Abstract: A magnetic or optical disc device which can correctly follow the eccentricity of an eccentrically chucked disk and which can immediately follow the eccentricity of the new disk face when there is a changeover of the disc being accessed operates with a disc having data tracks provided with uniformly spaced clock marks for providing a timing standard and includes a reproduction circuit for reproducing data from the disc, a clock sampling circuit for extracting a first clock signal output by the reproduction circuit, an eccentricity magnitude memory section for storing a signal corresponding to the eccentricity of the data tracks with respect to the axis of rotation of the disc; a clock correction section.

Abstract: An optical disc, an apparatus and a method for recording/reproducing the optical disk use Gray coded address information. The hexadecimal data 0 to F correspond to the Gray codes. The Gray code consists of the upper address and the lower address. The four channels of the upper address and the four channels of the lower address are set so that one channel of each address is "1". With the change of the data from 0 to F, the channel of "1", in the lower address sequentially moves to the adjacent channel in the corresponding Gray code. Consequently, rapid seeking can be performed by detecting only the lower address.

Abstract: An optical disc having address information recorded in a wobbling manner is arranged to record or reproduce data at correct positions. A track is previously formed as a pregroove and is wobbled in accordance with address information. The track is divided into a plurality of sectors. A plurality of sync marks S are formed in each sector, and at least one of the sync marks in one round of the track is formed as a reference mark R different from the other sync marks S. To reduce overhead and to achieve highdensity random recording and reproduction, a method may also be used in which one cluster of data is formed of a data area and a link area located between data areas and consisting of two frames, in which each of the data area and the link area has a structure formed of unit frames separated by a sync signal (frame sync), and in which data is recorded or reproduced as unit clusters.

Abstract: An optical disc having address information recorded in a wobbling manner is arranged to record or reproduce data at correct positions. The optical disc includes at least one track on which data is recorded and which is previously formed as a pregroove wobbled in accordance with an address information, where the track has a plurality of frames wobbled in accordance with the address information, and further where a plurality of sync marks is formed in each of said frames by wobbling said pregroove at a center frequency of frequencies of wobbling with the address information.

Abstract: An information recording and reproducing apparatus and an information storage disc for use therewith. The information storage disc has ID storage areas formed in predetermined locations in the radial direction of the disc, the ID storage areas storing either sector or track numbers previously and magnetically. In this setup, if the read head is dislodged from the center line of a given track, the read head still reads the sector number correctly. The information recording and reproducing apparatus has the read head and the write head arranged so that they are positioned on a given intermediate track in a substantially aligned manner. With the write head positioned on a given track, the read head is dislodged from that track only by a negligible distance. This allows the read head to read sector and track numbers unfailingly from the disc.

Abstract: An optical dick, an apparatus and a method for recording/reproducing the optical disk use Gray coded address information. The hexadecimal data 0 to F correspond to the Gray codes. The Gray code consists of the upper address and the lower address. The four channels of the upper address and the four channels of the lower address are set so that one channel of each address is "1". With the change of the data from 0 to F, the channel of "1" in the lower address sequentially moves to the adjacent channel in the corresponding Gray code. Consequently, rapid seeking can be performed by detecting only the lower address.

Abstract: An optical disc having address information recorded in a wobbling manner is arranged to record or reproduce data at correct positions. A track is previously formed as a pregroove and is wobbled in accordance with address information. The track is divided into a plurality of sectors. A plurality of sync marks S are formed in each sector, and at least one of the sync marks in one round of the track is formed as a reference mark R different from the other sync marks S. To reduce overhead and to achieve high-density random recording and reproduction, a method may also be used in which one cluster of data is formed of a data area and a link area located between data areas and consisting of two frames, in which each of the data area and the link area has a structure formed of unit frames separated by a sync signal (frame sync), and in which data is recorded or reproduced as unit clusters.

Abstract: An optical disc having address information recorded in a wobbling manner is arranged to record or reproduce data at correct positions. The optical disc includes at least one track on which data is recorded and which is previously formed as a pregroove wobbled in accordance with an address information, where the track has a plurality of frames wobbled in accordance with the address information, and further where a plurality of sync marks is formed in each of said frames by wobbling said pregroove at a center frequency of frequencies of wobbling with the address information.

Abstract: A data recording region of a disc is divided into a plurality of zones, the plurality of zones comprising a plurality of bands, and with a range from an innermost radius to an outermost radius being divided into four bands by four radii, with the rotational velocity of the disc at each of the bands being fixed in such a manner as to increase disc capacity.

Abstract: An optical disk, an apparatus and a method for recording/reproducing the optical disk use Gray coded address information. The hexadecimal data 0 to F correspond to the Gray codes. The Gray code consists of the upper address and the lower address. The four channels of the upper address and the four channels of the lower address are set so that one channel of each address is "1". With the change of the data from 0 to F, the channel of "1" in the lower address sequentially moves to the adjacent channel in the corresponding Gray code. Consequently, rapid seeking can be performed by detecting only the lower address.

