Fuji Photo Optical Co., Ltd.

Fujinon Corporation

Fujifilm Corporation

Kimiaki Nakazawa

Tomoyuki Baba

Hiroshi Yamada

Masaru Amano

Akiko Nagahara

Fumio Watanabe

Kazuya Yoneyama

Kenzo Sado

Disclosed are a projection lens that has a small size, a simple inner focus structure, a high optical performance, and a wide angle of view of about 75 degrees or more, and a projection display device. A projection lens includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power arranged in this order from a magnification side. A fifth lens arranged closest to a reduction side in the first lens group is moved along an optical axis to adjust focus. The projection lens satisfies the following conditional expression:3.0&#x3c;&#x3c;6.0

Projection lens and projection display device using the same

A projection zoom lens is provided and includes: in order from the magnification side, a positive first lens group performing focusing with being fixed during power-varying and having a focusing function; a negative second lens group, a negative third lens group, and a positive fourth lens group, which are moved with correlation during the power-varying; and a positive fifth lens group Gfixed during the power-varying. An aperture diaphragm is fixed between the fourth lens group and the fifth lens group during the power-varying. In addition, the expression of 1.7&#x3c;Bf/f&#x3c;3.0 is satisfied, where f is a focal length of the whole system, and Bf is a back focal length (air conversion distance) of the whole system.

Projection zoom lens and projection type display device

A negative first group Gis fixed when a power of the projection zoom lens varies and has a focusing function. A positive second group G, a positive or negative third group G, a positive fourth group Gand a positive or negative group Gmove with a mutual relationship. A sixth group Gfunctions as a relay lens. The fifth group Gincludes a cemented lens formed by cementing a negative meniscus lens Lhaving a convex surface directed to the magnification side, a negative lens Land a positive lens Lin order from a magnification side, and a positive lens Lhaving a convex surface directed to a reduction side. Also, an expression |F|/F&#x3e;4.5 is satisfied where F denotes a focal length of the projection zoom lens at a wide-angle end and Fdenotes a focal length of the fifth group.

Projection zoom lens and projection-type display device

A zoom lens for a projection display device includes, in order from the enlarging side, a first lens group having negative refractive power and that is stationary during zooming, second and third lens groups having positive refractive power, a fourth lens group that has refractive power that is much weaker in absolute value than the refractive powers of the other lens groups, and a fifth lens group having positive refractive power and that is stationary during zooming. The second, third, and fourth lens groups move with coordinated movements continuously toward the enlarging side during zooming from the wide-angle end to the telephoto end of the zoom range. The zoom lens satisfies certain conditions related to focal lengths of the zoom lens and lens groups and distances along the optical axis. A projection display device uses the zoom lens.

Zoom lens and projection display device using the zoom lens

A polarized beam splitter includes an inclined intermediate layer between two glass prisms. The intermediate layer includes an adhesive layer and a polarized light separating membrane. The intermediate layer may be wedge-shaped in order to compensate for or to cancel astigmatism of light transmitted by the polarized beam splitter caused by the inclination of the intermediate layer. The polarized beam splitter may also be formed with the refractive indexes of the glass and the adhesive of the adhesive layer chosen to reduce astigmatism. Embodiments of three-color projection image display devices that use the polarized beam splitter are also disclosed. The three-color projection image display devices may use one or three polarized beam splitters with a Philips prism or use two polarized beam splitters with a COLORQUAD.

Polarized beam splitter and projection-type image display using it

An afocal, wide converter lens is provided in order to shorten the focal length of a main lens, thereby shortening the projection distance that is needed to fully illuminate a given screen size when the wide converter lens is attached to the enlarging side of a main lens which functions as a projection lens of a projection apparatus. The wide converter lens is formed of, in sequential order in the direction from the enlarging side to the reducing side of the main lens, a lens element of positive refractive power, at least one lens element of negative refractive power, a positive meniscus lens element having its convex surface on the enlarging side, a negative meniscus lens element having its concave surface on the enlarging side, and a cemented lens of overall positive refractive power. Various conditions are satisfied in order that the wide converter lens does not degrade the optical performance of the main lens.

Wide converter lens

A transparent member having refractive power as a result of curved surface thereon is used in one or more light paths of a three-color projection device in order to correct for the lateral color aberration of the projection lens. The transparent member is positioned between one or more optical modulation element(s) and the beam combining prism of a prism optical system, or alternatively, is on or affixed to the beam combining prism surface. When correcting an image that is enlarged by the projection lens, the curved surface of the transparent member should be convex and positioned on the side of the transparent member nearest the display panels. The focal length of a correction lens that optimally corrects the lateral color of the projection lens depends on the maximum image height at the image input display panel, the lateral color aberration generated by the projection lens, and the air conversion length from the image input display panel to the on axis position of the curved surface.

