Mfundo Yogwirira Ntchito ya Photodiodes ndi Phototransistors
Kukula kwa ukadaulo wamakono wamagetsi kumadalira kwambiri zida zoyezera zomwe zimatha "kuwona" kuwala ndikukusintha kukhala zizindikiro zamagetsi. Zigawo ziwiri zomwe zimagwiritsidwa ntchito kwambiri pa izi ndi ma photodiode ndi ma phototransistors. Zonsezi ndi za m'gulu la ma semiconductors omwe amamva kuwala, omwe amagwiritsidwa ntchito kwambiri mu machitidwe odziyimira pawokha, kulumikizana kwa kuwala, zida zoyezera, ndi zida zamakasitomala monga zowongolera kutali, osindikiza, ndi masensa a kuwala m'mafoni am'manja. Ngakhale kuti zonse zimayankha kuwala, ma photodiode ndi ma phototransistors ali ndi mfundo zosiyanasiyana zogwirira ntchito, makhalidwe, ndi ntchito. Nkhaniyi ikufotokoza mozama mfundo zawo zogwirira ntchito, kuziyerekeza, ndikupereka zitsanzo za momwe amagwiritsidwira ntchito.
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1. Zoyambira pa Kuzindikira Kuwala mu Semiconductors
Kuti timvetse ma photodiode ndi ma phototransistors, tiyenera kukumbukira lingaliro lofunika la ma semiconductor: ma charge carriers, ma electron ndi mabowo. Kuwala (ma photon) kukagunda chinthu cha semiconductor, kumapatsa mphamvu ma electron, zomwe zimapangitsa kuti asunthe kuchoka pa valence band kupita ku conduction band. Njirayi imapanga ma electron-hole pairs. Ma photon akamayamwa kwambiri, ma charge carrier pairs ambiri amapangidwa, zomwe zimawonjezera kuchuluka kwa mphamvu yomwe imatha kuyenda.
Mfundo yofunika kwambiri ndi yakuti: kuwala kumayambitsa kusintha kwa mphamvu zamagetsi za zigawo. Kusintha kumeneku kungakhale ngati kuwonjezeka kwa mphamvu zamagetsi, kuchepa kwa kukana, kapena kuwoneka kwa magetsi. Mu ma photodiode ndi ma phototransistors, kusintha kwakukulu kumawonekera mu mphamvu zamagetsi.
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2. Mfundo Yogwirira Ntchito ya Photodiode
a. Kapangidwe ndi Njira Yogwirira Ntchito
Photodiode kwenikweni ndi PN diode (kapena mitundu yosiyanasiyana monga PIN ndi avalanches photodiodes) yopangidwa kuti ikhale yogwirizana ndi kuwala. Kapangidwe ka PN kamapanga dera lochepa, dera lopanda zonyamulira zaulere zomwe zimagwira ntchito ngati "malo olekanitsa" omwe ali ndi mphamvu.
Ma Photodiode amatha kugwira ntchito m'njira zingapo, koma zomwe zimagwiritsidwa ntchito kwambiri ndi izi:
1. Njira yowongolera kuwala (kutengera m'mbuyo)
Photodiode imakhala yosiyana ndi ina iliyonse. Dera lochepa limakula, yankho limakhala lachangu, mphamvu yamagetsi imachepa, ndipo kulumikizana nthawi zambiri kumakhala bwino. Njira imeneyi ndi yofala kwambiri pa masensa ndi kulumikizana kwa kuwala.
2. Mawonekedwe a Photovoltaic (opanda tsankho/zopanda tsankho)
Ma Photodiode sali ndi mbali yakunja. Kuwala komwe kumabwera kumapanga magetsi ofanana ndi selo ya dzuwa, ngakhale kuti ndi yaying'ono. Izi zili ndi ubwino wokhala ndi phokoso lochepa, zomwe zimapangitsa kuti likhale loyenera kuyeza zinazake, koma yankho likhoza kukhala lochedwa kuposa mbali ya reverse bias.
b. Njira Yosinthira Kuwala Kukhala Mphamvu
Pamene photodiode ikuwonetsedwa ku kuwala:
1. Ma photon amatengedwa m'dera lomwe lachepa kapena pafupi ndi malo olumikizirana.
2. Peyala ya ma elekitironi ndi mabowo imapangidwa.
3. Mphamvu yamagetsi yamkati yomwe ili pamalo olumikizirana magetsi imalekanitsa awiriwa:
- Ma electron amakankhidwira kumbali ya N
- Dzenje likankhidwira kumbali ya P
4. Kulekanitsa mphamvu kumeneku kumapanga photocurrent.
Kutuluka konse nthawi zambiri kumakhala kophatikizana ndi:
– Mphepo yamdima: mphamvu yaying'ono yomwe imayenda ngakhale popanda kuwala (chifukwa cha kutentha).
