Thesis (M.S.)--University of Michigan, 1979.

No description available.

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.

No description available.

To minimize the size of the electronic ballast, a half-bridge load- resonant inverter with a cascading Rosen-type piezoelectric transformer (PT) is designed for cold cathode fluorescent lamps (CCFLs). The electrical characteristics of the PT are investigated to obtain a higher voltage gain by adapting the load impedance to the interposed network. The circuit parameters are selected under the considerations of (1) the minimum inductor size, (2) the higher circuit efficiency, (3) the rated current of the PT, and (4) the stable lamp operation. The electronic ballasts are designed for operating the lamp at the rated lamp power and with dimming control by asymmetrical pulse-width-modulation (APWM),respectively. Laboratory circuits are assembled and, experimental tests are carried out to validate the theoretical analyse

For a back-light module with multiple cold cathode fluorescent lamps (CCFLs) in mid-size or large size liquid crystal displays, a balance scheme must be included to have approximately equal currents among the lamps and hence to output equal brightness. In this thesis, a half-bridge inverter is adopted to drive multiple step-up transformers with the same turn ratio, in which the primary windings of the transformers are connected in series whereas the second windings drive CCFLs in parallel. Due to the series connection of the transformer sets, the current going through the primary windings is identical, so that the lamp currents from second windings tend to be equal. A driver circuit with the proposed scheme is designed for 8 U-type cold cathode fluorescent lamps in a 32-inch backlight module. The simulation and experimental results demonstrate the effectiveness of the balance scheme, even for the lamps operating at low current.

An introduction to the fundamental concepts of X-ray physics and X-ray tube design is given. This discussion also includes a brief description of various X-ray tube types available commercially for a number of different industrial applications. The design of a high-energy MgO cold cathode X-ray tube, which is to be used in an X-ray fluorescence (XRF) spectrometer, is described in detail with emphasis placed on the electron beam focusing mechanism and the theory of operation as well as the construction of the X-ray tube MgO cold cathode, which functioned as the electron emitter of the device. A detailed account is also given of the output characteristics of the X-ray tube power supply, which has a direct effect on the design requirements and consequently the performance of the X-ray tube. An investigation into the manufacture of the vacuum envelope with particular attention focused on the production of reliable metal-to-ceramic seals was performed. A number of tests were conducted especially with regard to the maximum temperature that such seals may withstand without becoming permanently damaged. These tests were essential, since high temperature gradients tend to develop in an X-ray tube during operation, which the metal-to-cerarnic seals of the tube must be capable of withstanding if damage to the device is to be avoided. The set-up of the XRF spectrometer in which the completed X-ray tube was tested is discussed, in which the X-ray current and voltage measuring techniques are described. Furthermore a detailed account of the operation of the X-ray detector system and the multichannel analyser is given, which was used to detect and record spectra of the sample elements excited by the primary radiation of the X-ray tube. Finally the measured X-ray tube performance characteristics are discussed and compared to the predicted results. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.

No description available.

No description available.