The average toner charge-to-mass ratio (q/m) is an important metric for two-component xerographic developers since xerographic development of solid and line or dot images is normally a simple inverse function of q/m. However, q/m is a distributed function, and for
other nonimage processes such as background development and machine dirt generation, the “tails” of the charge distribution are more important than the average q/m value. Thus, a detailed assessment of any particular xerographic developer should involve the measurement and
analysis of the entire charge spectrum. This viewpoint will be illustrated in the present paper by a comparison of simultaneous average q/m data (from a total-blow-off procedure) and distributed charge/size (q/d) data (from a charge spectrum). In particular, the direct connection
between these two types of charge measurements will be highlighted, both for normal charging processes and for admix processes that involve the addition of uncharged toner to a charged developer. Additionally, both positive and negative charging processes will be considered, with a common
set of test toners being driven to both polarities via specific carrier coatings.