Hitachi, Ltd.

Hitachi Video and Information System, Inc.

Yoshiaki Iwahara

Masanori Ogino

Shoji Kuroda

Yuzo Tamura

Akio Yamamoto

Shuichi Sakamoto

Takeo Yamada

Shigeru Mori

Fumio Inoue

Masanori Oguino

Takashi Itoh

Makoto Kamiya

Yukihiro Kobayashi

Isao Yoshizaki

Shobu Saito

Masutomi Ohta

Hiroshi Kaiwa

Osamu Shuugizono

Syuichi Sakamoto

A rear projection type display system with a transmissive screen. A transparent reinforcing plate is coupled to a lenticular sheet of the screen on the light output side by a connective member to broaden the horizontal diverging angle by 60 degrees or more to the right and left sides. The duty factor of a black stripe formed on the lenticular sheet is set to 60% or more so improve the contrast of an image. The diverging angle at each point of a vertically-diffusing lens for diverging light in the vertical direction is modulated in accordance with the height of each point to offer a proper visual angle range in the vertical direction.

Rear projection type display system

A liquid crystal projection display capable of functioning at a high light capturing efficiency and a high relative corner illuminance comprises a light source means including a light source, a liquid crystal panel means, a projection lens means and a screen means. A liquid lens formed by sealing a liquid in a space between opposite transparent members is disposed near the light source or the real image of the light source to enhance the relative corner illuminance without reducing the light capturing efficiency by multiplying the angle of divergence of light rays emitted by the light source by the reciprocal of the refractive index of the liquid. A first optical system disposed on the entrance side of the liquid crystal panel is provided with a relative corner illuminance enhancing means comprising a first light converging means disposed relatively near to the light source means, and a second light converging means disposed relatively remote from the light source means. The first light converging means enhances the relative corner illuminance on the entrance surface of the second light converging means.

Liquid crystal Projection display

Liquid crystal projection display

A multi-screen projector having unit module projectors stacked at two higher and lower stages, each unit module projector having a screen with a Fresnel sheet unit, a prism sheet unit, and a lenticular sheet unit. By the functions of the Fresnel sheet unit and the prism sheet unit, main output light from higher and lower screens is converged to substantially the same target point. Only one type of metal molds is required for the Fresnel sheet unit as well as the prism sheet unit, thereby reducing the manufacturing cost of the multi-screen projector.

Multi-screen projector

A projection type display device including a CRT with a fluorescent layer and a face glass for projecting an image reflected onto the fluorescent layer through the face glass, a transparent liquid, at least one lens element and onto a screen. The transparent liquid is filled within a space between the face glass of the CRT and the at least one lens element and has a refractive index substantially the same as a refractive index of the face glass of the CRT and the at least one lens element. A light attenuation filter having a transmittance no greater than 0.9 is disposed at a position from the fluorescent layer to the at least one lens element such as between the face glass and the at least one lens element.

Projection type display device

A screen is constituted by one sheet of Fresnel lens and two sheets of lenticular lenses, and the following relationships are fulfilled: 0.9 To&lt;vy.multidot.dy/n and 0.9 To&lt;vx.multidot.dy&lt;3 To where vx and vy denote respectively angles, which are obtained when viewing a projection lens from the side of the lenticular lenses through the Fresnel sheet, dx and dy denote respectively distances between a surface of the Fresnel lens and focal planes of the lenticular lenses, n denotes a refractive index of a medium, and To denotes a pitch of the Fresnel lens, whereby radial two dimensional moire disturbance appearing in a rear projection display can be reduced to one-fifth the amplitude of the prior art one.

Two dimensional moire reduction type projection display

The object of the invention is to provide a large-screen projection-type display using a transmission-type screen, wherein the transmission-type screen is formed of two or more sheets 4, 7, is tilted toward the viewer's side with a small gap kept between the sheets, and is stable relative to the temperature and moisture change of the environment. The front sheet 4 provided on the viewer's side and the Fresnel sheet 7 provided on the projection source side are tilted forward by about 7.degree. toward the viewers. The springs 10 are extended through wires 9 to exert the tension on the front sheet 4 in the vertical direction. At the same time, the springs exert a pressure on the Fresnel sheet 7 in the vertical direction.

