Optical beam scanning device, image forming apparatus, optical beam scanning method

A light beam scanning device, comprising:

• plural light sources means for emitting light fluxes passing through positions different from each other in a sub-scanning direction;
• first light flux processing means for including a lens having a negative power in the sub-scanning direction,
• second light flux processing means for being positioned at a more downstream side than the first light flux processing means in a direction of light beam travel and has a lens having a positive power in the sub-scanning direction;
• support means for having a long hole formed to extend in parallel with an optical axis direction of the second light flux processing means, for supporting the lens of the second light flux processing means;
• guide means for being inserted in the long hole of the support means, for guiding the support means to be position-adjustable in the optical axis direction;
• and
• light scanning means for deflecting light emitted from the plural light sources and passed by the first and second light flux processing means and scanning the light in a main scanning direction perpendicular to the sub-scanning direction.

An optical beam scanning method of an optical system that includes a plural light sources, a lens having a positive power in the sub-scanning direction, a support part that has a long hole formed to extend in parallel with an optical axis direction of the optical system and supports the lens of the optical system, a guide member that is inserted in the long hole of the support part and guides the support part to be position-adjustable in the optical axis direction, the method comprising:

• giving, a negative power to the light fluxes emitted from the plural light sources by lens having a negative power in the sub-scanning direction;
• giving a positive power to the light flux, to which the negative power has been given, by a lens that is adjusted an interval of the light fluxes emitted and passed by the optical system in the sub-scanning direction by moving the support in the optical axis direction;
• and
• deflecting the light flux, to which the positive power has been given, by the rotary deflector and scanning it in a main scanning direction perpendicular to the sub-scanning direction.