• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.166-169
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• 2007

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive TN-LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by counting between on time and off time for video signal input during 1 frame (16.7 ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by CCFL blinking drive and TN-LCD overdriving. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

• Proceedings of the KIEE Conference
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• summer
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• pp.1281-1284
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• 2004

본 논문에서는 백라이트로 사용되는 CCFL의 점등을 위한 인버터를 연구대상으로 하였다. CCFL의 고전압 점등을 위해 다층 longitudinal 모드구조의 압전세라믹을 이용하였다. CCFL의 점등은 공진특성을 이용하는 것이므로 기계적인 공진주파수와 스위칭 주파수가 거의 일치할 수 있도록 L-C공진회로를 설계하였다. 인버터의 토플로지는 플라이백 기법을 적용하였으며 이를 위해서 권선의 배치에 의해 손실을 고려한 고주파 트랜스포머를 설계하였다. 시뮬레이션 및 실험 결과를 통하여 이에 대한 타당성을 입증하였다. 이로부터 공진주파수 48[kHz], 점등전압 600[V] 및 점등전류 6[mA] 얻었으며, 적용된 CCFL 램프사양은 관직경 $2.2{\phi}$와 관길이 314[mm], 압전세라믹 $43{\times}5.5{\times}2.3[mm]$를 이용하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.34-34
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• 2007

최근, LCD-TV의 대형화가 경쟁적으로 진행되고 있으며 대형 BLU를 제작하기 위해서는 백라이트의 직경을 대구경 화하고, 또한 고화질을 이루기 위하여 휘도특성을 개선시켜야 한다. 통상적으로 백라이트에 사용되는 고압방전은 환경이 증가할수록 휘도가 저하하는 특성을 나타내므로 대화면 LCD-TV를 개발하는데 문제점을 갖고 있다. 또한, LCD-TV 백라이트로 가장 많이 사용하는 CCFL은 병렬로 구동할 수 없어 다수의 트랜스포머가 필요하여 전체적인 BLU가격을 상승시키는 요인이 되고 있어 병렬구동이 가능한 EEFL을 백라이트로 사용하고자 하는 노력이 진행되고 있으나 CCFL에 비하여 휘도가 낮아 사용이 제한되고 있는 상황이다. 본 연구에서는 고휘도의 병력구동이 가능한 새로운 EEFL을 개발하였으며, 그 특성을 분석한 결과 기존 EEFL에 비하여 40%이상의 광효율을 증가시키고, 대구경에서 CCFL보다 2배 기존의 EEFL에 비하여 3배 이상의 휘도를 증가시킬 수 있으며, 동시에 병렬구동이 가능한 고휘도 외부전극램프를 개발하였다.

• Nuclear Engineering and Technology
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• v.34 no.4
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• pp.396-405
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• 2002

An experimental study on counter-current flow limitation phenomena in narrow annular passages was carried out The gap sizes tested were 1, 2 and 3 mm. This is very small compared with the outer diameter of the annular passage, 500 mm. It was visually observed that a CCFL might occur in some part of the periphery while the other part is remained in a counter current flow pattern. That is, non-uniform behaviour of fluids due 4o a 2-dimensional effect appear in a large diameter facility. Because of this non-uniformity, a CCFL is defined in the present work as the situation where net water accumulation is sustained. That is, some amount of water should not be allowed to penetrate the gap and accumulate over the gap at CCFL criterion. The measured data are presented in the form of Wallis＇type correlation with characteristic length of gap size. It was found that the present correlation is in good agreement with other empirical correlation based on measurements whose test section diameter is close and the gap size is much larger than that of the present test section.

• Fire Science and Engineering
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• v.33 no.6
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• pp.181-185
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• 2019

In this study, Exit light installed in offices, malls, hospitals, and factories were analyzed to analyze the luminance performance of CCFL and LED light sources. In addition, fire protection products with electrical characteristics such as Exit light may change their performance due to ambient temperature, humidity, and dust. So it was extracted by installation place and analyzed its characteristics. As a result of the experiment, Exit light for CCFL type showed the value of 'ratio of luminance 2' for large, medium and small. Considering that the reference value was 'lower than 9', the value was very good and it can be seen that there is almost no change in ratio of luminance due to aging. The Exit light for LED type showed a value of 'ratio of luminance 5', which means that the light on the display surface is not uniform. In addition, there was almost no change in ratio of luminance due to ageing, but the ratio of luminance was larger than Exit light for LED type. This is an unsatisfactory result from a visual point of view. To improve this, it is necessary to disperse the light of LED light source and strengthen the regulation on ratio of luminance.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.787-790
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• 2004

The large size and high brightness backlight system for LCD panel inspection equipment was designed, fabricated, and evaluated. The cold cathode fluorescent lamp (CCFL) instead of the hot cathode fluorescent lamp (HCFL) were used as the light source. The inverters for driving multi-lamp CCFL backlight systems were also designed and fabricated. The measured luminance of the fabricated CCFL backlight system was 20,000 cd/$m^2$ and the uniformity of the backlight was 85%. The fabricated backlight system was successfully applied to the LCD panel inspection equipment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.8-17
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• 2012

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 brightness 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.694-697
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• 2003

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by adjusting between on time and off time for video signal input during 1 frame (16.7ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by blinking drive. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.169-172
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• 2004

최근 LCD 노트북 제품의 고유한 특정인 경박단소가 요구되면서, 백라이트의 박형화로 인해 광원으로써 램프의 세경화에 대한 개발도 진행되고 있다. 특히, 노트북용 램프의 경우 발열이 심해 도광판을 비롯한 시트류의 주름현상이 발생하며, 수명연장을 위해서 전극의 표면적이 넓거나 일함수(work functuon)가 작은 재질의 개발이 필요하다. 따라서 노트북용으로 저발열, 장수명을 위한 램프를 개발하고 있으며, 본 연구에서도 기존 Ni 전극을 사용한 램프 대비 Nb, Mo, Ta 전극을 사용했을때 통일한 구동조건에서 103%의 휘도특성 개선을 확인할 수 있었고 수명면에서도 기존 Ni 전극 대비 일함수가 낮은 Nb, Mo, Ta 전극을 사용한 램프의 경우 시간경과에 따른 휘도저하가 낮은 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.475-479
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• 1995

During the hypothetical loss of coolant accident in the nuclear power plant the emergency core cooling water could not penetrate to the reactor core when the steam flow rate from the reactor core exceeds CCFL (Countercurrent flow limitation). The CCFL generated by earlier investigators are developed under the steady gas flow. However the flow instability in the reactor loop could generate oscillatory steam flow, hence their applicability under oscillating flow should be investigated. In this work, an experimental investigation of countercurrent flow in the vertical flow channel has been conducted under oscillatory gas flow. Pulsation of gas under oscillatory flow disturbs the flow pattern significantly and prevents flooding (CCFL) when its minimum value is less than the threshold gas flow rate value.