• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.237-240
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• 2002

A CCFL model for high frequency dimming electronic ballast simulation is presented in this paper. The model can be utilized for an electronic ballast simulation with continuous dimming and transient mode simulation such as step dimming. The piezoelectric transformer Is evaluated using an AC analysis. The electronic ballast composed of piezoelectric transformers and ZVS inverter was implemented. It enables a fluorescent lamp to be fumed on stably. Simulation of a high frequency electronic ballast which operates a fluorescent Imp at high frequency is proposed. Simulation is carried out using PSPICE program to illustrate the performance of the circuit

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1181-1183
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• 2003

Cold cathode fluorescent lamp(CCFL) are widely used to illuminate the liquid crystal display(LCD). Usually, CCFL dimming methods are used to lamp current regulation or average current adjust feeding the CCFL inverter. Switching frequency of inverter is higher than resonant frequency at stabile states. In this study, design of CCFL driving circuit by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output power. This method has advantages such as low EMI and reduced harmonics. And it is easy to dimming control use microprocessor. The validity of this study is confirmed from the simulation and experimental results.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.71-74
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• 2002

We have development the dimming controller using the ac chopper technique. The ac chopper change the amplitude of the input source voltage with the unchanged its frequency. The conventional dimming controller is operated by controlling voltage phase and is consist of the triac. It has a bad characteristic about a current THD and a power factor. But the dimming controller using the at chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the MOSFET and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.553-560
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• 2005

This paper presents a study on the dimming control of electrodeless fluorescent lamp. To do this the equivalent model of electrodeless fluorescent lamp (ENDURA 100w Type) was first established. The resulted model of the lamp was applied to the two kinds of dimming control method, one is the variable switching frequency method and the other is the variable dc link voltage method. And the comparison results of the dimming characteristics between the two methods was presented. Theoretical predictions were verified by the experimental results on the ENDURA 100W type electrodeless fluorescent lame.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.200-204
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• 2001

The high efficiency and high power inverter for driving LCD backlight was designed and fabricated. The operating frequency was variable and dimming capability was also included. High dimming ratio could be achieved by PWM dimming. The optimum driving condition for LCD backlight could be obtained by using the excited type inverter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2280-2288
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• 2014

The conventional dimming control methods of LED (Light-emitting dioades) include Analog, PWM (Pulse Width Modulation), and FM (Frequency Modulation) Control. Analog dimming is controlled by adjusting forward current of Power LED. Although Analog dimming is possible to control linearly the brightness levels on a whole range (0%~100%), it comes into existence a variation of wavelength by changing the Power LED's forward current. PWM dimming has achieved by varying in duty of full current flowing to the Power LED. Generally, PWM dimming doesn't make variation of wavelength but have difficulty with adjusting the linear brightness level between 0% and 10%. FM dimming method is on the same wavelength as PWM dimming, however, it has problem of flickering at low level of dimming. This paper propose a efficient dimming control method of Power LED in order to overcome the disadvantages of the above mentioned methods. We apply to Analog method in low level of dimming control and use PWM method in dimming range from 10% to 100%. For the experiment, we design and implement a circuit and test the proposed method. Consequently, we can control the linear brightness of Power LED across the whole range and get the constant wave at different dimming level. The experimental results show the benefits of the proposed method.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.67-73
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• 2011

Ceramic metal halide lamps have been widely used due to long lifetime, high luminous efficiency and good colour rendering. In this paper, we developed dimming control system of electronic ballast for 70W ceramic metal halide lamp by using 1-10V interface. The proposed electronic ballast is consists of EMI filter, Full-wave rectifier, Active PFC, DBI(Dual Buck Inverter), Igniter and control circuit.It enables to supply both low-frequency rectangular wave voltage and current to the lamp by using DBI(Dual Bcuk Inverter) structure. By using 1-10V interface, the system that able to dimming the lamp is demonstrated by P-spice simulation and experimental results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.313-317
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• 2004

This paper shows the structure of a control System for Fluorescent fin Dimming Ballasts. The control system is composed of phase angle controller, a transducer, many dimmable ballasts. For the implementation of the control system, We made a controller and the transducer that transform the phase angle controlled signal into the DC level. we used the conventional dimmable ballast In this ballast, dimming control is achieved by varying the switching frequency that is controlled by the external DC level. This has non-linear illumination characteristics as the dimming control. Therefore we compensate characteristics using the transducer proposed in this paper. We measured the illumination of two FL-28 lamps with dimming controller.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.269-275
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• 2021

Light-emitting diodes (LEDs) are modulated using a square wave pulse sequence for flicker prevention and dimming control in visible light communication (VLC). In a VLC transmitter, the high and low bits of the non-return-to-zero (NRZ) data are converted to two square waves of different frequencies, which continue for a finite time defined by the fill ratio in an NRZ bit time. As the average optical power was kept constant and independent of data transmission, the LED was flicker-free. Dimming control is carried out by changing the fill ratio of the square wave in the NRZ bit time. In the experiments, the illumination of the LED light was controlled in the range of approximately 19.2% to 96.2% of the continuous square wave modulated LED light. In the VLC receiver, a high-pass filter combined with a latch circuit was used to recover the transmitted signal while preventing noise interference from adjacent lighting lamps.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.30-36
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• 2022

In this paper, when the lighting and communication functions of the visible light communication system are used at the same time, we propose a technique to reduce the dimming level and flicker of the lighting. Visible light communication must satisfy both communication and lighting performance. However, the existing data code method results in reducing the brightness of the entire lighting. This causes deterioration of lighting performance and flicker phenomenon. To solve this problem, in this paper, we propose an adaptive learning code allocation technique that allocates binary codes to transmitted characters and optimizes and matches the binary codes allocated according to the frequency of occurrence of alphabets in character strings. Through this, we studied a technique that can faithfully play the role of lighting as well as communication function by allocating codes so that the 'OFF' pattern does not occur continuously while maintaining the maximum dimming level of each character string. As a result of the performance evaluation, the frequency of occurrence of '1' increased significantly without significantly affecting the overall communication performance, and on the contrary, the frequency of consecutive '0' decreased, indicating that the lighting performance of the system was greatly improved.