This study analyzes idle time effect on a color electrophotographic (EP) printer. The idle time effect is defined as color or tone variations between the prints before- and immediately after- a printer having been idle for an extended period of time. In the study, 15 hours of idle time, which is regularly experienced in an office setting from 5pm to 8am, is investigated. Four off-the-shelf printers of the same model were placed in a temperature controlled environment with their engine calibration disabled. First, a preliminary experiment to know the inherent printer characteristics was conducted. With the preliminary experiments, the design of the experiments for the idle time effects was determined and total 39 sets of experiments were performed. More than 75% of the cases showed statistically significant tone differences, which are greater than 2 ΔE76 from paper white, for test pages printed before and after the idle time. It is also shown that these tone variations diminished once three pages have been printed after the idle time ends.
Sangbok Lee, Yuehwern Yih, George T.-C. Chiu, Jan P. Allebach, "Analysis of Idle Time Effect on Color Consistency of Electrophotographic Printer" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP25), 2009, pp 690 - 693, https://doi.org/10.2352/ISSN.2169-4451.2009.25.1.art00078_2