Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Yasunori Kanazawa

Shinichi Abe

Nobuyuki Fujimoto

Tadahiro Kuwa

Yoshiyuki Nakamori

Takao Arai

Keizo Nishimura

Hiroyuki Kimura

Hitoshi Watanabe

Takaharu Noguchi

Kazuo Shigematsu

Yoshito Tsunoda

Seiji Yonezawa

Toshiaki Tsuyoshi

Wasao Takasugi

Toshinori Sugiyama

Masuo Umemoto

Shigeru Yamazaki

Norio Yokozawa

Akito Sakemoto

Seiichi Matsushima

Kenichi Kitta

Kouichi Tomatsuri

Haruo Arai

Tetsurou Ikegaki

Yoshiro Otomo

Mitsuyoshi Koyama

An optical information recording/reproducing apparatus includes signal recording means for recording a signal on a film. The signal is recorded by raising the temperature of the film with a writing laser beam. A signal reproduction apparatus reproduces the signal by irradiating the film with a reading laser beam. There is an optical system provided in common to both the writing laser beam and the reading laser beam. The signal recorded on the film is reproduced substantially simultaneously with the recording of the signal in order to allow for confirmation of the signal that has been recorded. A modulating circuit is provided for modulating the intensity of the writing laser beam with a frequency of at least twice as high as the maximum frequency of the signal to be recorded.

Optical information recording/reproducing apparatus

A recording disc cartridge comprising a disc case formed by a top half and a bottom half each having a spindle hole and a head insertion hole, a recording medium rotatably enclosed in the disc case, shutter means for closing and opening the spindle holes and the head insertion holes, a slide means for moving the shutter means in both lateral directions relative to a line which passes through each center of the spindle hole and the head insertion hole and means for resiliently exerting the slide means so as to drive the shutter means for closing the spindle holes and the head insertion holes.

Shutter assembled disc cartridge

A disc cartridge having a case, a disc contained in the case, a shutter mechanism for opening and closing a head insertion window and drive shaft insertion hole and a disc clamping mechanism for clamping the disc when the disc is not in use, the disc clamping mechanism functionally entirely independent of the movement of the shutter mechanism.

Disc cartridge

A disc cartridge comprising a cartridge case, a magnetic recording disc rotatably mounted in the cartridge case, and head insertion openings formed extending to the side portions of the cartridge case, the openings being opened even at one edge of the cartridge case for facilitating insertion of the head mounted in a recording and play back device, the cartridge case being reinforced by at least one reinforcement member having a smaller diameter or a smaller thickness than the thickness of the cartridge case.

An information recording disc is provided with a magnetic attracting member in the form of metal piece or magnetic material which serves for attracting a disc member for recording, in particular, for optical recording and reproducing of information, to a spindle of a recording and reproducing apparatus. The magnetic attracting member is held in the space of a holder which is fixedly secured to the disc without the magnetic attracting member being fixedly secured to the disc. This arrangement enables a magnetic clamping of the disc member which provides for a decrease of retardation and is suitable for miniaturization of the apparatus.

Information recording disc

A record carrier has a circular disc-shaped substrate on which a recording layer capable of optically writing information therein is disposed, and is so constructed that a plurality of circumferential reference tracks extending in a rotating direction are provided at radial intervals, the reference track being put into an optically detectable structure so as to function as an optical guide for recording information between the adjacent reference tracks. A first light beam and a second light beam are condensed by an identical objective lens so as to be respectively focused on the recording layer of the record carrier. As one of the reference tracks is being tracked by the first light beam, the second light beam is diffracted by a light diffracter so as to be spaced from the first light beam on the record carrier by desired track pitches in the radial direction thereof. Thus, data is sequentially recorded at predetermined pitches in a recording area located between the reference tracks by means of the second light beam.

Apparatus and record carrier for optically writing information

A color sensor includes a plurality of light emitting sources of different colors each of which is driven in a time divisional manner to emit the different colors sequentially, a light receiving element for receiving the light from an object illuminated by the respective color lights from the light emitting sources and a circuit arrangement for producing output signals representing the color of the object.

Color sensor

An azimuthal magnetic recording and reproducing apparatus comprises a magnetic head including at least one head gap for the recording and reproduction of information on and from recording tracks extending in the longitudinal direction of a magnetic tape. In the apparatus, the head gap is disposed to make the recording and reproducing operation so that the direction of magnetization on one of the recording tracks differs from that on the adjacent one.

Azimuthal magnetic recording and reproducing apparatus

A circuit for reproducing and demodulating a modulated digital signal which is modulated in a predetermined modulation system such as MFM, EFM and so on. A phase of a clock having a frequency multiplied by an integral number of a bit frequency of the modulated digital signal, is restricted or controlled by a signal showing that a predetermined pattern of the modulated digital signal occurred. The modulated digital signal is demodulated by the thus restricted clock to produce digital informations '0' and '1'. A main requirement for detecting the predetermined pattern of the modulated digital signal, is that a reproduced modulated digital signal is reliable. In order to compensate for the drop-out of the modulated digital signal, the demodulation circuit is provided with a modulated digital signal reproducing circuit for complementing a predetermined signal pattern when the drop-out occurred.

Circuit for reproducing and demodulating modulated digital signals

A PCM recording system uses vertical and horizontal synchronizing signals like those of a television video signal, and records PCM sound signal data taking the form of PCM signals converted from a sound signal during specific ones of plural horizontal scanning periods disposed between the vertical synchronizing signals. At least one control signal such as an absolute address signal representing a tape position, an operation indicating signal for indicating the operations such as a tape running stop and a tape rewind and an adjusting signal for adjusting a reproducing system is recorded during the horizontal scanning period with no recording of the PCM sound signal data. At the time of signal reproducing, the control signal is extracted to perform a given display or a given control.

Automatic operation control apparatus for a PCM recording and

When error detection codes are added to a sampled signal word which is a digital version of audio information and a control signal which is a digital version of system control information to construct a data frame and a control signal frame, respectively, the error detection code for the data frame is generated under an arithmetic condition different from that for the control signal frame. In this manner, frame identification information is superimposed on the error detection codes. In a reproducing unit, the error detection codes containing the identification information are used to check an error in the reproduced sampled signal word and control signal and to effect the discrimination between the data frame and the control signal frame.

PCM Recording and reproducing apparatus

A PCM recording apparatus is disclosed in which digitized left and right channel sample signals each having error detecting bits and a signal indicative of a correlation such as sum or difference of the two samples are recorded on a record medium in a predetermined arrangement, and an error in coding is detected from the correlation signal.

PCM Recording apparatus

A PCM recording and reproducing apparatus comprising an error detecting circuit for detecting a frame including at least one word information signal with an error, the frame being a reproduction signal read from a recording medium on which certain pulse coded information is recorded in a frame distribution system, and a compensating circuit for compensating the reproduced information signal by the use of the output signal from the error detecting circuit, thereby removing the adverse effects of information dropout in spite of a high density recording.

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Hachioji, Japan

Yasunori Kanazawa