• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1657-1658
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• 2006

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter. To solve these problems of CCFL, EEFL (External Electrode Fluorescent Lamp) is introduced. Because electrode of EEFL is on the outer surface of discharge tube, the electrode is perfectly prevented from the sputtering by accelerated ions. And it is possible to drive the many CCFLs at the same time, because EEFL shows the positively resistant characteristic. But EEFL has the large non-radiative power loss in sheath. In this study the novel electrode structure was introduced in order to reduce non-radiative power loss in sheath of EEFL. The novel electrode structure comes from the idea to combine conceptually capacitive discharge with inductive discharge. Thus, this study verifies the change in the optical characteristics according to the change in electrode structure through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL electrode structure and brightness by measuring the optical characteristics.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.241-245
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• 2006

EEFL(External Electrode Fluorescent Lamp) for LCD displays are analyzed on electrical and optical characteristics by various electrode length. The electrodes of EEFL are coated at the outside of the glass tube. Brightness and efficiency of the EEFL are affected on lamp impedance characteristic. So, the experimental models are proposed for analysis and measurements of the brightness and efficiency of the lamps according to the electrode length. The sample of LCD backlight unit is used for these experiments, EEFL arrayed BLU of 32' for commercial TV display. The parameters of the experiments were quantised for simple result reading as the length of electrodes as 15, 23 and 30 mm. The inverter was designed and manufactured in the laboratory as the Full-Bridge switching inverter. The feature of the output were measured on voltages about 1000 - 1400V at the currents of 11 - 29 mA and the brightness $15,000\;cd/m^2-40,000\;cd/m^2$. The experiments have shown that the brightness are increased by increasing of the electrode lengths which have the lamp currents increased. But at an certain conditions, the brightness and efficiency were decreased because of unmatched between the inverter output and lamp impedance. The optimum applications of the EEFL BLU of 32' in this experiments have been shown to choose the parameters for driving frequencies of 100 kHz - 150 kHz, the brightness of $18,000-19,000\;cd/m^2$ and efficiencies of 40 - 45 lm/w.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.576-580
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• 2006

Mercury-free lamp, external electrode fluorescent lamp (EEFL) which includes the xenon gas, is now going on the research for the replacement of mercury lamp. The densities of excited xenon atom in the $1s_4$ resonance state and the $1s_5$ metastable state are investigated in the EEFL by a laser absorption spectroscopy under various gas pressures. We have measured the absorption signals for both $1s_4$ resonance and the $1s_5$ metastable state in the EEFL by varying the discharge currents for a given pressure. This basic absorption characteristic is very important for improvement of the VUV luminous efficiency of the EEFL as well as plasma display panel.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.223-225
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• 2005

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, an EEFL presented the possibility of using it as a light source for backlights. However, because an EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verifies the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL frequency and brightness by measuring the optical characteristics. In addition, the characteristics of the transformation of energy orbits were verified by investigating the characteristics of the wavelength according to the change in frequency through the OES.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.428-428
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• 2007

In this study, It was studied about the luminance characteristics of 17inch direct-type back light using EEFL(External Electrode Fluorescent Lamp). EEFI has a long life time because the electrode is installed outside of lamp. And it is produced low price than conventional CCFL. It does not need process of installing internal electrode. But EEFL technology has several problems such as difficulty of design driving inverter, and prevents leckage current along the skin of lamps. Therefore, by the optimizing of inverter properties, 7525 nit center luminance was acquired in almost same power consumption condition. It was almost same luminance in CCFL backlight unit. And it was operated stably in low operating temperature such as the value of $40^{\circ}C$, so that it was adopted in conventional LCD-TV application.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.703-706
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• 2009

The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1374-1377
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• 2006

The voltage distribution of an external electrode fluorescent lamp(EEFL) having a gas pressure of 50 torr and a gas composition of Ne:Ar with a ratio of 90:10 has been estimated by varying the distance between the two external electrodes and monitoring the change of the lamp voltage. The estimated voltage gradient, which represents the electric field in the positive column of the EEFL, was very sensitive to the electrode area of EEFL and was in the range of $13\;{\sim}\;27\;V/cm$ at the electrode length of $15\;{\sim}\;31\;mm$. Changing the lamp current in the range $3\;{\sim}\;5\;mA$ did not make noticeable difference in the electric field of the positive column. Theses results may serve as basic data for the optimization of electric and optic characteristics of EEFL.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.38-45
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• 2009

Recently, LCD Backlight Unit is being replaced from cold cathode fluorescent lamp(CCFL) to external electrode fluorescent lamp(EEFL) because the EEFL has high energy efficiency and long life. Also, it can reduce energy consumption and weight. So far, external electrode ring for EEFL is produced by sheet metal press forming process. Therefore it had low precision and much material loss. To solve these problems, Multi-Forming process that has five step forming process was invented. However, low productivity is another barrier. Product speed that is controlled by the rotational speed cannot be increased due to the unsatisfied design specification. The reason is that the gap between rolled two edge parts of the sheet plate is tightly inspected. Regarding this factor, the understanding of forming behavior to each process is inevitable. This paper describes the CAE analysis of the multi-forming process by PAM-STAMP.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1066-1069
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• 2003

요즘, LCD TV 가 등장하면서 LCD 백라이트로써 LCD TV 에 적용하기 위해서는 무엇보다도 휘도특성의 개선이 요구되고 있다. TV 대응 LCD Panel 은 Monitor 대응 제품에 비해서 일반적으로 해상도가 낮으므로, 투과율면에서 장점은 있으나, 현재의 백라이트 구조로는 만족할만한 성능을 낼 수 없는 상황이다. 그러므로 고휘도 백라이트를 위해서 EEFL(External Electrode Fluorescent Lamp) 혹은 CCFL(Cold Cathode Fluorescent Lamp) 의 복수 사용을 전제로 한 직하방식에 대한 개발 검토가 활발히 이루어지고 있다. 직하방식에 의한 고휘도화는 램프수는 증가되지만 프리즘시트를 사용하지 않아서 가격 경쟁력이 있다. 따라서 본 연구에서는 EEFL 16등을 이용하여 17인치 직하형 백라이트를 제작하여 기구적, 전기적, 광학적 특성을 분석하였으며, 그 결과 11,700 nit 의 휘도를 달성하여 TV 대응 수준을 확보하였다.