Patent ID: 9229399
Filing Date: 2016-01-05
CPC Classification: G03G

Claim Text:
1. An image forming apparatus, comprising: multiple image forming units each including a latent image bearer and a developing device to develop a latent image on a surface of the latent image bearer with toner; a transfer device to transfer toner images on the multiple latent image bearers either onto a recording sheet after transferring the toner images from the multiple latent image bearers onto a surface of an endless rotary member or directly onto a recording sheet held on a surface of an endless rotary member; a cleaner to clean the surface of the endless rotary member by removing transfer residual toner adhering thereto after a transfer process; and a controller to execute a forcible toner consumption process to forcibly consume degraded toner stored in one or more developing devices of the multiple image forming units by forming a toner image for forced consumption in a non-image region of the latent image bearer with an amount of toner corresponding to a difference between an image area ratio of a developed image and a prescribed threshold thereof when the image area ratio of the developed image is lower than the prescribed threshold, wherein, in the forcible toner consumption process, the controller calculates a total consumption required amount of toner by adding together amounts of consumption required toner in the respective image forming units each calculated in accordance with the image area ratio of the developed image in each of the multiple image forming units, wherein the controller determines an amount of toner actually used to form a toner image for forced consumption in at least one of the multiple image forming units so that the total amount of actually used toner in the respective image forming units becomes less than a prescribed total maximum amount, determined in accordance with cleaning performance of the cleaner, when the total consumption required amount of toner exceeds the prescribed total maximum amount, wherein the controller reflects a difference between the amount of toner determined to actually adhere to the toner image for forced consumption to enable the total amount of actually used toner in the respective image forming units to be less than the prescribed total maximum amount and the consumption required amount of toner calculated in accordance with the image area ratio of the developed image in at least one of the multiple image forming units to a consumption required amount of toner to be calculated in the next forcible toner consumption process in at least one of the multiple image forming units, wherein the toner images formed for forced consumption by the respective image forming units are transferred to and superimposed on the endless rotary member.