– Mphamvu ya Photocurrent: mphamvu yamagetsi yomwe imagwirizana ndi mphamvu ya kuwala.
Mwachidule, kuwala kukakhala kowala kwambiri → kuwala kwa dzuwa kumakhala kwakukulu.
c. Makhalidwe a Photodiode
Zina mwa makhalidwe ofunikira a photodiode ndi awa:
- Yankho lachangu (loyenera ma signali othamanga kwambiri)
- Mphamvu yowala yolunjika kuchokera ku kuwala kupita ku mtundu wina
– Mphamvu yotulutsa ndi yochepa poyerekeza ndi phototransistor, kotero nthawi zambiri imafuna amplifier (op-amp/transimpedance amplifier)
- Phokoso ndi mdima ndi zinthu zofunika kwambiri pakugwiritsa ntchito molondola.
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3. Mfundo Yogwirira Ntchito ya Phototransistor
a. Kapangidwe Koyambira ka Phototransistor
Phototransistor kwenikweni ndi transistor ya BJT (nthawi zambiri NPN) yomwe maziko ake amapangidwa kuti azitha kuwunikira. Mu phototransistor, kuwala kumagwira ntchito ngati "base current" yomwe imalamulira collector-emitter current.
Mosiyana ndi ma photodiode, omwe amapanga mphamvu mwachindunji kuchokera ku photon effect, ma phototransistors amagwiritsa ntchito mphamvu ya transistor. Chifukwa cha mphamvu ya phototransistor, mphamvu ya phototransistor ikhoza kukhala yayikulu kwambiri.
b. Njira Yogwirira Ntchito: Yopepuka ngati Cholowa M'malo mwa Mphamvu Yoyambira
Momwe imagwirira ntchito ingafotokozedwe motere:
1. Kuwala kumagunda malo oyambira-osonkhanitsa (nthawi zambiri malo olumikizirana a BC).
2. Mawiri a ma elekitironi ndi mabowo amapangidwa chifukwa cha kuyamwa kwa photon.
3. Izi zimapangitsa kuti mphamvu yamagetsi yaing'ono ikhale yofanana ndi mphamvu yamagetsi ya photo base.
4. Mu transistor ya BJT, mphamvu yosonkhanitsa ndi pafupifupi:
\[
I_C \pafupifupi \beta \cdot I_B
\]
Popeza \( I_B \) "imapangidwa" ndi kuwala, kuwala kudzalamulira \( I_C \).
Zotsatira zake, kusintha pang'ono kwa mphamvu ya kuwala kungayambitse kusintha kwakukulu kwa mphamvu ya collector kuposa mu photodiode, chifukwa cha gain factor \(\beta\).
c. Njira Yoyendetsera Dera ndi Kukhazikitsa
Ma Phototransistors nthawi zambiri amagwiritsidwa ntchito m'njira zotsatirazi:
– Chotulutsa chofala: chosonkhanitsa magetsi kupita ku magetsi kudzera mu resistor, chotulutsa magetsi pa chosonkhanitsa. Chikayikidwa pa kuwala, transistor imakhala "YOWANI" kwambiri, magetsi otulutsa magetsi amasintha.
– Wosonkhanitsa wamba (wotsatira wotumiza): chotulutsa pa emitter, chothandiza pa zinazake koma chosakhala chofala kwambiri m'masensa osavuta.
