Optical scanner configured so a principal ray of an incident beam from a light source to a deflector and a principal ray of a scanning beam from the deflector to a scanned surface travel on opposite sides of an optical axis of optical element(s) having transmissive surfaces both concave toward the deflector in sub-scanning section, and image forming apparatus using the same

#The present invention relates to an optical scanner and an image forming apparatus using the same. In particular, though not exclusively, the present invention relates to an optical scanner suitable for an image forming apparatus having an electrophotographic process.

#In a conventional optical scanner used in a laser beam printer (LBP) and so on, a light beam that is optically modulated in accordance with an image signal and emitted from a light source device is periodically deflected by a light deflector, for example, a rotating polygon mirror. The light beam is converged into a spot on a surface of a photosensitive recording medium (photosensitive drum) by a scanning optical system having fθ characteristics, and then the surface of the recording medium is optically scanned to carry out image recording.

#FIG. 10 illustrates a schematic view of a conventional optical scanner.

#FIG. 1 illustrates a main scanning sectional view of an optical scanner according to exemplary embodiment 1.

#FIG. 2 illustrates a sub-scanning sectional view of the optical scanner according to exemplary embodiment 1.

#FIG. 3 illustrates ghost light in exemplary embodiment 1.

#The following description of exemplary embodiment(s) is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

#Processes, techniques, apparatus, and materials as known by one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the enabling description where appropriate. For example member formation and manufacturing may not be discussed in detail; however such processes as known by one of ordinary skill in the art and equivalent methods, processes, and materials would fall within the intended scope of exemplary embodiments. For example, materials used for and positioning of optical elements (e.g., lens and mirrors) may not be discussed but materials and positioning techniques as known by one of ordinary skill in the relevant arts is intended to lie within the scope of exemplary embodiments.

#Additionally the actual size of optical elements may not be discussed however any size from macro lenses to nano lenses are intended to lie within the scope of exemplary embodiments (e.g., lenses with diameters of nanometer size, micro size, centimeter size, and meter sizes).