Hitachi, Ltd.

Kyohei Fukuda

Soichi Sakurai

Koji Hirata

Yoshiharu Nagae

Shigeru Mori

Yuji Mori

Minoru Hoshino

Hideo Sato

Yoshiro Mikami

Kuniharu Osakabe

Hiroshi Jitsukata

Hiroki Yoshikawa

Nobuhiro Konuma

Masanobu Takata

Takanori Hisada

Tetsu Ohishi

Yasuyuki Kozima

Yasuo Amano

Masayuki Muranaka

Shigeru Inaoka

Isao Yoshizaki

Masahiro Takasaka

Isao Yoshimi

Masaki Yoshii

Yoshiaki Tsuchihashi

Katuyuki Hunahata

Hayao Kozai

Hiroshi Kataoka

Youhei Saito

Tadahiko Hasimoto

In a projection-type display apparatus using light scattering type liquid crystal devices, light from a light source is reflected by a reflecting mirror through a collecting lens; reflected light is converted by a lens into a parallel light beam, which is injected into liquid crystal devices disposed on three sides through a dichroic mirror, the liquid crystal devices coloring an image in red, green and blue; the image is projected on a screen through again the dichroic mirror, the collecting lens and an enlarging lens. Further a photodetector is disposed at a focal point of the collecting lens and a function of adjusting the position of the light source on the basis of a result of this detection is added.

Method for projecting image obtained by using liquid crystal panels and

Method for projecting image obtained by using liquid crystal panels

In a polarization transforming optics having a polarizing beam splitter (PBS) for transforming x-direction incident light flux from a metal halide light source into a single linearly (z direction) polarized light flux beam heading in the y direction and delivering the beam to, preferably, a light valve of a liquid crystal display (LCD) in a coordinate space, the PBS splits the incident light flux from the light source into split light flux beams, separates the split light flux beams into linearly polarized light flux beams having polarizing directions which are orthogonal to each other, and delivers two linearly polarized outgoing light flux beams having polarizing directions which are orthogonal to each other and heading in directions parallel to a polarizing direction plane. One of the two outgoing light flux beams is deflected by a single mirror to have the same heading direction and polarizing direction as those of the other. The PBS is constructed by jointing together, for example, a quadrangular pyramidal prism and two triangular pyramidal prisms. A PBS film is formed at each joint interface and a surface in contact with air of each prism acts as a total reflection mirror surface. No wave plate is used to provide a compact apparatus having a high light utilization efficiency.

Polarization transforming optics, polarizing beam splitter and liquid

A projection-type stereoscopic image display system is disclosed in which a left-eye projection light ray and a right-eye projection light ray are projected from behind a transparent screen thereby to display a stereoscopic image.

Projection type stereoscopic image display system

An optical system of a projection television receiver for projecting pictures from a picture tube onto a screen, comprising a fluorescent face constituting the tube face of the receiver tube having a nonspherical shape in such a direction as to compensate the curve of the image face of the projected picture on the screen, and further comprising lenses arranged from the screen side to the tube face of the picture tube in the order of:

Lens system for projection television receivers

In a projection system wherein an optical system comprising a first lens for correcting a spherical aberration dependent on the aperture length, a second lens for enlargement and a third lens for correcting a field curvature, projects an image reproduced on a CRT having a curved phosphor surface, onto a screen, the third lens is spaced from the CRT so that the region of the phosphor surface which again totally reflects a light which has been totally reflected by a screen-side surface of the third lens is limited to the edge portion of an effective region of the phosphor surface.

Projection lens system

A projection system comprising from the image end a screen, a lens in which a core portion including the lens axis accomplishes a convergence function and in which a peripheral portion including a lens edge thereof accomplishes the divergence function, a convex lens element, a concave lens element and a CRT having a face glass whose inner surface is coated with a phosphor and is so curved to form a fourth lens element with a curvature center within a core portion including the lens axis is disposed on the screen side of the projection system, the curvature radius of each part of the core portion of the fourth lens increasing thereof in accordance with increments of the semi-aperture distance of each part from the lens axis.

Projection system with a cathode ray tube and a lens

A lens system for a projection type television, having high focusing performance, a wide field angle and a reduced size. The lens system is composed of seven lenses, which are arranged successively from the screen side. The first lens, which is concave, and the second lens, which is convex, are cemented together to correct chromatic aberration. The third lens is a plastic lens for the correction of spherical aberration and astigmatism, at least one side of which is aspherical. The fourth lens, which is convex, and the fifth lens, which is concave, are cemented together to constitute an achromatic lens. In order to reduce the deterioration of focusing performance caused by changes in temperature, these two lenses are glass lenses and occupy the greater part of the power of the entire system. The sixth lens is an aspherical plastic lens for the correction of astigmatism and frame aberration, and the seventh lens is a plastic lens for the correction of image field curvature, using an aspherical surface.

Lens system for projection type television

The disclosure relates to a projector having an arrangement of polarizers and liquid crystal cells aligned on the axis of light in the order a first color polarizer colored in red, a first twisted nematic liquid crystal cell, a second twisted nematic liquid crystal cell, a second color polarizer colored in a green, a third twisted nematic liquid, a neutral polarizer and Guest-Host type colored in blue. Since, according to this, a polarizer having inferior color characteristics can be replaced by a Guest-Host type liquid crystal cell, the excitation purity and the scope of color reproduction are improved. Further, since the mixture of color is additive, the brightness of the reproduced color is also much improved.

Projector using guest-host liquid crystal cells for improved color purity

An improved lens system for a projection television is described. The lens system is designed to be used with a cathode ray tube having a face glass with an aspheric surface having phosphor elements mounted thereto. The aspheric surface of the face glass has its maximum radius at the optical axis and is of lesser radius outwardly thereof. From the screen, the lens system companies a first aspheric lens of relatively weak power, a second biconvex lens of relatively high positive power, a third aspheric lens of weak positive power and a fourth lens having a concave face on its screen sider and of relatively large negative power.

Lens system for a cathode ray tube projection system

A projection lens for magnifying an image displayed on a cathode-ray tube and projecting the magnified image on a projection screen comprises a first lens having a substantially plano surface opposite to the cathode-ray tube and a concave surface, a second lens which is convex meniscus lens having a concave surface opposite to the concave surface of the first lens, a third lens having a strongest positive refracting power and at one convex surface, and a fourth lens spaced apart by a predetermined distance from the third lens having at least one convex surface. The first to fourth lenses are arranged in the above order from the side of the cathode-ray tube, and the predetermined distance between the third and fourth lenses is large enough to permit interposition of a plano reflecting mirror therebetween.

Projection lens for projection television

An improved in-line type electromagnetic focusing cathode-ray tube which comprises magnetic yokes, a focusing magnetic field generating permanent magnet, a deflecting magnetic field control element and a cup-shaped spacer member for separating the magnetic yokes from the deflecting magnetic field control element. The deflecting magnetic field control element is disposed at a distance l.gtoreq.0.26 D from an end of the magnetic yoke closest to a fluorescent screen, where D is an outer diameter of the magnetic yoke, so that a beam spot on the fluorescent screen has substantially circular shape to attain an excellent focusing characteristic.

Growing community of inventors

Fujisawa, Japan

Kyohei Fukuda