||America's first energy-saving halogen replacement for the ordinary A-line incandescent lamp made its debut in 1987, with the launch of this product from General Electric. It was positioned as a high performance lamp delivering the same luminous flux as a 60W incandescent lamp but for a power consumption of just 51W, and with the lifetime being doubled from 1000h to 2000h. It was joined by a similar model rated 90W and also having 2000h life, intended to replace the ordinary 100W 750-hour incandescent.
At the heart of the lamp is a small single ended tungsten halogen capsule which contains an unsupported coiled-coil axial filament. In common with other American halogen lamps, the capsule is fabricated in aluminosilicate hardglass instead of the internationally-preferred quartz. This choice of capsule material brings to a minimum the increase in cost vs inacandescent lamps since hardglass is a cheaper material, and the production machinery can also run at much higher speeds and with greater efficiency than for quartz.
Hardglass capsules do however have an elevated risk of shattering at end of lamp life. To avoid risk of damage or injury, the outer bulb is blown in heavy-wall glass designed to withstand the force of a capsule explosion. It is also coated externally with a protective Teflon coating, designed to hold the fragments together in case it should be broken. The bulb is acid-etched on its inner surface to provide a diffusing effect. The capsule is ingeniously welded to a metal support frame which engages in grooves moulded into the bulb neck, and the ends of this frame are firmly clamped in place by screwing the brass cap over the threaded end of the glass bulb, without need for cement.