Image forming apparatus to suppress unnecessary exposure of photoconductive body

An image forming apparatus comprising:

• a first photoconductive body;
• a second photoconductive body disposed adjacent to the first photoconductive body along a direction perpendicular to an axial direction of the first photoconductive body and the second photoconductive body;
• a first light source configured to emit a first light beam;
• a second light source configured to emit a second light beam;
• a deflector configured to deflect the first light beam emitted by the first light source and the second light beam emitted by the second light source;
• a scanning optical system configured to image the first light beam deflected by the deflector onto the first photoconductive body, and image the second light beam deflected by the deflector onto the second photoconductive body;
• a first developing unit including a first developing roller configured to supply developer to the first photoconductive body;
• a second developing unit including a second developing roller configured to supply developer to the second photoconductive body;
• an optical sensor configured to detect the first light beam deflected by the deflector;
• a cam configured to press the second developing unit and move the second developing unit to a first position where an optical path of the first light beam from the scanning optical system to the first photoconductive body is opened, and to a second position where the optical path is closed by the second developing unit;
• and
• a controller configured to:
• start driving the deflector;
• when the second developing unit is in the second position to close the optical path, cause the first light source to emit the first light beam, thereby obtaining a detection signal of the first light beam from the optical sensor;
• and
• after obtaining the detecting signal, control the cam to move the second developing unit to the first position, thereby keeping the second developing unit from closing the optical path.

An image forming apparatus comprising:

• a photoconductive body;
• a drawer configured to support the photoconductive body and to be pulled out in a direction perpendicular to an axial direction of the photoconductive body;
• a light source configured to emit a light beam;
• a deflector configured to deflect the light beam emitted by the light source, the deflector including a polygon mirror and being configured to scan the light beam in a scanning direction;
• a scanning optical system configured to image the light beam deflected by the deflector onto the photoconductive body;
• a developing unit including a developing roller configured to supply developer to the photoconductive body, the developing roller being configured to be in contact with the photoconductive body when the developing unit is in the first position, and be separated from the photoconductive body when the developing unit is in the second position;
• an optical sensor configured to detect the light beam deflected by the deflector;
• a cam configured to press the developing unit and move the developing unit to a first position where an optical path of the light beam from the scanning optical system to the photoconductive body is opened, and to a second position where the optical path is closed by a wall of the developing unit, the developing unit being movable from the first position toward the second position relative to the photoconductive body in a movement direction;
• and
• a controller configured to:
• start driving the deflector;
• when the developing unit is in the second position, to close the optical path by the wall of the developing unit by movement of the wall in the movement direction, cause the light source to emit the light beam, thereby obtaining a detection signal of the light beam from the optical sensor;
• and
• after obtaining the detection signal,
• control movement of the cam to move the developing unit to the first position, thereby keeping the developing unit from closing the optical path by the wall thereof.