||This special lamp has been made in clear bulb to reveal the most recent re-design of the ML Mixed Light lamps from Philips. This type of lamp is nearing the end of its commercial lifetime, and although significant sales volumes remain, the average selling price has fallen to levels which make it very tough to profitably compete in the market.
It is especially hard to compete in view of the complex structure employed in mercury-blended lamps, and although all of the components are low-cost items, they were previously assembled with manual labour. To continue producing the lamp it was therefore necessary to transfer production to a low wage country, or redesign the lamp for completely mechanised production with the minimum requirement for human labour. This was the option chosen by Philips, and the knock-on impact in production price has enabled production to be maintained in the Netherlands.
The heart of the re-design centres around a new filament mounting mechanism, based on a glass bridge support similar to the type found in high power quartz halogen lamps. On high speed automatic equipment two sturdy support wires are pushed into either end of this bridge, and five fine molybdenum support wires follow. The filament is automatically loaded and the whole assembly, plus an arc tube, resistor and getter, are simultaneously brought together and welded to the stem. A new gettering technique has been employed in this lamp, in which a spot of red phosphorous is applied directly to the arc tube, instead of the filament. However it is not so easy to control the volume of getter applied this way. Frequently far too much is used, and the bulbs acquire a strong ginger colouration.