• Information Display
• /
• v.6 no.4
• /
• pp.11-21
• /
• 2005

평판 디스플레이 장치가 LCD-TV에 사용되는 경우 시야각 특성과 동화상 성능은 보다 중요한 성능이 된다. 전반적인 LCD의 화질 특성은 시야각 특성과 동화상 응답 속도를 제외한 모든 부문에서 경쟁 기술보다 우세하다. 이러한 디스플레이의 시야각 특성을 개선하기 위해 LCD업계에서는 IPS, MVA, PVA 등 시야각 특성이 개선된 광시야각 액정 Mode를 개발하여 사용하고 있지만 여전히 LCD는 자발광 디스플레이에 비하여 측면 시인성 측면으로 열세에 있었다. 최근에는 LCD의 측면 시인성을 획기적으로 개선 할 수 있는 기술이 개발되어 더 이상 LCD-TV 응용에서 문제가 되지 않을 수준이 되고 있다. 본 논문에서는 여러가지 광시야각 액정모드 LCD의 측면 시인성 향상 기술에 대한 개략적인 사항을 알아보고, 그 중 Super PVA 액정 기술의 기본원리와 동작 방법에 대하여 상세히 기술하기로 한다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.799-802
• /
• 2004

In this paper, the active backlight control technology with data processing algorithm was developed in order to improve image quality for IPS-mode LCD-TV applications. The image blinking problem caused by repeatedly abrupt change of the backlight luminance was solved by algorithms-Fba(Flexible Boundary algorithm) and Cfa(Cumulative Feedback algorithm)-and the optimized number and space of backlight dimming steps based on perception. In the IPS-mode 42" TFT-LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of lower block luminance and higher white luminance. Additionally, Power consumption and LCD temperature was decreased.

• 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.

• KIPE Magazine
• /
• v.27 no.3
• /
• pp.31-37
• /
• 2022

20세기 디스플레이의 중심에 서 있던 브라운관이 1990년대 이후 PDP나 LCD 등 박형 평판디스플레이로 대체되면서 현재까지 스크린 사이즈의 중대형화, 고해상도화, 저소비전력화, 저가격화 등 다양한 노력들이 지속적으로 이루어져 왔다. 특히 TV와 디스플레이 산업에 있어 우리나라는 2004년 이후 세계 점유율 1위의 위치를 꾸준히 유지해 오고 있으나 2020년에 들어서면서 중국과의 격차가 1%대로 좁혀지고 있는 등 TV 시장에 대한 후발주자의 공세가 점차 거세지고 있다. 이에 따라 LCD에서 OLED나 마이크로 LED 등 차세대 디스플레이로의 사업구조 전환을 서두르고 있으며 후발주자의 추격 또한 만만치 않은 상황에 있다. 이러한 가운데 코로나 19를 계기로 비대면 문화가 확산되면서 IT 제품 수요가 지속적인 강세를 보이고 있으며 TV와 디스플레이도 대형 및 프리미엄 TV를 중심으로 그 수요가 빠르게 확대 개선되고 있는 추세로서 100인치대 내외의 대화면, 8K UHD와 같은 초고해상도, 5-10mm 수준의 초슬림에 대한 요구가 절정을 이루고 있다. 이를 위해 TV와 디스플레이를 구성하는 핵심 요소인 전원장치 또한 고전력밀도와 초솔림화를 위한 많은 연구 개발이 이루어지고 있으며 특히 최근 EU의 에코디자인 규정에 따라 디스플레이의 소비전력과 효율 또한 매우 중요한 이슈로 부각되고 있다. 한편, 최근까지 주류를 이루고 있는 LCD TV와 디스플레이용 전원장치의 경우 역률 개선을 위한 PFC(Power Factor Correction) 단과 LED 백라이트 및 영상보드의 전원공급을 위한 절연형 DC/DC 단으로 구성되며, OLED와 같은 저전압 대전류 디스플레이 소자의 경우 전반적인 전원장치의 구성은 유사하나 비절연형 DC/DC컨버터가 추가적으로 요구되기도 한다. 본고에서는 상기한 바와 같은 최근 추세에 따라 TV 및 디스플레이용 전원장치의 각 구성요소별로 고효율, 고밀도, 초슬림을 위한 전원회로 기술에 대해 간략히 소개한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.05a
• /
• pp.123-127
• /
• 2004

Cold cathode fluorescent lamp (CCFL) has been used as a light source for direct type backlights for LCD monitors or TV. One inverter for one CCFL was necessary for maintaining the lamp current so that many inverters were used to drive as many CCFLs of direct type backlight for LCD TV. An inverter for driving 16 CCFLs was developed to reduce the backlight cost. The length and diameter of CCFL were 450mm and 4mm, respectively. Backlight including 16 CCFLs for 26" LCD TV was assembled by using one inverter. The uniformities of the assembled backlight operated by the conventional inverter and the newly developed inverter were 75% and 88%, respectively.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1203-1207
• /
• 2008

For a large sized, ultra definition (UD) and high refresh rate for motion blur free AMLCD TVs, amorphous IGZO thin film transistor (TFT) are applied and investigated in terms of threshold voltage ($V_{th}$) shift influenced by active layer thickness uniformity, source drain etching technology, heat treatment and passivation condition. Optimizing above parameters, we fabricated the world's largest 15 inch XGA AMLCD successfully.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.10a
• /
• pp.69-72
• /
• 2009

Recently, LED(Light Emitting Diode) TV has attracted greate attention due to its super-slim form factore as well as low power consumption. LED TV is actually an LCD(Liquid Crystal Display) TV in which edge-lit LED backlight is adopted. In the presente study, we report on the comparison of optical characteristics 55-inch edge-lit LED backlight and CCFL(Cold Cathode Fluorescent Lam)backlight. The angular distribution of the luminance and the on-axis luminance gain on each optical component were investigated and compared. The effect of the backlight structure on the performance of the optical films was studied and discussed.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.4
• /
• pp.1646-1654
• /
• 2015

In this paper, a single-switch ZVZCS quasi-resonant CLL isolated DC-DC converter for driving a low-power (less than 100 W) 32'' LED backlighting liquid crystal display television (LCD TV) is proposed. The proposed converter exhibits both forward and flyback operational characteristics. All semiconductors are activated and deactivated under the soft switching conditions during the switching transition without additional active devices. The switching frequency varies less than about 10 kHz for load variations, leading to minimizing the efficiency reduction under light load. Furthermore, the low di/dt and dv/dt by soft switching enhance the electromagnetic interference (EMI) performance above 1 MHz. A theoretical analysis is described in detail, and a 72-W prototype converter verifies the validity of the analysis.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.1
• /
• pp.52-59
• /
• 2010

The conventional CCFL (Cold Cathode Fluorescent Lamp) inverter used in the backlight unit for LCD-TV, composed of the three power stage, can degrade the whole power conversion efficiency. In this paper, a novel scheme to drive the CCFL, composed only of the two power stage without using a dc/dc power stage, is proposed to enhance the whole power conversion efficiency. By adopting the proposed "4-in-1 Transformer", the current balance and the simultaneous ignition among the four CCFL lamp are assured with the one inverter circuit. The proposed scheme features the simple circuit structure, which can save the volume and the cost in the LCD backlight unit. Design considerations are discussed and design procedures are derived. Experimental results of the proposed scheme for 40" LCD-TV are presented to confirm the theoretical analysis.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1149-1152
• /
• 2005

The frequency of inverters for driving multi-lamp backlights for LCD TV was synchronized to reduce noise from lamps and noise generated from PWM dimming.