US Patent 7665821 Inkjet printer and maintenance method thereof

In an inkjet printer according to an aspect, a print head includes a nozzle and ejects ink through the nozzle. A maintenance unit performs a maintenance operation to recover an ejection state of the nozzle. A sealing unit selectively exposes and seals the nozzle. A first timer unit measures a sealing time when the sealing unit seals the nozzle. A second timer unit measures an exposing time when the sealing unit exposes the nozzle. A dryness obtaining unit obtains a dryness level of the nozzle based on the sealing time and the exposing time. A limit level storing unit stores a predetermined dryness level as a limit level. A control unit activates the maintenance unit when the obtained dryness level is equal to or above the limit level.