Sylvania Ellipsoidal Reflector ER95
The first blown-bulb incandescent reflector lamps were introduced in 1936, following their invention by Royal Strickland of GE's Large Lamp Department. During the next four decades these so called R-lamps were the workhorses of accent and display lighting, and subequently earned popularity when recessed deeply into new low-glare track and downlight luminaires during the boom of these fixtures in the 1970s.

Around this time another GE engineer, Frank LaGiusa astutely recognised that a significant proportion of their light was being wasted and absorbed by the interior side walls of these recessed luminaires. He solved this problem with his invention of the so-called ER or Ellipsoidal Reflector lamp.

Although naked ER and R lamps achieve a similar beam angle and photometric performance, the difference when installed in a recessed luminaire is so profound that a 75W ER95 / ER30 lamp can achieve the same output as a 150W R125 / R40. With the R-type parabolic reflectors, the divervence of the light rays begins immediately in front of the bulb and a significant proportion of output is absorbed by the black interior of the luminaire. However with an ER lamp the light rays are focussed to a point two inches ahead of the bulb centre before diverging. This efficiently allows light out of a deep recessed luminaire without impinging on its sidewalls and being lost.

The ER lamp achieved tremendous success in the USA where such fixtures continue to be very popular. In Europe the downlight is used to a much lesser extent, but nevertheless in 1980 a high voltage version was introduced by American manufacturer GTE Sylvania. Inevitably the demand for such a lamp in Europe was minimal and by 1987 production ended.
Manufacturer: GTE Sylvania
Lamp Power: 75 Watts  
Lamp Voltage: 240 Volts  
Lamp Current: 0.31 Amperes  
Cap Type: E27/27 Brass + Vitrite
Bulb Type: ER-95 ER-30 in eighths/inch
Bulb Finish: Inside Frosed Aluminised
Filament Type: CC-9 Coiled-Coil Wreath
Atmosphere: 87% Argon 13% Nitrogen
Luminous Flux: N/A
Luminous Efficacy: N/A
Peak Intensity: 750 cd
Beam Distribution: 35° 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: 135 mm 6½ inches
Light Centre Length: N/A
Factory: Lyon France
Date of Manufacture: circa 1985
Original / Present Value: Unknown Unknown
 
References: 1) US Patent 4,041,344 "Ellipsoidal Reflector Lamp", Frank LaGiusa, General Electric Co. U.S.A.