DL2482 datasheet(25/82 Pages) OSRAM

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2. Lamp data

Economical long-life light sources with plug-in bases.

Compact Fluorescent Lamps OSRAM DULUX®

Technical Guide

2.3.5 Factors affecting

colour consistency

There are a number of factors that affect colour consistency and the perception of the

light colour of compact fluorescent lamps.

Iridescence

Iridescence is a property of some anodised reflector finishes which results in a „rain-

bow“ effect when use in conjunction with trichrome phosphors. Since all OSRAM

DULUX® lamps contain trichrome phosphors, this effect caused by the reflector may

be wrongly ascribed to the lamps as „different light colours“.

Ambient temperature

The light colour of trichrome phosphors changes slightly as the ambient temperature

changes because of the relationship between luminous flux and temperature. This is

apparent in applications in which, say, open ceiling luminaires are installed close to

air-condition outlets. In such cases, the light colour may be slightly different from that

of luminaires located further away. This effect can be minimised by coordinating the

air-conditioning system with the lighting system.

Manufacturing tolerances

There may be minimal differences in the light colours of lamps from different manufac-

turers. In applications in which colour consistency is a critical factor, all the lamps in a

particular zone should come from the same manufacturer and should all be replaced

together. If lamps are replaced individually there may be differences in light colour.

Dimming

When fluorescent lamps are dimmed there is a slight reduction in colour temperature.

The colour temperature of a fully dimmed OSRAM DULUX® L 36 W lamp, for example,

is around 150 K lower than that of an undimmed lamp. The colour difference appears

greater to the eye because of the considerable difference in luminance. Even greater

differences may occur temporarily if there is a sharp change in the dimmer setting (see

4.7 and 5.1.4).

Ageing

Generally speaking, there are no changes in colour temperature or shifts in chromati-

city coordinates in the course of a lamp’s service life. However, lamps do suffer a drop

in luminous flux as they age (see 2.4) and it is the resulting difference in luminance

between an old lamp and a new lamp that give the impression of a change in colour

temperature.

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