# US 8,570,848 B2 · Optical accessing system and method for controlling decoding strategy

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- Number: US 8,570,848 B2
- Document ID: US8570848B2
- Status: Granted
- Kind: B2
- Application number: 12/707,303
- Filed: 2010-02-17
- Published: 2010-08-19
- Granted: 2013-10-29
- Earliest claimed: 2009-02-18
- Assignees: Sunplus Technology Co., Ltd.
- Applicants: Lu Chia Tseng; Sih-Kai Wang; Zhi-Hsin Lin
- Inventors: Lu Chia Tseng; Sih-Kai Wang; Zhi-Hsin Lin
- Web page: https://patentgrep.com/patent/US8570848B2

## CPC

- G11B 7/00375: {arrangements for detection of physical defects, e.g. of recording layer}
- G11B 7/0948: {specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts (G11B7/095 takes precedence)}
- G11B 20/10009: {Improvement or modification of read or write signals}
- G11B 20/10481: {optimisation methods}
- G11B 20/18: Error detection or correction; Testing {, e.g. of drop-outs}
- G11B 2020/1853: {using a product code which has inner and outer parity symbols}
- G11B 2220/2537: Optical discs
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

An optical storage system includes an optical pick-up head for receiving and transforming an optical signal into an electric signal; a pre-amplifier for receiving the electric signal and outputting a RF signal and a position error signal; a data and timing recovery unit for receiving the RF signal and generating a modulated signal and a clock signal; an error correction unit for generating a data signal according to the modulation signal and the clock signal; a defect signal generator for receiving the RF signal and generating a defect signal according to the RF signal, wherein the defect signal is enabled when the RF signal has a defect; and an error correction controller for receiving the defect signal and generating an error correction control signal according to the defect signal, wherein the error correction unit further receives the error correction control signal and adjusts the decoding strategy of the error correction unit according to the error correction control signal.

## Claims

### Claim 1

An optical storage system for reading data, comprising:
an optical pick-up head, for receiving and transforming an optical signal into an electric signal;
a pre-amplifier, for receiving the electric signal and then outputting a radio frequency (RF) signal and a position error signal;
a data and timing recovery unit, for receiving the RF signal to generate a modulated signal and a clock signal;
an error correction unit, for receiving the modulated signal and the clock signal to generate a data signal;
a defect signal generator, for generating a defect signal according to the RF signal, wherein the defect signal is enabled when the RF signal has a defect;
a servo controller, for receiving the position error signal and the defect signal and generating a servo control signal; and
an error correction controller, coupled to the defect signal generator, for generating an error correction control signal according to characteristics of the defect signal,
wherein the error correction unit is further coupled to the error correction controller so that a decoding strategy of the error correction unit is adjusted according to the error correction control signal.

### Claim 2 (depends on 1)

The optical storage system as claimed in claim 1, wherein the servo controller further receives the error correction control signal from the error correction controller to adjust a servo controller bandwidth.

### Claim 3 (depends on 1)

The optical storage system as claimed in claim 1, wherein the characteristics of the defect signal comprise a width, a number and a density of the defect signal.

### Claim 4 (depends on 3)

The optical storage system as claimed in claim 3, wherein the error correction controller determines whether the width of the defect signal exceeds a width threshold value, a defect density or a defect number during a detecting cycle, wherein when the width of the defect signal detected during the detecting cycle exceed the predetermined value, the defect is a long defect.

### Claim 5 (depends on 4)

The optical storage system as claimed in claim 4, wherein when the error correction controller does not detect the long defect, and the defect density is smaller than or equal to a first density threshold value, or the defect number is smaller than or equal to a first number threshold value, the decoding strategy and corresponding parameters of the servo controller are set as a minimum erasure setting, a general iteration number, and a general servo controller bandwidth.

### Claim 6 (depends on 5)

The optical storage system as claimed in claim 5, wherein when the error correction controller does not detect the long defect, the defect density is larger than the first density threshold value, and simultaneously the defect number is larger than the first number threshold value, the decoding strategy and the corresponding parameters of the servo controller are set as the minimum erasure setting, a maximum iteration number, and a reduced servo controller bandwidth.

### Claim 7 (depends on 4)

The optical storage system as claimed in claim 4, wherein when the error correction controller detects the long defect, and the defect density is smaller than or equal to a second density threshold value, or the defect number is smaller than or equal to a second number threshold value, the decoding strategy and corresponding parameters of the servo controller are set as a maximum erasure setting, a maximum iteration number, and the general servo controller bandwidth.

### Claim 8 (depends on 7)

The optical storage system as claimed in claim 7, wherein when the error correction controller detects the long defect, the defect density is larger than the second density threshold value, and simultaneously the defect number is larger than the second number threshold value, the decoding strategy and the corresponding parameters of the servo controller are set as a medium erasure setting, a medium iteration number, and a reduced servo controller bandwidth.

### Claim 9

A method for controlling a decoding strategy applied in an optical storage system, comprising following steps:
performing an initializing process to set a detecting cycle, a first density threshold value, a second density threshold value, a first number threshold value, and a second number threshold value and set the decoding strategy and corresponding parameters from a servo controller as a minimum erasure setting, a general iteration number, and a general servo controller bandwidth;
detecting characteristics of a defect signal on an optical disk for reading data, wherein the characteristics of the defect signal on the optical disk are detected during the detecting cycle to generate a defect width, a defect density, and a defect number; and
adjusting the decoding strategy according to the defect width, the defect density, and the defect number, wherein when the defect width of the defect signal detected during the detecting cycle does not exceed a predetermined value, and the defect density is smaller than or equal to the first density threshold value, or the defect number is smaller than or equal to the first number threshold value, the decoding strategy and the corresponding parameters of the servo controller are set as the minimum erasure setting, the general iteration number, and the general servo controller bandwidth.

### Claim 10 (depends on 9)

The method for controlling the decoding strategy of the optical storage system as claimed in claim 9, wherein when the defect width of the defect signal detected within the detecting cycle does not exceed the predetermined value, the defect density is larger than the first density threshold value, and the defect number is larger than the first number threshold value simultaneously, the decoding strategy and the corresponding parameters of the servo controller are set as the minimum erasure setting, a maximum iteration number, and a reduced servo controller bandwidth.

### Claim 11 (depends on 9)

The method for controlling the decoding strategy of the optical storage system as claimed in claim 9, wherein when the defect width of the defect signal detected during the detecting cycle exceeds the predetermined value, and the defect density is smaller than or equal to the second density threshold value, or the defect number is smaller than or equal to the second number threshold value, the decoding strategy and the corresponding parameters of the servo controller are set as a maximum erasure setting, a maximum iteration number, and the general servo controller bandwidth.

### Claim 12 (depends on 11)

The method for controlling the decoding strategy of the optical storage system as claimed in claim 11, wherein when the defect width of the defect signal detected within the detecting cycle exceeds the predetermined value, the defect density exceeds the second density threshold value, and the defect number is larger than the second number threshold value simultaneously, the decoding strategy and the corresponding parameters of the servo controller are set as a medium erasure setting, a medium iteration number, and a reduced servo controller bandwidth.