After the use of standard light bulbs with incandescent tungsten filaments
was banned, the development of light sources took three different directions
– the use of halogen light bulbs sealed in standard casing, the replacement
of light bulbs with compact flourescent tubes, and the substitution of
light bulbs for discrete performance light emitting diodes (LEDs). Each
of these alternatives had a number of disadvantages in comparison with
classic light bulbs. The only advantage was higher efficiency. (Halogen
– relativly low efficiency – (class D), short lifespan. Compact fluorescent
tubes – light builds slowly, bad start in low temperatures, flickering,
unsightly shape, bulky ballasts, mercury content, lifespan. Discrete LED
– directionality, unsightly form due to cooling).
The majority of these drawbacks are now being eliminated by new LED filament
technology, rods assembled from a series of small LEDs and equipped with
a luminophore layer. One rod has a luminosity of around 100 lm/W. The rods
are inserted into classic bulbs in a similar way to tungsten filaments
in original light bulbs. These light bulbs radiate in all directions, do
not require coolers, and their luminous efficacy corresponds to class A+.
The lifespan of such bulbs exceeds 40,000 hours and switching frequency
is not limited. They can function in a wide range of temperatures from
-25 to +45°C and power supply ranges from 110 ÷ 240 V/50Hz. They are produced
in colour designs from warm white 2700°K to day white light 6000°K.