RLOD#37 (2020.06.25) 1990 Philips HPLR 1000W

Philips once produced a whole range of high-pressure mercury lamps designed for applications where lights needs to be directed more effectively than with a standard color-corrected lamps in reflector luminaires. A disadvantage of the fluorescent-coated bulb it that it greatly reduces the source luminance, which has a negative impact on the optical control of the emitted light in the case of isotropic emitters. Color-corrected mercury lamps thus introduced a tradeoff between light color quality and optical efficiency. Such limitation was resolved with the introduction of mercury lamps built with a phosphor-coated bulged-reflector bulb. For its HPLR Philips combined a layer of titanium dioxide and of yttrium vanadate phosphate borate phosphor, with the front part of the bulb left uncoated in the last variant of the lamp so as to prevent light scattering, which would widen the projected light beam. Another advantage of this lamp design is that its performances are mostly unaffected by dust accumulation, especially when used in the base up position, a characteristic that made it particularly useful for applications in the heavy industry. The HPLR 1000W presented here, shown in an early stage of its run-up phase, is the largest model produced by the Dutch. Characteristic of its high wattage, it features a three-piece arc tube provided with ignition probes at both ends. The latter feature ensures a reliable ignition under all conditions.