Ion charging development system to deliver toner with low adhesion

Interdigitated electrodes on a donor roll enable uncharged toner to be picked up from a fluidized bed reservoir. This layer of toner is subsequently charged by exposure to a corona device and delivered to a development zone, where it is used to develop an electrostatic latent image. Residual toner on the donor is neutralized by exposure to a second corona device and then stripped for return to the fluidized bed by applying an AC voltage between adjacent donor electrodes. So-called ion charging of the toner is known to cause the particles to have low adhesion, allowing development with DC fields alone. Optionally, an AC voltage can also be applied to adjacent donor electrodes in the development zone to enhance particle release. In addition to providing a means to impart adequate flow to the toner in this single component development system, the fluidized bed reservoir, in conjunction with ion charging, also provides a means for blending dry powder toners to achieve custom color development.