Patent ID: 8335445

Claim:
A development apparatus, comprising: a first toner carrier configured to be disposed facing a rotating image carrier and to develop an electrostatic latent image formed on the image carrier; a second toner carrier configured to be disposed, facing the image carrier, on a downstream side of a rotating direction of the image carrier, and to develop the electrostatic latent image; a developer carrier for carrying developer containing toner and carrier and for supplying the toner to the first toner carrier and the second toner carrier; and a power supply for supplying during a total duration of developing: 1) a first voltage containing a first alternating current component to the first toner carrier, 2) a second voltage containing a second alternating current component to the second toner carrier, and 3) a developer carrier bias voltage containing a third alternating current component to the developer carrier, wherein the total duration of developing comprises a first duration and a second duration and wherein a first fraction defined as a ratio of the first duration to the total duration of developing has a value that is not equal to a second fraction defined as a ratio of the second duration to the total duration of developing: wherein during the first duration the first voltage is higher than or equal to an average value thereof and the developer carrier bias voltage is lower than or equal to an average thereof, or the first voltage is lower than or equal to the average thereof and the developer carrier bias voltage is higher than or equal to the average thereof; and wherein during the second duration the second voltage is higher than or equal to an average value thereof and the developer carrier bias voltage is lower than or equal to the average thereof, or the second voltage is lower than or equal to the average thereof and the developer carrier bias voltage is higher than or equal to the average thereof.