Nalux Co., Ltd.

Nippon Aspehrical Lens Co., Ltd.

Takatoshi Suzuki

Daisuke Seki

Katsumoto Ikeda

Tomohito Kuwagaito

Tingwen Xing

An optical scanning system includes a variable-focus element, an imaging lens and a deflector, wherein the reciprocal of the focal length f of the variable-focus element is changed from 1/fto/f, and for the case that the equation1/={(1/)+(1/)}/2holds, a beam which has passed through the variable-focus element is a divergent beam, and is satisfied, where xrepresents a distance from a virtual image point of the divergent beam to the principal point on the entry side of the variable-focus element, xrepresents a distance from the principal point on the exit side of the variable-focus element to the principal point on the entry side of the imaging lens, and x3 represents a distance from the principal point on the exit side of the imaging lens to an image point.

Optical scanning system

An illumination lens includes a light receiving surface; and a light exit surface. When the axis ofis designated as Z-axis, a position of the bottom of the lens is designated as z=0 and X-axis and Y-axis are defined in a plane which contains z=0 and is perpendicular to Z-axis,is symmetric about YZ-plane and XZ-plane and a cross-sectional area of a cross section ofparallel to XY-plane monotonously decreases with increase in z-coordinate. When the maximum value of z-coordinate onis designated as d and a radius of the cross section ofat z=0 is designated as r, a point (x, y) on a cross section ofat z=0.3is represented by where a and b represent constants and and there exists a point at whichf(&#x3b8;)&#x2266;0.95anda&#x3c;0.5and b&#x3c;0.5

Illumination lens and illumination module

The present invention has the object to make an f&Oslash; lens constituting a scanning optical system such as a laser printer, etc., which is of a single lens configuration, and higher in resolution, thereby providing the f&thgr; lens provided with a lens performance so as to correspond to an A3 paper size or the like. The f&thgr; lens is designed by the aspherical formula as follows:

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Osaka, Japan

Takatoshi Suzuki