Philips "TL"W 25W W-shaped Fluorescent
Since the inception of the fluorescent lamp, its linear format has been a great advantage in many applications - but in some cases has also been viewed as 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, copied by Philips' TL-E series in 1950. Later developments led to U-shaped lamps by the German firms Osram and Narva. These were also copied by Philips TL-U series, but Philips did not succeed to break the German domination and soon abandoned its production and sourced from Osram.

During the 1960s there were ambitions to produce flat square luminaires of equal aspect ratio, with a uniformly lighted front panel. Circline lamps had the drawback that they left a dark patch at the centre and corners of the luminaire, which could be partially improved by mounting a small diameter lamp within a larger one, but this led to expensive designs that often delivered too much light. U-tubes had the similar drawback that two or three had to be used side by side to achieve a uniformly lighted panel.

Philips' solution was this unique TL-W lamp, introduced in 1964, with the aim of achieving even luminance across the face of compact square luminaires. The lamp was expensive however, and the market proved to be not large enough to justify its continued production. It was discontinued in 1977. Like the U-tubes it is notable for its great weight, having been made from thick-walled lead glass tubing, this material being easier to bend into a tight U-shape than ordinary glass types. 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: 25 Watts
Lamp Current:
Lamp Voltage:
Cap Type: 2x G13 Nickel Plated Brass + Philite
Bulb Type: TW-27 TW-8.5 in eighths/inch
Bulb Finish: Softone-32 Lead-alkali glass
Electrodes: Triple Coil Tungsten BaCaSrCO3 emitter
Arc Length:
Atmosphere: Hg | Ar
Luminous Flux: 900 lm (@ 100hrs)
Luminous Efficacy: 36.0 lm/W (@ 100hrs)
Colour Temperature & CRI: CCT: 2900K CRI: Ra 87
Chromaticity Co-ordinates: CCx: 0.439 CCy: 0.400
Rated Lifetime: Not published
Warm-up & Re-strike time: 1 minute Instant
Burning Position: Universal
Overall Length: 257 x 259 mm 101/8 x 103/16 inches
Light Centre Length: N/A
Factory: Roosendaal Holland
Date of Manufacture: May 1967 Date Code: E7
Original / Present Value: GB £0 20s 0d (1964) GB £16.80 (2015)
 
 
References: 1) Philips Lamp Catalogue, UK, July 1964, p.A37.
2) Philips Lamp Catalogue, Australia, c. 1960.
3) 50 Jaar Philipslicht in Roosendaal 1948-1998, publ. Philips Licht Roosendaal 1998, pp. 27 & 34
4) 60 Jaar Philips Roosendaal 1948-2008, publ. Philips Licht Roosendaal 2008, p. 66.
5) Philips Roosendaal, Licht op een Veranderde Stad, ISBN 978-94-90358-10-59, publ. Stichting Ghulden Roos 2015, p. 224.