In electrophotographic process, the system to transfer several times is used for the color image formation. The phenomenon that toner images has formed already on the recording medium returns to photoconductive drum was confirmed, and it is clear that this phenomenon is found conspicuously on the photoconductive drum where the toner does not exist. The electrification charge inside of toner image on recording medium is uneven, and this is thought so that an electric field formed at the toner transfer end point works to the direction that seems to return one part of toner on recording medium to photoconductive drum. In this work we theoretically analyze the electrification voltage inside of toner image at the end point of toner transfer, it is clear the reason why toner return to photoconductive.
Yoshie Iwakura, Hirokazu Fujita, "Solution for the Retransfer Mechanism of Color Imaging Process" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP14), 1998, pp 432 - 435, https://doi.org/10.2352/ISSN.2169-4451.1998.14.1.art00025_2