ED siêu sáng nguồn sáng của hiện tại và tương lai

CONG NGHE QNG DUNG

Trong thap nien dau cua the ky 2 1 , LED (Light Emitting Diode - Oidt phat quang) co sir phat trien
vircft bac. Vol UU diem ctf ban la than thien mdi trtftfng, khdng sir dung hoa chat doc hai, khdng
gay hieu ting nha kinh, co do ben ctf hoc cao va dac biet t u o i tho rat cao nen LED dang dan thay
the den huynh quang trong chieu sang noi t h a t . Nhieu t o hop ma tran LED da da dtftfc ting dung
trong chieu sang dtftfng giao t h o n g . Dac biet trong chieu sang trang t r i , quang cao va le hoi LED
t o ra Uu diem vtftft t r d i so voi cac nguon sang kinh dien va dang la cac thanh phan chi'nh trong
chieu sang cac cdng t r i n h kien true. Bai viet sau day diem qua cac thanh t t f u trong linh vtfc nay.

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PGS. LE VAN DOANH - KS. LE TRUNG KIEN
Tri/gngDHBKHa

SUPER B R I G H T LED, L I G H T SOURCE OF PRESENT A N D FUTURE
In the first decade of the 21st century, LEDs (Light
Emitting Diode) have a great development. Because of
its basic advantages as harmony with environment,
non-toxic chemical, no greenhouse effect, high mechanical strength and longevity, LEDs are gradually replacing fluorescent lamps in interior light. A lot of LEDs
matrix combination has already been used in road lighting. Especially in decoration, advertisement and festival, LEDs show outstanding advantages compared to
other classical sources of light and are the main ingredient in building illumination
12

Tir ddng hoa ngay nay / 12. 2010

SO L U O C VE CAC N G U O N S A N G
Thdi dai anh sang dien bat dau t d den spi dot cua
Thomas Edison (1837-1931) che tao vao nam 1879 tdso

cac bon, tao nen nhiet dp 3900 K, hieu qua anh sang 2
lm/W,tuoi thp 600 gid. Nam 1908 nha khoa hoc Ddc Em:
Werner Siemens (1816-1902) da sd dung soi dot vonfram-nicken keo dai tuoi tho cua den soi dot. Cac den soi
dot hien dai trong mdi trudng halogen co chi so the hien
mau xap xi 100, cho anh sang am va dat hieu qua 20
Im/W.
Ho quang thuy ngan dupe phat hien t d nam 1901
nhung 30 nam sau mdi dupe dng dung trong thpc te.Tu
nam 1960 cac den phong dien thuy ngan mdi dupe dng


dung trong chieu sang cong cong, chung co the chuyen
hoa 20% dien nang thanh quang nang va la nguon sang
lanh.
Hien tuong ion hoa phat sang trong chat khi dupe
nha khoa hpc Anh Edward Townsend (1868-1957) phat
hien da dupe dng dung de che tao cac loai den phdng
dien. Den hoi Natri (Sodium) ap suat thap do Van
Voorhir che tao t d nam 1923 cho anh sang don sac mau
vang, chung co the chuyen hoa 80% dien nang thanh
quang nang, vi vay co hieu qua anh sang rat cao, dat tdi
200 Im/W, nhUng he so the hien mau rat thap, gan bang
khdng. Den Sodium ap suat cao co the chuyen hda 50 %
dien nang thanh quang nang, cho anh sang gan voi
mau trang hon, hieu qua anh sang dat tdi 120 Im/W, chu
yeu dung cho chieu sang cdng cdng.
Nam 1933 cac den dng huynh quang dau tien da
dupe ban ra thi trudng va ngay nay da trd thanh nguon
sang chu yeu, dupe sd dung rpng rai de chieu sang
trong nha. Cac den huynh quang the he mdi co hieu qua

anh sang tdi 80 Im/W, chi so the hien mau 70-85.
Cac den halogen kirn loai (Metal halide) do cdng ty
General Electric che tao t d nhPng nam 1960, cd hieu
suat sang khong IPn hon den Sodium ap suat cao,
nhung cd anh sang trang hon va dugc Png dung rpng
rai trong chieu sang cdng cpng, chung cd the dupe che
tao vdi cdng suat IPn co 2 kW, hieu qua sang dat tdi 95
Im/W, thich hpp cho chieu sang cac cong trinh van hoa,
the thao.
Co khoang tren 6000 loai den khac nhau va dupe
phan chia thanh 3 nhom chinh:
• Den spi dot va spi dot halogen. Day la nguon sang
don gian, sd dung thuan tien, cd he so the hien mau rat
cao CRI = 100. Tuy nhien hieu qua nang lupng thap, tuoi
thp thap nen cd xu hudng bi loai bd
• Den phdng dien trong chat khi trong dd cd den
huynh quang, den thuy ngan cao ap, den Metal Halide,
den Sodium ap suat cao va ap suat thap. Day la cac den
dupe sd dung rpng rai trong chieu sang ndi that va
ngoai that hien nay.
• LED nguon sang ban dan.. LED ra ddi t d nhung nam
60 cua the ky trudc, dupe dng dung de hien thi thoi gian
cua ddng hd bao thdc hay dung lupng pin cua may ghi
hinh thong qua anh sang dd, xanh la cay, vang ma chua
cd mau traing.
Nam 1993, Cdng ty Hda chat Nichia cua Nhat Ban da
nghien cdu hoan chinh cdng nghe che tao loai den LED
cho anh sang trang. LED dpa tren cdng nghe ban dan.
Hien tai, LED cho anh sang trang cd tudi thp toi 50 nghin
gid sd dung, gap 50 lan so vdi bong den 60 W thong

