Tsarin Kewayawa AM PWM don Haske na Baya na Mini-LED a cikin LCDs: Bincike da Fahimta

1. Gabatarwa & Bayyani

Wannan takarda ta gabatar da ci gaba mai mahimmanci a fasahar haske na baya don Allon Nuna Ruwa mai Kankara (LCDs). Tana magance wata matsala mai mahimmanci wajen cimma Ingantaccen Kewayon Haske (HDR) tare da haske na baya na mini-LED: rashin daidaiton kwararar da ake kaiwa saboda bambance-bambancen da ke tattare da kera Transistor na Bakin ciki na Siliki mai yawan barbashi a ƙananan zafin jiki (LTPS TFTs) da raguwar ƙarfin lantarki a kan layukan wutar lantarki. Marubutan sun ba da shawarar sabon Tsarin Kewayawa Mai Aiki (AM) wanda ke amfani da Tsarin Canza Fadin bugun jini (PWM) maimakon Tsarin Canza Girman bugun jini (PAM) wanda ya fi kowa. Babban sabon abu shine ikon da'irar na ramawa don canjin ƙarfin bakin kofa ($V_{TH}$) a cikin TFT mai kaiwa da kuma bambance-bambancen wutar lantarki ($V_{SS}$), ta haka ne ake samar da kwarara mai karko don mini-LED. Wannan karko yana da mahimmanci don kawar da lahani na gani ("mura") da kuma ba da damar duhun wuri daidai. Bugu da ƙari, ta hanyar sarrafa mini-LED a mafi kyawun wurin haske ta hanyar PWM, ƙirar ta sami raguwa mai yawa a cikin amfani da wutar lantarki—fiye da 21% idan aka kwatanta da da'irorin da PAF ke kaiwa—yayin da take kiyaye ingantaccen sarrafa siffar launin toka.

2. Fasaha ta Tsakiya & Hanyoyin Aiki

2.1 Kalubale: Rashin Daidaiton TFT & Ragun Wutar Lantarki (IR Drop)

Neman haske na baya na mini-LED mai ingantaccen ƙima, mai yawan yanki don LCD HDR yana fuskantar ƙuntatawa guda biyu na kayan aiki. Na farko, tsarin Excimer Laser Annealing (ELA) da ake amfani da shi don ƙirƙirar LTPS TFTs yana haifar da rashin daidaiton iyakokin barbashi, yana haifar da bambance-bambance mai yawa a sarari a cikin ƙarfin bakin kofa na transistor ($V_{TH}$). Na biyu, juriya mai cutarwa a cikin dogayen layukan wutar lantarki da ke ciyar da jerin pixels yana haifar da raguwar ƙarfin lantarki (I-R) (ko tashi don $V_{SS}$), ma'ana pixels da suka yi nisa daga tushen wutar lantarki suna karɓar wutar lantarki daban. A cikin da'irar tushen kwarara ta al'ada wanda aka tsara ta hanyar ƙarfin lantarki (kamar 2T1C mai sauƙi), waɗannan bambance-bambancen kai tsaye suna canzawa zuwa kwararar kaiwa mara daidaituwa don mini-LEDs, suna haifar da rashin daidaiton haske da ake iya gani—wata matsala mai mutuƙa don hoton HDR wanda ke buƙatar cikakkiyar daidaito a wurare masu duhu.

