Philips Mixed Light ML 160W for Automatic Assembly

This special lamp has been made in a clear bulb to reveal the latest internal construction of the Philips Mixed Light 'ML' lamps. It was developed to address cost pressures affecting mercury-blended lamps as they reached commercial maturity, when significant sales volumes still remained but with low selling prices that challenged profitability.

Although all mercury lamps came under cost pressures as they neared obsolescence, self-ballasted types were severely affected because of the high degree of manual labour in their assembly. Whereas most manufacturers relocated production to low-wage countries, Philips redesigned its lamps to greatly reduce the labour cost element. Production was thereby retained a for few years longer in Europe.

The heart of new design centres around an automatic filament mounting mechanism, based on a glass bridge support similar to the type found in PAR38 incandescent reflector lamps. A high speed machine melts two sturdy wires into the ends of a glass rod, and five fine molybdenum support wires follow. This is welded in a single operation to the arc tube, resistor, getter pan and glass support stem, followed by automatic mounting of the filament. Previously a secondary getter was applied to the filament, but in this design a spot of red phosphorous is applied directly to the arc tube surface. That proved to be a notable drawback, because it was difficult to correctly control the getter quantity. Frequently far too much was applied, and the bulbs acquired a strong ginger colouration that reduced light output. Some customers were also troubled by the fact that the filament and arc tube centres were no longer aligned, compared to the earlier ML construction.
Manufacturer: Philips Lighting
Lamp Power: 160 Watts
Lamp Current: 0.67 Amps
Lamp Voltage: 235-245 Volts
Cap: B22d/25x26
Bulb Finish: Clear
Bulb Type: E-70 Soda-lime
Overall Length: 165 mm
Light Centre Length:
Electrodes: Coiled-Coil backwound Double carbonate emitter
Inner / Outer Atmosphere: Inner: Ar | Hg Outer: Nitrogen
Luminous Flux: 3,000 lm (at 100 hours)
Luminous Efficacy: 18.8 lm/W (at 100 hours)
Colour Temperature & CRI: CCT: 3800K CRI: Ra 60
Chromaticity Co-ordinates: CCx: 0.349 CCy: 0.380
Burning Position: Horizontal
Rated Life: 6,000 hours (to 50% survival)
Warm Up / Re-strike Time: 4 minutes 10 minutes max.
Factory: Weert, The Netherlands
Date of Manufacture: July 2003
Original / Present Value: No commercial value
References: 1) Private communication, Jan ten Haaf, Philips Lighting Weert 2003.