Philips TL-EM 40W Circline Fluorescent

Since the inception of the fluorescent lamp, its linear format has been regarded as an advantage in many applications - but in some cases has been a drawback. The first attempts to develop a more compact lamp can be traced to the invention of General Electric's Circline model in 1945. That was first offered in the 12" 32W rating, being joined by the 8" 22W in 1947, and the larger 16" 40W in 1952.

It did not take long for Philips to copy the bending process and commence production of its own circular lamps, known as TL-E, starting in 1950. Since Philips' first product was the 16" 40W model, produced 2 years before GE's launch, it is possible that Philips was the inventor of this rating.

In typical Philips fashion, this lamp is somewhat different than any other circline lamp in that it features a metal stripe painted along the entire length of the tube, and electrically connected to one electrode via a high resistance. In later models of this lamp the presence of the stripe was denoted by the addition of the letter M to the name TL-EM. The stripe consists of finely divided copper and silver particles in a glass frit that have been burned onto the surface of the tube. The purpose of this stripe was to simplify ignition so as to allow operation on Philips' favoured tungsten filament ballast lamps, instead of the usual magnetic ballast. A small transformer is necessary to provide continual heating of the electrodes. Philips luminaires for this lamp typically employed a crown silver incandescent ballast lamp mounted in a large reflector at the centre of the fluorescent circle. The Softone-32 colour is produced by a dual coat of calcium halophosphate and red-emitting magnesium fluoro-arsenate to produce warm white light of high CRI.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 40 Watts
Lamp Current: 0.42 Amps
Lamp Voltage: 110 Volts
Cap Type: G10q Phenolic Resin
Bulb Type: TC-28.5 TC-9 in eighths/inch
Bulb Finish: Softone-32 Lead-alkali glass
Electrodes: Triple Coil Tungsten BaCaSrCO3 emitter
Arc Length:
Atmosphere: Hg | Ar
Luminous Flux: 1750 lm (@ 100h) 1580 lm (average)
Luminous Efficacy: 43.8 lm/W (@ 100hrs) 39.5 lm/W (average)
Colour Temperature & CRI: CCT: 2900K CRI: Ra 87
Chromaticity Co-ordinates: CCx: 0.436 CCy: 0.405
Rated Lifetime: Not published
Warm-up & Re-strike time: 1 minute Instant
Burning Position: Universal
Dimensions: OD 403±8 mm, ID 339±4 mm OD 16 inch, ID 13.5 inch
Light Centre Length: N/A
Factory: Roosendaal Holland
Date of Manufacture: November 1956
Original / Present Value: GB £0 49s 2d (1955) GB £58.16 (2015)
References: 1) Philips Lamp Catalogue, UK, 1955.
2) Philips Lamp Catalogue, UK, 1957-58.