The energy loss of an electronic ballast is mainly composed of switch loss and inductor loss. The loss decreases when setting the component values so as to reduce the phase angle of the load circuit. However, the lamp current limitingaction falls and fails to stably operate the lamp. We have examined the ways to improve the control stability by using the loop transfer function, the bode plot in particular. By designing a control circuit with the experimentally measured looptransfer function and the transfer function of each functional circuit block, the tested lamp was able to operate stably.
The mechanism that causes the end of lamp life (EOLL) phenomenon in a fluorescent lamp should be clarified to better understand the EOLL. The phenomenon, including the tungsten sputtering from an electrode, is investigated. We observed the electron emission from a lead in the vicinity of the stem glass resulting in the intermittent pulse discharge that heated up the stem glass. The comparison of the stem glass resistance and the glow discharge impedance at an interval of leads after disconnection of the filament indicates whether or not the stem glass will begin to soften. It was shown that the heating of a small glass portion around the lead by the intermittent pulse discharge or the concentration of discharge current into one of leads was a dominant factor that resulted in the final stage of EOLL.
Super high pressure mercury discharge short arc lamps have been used as light sources for photolithography, such as patterning LCDs, PCBs and semiconductors. Normally, their bulbs are made of silica glass. This study evaluates optimal shapes for various lamp bulbs under internal pressure using the Finite Element Method (FEM). We obtained an optimal shape and the relationship between the fracture stress and the bulb thicknes. The optimal shape was obtained at 0.7≤D/L≤0.9, where L is the total length of the bulb and D is the diameter. To verify our computed results, we conducted static water pressure tests. We found simularities between the numerical results and experiments.
Visual experiments on the Borderline between Comfort and Discomfort (BCD) luminous intensity were carried out to clarify the characteristics of discomfort glare caused by multiple point sources in a row and in a matrix. The experiments were done under conditions of dark adaptation, varying the number and interval of the sources. The results show that the increase in BCD luminous intensity is smaller than that in the number of the sources, although BCD luminous intensity increases as the number of the sources increases. The condition of multiple point sources in a row on discomfort glare is obtained in the virtual area. The BCD luminous intensity of multiple point sources in a row is lower than that of linear source, even if the interval is narrow.