Optical scanning apparatus having support members outside the housing for supporting a housing and reflectors, including a pair of ribs and warp preventing member engage with groove formed by ribs, and an image forming apparatus including the same

An image forming apparatus for forming a color image, comprising:

• an optical scanning apparatus comprising:
• a housing that positions and holds a plurality of light sources emitting light beams, a deflection mirror that deflects the light beams to perform main scanning, and at least one of optical image forming elements closest to the deflection mirror to form images on respective image carriers,
• a plurality of reflectors situated outside the housing so as to guide the light beams exiting said housing to the respective image carriers;
• a pair of support members that face each other to support said housing in a main scanning direction;
• a support frame that couples said support members to each others;
• a pair of ribs extending in the main scanning direction provided on a back surface of the said housing;
• and
• a warp-preventing member inserted into and engaged with a groove formed by the ribs,
• wherein said support members support said reflectors to be outside the housing by bridging said reflectors between said support members, and
• wherein relative positions of the reflectors are arranged and aligned in a cross-sectional plane perpendicular to the main scanning direction between said support members;
• and
• an image forming part that develops electrostatic latent images formed on the image carriers by said optical scanning apparatus by applying different color toners corresponding to respective image carriers, and forms the color image by sequentially transferring and overlapping the developed toner images onto a transfer member so as to form the color image.