It is clarified by the experimental procedure and theoretical models that there exist two types in toner concentration dependence of toner charge at two-component developer. One is independent (
Yasusuke Takahashi, Teruki Kishimoto, Won-Sup Lee, "The Physics of Toner Concentration Dependence of Toner Charge at Two Component Developer" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP16), 2000, pp 603 - 607, https://doi.org/10.2352/ISSN.2169-4451.2000.16.1.art00046_2