2.2 Tsarin Kewayawa na AM PWM da Ake Shawarar

Da'irar da aka ba da shawarar ta yi juyi da hikima. Maimakon ƙoƙarin cikakkiyar da'irar tushen kwarara mai karko (wacce ke da matukar hankali ga $V_{TH}$ da $V_{SS}$), tana amfani da hanyar PWM ta dijital. Babban ra'ayi shine samar da bugun jini mai kaiwa wanda girmansa an yi shi da gangan ya dogara da $V_{TH}$ da $V_{SS}$, amma wanda faɗinsa aka daidaita ta hanyar juyawa, mai ramawa. Ƙirar da'irar tana tabbatar da cewa jimillar cajin da ake bayarwa a kowane firam ($Q = I \times t_{pulse}$) ya kasance mai tsayi duk da bambance-bambancen a cikin kwararar nan take (I). Ta hanyar ƙirƙira hanyoyin amsa da lokaci a cikin da'irar pixel a hankali, ana daidaita faɗin bugun jini ta atomatik don ramawa don canje-canje a cikin girman kwarara, yana tabbatar da fitar da haske mai daidaito. Wannan "gyaran dijital" yana da ƙarfi ga bambance-bambancen tsari fiye da tsare-tsaren ramawa na analog kawai.

2.3 Cikakkun Bayanai na Fasaha & Tsarin Lissafi

Ana iya ƙididdige aikin zuwa ƙa'idar daidaita caji. TFT mai kaiwa (misali, a cikin yanki mai cika) yana ba da kwarara zuwa mini-LED da capacitor mai haɗawa. An ba da wannan kwarara kamar haka: $$I_D = \frac{1}{2} \mu C_{ox} \frac{W}{L} (V_{GS} - V_{TH})^2$$ inda $V_{GS}$ ya shafi $V_{SS}$ (ragun I-R). Bambanci $\Delta V_{TH}$ ko $\Delta V_{SS}$ yana haifar da canji $\Delta I_D$. Da'irar da aka ba da shawarar ta haɗa da tsarin sa ido/kwatanci wanda ke gano ƙarfin lantarki akan capacitor mai haɗawa. Ana ƙare bugun jini lokacin da wannan ƙarfin lantarki ya kai ga tunani, ma'ana faɗin bugun jini $t_{pulse}$ ya gamsar da: $$\int_0^{t_{pulse}} I_D(t) dt = Q_{target} = akai-akai$$ Idan $I_D$ ya ragu saboda babban $V_{TH}$ ko ƙananan $V_{DD}$, $t_{pulse}$ yana ƙaruwa ta atomatik don isar da jimillar caji ɗaya $Q_{target}$, da sauran su. Wannan yana tabbatar da haske, wanda yake daidai da $Q_{target}$, ya kasance mai karko.

3. Sakamakon Gwaji & Aiki

3.1 Saitin Siminti & Samfurin

An tabbatar da yuwuwar ta hanyar siminti na SPICE ta amfani da samfurin LTPS TFT na gaskiya. An ciro sigogin samfurin daga ainihin TFTs da aka ƙera don nuna daidai rarraba $V_{TH}$ na ƙididdiga da bambance-bambancen motsi da ake tsammani daga tsarin ELA. Simintin ya gwada aikin da'irar a kusurwoyi: TFTs na al'ada, sauri (ƙananan $V_{TH}$), da jinkiri (babban $V_{TH}$), haɗe tare da matakan $V_{SS}$ na al'ada da masu canzawa.

3.2 Ma'auni Mafi Muhimmanci na Aiki

• Daidaiton Kwarara: Ana auna shi azaman kuskuren dangi a cikin kwararar mini-LED a ƙarƙashin matsanancin rikice-rikice.
• Layin Siffar Launin Toka: An kimanta shi ta hanyar canjin lokaci na bugun jini na kwarara a cikin dukkan kewayon siffar launin toka (0-255).
• Ingancin Wutar Lantarki: An ƙididdige shi ta hanyar kwatanta jimillar amfani da makamashi a kowane firam na da'irar PWM da da'irar PAM daidai wanda ke cimma haske iri ɗaya.

3.3 Sakamako & Jaridu

Jadawali 1: Kuskuren Kwarara vs. Bambancin $V_{TH}$/$V_{SS}$ – Jadawali ko jadawali layi zai nuna cewa don matsar $V_{TH}$ na ±0.3V da hawan $V_{SS}$ na 1V (siminti mai tsanani na ragun I-R), kuskuren dangi a cikin kwararar fitarwa yana ƙunshe a ƙasa da 9%. Sabanin haka, da'irar 2T1C ta al'ada za ta nuna kurakurai sama da 30-40% a ƙarƙashin yanayi iri ɗaya.

