Patent ID: 8879930

Claim:
An image forming apparatus comprising: an image forming portion including image carriers, electrification members, exposure members and developing units for each color, so as to form toner images of individual colors on surfaces of the image carriers, respectively; an intermediate transfer member disposed to face the image carriers so that each toner image formed on the image carriers are transferred and overlaid to form a color image thereon; a light emitting window whose longitudinal direction is a main scanning direction, through which a light beam generated by the exposure member emits to scan and expose a surface of each of the image carriers in the main scanning direction; a window cleaning device including a cleaning member which is moved in a reciprocating manner in the main scanning direction along the light emitting window so as to perform a cleaning operation in which the cleaning member cleans the light emitting window; a controller configured to control operations of the image forming portion and for driving the window cleaning device to perform the cleaning operation at a predetermined time; and a density detecting member capable of detecting image density of a stripe image formed by the image forming portion in a predetermined position on the intermediate transfer member continuously in a vertical scanning direction perpendicular to the main scanning direction, wherein the controller controls the exposure members to emit the light beam through the light emitting window so that the stripe image is formed in the predetermined position when the window cleaning device performs the cleaning operation, so as to form an image defect part on the stripe image, which occurs when the light beam is intercepted by the cleaning member moving along the light emitting window in the main scanning direction, and detects the image defect part by the density detecting member, and the controller determines that the cleaning member stays within a scanning range of the light beam on the light emitting window when a predetermined number of the image defect parts are not formed in the predetermined position in a period from start to end of the cleaning operation.