Projection device comprising a correction lens arranged between a prism optical system and at least one of three optical modulation elements

A teleconverter lens is disclosed, for attachment to the enlarging side of a projection lens, wherein aberrations generated by a negative focusing lens group positioned at the enlarging side of the projection lens are not made greater by the teleconverter lens. The teleconverter lens is substantially afocal and is formed of a front lens group having negative refractive power and a back lens group having positive refractive power. The front lens group is formed of two series of combined lenses, each combined lens being a lens element of positive refractive power and a lens element of negative refractive power that are joined. The back lens group is a single combined lens formed of a lens element of positive refractive power that is joined to a lens element of negative refractive power. The teleconverter lens is detachably attachable at its back side to the enlarging side of the projection lens.

Teleconverter lens

A wide-angle lens is disclosed having only three lens groups of negative, positive, and positive refractive power, in order from the object side, and having only six lens elements with refractive power. The first lens group is formed of a meniscus lens with its convex surface on the object side, the second lens group is formed of a biconvex lens, and the third lens group is formed of, in order from the object side, a biconcave lens element, a positive lens element having a convex surface on the image side, a positive lens element having a convex surface on the image side, and a positive lens element having a convex surface on the object side. A diaphragm is arranged between the second lens group and the third lens group. Furthermore, specified conditions are satisfied in order to provide a compact wide-angle lens that is well corrected for aberrations and has a sufficient back focal length to insert additional optical components.

Wide-angle lens

A retro focus lens having three lens groups arranged, in order from the longer conjugate length side of the lens, as follows: a negative first lens group G.sub.1, a positive second lens group G.sub.2, and a positive third lens group G.sub.3. The first group G.sub.1 includes, in order from the longer conjugate length side of the lens, a first lens element L.sub.1 of small positive refractive power and made of plastic with an aspherical surface, a second lens element L.sub.2 of negative refractive power that is made of glass and has a concave surface facing the shorter conjugate length side of the lens, and a third lens element L.sub.3 of negative refractive power with a concave surface facing the shorter conjugate length side of the lens, there being no additional lens elements between the first lens element L.sub.1 and the third lens element L.sub.3. By satisfying preferred conditions, favorable chromatic aberrations and distortion are attained while achieving a high resolution and a sufficiently large back focus to allow the lens to be used as a projection lens for liquid crystal color projectors.

Retro-focus lens

To correct on-axis chromatic aberration of a projection lens easily and at low cost by using a transparent plate between an optical modulator for a primary color component and a beam combining optical system. When a standard projection lens 11 having a medium focal length is used, parallel-plane glass plates 27, 28, and 29 of the same thickness (1 mm for example) may be inserted in each component beam. However, when the projection lens is changed to one having a different focal length, at least one of the parallel-plane glass plates is replaced in order to suppress the occurrence of on-axis chromatic aberration for that color component caused by the change in focal length.

Projector apparatus

A super wide angle lens, having a viewing angle greater than 120 degrees, and an F-number of about 1.2 is disclosed. The lens is formed of a first lens group G.sub.1 of negative refractive power, a second lens group G.sub.2 of positive refractive power, and a third lens group G.sub.3 of positive refractive power. The lens is designed so that the lens elements used in the lens groups may be easily and economically manufactured. The first lens group has a first lens element L.sub.1 composed of a negative meniscus lens with its convex surface on the object side, and a second lens element L.sub.2 composed of a negative meniscus lens with its convex surface on the object side. The second lens group includes a third lens element L.sub.3, that is biconcave, cemented to a fourth lens element L.sub.4 that is biconvex. The third lens group has four lens elements: a fifth lens element L.sub.5 composed of a negative meniscus lens, with its convex surface on the object side; a sixth lens element L.sub.6 composed of a biconvex lens cemented to the fifth lens element; a seventh lens element L.sub.7 composed of a negative meniscus lens, with its convex surface on the object side; and an eighth lens element L.sub.8 composed of a biconvex lens cemented to the seventh lens element.

Super wide angle lens

Negative, positive, and positive lens groups are disposed successively from the larger conjugate length side, and focal length adjustment is effected by the convex lens disposed on the smallest conjugate length side of the first lens group, thereby yielding a long back focus and a telecentric characteristic, decreasing distortion and chromatic aberration, and simplifying the focusing structure. Successively from the larger conjugate length side, a first lens group G.sub.1 having a negative refracting power and including a convex lens L.sub.5 disposed on the smallest conjugate length side, a second lens group G.sub.2 having a positive refracting power and causing a luminous flux diverged by the first lens group G.sub.1 to become substantially afocal, and a third lens group G.sub.3 having a positive refracting power are disposed, and the convex lens L.sub.5 disposed on the smallest conjugate length side of the first lens group G.sub.1 is moved on an optical axis so as to effect focus adjustment.

Growing community of inventors

Saitama, Japan

Kimiaki Nakazawa