Philips Spotline NR60 Incandescent Double Reflector

In 1989 the Philips Spotline series of incandescent reflector lamps was introduced, and marked one of the most significant improvements in the five decades since original blown-bulb paraboloidal lamps were developed. It employs a novel double reflector concept to achieve a major increase in luminous intensity for a given flux and beam angle.

A drawback of conventional blown-bulb reflector lamps is that <40% of the filament's luminous flux impinges on the reflector surface. The rest exits uncontrollably via the front window of the bulb, or is lost backwards via the neck. As a result the intensification of light due to the reflector, i.e. the ratio of the lamp luminous intensity on the optical axis vs the filament luminous intensity in that direction, is typically only about a factor 10. The Spotline system increases the intensification to a factor 15-25 depending on the bulb diameter, thanks to the unique shape which controls 60% of the filament's luminous flux. The net result is a significantly brighter beam for the same luminous flux and beam angle.

Spotline lamps have superior reflectors designed with the entire filament length and shape in mind, whereas earlier lamps treated the filament as a theoretical point source. A key feature is the double reflector concept, where part of the bulb crown is coated so as to redirect to the main rear reflector light rays which would otherwise escape without control. Also the diameter of the transition to the bulb neck is narrowed, to reduce light loss towards the cap. Incidentally the groove shaped indent at this point was later dropped. Originally it had been intended to market some lamps with a metal anti-glare shield clipped to this part of the bulb, but that idea was never commercialised.
Manufacturer: N.V. Philips Gloeilampenfabrieken
Lamp Power: 40 Watts
Lamp Voltage: 240 Volts
Lamp Current: 0.17 Amperes
Cap Type: E27/27 Aluminium + Vitrite
Bulb Type: NR-60 NR-19 in eighths/inch
Bulb Finish: Internally Etched Aluminised Reflector
Filament Type: CC-9 Coiled-Coil Wreath
Atmosphere: 85:15 Argon:Nitrogen Approx 0.8 bar
Luminous Flux: N/A
Luminous Efficacy: N/A
Peak Intensity: 570 cd
Beam Distribution: 25° to 50% peak intensity
Colour Temperature & CRI: CCT: 2700K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.460 CCy: 0.411
Rated Lifetime: 1000 hours to 50% survival
Burning Position: Universal
Overall Length: 103 mm 4 inches
Light Centre Length: N/A
Factory: Weert Netherlands
Date of Manufacture: August 1989 Date Code H9
Original / Present Value: Unknown Unknown
References: 1) A System Approach to Incandescent Reflector Lamp Development, A.P. Gehring & P.A.J. Holten, Journal of the IES Summer 1990 pp.98-102.
2) European Patent EP0281185 "Electric Incandescent Lamp and Blown Glass Bulb Therefor", Petrus Holten, Philips 1988.
3) European Patent EP0284117 "Electric Incandescent Lamp and Blown Glass Bulb Therefor", Petrus Holten & Bob Roelevink, Philips 1988.
4) Philips Lighting UK Catalogue, 1991.