GE Miser BR30 Blown Bulb Reflector

In 1985 GE developed the first in a series of reflector lamps having a moderately improved optical profile so as to increase the useful light output. Known as the BR-shape reflector lamp, it is successful in raising the optical efficiency by about 10% above the standard R-shape lamps.

A number of design features are incorporated into the BR shape lamps. Firstly and of most significance, the diameter of the neck section which connects the bulb to the cap is reduced to minimise the quantity of light rays lost in a backwards direction. Secondly the former single reflector is replaced by a two-part optical surface, by adding a small secondary confocal paraboloid at the transition fillet between the main reflector and the bulb neck. Light rays impinging on this region of the bulb in an ordinary lamp tend to be reflected at a wide angle, and may not contribute to the useful output. However in BR lamps, rays striking the secondary reflector are redirected back towards the main reflector, and effectively collimated into the useful forward beam. Thirdly, the depth of the reflector is greater than in standard lamps. By flattening the curvature of the light emitting area of the bulb crown, a greater reflective surface is available and this affords a further increase in efficacy. Fourthly, a metal heat-shield is strategically positioned in the bulb neck to capture and reflect into the useful beam other light rays that would normally be lost towards the cap.

The approximate 10% efficacy improvement of BR reflectors has been translated into a range of lamps having 10% reduced power consumption for the same light output. In view of the performance advantage, standard R-lamps have begun to be phased out by government legislation in USA.
Manufacturer: General Electric USA
Lamp Power: 45 Watts
Lamp Voltage: 120 Volts
Lamp Current: 0.375 Amperes
Cap Type: E26/25 Aluminium + Vitrite
Bulb Type: BR-95 BR-30 in eighths/inch
Bulb Finish: Inside Frosted Aluminised Reflector
Filament Type: CC-6 Coiled-Coil Transverse
Atmosphere: 85:15 Argon:Nitrogen Approx 0.8 bar
Luminous Flux: 485 lumens
Luminous Efficacy: 10.8 lm/W
Peak Intensity: 300 candelas
Beam Distribution: 30° to 50% peak intensity
Colour Temperature & CRI: CCT: 2700K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.460 CCy: 0.411
Rated Lifetime: 2000 hours to 50% survival
Burning Position: Universal
Overall Length: 136.5 mm 53/8 inches
Light Centre Length: 77.8 mm 31/16 inches
Factory: Ohio Lamp Plant, Warren U.S.A.
Date of Manufacture: January 1994
Original / Present Value: Unknown Unknown
References: 1) GE Lamp Catalogue, USA, 1996, p.1-12
2) GE Lamp Catalogue, USA, 1991, p.18
3) US Pat 4,536,834 "R Lamp Having Improved Neck Section for Increasing Useful Light Output", Bloom, Buccilli & Belentepe, GE Lighting, Filed 1984
4) US Pat 4,656,386 "R Lamp Having Improved Dome Portion for Increasing Useful Light Output", Bloom, Buccilli & Belentepe, GE Lighting, Filed 1985
5) A New Reflector Lamp having a Secondary Confocal Paraboloid at the Transition Fillet, Lighting Design & Application, December 1985, pp.44-47