Fa'ata'ita'iga o Fesili e Talanoaina ai Diodes e Fa'asalalauina Malamalama (LEDs)
O le light-emitting diode (LED) o se masini semiconductor e faʻasalalauina le malamalama pe a tafe atu se eletise i totonu. O le mea e tupu i tua atu o LED e taʻua o le electroluminescence, lea e faʻasalalauina ai e se mea semiconductor le malamalama pe a faʻaosofia e se eletise. Ua lauiloa tele LED i le tele o faʻaoga ona o lo latou lelei tele ma le umi o le ola pe a faʻatusatusa i puna malamalama masani e pei o moli incandescent.
I totonu o lenei tusiga, o le a matou talanoaina ai nisi o faʻataʻitaʻiga o faʻafitauli e fesoʻotaʻi ma LEDs ma faʻamatalaina auiliili a latou fofo ma talanoaga e fesoasoani ai e malamalama i le manatu i tua atu o lenei mea.
Faʻataʻitaʻiga Fesili 1: Uiga Autu o LEDs
Fesili: O se LED e iai le gafatia e fa'asalalauina ai le malamalama ma se galu e 650 nm (nanometers). Fuafua le malosi o photons e fa'asalalauina e lenei LED i electron-volts (eV).
Talanoaga:
E mafai ona fuafuaina le malosiaga o le photon e faʻaaoga ai le fuafuaga a Planck:
\[ E = \frac{hc}{\lambda} \]
di mana:
– \( E \) o le malosiaga o le photon,
– \( h \) o le tumau a Planck (\(6.626 \times 10^{-34} \text{ Js}\)),
– \( c \) o le saoasaoa o le malamalama (\(3 \times 10^8 \text{ m/s}\)),
– \( \lambda \) o le galu o le malamalama (650 nm po'o le \(650 \times 10^{-9} \text{ m}\)).
O le suiina o nei tau i totonu o le fua fa'atatau e maua ai:
\[
E = \frac{6.626 \times 10^{-34} \times 3 \times 10^8}{650 \times 10^{-9}}
= \frac{1.9878 \times 10^{-25}}{650 \times 10^{-9}}
= 3.05 \times 10^{-19} \text{ J}
\]
Sosoo ai, matou te liua Joules i electron-volts e faʻaaoga ai le liua \(1 \text{ eV} = 1.602 \times 10^{-19} \text{ J}\):
\[
E = \frac{3.05 \times 10^{-19}}{1.602 \times 10^{-19}}
≈ 1.90 \text{ eV}
\]
O lea la, o le malosiaga o le photon e faʻasalalauina e se LED e iai lona galu e 650 nm e tusa ma le 1.90 eV.
Faataitaiga 2: Voltage Fa'asolo i Luma LED
Fesili: O le LED mumu e iai le voltage i luma e 2V ma e manaʻomia se tafe eletise e 20 mA e galue lelei ai. Faʻatatau le malosiaga e faʻaaogaina e le LED.
Talanoaga:
Mo le fuafuaina o le malosiaga e mitiia e le LED, matou te faʻaaogaina le fua faʻatatau mo le malosiaga, e pei o:
\[ P = V \times I \]
di mana:
– \( P \) o le malosiaga i Watts (W),
– \( V \) o le voltage i Volts (V),
– \( I \) o le tafe o le eletise i Amperes (A).
Sui nei tau i totonu o le fua fa'atatau:
\[
P = 2 \text{ V} \times 20 \text{ mA}
= 2 \text{ V} \times 0.02 \text{ A}
= 0.04 \text{ W}
\]
O lea la, o le malosiaga e mitiia e se LED mumu o loʻo faʻagaoioia i se voltage i luma o le 2V ma se tafe o le 20 mA e 0.04 Watts.
Faʻataʻitaʻiga 3: Lelei o le LED
Fesili: O le eletise lanumoana LED e 30% lona lelei fa'akoanuti. Afai e fa'aogaina e le LED le 0.1 W o le eletise, o le a le tele o le eletise e fa'asalalauina o se malamalama?
