Integrated process capability analysis with an application in backlight module

Backlight application specializes in supplying light, with notable examples including liquid crystal display (LCD), hand-phone LCD, and PDA LCD. The integrated process capability and integrated process yield for cold cathode fluorescent lamp backlight are unknown. Process capability analysis is a highly effective means of assessing the process ability of backlight that meets specifications. A larger process capability index (PCI) implies a higher process yield, and lower expected process loss. Chen et al. [Int. J. Product. Res. 39 (2001) 4077], applied indices C-pu, C-pl, and C-pk to evaluate the integrated process capability for a multi-process product with smaller-the-better, larger-the-better, and nominal-the-best specifications, respectively. However, Cpk suffers from the weakness of being unable to reflect the specific process yield. This study selects index C-ps, to replace C-pk. Meanwhile an integrated PCI for the entire backlight module is proposed, and the relationship between the PCI and process yield is described. A multi-process capability analysis chart, which reasonably accurately indicates the status of process capability for the backlight module, is designed for practical applications. (C) 2002 Elsevier Science Ltd. All rights reserved.