Patent ID: 7356269

Claim:
An electrophotographic image forming apparatus having a waste toner sensing unit in which waste toner occurring during a series of processes of forming an image is stored, wherein the waste toner sensing unit comprises: a light-emitting portion installed opposite to a light-receiving portion, and adapted to radiate light on the waste toner container, the waste toner container being placed between the light emitting portion and the light receiving portion, and the light receiving portion receiving light irradiated from the light-emitting portion that passes through the waste toner container and outputting a voltage corresponding to the amount of received light; an actuator installed in a main body where the waste toner container is mounted between the light-emitting portion and the light-receiving portion, the actuator intercepting light irradiated from the light-emitting portion when the waste toner container is not mounted in the main body, and not intercepting light when the waste toner container is mounted in the main body; a controlling portion which controls the waste toner sensing unit to compare a voltage output from the light-receiving portion with a preset voltage and to determine, based on the voltage output, whether the waste toner container is mounted in the main body, and an amount of toner in the waste toner container when the waste toner container is mounted in the main body, and to display a message in accordance with a comparison result; and a message displaying portion which displays a message to a user in response to a control signal transmitted from the controlling portion.