Hyeon-Yong Jang

Single-Stage Soft-Switching Converter With Boost Type of Active Clamp for Wide Input Voltage Ranges

A single-stage soft-switching converter is proposed for universal line voltage applications. A boost type of active-clamp circuit is used to achieve zero-voltage switching operation of the power switches. A simple DC-link voltage feedback scheme is applied to the proposed converter. A resonant voltage-doubler rectifier helps the output diodes to achieve zero-current switching operation. The reverse-recovery losses of the output diodes can be eliminated without any additional components. The DC-link capacitor voltage can be reduced, providing reduced voltage stresses of switching devices. Furthermore, power conversion efficiency can be improved by the soft-switching operation of switching devices. The performance of the proposed converter is evaluated on a 160-W (50 V/3.2 A) experimental prototype. The proposed converter complies with International Electrotechnical Commission (IEC) 1000-3-2 Class-D requirements for the light-emitting diode power supply of large-sized liquid crystal displays, maintaining the DC-link capacitor voltage within 400 V under the universal line voltage (90-265 Vrms).

38.4L: Late‐News Paper: A New Vertical Alignment Mode for TFT‐LCDs

A simple and cost-effective vertical alignment mode, named Smart Viewing Angle(SVA) mode, for active-matrix (AM) LCDs was developed where all the domain dividers are fabricated only on the TFT substrate side. The crucial component is the director control electrode (DCE) under the openings of the pixel electrode. The DCE maintains higher voltage than that of the pixel electrode via additional TFTs, which distorts the electric field in such a way that stable domain division is accomplished. Compared to the conventional VA modes where the additional process is required, SVA mode can achieve the wide viewing angle without any additional processes.