• Journal of Power Electronics
• /
• v.3 no.3
• /
• pp.175-184
• /
• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is Introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and also voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E Inverter is used In this paper. The proposed PFM control scheme didn't use any auxiliary circuit. The proposed control strategy is executed by feeding back the Input voltage, and the zero-voltage-switching (ZVS) is ensured by maintaining constant turn-off time of the switch Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulations and experimental results.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.1 no.2
• /
• pp.49-56
• /
• 1987

To save energy consumption, it is proposed to operate a discharge lamp with high frequency power. When designing a high frequency operating circuit containing a discharge lamp, the character of a lamp may be needed. And there are various methods to get and models for this. In this study, to present the volt-ampere character of a fluorescent lamp which gives a good saving effect, the nonlinear resistance model is suggested. And the validity of the model is verified by applying the model for the circuits with inductor ballast and capacifor ballast. This model, in contrast with the others, can be easily obtainable. And for comparison, the model using a modified Francis equation is examined. The method used in this study can be basically applied to the other discharge lamps. As a result, 1) Approximated 3rd order polynomial of nonlinear resistance model gives a good simulation result. 2) When operating in high frequency, the model using a modified Francis equation with constant coefficients can't be applied.

• Proceedings of the KIEE Conference
• /
• 2008.10c
• /
• pp.126-128
• /
• 2008

This paper presents an architecture for driving multiple paralleled cold cathode fluorescent lamps (CCFLs) for back lighting applications. Multi CCFL operation and increase of brightness, the key to the architecture is a proposed capacitive coupling approach for lamp ignition. This system is consist of a flyback converter, a single inverter to drive multiple lamps and conductive floating reflector. The topology is capable of driving a number of parallel lamps with independent accurate lamp, The capacitive coupling the leakage inductance and stray capacitance creation which it used, current regulation and improving cost effectiveness with significant reduction in size and weight, compared to typical high frequency ac ballast. Experimental demonstration results for ten of parallel CCFLs with simultaneous ignition.

• Proceedings of the KIPE Conference
• /
• 2004.07a
• /
• pp.163-166
• /
• 2004

The conventional fluorescent lamp dimming system using an another control line is complex and will increased the cost. Therefore, many studies have focused on the wireless communication, but it is not fit for dimming system because of the interference generated by the infra-red light of lamp or switching noises in ballast. So, we applied the power line communication on the dimming system and we proposed a new coupling circuit using the voltage controlled impedance convertor for improving the performance of the FH/SS PLC modem. The performance for the proposed modem is evaluted by the BER.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.05a
• /
• pp.484-488
• /
• 2000

This paper proposes a highy efficient inverter circuit for fluorescent lamp inverters using two state capacitors. A waveform of full-wave rectification used as a direct current power supply at fluorescent lamp inverters contains a lot of harmonic wave from inrush current which is generated near the maximum of input voltage with purse shape when voltage smoothing capacitor is charged. Therefore, In order to suppress inrush current which will result in harmonic wave, This paper proposed a method to control abrupt charging current by use of charging voltage at pre-state capacitor. As the result of it, power factor comes to be improved through the suppression of harmonic wave generation at supply current. Validity as to this experiment is confirmed through simulation.

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

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.4
• /
• pp.161-164
• /
• 2006

In this thesis we designed the vision system to inspect the defect of a back light unit of plat panel display device. The vision system is divided into hardware and inspection algorithm of defect. Hardware components consist of illumination part, robot-arm controller part and image-acquisition part. Illumination part is made of acrylic panel for light diffusion and five 36W FPL's(Fluorescent Parallel Lamp) and electronic ballast with low frequency harmonics. The CCD(Charge-Coupled Device) camera of image-acquisition part is able to acquire the bright image by the light coming from lamp. The image-acquisition part is composed of CCD camera and frame grabber. The robot-arm controller part has a role to let the CCD camera move to the desired position. To take inspections of surface images of a flat panel display it can be controlled and located every nook and comer. Images obtained by robot-arm and image-acquisition board are saved on the hard-disk through windows programming and are tested whether there are defects by using the image processing algorithms.

• Proceedings of the KIEE Conference
• /
• 1999.07f
• /
• pp.2783-2785
• /
• 1999

A fast switching gate driver suitable for high performance self resonant electronic ballasts is presented. The proposed gate driver has negligible switching loss and driving loss owing to pnpn structure and zero voltage switching( ZVS ); moreover, the gate driver has frequency control capability. Therefore, a self resonant inverter using proposed gate driver can operate as external exciting resonant inverters. The experiments confirm that the proposed gate driver perform the desired operations over full power control range for 40W fluorescent lamp electronic ballast.

• Journal of the Korean Vacuum Society
• /
• v.17 no.4
• /
• pp.331-340
• /
• 2008

A method of measuring the current and voltage is suggested in the circuit of cold cathode fluorescent lamps (CCFLs) which are driven at a high frequency of $50{\sim}100\;kHz$ and a high voltage of several kV. It is difficult to measure the current and voltage in the lamp circuit, because the impedance of the probe at high voltage side causes the leakage current and the variation of luminance. According to the analysis of equivalence circuit with the probe impedance and leakage current, the proper measuring method is to adjust the input DC voltage and to keep the specific luminance when the probe is installed at a high voltage circuit. The lamp current is detected with a current probe or a high frequency current meter at the ground side and the voltage is measured with a high voltage probe at the high voltage side of lamp. The lamp voltage($V_C$) is measured between the ballast capacitor and the lamp electrode, and the output voltage($V_I$) of inverter is measured between inverter output and ballast capacitor. As the phases of lamp voltage($V_C$) and current ($I_G$) are nearly the same values, the real power of lamp is the product of the lamp voltage($V_C$) by the lamp current($I_G$). The measured value of the phase difference between inverter output voltage($V_I$) and lamp current($I_G$) is appreciably deviated from the calculated value at $cos{\theta}=V_C/V_I$.

• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.234-236
• /
• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E inverter is used in this paper The proposed PFM control scheme doesn't used any auxiliary circuit. The proposed control strategy is executed by feeding back the input current. and the Zero-Voltage-Switching (ZVS) is ensured by operating beyond resonant frequency. Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulated results.