Reducing Power Consumption of Active-Matrix Mini-LED Backlit LCDs by Driving Circuit

Abstract

An active-matrix (AM) driving circuit using a low-temperature poly-silicon thin-film transistor (LTPS TFT) is developed to reduce the power consumption of mini-light-emitting diode (LED) backlit liquid-crystal displays (LCDs). By lowering the drain-source voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> ) of the switching TFT on the driving current path, the range of required voltage across the proposed circuit can be reduced, decreasing the power consumption of the mini-LED backlight. The proposed circuit also can compensate for V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> variation in the LTPS TFT and the I- R rise of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SS</sub> to provide a uniform driving current to flow through the mini-LED. By measuring the I- V curves of a fabricated LTPS TFT, we build a reliable simulation model and compare the proposed circuit to that of the state-of-the-art. Simulated results indicate that the proposed circuit can improve the power consumption by 16.67% and reduce the current error rates below 8% when the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of TFT varies by ±0.3 V and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SS</sub> rises +1 V. Measured results further confirm that the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> of the switching TFT is reduced by 2.208 V compared to a 6T2C compensating circuit. Therefore, widespread applications of the proposed circuit for AM mini-LED backlit LCDs to produce high-dynamic-range images are foreseeable.