Patent ID: 9217950
Filing Date: 2015-12-22
Classification: G03G

Abstract:
1. A developing device, comprising: a development housing configured to store a developer containing toner to be charged to a predetermined polarity and carrier; a developer carrier configured to receive the developer in the development housing and carry a developer layer by being rotated; a toner carrier configured to receive the toner from the developer layer, carry a toner layer and supply the toner to an image carrier having an electrostatic latent image formed on a surface and carrying a toner image to be developed by the toner by being rotated in a state in contact with the developer layer; a bias applying unit including one transformer and configured to apply direct-current voltages and alternating-current voltages having the same frequency and phases opposite to each other to the developer carrier and the toner carrier; a leakage detecting unit configured to detect leakage occurring between the image carrier and the toner carrier or leakage occurring between the toner carrier and the developer carrier; a bias control unit configured to provide a predetermined potential difference of the direct-current voltage between the toner carrier and the developer carrier and apply the alternating-current voltages so that the toner is transferred from the developer carrier to the toner carrier by controlling the bias applying unit during a developing operation in which the toner is supplied from the toner carrier to the image carrier; and a leakage detection control unit configured to detect a value of an inter-peak voltage, at which the leakage occurs, by applying the same direct-current voltage to the toner carrier and the developer carrier and changing the inter-peak voltages in a state where a ratio of the inter-peak voltages of the alternating-current voltages applied to the toner carrier and the developer carrier is kept constant during a leakage detecting operation different from the developing operation.