Jadawali 2: Faɗin bugun jini vs. Siffar Launin Toka – Zane mai zana ƙimar siffar launin toka da aka umarta da faɗin bugun jini da aka samar zai nuna babban layi. Ma'auni mai mahimmanci shine matsakaicin karkata daga lokacin da ya dace, wanda aka ruwaito cewa yana cikin 11.48 µs a cikin dukkan siffar launin toka, yana nuna daidaitaccen canzawa daga dijital zuwa lokaci.

Jadawali 3: Kwatancin Amfani da Wutar Lantarki – Tarihin kwatancen zai nuna a fili cewa da'irar PWM da aka ba da shawarar tana amfani da wutar lantarki fiye da 21% ƙasa da ma'aunin PAM. Wannan saboda PWM yana ba da damar LED a kai shi a mafi girman ingancin kwarara a ci gaba, yana daidaita fitar da haske tare da lokaci, yayin da PAM sau da yawa yana sarrafa LED a matakan kwarara marasa inganci don ƙananan haske.

4. Tsarin Bincike & Nazarin Lamari

Tsari: "Tsayayya vs. Rikitarwa" a cikin Ƙirar Pixel na Nuni.
Wannan takarda tana ba da cikakken nazarin lamari don wannan tsari. Za mu iya bincika da'irorin pixel na nuni tare da ginshiƙai biyu: 1) Tsayayya ga Bambance-bambancen Tsari/Aiki (misali, matsar $V_{TH}$, ragun IR), da kuma 2) Rikitarwar Da'ira (ƙididdigar transistor, buƙatun siginar sarrafawa, yankin shimfidawa).

• 2T1C Mai Sauƙi (PAM): Ƙananan rikitarwa (transistors 2), amma ƙananan tsayayya. Mai hankali ga duk bambance-bambancen, yana haifar da mura. Gama gari a farkon OLED da haske na baya mai sauƙi.
• Pixels na AMOLED Masu Tsarar Ƙarfin Lantarki Masu Rikitarwa (4T2C, 5T2C, da sauransu): Babban tsayayya. Yi amfani da amsa na ciki don ramawa $V_{TH}$ da wani lokacin $IR$ drop. Duk da haka, babban rikitarwa (ƙarin TFTs, capacitors, da layukan sarrafawa) yana rage ma'aunin buɗe ido da yawan amfanin ƙasa.
• Da'irar AM PWM da Ake Shawarar: Ta sanya kanta a cikin wuri mai daɗi. Tana cimma babban tsayayya (tana ramawa duka $V_{TH}$ da $V_{SS}$) tare da matsakaicin rikitarwa. Ƙididdigar transistor tana da yuwuwa ta fi 2T1C girma amma yuwuwar ta fi ƙasa da mafi rikitarwar pixels na AMOLED, kamar yadda ta maye gurbin samar da ƙarfin lantarki na analog daidai da sarrafa lokaci na dijital. Nazarin lamarin ya nuna cewa don aikace-aikacen da ake haɗa fitar da haske akan lokaci (kamar haske na baya na LCD ko yuwuwar nunin micro-LED), dabarun PWM da aka gyara ta dijital na iya zama hanya mafi yawan yanki da ingancin wutar lantarki zuwa daidaito fiye da ramawar analog kawai.

5. Bincike Mai Zurfi & Fahimtar Kwararru

Fahimta ta Tsakiya: Lin da sauransu sun aiwatar da juyi mai haske. Sun gane cewa cin nasara a cikin yaƙin da aka yi asarar don cikakkiyar daidaiton analog a cikin LTPS ba shi da inganci fiye da karɓar tsarin sarrafa dijital. Ainihin sabon abu ba wai kawai wata da'irar ramawa ba ne; shine yanke shawara na dabarun yin amfani da PWM a matsayin mai canzawa na farko na sarrafawa, yana sa tsarin ba shi da hankali ga rashin cikar analog da ke addabar kera nuni. Wannan yana tunawa da canjin a cikin canzawa na bayanai daga analog kawai zuwa gine-ginen da suka wuce gona da iri, masu siffar amo (kamar a cikin DACs na sauti) don kewaye da rashin daidaiton abubuwan haɗin gwiwa.

