The Halogen G9 Bulb

G9 Halogen Lamps
These state of the art, high precision bulbs are often the first choice for accent lighting. They are extremely popular with architects, lighting designers, and domestic consumers alike, often featuring in desk lighting and in illuminating display cabinets. They are a far more energy efficient light bulb than traditional incandescent bulbs, lasting for thousands upon thousands of hours. These days they are available in a wide range of wattage and with clear or frosted finishes. Research and development is always improving their design year on year, keeping them at the forefront of lighting technology. This article explains the evolution of the technology from early floodlights, to the stylish accent and desk lighting favoured by designers worldwide today

The 1950s - 1960s: Specialist Halogen Bulbs 
The General Electric Company (GEC) pioneered the earliest versions of tungsten halogen lamps back in the late 1950s and early 1960s in Wembley, London (UK). Previously tungsten lamps blackened with time, as tungsten atoms began to collect on their capsules. Adding halogen gas not only stopped the blackening process, it allowed for more compact designs and a much longer lifespan. The first types ever produced featured a linear quartz tube of glass moulded to a ‘pinched’ closing at both ends, and inside was an axial filament. They were fantastic for use in flood lights projecting a good amount of bright light over a larger area. In the meantime incandescent bulbs still held more allure in everyday use, where a more concentrated diffusion of light was needed. Mass production was also somewhat hampered by the need for two ‘glass to metal seals’ resulting in higher costs in the manufacturing process. 1961 brought a breakthrough as GEC researcher J.A. Moore created the world’s first single ended low voltage halogen lamp. Featuring only one metal seal, it simplified production and also introduced a much lower voltage filament in a much smaller capsule. Early uses included slide projection with the A1/215 (FCR) 24 volt 250 watt capsule. There were also various applications within photography and 8mm cine projection around this time. In the UK, the General Electric Company developed their use within airfield and automotive lighting applications. 

The 1970s – 1980s: Halogen Bulbs Move Into Wider Applications 
The overall concept was further developed for mass marketing within Europe by Thorn Lighting. They were looking to expand on their range of accent lighting and options for display lights. Researcher Alex Halberstadt created a 12 volt 250 watt capsule at Thorn’s Enfield laboratories that also used a single ended capsule concept. Far more effective than their previous incandescent offerings, the new low voltage halogen bulb offered a stylish yet long-lasting alternative. The concept spread from London’s Enfield laboratories to become a worldwide standard for its field, all using low voltage transformers. 

The 1990s Onwards –High Voltage Single Ended Halogen Capsules Change The Game 
In 1999 German company Osram created a type of mains voltage halogen bulb which effectively ended the reliance on low voltage transformers. This crucial innovation paved the way for the G9 Halogen lamp bulbs. It allowed for far more versions to become commercially available below 75 watts. Secondly it eliminated the need for enclosed fixtures previously needed due to the risk of explosion at the end of the products lifespan.  Instead the lamp was filled at a far lower gas pressure and featured an additional safety feature never seen before. A special fuse shut down the lamp’s operation altogether in the event of arcing as a result of filament failure. 

The problem was that arcing involves the transmission of a high enough current to allow the thin foils within the seal to rapidly heat, sometimes shattering the quartz close to weld points. The answer lay in cutting out the quartz bridge arrangement altogether. Traditionally wires supporting the filaments lead to the bridge, and were welded to molybdenum foils. The problem was they were of such a large diameter that arcing presented a real problem – they simply could not withstand the current for sufficient quantities of time. Osram took the concept and turned it on its head. Their ‘no bridge’ version supported its filaments using small custom dimples set instead within the bulb itself. Filament tails then went directly through the pinch to weld straight onto the foils – for a very good reason. The tails themselves would rapidly evaporate in the event of arcing, reliably acting as built in fuses that broke the circuit within 0.7 milliseconds. 

Another game-changing innovation was the Sylvania E550 halogen lamps in 1996 which offered an alternative to PAR and R lamps. Offering greater sparkle from flat optical surfaces, the secret lay in again eliminating the need for a low voltage transformer (as had been previously required for display lamps such as the earlier MR16). Using the mains supply opened up a much wider scope of applications, including domestic and semi-professional uses:  desk lighting and display rapidly became a much more interesting concept for designers. This lamp featured a then unique W-shaped filament with a 25mm length 230-240 volt coil within a tiny halogen capsule focussed in a 50mm reflector. Aluminosilicate glass replaced the traditional quartz, improving safety by allowing for glass to metal seals to incorporate molybdenum wires. As mentioned earlier, previously casings could occasionally explode at the end of their lifespan. Now, five support wires passed through the seal to accommodate the W-shaped filament. At the same time, GEC invented the revolutionary GU10 halogen bulbs base, which replaced the fragile 12v dual pin system with a positive lock and twist action. The combination lead the E550 to become a true market leader. It is true it initially lost some ground on energy efficiency: early GU10 capsules could only produce some 10.5lm/w, compared to the 290lm/W generated by a 12 volt 50 watt MR16. Beam control was also an issue, with a 230 volt lamp only able to produce something like a third of the intensity of a comparable beam angle 12volt lamp.  

Today’s Modern Accent, Display & Desk Lighting Choices
With the development of G9 Halogen Lamps the process has moved on even further. These modern bulbs use mains supplied fittings, with loops or pins, producing a high lumen output from extremely compact designs. There are available in a variety of energy saving specifications. Representing a very long lasting bulb, they are one of the most popular choices for accent lighting used worldwide in commercial and domestic settings today.