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Philips UHP Mercury for LCD Video Projection |
The lamp pictured here is the first generation device, and dates to 1995 when this concept was first commercialised by Philips. It is based on an extremely short mercury arc operating at immensely high pressures. The short arc is of importance to ensure high efficiency collection of the light, and focussing by the reflector into the optical system of the projector. It is this short arc which has been responsible for the recent increase in projector screen lumens
Similarly the very high mercury pressure is of importance to achieve a suitable spectral power distribution. The mercury spectrum is usually lacking considerably in red radiation, but when the pressure is increased, a considerable portion of continuum radiation is generated. This depends very strongly on the mercury pressure. Typical lamps operate at pressures of the order of 200 atmospheres. Dropping to 160 bar results in a 20% decrease in red radiation.
The electrodes are made from pure tungsten, with balled ends bearing a small protruberance at the tip. This is actually molten during operation, the high temperature being required to achieve a stable arc root without flicker. To prevent arc tube blackening, a halogen cycle is used.
Lamp failure occurs only as a result of devitrification of the extremely highly loaded quartz arc tube. This effect contributes to a gradual light output depreciation over lamp life, as the effective source size becomes greater.
| Manufacturer: | Philips Lighting | |
| Lamp Power: | 120 Watts | |
| Lamp Current: | 2.0 Amps | |
| Lamp Voltage: | 60 Volts | Ignition ~ 6kV |
| Cap Type: | Screw lugs | |
| Bulb Finish: | Hard dichroic cold mirror | Borosilicate glass |
| Bulb Type: | Ellipsoidal750mm | PDR-23 (in eighths/inch) |
| Overall Length: | ||
| Light Centre Length: | ||
| Arc Length: | 1.0 mm | |
| Electrodes: | Solid tungsten | |
| Inner / Outer Atmosphere: | Ar | Hg + Br | |
| Luminous Flux: | 7000 lm | |
| Luminous Efficacy: | 58 lm/W | |
| Colour Temperature & CRI: | CCT: 7600K | CRI: Ra 57 |
| Chromaticity Co-ordinates: | CCx: 0.298 | CCx: 0.311 |
| Burning Position: | Beam Horizontal | |
| Rated Lifetime: | 2000 hours | |
| Warm-up / Re-strike Time: | 30 seconds | Instantaneous |
| Factory: | Turnhout | Belgium |
| Date of Manufacture: | October 1995 | |
| Original / Present Value: | ||
