Ricoh Company, Ltd.

Hirotoshi Nakayama

Kazuhiro Fujita

Yohei Takano

Hibiki Tatsuno

Nobuyuki Arai

Masahiro Itoh

Naoki Nakamura

Shigeaki Imai

Kiichiro Nishina

Muneaki Iwata

Kasumi Nakamura

Shohta Kobashigawa

Asato Tamura

Yoichi Ichikawa

Hiroto Tachibana

Takuei Nishio

Rie Hirayama

There is provided a projection optical system capable of projecting an image formed on an image forming unit on a projection plane, which has an extremely short projection distance and a small size.

Projection optical system including movable lens groups, a non-movable lens group, and a curved mirror

A projection optical system satisfies &#x3b8;1&#x2265;15 (deg) and 3&#x3c;EP/Ym&#x3c;7. &#x3b8;1 is a maximum inclination angle of the reflective surface of each of the micromirrors with respect to the line normal to the image display surface; EP is an entrance pupil distance of the projection optical system; and Ym is a maximum distance in a plane from an optical axis to a point on the image display surface, the plane being a plane in which a light ray propagating from a center of the image display surface toward the projection surface through a center of an aperture stop of the projection optical system exists, the optical axis being an axis shared by a largest number of the plurality of lenses of the projection optical system, the point corresponding to an image on the projection surface.

Projection optical system unit, projection optical system, and projection optical apparatus

A light source device includes: a light source to emit first color light; a fluorescent member having a first region that includes a fluorescent body to convert at least a part of the first color light into second color light different from the first color light when irradiated with the first color light and a second region to transmit the first color light; a wave plate; a reflecting member to reflect the first color light transmitted through the wave plate; and an optical path separating element provided on an optical path between the light source and the fluorescent member and transmit one of the first color light emitted from the light source and reflected light of the first color light by the reflecting member, and reflect another one.

Light source device and image display apparatus

Projection optical system including movable lens groups and image display apparatus

Projection optical system and image display apparatus including a refraction optical system and first and second reflecing surfaces

Projection optical system and image display apparatus

A scanner lens includes a first lens group with a positive refractive power, having a first positive lens and a second negative lens which are cemented, second to fifth lens groups having a third negative lens, a fourth positive lens, a fifth negative lens, and a sixth negative lens, respectively, arranged in order from an object side to an image side, and an aperture stop disposed between the first and second lens groups. The scanner lens satisfies the following three conditions:0.01&#x3c;BF/&#x3c;0.100.50&#x3c;1/&#x3c;9.50.20&#x3c;10/&#x3c;0.90where BF is a back focus of the scanner lens, L is a total lens length, f1 is a focal length of e-line of the first lens group, f is a focal length of e-line of the entire lens system and d10 is an air space between the fifth and six lenses.

Scanner lens, image reader and image forming device

An image-forming lens includes, in order from an object side to an image side, a first group having a negative power as a whole, the first group consisting of a positive meniscus lens having a convex surface on the object side and a negative meniscus lens having a convex surface on the object side, the positive meniscus lens and the negative meniscus lens being cemented, an aperture stop, a second group consisting of a positive meniscus lens having a convex surface on the image side, a third group consisting of a positive meniscus lens having a convex surface on the image side, a fourth group consisting of a lens having a negative power, and a fifth group consisting of a biconcave lens.

Image-forming lens, image reader, and image-forming device

Growing community of inventors

Kanagawa, Japan

Hirotoshi Nakayama