Three programmed rapid-start control schemes for the electronic ballasts with a half-bridge series-resonant inverter are proposed to improve the starting performance of the rapid-start fluorescent lamps. Included are: (1) programmed rapid-start control scheme with an ac switch, (2) programmed rapid-start control scheme with inductively coupled filament-heating circuit, and (3) programmed frequency control scheme with a series-resonant energy-tank. The first control scheme is simply to add a solid-state ac switch onto the series-resonant electronic ballast to provide programmed rapid-start for the rapid-start fluorescent lamp. The ac switch is turned on to have a zero voltage across the lamp to eliminate the glow current during the preheating interval. By adjusting the operation frequency and the duty-ratio, the electronic ballast produces first an adequate resonant current for preheating the cathode filaments, then a sufficiently high lamp voltage for ignition, and finally a stable lamp arc of the required lamp power. The second control scheme is accomplished by adding two auxiliary windings on the inductor of the power-factor-correction (PFC) circuit for the filament-heating circuits. During the preheating period, the PFC circuit is activated to provide the filament heating while the inverter remains idle to keep the lamp voltage at zero and hence to eliminate the glow current. After the filaments have been heated to the appropriate temperature, the inverter is initiated to ignite the lamp and then operate it at the required power. The third control scheme is realized by programming the operation frequency of the electronic ballast with an additional series-resonant energy-tank on the load resonant network. During the preheating interval, the electronic ballast is programmed to operate at the resonance frequency of the series-resonant energy-tank to reduce the lamp voltage and hence to eliminate the glow discharge. With carefully designed circuit parameters, the electronic ballast is able to provide an adequate current for preheating. After the emission temperature has been reached, the operation frequency is adjusted to generate a high lamp voltage for ignition, and then is located at the steady-state frequency driving the lamp with the desired power and filament current. In this dissertation, the mode operations of the proposed ballast circuits are analyzed in accordance with the conducting conditions of the power switches. The equivalent resistance model of fluorescent lamp is implemented to calculate the performances of the ballast-lamp circuit at steady-state. The design equations are derived and the computer analyses are performed with the fundamental approximation on the equivalent circuit models of fluorescent lamps. In addition, in order to accurately predict the operating characteristic of the preheating circuit, a mathematical model is developed to interpret the variations of the filament resistance during preheating. Finally, the laboratory electronic ballasts with the proposed control schemes are built and tested. Satisfactory performances are obtained from the experimental results.

The fault phenomena of fluorescent lamps are investigated by observing the operations in the last period of the life cycle. Accordingly, fault detecting and protection circuits are designed. Before coming to the life-end, the lamps can be started up, but are operated abnormally. A ruddy glow may occur at one end of the cathode filaments and an unstable arc may happen to the lamp. Obviously, the light efficiency becomes relatively low. The arc instability eventually results in a totally damaged fluorescent lamp. It is found that both waveforms of the lamp voltage and the lamp current are asymmetrical and have unequal positive and negative peak values. The asymmetry is more significant for the lamp voltage. In addition, a dc component is present in the lamp voltage. Based on these investigated results, the detection and protection circuits are designed for high-frequency electronic ballasts under dimming operations as well at the rated power. The experiments show that the detection and protection circuits can work effectively.

Fluorescent lamps with ac current generate alternating lamp power and thus the light fluctuates at twice the operating frequency. To observe the light fluctuation from a fluorescent lamp, a light detector is built by using high sensitivity phototransistors in this thesis. The test results show that the light output waveform is very similar to that of the lamp power. It is also found that the light output from the whole lamp tube is not identical because the light output fluctuation becomes significant when close to the end of the lamp. When the lamp comes to the life-end, its light output is different from those produced by lamps of good conditions. In attempts to further discuss the features of light fluctuation, an electronic ballast with balanced multi-phase outputs is designed and built to reduce the variation in the light output. With a balanced multi-phase operation, the resultant light output from lamps¡¦ multi-phase currents should be a constant. An experimental 3-phase electronic ballast circuit is built to test this theoretical prediction. Experimental tests confirm that the light fluctuation can be effectively reduced by operating lamps with balanced multi-phase currents.

A robust design utilizing consecutive orthogonal arrays algorithm is proposed for designing electronic ballasts of fluorescent lamps. By this design method, the variation in the lamp power can be less than 10% under different operating conditions. In the manipulation of the consecutive orthogonal arrays, component values of the ballast circuit and DC-link voltage are used as controllable variables for inner orthogonal arrays; while manufacturers, ambient temperature, used hours, and variation in DC-link voltage are treated as uncontrollable variables for outer orthogonal arrays. The average effects of the output power for each controllable variable are calculated from simulation results, which are served as indexes to find the combination of circuit parameters with a better solution. With consecutive orthogonal arrays, the target values of the circuit parameters are approached step by step. In addition, the effect of the DC-link voltage on the lamp power can be understood from the uncontrollable variable of outer orthogonal arrays. The proposed design tool is implemented on the design of an electronic ballast for a 40W fluorescent lamp. The test results show that the designed electronic ballast can be adopted for the lamps from different manufacturers, with different used hours, and under variation in a wide range of ambient temperature.

