Optical disk drive

Claim 2

An optical disk, having thereon: at least one circular track on which desired information is recorded, reproduced or erased by a light beam projected as a spot, one complete turn of the track representing one track line; at least one uninterrupted preformed groove adjoining the track, the preformed groove being used for tracking of the spot of the light beam and for detecting the number of track lines crossed by the spot when the spot is moved to a desired position, and index marks providing reference positions for recording of address information indicating locations on the optical disk, the address information being used to record the desired information, the index marks being formed by partial variations in the preformed groove in a radial direction of the optical disk.

Claim 3

An optical disk, having thereon: a pre-format area where specific information is prerecorded; and a soft-format area where desired information is able to be recorded, reproduced or erased, wherein the pre-format area comprises at least one preformed groove that is used for tracking of a spot of a light beam when reproducing the specific information, the preformed groove having no interruptions in a circular direction of the optical disk, and address marks containing address information indicating locations on the optical disk, the address marks being preformed by variations in the preformed groove in a radial direction of the optical disk, and wherein the soft-format area comprises at least one circular track on which desired information is recorded, reproduced, or erased with the spot of the light beam, one complete turn of the track representing one track line, one uninterrupted pre formed groove adjoining the track, the preformed groove being used for tracking of the spot of the light beam as well as detection of the number of track lines crossed by the spot of the light beam when the spot is moved to a desired position, and index marks providing reference positions for recording of the address information indicating locations on the optical disk, the address information being used in recording of the desired information, the index marks being formed by partial variations in the preformed groove in a radial direction of the optical disk.

Claim 4

The optical disk as defined in claim 1 or 3, wherein the range of the radial variations in the preformed groove is determined in accordance with a balance between an S/N ratio of the address information and the accuracy of detection of the number of track lines crossed by the spot of the light beam.

Claim 5

The optical disk as defined in any of claims 1, 2 and 3, wherein the track is a spiral track.

Claim 6

The optical disk as defined in any of claims 1, 2 and 3, wherein the track is a series of concentric tracks.

Claim 7

The optical disk as defined in claim 1, wherein the address information is recorded by wobbling the preformed groove in accordance with modulation data generated from the address information.

Claim 8

The optical disk as defined in claim 1, wherein the address information is recorded by varying a width of the preformed groove by means of a groove-width modulation in accordance with modulation data generated from the address information.

Claim 9

The optical disk as defined in claim 7 or 8, wherein the modulation data is generated by a biphase-mark modulation.

Claim 10

The optical disk as defined in claim 1, wherein the track is divided into a plurality of sectors, each sector comprising a header portion where the address information providing track and sector addresses is prerecorded, and a data portion where desired information is recorded, reproduced or erased, and wherein the preformed groove is varied in a radial direction of the optical disk in the header portions.

Claim 11

The optical disk as defined in claim 2 or 3, wherein one index mark is provided for each track line.

Claim 12

An optical disk drive, comprising: optical head means for projecting a light beam as a spot onto an optical disk; optical head driving means for moving the spot of the light beam to a desired track line on the optical disk, the track line representing one complete turn of a circular track on the optical disk; photodetector means for transmitting a detection signal by detecting a variation in intensity of reflected light from the spot of the light beam; hysteresis comparator means for generating a binary signal by comparing the detection signal from the photodetector means with a first slice level and with a second slice level when the spot of the light beam crosses the track line, the second slice level being higher than the first slice level; and counting means for receiving the binary signal from the hysteresis comparator means and for counting the number of track lines crossed by the spot of the light beam, wherein a level of the binary signal turns from high to low in accordance with the comparison between the detection signal and the first slice level, while it turns from low to high in accordance with the comparison between the detection signal and the second slice level.

Claim 13

The optical disk drive as defined in claim 12, wherein the optical disk drive satisfies the equation, Xt > Δy > Xs where Xt denotes an amplitude of the detection signal, Xs denotes an amount of amplitude distortion of the detection signal, and by denotes a difference between the second slice level and the first slice level.

