System for correcting transducer tangential skew in a disk drive system having two actuators

• US 5,523,901 A
• Filed: 08/08/1994
• Issued: 06/04/1996
• Est. Priority Date: 01/22/1993
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Conner Peripherals Incorporated (Whitehouse Group Ltd.)
• Inventors: Wilson, Aaron, Anderson, Kurt
• Primary Examiner(s): Psitos, Aristotelis
• Assistant Examiner(s): HABERMEHL, JAMES LEE
• Application Number:
  US08/287,462
• Time in Patent Office: 666 Days
• Field of Search: 360/76, 360/78.05, 360/51, 360/61, 360/63, 360/72.2, 360/73.03, 360/77.05, 360/77.08, 360/64, 360/77.02, 360/75, 360/47, 360/49
• US Class Current: 360/77.08
• CPC Class Codes: G11B 5/5578 Multiple actuators addressing the same disk, e.g. to improve data rate or access rate
• CPC Class Codes: G11B 5/59616 Synchronisation; Clocking G11B5/59622 takes precedence

Abstract

In a disk drive system having two actuators, each said actuator having a plurality of transducers, said system employing a transducer switching procedure for switching between a first presently selected transducer and a second to be selected transducer, an apparatus, associated with the nonpackwriting actuator, for controlling the sensing of an address mark by said second transducer, said apparatus comprising an address mark means for generating an address mark search signal to start an address mark search when an address mark is expected to be read by said first transducers; and an adjusting means connected to said address mark means for altering the time when said address mark means will generate said address mark search signal such that said second transducer will read the next address mark to occur on the track being read by said second transducer after said second transducer is selected.

Claims

1. In a disk drive system having two actuators, a packwriting actuator and a nonpackwriting actuator, each said actuator having a plurality of transducers where each said transducer reads and writes data onto and from a disk in said disk drive system and where data written on a disk by a transducer on said packwriting actuator can be read by a transducer on said nonpackwriting actuator and data written on a disk by a transducer on said nonpackwriting actuator can be read by a transducer on said packwriting actuator and where simultaneously a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system and a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system, said system employing a transducer switching procedure for switching between a selected transducer and a to be selected transducer where said selected and to be selected transducers are on said nonpackwriting actuator, an apparatus comprising:

address mark means for generating an address mark search signal to start an address mark search when an address mark is expected to be read by said selected transducer; and

adjusting means connected to said address mark means for altering the time when said address mark means will generate said address mark search signal in response to said transducer switching procedure selecting said to be selected transducer such that said to be selected transducer will read the next address mark to occur on the track being read by said to be selected transducer after said to be selected transducer is selected.

2. The apparatus of claim 1 wherein said adjusting means further comprises;

storage means for storing a tangential skew correction factor for each said transducer associated with said nonpackwriting actuator, said tangential skew correction factor correcting for the tangential skew between one of said transducers established as a reference transducer on said nonpackwriting actuator and each of said remaining transducers on said nonpackwriting actuator;

calculating means connected to said storage means for generating a transducer switching correction factor from said selected transducer'"'"'s tangential skew correction factor and said to be selected transducer'"'"'s tangential skew correction factor; and

correction means connected to said calculating means and said address mark means to adjust, by said transducer switching correction factor, the time when said address mark means generates the next said address mark search signal.

3. The apparatus of claim 2 wherein said calculating means further comprises;

subtracting means for generating said transducer switching correction factor by subtracting said selected transducer'"'"'s tangential skew correction factor from said to be selected transducer'"'"'s tangential skew correction factor.

4. The apparatus of claim 1 wherein said disk drive system having two actuators has a system clock and said address mark means comprises:

counter means step by said system clock;

time means generating a value of the count of said counter when a next address mark search signal is to be generated;

comparator means connected to said counter means and said time means for generating said address mark search signal when said count generated by said time means equals the count of said counter.

5. The apparatus of claim 4 wherein said adjusting means further comprises;

storage means for storing a tangential skew correction factor for each said transducer associated with said nonpackwriting actuator, said tangential skew correction factor correcting for the tangential skew between one of said transducers established as a reference transducer and each of said remaining transducers;

calculating means connected to said storage means for generating a transducer switching correction factor from said selected transducer'"'"'s tangential skew correction factor and said to be selected transducer'"'"'s tangential skew correction factor; and

correction means connected to said calculating means and said address mark means to adjust, by said transducer correction factor, said count value when said address mark means generates the next said address mark search signal.

6. The apparatus of claim 5 wherein said calculating means further comprises;

subtracting means for generating said transducer switching correction factor by subtracting said selected transducer'"'"'s tangential skew correction factor from said to be selected transducer'"'"'s tangential skew correction factor.

7. The apparatus of claim 5 wherein said calculating means further comprises;

adder means connected to said time means and said compare means for adding said count value of said time means to said transducer switching correction factor and inputting said resulting summation to said compare means in place of said count value generated by said time means.

8. The apparatus of claim 7 wherein said calculating means further comprises;

adder means connected to said subtracting means, said time means and said compare means for adding said count value of said time means to said transducer switching correction factor of said subtracting means and inputting said resulting summation to said comparator means in place of said count value generated by said time means.

