Velleman Compact fluorescentlamps(CFL) - Manual (Page 3)

Spectrum of light
The light of CFLs is emitted by a mix of phosphors on the inside of the tube, each emitting a different
colour. Modern phosphor designs are a compromise between the shade of the emitted light, energy
efficiency and cost.
Colour temperature is mostly indicated in Kelvin
Color temperature kelvin
'Warm white' or 'Soft white' ≤ 3000 K
'White' or 'Bright White'
3500 K
'Cool white' 4000 K
'Daylight' ≥ 5000 K
Colour temperature is a quantitative measure. The higher the number in Kelvin the 'cooler' (bluer)
the shade will be.
CFLs are also produced in other colours:
• Red, green, orange, blue, and pink, primarily for novelty purposes
• Blue for phototherapy
• Yellow, for outdoor lighting, because it does not attract insects
• Black light (UV light) for special effects
Design and application issues
A spiral‐type integrated compact fluorescent lamp, with combined tube and electronic ballast. This
style has slightly reduced efficiency compared to tubular fluorescent lamps, due to the excessively
thick layer of phosphor on the lower side of the twist. Despite this, it has become one of the most
popular types among consumers since its introduction in the mid 1990’s.
The primary objectives of CFL design are high electrical efficiency and durability. However, there are
some other areas of CFL design and operation that are problematic: