Technique of optimizing read/write channel parameters

Details Technique of optimizing read/write channel parameters Technique of optimizing read/write channel parameters

1999-02-19

2001-08-14

Faber, Alan T. (Department: 2651)

Dynamic magnetic information storage or retrieval

Monitoring or testing the progress of recording

C360S046000, C360S068000

Reexamination Certificate

active

06275346

ABSTRACT:

CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits ruing under 35 U.S.C. § 119 from an application for METHOD OF OPTIMIZING READ/WRITE CHANNEL PARAMETER earlier filed in the Korean Industrial Property Office on Feb. 21, 1998 and there duly assigned Ser. No. 551611998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the optimization of read/write channel parameters in a magnetic disk recording device such as a hard disk drive, and in particular, to techniques for optimizing write channel parameters as well as read channel parameters in accordance with head/zone combination characteristics.
2. Description of the Related Art
A read/write channel encodes write data received from a host computer and outputs the encoded write data to a head, prior to writing the data on a disk. It also decodes data read from the disk and transmits the read data to the host computer. Thus, the read/write channel circuit is a significant factor in determining the data read/write performance. In general, interpretation of an analog signal retrieved from a disk or writing specific data on the disk varies with channel parameter settings for the read/write channel circuit. That is, an error rate during a data read/write operation changes depending on channel parameters.
In this context, a hard disk drive manufacturer determined read/write channel parameters from experiments on several drive samples and applies the determined parameters commonly to all drives. The differences of characteristics of each drive brought about a large difference between the error rates of drives and high error rates, so as to lower the data reproduction capability of a drive. To circumvent this problem, many read channel parameter optimization techniques have been explored. Read channel parameters include the cut-off frequency, filter boost, threshold voltage, and window shift of a read/write channel circuit for use in processing a read signal during reading data. Read channel optimization is a channel parameter estimation procedure in which a specific pattern is written in a channel optimization position of a disk, the pattern is iteratively read, while varying combinations of channel parameters to be optimized, and a total number of errors is calculated during a read operation.
However, the optimization confined to read channel parameters has limits in maximizing drive performance because a specific pattern cannot reliably be written by a head on a channel optimization position of a disk with non-optimized write channel parameters. Hence, write channel parameter optimization should precede read channel parameter optimization.
Further, if head noise and external stresses cause non-repeatable runout, the above read channel parameter optimization method results in a high error rate for a predetermined time period.
In conclusion, the above read channel parameter optimization method cannot optimize read channel combinations due to its distinctive shortcomings of noise generated from the disparity in number between data writes and data reads, the resulting increase of errors, and thus cannot accurately estimate an error rate.
The following patents each discloses features in common with the present invention but do hot teach or suggest the specifically recited technique for optimizing read/write channel parameters of the present invention: U.S. Pat. No. 5,831,782 to Kohno et al., entitled Method And Apparatus For Supplying Optimal Bias Current To A Magnetic Head, U.S. Pat. No. 5,726,821 to Cloke et al., entitled Programmable Preamplifier Unit With Serial Interface For Disk Data Storage Device Using MR Heads, U.S. Pat. No. 4,821,125 to Christensen et al., entitled Compensation Of Write Current And Delta-V For Recording Component And Radial Position, U.S. Pat. No. 5,121,262 to Squires et al., entitled Disk drive System Employing adaptive Read/Write Channel Controls And Method Of Using Same, U.S. Pat. No. 5,408,367 to Emo, entitled Method Of Optimizing Operation Of disk Drive, U.S. Pat. No. 5,258,876 to Danner et al., entitled Zone Bit Recording With Write Compensation, U.S. Pat. No. 5,537,264 to Pinteric, entitled Method For Optimally Selecting Media Transfer Rates For Different Data Heads Based On Individual Data Head Performance, U.S. Pat. No. 5,430,581 to Moribe et al., entitled Method And Apparatus For Optimizing The Recording and Reproducing Of Information From Magnetic Disks, U.S. Pat. No. 5,657,176 to Moribe et al., entitled Method And Apparatus For Optimizing The Recording And Reproducing Of information From Magnetic Disks, U.S. Pat. No. 5,771,131 to Pirzadeh, entitled Tracking In Hard Disk Drive Using Magnetoresistive Heads, U.S. Pat. No. 5,107,378 to Cronch et al., entitled Adaptive Magnetic Recording And Readback System, U.S. Pat. No. 5,262,907 to Duffy et al., entitled Hard Disc Drive With Improved Servo System, U.S. Pat. No. 5,121,260 to Asakawa et al., entitled Read Channel Optimization System, U.S. Pat. No. 5,610,776 to Oh, entitled Method Of optimizing Read Channel Of disk Drive Recording Apparatus By Using Error Rate, U.S. Pat. No. 5,600,500 to Madsen et al., entitled Performance Based Write Current Optimization Process, U.S. Pat. No. 5,687,036 to Kassab, entitled Selection Of Optimum Write Current In A Disc Drive To Minimize The Occurrence Of Repeatable Read Errors, and U.S. Pat. No. 5,774,285 to Kassab et al., entitled Selection Of optimal Read/Write Channel Parameters In A Hard Disc Drive.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a write channel parameter optimization technique in a hard disk drive having a read/write channel circuit, which can decrease a data read/write error rate through optimization of write channel parameters to thereby increase drive performance.
Another object of the present invention is to provide a read channel parameter optimization technique in a hard disk drive having a read/write channel circuit, which removes noise involved in read channel parameter optimization to enable an accurate error rate estimation.
A further object of the present invention is to provide a read/write channel parameter optimization technique in a hard disk drive having a read/write channel circuit, which separately optimizes write and read channel parameters to thereby increase drive performance and reliability.
To achieve the above objects, there is provided a read/write channel parameter optimization technique in a hard disk drive having a read/write channel circuit. In the read/write channel parameter optimization technique, a track is designated as a test track in each of a plurality of head/zone combinations. An optimum level of each write channel parameter is searched for by performing data pattern write/read operations on the designated test track, and recording one of the default and optimum levels of the write channel parameter as an optimized write channel parameter value for a selected head/zone combination. Finally, an optimum combination of read channel parameters is searched for by calculating the error number for each read channel parameter combination from data pattern write and read operations of the same number on the designated test, and recording one of the searched optimum read channel parameter combination and a default read channel parameter combination as an optimized read channel parameter combination for the selected head/zone combination.


REFERENCES:
patent: 4821125 (1989-04-01), Christensen et al.
patent: 5107378 (1992-04-01), Cronch et al.
patent: 5121260 (1992-06-01), Asakawa et al.
patent: 5121262 (1992-06-01), Squires et al.
patent: 5258876 (1993-11-01), Danner et al.
patent: 5262907 (1993-11-01), Duffy et al.
patent: 5408367 (1995-04-01), Emo
patent: 5430581 (1995-07-01), Moribe et al.
patent: 5537264 (1996-07-01), Pinteric
patent: 5600500 (1997-02-01), Madsen et al.
patent: 5610776 (1997-03-01), Oh
patent: 5657176 (1997-08-01), Moribe et al.
patent: 5687036 (1997-11-01), Kassab
patent: 5726821 (1998-03-01), Cloke et al.
patent: 5771131 (1998-06-01),

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