Patent ID: 8224216
Filing Date: 2012-07-17
Classification: G03G

Abstract:
1. A developing apparatus comprising: a transport member comprising a plurality of electrodes forming a traveling wave electric field by successively applied voltages; and a casing storing a toner transported by the transport member, wherein the toner comprises electrostatically active polar groups that enable the toner to be transported through the action of an electric field without the need for precharging the toner, as characterized by an activity of the toner based on the following measuring method shown in (1) to (3) of not more than 2.0×10 (1) dipping the toner in an aqueous solution containing an excess equivalent of benzethonium chloride with respect to electrostatically active polar groups present on a surface of the toner to electrostatically react the polar groups and the benzethonium chloride with each other; (2) adding sodium lauryl sulfate dropwise to the aqueous solution to react the same with the residual benzethonium chloride, thereby measuring a quantity of the sodium lauryl sulfate reacting with the residual benzethonium chloride; and (3) calculating the activity on the surface of the toner from the quantity of the reacting sodium lauryl sulfate.