Kwararar Ma'ana: Hujja tana da inganci: 1) Haske na baya na mini-LED yana buƙatar kwarara mai karko don HDR. 2) LTPS TFTs da hanyoyin sadarwar wutar lantarki ba su da daidaituwa a asali. 3) Don haka, ramawa wajibi ne. 4) Ramawar analog da ake da ita (daga AMOLED) tana aiki amma tana da rikitarwa. 5) Maganin mu: Bari kwarara ya bambanta, amma sarrafa lokaci daidai don kiyaye jimillar caji akai-akai. 6) Sakamako: Tsayayyar daidaito + fa'idar ƙari na ceton wutar lantarki daga mafi kyawun wurin aiki na LED. Ma'ana tana da gamsarwa kuma tana da goyan baya ta hanyar siminti.

Ƙarfi & Kurakurai:
Ƙarfi: Ramawar biyu ($V_{TH}$ da IR) babban nasara ne. Ceton wutar lantarki >21% fa'ida ce ta gaske, mai shirye don kasuwa. Ra'ayin yana da kyau kuma yana iya yin girma zuwa nunin kai tsaye na micro-LED, inda daidaito ya zama ƙalubale mafi girma, kamar yadda aka lura a cikin bincike daga manyan 'yan wasa kamar PlayNitride da VueReal. Amfani da ingantaccen fasahar LTPS yana sauƙaƙa karɓar masana'antu.
Kurakurai & Tambayoyi: Takardar siminti ce kawai. Tabbatar da duniya ta zahiri tare da jeri na jiki, auna ainihin raguwar mura, shine mataki na gaba mai mahimmanci. Binciken rikitarwar da'ira (ƙididdigar transistor, tasirin yankin shimfidawa akan ƙirar kayan haske na baya) yana da haske. Ta yaya mitar canzawa na PWM ke shafar EMI? Don matsanancin mitar sabuntawa (misali, nunin wasan 240Hz), shin mafi ƙarancin faɗin bugun jini da ake buƙata don siffar launin toka mai zurfi ya zama abin iyakancewa? Matsar 11.48 µs, ko da yake ƙanana, yana buƙatar mahallin—wane kashi na lokacin firam ne wannan a mitocin sabuntawa daban-daban?

Fahimta Mai Aiki: Ga masu yin allon nuni (kamar marubucin haɗin gwiwa AUO), wannan tsari ne don masu kaiwa na gaba na haske na baya. Yakamata su yi samfuri nan da nan ƙaramin jerin gwaji. Ga kamfanoni na kayan aiki da kayan aiki, wannan yana ƙarfafa ƙimar ci gaba da fasahar LTPS, yana iya tsawaita rayuwarta a kan abokan hamayya kamar TFTs na oxide don wannan aikace-aikacen. Ga masu bincike, yakamata a bincika ƙa'idar "gyaran dijital ta hanyar PWM" don nunin kai tsaye na micro-LED, yana iya sauƙaƙa buƙatun canja wuri da binning masu ban tsoro. Ya kamata masana'antu su lura idan za a iya haɗa wannan hanyar tare da dabarun sarrafa hoto na yanki na lokaci, kama da ra'ayoyin da aka bincika a cikin nunin lissafi.

