng c tnh khong t 82% n 93%.

Ngoi ra n LED phi hp vi pin mt tri c th to ra h thng chiu sng thn thin vi mi trng, khng tiu th in, tit kim ti nguyn quc gia, gp phn gim pht thi kh nh knh. Tuy nhin y l cng ngh mi, gi thnh u t rt cao nn cn c thi gian thng mi ho.



Hnh 3.12_ Chiu sng bng n LED s dng nng lng mt tri

3.5 n cm ng (n khng in cc)

Lm vic da trn hin tng cm ng in t, khng c

in cc, khng c dy tc. Tui th 60.000 gi, quang hiu c th t 90lm/W. Thng dng trong nhng ng dng c bit quan trng nh n bo khng Bng cm ng c dng cho nhng loi n treo nhng ni rt cao, kh thay, chng hn trn cc thp ln, hi ng, cu treo...

Nguyn l pht sng: T in sn sinh ra t trng, sau t trng sn sinh ra dng in cm ng, ng dng nguyn l dao ng ngu hp a sng in cao tn vo trong bng n chn khng, di tc dng ca bt hunh quang v kh tr to ra hin tng pht sng.

Hnh 3.13_ Hnh dng n khng in cc

3.6 n Sulfua : Ph nh sng ban ngy

khi tri nhiu my

Ph mu ca n sulfua

Hnh 3.14_ Hnh dng v ph mu n Sulfua so vi nh sng ban ngy



n ny cng khng c in cc, nh sng pht ra do bc x ca cc nguyn t sulfua trong mi trng kh argon b kch thch bng vi sng. n c quang hiu rt cao, c 100lm/W v bc x rt t tia hng ngoi cng nh t ngoi. Nhit mu c th ln ti 60000K gn vi nh sng ban ngy v ch s hon mu CRI=80. Khi phn tch ph mu n sulfua ngi ta thy n gn trng vi ph mu ca nh sng ban ngy (khi tri nhiu my).

Bng thng s k thut ca cc loi n thng dng

(Theo s liu do hng Schrder cung cp nm 2006)

Cng sut (W) Tui th Cht lng mu Kch Gi Loi n T n

Lm/W(gi) T(K) Hon mu thc thnh

Si t 15 200 10 1.000 3000 100 Nh t Si t-Halogen 50 2.000 20 2.000 3000 100 Nh t Hunh quang 8 58 90 15.000 Thay i 85 Di t Cao p thy ngn 50 1.000 55 12.000 3800 45 Ln t Cao p Metal Halide 35 150 85 8.000 4000 85 Nh t Cao p Metal Halide 250 400 85 12.000 4000 65 Nh t Thp p Sodium 18 131 200 15.000 1800 - Di t Cao p Sodium 35 1.000 120 20.000 2000 25-85 Nh t Cm ng 55 180 70 60.000 3-4000 80 Ln t

LED 0,07 1,2 15 10.000100.000 Nhiu loi Nhiu loi Nh t

Bng tm tt phm vi s dng ph bin ca cc loi n

Loi n ng dng c trng

Si t Gia nh, khch sn, chiu sng chung, chiu sng khn cp.

Hunh quang Vn phng, ca hng, bnh vin, gia nh Hunh quang compact Khch sn, ca hng, gia nh, vn phng

Thy ngn cao p HPM Chiu sng chung trong nh my, ga ra, xe, chiu sng bng n pha

Metal halide MH Trng by, chiu sng bng n pha, khu trin lm sn vn ng, cng vin, vn hoa, khu vc xy dng, sn th thao, pht truyn hnh mu

Hi Natri cao p HPS Chiu sng chung trong nh my, kho hng, ng ph

Hi Natri h p LPS Lng ng, ng hm, knh, n ng, cu thang c yu cu khng cao v th hin mu.



CHNG 4 CU TO CA B N CHIU SNG CNG CNG

Trong chng trc chng ta nghin cu v ngun sng l ni pht ra nh sng. Tuy

nhin ch c mi ngun sng th khng th ng dng c trong chiu sng cng cng cng nh cc mc ch chiu sng khc. Do vy ngi ta cn phi s dng cc b phn khc nh b linh kin in mi cho n lm vic, b phn phn quang iu khin nh sng n ng i tng cn chiu sng, knh bo v chng m, chng sng m, chng n, ni chung l b n c y ba thnh phn : in - c - quang hc.

Cc b phn ni trn khi lp rp hon chnh gi l b n hoc cho n (theo Quyt nh s 13/2008/Q-BCT ca B Cng Thng) . C th ni ngun sng chnh l tri tim ca b n. Do nhng u im ni tri ca n phng in khi s dng cho chiu sng ng giao thng, chiu sng cc khu vc cng cng trong th m hin nay n phng in HID l ngun sng c s dng ch yu. Trong chng ny ta s nghin cu v cc thnh phn c bn cu to nn b n phng in HID..

4.1. Cu to chung ca mt b n chiu sng cng cng ng cng

1

2

1

2

4

3

5

6

7

8

9

10

1. u dy in vo n 2. Tm lp linh kin in c th tho ri 3. L lp cn n 4. L ui n lp ngun sng (iu chnh c) 5. Rong cao su lm kn 6. Knh bo v (thy tinh hoc nha) 7. Bn l bng thp khng g 8. Tm phn quang m nhm bng phng php ha hi. 9. V n c 2 ngn (linh kin in v quang hc) 10. Np bo v ngn in

Mt trc mt b n

Hnh 4.1_ Cu to b n chiu sng cng cng



V hnh dng, mi hng ch to n c mt kiu dng khc nhau tuy nhin u c cc b phn c bn nh trn. Mi b n u c th lp c nhiu loi ngun sng khc nhau v tng thch vi nhiu cng sut khc nhau. iu ny cho php chuyn bit ho trong sn xut : b n ca hng ny c th lp ngun sng ca hng kia, do n cng cho php thay th d dng.

4.2. Cc b phn chnh ca b n chiu sng cng cng

1. Tm phn quang Cc loi n chiu sng cng cng thng c tm phn quang phn b li nh sng

ca ngun sng bng cch ng dng nh lut phn x u. Nhim v ca n l iu khin nh sng pht ra ph hp vi mc ch s dng.

Tm phn quang c th c lm bng gng hoc c m mu trng (m nhm hoc bc), mc ch chnh l tng h s phn x u r. H s ny c th t 0,85 (i vi gng) n 0,93 (trng bc). Trong thc t, tm phn quang thng m bng nhm tinh cht theo phng php bay hi, va gim c gi thnh so vi m bc m vn m bo h s r kh cao. Theo quy nh trong tiu chun Vit Nam TCVN5828-1994 i vi n ng ph th h s phn quang ban u phi 0,8.

Ch

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