AM Mini-LED Backlight Driving Circuit Using PWM Method With Power-Saving Mechanism

This paper proposes a mini-light-emitting diode (mini-LED) driving circuit that is driven by pulse width modulation (PWM) for the backlights of active-matrix (AM) liquid crystal displays (LCDs). The proposed circuit compensates for threshold voltage (V TH ) variations of low-temperature poly-crystal...

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Bibliographic Details
Published in:IEEE journal of the Electron Devices Society 2022, Vol.10, p.256-262
Main Authors: Lin, Chih-Lung, Chen, Yi-Chien, Chang, Jui-Hung, Lin, Yu-Sheng, Chen, Sung-Chun, Lee, Ming-Hsien, Chang, Chun-Yen
Format: Article
Language:English
Subjects:
Backlights
Circuits
LCDs
Light emitting diodes
Liquid crystal display (LCD)
Liquid crystal displays
Low temperature
low-temperature poly-crystalline silicon (LTPS)
Luminous efficacy
minilight-emitting diode (mini-LED)
Power consumption
Power demand
Pulse duration modulation
Pulse width modulation
pulse width modulation (PWM)
Semiconductor devices
Silicon films
Switches
Thin film transistors
Threshold voltage
threshold voltage (VTH)
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Summary:This paper proposes a mini-light-emitting diode (mini-LED) driving circuit that is driven by pulse width modulation (PWM) for the backlights of active-matrix (AM) liquid crystal displays (LCDs). The proposed circuit compensates for threshold voltage (V TH ) variations of low-temperature poly-crystalline silicon thin-film transistors (LTPS TFTs) and the current-resistance (I-R) rise in VSS lines to supply a stable driving current. Operating the mini-LED at the high luminous efficacy by the PWM driving method and setting only the driving TFT on the path of the driving current reduce the power consumption of the backlight. Based on a 2.89-inch LCD panel with an AMLED 48\times48 backlit module, the TFTs are fabricated, measured, and fitted. Simulation results show that the relative current error rates are all below 4.67% when the V TH of the driving TFT varies by ±0.3 V and the VSS rises by 0.5 V. The voltage across VDD and VSS of the proposed circuit is 4.5 V lower than that of the 6T1C compensating driving circuit, so the power consumption of the circuit is at least 27.05% lower. Therefore, the proposed driving circuit is well suitable to use in mini-LED backlit LCDs.
ISSN:2168-6734
2168-6734
DOI:10.1109/JEDS.2022.3157935