Hitachi, Ltd.

Tetsu Ohishi

Hiroki Yoshikawa

Koji Hirata

Daisuke Imafuku

Takanori Hisada

Yoshie Kodera

Naoyuki Ogura

Hideo Tanide

Toshimitsu Watanabe

Masahiko Yatsu

Satoshi Ouchi

Masakazu Sagawa

Shigeru Mori

Taro Imahase

Tomohiro Miyoshi

Takahiko Yoshida

Akinori Maeda

Jun Matsumoto

Nobuo Masuoka

Nobuaki Kabuto

Toshiaki Kusunoki

Mutsumi Suzuki

Takesuke Maruyama

Koji Suso

Yukio Fukui

Go Uchida

Yuichi Sawai

Masaji Ishigaki

Kyohei Fukuda

Hidenao Kubota

Kazunari Nakagawa

Junichi Ikoma

Atsuo Osawa

Takeshi Igarashi

Akira Takahashi

Yutaka Matsuda

Hiroshi Jitsukata

Motoyuki Miyata

Masaki Nishikawa

Nobuhiro Konuma

Yoshimasa Yokoyama

Kiyoshi Wada

Maki Furui

Satoshi Ishizuka

Goro Ohnishi

Tohru Mori

Takashi Iwata

Hisashi Kabe

Tutomu Simada

Naoko Kubo

Kohsuke Ozeki

Yoshinori Matsumura

Yasuhiko Komatsu

Nobuhiro Tokusyuku

A projection image display device is disclosed in which a trapezoidal distortion and/or aberration are restrained when an image is enlarged and projected obliquely onto a screen. An image generator is connected to an optical system base in such a manner that at least an inclination thereof (on an axis parallel to X axis) with respect to a vertical line and a distance thereof in forward and backward direction (Z axis direction) can be adjusted by an adjusting mechanism. Further, a projecting lensas a first optical system and a free-form curved surface mirror as a second optical system are fixed to the optical system base. The free-form curved surface mirror is rotatable (on an rotary axis parallel to X axis) with respect to the vertical line at a substantial center of the free-form curved surface mirror.

Projecting optical unit and projecting type image display apparatus therewith

An image display apparatus includes an image generation source, optics for projecting in an enlarged form the image generated by the image generation source, and a transmissive screen for displaying the image projected from said optics. The transmissive screen includes a Fresnel lens sheet disposed at an image generation source side, and a diffusing sheet disposed at an image-watching side in order to diffuse image light at least in a horizontal direction of the screen. The Fresnel lens sheet has a plurality of entrance-side prisms formed at the image generation source side, and a plurality of exit-side prisms formed at the image-watching side, and the Fresnel lens sheet emits lights in a first direction and a second direction. The first direction is almost parallel to a central axis of the Fresnel lens sheet, and the second direction extends toward the central axis.

Screen, fresnel lens sheet used for the same, and image display apparatus using the same

A Fresnel lens sheet used for an image display device is disclosed. The Fresnel lens sheet is provided with a first prism group in an area of a light entrance plane of the Fresnel lens sheet where the incident angle of light is equal to or more than a predetermined incident angle and a second prism group in an area of a light entrance plane of the Fresnel lens sheet where the incident angle of light is less than the predetermined value.

Image display device and Fresnel lens sheet used therefor

A projection display is capable of suppressing both the trapezoidal distortion of an enlarged image projected on a screen by oblique projection and aberrations resulting from oblique projection and includes a projection optical system provided with lenses that can be easily manufactured and assembled. The projection optical system for obliquely projecting an image formed by a display device on the screen includes a free curved lens having a rotationally asymmetric free curved surface. The free curved lens has fringing parts having outlines of a shape coinciding with an arc of a circle having the center on the optical axis of the free curved lens.

Projection display, projection optical system and transmission lens or free curved lens

Image disturbance called speckle noise occurs when an image generator has a small effective screen size and a projection lens has a small effective diameter. The present invention is intended to reduce speckle noise. In an optical projector, a viewing angle enlarging ember () for enlarging viewing angle or a scattering member () for scattering image light is disposed near an image display device (), such as a liquid crystal panel. Speckle noise can be reduced, suppressing the deterioration of resolution and contrast.

Optical projector and image display apparatus using the same

To eliminate or otherwise reduce non-uniform brightness of an image of a display apparatus, an image is projected through a projection optical system having a projection lens (), curved surface reflection mirrors (and), and a reflection mirror () onto a rear surface of the rear-surface projection type screen (). The rear-surface projection type screen includes a Fresnel lens sheet (), wherein the prism surfaces of the Fresnel lens are formed in an aspheric configuration, thereby letting the light beams from the screen to exit at an exit angle of about zero (0) degree relative to a line perpendicular to the screen surface, over most of the entire surface thereof. It is possible to obtain a projection image that having uniform brightness in an image display apparatus while maintaining a thin cabinet () profile.

