Optical disk sector servo patterns

Claim 2

An optical disk for storing data comprising: a substrate and an optical recording layer on said substrate, said recording layer defining a plane and having a plurality of concentric recording tracks subdivided into a plurality of servo sectors and data sectors; said servo sectors having a servo pattern characterized by an arrangement of features having predetermined sizes and shapes in several radial rows so that a track error signal can be found by comparing multi-phase signals proportional to distances between edges of features in one row and proportional to distances between edges of features in some other row, the servo pattern being composed of a plurality of rows of said features in the form of depressions in or raised areas on the plane of said recording layer; and said features having lengths within a radial direction of a row and being separated by spaces along said radial direction greater than a width of said recording tracks.

Claim 3

The optical disk recited in claim 1 wherein the number of phases of said servo pattern is three or more phases.

Claim 4

The optical disk recited in claim 1 wherein the number of rows of said areas composing said servo pattern is three or more.

Claim 5

The optical disk recited in claim 1 wherein the number of phases of said servo pattern is three composed of three rows of said areas.

Claim 6

The optical disk recited in claim 1 wherein the number of phases of said servo pattern is four composed of three rows of said areas.

Claim 7

The optical disk recited in claim 1 wherein the number of phases of said servo pattern is four composed of four rows of said areas.

Claim 8

The optical disk recited in claim 6 wherein edge separations between said areas are just greater than a reading laser spot size and reflectance values from all four rows are summed to form a track error signal whose slope, and resultant servo gain, is unaffected by variations in spot size, area lengths and track offset position.

Claim 9

The optical disk recited in claim 6 wherein the four phase pattern generates redundant track error signals whereby defects in a servo sector area can be compensated or bypassed to avoid tracking errors.

Claim 10

The optical disk recited in claim 1 wherein said servo pattern has a pattern period, within a row, of three or more times the track width.

Claim 11

The optical disk recited in claim 1 wherein edge separations between said areas are just greater than a reading laser spot size whereby a variation of track error signal slope with spot size or area length is minimized.

Claim 12

The optical disk recited in claim 1 further comprising within said servo sectors a digital gray code formed of rows of areas in a plane different than the plane of said layer and extending, without interruption, from an inner diameter to an outer diameter of said disk.

Claim 13

The optical disk recited in claim 11 wherein said gray code defines groups of tracks and said servo pattern is decoded to identify a specific track within a group thereby minimizing the number of rows of said areas used for said gray code.

Claim 14

The optical disk recited in claim 11 wherein said code comprises at least one straight edge and two or more edges that are located at designated positions according to the gray code such that the minimum stripe width and spacing are an integer multiple of the spacing between adjacent designated edge positions of the code.

Claim 15

The optical disk recited in claim 11 wherein said code has a length of sixteen with two variable edges that can occupy eight positions.

Claim 16

The optical disk recited in claim 11 wherein said code has a length of sixteen with three variable edges that can occupy eight positions.

Claim 17

The optical disk recited in claim 1 wherein said areas are depressions in said layer.

Claim 18

The optical disk recited in claim 1 wherein said areas are mounds on said layer.

Claim 19

The optical disk recited in claim 1 wherein said servo pattern is formed using a photolithographic process.

Claim 20

An optical data storage system comprising: an optical disk for storing data; an optical head assembly radially movable adjacent a recording surface of aid optical disk for detecting concentric recording tracks on said optical disk; address register means for temporarily storing an address of one of said recording tracks; first servo means responsive to said address for radially moving said optical head assembly to seek an addressed recording track; second servo means responsive to said address for radially moving said optical head assembly to follow the addressed recording track after said first servo means positions said optical head assembly over the addressed recording track; said optical disk comprising a substrate and an optical recording layer on said substrate, said recording layer defining a plane and having a plurality of concentric recording tracks subdivided into a plurality of servo sectors and data sectors; said servo sectors having a servo pattern characterized by an arrangement of features having predetermined sizes and shapes in several radial rows so that a track error signal can be generated by said second servo means by comparing multi-phase signals proportional to distances between edges of features in one row and proportional to distances between edges of features in some other row, the servo pattern being composed of a plurality of rows of said features in the form of depressions in or raised areas on the plane of said recording layer; and said features having lengths within a radial direction of a row and being separated by spaces along said radial direction greater than a width of said recording tracks.

Claim 21

An optical data storage system comprising: an optical disk for storing data; an optical head assembly radially movable adjacent a recording surface of aid optical disk for detecting concentric recording tracks on said optical disk; address register means for temporarily storing an address of one of said recording tracks; first servo means responsive to said address for radially moving said optical head assembly to seek an addressed recording track; second servo means responsive to said address for radially moving said optical head assembly to follow the addressed recording track after said first servo means positions said optical head assembly over the addressed recording track; said optical disk comprising a substrate and an optical recording layer on said substrate, said recording layer defining a plane and having a plurality of concentric recording tracks subdivided into a plurality of servo sectors and data sectors; said servo sectors having a servo pattern characterized by an arrangement of features having predetermined sizes and shapes in several radial rows so that a track error signal can be generated by said second servo means by comparing multi-phase signals proportional to distances between edges of features in one row and proportional to distances between edges of features in some other row, the servo pattern being composed of a plurality of rows of said features in the form of depressions in or raised areas on the plane of said recording layer; and said features having lengths within a radial direction of a row and being separated by spaces along said radial direction greater than a width of said recording tracks.

Claim 22

The optical data storage system as recited in claim 19 wherein the number of phases of said servo pattern on said optical disk is three or more phases.

Claim 23

The optical data storage system as recited in claim 19 wherein the number of rows of said areas composing said servo pattern on said optical disk is three or more.

Claim 24

The optical data storage system as recited in claim 19, wherein the number of phases of said servo pattern on said optical disk is three composed of three rows of said areas.

Claim 25

The optical data storage system as recited in claim 19 wherein the number of phases of said servo pattern on said optical disk is four composed of three rows of said areas.

Claim 26

The optical data storage system as recited in claim 19 wherein the number of phases of said servo pattern on said optical disk is four composed of four rows of said areas.

Claim 27

The optical data storage system as recited in claim 19 wherein said servo pattern on said optical disk has a pattern period, within a row, of three or more times the track width.

Claim 28

The optical data storage system as recited in claim 19 wherein edge separations between said areas on said optical disk are just greater than a reading laser spot size whereby a variation of track error signal slope with spot size or area length is minimized.

Claim 29

The optical data storage system as recited in claim 19 further comprising within said servo sectors on said optical disk a digital gray code formed of rows of areas in a plane different from the plane of said layer and extending, without interruption, from an inner diameter to an outer diameter of said disk.

Claim 30

The optical data storage system as recited in claim 19 wherein said areas are depressions in said layer.

Claim 31

The optical data storage system as recited in claim 19 wherein aid areas are mounds on said layer.

Claim 32

The optical disk storage system as recited in claim 19 wherein said servo pattern on said optical disk is formed using a photolithographic process.