Hitachi Koki Co., Ltd.

Ricoh Printing Systems, Ltd.

Kazutaka Setoma

Takeshi Mochizuki

Susumu Tateyama

Satoru Wada

The invention aims at provision of an optical scanner in which an optics required for equalizing an optical magnification in a scanning range is produced with high accuracy, so that intervals among a plurality of scanning lines on a to-be-scanned surface are even in the scanning range. The scanning optics includes a refraction surface and a reflection surface whose sub-scanning-direction curvature radii vary continuously. The reflection surface is disposed on the to-be-scanned surface side of the refraction surface. The curvature radius of the reflection surface varies symmetrically with respect to the optical axis, and the curvature radius of the refraction surface varies asymmetrically with respect to the optical axis.

Optical scanner and image forming apparatus using the same

In an optical scanning apparatus, a light beam emitted from a light source is deflected and scanned by a light deflecting member, and then scanned and imaged with substantial speed uniformity onto a medium to be scanned by a scanning optical element. The apparatus is configured so that, when the angle formed by the light beam that is deflected and scanned and the optical axis of the scanning optical element is &#x3b8;, the amount of positional deviation due to deviation from speed uniformity of the light beam on the medium to be scanned is &#x3b5;(&#x3b8;), the spatial scan density on the medium to be scanned is P, and the maximum of an absolute value of the angle &#x3b8; is &#x3b8;o, an expression of |d&#x3b5;(&#x3b8;)/d&#x3b8;|&#x2266;5.0&#xd7;10/P&#x3b8;o holds.

Optical scanning apparatus and image forming apparatus

In an optical scanner, while a plurality of lens elements comprise scanning lens optics, the angle (&thgr; of the line dropped normal to the first face of a lens element ( ) positioned the closest to the medium to be scanned which is directed to a light deflecting means at the point where the principal ray of a light beam incident at the scan start end crosses the first face is generally equal to the angle (&thgr; &prime;) of the line dropped normal to the second face of the lens element which is directed to the medium to be scanned at the point where the principal ray crosses said second face, and the angle (&thgr; ) of the line dropped normal to the first face at the point where the principal ray of a light beam incident at the scan finishing end crosses said first face is generally equal to the angle (&thgr; &prime;) of the line dropped normal to said second face at the point where the principal ray crosses the second face.

Optical scanner

In an optical scanner, coupling lens system includes a first optical element as at least one optical element other than the optical element located the farthest away from a light source, the first optical element being made of a material having substantially no power and a negative temperature coefficient of refractive power, and scanning lens system includes at least one second optical element made of a material having positive power and a negative temperature coefficient of refractive index.

Growing community of inventors

Ibaraki, Japan

Kazutaka Setoma