Fluorescent lamps are nowadays the most important light sources in industrial, commercial, and domestic applications. To drive fluorescent lamps, electronic ballasts with high-frequency resonant inverter, instead of the electromagnetic ones, are increasingly used due to the benefits of lightweight, small size, high luminous efficiency, and long lamp life. Recently, efforts are concentrated on how to reduce the product cost as well as to improve the circuit performances. To further curtail the product cost, the power-factor-correction circuit is integrated into the ballast circuit as single-stage high-power-factor electronic ballast. On the other hand, the unit cost per lamp can be substantially reduced by developing a ballast circuit which is capable of driving multiple lamps. For convenient use, the user may turn on the desired number of the lamps in accordance with the expected luminosity. A starting-aid circuit is added to eliminate the glow current during preheating. In addition, a protection circuit will be included in the multi-lamp electronic ballast. In case of operating partial lamps, a high power factor at the line input will be always retained. In this thesis, the feasible circuit configuration is developed and design equations are derived. Accordingly, design guidelines for determining circuit parameters are provided. The laboratory circuits are built and tested to verify the computer simulations and analytical predictions.

A new starting profile, instead of ANSI C82.11, is defined to illustrate the starting transient of rapid-start fluorescent lamps driven by high-frequency electronic ballasts. By scrutinizing the lamp voltage and current waveforms, the starting transient can be classified into preheating, glow, and glow-to-arc stages. By the new definition, the starting characteristics of all ballast-lamp circuits can be well interpreted. To investigate the starting performance, a test system is set up. Experimental results show that the time required for glow and glow-to-arc stage is significantly affected by the starting voltage, the filament preheating and the environment temperature. On the basis of the in-depth analysis on the investigated results, the starting characteristics of rapid-start fluorescent lamps are well understood, providing useful information for designing the starting scenario for the ballast.

In this thesis, a high voltage discharging testing circuit is proposed for cold cathode fluorescent lamps(CCFLs). The testing circuit uses only a single active power switch operating at a high frequency incorporating with reactive components to accumulate a relatively high voltage on the capacitor. This voltage is then stepped up by a transformer to provide the required high voltage for discharging the CCFLs. The circuit has the advantages of simple configuration, less component count, and low cost. In addition, a high power factor at the ac line source can be achieved. The proposed circuit is analyzed based on the mode operation. Accordingly, the design equations are derived to determine the circuit parameters. A prototype is designed and built for testing the 19 inch CCFLs. The discharging tests are made to recognize the malfunctions during the manufacturing process. Moreover, the distributions on the spectral power and chromaticity of lamps can be examined to ensure the product quality.

The liquid crystal display is high light, the advantage thin in thickness. In order to reach the thickness thinly, the request good in degree of consistency, it is important to design a qualified mould group in a poor light. This text introduces how to utilize Trace Pro optics to imitate the software , imitating to the diffusion board of the mould group in a poor light of the liquid crystal display , analysis and designing mainly. To the sidelight type mould group in a poor light, go to type in a poor light mould group construct comparatively simple , main optics for reflect board , spread scene , cold cathode tube and arris lens component its directly. The main use of reflection board lying below the mould group among them , in order to collect and reflect the light that come from the light source, make it penetrate above to in a poor light mould group, in order to increase the luminance of screen. Spread slice and function , arris of lens and the arris lens like mere sidelight type in a poor light mould diffusion slice of group, make their even to take in order to raise the luminance of screen light scattering separately. When the mould group in a poor light is thinner and thinner in thickness, brightness its disparity can more and more heavy too, so optics design more and more challenging. This text designs mainly to spread the distribution that the board adds the particle son to with the high degree of consistency, is it probe into in a poor light mould light neat degree that group can appear to come. Design a series of and reply the mould group which reflect the array, software Trace Pro is enabled being used for designing and replying the geometry structure which reflects the array and shut in the simulation optics route , analog quantity examines the result designed, and discuss its characteristic.

This thesis investigates the impact of preheating and glow current on the life-time of rapid-start fluorescent lamps during the starting transient period. A set of electronic ballast circuit is designed to adjust the starting transient preheating current, open-circuit voltage, and preheating time, so that the preheating conditions and the intended amount of glow current can be scheduled. In the experiments, the tested lamps are frequently switched on and off for 35 seconds and 25 seconds, respectively, to accelerate the life-cycle test. Experimental results show that the effect of the glow current on the life-cycle is trivial. Insignificant difference is found between the test lamps with different glow currents when the preheating conditions are the same. On the other hand, the preheating degree is found to be the main factor that affects the lamp life-time. The tested lamps which are adequately preheated last for more than 100000 test cycles. On the other hand, the tested lamps with insufficient preheating are premature with black ends or even damaged only after the several thousands cycles.

Term project on comparison of conventional light bulbs and light sources present in terms of mutual compensation marks dissertation, which will pay the same issue. The main pillar of the thesis will be a practical measure, whose structure is indicated below. Semester project constitutes a theoretical basis for a thesis and provides an overall introduction to the issue of compensation light sources. Emphasis is placed on the differences between the light source and the real problems may be encountered by consumers during the transition to another type of light bulbs, respectively. fluorescent lamps. Because consumers often replace the original lamps with compact fluorescent lamps, semester project pays attention to just the differences between ordinary incandescent and energy-saving fluorescent lamps.