Matsushita Electric Industrial Co., Ltd.

Osamu Yamaguchi

Yoshihiro Kanda

Yoshiho Gotoh

Hiroyuki Yamaguchi

Mitsurou Moriya

Hiroshi Okamoto

Souichirou Fujioka

Masafumi Nishida

Yoshihisa Fukushima

Hiromichi Ishibashi

Mitsuro Moriya

Namio Hirose

Shinichi Yamada

Shin-ichi Yamada

Yasuki Matsumoto

Toshiyuki Kinou

A torque command supplied to a tape running unit for drawing out and driving a tape wound on a first reel is modulated by a torque modulator depending on a moment of inertia of the first reel, a winding radius of the tape wound on the first reel, a moment of inertia and a rotating radius of the tape running unit, which are detected by a parameter detector. The first motor is responsive to the modulated torque command for rotating the first reel, thereby keeping the tension of the tape constant.

Magnetic tape tension control device

An optical information recording medium includes a track storing information in a plurality of sectors, wherein the track is formed spirally or concentrically. One sector includes a plurality of frames and one frame includes a resync mark region, a frame address region, an information region, and a postamble region. In the information region in the first frame, identification information for identifying the position of the sector is stored. In the information region in each frame, information obtained as a result of scrambling performed based on a value of the identification information is stored.

Optical information recording medium, optical information recording

An apparatus for outputting a tracking error signal based on the time change in the intensity distribution of a laser beam diffracted by the data pits is provided for an optical reproduction system using an optical record carrier on which data is recorded with a high recording density. The photodetector is divided orthogonally into four parts, and boost filters having identical characteristics are disposed for the output signal of one pair of diagonally located photodetector elements and for the output signal of the other pair of diagonally located photodetector elements. The detection gain of the short mark reproduction signal can thus be increased above the detection gain of the long mark reproduction signal to prevent the loss of short marks and improve the S/N ratio of the tracking error signal.

Tracking error signal detector

A focusing control apparatus is provided for controlling focusing of a light beam on a recording medium. The apparatus includes a control mechanism for maintaining the focusing state of the light beam on the recording medium by moving a focus mechanism based on a comparison between an output signal indicative of the focusing state and a target value. The apparatus further includes a target value setting circuit for setting the target value at a first level when the light beam is irradiated on the land track portions of the recording medium; and for setting the target value at a second level when the light beam is irradiated on the groove track portions.

Focusing control apparatus using dynamic target value in relation to

An optical information reproduction apparatus for reproducing information from a disc having a plurality of tracks storing the information in the form of pits includes a radiation device for radiating a light beam toward the disc to form a light spot on the disc; a moving device for moving the radiation device to move the light spot in a direction crossing the plurality of tracks in a radial direction of the disc; a photodetector having a detecting plane for receiving the light beam reflected by the disc, the detecting plane being divided into four detection areas at least in a direction parallel to a tangent of the tracks and in a direction perpendicular to the tangent of the tracks, the four detection areas generating light intensity signals corresponding to the intensities of the light beam which is received; a positional offset detector for detecting a positional offset of the light spot with respect to one of the tracks based on the light intensity signals generated by the photodetector and outputting the detection result as a positional offset signal; a signal processor for performing processing of the light intensity signals including logic operation to obtain an operation signal; and a direction detector for detecting a direction in which the light spot moves with respect to a target track based on the positional offset signal and the operation signal during the movement of the light spot toward the target track.

Method for detecting the movement of a light beam and optical

A tape speed command signal is differentiated, and in a multiplier, the torque necessary for acceleration or deceleration of a take-up reel motor is calculated in accordance with the moment of inertia of a take-up reel and a winding radius of the tape on the take-up reel. The calculated result is added to a torque command produced by a feedback control system.

Tape speed control apparatus using rotation speed ratio of first and

A torque command is applied to a tape running unit. The tape running unit for draws out and drives a tape wound on a first reel and taken up on a second reel. The torque command is modulated by a torque modulator in accordance with a moment of inertia of the first reel, a winding radius of the tape wound on the first reel, a moment of inertia of the second reel and a rotating radius of the second reel, which are detected by a parameter detector. The first motor is responsive to the modulated torque command for rotating the first reel, thereby keeping the tension of the tape constant.

In a tracking control apparatus of a recording and reproducing apparatus for an optical disk, information is recorded in groove tracks and land tracks of the optical disk and address information is recorded in an address area arranged to each of the groove tracks and the land tracks, a control signal corresponding to a positional deviation between a light beam spot and a track is derived on the basis of light reflected from the optical disk, and hence an address period in which the light beam spot traces the address area is derived. When the light beam spot traces the land track, a tracking operation is performed by a control signal which is invert in polarity to that of groove track, and when the light beam spot traces the address area, the tracking control is performed by a signal of the same polarity as that of the groove track.

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Hirakata, Japan

Osamu Yamaguchi