Methods and apparatus determining and/or using overshoot control of write current for optimized head write control in assembled disk drives

• US 20030112541A1
• Filed: 11/14/2002
• Published: 06/19/2003
• Est. Priority Date: 12/13/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Cho, Keung Youn, Lee, Sang, Lee, Hae Jung
• Granted Patent: US 6,975,475 B2
• Time in Patent Office: Days
• US Class Current: 360/55
• CPC Class Codes: B65G 7/12 Load carriers, e.g. hooks, slings, harness, gloves, modified for load carrying
• CPC Class Codes: G11B 20/10009 Improvement or modification of read or write signals
• CPC Class Codes: G11B 20/1816 Testing
• CPC Class Codes: G11B 2005/0013 of transducers, e.g. linearisation, equalisation
• CPC Class Codes: G11B 2020/10898 Overwriting or replacing recorded data
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor

Abstract

The invention includes a testing method which may be applied to at least one writer in a disk drive during the self-test phase to generate write parameters, focused on the Over Shoot Control (OSC) of the write current parameter to improve the reliability of write operations by that writer. The Minimum OSC is used for write operations in normal temperatures. The Optimum OSC is used for a first lower temperature range, preferably between essentially 15° Centigrade and essentially 5° Centigrade. The Maximum OSC is preferred below essentially 5° C. The Minimum OSC should preferably guarantee both an Adjacent Track Write (ATW) criteria, as well as guarantee a Write Induced Instability (WII) criteria. The invention includes the write parameter collection, as well as the disk drive containing the generated write parameter collection. The invention also includes the method of using that write parameter collection to control a writer while writing to tracks belonging to the radial zone collection and program systems implementing the invention'"'"'s methods.

Claims

1. A method generating an OverShoot Control (OSC) collection regarding a writer for a radial zone collection of at least three radially consecutive tracks on a rotating disk surface within a disk drive,

wherein said writer is contained within said disk drive,

wherein said writer is comprised of a read-write head communicating with a rotating disk surface, a preamplifier coupled with said read-write head and a channel interface coupled with said preamplifier, within said disk drive

wherein said OSC collection includes an Optimum OSC, a Minimum OSC and a Maximum OSC,

wherein said method is comprised, regarding said writer communicating with said radial zone collection members, of the steps of:

optimizing said OSC collection members to create a Bit Error Rate (BER);

optimizing said Minimum OSC to meet an Adjacent Track Writing (ATW) criteria based upon said BER; and

optimizing said Minimum OSC to meet a Write Induced Instability (WII) criteria.

2. The method of claim 1,

wherein, regarding said writer communicating with said radial zone collection members, the step optimizing said OSC Collection members to create said BER, is further comprised of the steps of:

generating a reference BER and a reference OSC, both based upon an initial channel value collection and an initial OSC value;

finding said Minimum OSC by testing based upon said reference BER and said reference OSC value to create an OSC table containing at least two entries; and

finding said Maximum OSC by testing based upon said reference BER and said reference OSC to update said OSC table;

wherein each of said OSC table entries contains an OSC value and a BER test value; and

wherein said Optimum OSC is determined from said OSC table to have a minimum BER test value.

3. The method of claim 2,

wherein, regarding said writer communicating with said radial zone collection members, the step finding said Minimum OSC, is further comprised of the steps of:

successively decreasing an OSC value from said reference OSC until a bit error rate test reports a BER for said OSC Value outside a first bit error rate range based upon said reference BER; and

setting said Minimum OSC to said OSC value;

wherein the step successively decreasing said OSC value is further comprised of the steps of saving said BER for at least one of said OSC values to said OSC table.

4. The method of claim 2,

wherein, regarding said writer communicating with said radial zone collection members, the step finding said Maximum OSC, is further comprised of the steps of:

successively increasing an OSC value from said reference OSC until a bit error rate test reports a BER for said OSC value outside a second bit error range based upon said reference BER;

setting said Maximum OSC to said OSC value;

wherein the step successively increasing said OSC value is further comprised of the steps of saving said BER for at least one of said OSC values to said OSC table.

