Dainippon Screen Mfg. Co., Ltd.

Takeshi Sugata

Junichi Oka

Yoshikazu Kataoka

Zenji Wakimoto

Kenji Kawai

A scanner scans an original 6 divided into a plurality of regions in a main scanning direction reading image information. The scanner is equipped with light receiving units consisting of a plurality of CCDs arranged in the main scanning direction having a corresponding array of pixels that respond to an image of the original focused on the surface of the array by a plurality of lenses 12 arranged in the main scanning direction. A focal length f of the lens 12 satisfies the following formula, that is,

Image reading apparatus

An optical beam scanning system is constructed with less optical elements. A light beam (B.sub.1) of parallel rays passes through a first image-forming system (L.sub.1). The first image-forming system consists of a cylindrical lens (2) having a refracting power in a direction equivalent to a main scanning direction (X) and a spherical convex lens (3). Focuses of the cylindrical lens and the spherical convex lens are within a prescribed allowance. A light beam (B.sub.11) passing through the spherical lens has a character of parallel rays within a vertical plane and a character of convergent rays within a horizontal plane to be focused on a deflection surface (4a). A reflected light beam (B.sub.2) is finally focused on a surface-to-be-scanned (8) through a second image-forming system (L.sub.2).

Optical beam scanning system

An apochromat optical system for a photoengraving process comprises a first lens group which includes a first lens having a positive power, a second lens made of Kultz flint glass having a negative power and a third lens in the form of a meniscus having a positive power. The first to third lenses are successively disposed in order starting from the object side. A second lens group includes the substantially same configuration of lenses as in the first lens group. The lenses of the first and second lens groups are approximately symmetrical with respect to the stop. Accordingly, the system has a high aperture ratio and small curvature of a saggital and meridional image field which can reduce an astigmatic difference in a peripheral part of an image.

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Hikone, Japan

Takeshi Sugata