Talanoaga:
O le quantum efficiency (η) o le fua faatatau lea o le malosiaga e faʻasaʻolotoina i le tulaga o le malamalama (P_luminous) i le malosiaga eletise e ulufale mai (P_input):
\[ η = \frac{P_{\text{luminous}}}{P_{\text{input}}} \]
Mo le sailia o le \( P_{\text{luminous}} \), fa'aaoga le fua fa'atatau lea ma se tau aoga e 30% pe 0.30:
\[
0.30 = \frac{P_{\text{luminous}}}{0.1 \text{ W}}
\]
O lea la:
\[
P_{\text{luminous}} = 0.30 \times 0.1 \text{ W}
= 0.03 \text{ W}
\]
O lea la, o le malosiaga e faʻasaʻolotoina e le LED i le tulaga o le malamalama e 0.03 Watt.
Faʻataʻitaʻiga Faʻafitauli 4: Matāgaluega LED Faʻasolosolo
Fesili: E tolu au LED e 2V le voltage i luma e manaʻomia ona faʻapipiʻi faʻasolosolo. Afai o le puna o le voltage e 9V, fuafua le tau o le resistor e manaʻomia e faʻatapulaʻa ai le tafe eletise i le 20 mA.
Talanoaga:
A fa'apipi'i fa'asolosolo LEDs, o le aofa'i atoa o le voltage e mana'omia o le aofa'i lea o voltage i luma o LED ta'itasi:
\[
V__ {total} = V_f1 + V_f2 + V_f3
= 2V + 2V + 2V
= 6V
\]
O le voltage totoe e tatau ona faʻataʻapeʻapeina e le resistor o le:
\[
V_{R} = V_{puna} – V_{aofa'i}
= 9V – 6V
= 3V
\]
Faatasi ai ma se tafega manaʻomia o le 20 mA, o le tau o le resistor e fuafuaina e faʻaaoga ai le Tulafono a Ohm:
\[
R = \frac{V_{R}}{I}
= \frac{3V}{20 \text{ mA}}
= \frac{3V}{0.02A}
= 150 \Omega
\]
O lea la, o le tau o le resistor e manaʻomia e 150 ohms.
Faataitaiga 5: Matagaluega Faagata Taimi Faalava o le LED
Fesili: I totonu o se matagaluega, e lua LED o loʻo faʻatasi, e tofu ma le voltage i luma e 2V ma le tafe o le eletise e 20 mA. O le a le aofaʻi o le tafe e manaʻomia mai se puna voltage 5V pe afai e faʻaaogaina se resistor mo LED taʻitasi?
Talanoaga:
Mo LED o loʻo faʻatulagaina faʻatasi, o LED taʻitasi o le a maua le voltage tutusa, o lona uiga o latou voltage i luma, ma talu ai latou te manaʻomia le 20 mA o le eletise i le LED taʻitasi, o le aofaʻi atoa o le eletise e:
\[
I_{aofa'i} = I_1 + I_2
= 20 \text{ mA} + 20 \text{ mA}
= 40 mA
\]
Mo le fuafuaina o le tau o le resistor mo LED taitasi:
\[
V_{R} = V_{puna} – V_f
= 5V – 2V
= 3V
\]
O le taua o le resistor e faʻatapulaʻa ai le tafe i totonu o LED taʻitasi o le:
\[
R = \frac{V_{R}}{I}
= \frac{3V}{20 \text{ mA}}
= \frac{3V}{0.02A}
= 150 \Omega
\]
O lea la, e manaʻomia e LED taʻitasi se resistor e 150 ohm. O le aofaʻi atoa o le eletise e manaʻomia mai se sapalai eletise 5V e 40 mA.
I'uga
O LED o ni vaega taua i mea fa'aeletoronika fa'aonaponei ona o lo latou gafatia e tu'uina atu ai moli e matua'i lelei ma umi le ola. O le malamalama i manatu fa'avae e pei o le voltage i luma, tafega, malosiaga, quantum efficiency, ma le auala e fa'atulaga ai i latou i se matagaluega o le a maua ai se fa'avae mautu mo fa'aoga aoga. O fa'ata'ita'iga o lo'o i luga o se la'asaga muamua lea agai i le fa'atautaia o fa'aoga eseese ma fa'atusatusaga e feso'ota'i ma le fa'aaogaina o LED i matagaluega fa'aeletoronika.
