Special deluxe lamps

Tricolor lamps show only emission in restricted wavelength intervals. For objects with a reflection spectrum peaking outside these regions the color appearance under illumination with a tricolor lamp will differ from the one under illumination with a black body radiator. Although a CRI of 83 quarantees a normal appearance for most objects, some typical colors will look unnatural under illumination with a tricolor lamp. For certain applications, therefore, a higher CRI is required. Examples of such applications are museum illumination and flower displays. For this purpose special deluxe lamp>s were developed with a CRI of 95. Simultaneously we have to accept an efficacy drop to 65 Im/W [3],... 

Fig. 6.16. Emission spectrum of a Special Deluxe lamp with a color temperature of 4000 K. Reproduced with permission from Ref. [3]...

The phosphors in the tricolor lamp show another advantage over the halophosphate phosphors, viz. a much better maintenance during lamp life. In Fig. 6.IS the output decrease after 2(KX) hours of burning is plotted as a function of the wall load. The higher stability of the rare-earth activated phosphors is translated into a higher maintenance. The value of the wall load is determined by the tube diameter (see Fig. 6.18). Tricolor and Special Deluxe lamps are now available in a tube diameter of 25 mm, to be compared with the 36 mm of the halophosphate tube. It even proved to be possible to reduce the tube diameter to 10 mm. With this small diameter the discharge tube can be fold up and the compact luminescent lamp is bom. 

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