Hitachi, Ltd.

Fukuyasu Abe

Nobuyuki Kaku

Satoshi Ouchi

Taro Imahase

Kenmei Masuda

Tomohiro Miyoshi

Nobuo Masuoka

Tatsuo Morita

Mikio Shiraishi

Kenji Fuse

Atsushi Inoue

Shigemitsu Higuchi

Hidekazu Takeda

Yoshiharu Yamashita

Shinya Fujimori

Shigeyuki Kobata

Kenji Ogiro

Taichiro Yamashita

Takao Terayama

Tomomi Okamoto

Kazuo Sakai

Fumio Takeda

Fujio Tajima

Takayuki Munemoto

Kazuyuki Kodama

Tomokazu Ishii

Kuniaki Hirayama

Kooetsu Okuyama

Toshihiko Imachi

Yoshio Uemura

Hisashi Ichikawa

Masahiko Fujishiro

Masashi Ueda

An image display device includes a light source which outputs a first light including a first color light, a second color light and a third color light, a polarity converter which unifies polarities of the first light into a single polarity, a dichroic mirror which separates the first color light from the first light which is output by the polarity converter, and first to third reflective liquid crystal display elements, respectively, installed for the first to third color lights. First to third polarized beam splitters are provided together with first and second wavelength selective polarity rotator elements. A projection lens is provided so as to project a light combined by the third polarized beam splitter, and the first color light, which is reflected by the first reflective liquid crystal display element, permeates the first polarized beam splitter and the third polarized beam splitter.

Image display device

An image display device has three reflective image display elements for red, green and blue to form an optical image according to a video signal from light output from a light source, and an optical system to supply light onto the display elements and to combine and output the light reflected from the display elements. The image display device includes a first polarity converting unit to convert luminous flux from the light source to S polarized light, a first polarized beam splitter, and second polarized beam splitter. The reflective image display element for green is provided in a vicinity of the first polarized beam splitter, and the light reflected by the first polarized beam splitter and input to the reflective image display element for green is S polarized light. The light output from the reflective image display element for green permeates the first and second polarized beam splitters.

A projective display apparatus having an illumination unit which includes a light source, an integrator lens and a collimator lens, a light splitter unit which splits light beams from the illumination unit into a plurality of color components, a plurality of light valves, a cooling fan, and a wind guiding unit. A respective one of the light valves corresponds to a respective one of the color components. The wind guiding unit guides the cooling wind from the cooling fan to the illumination unit and the light valves. The wind guiding unit splits and forms at least two branch wind guiding paths. One of the branch wind guiding paths guides cooling wind from the cooling fan to the illumination unit and another of the branch wind guiding paths guides the cooling wind to the light valves.

Display optical unit and display apparatus using this unit

A compact, lightweight, low cost image display device with high image quality and improved brightness are attained by a combination of a color separating means and color separating/combining means and color combinations means and two reflecting means and polarizing plate to change the polarization direction of the light and a polarized beam splitter on the optical axis of reflective liquid crystal display element.

A display optical unit includes a light valve which modulates light to form picture information, a light splitter which splits light into a plurality of color components and for directing each of the color components to the light valve, an illumination unit which directs light emanated from a light source to the light splitter, and a projection lens which magnifies and projects the modulated light having the picture information for displaying a picture. An optical axis of the projection lens is shifted from an optical axis of the illumination unit and the light splitter, and a projection lens unit including the light valve and the projection lens has a positioning mechanism which determines a position thereof when attached and is attachable and detachable in a direction perpendicular to an optical axis of the projection lens unit.

A display optical unit and apparatus in which the optical axis of a projection lens is shifted from the optical axis of an illumination unit and light splitter. The projection lens is attachable and detachable in a direction in which the optical axes are shifted from each other. A light valve or a polarizer is cooled by cooling winds blown by a cooling device to the light valve or polarizer through a plurality of wind supply openings are arranged in directions different from one another and within the range of 45 degrees to 315 degrees so as to enable cooling of the display optical unit.

Display optical unit and display apparatus

A drum base according to he invention, on which a drum of a magnetic tape recorder is mounted, comprises a substantially annular frame having a fixing surface to which the drum is fixed; at least one through hole extending through the fixing surface for allowing a screw which is to be threadably attached to a threaded hole formed in the drum to pass therethrough; and a pair of mounting surfaces provided on the fixing surface on which the drum is mounted, the mounting surfaces being located adjacent to the at least one through hole so as to have a symmetrical relationship in a circumferential direction of the annular frame with respect to the at least one through hole and within a range of a diameter dimension of the at least one through hole in a radial direction of the annular frame.

Drum base on which a drum of a magnetic tape recorder is mounted

Disclosed in an arrangement to achieve satisfactory head contact by increasing contact face pressure at a head gap and to reduce the change in time of head contact performance in a double azimuth head. Heads in a portion in which a tape is slid are respectively constructed with each head having two different arcs with a radius of curvature R1 in a first area which includes a gap, and with a radius of curvature R2 in a second area which is adjacent to the first area. A transition portion P for transitioning an arc with the radius of curvature R1 and an arc with the radius of curvature R2 is located in the direction of its adjacent head based upon a contact point Q on R1 of a common tangent drawn from an arc forming a periphery of a rotating drum to a circle formed by R1. The relationship between the radiuses of curvature in two areas is set to R1&gt;R2. As the area in which a tape is in contact can be reduced, contact face pressure by the tape on a gap can be increased, satisfactory head contact can be obtained and as a contact area with a tape is wide to some extent, a change in time of contact performance can be reduced.

Rotary head and recording/reading apparatus provided with rotary head

As a method of increasing the storage capacity of a magnetic recording and reproducing apparatus for recording and reproducing information to and from a magnetic tape in a cartridge, there is a helical scan recording method in which the magnetic tape is diagonally wound around a drum which rotates a magnetic head. With an apparatus adapted to this method, the disposition of the cartridge and the take-up reel for taking up the magnetic tape on the same plane arises a necessity of considerably bending the magnetic tape at the drum portion and, accordingly, the magnetic tape is damaged. In order to prevent the damage of the foregoing type, the tape passage surface from the cartridge to the drum and the tape passage from the drum to the take-up reel are formed by an angle at which the direction in which the magnetic tape is moved is changed due to winding of the magnetic tape around the drum so that the magnetic tape is not bent excessively. A threading device capable of three-dimensionally controlling the position of the magnetic tape in accordance with a predetermined tape passage is provided for the apparatus structured as described above. The threading device is formed by a link mechanism to be moved along the locus of a cam groove so that the three-dimensional position control can be performed.

Magnetic recording and reproducing apparatus

A recording/playback apparatus including a stationary drum on which a traveling magnetic tape is wound, a plurality of magnetic heads for recording and playing back data, a rotary portion which is rotated while carrying the heads thereon, a drive portion which drives the rotary portion, an air injection device which spouts air from the vicinities of the magnetic heads toward the magnetic tape in order to separate the tape from the heads, and a control device which controls the start and stop of the air spouting of the air injection device. In the standby mode of the apparatus, in which the rotary portion is rotated though the heads perform neither the recording nor the playback operation, the tape is separated from the heads, so that the heads are prevented from wearing away. As soon as the standby mode has ended, the tape is brought into contact with the heads, so that the recording or playback operation can be immediately started.

Recording/playback apparatus for controlling contact between a head and

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Yokohama, Japan

Fukuyasu Abe