Patent ID: 8007064

Claim:
An image forming apparatus, comprising: a plurality of ink cartridges to contain ink, each ink cartridge including a memory on which information is writable or updatable; a plurality of image forming units to form images using the ink contained in the corresponding ink cartridges; an ink-remaining-amount manager to manage an amount of ink remaining in each of the plurality of image forming units; a maintenance determiner to determine at least one of a need for and a type of maintenance to be executed on each of the image forming units; an information writer to write or update, when an ink near-empty or empty state occurs in a first one of the ink cartridges, information indicative of a spent state on the memory of the first ink cartridge; an ink-amount estimator to estimate an amount of ink required to execute the maintenance on each of the ink cartridges; and a maintenance executability determiner to determine executability of the maintenance on each of the ink cartridges by comparing the remaining ink amount obtained from the ink-remaining-amount manager and the required ink amount obtained from the ink-amount estimator, wherein, if the ink near-empty or empty state of the first ink cartridge is caused by image formation, the ink-amount estimator estimates an amount of ink required to execute the maintenance on each of the other ink cartridges based on the at least one of the need for and the type of maintenance determined by the maintenance determiner to be executed on each of the plurality of image forming units, and wherein, if the maintenance executability determiner determines that the maintenance is not executable on at least one of the other ink cartridges based on the required ink amount and the remaining ink amount, the maintenance executability determiner determines that the at least one ink cartridge is at an ink near-empty or empty state and stops writing or updating the information indicative of the spent state on the memory of the at least one ink cartridge.