thudng. LED se thay the dan den spi dot va den huynh
quang bdi nhUng Uu diem nhutiet kiem nang lupng tieu
thu t d 70 den 80% so vdi loai den thong thudng; tudi
tho cao; kich cd nhd; nhiet nang sinh ra trong qua trinh
hoat ddng khong dang ke; hoat dpng tot trong dieu

kien nhiet dp thap; sd dung ddng dien mpt chieu vdi
hieu dien the nho; khdng gay d nhiem mdi trUdng vi
khdng sinh ra tia cue tim, khdng cd thuy ngan...
Bieu do hieu suat Lumen/Watt cua cac loai den
Den day toe
Halogen 20K

|
m

Halogen lOK
Halogen
thuong mai
Den huynh
quang T5/T8
Den LED loai
tot nhat
0

1

20

40

GO

80

100

120

Hinh 1 So sanh hieu suat cac loai den
So sanh hieu suat cac loai den dupe cho trong hinh 1.
Ta nhan thay bat dau t d nam 2000 cac den LED sieu
sang co dac tinh quang va chi tieu nang lupng tuong
duong vdi den huynh quang
2. NGUYEN LY LAM VIEC CUA LED
Phan chu yeu cua mpt chip LED la tinh the ban dan
InGaN tao nen chuyen tiep p-n , dupe ddng goi voi chan
ndi va thau kinh (hinh 2). Khi dat dien ap nhd len chuyen
tiep se tao nen cac dien tich di ddng chay qua chuyen
tiep va bien ddi nang lupng d u thanh anh sang.
Nang lupng do sptai hpp dien t d Id trdng giai phong
se phat sinh cac photon. Tren hinh 3 cac dien t d dupe
bieu dien bang vdng nhd mau xanh, cdn Id trdng bang
mau do. Khi dat vao dien trUdng chung chuyen dpng va
tai hpp trong vung chuyen tiep con gpi la vung ngheo.
Sp chuyen mdc nang lupng cua cac hat giai phdng photon va phat ra anh sang. Budc song bde xa, nghia la mau
cua LED phu thupc vao vat lieu cua Idp chuyen tiep nay.
Quang thong do LED phat ra chi nam trong dai hep

Hinh 2 Cau tao cua LED

Automation Today / 12, 2010


De md rpng pho mau cua LED ngUPi ta sddung phot
pho dupe kich thich bang LED, chung phat mau da trai.

Chat cho

Cnat nh

hieu qua tuong t u den dng huynh quang.
Hinh 7 la den chieu sang ngd xdm do cdng ty chieu

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n

Hinh 5 Den ong LED
sang Da N l n g che tao.
0„OO0fllO 0~«* o o 8„0 o
° o ° o W ° °S* • ; • o p W o V
n n n n rr o n
•
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|4— Vung ngheo
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0

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H/nh 3 Nguyen ly hoat dong cua LED

3. LED SIEU SANG MAU TRANG
De tao nen LED mau trang ta co the thpc hien theo 2
cong nghe:
• Sddung phot pho hap thu anh sang xanh va hoi phat
thanh anh sang trang. Tren hinh 4a la LED sieu sang mau
trang dupe tao bdi LED xanh co phu phot pho. Hinh 4b la
anh sang do LED nay tao ra, co the dat nhiet dp mau 5000K
va CRI = 90, cong suat moi chip co the len toi 5 W, hieu qua
nang lupng thong thuong 60 Im/W, co the dat toi 150 Im/W
trong phong thi nghiem.

(a)

( b)

4) CHIEU S A N G T R A N G TRI B A N G LED
Sd dung LED trong chieu sang trang tri cd Uu diem
vupt trpi so vdi cac nguon sang truyen thong do LED co
kich thudc nhd, dp ben co cao, cd the tao nen hang trieu
mau t d viec phdi hpp cac LED 3 mau co ban R (Red), G
(Green), B(Blue). Trong chieu sang le hdi 1000 nam Thang

Long, cdng ty Chieu sang do thi Ha Ndi (H APULICO) da sd
dung nhieu logo hinh rdng, de quat, bieu tupng Ha
Ndi... tao nen anh sang mau lung linh vdi nhieu kich
ban khac nhau. Hinh 8 la mdt so mau chieu sang 1000
nam Thang Long.

