• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.292-300
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• 2009

This paper presents an LED BLU driving circuit with a local-dimming structure. The efficiency of the proposed LED driver has been improved by parallel driving 8 serial-connected LED arrays. It employed the soft-switching boost converter topology to reduce the switching power loss of the hard switching boost converter. Soft- and hard-switching converters have the same structure except that the free-wheeling diode in the hard-switching converter is replaced with the n-channel MOSFET in the soft-switching one. The proposed boost converter was compared with the hard switching converter. The soft-switching converter reveals superior ripple and efficiency. A smaller inductance can be used for the soft-switching converter contrasting to the hard-switching one. We also studied on an over-voltage protection circuit of the output of the driver at the no load condition. The protection circuit was applied to the proposed driver, and its operation was confirmed by experiment. Using a local-dimming technique, power consumption of LCD BLUs can be reduced as low as possible according to the brightness of its image.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.3
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• pp.80-85
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• 2010

In this paper, we present an algorithm for efficient control of backlight LED in order to reduce the power consumption of LCD TV. In addition, a pragmatic implementation method is presented. In conventional local dimming control, backlight LEDs of LCD TV are divided into $M{\times}N$ blocks. And, the proper luminance for each block is computed according to input image and used for dimming control. But, LED light of each block is diffused and affects the neighboring blocks, so that luminance of each block becomes larger than that of intent. In the proposed algorithm, dimming control values are reduced by the amount of quantity affected by the neighboring blocks using light spread function, resulting in additional reduction of power consumption.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.148-150
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• 2009

We have developed 15 inch, 130 blocks local dimming FEL using printed CNT emitters, in which multiple FE blocks were built with a common gate electrode. Cathode electrode formed by the double-metal technique, in which an insulator is interposed between the addressing bus and cathode electrode.

• Information Display
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• v.16 no.3
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• pp.19-27
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• 2015

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.63-64
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• 2011

조명용 전기 에너지의 효율적인 이용을 위해서는 사용 환경에 따라 조명 기구를 부분 조광(local dimming) 제어할 필요가 있다. 본 연구에서는 LED 면광원의 부분 디지털조광 시스템을 개발하고 부분 조광된 면광원의 발광영역 및 밝기와 조명 대상물의 조도 분포와의 관계를 측정하고 평가하였다. LED 면광원을 16개의 구역으로 나누고 FPGA와 FET 스위치를 이용하여 각 구역의 점등 및 광량을 디지털 제어하였다. 또한 실험용 암실을 만들어 암실 바닥면을 91등분하고 각 지점의 조도를 측정하여 부분 조광제어에 따른 조도 분포를 평가하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.277-280
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• 2007

Field emission-back light unit (FE-BLU) was fabricated using carbon nanotube (CNT) emitter. Local dimming and local brightening techniques were achieved, which results in very high contrast ratio. In addition, the motion blur phenomenon, one of the serious problems of liquid crystal display (LCD) with cold cathode fluorescent lamp (CCFL)-BLU, was removed from LCD-TV by using FE-BLU.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.347-348
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• 2008

언급한 바와 같이 사이즈별로 시장의 규모, 특징, 개발의 방향이 약간씩 달리하고 있으나 분명한 것은 공정단순화 및 광효율향상 포함한 원가절감을 위하여 기능성 시트들을 개발을 위한 활동이 활발하게 진행하고 있다. 광원은 중형이상의 경우 CCFL, EEFL이 주류를 이루고 있으나 초대형화, 고색재현, Local Dimming을 위한 LED 광원을 채택한 LED-BLU 개발을 활발히 진행 중이다.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.86-87
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• 2009

LED backlight for LCD TV is a great alternative to CCFL backlight due to its low power consumption and flexible arrangement. Various LED backlight configurations are being used to control the backlight locally in order to achieve both power efficiency and high contrast. However, the relatively small spatial resolution of the backlight system results in showing artifacts of backlight control that is acknowledgeable to human vision. Moreover, such artifacts get worse between temporal frames. In this paper we present a method of decreasing such temporal artifacts with a Human Visual System(HVS) approach to minimize distortion caused by local backlight dimming.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.243-245
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• 2005

This paper presents a wired and wireless linked remote control system. Ethernet based network communication is used for long distance management and 2.4GHz RF network is adopted for the local area communication between the main network and the ballast. For the effective remote control and management including dimming using wired and wireless linked digital communication networks, control circuit of the ballast is implemented with fully digital circuit using MCU and EPLD. In this paper, the proper frame structure is proposed for the digital-remote lighting-control system and the detailed system configurations including fully digital controlled ballast for the induction lamp are described.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.428-431
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• 2010

LED 백라이트는 그 효율, 활용도 및 환경친화성으로 인해CCFL 백라이트를 대처 할 수 있는 좋은 대안이다. 현재 다양한 LED 백라이트 구성방식이 사용되고 있으며, 전력 절감과 명암대비 향상을 위한 다분할 제어방법(local-dimming)도 다양하게 제안되고 있다. 하지만 다분할 된 LED 백라이트의 제어 해상력은 LCD 패널의 해상력에 비해 상대적으로 매우 낮다. 이런 차이는 백라이트 제어 시 사람에게 인지되는 심각한 왜곡을 발생 시키며, 왜곡을 보상하여 극복하기 위해서는 많은 고려사항들을 파악해야 한다. 본 연구는 백라이트의 정확한 제어를 위해 주변 밝기를 고려하는 Cooperative Dimming방법을 제안하고 있으며, 본 제안 기술을 이용하여 요구 밝기를 최대한 만족하는 정확한 제어를 하며, 동시에 전력 소비를 최소화 하는 제어방법을 제안한다.