Generally, high-pressure mercury lamps are used as the light source for projectors. This comparatively large-size and low luminosity light source is sealed by a reflector and a front glass, similar to that used as the light source for projection TVs. However, the light source used for front projectors, which needs to be small and to have high luminosity, is not sealed very well. When a luminescence pipe explodes, it is difficult to prevent a non-sealed light source from scattering mercury and shattered glass inside the projector. We studied a small, sealed, and highly luminos light source for projectors. About 130W is the input limit for a sealed light source for projectors because of the problem of luminescence pipe cooling. However, we found a way to build a high luminosity, small-size, and sealed light source by developing a reflector with a four layer structure.
To improve the efficiency of the cold cathode lamp (CCL), it is important to select the optimum electrode material to reducing the cathode fall voltage (CFV). Furthermore, it is necessary to understand the relationship between the electrode material and the CFV. Considering the above, we measured the CCL’s CFV with an indirect CFV measurement method using a hot cathode fluorescent lamp. By observing the negative glow of the electrode, we investigated the relationship between the CFV and the negative glow condition. The results showed that there is a relationship between the CCL’s CFV and the γ coefficient of the electrode. Moreover, they make it clear that there is a relation between the CFV and the negative glow condition of each electrode material. We conclude that the CFV measurement method is useful for estimating the performance of a CCL’s electrode.
In our previous study, we described an index, N × LC, for luminance distribution that is suitable for estimating the impression of active-calm of a lighting space. The previous experiment was carried out in the space whose interior was uniform white, and thus indicates that luminance distribution was approximately equivalent to light distribution. Interiors of actual rooms, however, are generally constructed with a range of reflectances. We focused on the practical application of the index; we carried out an experiment to measure the impression of active-calm in a space whose interior was composed of several objects with different reflectances and examined the effect of the light distribution and the composition of the interior reflectance. The results showed that the light distribution had a significant effect on the impression of active-calm. In addition, the interaction between the light distribution and the reflectance composition was not statistically significant. On the basis of these results, we considered the applicability of the N × LC index.