Method and apparatus for multi-beam optical scanning capable of effectively adjusting a scanning line pitch

An optical scanning apparatus, comprising:

• a plurality of optical device sets each configured to generate multiple laser light beams;
• and
• a light deflection mechanism configured to deflect the multiple laser light beams from the plurality of optical device sets to form different latent images on respective photosensitive surfaces,
• wherein each set of the plurality of optical device sets includes a prism which is arranged between a coupling lens included in each optical device set and said light deflecting mechanism, said prism being configured to move in a direction to change positions of the multiple laser light beams in a particular direction.

An image forming apparatus comprising:

• a plurality of photosensitive members each having a photosensitive surface;
• a plurality of development mechanisms each configured to develop an image with a different color toner;
• and
• an optical scanning apparatus which comprises:
• a plurality of optical device sets each configured to generate multiple laser light beams;
• and
• a light deflection mechanism configured to deflect the multiple laser light beams from the plurality of optical device sets to form different latent images on respective photosensitive surfaces of the plurality of photosensitive members;
• wherein each set of the plurality of optical device sets includes a prism which is arranged between a coupling lens included in said each set and said light deflecting mechanism, said prism being configured to move in a direction to change positions of the multiple laser light beams in a sub-scanning direction, and
• wherein the different latent images formed on the respective photosensitive surface of the plurality of photosensitive member are developed into visual images with different respective color toners by the plurality of development mechanisms.

An optical scanning method, comprising:

• providing a plurality of optical device sets each generating multiple laser light beams;
• and
• deflecting the multiple laser light beams from the plurality of optical device sets to form different latent images on respective photosensitive surfaces with a light deflecting mechanism,
• wherein each set of the plurality of optical device sets includes a prism arranged between a coupling lens included in each optical device set and said light deflecting mechanism and moving each said prism in a direction to change positions of the multiple laser light beams in a particular direction.