Philips Halogen Dichroic Reflector MR16 Square

In 1990 Philips took a novel departure from established practice with the introduction of this square lamp. At the time Philips had limited facilities for halogen MR16 lamps, favouring its aluminium reflector concept. It was becoming clear that consumers did not share that view, and the MR16 business boomed while the AR market stagnated. To catch up and win back market share from competitors that had been quicker to act, Philips had to do something special.

Philips in Europe developed the outstanding "Masterline" lamps, making up for a decade of absence by surpassing competitor's MR16 performance. Meanwhile Philips USA developed this ingenious square lamp. For any reflector lamp, optical performance increases when the light source is as small as possible and the reflector is as large as possible. In this lamp the optical diameter is about 15-20% larger than round MR16 lamps, but parts of the reflector rim that would fall beyond the MR16 diameter are cut away. Despite this loss in a less important part of the reflector surface, the change of profile in the deeper part of the reflector yielded a major improvement in light-collection efficiency.

The range of 20W, 39W and 49W square lamps was introduced as an energy-saving concept, having similar luminous intensities as 35W, 50W and 75W round lamps. Despite the technical advantage, consumers did not embrace the odd-looking concept of a square lamp in existing round luminaires. In 1993 they were replaced by the Philips European Masterline lamps, which achieved their performance increase by other methods. Philips did however retain the concept of the optically superior square reflectors for its UHP lamps used in television and data projectors.
Manufacturer: Philips Lighting
Lamp Power: 49 Watts  
Lamp Voltage: 12 Volts  
Lamp Current: 4.08 Amperes  
Cap Type: GX5.3 Glass 2-pin
Bulb Type: SQ-51 SQ-16 in eighths/inch
Bulb Finish: Borosilicate Glass Dichroic reflector
Filament Type: C-6 Transverse Single Coil
Atmosphere: Bromine, Krypton
Luminous Flux: N/A  
Luminous Efficacy: N/A  
Luminous Intensity: 4,800 cd  
Beam Distribution: 24° to 50% peak
Colour Temperature & CRI: CCT: 3000K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.452 CCy: 0.409
Lifetime: 3500 hours to 50% survival
Burning Position: Universal  
Overall Length: 45 mm 1 3/4"
Light Centre Length: N/A  
Factory: Richmond, KY U.S.A.
Date of Manufacture: August 1990 Date Code: 0H
Original Value: US $15.42  
References: 1) Philips Catalogue SAG-100, 1991 USA, pp.20 & 55
2) Philips Price List PS-101-U, 1991 USA, p.23
3) Philips Catalogue SAG-100, 1993 USA
4) Philips Price List PS-104-EXD, 1993 USA, p.9
5) Philips Brochure, Masterline Square, 1991 USA
6) Lighting Design & Application, November 1990, p.10