Patent ID: 7394998

Claim:
An image forming apparatus comprising: an apparatus main body; a driving-force generating portion disposed in the apparatus main body and generating a driving force; a developer cartridge configured to be detachably mounted in the apparatus main body and to accommodate developer, the developer cartridge comprising: a drive member configured to be driven to move by the driving force when the developer cartridge is mounted in the apparatus main body; and a display portion configured to move together with the drive member, the display portion displaying identification information relating to the developer cartridge in an optically readable manner; a detecting portion that optically detects the identification information when the display portion is in a first position, and that optically detects presence or absence of the developer in the developer cartridge when the display portion is in a second position different from the first position, the detecting portion comprising: a light-emitting portion that emits light toward the first position; a first light-receiving portion that receives the light that is emitted from the light-emitting portion and reflected by the display portion when the display portion is in the first position, and a second light-receiving portion that receives the light that is emitted from the light-emitting portion and that passes through the first position when the display portion is in the second position; and an information determining portion that determines information on the developer cartridge based on the identification information detected by the detecting portion.