Patent ID: 7574151

Claim:
A smoke detecting device comprising: a light-emitting portion that emits light; a light-receiving portion that receives scattered light resulting from the light which the light-emitting portion emits being scattered by smoke generated from a recording medium on which flash-light is irradiated from a flash fusing device; and a judging section that acquires a light amount signal of the received light, from the light-receiving portion, and that judges, on the basis of the light amount signal, whether or not smoke has been generated from the recording medium on which flash-light is irradiated from the flash fusing device, and the judging section judges that smoke has been generated from the recording medium in a case in which a value of the light amount signal reaches a predetermined reference value, the judging section changing the predetermined reference value in accordance with a ratio of an area of a formed toner image on the recording medium with respect to a predetermined unit area of the recording medium; and the light that the light-emitting portion emits passing through a space between the flash fusing device and the recording medium.