Patent ID: 8355657

Claim:
A development unit for a latent image carrier, comprising: a toner carrying device facing the latent image carrier and configured to have a first electrode and a second electrode arrayed with a given interval, said first electrode and second electrode comprising respective circumferential electrodes extending along an edge circumference of the toner carrying device with each of the edge circumferential electrodes having at least one section extending longitudinally along an outer region of the toner carrying device, the first electrode and the second electrode each being supplied with a given voltage to set an electric field changing in a given time cycle between the first electrode and the second electrode, the electric field being used to hop toner particles on or over the toner carrying device to form a toner cloud for developing a latent image formed on the latent image carrier; a regulating member configured to regulate an amount of toner on the toner carrying device; and a toner leak protection member made from a conductive material and configured to prevent leakage of toner particles from the development unit, the toner leak protection member being disposed at a downstream side of the regulating member with respect to a direction of surface movement of the toner carrying device, the toner leak protection member being supplied with a bias voltage, wherein the bias voltage comprises a voltage value being set to a same potential as an average potential of the given voltage supplied to any one of the first electrode and the second electrode.