Patent ID: 7729631

Claim:
An image forming apparatus comprising: a main body; a developer accommodating unit that is configured to accommodate developer and that is detachably mounted in the main body; an image forming unit that forms an image on a surface of a recording medium with the developer; a mode setting portion that sets a mode to either one of: a normal mode in which a developer amount set value T is set to a base developer amount Tbase, the developer amount set value T being an amount of developer consumed for forming an image on a single sheet of the recording medium; and a developer-saving mode in which the developer amount set value T is set to a value smaller than the base developer amount Tbase based on a saving coefficient S, the saving coefficient S being greater than zero and smaller than one; a parameter obtaining portion that obtains both a cumulative number of printed sheets Pttl that is a cumulative number of sheets of the recording medium on which an image is formed since the developer accommodating unit is mounted in the main body, and a developer remaining amount Rt that is an amount of developer remaining in the developer accommodating unit; a determining portion that determines in the developer-saving mode whether a first inequality Rt≦T base× Sdef ×( P max− Pttl ) is satisfied, where a default saving coefficient Sdef is a default value of the saving coefficient S, and a maximum number of printable sheets Pmax is a maximum number of printable sheets that is preset for the developer accommodating unit; and a saving-coefficient setting portion that sets the saving coefficient S to the default saving coefficient Sdef if the determining portion determines that the first inequality is satisfied, and that sets the saving coefficient S to a value satisfying a second inequality Sdef<S≦Rt/{T base×( P max− Pttl )} if the determining portion determines that the first inequality is not satisfied.