Claim 14

An optical disk drive, comprising: optical head means for projecting a light beam as a spot onto an optical disk; photodetector means for detecting a variation in intensity of reflected light from the spot of the light beam and for transmitting a detection signal; index mark detecting means for detecting an index mark and for generating an index mark detection signal, one index mark being formed on each track line on the optical disk, the index mark being optically readable, one track line representing one complete turn of a circular track on the optical disk; optical head control means for moving the spot of the light beam to a desired track line in accordance with the detection signal; formatting means for generating formatting data of address information of track and sectors in accordance with the index mark detection signal, the address information being necessary for recording, reproduction and erasing of desired information; and recording means for recording the address information on the desired track line in accordance with the formatting data.

Claim 15

The optical disk drive as defined in claim 14, wherein the optical head control means comprises: counting means for counting the number of track lines crossed by the spot of the light beam; optical head driving means for moving the optical head means in a radial direction of the optical disk; comparator means for comparing numerated data of the counting means with a desired value; and driving signal generating means for supplying a driving signal to the optical head driving means until the numerated data coincides with the desired value.

Claim 16

The optical disk drive as defined in claim 14, wherein the recording means includes magnetic head means for applying a magnetic field onto the optical disk during magneto-optical recording.

Claim 18

The optical disk as defined in claim 2 or 3, wherein the range of the radial variations in the preformed groove is determined in accordance with a balance between an S/N ratio of an index mark detection signal that is generated by reproducing the index mark and the accuracy of detection of the number of track lines crossed by the spot of the light beam.

Claim 19

The optical disk as defined in claim 3, wherein the specific information is descriptions of a type of the optical disk and recording conditions.

Claim 20

The optical disk as defined in claim 3, wherein the specific information is an operating system.

Claim 21

The optical disk as defined in claim 3, wherein the specific information is a dictionary file.

Claim 22

The optical disk drive as defined in claim 14, further comprising: hysteresis comparator means for generating a binary signal by comparing the detection signal with a first slice level and with a second slice level, the second slice level being higher than the first slice level; and counting means for receiving the binary signal from the hysteresis comparator means and for counting the number of track lines crossed by the spot of the light beam, wherein a level of the binary signal turns from high to low in accordance with the comparison between the detection signal and the first slice level, while it turns from low to high in accordance with the comparison between the detection signal and the second slice level.

Claim 23

The optical disk drive as defined in claim 12, further comprising: comparator means which generates a binary address information signal by comparing the detection signal from the photodetector means with a reference level when the spot of the light beam is moved along the track; and demodulator means for demodulating the address information signal.

Claim 24

The optical disk drive as defined in claim 12, further comprising: polarized light splitter means for splitting the reflected light into first detection light and second detection light, polarization planes of the first detection light and second detection light being different from each other; first photodetector means for detecting a variation in intensity of the first detection light and for generating a first detection signal; second photodetector means for detecting a variation in intensity of the second detection light and for generating a second detection signal; adder means for adding the first detection signal and second detection signal; and subtractor means for calculating a difference between the first detection signal and second detection signal.

Claim 25

An optical disk having at least one track for recording, reading and/or erasing data, the or each track being provided with an adjacent track groove the radial position of at least one boundary of which varies about the disk axis in a detectable manner so as to provide an indication of a location within the track.

Claim 26

An optical disk as claimed in claim 25 wherein changes in radial position of said at least one boundary represent address information.

Claim 27

An optical disk as claimed in claim 25 wherein a change in radial position of said at least one boundary represents an index mark at a predetermined position around the disk axis.

Claim 28

An optical disk drive which selects a desired track on an optical disk by counting the number of tracks crossed by a light beam spot projected onto the disk as said beam moves radially relative to the disk, the track count being derived by processing a signal representing reflected light intensity in such a manner as to disregard short term signal changes resulting from changes in radial positions of track groove boundaries.