5) MOT SO LTNG DUNG CHINH CUA LED:

Hinh 4 Tao nen LED trdng (b) bdng each phu photpho (a) ten LED xanh • Sd dung trong chieu sang chieu sang cdng cpng,
chieu sang trong cac toa nha va hp gia dinh.
• Sd dung lam bp phan hien thi trong cac thiet bi dien,
• Bo tri LED do (a), da trdi (b) va xanh la cay (c) gan nhau,
chung hoa mau va tao nen mau trang (d). Hien nay LED mau
dien td, den quang cao, trang tri, den giao thong.
do va da cam co hieu suat sang 17-23 Im/W, cao hon den spi
• Cac LED phat ra tia hong ngoai dupe dung trong
dot mot chut nhUng van kem xa cac den phong dien.
cac thiet bi dieu khien t d xa cho do dien t d dan dung..
Sd dung lam den xe, den dudng, den ham mo, den
chieu hau cho man hinh cua dien thoai cam tay, den
chieu hau cho man hinh tinh the long (LCD), in an ky
thuat so....

a) b) c) d)
Hinh 4 Tao nen LED mau trdng tif LED do, xanh, lo
De tang cong suat cua nguon sang nguoi ta sd dung
ma tran LED gdm cac chip LED dupe mac ndi tiep va
song song.
Hinh 5 la den dng gdm cac chip LED mac ndi tiep cd
14 Tu dong hda ngay nay / 12, 2010

• L/ng dung rdng rai tren cac ITnh vpc: bang quang
cao ngoai trdi, bang quang bao, ddng hd cd Idn dat tai
cac bien quang cao tarn Ion tren duong cao tdc, he
thong den giao thong, bien chi dan, va cac san pham
khac nhu bang chay chu dien td, bang he thong gid,
Bang ty gia, bang chdng khoan, he thong xep hang tii
dpng...
• LED co the duoc sd dung trong nhieu ITnh vpc nhu"
den doc, chieu sang be boi, nhat la cho chieu sang


Tong chieu dai la 40m, trong do moi con Rong co kich thudc 16m, logo Ha Npi duong kinh la 5.5m.
Toan bp khung gian se dupe gia co bdi cot thep bpc inox, each mat dat 5m.

Hinh 8 Chieu sang le hpi WOO nam Thang Long bang LED
quang cao ngoai trdi tai nhung noi kho thay lap, do co
tuoi thp cao hon nhieu lan so vdi bong den ne-dng,
dong thdi co nhieu mau sac phong phu nhU: do, xanh la,
xanh da trdi, mau ho phach... Tren thpc te Cong ty
Electric General va Might Technologies of Evanston III da
tao ra cac bien quang cao bang den LED rpc ro nhu den
ne-ong.
• Mpt dac diem khac cua LED la it tieu hao nang
lupng va khong nong. Bong den truyen thong, den
neon, den halogen... deu can tP 110-220 V moi chay
dupe, trong khi den LED trang chi can tP 3-24 V de phat
sang. Phan chia thi trUdng LED nam 2008 dupe cho tren
hinh 9

Hinh 9 Phan chia thi trUdng LED
dien t d cd be day phat trien va co the manh tren thi
trudng. Dan dau la tap doan chieu sang so 1 Philips vPi
164 sang che, t h d hai la Cree Inc vdi 33 sang che. Mpt so
tap doan dien t d khac cung da ghi ten minh tren ban do
sang che la Gelcore LLC (28), Osram (27), Siemens (23),
Samsung (20), LG (17), Univ (15).
d Viet Nam nhieu cdng ty che tao thiet bi chieu sang
nhU Rang Ddng, Dien Quang, TrUdng DHBK Ha Ndi va
nhieu cdng ty khac da trien khai nghien cdu va che tao
nhieu chung loai LED. Khd khan chinh cua LED la tan
nhiet khi tang cdng suat LED.G

Phan chia thi truong LED, 2008
6) TLTONG LAI CUA LED
LED dang phat trien rat nhanh va dang canh tranh
vPi cac den truyen thong trong nhieu Png dung. Trong
tuong lai gan cac LED se hoan toan thang the va la
nguon sang cua tuong lai. TP nam 1974 den nay (thang
10/2009) co 2.272 sang che ve LED. Nhin ban do sang
che cua LED qua cac nam, co the nhan thay con dudng
phat trien cua cong nghe LED chia lam 2 chang ro ret. TP
nhung nam 2000 trd ve truoc, sang che LED chi ddng d
con sd hang chuc thi t d nam 2000 den nay, so lupng
sang che ve LED tang vqt, dat den con so hang tram. Cac
cdng ty sd huu cac sang che LED chinh la cac cdng ty

Automation Today / 12, 2010