Nippon Telegraph and Telephone Corporation

Fujitsu Corporation

Nippon Telegraph & Telephone Co.

Kikuji Katoh

Shigenori Yanagi

Manabu Yamamoto

Takaya Tanabe

Hisanobu Dobashi

Nobuyoshi Izawa

Makoto Takayanagi

Kazuki Kudo

Yoshihiro Isomura

Yoshihiro Sako

A media library system capable of carrying out an access to each recording medium in very short time. A media exchange operation is controlled such that the storage cells of the storehouse are divided into at least two groups arranged in an order of average distances with respect to the media drive, including a first group with a shortest average distance with respect to the media drive, and when the previously used recording medium was mounted on the media drive from the first group, the previously used recording medium is stored in the first group, whereas when the previously used recording medium was mounted on the media drive from one group other than the first group, one recording medium with a lowest utilization frequency among an adjacent group of that one group having a shorter average distance with respect to the media drive than that one group is moved from that adjacent group to that one group and then the previously used recording medium is stored in that adjacent group.

Media library system using media management scheme for reducing

The purpose of the present invention is to provide a method and an apparatus for seeking-control for disk drives, in which (i) the step current waveform at the start of speedup or at the switching from speedup to slowdown is transformed into a current waveform by which the mechanical resonance of the disk drive is difficult to be excited; (ii) the lowering of tracking accuracy is prevented; and (iii) the effective seek time being measured from the seek start up to the time at which the writing or reading of the disk becomes possible can be shortened. The seeking control apparatus for disk drives according to the present invention comprises a reference velocity generator for generating a reference velocity which is defined as a function of the number of residual tracks; a subtracter for detecting a velocity difference between a moving velocity of a read-write device of a disk drive to be controlled and the reference velocity, and outputting the detected difference; a proportional amplifier for amplifying the output from the subtracter; a slew-rate limiter for limiting a rate of change of the control output from the proportional amplifier lower than a predetermined level, and outputting a limited output; and a power amplifier for amplifying the output from the slew-rate limiter and outputting positioner current.

Seeking control apparatus and method for disk drives, using slew-rate

The present invention provides a data readout apparatus and method using optical beams by which high data-recording density for optical recording media and high transfer rate for regenerated data can be realized. The data readout method of the present invention comprises the steps of: making a first optical beam incident on an optical recording medium in a manner such that in three successive tracks n-1, n, and n+1, n being an integer of two or more, on the recording medium, the center of the beam spot of the first optical beam lies, in a transverse direction of the tracks, between the boundary point of tracks n-1 and n and the center of track n-1; making a second optical beam incident on the optical recording medium in a manner such that the center of the beam spot of the second optical beam lies, in the transverse direction of the tracks, between the boundary point of tracks n+1 and n and the center of track n+1; detecting reflected beams of the first and second optical beams from the optical recording medium; and regenerating data recorded on the three tracks in accordance with levels of the detected reflected beams. According to this, data sequences recorded on three successive tracks can be regenerated simultaneously by using two optical beams; thus, even if the track pitch is narrowed, it is possible to detect signals without the influence of crosstalk, and the data transfer rate can be increased. The apparatus for implementing this method allows simpler circuit arrangement.

Optical data readout with two beams on three tracks

This invention enables one, or both, or none of position servo control and position lock control of a galvanomirror, to control a read beam to an optimum position under any of on-track state, seek state, position setting state after the completion of a seek operation, and positional deviation existing state between a write beam and the read beam. The invention locks the position of the galvanomirror when a unit is energized or retried, reads a galvanomirror position signal provided at this moment, finds an offset signal for zeroing the galvanomirror position signal, and adds the offset to the position locked galvanomirror during a seek operation with the write beam, thereby removing an offset of the galvanomirror position signal. The invention determines that the galvanomirror has been abnormally deflected due to a malfunction of a tracking control servo system, upon detecting an abnormality that a tracking error signal used for the tracking control of the read beam exceeds a threshold value and an abnormality that a galvanomirror position signal used for locking the galvanomirror at a central position exceeds a threshold value. The invention removes an offset by adding the galvanomirror position signal to the tracking error signal of the read beam. It is possible to add a lens position signal as well to remove the offset. (FIG. 1B)

Beam position control system of an optical disk unit

A seek control system is used for a magneto-optic disk unit which has an optical head driven by a VCM positioner, two lens actuators disposed on the optical head, and respective object lenses disposed on the lens actuators for passing first and second beams (erase and write beams) to irradiate an identical track on a medium thereby to record and reproduce data thereto and therefrom. To shorten an access time needed for accessing a target track through a lens seek operation carried out by driving the two lens actuators and to prevent a deviation (off-track) of the second beam from the target track during the VCM positioner seek operation according to the first beam and shorten an access time, upon receiving a seek instruction from a higher device respective, exclusive use processors carry out the lens seek control of the first and second beams, in parallel. The number of tracks respectively crossed the first and second beams are counted so that, when the moving speed of the second beam decreases to a lens seek possible speed at a specified target track due to the positioner seek operation with the first beam, the lens seek operation with the second beam is started.

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Tokorozawa, Japan

Kikuji Katoh