The most common toner yield measure for electrophotographic printing devices is the number of letter-sized pages that can be printed with a toner cartridge based on average image coverage of 5%. Average toner cartridge yield methodologies are codified in standards ISO/IEC 19752 and ISO/IEC 19798∶2006 in accordance with a broad range of factors, including print job size, print quality mode, cartridge end-of-life determination, sample size and environmental conditions. The methodologies and results laid out in these standards are moreover based on average conditions which could be significantly different from the prevailing parameters of a specific job, the most significant of which are image coverage and the substrate being imaged. The need for a more exacting method of quantifying toner yields, which takes specific production parameters into account, is further underscored by the fact that toner costs in relation to the overall cost of a printed product are considerably higher than ink is in relation to the overall printing cost in conventional printing processes. In this research toner yield were determined as a function of the weight of toner consumed relative to the actual image coverage of four-color process images printed on synthetic paper by a Xerox DocuColor 7000 digital press. Total image area coverage for all colors was calculated from a PDF file using a Ghostscript interpreter and image coverage software. The calculated yield predictions per toner cartridge were 33% higher than the manufacturer's yield projections, which demonstrates that toner yields can deviate significantly from the manufacturer's specification, which are based on average rather than specific job parameters.
展开▼