Image display apparatus, as well as, Fresnel lens sheet and screen to be used therein

An image that has been displayed on the display screen of an image generator is first passed through a projection lens section consisting of a front group and a rear group. Next after being reflected on the reflecting surface of a free-form surface mirror, the image is further reflected by a planar reflecting mirror and then obliquely projected from the lower section of a projection screen onto the screen. The front group of the projection lens section is provided for enlarging the image. In order to correct aberration due to oblique projection onto the projection screen, the rear group uses a free-form surface lens that forms a concave shape with respect to the exit side of light from the lens. The free-form surface mirror corrects trapezoidal distortion due to oblique projection onto the projection screen. The free-form surface lens in the rear group of the projection lens section can accommodate changes in environmental conditions by using one edge as a reference edge and rendering the other edge expandable. The free-form surface mirror can likewise use one edge as a reference edge and render the other edge expandable. For adjustment, the free-form surface mirror can also be pivoted about the reference edge.

Projection type image display

In a Fresnel screen for displaying an image, comprising, a screen surface, and a reverse surface opposite to the screen surface in a thickness direction of the screen to be prevented from facing to the viewer, the Fresnel screen has first prism surfaces extending to have respective longitudinal arc-shapes juxtaposed with each other as seen in the thickness direction to deflect light beams for forming the image in at least one of directions perpendicular to each other as seen in the thickness direction, and second prism surfaces extending to have respective longitudinal shapes juxtaposed with each other as seen in the thickness direction to deflect at least a part of the light beams in at least one of the directions perpendicular to each other as seen in the thickness direction.

Image display, Fresnel lens and screen

In the image display device, a projection lens including a plurality of lenses for enlarging an image from an image display element is constituted of a front group and a rear group. The rear group includes at least one free-shaped-surface lens including a surface having a rotationally asymmetrical shape. Furthermore, the device includes at least one free-shaped-surface mirror having a rotationally asymmetrical reflection surface. Accordingly, a set can be formed to be compact while correcting trapezoidal distortion and aberration.

Projection optical unit and projection type video display device using the unit

The present invention provides a technique suitable for making a set more compact by realizing reduction in height and reduction in depth. An image display apparatus of the present invention includes a reflecting mirror () for reflecting the image sent from a projection lens (), and guiding the image to a transmissive screen (). The reflecting-mirror () includes a planar mirror section () for reflecting, of the entire image exiting the projection lens (), only image portions projected onto the upper section of the transmissive screen (), and a Fresnel mirror section () with multiple reflective prisms for reflecting only image portions projected onto the lower section of the screen ().

Image display apparatus, and transmissive screen and reflecting mirror used for same

The present invention provides a technology suitable for shortening a depth of a image display apparatus while obtaining a picture of high quality. According to the invention, a total reflection prism portion is provided on a side of a Fresnel lens sheet toward a picture source. The total reflection prism portion reflects an incident light to a direction toward an optic axial center of the Fresnel lens sheet to have the same outgoing. On the other hand, a first refractive prism portion, by which light of a predetermined incident angle or less is refracted to outgo to a direction along an optical axis of the Fresnel lens sheet, and a second refractive prism portion, by which light reflected to the direction toward the optic axial center of the Fresnel lens sheet is changed to the direction along the optical axis.

Screen, a fresnel lens sheet used for the screen, and an image display apparatus using the screen

Images that are bright even on the periphery of a transmissive screen are obtained by reducing reflection loss of the screen when the screen incident angle of the image light entering the upper left and right ends of the screen increases. Incident-side prisms (), each having at least a plane-of-incidence (c) onto which light comes in, an exit face (d) from which the light that has come in from the plane-of-incidence exits after being refracted, and a refractive face (e) on which the light that has exited from the exit face is refracted and then guided to the image-viewing side of the Fresnel lens sheet (), are provided in the range where the incident angle of the incoming light becomes equal to or greater than approximately 40 degrees.

Screen, fresnel lens sheet used therefor, and image display apparatus using the same

The present invention provides a screen suitable for reducing the longitudinal dimension of a set. The present invention includes two prism sections. One is a totally reflective prism section () provided at the image generation source side of a Fresnel lens sheet (). The other is a refractive prism section () provided at the image-watching side of the Fresnel lens sheet. The refractive prism section () includes a refractive face (e) for refracting incident light and making the light exit toward the image-watching side, a plane (f) approximately parallel to the principal plane of the Fresnel lens sheet, and a connection face (g) for continuously forming the face (e) and the plane (f).

Screen, Fresnel lens sheet used for the same, and image display apparatus using the same

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Hiratsuka, Japan

Tetsu Ohishi