Fixer or ink detection in hardcopy apparatus

摘要

To check that nozzles of printheads 11-15 applying fixer or an ink to a print media 22 are operating correctly, the fixer or ink is applied to selected locations on a fluorescent print media which is then subjected to ultra-violet radiation; the reflectivities at these locations are detected in the visible spectrum and the information is analyzed using appropriate image processing algorithms. In an ink-jet printer, for example, applied fixer may be irradiated with ultra-violet light by a source 30 and applied inks may be irradiated with visible light, with a common detector in the visible light range being employed.