• Proceedings of the Optical Society of Korea Conference
• /
• 2007.07a
• /
• pp.321-322
• /
• 2007

• Proceedings of the KWS Conference
• /
• 2007.11a
• /
• pp.238-240
• /
• 2007

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.940-943
• /
• 2007

The objective of the research presented in this paper is to design a highly efficient LCD-TV backlight unit (BLU) which minimizes lamp count without light leakage from the BLU. A new optical plate helps to successfully distribute spatial luminance in a 46inch LCD-BLU consisting of only 20 CCFLs.

• KIPE Magazine
• /
• v.10 no.3
• /
• pp.28-35
• /
• 2005

• Transactions of Materials Processing
• /
• v.14 no.3 s.75
• /
• pp.282-290
• /
• 2005

Nowadays, TFT-LCD is widely used as display unit of many digital devices. And, the backlight unit(BLU) is used as a light source of TFT-LCD module. In the backlight unit, the most important component is a light guide, which guides the input light to the TFT-LCD module uniformly. Recently, many researchers have focused on improving the efficiency of BLU by changing the design and structure of a light guide. In the present paper, a series of simulation was performed to find the optimal luminance distribution of emanated light from the given geometry as the first step. From the results of simulations for the light guide with given V-groove pattern, the emanated light from it is mostly affected by the groove angle. In the case of acute angle, about 74 degrees was found as optimal angle to satisfy the restrictions of angular luminance distribution, FWHM, the maximum luminance, etc. However, as far as the average luminance value was concerned, the case of 120 degrees(abtuse angle) was found to be the best while prism films were added to the BLU. As a next step the light guide samples of 74 and 120 degrees were manufactured by DSF method, which was recently proposed by the authors. Of course, most of design parameters were chosen by the aid of simulation results. Finally, the results of average luminance values were compared between the simulation and DSF molded samples.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.1
• /
• pp.23-30
• /
• 2009

A new high performance and low cost unified power system is proposed through investigating conventional Power-Integrated Drive(PID) system and Power-Separated Drive(PSD) system applied to LCD TV. Since the proposed system consists of two stage, namely power and inverter stage it features high efficiency and cost effectiveness. To satisfy the safety standard of the High voltage transformer, 1:1 transformer is employed between inverter and high voltage transformer. Moreover, to ensure the Zero Voltage Switching(ZVS) of all power switches and the Pulse Count Modulation(PCM) method is employed, which controls the number of pulse at the fixed frequency and fixed duty cycle. Therefore, it features high efficiency, improved heat generation, cost effectiveness and good EMI performance including no additional current balancing coil. To confirm the validity of proposed system, comparison of conventional system, verification of experimental results are presented.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.7
• /
• pp.1275-1281
• /
• 2007

The discharge phenomena in a flat fluorescent lamp for the backlight unit of liquid crystal displays are simulated by sung a two-dimensional fluid model. The numerical methods for the calculation of plasma dynamics and the radiation transport are introduced for the discharge simulation and for the transmission of the vacuum ultraviolet lights. The simulation results are presented to compare the luminance and the luminance efficacy with the variation of gas pressure, gas mixture ratio, driving voltage, and frequency.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1086-1089
• /
• 2006

We have developed 2.4" QVGA wide color gamut LCD module using RGB-LED backlight. The color gamut is achieved 100% of NTSC compared to 70% of NTSC when used with White-LED backlight. But RGB LED backlight is difficult to maintain its color balance since RGB LED is gradually degraded by the change of ambient temperature and a long term aging characteristic, etc. This paper describes a feasibility study of our optical feedback system developed for preventing such a color shift.

• Journal of the Optical Society of Korea
• /
• v.13 no.2
• /
• pp.256-260
• /
• 2009

The optical performance of the reflective polarizer was investigated over three kinds of direct-lit backlights and/or different configurations of the optical sheets. The optical gain factor achieved by using the reflective polarizer increased as the diffuse nature of the optical sheet was enhanced, because of the more efficient polarization conversion. In addition, the gain factor decreased substantially in flat-lamp backlights compared to tubular-lamp backlights, which was ascribed to the high loss factor during the polarization recycling process due to the complex structure and large area of flat lamps. All these results suggested that reducing the loss factor of the backlight is very important for efficient polarization conversion and thus high optical gain of the reflective polarizer.

• Proceedings of the KIEE Conference
• /
• 2002.07d
• /
• pp.2568-2571
• /
• 2002

A LCD backlight inverter control IC based on the piezoelectric transformer (PZT) for Cold Cathode Fluorescent Lamp (CCFL) lighting is proposed. It is indeed a variable frequency, variable duty (VFVD) controller having dual feedback control loops for achieving both the regulation of lamp current and the maximum efficiency. The PWM controller regulates the lamp current, while the PLL controller tunes the operating frequency to the frequency that the efficiency of the combined LC-PZT resonator becomes maximum. The mixed PLL/PWM control technique lets the backlight inverter operate at the maximum efficiency in spite of the variation of component and environment. The controller features include a protection for an open or broken lamps, and an open lamp regulation.