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LCD 백라이트를 위한 LED 드라이브 시스템의 고성능 제어
고재섭(Jae-Sub Ko),정동화(Dong-Hwa Chung) 한국조명·전기설비학회 2012 조명·전기설비학회논문지 Vol.26 No.9
This paper proposes high performance control of light emitting diode(LED) drive system for liquid crystal display(LCD) backlight. The CCFL(cold cathode fluorescent lamp)was used to a conventional LCD backlight. Due to improvement on luminous efficiency, long life and wide color gamut, LED has gradually substituted for CCFL as backlight. The backlight using LED is necessary to use many LED. For that reason, the LED backlight is using a lot of LED driving circuits. The many LED driving circuit is generated a current deviation between LED. Eventually, it is caused brightness deviation between LED. Therefore, this paper improves the current deviation using transformer and balancing capacitor to solve this problem. Also, for accurate and uniform brightnesss control, this paper is applied the artificial intelligent control to a dimming control. This paper is compared with conventional system, and validity of this paper proves through that result.
LED 백라이트 시스템을 이용한 빛 감지형 액자의 연구
조병권 ( Byung Gwon Cho ) 한국화상학회 2011 한국화상학회지 Vol.17 No.3
A lighted frame using LED backlight system operated by sensing of light was developed including in CDS sensor for sensing brightness. The LED backlight was turned off when the surrounding illumination was bright, and turned on when the surround illumination was dark. A frame was designed that the inside space was sufficient for inserting the LED backlight system and the edge of the frame could hide unnecessary light by a LED backlight. A LED backlight system was designed that a high speed switching transistor operated on and off state by connecting a CDS light sensor to base terminal because a CDS light sensor has a characteristics that a resistance was 0 in the case of bright condition and infinite value in the dark condition. 3 anodes among 9 LEDs with the series and parallel connections was joined to power supply and 3 cathodes was joined to a collector of the transistor. LEDs were light because 3 cathodes were grounded when a transistor turns on and LEDs were dark because 3 cathodes were floating in the off state. It was founded that LED backlight did not operate by the sensor under the bright illumination condition and normally operated when the surrounding illumination was dark.
LCD 모듈 검사장비용 LED 백라이트 드라이브 시스템을 위한 고효율 반브리지 직류-직류 전력변환기
유두희(Doo-Hee Yoo),정강률(Gang-Youl Jeong) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.6
This paper presents a high efficiency half-bridge DC-DC converter for an LED backlight drive system of LCD module inspection equipment. The proposed converter improves the converter efficiency using characteristics of the asymmetrical half-bridge converter and the self-driven synchronous rectifier, and thus improves the total efficiency of the LED backlight drive system. The synchronous rectifier applied to the proposed converter is the new topological synchronous rectifier, which changes slightly the transformer structure and the synchronous switch connection in the asymmetrical half-bridge converter with a conventional self-driven synchronous rectifier. Since the proposed converter utilizes the transformer leakage inductor as its resonant inductor, its structure is simplified. The proposed converter well operates under the universal DC input voltage (250~380V). The operational principle and a design example for a 100W prototype are discussed in detail, respectively. Experimental results are shown for the designed prototype converter under universal DC input voltage.