Blue Pinch(tm) Technology overcomes the temperature limitations of current lighting technology. Because the lamps are more resistant to overheating, they can be made smaller. For location lighting, the compact Blue Pinch lamp can be transported in the boot of a car, lighting stands can be downsized and, because it is lightweight, rigging times are faster and involve fewer people.
Blue Pinch also offers solutions where practical or aesthetic demands make adequate ventilation difficult. For example, "Vari*Lite" incorporate the 1OOOW Blue Pinch lamp in their highly successful "VL5" moving light. To minimise the escape of light through ventilation holes, the fitting allows heat from the lamp to radiate back through a large diameter dichroic reflector. This then radiates through the black die-cast body of the back of the fitting. The Blue Pinch lamp survives where conventional types would overheat. Further, where the noise of a cooling fan would be intrusive, its use can often be dispensed with if a Blue Pinch lamp is designed in.
New Range
"Blue Pinch" is the name given by Philips Lighting to a new range of single ended studio and theatre lamps designed to operate at higher ambient temperatures than conventional types resulting in permissable pinch seal temperatures of 500ºC.
However, if existing lamps operate satisfactorily in current luminaires then what is the need for lamps to cope with higher temperatures, you ask?
Well, to appreciate their benefits, one needs to go back and have a look at the operation of Tungsten Halogen lamps and see the way in which they work and their limits of operation-
The Halogen Cycle
Tungsten Halogen lamps differ from their predecessors, hard glass lamps in that their bulbs are not made of glass but instead, from quartz. The main advantage of quartz is that because it has a very much higher melting point than glass, it can be operated at temperatures up 1000ºC by which time glass bulbs would have softened and melted. This allows the bulb to be much smaller than the earlier lamps but more important, helps the operation of the "Halogen cycle" in the newer Tungsten Halogen lamps.
The addition of 'halides' to the gas fill helps the lamp to last longer and prevents blackening on the inside of the bulb wall. In a conventional lamp, as the Tungsten evaporates from the coil, it condenses on the cooler outer bulb, and when the lamp is switched off, this is apparent as a dark shadow.
When the lamp is at it's running temperature, the halides combine with the evaporating tungsten forming a gas but because now we have a very small and hot quartz bulb, it's inside surface is too hot for the gas to condense, thus its components remain in combination. However when this gas comes close to the filament again, it dissociates back into tungsten and halogen and the tungsten is redeposited on the coil. This accounts for the slightly crystalline structure of a coil after it has burnt for some hours, resulting from the redeposition of tungsten.
The ensuing benefits of this cycle are that the lamp will last longer than a conventional lamp, it does not blacken and in addition maintains its colour temperature. If a coil thins over life, then it will change colour temperature; not a major problem for the theatre but unacceptable for television and film applications which need stable colour temperature for optimum colour balance.
Pinch seals in Quartz lamps
So far so good, but one problem with quartz is that because it's coefficient of expansion is virtually negligible, it is difficult to seal the lead out wires necessary for the power to be delivered to the coil.
Conventional lamps have composite lead out wires made to have exactly the same coefficient of expansion as glass but quartz lamps use very thin molybdenum foils which lead out through the "pinched" section of the lamp at the base. Within the lamp, the tungsten supports are welded to the foil and outside the bulb, short wires are connected to the lamp pins-
Versatile as the molybdenum foil is, its limitation is that its maximum safe operating temperature is between 350-400ºC, above which temperature, it starts to oxidise.
It is inevitable that a small amount of air will be present adjacent to the foil / lead out wire junction, within the lamp pinch and if it's temperature exceeds 350ºC, then it will slowly oxidise This oxide being of a higher volume than the foil, as is rust on steel, will cause the quartz pinch to be fractionally forced apart thereby allowing the further ingress of air. The oxidisation process then continues and over a relatively short period of time, the lamp can fail when air finally enters the bulb-
The limiting pinch temperature for 800 hour theatre lamps is 350ºC but for 3200ºK studio lamps of only 200 hour rated life, it is 400ºC.
The advent of 'Blue Pinch Lamps'
These limiting temperatures have been the norm for the last 15 or more years until the recent introduction of 'Blue-Pinch Technology'. The Blue Pinch treatment of the molybdenum foil allows it to operate at 500ºC, so it offers the opportunity for making lamps more resistant to over-heating so they can be smaller.
Generally the dimensions of any lamp including it's 'Light Centre Length' ( LCL) are determined by how short it can be made without overheating the seal. Now that the seal temperature can get as hot as 500ºC, the distance from the pinch-seal to the filament can be reduced without exceeding this limit.
The benefits of Blue Pinch
This then has the advantage that luminaires can be made smaller and be fitted with a smaller diameter fresnel lens and overall can be reduced in size. For location lighting, this is a tremendous advantage, since smaller lighter fittings can be transported more easily, perhaps in the boot of a car instead of a small van, lighting stands can be downsized and because of the reduction in weight, rigging time can be faster or with fewer people.
Further advantages are realised in the design of luminaires where for practical or aesthetic reasons, adequate ventilation may be difficult to achieve without the use of fans. For example, 'Vari*lite' incorporate the 1000W Blue Pinch lamp in their highly successful 'VL5' moving light- To minimise the escape of light through any ventilation holes, the fitting relies on allowing heat Iron the lamp to radiate back through a large diameter dichroic reflector and this then radiates through the black diecast body of the back of the fitting. Conventional lamps would overheat but the Blue Pinch version survives!
Further, where the noise of a cooling fan would be intrusive, in for example a "follow spot" within an auditorium, the fan can often be dispensed with if a Blue Pinch lamp is designed in.
Manufacturers using Blue Pinch
Luminaires are now available with blue-pinch lamps from Desisti, Strand and Sachtler for the film lighting market and are in development from Niethammer and Imax for projection effects.
Blue-pinch luminaires are currently in development by the European manufacturers, Coemar and Amptown, in New Zealand by Selecon and in Japan by Matusamura and Maruma.
The Range
The current range of lamps from Philips in Blue Pinch is
Wattage Voltage Cap/base Light Centre Length
1000w 23Ov GY 9-5 46,5mm
1000w 240v GY 9-5 46,5mm
2000w 230v G22 63,5mm
2000w 240v G22 63,5mm
5000w 230v G38 127mm
5000w 240v G38 127mm