Bulbs And Ballasts
PAST • PRESENT • FUTURE
PRE 1970’s - OLD TECHNOLOGY • LAST CENTURY
Incandescent bulb makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated low luminous efficiency.
1980’s - PRESENT TECHNOLOGY
Halogen, is an incandescent bulb with a tungsten filament contained within an inert gas and a small amount of a halogen such as iodine or bromide. The combination of the halogen gas and the tungsten filament produces a chemical reaction known as a halogen cycle which increases the lifetime of the filament and prevents darkening of the bulb by redepositing tungsten from the inside of the bulb back onto the filament. Because of this, a halogen bulb can be operated at a higher temperature than a standard gas-filled lamp of similar power and operating life. The higher operating temperature results in light of a higher colour temperature This, in turn, gives it a higher efficiency. Due to their smaller size, halogen is more efficient in how they create light.
THE FUTURE - BRIGHTER • WHITER • LIGHTER
HID (high-intensity discharge) lamp is a type of electrical bulb which produces light by means of an electric arc between tungsten electrodes housed inside a translucent arc tube. This tube is filled with both gas and metal salts. The gas facilitates the arc’s initial strike via a high voltage pulse produced by the igniter. Once the arc is started, the ballast maintains a constant arc which evaporates the metal salts forming a plasma, which greatly increases the intensity of light produced by the arc and reduces its power consumption.
Compared with incandescent bulbs, HID lamps have higher luminous efficiency since a greater proportion of their radiation is in visible light as opposed to heat. Their overall luminous efficiency is also much higher: they give a greater amount of light output per watt of electricity input.
HID ... THE FUTURE OF LIGHTING