Image forming apparatus with laser scanning components positioned for enhanced compactness

An image forming apparatus comprising:

• a plurality of photosensitive members;
• a scanner unit configured to scan said photosensitive members with laser beams in accordance with image information, wherein said scanner unit includes light sources corresponding to said photosensitive members, respectively, a rotatable polygonal mirror configured to reflect and deflect the laser beams emitted from said light sources, a frame configured to support said rotatable polygonal mirror, a plurality of reflecting members configured to reflect the laser beams, respectively, reflected by said rotatable polygonal mirror, and a cover configured to cover an opening of said frame, wherein said cover is provided with passing portions through which the laser beams pass to an exterior of the scanner unit;
• and
• a fixing device configured to fix, on a recording material, toner images formed on said photosensitive members and then superposed on the recording material,
• wherein with respect to a vertical direction, said scanner unit is located above said photosensitive members,
• wherein selected ones of the laser beams emitted from said light sources are reflected by said rotatable polygonal mirror toward a side where said fixing device is provided, and remaining ones of the laser beams are reflected by said rotatable polygonal mirror toward a side opposite from the side where said fixing device is provided,
• wherein of the selected ones of the laser beams reflected by said rotatable polygonal mirror toward the side where said fixing device is provided, and with respect to a first reflecting member provided at a position remotest from said rotatable polygonal mirror toward the side where said fixing device is provided among said plurality of reflecting members, the laser beam reflected toward the first reflecting member travels downward relative to an imaginary line connecting rotational axes of said photosensitive members as seen in a rotational axis direction of one of said photosensitive members,
• wherein of the remaining ones of the light beams, and with respect to a second reflecting member provided at a position remotest from said rotatable polygonal mirror toward the side opposite from the side where said fixing device is provided among said plurality of reflecting members, the light beam reflected toward the second reflecting member travels upward relative to the imaginary line as seen in the rotational axis direction,
• wherein a rotational axis of said rotatable polygonal mirror is supported by said frame at a supporting portion of said frame,
• wherein with respect to the vertical direction, said cover is located between said supporting portion of said frame and said plurality of photosensitive members,
• wherein with respect to the vertical direction, said supporting portion of said frame, said rotatable polygonal mirror, said cover, and said plurality of photosensitive members are arranged in this order, and
• wherein an optical path length from said rotatable polygonal mirror to said first reflecting member is longer than an optical path length from said rotatable polygonal mirror to said second reflecting member.