6. Aikace-aikace na Gaba & Hanyoyin Ci Gaba

Tasirin wannan aikin ya wuce haske na baya na mini-LED LCD:

1. Nunin Kai Tsaye na Micro-LED: Wannan shine mafi kyawun shugabanci. Micro-LEDs suna fama da mafi girman inganci da bambance-bambancen binning na tsawon raƙuman ruwa. Da'irar mai aiki ta tushen PWM wacce ke ramawa ga rashin daidaiton TFT da bambancin asali na LED na iya rage farashi da rikitarwar tsarin canja wuri ta hanyar sassauta buƙatun binning. Bincike daga cibiyoyi kamar MIT da Stanford sun nuna ramawa a matsayin mai ba da damar kasuwanci na micro-LED.
2. Nunin Bayyane da Sassauƙa: A kan abubuwan da ake sawa sassauka, halayen TFT suna canzawa tare da matsin lanƙwasa. Hanyar gyaran dijital mai ƙarfi kamar wannan na iya kiyaye daidaiton hoto a ƙarƙashin nakasar injiniya.
3. Aikace-aikacen Nuni Masu Haske: Don nunin motoci ko jagororin raƙuman ruwa na ƙari (AR) waɗanda ke buƙatar haske mai tsananin haske, sarrafa LEDs a mafi girman inganci (kamar yadda PWM ke ba da damar) yana da mahimmanci don sarrafa zafi da kasafin wutar lantarki.
4. Nunin Haɗe-haɗe na Na'ura mai auna firikwensin: Nuni na gaba tare da na'urori na gani da aka haɗa (don yatsa, hasken yanayi, ko firikwensin lafiya) suna buƙatar haske mai tsayayye kuma mara amo. Haske na baya mai daidaito, wanda aka sarrafa ta dijital, ya dace da irin waɗannan aikace-aikace.
5. Bukatun Ci Gaba: Aikin gaba dole ne ya mai da hankali kan: a) Tabbatar da Silicon tare da manyan jerin gwaji, b) Rage yankin da'ira don haɓaka yawan yanki na haske na baya, c) Bincikin amfani da sabbin fasahohin TFT (kamar oxide na ƙarfe) a cikin wannan tsarin PWM, da kuma d) Haɓaka masu sarrafa lokaci masu ci gaba waɗanda za su iya haɗuwa cikin sauƙi tare da wannan gine-ginen PWM na matakin pixel.

7. Nassoshi

1. C.-L. Lin da sauransu, "AM PWM Driving Circuit for Mini-LED Backlight in Liquid Crystal Displays," IEEE Journal of the Electron Devices Society, vol. 9, shafi. 365-373, 2021. DOI: 10.1109/JEDS.2021.3065905.
2. H. Chen da sauransu, "Active Matrix Micro-LED Displays: Progress and Prospects," Journal of the Society for Information Display, vol. 29, lamba. 5, shafi. 339-359, 2021.
3. Z. Liu da sauransu, "Review of Recent Progress on Micro-LEDs for High-Density Displays," IEEE Transactions on Electron Devices, vol. 68, lamba. 5, shafi. 2022-2032, 2021.
4. S. R. Forrest, "The path to ubiquitous and low-cost organic electronic appliances on plastic," Nature, vol. 428, shafi. 911–918, 2004. (Aikin gama gari akan OLEDs, yana nuna ƙalubalen daidaito na farko).
5. J. G. R. da sauransu, "A Voltage-Programmed Pixel Circuit for AMOLED Displays Compensating for Threshold Voltage and Mobility Variations," IEEE Transactions on Electron Devices, vol. 58, lamba. 10, shafi. 3347-3352, 2011. (Misalin ramawar analog mai rikitarwa).
6. Kwamitin Ƙasa da Ƙasa don Metrology na Nuni (ICDM), "Information Display Measurements Standard (IDMS),." (Hukuma akan ma'auni na aikin nuni kamar daidaito da HDR).
7. PlayNitride Inc., "PixeLED® Display Technology," [Online]. Akwai: https://www.playnitride.com/. (Shugaban masana'antu a fasahar micro-LED).
8. VueReal Inc., "Micro Solid-State Printing," [Online]. Akwai: https://vuereal.com/. (Kamfani mai mai da hankali kan canja wuri da haɗin gwiwar micro-LED).