Patent ID: 9304432
Filing Date: 2016-04-05
CPC Classification: G03G

Claim Text:
1. An image forming apparatus, comprising: an image carrier on a surface of which an electrostatic latent image is to be formed and a toner image is to be carried; a developing device which includes a development housing configured to store developer containing toner to be charged to a predetermined polarity and carrier, a magnetic roller configured to receive the developer in the development housing and carry a developer layer by being rotated and a developing roller configured to receive the toner from the developer layer, carry a toner layer and supply the toner to the image carrier by being rotated in a state held in contact with the developer layer; a bias applying unit which applies development biases, in which an alternating current voltage is superimposed on a direct current voltage, to the magnetic roller and the developing roller; a leak detecting unit which detects a leak generated between the image carrier and the developing roller or a leak generated between the developing roller and the magnetic roller; a bias controller which controls the bias applying unit to provide a potential difference between the magnetic roller and the developing roller so that the toner moves from the magnetic roller to the developing roller during a developing operation in which the toner is supplied from the developing roller to the image carrier; and a leak detection controller which performs a leak detecting operation for detecting the value of an inter-peak voltage of the alternating current voltage of the development bias applied to the developing roller, at which the leak is generated, while changing the inter-peak voltage at a time different from that during the developing operation; wherein the leak detection controller: successively performs a plurality of the leak detecting operations at predetermined timings; increases the inter-peak voltage from a preset reference detection starting voltage and detects the inter-peak voltage when the leak is detected as a leak generating voltage in the first one of the plurality of leak detecting operations; and increases the inter-peak voltage from a first detection starting voltage calculated according to the already detected leak generating voltage and higher than the reference detection starting voltage and detects the inter-peak voltage when the leak is detected as the next leak generating voltage in the second or subsequent leak detecting operation.