• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.843-848
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• 2006

This paper explains the design and fabrication of an inverter for LCD backlight using a multilayer piezoelectric transformer. That inverter is operated by the burst dimming method whose dimming signal is controlled by the duty ratio of rectangular switching signal to a PWM controller. The brightness of CCFL's are investigated according to the various dimming signals, and when those CCFL's are turned on, the temperature distributions on the piezoelectric transformer and circuit components of the inverter are also investigated by a thermo-camera.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.153-158
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• 2018

In this paper, we have studied a dimming level control method to satisfy both lighting and communication performance in visible light communication system. In the case of the most commonly used OOK and RZ-OOK modulation schemes, continuous Burst Zero Duration will seriously degrade the lighting function. This causes not only the illumination but also the performance of the entire system to deteriorate. Through this study, we analyzed the dimming level characteristics of the existing system and proposed the Illegal Pulse Insertion (IPI) algorithm as a technique to increase the dimming level. Through this, it is possible to effectively control the dimming level and improve the QoS of both lighting and communication by resolving the flicker phenomenon and dimming level reduction in the existing modulation and demodulation system.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.3 s.303
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• pp.63-70
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• 2005

The electrodeless lamps using the induction discharge have a long lifetime and a high tolerance for the variable output conditions of a ballast since they don't need the electrodes. This paper proposed two novel dimming algorithms for the Electrodeless lamps and described the resonant inverter adopted the proposed methods. The proposed dimming algorithms are based on the conventional burst dimming method which is normally adopted for LCD back-lights. One of the proposed algorithms is a improved burst dimming method, which controls the illumination by duty ratio of $5\%$ and its control circuit is formed by simple digital logics. The other algorithm is a burst PWM average duty ratio control method, which controls the illumination by duty ratio of $1\%$ and its control circuit is formed by more complex digital logics than the first method. To verify the validity of the proposed dimming methods, a prototype experimental setup for 100W Electrodeless lamps is carried out and its results are presented in this paper.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.747-750
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• 1999

A 30Watt inverter with 300: 1 dimming capability for high luminance, one cell, surface discharge plasma light source for LCD backlight was designed and tested. It was possible to achieve 300:1 dimming control by using the push-pull type inverter with burst-mode dimming control. The surface discharge plasma light cell with luminance of more than 5, 260 cd/$m^2$ was successfully operated.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.4
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• pp.201-205
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• 2004

The CCFL dimming control methods are generally used lamp current regulation or average current adjustment method feeding the CCFL inverter. Inverter operation frequency is higher than resonant frequency for safe operation. In this study, we design the half-bridge type series and parallel resonant converter circuit that switches at variable frequency modulation methods to control the output power. This method has advantages such as low EMI and reduced harmonics, and it is convenient for dimming control using a microprocessor. The validity of this study is confirmed from the simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.393-395
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• 2006

This Paper represents a dimming control characteristics of an external electrode fluorescent lamp (EEFL) inverter, which is replacing a cold cathode (luorescent lamp (CCFL) in the area of the large-sized LCD backlight. The analog and burst dimming control methods for the EEFL are compared and the control characteristics are anlayzed through the experiments.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1410-1412
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• 2005

A novel dimming algorithm for the electronic ballast of the electrodeless lamp is proposed. The proposed algorithm is based on the burst dimming method and controls the duty ratio for the two switches of the electronic ballast by pulse width modulated signal. The preposed algorithm was implemented by a fully digital circuit using EPLD device. To verify the validity of the proposed algorithm, the implemented control circuit was applied to the electronic ballast for a 100W electrodeless fluorescent lamp. As a result, the wide illumination dimming range from 5% to 100% was obtained.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.487-489
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• 2004

As the electrodes are not needed, the electrodeless lamps using the induction discharge have a long lifetime and are robust against the variable output condition of a ballast. This paper proposed a dimmable resonant inverter for the electrodeless lamps. The proposed resonant inverter formed a half bridge inverter adopted FWM to control the average output power of the inverter and the illumination of a lamp. In this paper, the proposed dimming algorithm was described and the prototype experimental setup for 100W electrodeless lamps was carried out to verify the validity of the proposed dimming method.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.504-513
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• 2009

This paper proposes the new type LED driver modularization for illumination LED driver. The proposed LED driver circuit insulates a hot GND of AC input power and a cold GND of LED driver part by using a fly-back converter. In order to control easily the current of the LED, the fly-back converter is operated in the discontinuous mode with excellent dynamic characteristics, and the characteristics of the LED are verified after the closed loop control is performed using a KIA2431. The LED driver module allows the wide AC power input ranges and realizes the burst dimming function which directly regulates a PWM control IC. This paper describes the operation principle of the LED driver module and it is proved the usefulness through the real model with experimentation. Besides, this paper proposes the multi-channel LED driver which the miniaturized and modularized LED driver module are connected by parallel, and verified its propriety by experiments.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.243-249
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• 2018

In this paper, we analyzed the effect of modulation scheme and modulation scheme on the dimming level of visible light communication system and studied the effect of distortion due to delayed signal. Currently, the modulation schemes most commonly used in visible light communication result in increasing the communication performance but reducing the brightness of the entire illumination. Continuous Burst Zero Duration will severely degrade lighting. This degrades not only the illumination but also the performance of the whole system and causes Flicker phenomenon. In this paper, we analyze the relationship between modulation technique and illumination - communication performance and investigate the effect of signal delay on visible light communication system. Through simulation, we analyze the performance of IPI-OOK which has the best communication-lighting performance and propose future research directions accordingly.