AM PWM Driving Circuit for Mini-LED Backlight in Liquid Crystal Displays

This work proposes a mini-LED driving circuit that adopts the pulse-width modulation (PWM) driving method for use in a liquid-crystal display (LCD) backlight. The proposed circuit can compensate for the threshold voltage ( \text{V}_{\mathrm{ TH}} ) variation in a low-temperature poly-crystalline sil...

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Bibliographic Details
Published in:IEEE journal of the Electron Devices Society 2021, Vol.9, p.365-372
Main Authors: Lin, Chih-Lung, Chen, Sung-Chun, Deng, Ming-Yang, Ho, Yuan-Hao, Lin, Chieh-An, Tsai, Chia-Ling, Liao, Wei-Sheng, Liu, Chih-I, Wu, Chia-En, Peng, Jia-Tian
Format: Article
Language:English
Subjects:
Active matrix liquid crystal displays
Active-matrix display
Backlights
Circuits
Current pulses
high dynamic range
LCD backlight
Light emitting diodes
Liquid crystal displays
Low temperature
mini-LED
Power consumption
Power demand
Pulse amplitude modulation
Pulse duration modulation
Pulse width modulation
Semiconductor devices
Silicon films
Thin film transistors
thin-film transistor
Threshold voltage
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Summary:This work proposes a mini-LED driving circuit that adopts the pulse-width modulation (PWM) driving method for use in a liquid-crystal display (LCD) backlight. The proposed circuit can compensate for the threshold voltage ( \text{V}_{\mathrm{ TH}} ) variation in a low-temperature poly-crystalline silicon thin-film transistor (LTPS TFT) and a VSS current-resistance (I-R) rise, to generate a stable driving current to power the mini-LED. Since the proposed circuit uses the PWM method, the mini-LED can be operated at the best luminance-efficacy point, minimizing the power consumption of the circuit. The electrical characteristic of fabricated LTPS TFTs are measured to establish a simulation model to demonstrate the feasibility of the proposed circuit. Simulation results demonstrate that the relative mini-LED current error rates are below 9% when the \text{V}_{\mathrm{ TH}} varies ± 0.3 V and VSS rises by 1 V. With respect to precise control of the gray level, the time shifts of current pulses are within 11.48 us over the whole grayscale. The improvement in the power consumption of the proposed circuit is more than 21% than that of a circuit that is driven by pulse amplitude modulation.
ISSN:2168-6734
2168-6734
DOI:10.1109/JEDS.2021.3065905