5. The method of claim 1,

wherein said radial zone collection includes a first track, two radially neigboring tracks, and a radial neighborhood strip collection containing said first track and said two radially neighboring tracks;

wherein, regarding said writer communicating with said radial zone collection members, the step optimizing said Minimum OSC to meet said ATW criteria, is further comprised of the steps of;

setting an OSC value to said Minimum OSC;

successively decreasing said OSC value whenever an Adjacent Track Write test using said OSC Value provides a BER for at least one of said radial neighborhood strip collection members outside said ATW criteria based upon said reference BER; and

setting said Minimum OSC to said OSC value.

6. The method of claim 5,

wherein the step successively decreasing said OSC value whenever said Adjacent Track Write test is further comprised of the steps of:

repeatedly writing said radially neighboring tracks using said OSC value;

performing said Adjacent Track Write test using said OSC Value providing said BER for each of said radial neighborhood strip collection members until said BER is outside said ATW criteria based upon said reference BER until said BER is outside said ATW criteria based upon said reference BER for said radial collection member;

decreasing said OSC value whenever said BER is outside said ATW criteria based upon said reference BER; and

repeating the previous steps whenever said BER is outside said ATW criteria based upon said reference BER for at least one of said radial collection members.

7. The method of claim 1,

wherein, regarding said writer communicating with said radial zone collection members, the step optimizing said Minimum OSC to meet said WII criteria, is further comprised of the steps of:

setting an OSC value to said Minimum OSC;

successively decreasing said OSC value whenever measuring an Automatic Gain Control (AGC) range and an AGC average, based upon repeated writing using said OSC value of a track belonging to said radial zone collection, indicates said AGC range exceeding a fraction of said AGC average; and

setting said Minimum OSC to said OSC value.

8. The method of claim 7,

wherein the step successively decreasing said OSC value whenever measuring is further comprised of the steps of:

repeatedly writing said track using said OSC value to obtain said AGC average, an AGC minimum and an AGC maximum; and

setting said AGC range to said AGC maximum minus said AGC minimum.

9. A method of generating an OverShoot Control (OSC) collection regarding said writer for all of said radial zone collections on said rotating disk surface within said disk drive of claim 1, comprising the steps of:

for each member of a test zone collection comprising at least four of said radial zone collections, performing the steps of claim 1 regarding said writer; and

interpolating said OSC Collection regarding said writer for all of said radial zone collections based upon said OSC Collections regarding said writer for each of said test zone collection members.

10. A method of read channel optimization regarding said writer of claim 9, comprising the steps of:

performing the steps of claim 9;

and

wherein said method, for each of said radial zone collections, is further comprised of the step of;

read channel optimizing based upon said Minimum OSC regarding said writer for said radial zone collection to create a write parameter collection including said OSC collection regarding said writer and for said radial zone collection.

11. The method of claim 10, further comprising at least one member of the collection comprising the steps of:

read channel optimizing for other parameters based upon a default write current and a default of said OSC to create an initial RCO other parameter list; and

read channel optimizing to create an initial write current and said initial OSC based upon said initial RCO other parameters;

wherein said initial OSC is based at least partially upon said default write current and said default OSC.

12. Said write parameter collection, regarding said writer for at least one of said radial zone collections, as a product of the process of claim 10.

13. A method of making said disk drive of claim 10, comprising the steps of:

performing the steps of claim 10 to create said write parameter collection, regarding said writer for at least one of said radial zone collections; and

installing said write parameter collection into an embedded controller within said disk drive.

