RLOD#24 (2020.05.30) 2010 Philips UHP 300W 1.3

The application of mercury arcs to image projection was an obsession at Philips ever since the company's invention of the superatmospheric quartz mercury lamp in 1935 (the HP and SP). However, these sources’s biggest limitation lies in their poor light color quality that arises from a characteristic lack of red emission. Increasing pressure improves the light color to some extent, but technology prevented a stable and durable operation above 80 bars, which was not enough to achieve a proper white-light emission. To remedy this, Philips introduced its SPP pulsed-power system in the late 1930s, which was somewhat successful in motion picture projection until Osram released the first xenon short-arc lamp (XBO) in 1952. GE’s introduction of the first metal halide arc lamp (MARC) in 1965 pushed pure mercury sources further away from color film projection applications.

It is only in the early 1990s that Philips managed to design the first practical white mercury arc source using ultrapure quartz, cutting edge manufacturing techniques, and a refined argon-bromine-mercury fill chemistry. The new lamp featured a very short arc of around 1 mm burning in 200 bars mercury, resulting in a compact luminous plasma having an extremely high luminance (> 1 Gcd/m²), free of the chromatic segregation usually found in metal halide sources, all combined with a lumen efficacy higher than that of xenon arc lamps (55‒65 vs. 10‒29 lm/W in the 50‒450 W range). This breakthrough led to the 120 W Ultra High Performance (UHP) lamp released in 1994. This highly successful concept resulted in a wide variety of lamps which redefined the commercial and home video projection markets. However, the movie theater business remained out of reach because reliable UHP sources could not be made beyond 465 W.