Philips UHP Mercury for LCD Video Projection

The introduction of the UHP lamp marked the advent of a new generation in digital projectors, and was one of the key enablers for the commercial success of these systems.

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:
References: 1) Photometric test December 2002