The relation between the spectral distribution and colour rendering quality of illuminants is discussed with particular reference to the spectral distribution differences which can be experienced with white fluorescent lamps.
Because of the subjective nature of colour appreciation, factors such as colour preferences and colour contrasts are of great importance in fluorescent lamp colour design.
The respective functions of chromaticity co-ordinates and spectral band measurements are indicated. The colour of a fluorescent lamp itself can be accurately specified by its C.I.E. co-ordinates, and tolerances of any desired magnitude can readily be fixed. For an adequate specification of the colour rendering quality, however, it is necessary that the spectral distribution be known.
Eight spectral-band and chromaticity co-ordinate data are given for the principal phosphors employed in fluorescent lamps. A brief survey of the colours of natural daylight and incandescent light is included.
Reasons are given favouring the design of fluorescent lamp colours for general lighting service on the purple side of the black body locus, as evidenced in the Warm White and Natural lamps.
Recent developments in the application of fluorescent lamps to colour matching include fluorescent lamps with approximately 6,500deg.K black body spectral distribution and mixtures of blue fluorescent and incandescent light.