Large-screen projection-type display

A support member for supporting a plurality of vertically-arranged Fresnel sheets is fixedly mounted on a lower end portion of a reinforcing sheet. A hanging mechanism hangs the reinforcement sheet and the Fresnel sheets vertically adjustably. An elongated screen is constituted by a plurality of vertically-arranged unit screens, and the overall screen is constituted by a plurality of elongated screens arranged horizontally. A mechanism for preventing the relative displacement of the opposed edges of the elongated screens from each other in a direction perpendicular to the plane of the elongated screen is provided at an effective projection light-absent region where the light projected from projectors onto the screen is not hindered. A mechanism for limiting the absolute displacement of the elongated screens in a direction perpendicular to the plane of the elongated screen is provided at the right and left edges of the elongated screens and is disposed at the effective projection light-absent region. The limiting mechanism includes a plate member having a buckling load resistance, and pins connecting the opposite ends of the plate member respectively to the elongated screen and a fixed position in such a manner that the elongated screens are free to move vertically. A pillar member is used for fixing the end of the plate member, and a space between a support base supporting the unit projectors and the pillar members is used as a maintenance screen.

Unit projectors whose number is n.times.m are arranged in n rows and m columns like a matrix. Unit screens whose number is n.times.m are arranged so that they as a whole form an enormous transmissive screen. Each unit screen is composed of the three layers of a front sheet on a Fresnel sheet on a re-inforcing sheet facing an observer. A front sheet is provided with the shape having a one-dimensional curvature which causes the peripheries of the front sheet and a re-inforcing sheet to be apart from each other when the center of the front sheet is brought in touch with that of the re-inforcing sheet in the unloaded state. Wires smaller in diameter than the pixel size are connected to the left and right sides of the front sheet, springs provide the wires with tension with support members as their support, and the force of the springs is thus provided by way of the wires for the front sheet so that the left and right sides of the front sheet are pressed on the re-inforcing sheet by way of the Fresnel sheet. The boundary part between the unit screens is reduced into a minimum.

A liquid crystal panel type projection display wherein exit light rays from at least one liquid crystal panel are projected onto a screen for display. Lenses are configured with respect to the liquid crystal panel and the screen so as to enable a large projection field angle.

Liquid crystal panel type projection display

A multi-screen projector composed of a plurality of unit module projectors piled up one upon another in the vertical direction. Each unit module projector includes a Fresnel lens sheet, lenticular sheet, and prism sheet interposed therebetween such that a light is incident to the Fresnel lens sheet and outputted from the lenticular sheet. The prism angle of the prism sheet of the unit module projector disposed at a higher position is set larger than that disposed at a lower position, and the main output light from the prism sheet is made at least parallel with the incident light direction or deflected downward relative to the incident light direction.

A rear projection apparatus is disclosed which is provided with at least two optical projection lens units. Two or more projected images are joined to form a single projected image on a screen. A light reflection preventing member is provided on a blocking plate for preventing the adjacent images from overlapping with each other. The reflection preventing member is used for preventing the light, projected onto the blocking plate, from being introduced into the screen, thereby preventing a degradation of contrast.

Rear projection apparatus

In a video projector for projecting a video picture displayed on a Braun tube, the space between the Braun tube and a lens is filled with a medium having a refractive index substantially equal to those of both the glass faceplate of the braun tube and the material of the lens, and the medium is a silicon resin of the mixture of two liquids which is in liquid phase just after the mixing of two or three or above liquids but cured after lapse of a certain time into a gel state, and the lens is supported by a lens holder so that it can be moved freely along the optical axis within the lens holder.

Growing community of inventors

Yokosuka, Japan

Yoshiaki Iwahara