Nthawi zina ma phototransistors amachotsa pini yoyambira (3-pin), koma ambiri amakhala ndi pini ziwiri zokha (mkati mwake simungapezeke).
d. Makhalidwe a Phototransistors
- Yosavuta kugwiritsa ntchito (mphamvu yotulutsa mphamvu zambiri)
- Yocheperako kuposa ma photodiode chifukwa cha njira yosungiramo mphamvu ndi mphamvu za transistor
- Nthawi zina zimakhala zochepa kwambiri, makamaka pafupi ndi kuchuluka kwa madzi.
- Yoyenera kuzindikira kuwala/mdima, kuzindikira zinthu, ma optocouplers, ma revolution counters, ndi ntchito zosavuta zowongolera.
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4. Kuyerekeza kwa Photodiode ndi Phototransistor
Nayi chidule cha kusiyana kwakukulu:
1. Liwiro la kuyankha
– Photodiode: yachangu kwambiri (yabwino kwambiri polumikizirana ndi kuwala, kusintha kwachangu)
– Phototransistor: yocheperako (yokwanira masensa wamba)
2. Kuzindikira/kukulitsa
– Photodiode: mphamvu yamagetsi yaying'ono, nthawi zambiri imafuna kukulitsa
– Phototransistor: mphamvu yayikulu chifukwa cha kuchuluka kwa transistor
3. Kulumikizana
- Photodiode: nthawi zambiri zimakhala zolunjika
– Phototransistor: ikhoza kukhala yopanda mzere, yodzaza mosavuta
4. Mndandanda
– Photodiode: nthawi zambiri imafuna dera lokulitsa mphamvu zamagetsi
– Phototransistor: ingagwiritsidwe ntchito mwachindunji ndi choletsa chosavuta chonyamula katundu
5. Kugwiritsa ntchito
– Photodiodes: kulumikizana kwa fiber optic, masensa olondola, muyeso wowunikira bwino
- Ma Phototransistors: zozindikira zinthu, masensa amzere, ma optocouplers, ma switch a magetsi
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5. Zitsanzo za Kugwiritsa Ntchito M'moyo Weniweni
1. Cholumikizira cha Opto
Ma optocouplers ambiri amagwiritsa ntchito ma phototransistors chifukwa chizindikiro chotulutsa chimayenera kukhala chachikulu mokwanira kuyendetsa ma digito kapena ma switching circuits.
2. Cholandirira cha infrared
Mu ma IR receiver (remotes), ma photodiode kapena ma IR receiver modules okhala ndi photodiode okhala ndi ma amplifiers amkati nthawi zambiri amagwiritsidwa ntchito chifukwa amafunika kuyankha mwachangu ku modulation (monga 38 kHz).
3. Chojambulira mzere pa loboti
Ma Phototransistors nthawi zambiri amagwiritsidwa ntchito ndi ma LED a IR ngati zotumizira kuti ziwerenge kuwala kuchokera pamalo akuda/oyera.
4. Chiyeso cha mphamvu ya kuwala
Ma Photodiode ndi oyenera kwambiri pa zipangizo zomwe zimafuna kulondola kwamphamvu komanso kulumikizana.
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6. Kesimpulan
Ma Photodiode ndi ma phototransistors onse amasintha kuwala kukhala zizindikiro zamagetsi, koma amagwira ntchito pogwiritsa ntchito njira zosiyanasiyana. Ma Photodiode amagwiritsa ntchito mapangidwe a ma electron-hole pa PN junction kuti apange photocurrent yachangu komanso yolunjika, zomwe zimapangitsa kuti ikhale yoyenera kugwiritsidwa ntchito mwachangu komanso kuyeza molondola. Koma ma Phototransistors amagwiritsa ntchito zotsatira za kuwala kuti "alowe m'malo" mphamvu yamagetsi yapansi kenako n'kuikulitsa kudzera mu transistor, zomwe zimapangitsa kuti ikhale yosavuta kugwiritsa ntchito m'ma circuits osavuta, ngakhale kuti nthawi zambiri imakhala yocheperako komanso yocheperako.
Mwa kumvetsetsa momwe zonsezi zimagwirira ntchito, tingasankhe zigawo zoyenera zosowa zathu: kaya tikufuna liwiro ndi kulondola (photodiode) kapena kukhudzidwa ndi kuphweka (phototransistors). Zikagwiritsidwa ntchito moyenera, zonsezi ndi maziko ofunikira a makina amakono a sensor optical.
