Optical scanning and image forming apparatus with a free-sliding unit for thermal expansion

An optical scanning apparatus comprising:

• a deflection unit that scans beams emitted from a plurality of laser light sources;
• an imaging unit having one or more optical elements for imaging beams scanned by the deflection unit;
• a supporting unit disposed to extend along a main-scanning direction, the supporting unit having a higher rigidity than a rigidity of the imaging unit, the supporting unit having a pair of receiving members that support the imaging unit, in a sub-scanning direction, near both ends, as seen in a main scanning direction, of the imaging unit;
• a bend-adjustment unit having a plurality of height adjusters configured to adjust a height of the imaging unit relative to the supporting unit, the bend-adjustment unit being configured to correct bend of the imaging unit by height adjustment with the height adjusters, the bend-adjustment unit being disposed on the supporting unit at a plurality of positions along the main scanning direction;
• and
• a free-sliding unit configured to enable sliding between at least one of the supporting unit and the bend-adjustment unit and the imaging unit in deformation of the imaging unit so as to secure the deformation of the imaging unit due to temperature changes thereof;
• and
• wherein the free-sliding unit is located between one of the height adjusters and the imaging unit, and wherein the free-sliding unit is configured to engage the supporting unit to align the free-sliding unit relative to the imaging unit;
• and
• wherein the free-sliding unit has a central portion that comes into contact with the one of the height adjusters and the imaging unit, the free-sliding unit has end portions for engaging the supporting unit, the central portion is located between the end portions along the main scanning direction, the end portions are spaced apart from the imaging unit, and the free-sliding unit has a curvature of above R 0.5 at portions between the central portion and the end portions.