Abstract

The detection of topographic defects in automobile paint finish is dependent on the modulation (contrast) of the specular highlights reflected from defects, against their immediate background: the angular size of the specular highlights reflected from defects and the percentage of the vehicle surface over which the modulation and the angular size of the specular highlights associated with the defects are above threshold levels.

Two lighting variables of relevance to the facility designer, lamp width and spacing, are known to have an effect on defect modulation and the area of the specular highlights on defects. Two laboratory evaluations were conducted in which paint inspection performance was measured as a function of 33 combinations of lamp width and spacing. From these results response surfaces were fit to the data. The resulting surfaces show that performance is maximized when lamp width is in the approximate range of 25 to 60 mm and spacing is in the approximate range of 120 to 220 mm. Ratings of comfort and distraction are maximized when lamp width is in the approximate range of 30 to 80 mm and spacing is in the approximate range of 170 to 400 mm.