Hitachi, Ltd.

Daisuke Imafuku

Hiroki Yoshikawa

Koji Hirata

Tetsu Ohishi

Takanori Hisada

Naoyuki Ogura

Masahiko Yatsu

Hidehiro Ikeda

Kazunari Nakagawa

Shuji Kato

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

Both ends of a transparent cover which is formed of a curved member are fitted to a lens guard and a mirror guard, and a free-shaped surface mirror and a free-shaped surface lens are housed in a sealed space defined within a projection type image display device.

Projection type image display device

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

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

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

A screen is hung from a screen frame with hanging members bonded to the upper side of a front sheet. Supporting members are disposed on the lower side of the front sheet and, by mounting a Fresnel lens sheet on the supporting members, a tension is given by its weight to the front sheet in the vertical direction. Further, a tension in the horizontal direction is given to the front sheet. Long holes are so formed in the hanging members that the hanging members on the right and left sides of the screen by expansion or contraction of the screen are made greater in the extent of shifting in the horizontal direction than the hanging member in the central part.

Projection type image display apparatus

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

The present invention provides a technology that makes it possible to display high-quality images by reducing a reflection loss of the image light entering the upper left and right ends of a transmissive screen. At the image generation source side of the Fresnel lens sheet, a totally reflective prism section () is provided that totally reflects incident rays of light and causes the light to exit toward the image-watching side. At the image-watching side of the Fresnel lens sheet (), a refractive prism section () is also provided that refracts the light entering from the totally reflective prism section () and causes the light to exit toward the image-watching side. The refractive prism section () has a roughed refractive face.

A total reflecting prism portion is formed on an image generation source side of a Fresnel lens sheet which constitutes a rear projection type screen. The total reflecting prism portion is formed in an area in which the angle of incidence of a projection image projected from an optical part on the Fresnel lens sheet is at least about 40&#xb0;. The total reflecting prism portion causes incident light to be outputted as output light at a predetermined output angle by a total reflection phenomenon after a first refraction phenomenon. Further, a refracting prism portion is formed on an image monitoring side of the Fresnel lens sheet. The refracting prism portion is formed in an area opposed to the portion where the total reflecting prism portion is not formed. The refracting prism portion causes incident light to be outputted as output light at a predetermined output angle by a second refraction phenomenon.

Image display device, rear projection type screen used in image display device, Fresnel lens sheet, and method of making Fresnel lens sheet

A total reflecting prism portion is formed on an image generation source side of a Fresnel lens sheet which constitutes a rear projection type screen. The total reflecting prism portion is formed in an area in which the angle of incidence of a projection image projected from an optical part on the Fresnel lens sheet is at least about 40&#xb7;. The total reflecting prism portion causes incident light to be outputted as output light at a predetermined output angle by a total reflection phenomenon after a first refraction phenomenon. A refracting prism portion is formed on an image monitoring side of the Fresnel lens sheet. The refracting prism portion is formed in an area opposed to the portion where the total reflecting prism portion is not formed. The refracting prism portion causes incident light to be outputted as output light at a predetermined output angle by a second refraction phenomenon.

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Fujisawa, Japan

Daisuke Imafuku