Patent EP0502243A2 successfully refreshed from Google Patents.
EP0502243A2
Expired / Lapsed
EP
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Electronic offset compensation of the continuous composite track error signal in optical recording
Assignee: HP Inc
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Filing: 1991-09-27
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Granted: —
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Expires: 2011-09-27
Abstract
Abstract When doing multitrack seek or a single track jump, the midpoint between the maximum and the minimum of the tracking error signal is determined. A peak detector (31) detects the positive peak and the negative peak. These maximum and minimum values are stored in a sample and hold circuit (32). A summing circuit (33) determines the midpoint between the maximum and the minimum of the tracking error signal. An operational amplifier (35) provides a true error signal to the servo control system (14) that provides the appropriate servo operating point. The invention is based on the fact that even though there is no absolute reference signal indicating the appropriate on-track position, the tracking servo system (14) obtains the track error signal over the whole range of positions relative to track center when doing a multitrack seek or a single track jump. The appropriate servo operating point is the midpoint between the maximum and the minimum of the track error signal. This provides compensation for level shifts due to factors such as beam displacement, or detector mispositioning, changes in read/write beam profile, and disk tilt. The present invention solves the key disadvantage of the continuous groove tracking method by eliminating tracking offsets without adding additional information to the disk. It also avoids imposing overhead on the data channel. It compensates for effects of disk tilt, detector misalignment, detector and amplifier offsets, and beam decentration due to fine tracking.
Inventors
- 👤 Bernard W. Bell, Jr.
- 👤 David K. Campbell
- 👤 Henryk Birecki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:54
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08517; G11B7/09; G11B7/094
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
284 words
In an optical disk recording system comprising an optical disk (28) having a plurality of lands separated by grooves, a reading and writing mechanism (25) adapted to read and write data from and to the disk (28) by means of an optical beam, and a controller (12) coupled to the reading and writing mechanism (25) and the disk (28) for controlling the reading and writing of data from and to the disk (28), and having a servo mechanism (14) optically coupled to the disk (28) and electronically coupled to the controller (12) for providing feedback data indicative of the position of the optical beam relative to the lands of the disk, wherein the improvement is characterized by: a peak detector (31) coupled to the servo mechanism (14) adapted to detect the voltage levels of respective positive and negative peaks in the signal output of the servo mechanism (14); a sample and hold circuit (32) coupled to the peak detector (31) for sampling and holding the voltage levels of respective positive and negative peaks; summing means (33) coupled to the sample and hold circuit (32) for finding the midpoint between the voltage levels of respective positive and negative peaks; memory means (34) coupled to the sample and hold circuit (32) and to the summing means (33) for storing the summed voltage level in response to a control signal provided by the sample and hold circuit (32); and electronic means (35) coupled to the sample and hold circuit (32) and the memory means (34) for combining the respective output signals provided thereby to produce an error signal that is coupled to the servo mechanism (14) to control the position of the reading and writing mechanism (25).
Claim 2
Dependent Claim
284 words
In an optical disk recording system comprising an optical disk (28) having a plurality of lands separated by grooves, a reading and writing mechanism (25) adapted to read and write data from and to the disk (28) by means of an optical beam, and a controller (12) coupled to the reading and writing mechanism (25) and the disk (28) for controlling the reading and writing of data from and to the disk (28), and having a servo mechanism (14) optically coupled to the disk (28) and electronically coupled to the controller (12) for providing feedback data indicative of the position of the optical beam relative to the lands of the disk, wherein the improvement is characterized by: a peak detector (31) coupled to the servo mechanism (14) adapted to detect the voltage levels of respective positive and negative peaks in the signal output of the servo mechanism (14); a sample and hold circuit (32) coupled to the peak detector (31) for sampling and holding the voltage levels of respective positive and negative peaks; summing means (33) coupled to the sample and hold circuit (32) for finding the midpoint between the voltage levels of respective positive and negative peaks; memory means (34) coupled to the sample and hold circuit (32) and to the summing means (33) for storing the summed voltage level in response to a control signal provided by the sample and hold circuit (32); and electronic means (35) coupled to the sample and hold circuit (32) and the memory means (34) for combining the respective output signals provided thereby to produce an error signal that is coupled to the servo mechanism (14) to control the position of the reading and writing mechanism (25).
Claim 3
Dependent Claim
88 words
The system of Claim 1 wherein the controller (12) is characterized by a sector address detector (36) coupled to the reading and writing mechanism (25) that is adapted to process output signals derived therefrom, including tracking error offset signals and sector information derived from the optical disk (28), that correlates the tracking error offset signals with the sector information, stores the correlated results, and generates an offset output signal that is applied to the servo mechanism (14) to control the position of the reading and writing mechanism (25).
Claim 4
Independent Claim
98 words
A method of controlling the position of the reading and writing mechanism (25) in an optical disk recording system (10), said method characterized by the steps of: detecting the voltage levels of positive and negative peaks in the signal output of a servo detector; summing the voltage levels of the positive and negative peaks to produce a voltage indicative of the midpoint of a summed voltage level; and combining the summed voltage level with the servo detector voltage to produce an output error signal that is adapted to control the position of the reading and writing mechanism (25).
Claim 5
Independent Claim
98 words
A method of controlling the position of the reading and writing mechanism (25) in an optical disk recording system (10), said method characterized by the steps of: detecting the voltage levels of positive and negative peaks in the signal output of a servo detector; summing the voltage levels of the positive and negative peaks to produce a voltage indicative of the midpoint of a summed voltage level; and combining the summed voltage level with the servo detector voltage to produce an output error signal that is adapted to control the position of the reading and writing mechanism (25).
Claim 6
Dependent Claim
67 words
The method of Claim 3 which further characterized by the steps of: correlating the tracking error offset signals with the sector information during track jumps and seek operations to produce a correlated offset signal; and combining the correlated offset signal with the output error signal to produce a combined out put error signal that is adapted to control the position of the reading and writing mechanism (25).
Claim 7
Dependent Claim
96 words
A method of claim 3 which is further characterized by the steps of: sampling and holding the voltage levels of respective positive and negative peaks, and then summing the voltage levels of respective positive and negative peaks to produce a voltage indicative of the midpoint of a summed voltage level; storing the voltage indicative of the midpoint; and combining the summed voltage level with the respective servo detector voltage levels of respective positive and negative peaks to produce an output error signal that is adapted to control the position of the reading and writing mechanism (25).
Claim 8
Dependent Claim
70 words
The method of Claim 5 which further comprises the steps of: correlating the tracking error offset signals with the sector information during track jumps and seek operations to produce a correlated offset signal; storing the correlated offset signal; and combining the correlated offset signal with the output error signal to produce a combined output error signal that is adapted to control the position of the reading and writing mechanism (25).
References Cited (Backward Citations)
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