Patent ID: 7970305

Claim:
A development apparatus that develops an electrostatic latent image formed on an image carrier, comprising: a developer roller operable to carry toner on a circumferential surface thereof and develop the electrostatic latent image using the toner; a supply roller operable to perform toner supply to the developer roller; a voltage applier operable to apply a bias voltage V 1 to the developer roller and apply a bias voltage V 2 to the supply roller; and a controller configured to control the voltage applier in an image formation mode so that a value obtained by subtracting an average S 2 of the bias voltage V 2 per unit time from an average S 1 of the bias voltage V 1 per unit time indicates a different polarity than a charging polarity of the toner when the toner is in a non-degraded state, and to control the voltage applier in a toner consumption mode so that a value obtained by subtracting the average S 2 of the bias voltage V 2 per unit time from the average S 1 of the bias voltage V 1 per unit time indicates a same polarity as the charging polarity of the toner when the toner is in the non-degraded state, the toner consumption mode performing development at a time of non-image formation being a time other than image formation based on a print job externally sent thereto to discharge the degraded toner accumulated in the development apparatus to the outside thereof.