||The first blown-bulb 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 similar beam angles 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 large 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 luminaire without impinging on its sidewalls and being lost.
The ER lamp achieved tremendous success in the USA, however in Europe the downlight is used to a much lesser extent. 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 the production was stopped.