Development of Mercury-free Light Source System

我们开发了无汞光源，不污染环境。我们用氙气的真空紫外线(VUV)辐射激发荧光粉，而不是汞原子的共振线。我们制作了真空紫外光谱测量系统，测量了氙气荧光灯的真空紫外光辐射，其中一个有内电极，另一个有外电极。当脉冲电压施加到灯上时，每个周期观察到两次辐射；当脉冲打开和关闭时，辐射发生。在内电极的情况下，真空紫外光在电流关断(余辉)后辐射，因此发现余辉有助于提高亮度和效率。通过求解被激发的氙原子的速率方程，发现控制余辉的衰减需要控制灯的内径和气体压力。进一步的分析，如研究VUV辐射与激发原子数的关系，发现通过减小外电极灯玻璃管的厚度来增加静电容量有利于提高亮度和效率。在内极灯的情况下，增加电极的数量以促进正柱的扩散是有利的。我们还试图改进电子镇流器；通过将普通电子镇流器中的两个以上的开关元件替换为一个开关元件来减少部件数量。因此，它能够减小电子镇流器的尺寸和重量。通过求解电路方程讨论了新型镇流器的特性，提高了小功率灯的亮度，如液晶显示器的背光，与汞荧光灯的亮度相同。但是，例如，在开发新的VUV源而不是氙气方面，通用灯的亮度和效率的进一步提高是必要的。

We have developed mercury-free light source, which does not pollute the environment. Instead of the resonance line of mercury atom, we employed vacuum ultraviolet (VUV) radiations of xenon to excite phosphor. We made a VUV spectroscopic measurement system and measured VUV radiations from xenon fluorescent lamps; one of them had inner electrodes and the other had external ones. When pulsed voltage was applied to the lamps, radiations were observed two times per period; when the pulse turned on and turned off, the radiations occurred. In the case of inner electrode, the VUV radiated after current turned off (afterglow), thus it was found that the afterglow contributed to improvement of luminance and efficiency. By solving rate equations of excited xenon atoms, it was found that to control inner diameter of a lamp and gas pressure was necessary to control decay of afterglow. Further analysis, for example, investigation of relations between VUV radiations and the number of excited atoms are necessary.It was found that increasing an electrostatic capacity by decreasing thickness of glass tube of an external electrode lamp was favorable to improvement of luminance and efficiency. In the case of an inner electrode lamp, increasing the number of electrodes to promote diffusion of positive column is favorable.We also tried to improve an electronic ballast; the number of parts was reduced by replacing more than two switching elements in a general electronic ballast with one switching elements. Thus, it is able to reduce the size and the weight of electronic ballasts. The characteristics of the new ballast were discussed by solving circuit equations.We improved luminance of low-power lamps, such as backlight of liquid crystal display, as much as that of mercury fluorescent lamps. But further improvement of luminance and efficiency is necessary for general-purpose lamps in terms of developing new VUV source instead of xenon, for example.