Abstract: A magnetic or optical disc device that can correctly follow the eccentricity of an eccentrically chucked disc operates with a disc having data tracks provided with uniformly spaced clock marks for providing a timing standard and includes a reproduction head mounted on a turnable arm arranged for movement relative to the disc and a head traveling radial position detector attached to the arm that detects the rotational angle and produces a head position signal. A home index signal is detected and used along with the radial position signal and a derived clock signal to measure eccentricity magnitude that is stored in a memory and subsequently accessed for use in generating a control signal for a phase lock loop that provides an eccentricity adjusted clock signal.

Abstract: A magnetic or optical disc device which can correctly follow the eccentricity of an eccentrically chucked disk and which can immediately follow the eccentricity of the new disk face when there is a changeover of the disc being accessed operates with a disc having data tracks provided with uniformly spaced clock marks for providing a timing standard and includes a reproduction circuit for reproducing data from the disc, a clock sampling circuit for extracting a first clock signal output by the reproduction circuit, an eccentricity magnitude memory section for storing a signal corresponding to the eccentricity of the data tracks with respect to the axis of rotation of the disc; a clock correction section.

Abstract: Clock marks for sampling clock components have been formed in advance at constant intervals along the tracks of a disk recording medium and, when rotationally driving the disk recording medium, these clock marks are detected to sample clock components. By sampling the clock component from the clock marks thus formed at fixed periods and further generating an interpolation clock in a region between the clock marks on the basis of the sampled clock component, a very accurate clock can be obtained, as compared to the case in which a clock is sampled from reproducing code. Consequently, there can be realized a further large-capacity disk recording medium.

Abstract: A magnetic disk is provided with a track divided by servo areas to record servo signals and data areas to record data signals. Within the servo area, an exclusive region is previously formed to specifically record the servo signal. In one embodiment, the servo region is formed along the moving locus of a magnetic head while writing and reading data, which extends both along the radial direction and peripheral direction of the magnetic disk.

Abstract: In a head displacement measuring method, prior to actual data recording or data reproduction, either one of the recording head and the reproducing head is wobbled, and the test data is recorded in the disk-shaped recording medium by the recording head. Then, the test data is reproduced from the test data by the reproducing head, and displacement between the recording head and the reproducing head is detected on the basis of the reproduced test data. Thus, the displacement may be detected more easily with higher precision than with the conventional optical detecting method.

Abstract: A disc recording/reproducing apparatus includes a tracking servo system in which a recording/reproducing head is moved based upon a target position signal indicating its pre-set target position on a disc-shaped recording medium and in which the recording/reproducing head is controlled in its position by a driving unit which employs an output of a controller which is supplied with a position signal obtained by subtracting a deviation from a pre-set target position from the target position signal. The apparatus also includes an eccentricity data storage unit for storing eccentricity data indicating the tracking position of the recording/reproducing head which depends upon eccentricity of the disc-shaped recording medium. The eccentricity data from the eccentricity data storage unit is summed to the target position signal for controlling the position of the recording/reproducing head.

Abstract: A magnetic or optical disc device which can correctly follow the eccentricity of an eccentrically chucked disk and Which can immediately follow the eccentricity of the new disk face when there is a changeover of the disc being accessed operates with a disc having data tracks provided with uniformly spaced clock marks for providing a timing standard and includes a reproduction circuit for reproducing data from the disc, a clock sampling circuit for extracting a first clock signal output by the reproduciton circuit, an eccentricity magnitude memory section for storing a signal corresponding to the eccentricity of the data tracks with respect to the axis of rotation of the disc; a clock correction section.

Abstract: A clock signal generating apparatus and method in which data recorded in a plurality of tracks and clock marks recorded at equal angular spaces at different radial distances on a rotating disk are reproduced by a reproducing head from the disk and a clock signal is generated in synchronism with the clock marks reproduced by the reproducing head by means of a discriminating circuit for detecting a synchronous state between the generated clock signal and the reproduced clock marks, a circuit for causing oscillation of the reproducing head in a radial direction of the disk over a plurality of tracks when the synchronous state discriminating circuit determines that the clock signal is not synchronous with the clock marks, and a phase-locked loop circuit for generating the clock signal in synchronism with the clock marks reproduced from the disk while the reproducing head is oscillated over the plurality of tracks by synchronizing on the clock marks reproduced at a variety of different radial positions on the disk

Abstract: A data pattern generator generates pattern data corresponding to a pre-formatted data pattern and supplies the pattern data to a disc-like recording medium producing apparatus for forming the pre-formatted data pattern, such as clock information, servo information and read-out information in a disc-like recording medium. The data pattern generator includes a first memory unit for storing therein as a data array at least part of a data pattern formed on a disc-like recording medium, and a second memory unit for storing therein an order for outputting the data array or a coordinate for outputting the data array. The data array is re-arrayed in accordance with an angle of rotation of the disc-like recording medium and then is output.

Abstract: An offset amount measuring apparatus for measuring an offset amount resulting from an offset produced when a disk, which is provided with a plurality of clock mark signals recorded around each circular data track at physically regular intervals, is mounted by chucking on a disk apparatus, reading the clock mark signals from the circular data track with a head, is disclosed.