14. The method of claim 13,

wherein the step performing the steps of 10, is further comprised of at least one member of the collection comprising the steps of:

performing the steps of claim 10 to create said write parameter collection, regarding said writer for all of said radial zone collections; and

performing the steps of claim 10 to create said write parameter collection, regarding a second of said writers included in said disk drive for at least one of said radial zone collections on a second rotating disk surface communicating with said read-write head included in said second writer;

for each of at least three of said writers, included in said disk drive, communicating with a corresponding disk surface, performing the steps of claim 10 to create said write parameter collection, regarding said writers for at least one of said radial zone collections on said corresponding rotating disk surface; and

for each of said writers, included in said disk drive, performing the steps of claim 10 to create said write parameter collection, regarding said writers for all of said radial zone collections on said corresponding rotating disk surface.

15. Said disk drive as a product of the process of claim 13.

16. A program system for controlling an embedded controller of said disk drive of claim 1, comprising at least two program steps residing in a memory accessibly coupled with a computer within said embedded controller, wherein said program steps implement the steps of claim 1.

17. An apparatus implementing the method of claim 1, comprising a means for each of the steps of claim 1.

18. A method of controlling a writer within a disk drive,

wherein said writer is comprised of a channel interface coupled with a preamplifier, in turn coupled with a read-write head communicating with a rotating disk surface within said disk drive,

wherein said disk drive contains an OverShoot Control (OSC) Collection regarding said writer for a radial zone collection including at least two tracks on said rotating disk surface,

wherein said OSC collection includes an Optimum OSC, a Minimum OSC and a Maximum OSC,

wherein a radial zone collection is comprised of at least three radially consecutive tracks on said rotating disk surface,

wherein said method is comprised the steps of:

using said Minimum OSC for write operations by said writer within said radial zone collection whenever operating within a normal temperature range; and

using at least one of said Optimum OSC and said Maximum OSC for write operations by said writer within said radial zone collection whenever operating below said normal temperature range.

19. The method of claim 18,

wherein the step using at least one of said Optimum OSC and said Maximum OSC is comprised of at least one member of the collection comprising the steps of:

using said Optimum OSC for write operations by said writer within said radial zone collection whenever operating in a first lower temperature range; and

using said Maximum OSC for write operations by said writer within said radial zone collection whenever operating below said first lower temperature range.

20. The method of claim 19,

wherein said first lower temperature range is between approximately 15°

Centigrade and approximately 5°

Centigrade.

21. A program system for controlling an embedded controller of said disk drive of claim 18, comprising at least two program steps residing in a memory accessibly coupled with a computer within said embedded controller, wherein said program steps implement the steps of claim 18.

22. An apparatus implementing the method of claim 18, comprising a means for each of the steps of claim 18.

23. The method of claim 18,

wherein said rotating disk surface includes at least two of said radial zone collections, each- of said radial zone collections includes at least three radially consecutive tracks on said rotating disk surface;

wherein said method is further comprised, for each of at least two of said radial zone collections, of the steps of;

using said Minimum OSC for write operations by said writer within said radial zone collection whenever operating within a normal temperature range; and

using at least one of said Optimum OSC and said Maximum OSC for write operations by said writer within said radial zone collection whenever operating below said normal temperature range.

24. The method of claim 18,

wherein said disk drive includes at least two of said writers, each of said writers comprised of a channel interface coupled with a preamplifier, in turn coupled with a read-write head communicating with a rotating disk surface within said disk drive;

wherein, for each of at least two of said writers, said disk drive contains an OverShoot Control (OSC) Collection regarding said writer for a radial zone collection including at least three radially consecutive tracks on said rotating disk surface;

wherein said method is further comprised, for each of at least two of said writers, of the steps of;

using said Minimum OSC for write operations by said writer within said radial zone collection whenever operating within a normal temperature range; and

using at least one of said Optimum OSC and said Maximum OSC for write operations by said writer within said radial zone collection whenever operating below said normal temperature range.

25. The method of claim 24,

wherein said method is further comprised, for each of said writers, of the steps of:

using said Minimum OSC for write operations by said writer within said radial zone collection whenever operating within a normal temperature range; and

using at least one of said Optimum OSC and said Maximum OSC for write operations by said writer within said radial zone collection whenever operating below said normal temperature range.