9. In a disk drive system having two actuators, a packwriting actuator and a nonpackwriting actuator, each said actuator having a plurality of transducers where each said transducer reads and writes data onto and from a disk in said disk drive system and where data written on a disk by a transducer on said packwriting actuator can be read by a transducer on said nonpackwriting actuator and data written on a disk by a transducer on said nonpackwriting actuator can be read by a transducer on said packwriting actuator and where simultaneously a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system and a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system, said system employing a transducer switching procedure for switching between a selected transducer which is presently selected and a to be selected transducer which is to be selected where said selected and to be selected transducers are on said nonpackwriting actuator, a method comprising the steps of:

generating in response to said transducer switching procedure switching from said selected transducer to said to be selected transducer on said nonpackwriting actuator a time value for when an address mark search should be initiated to enable the next address mark to be read by said selected transducers; and

altering said time value for when an address mark search should be initiated such that said to be selected transducer will read the next address mark to occur on a track being read by said to be selected transducer after said to be selected transducer is selected.

10. The method of claim 9 wherein said altering step further comprises the steps of;

storing a tangential skew correction factor for each said transducer associated with said nonpackwriting actuator, said tangential skew correction factor correcting for the tangential skew between one of said transducers established as a reference transducer on said nonpackwriting actuator and each of said remaining transducers on said nonpackwriting actuator;

calculating a transducer switching correction factor from said selected transducer'"'"'s tangential skew correction factor and said to be selected transducer'"'"'s tangential skew correction factor; and

correcting said time value by said transducer switching correction factor.

11. The method of claim 10 wherein said calculating step includes the step of;

subtracting said selected transducer'"'"'s tangential skew correction factor from said to be selected transducer'"'"'s tangential skew correction factor to generate said transducer switching correction factor.

12. The method of claim 9 wherein said disk drive system having two actuators has a system clock and a counter, said method further comprises the steps of;

stepping a counter by said system clock;

establishing a count of said counter for generating an address mark search signal; and

generating said address mark search signal when said count equals the count of said counter.

13. The method of claim 12 wherein said altering step further comprises the steps of;

storing a tangential skew correction factor for each said transducer associated with said nonpackwriting actuator, said tangential skew correction factor correcting for the tangential skew between one of said transducers established as a reference transducer on said nonpackwriting actuator and each of said remaining transducers on said nonpackwriting actuator;

calculating a transducer switching correction factor from said selected transducer'"'"'s tangential skew correction factor and said to be selected transducer'"'"'s tangential skew correction factor; and

correcting said time value by said transducer switching correction factor.

14. The method of claim 13 wherein said calculating step includes the step of;

subtracting said selected transducer'"'"'s tangential skew correction factor from said to be selected transducer'"'"'s tangential skew correction factor to generate said transducer switching correction factor.

15. The method of claim 14 wherein said calculating step further comprises the step of;

adding said count to said transducer switching correction factor to form a resulting summation;

substituting said resulting summation for said count in said generating step for said address mark signal.

16. The method of claim 13 wherein said calculating step further comprises the step of;

adding said count to said transducer switching correction factor to form a resulting summation;

substituting said resulting summation for said count in said generating step for said address mark signal.

17. The method of claim 9 wherein said disk drive system has an address mark detection means for initiating an address mark search as a function of a designated count in a counter within said address mark means and said step of storing further comprises the step of:

generating tangential skew correction factors for each transducer associated with the nonpackwriting actuator in said disk drive system having two actuators.

18. In a disk drive system having two actuators, a packwriting actuator and a nonpackwriting actuator, each said actuator having a plurality of transducers wherein each said transducer reads and writes data onto and from a disk in said disk drive system and where data written on a disk by a transducer on said packwriting actuator can be read by a transducer on said nonpackwriting actuator and data written on a disk by a transducer on said nonpackwriting actuator can be read by a transducer on said packwriting actuator and where simultaneously a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system and a transducer on said nonpackwriting actuator can read or write data from or to a disk in said disk drive system, said system employing a transducer switching procedure for switching between a selected transducer which is presently selected and a to be selected transducer which is to be selected transducer where said selected and to be selected transducers are on said nonpackwriting actuator and said disk drive system has an address mark detection means for initiating an address mark search as a function of a designated count in a counter within said address mark means, a method comprising the steps of:

generating tangential skew correction factors for each transducer associated with the nonpackwriting actuator in said disk drive system having two actuators, wherein said step of generating said tangential skew correction factors comprising the steps of;

a) selecting one of said transducers on said nonpackwriting actuator as a reference transducer whereby said reference transducer is connected to said address mark detector;

b) setting said counter to a nominal designated count such that an address mark is successfully detected;

c) selecting another one of said transducers on said nonpackwriting actuator as a to be selected transducer for which said tangential skew correction factor will be generated;

d) setting said counter to said nominal designated count and determining if the next address mark after said selection of said to be selected transducer is successfully detected and if successfully detected proceeding to step f and said nominal designated count being designated second designated count;

e) if said next sector mark was not successfully detected, systematically alternately increasing and decreasing the count about said nominal designated count in said counter until said next sector mark is successfully detected after switching between said reference transducer and said to be selected transducer, said count in said counter upon successfully detecting said next sector mark being designated as said second designated count;

f) systematically increasing the count above said second designated count in said counter until said next sector mark is unsuccessfully detected after switching between said reference transducer and said to be selected transducer, said count in said counter upon unsuccessfully detecting said next sector mark being designated as maximum count;

g) systematically decreasing the count below said second designated count in said counter until said next sector mark is unsuccessfully detected after switching between said reference transducer and said to be selected transducer, said count in said counter upon unsuccessfully detecting said next sector mark being designated as minimum count;

h) determining the middle count between said maximum count and said minimum count;

i) generating said tangential skew correction factor for said to be selected transducer for switching between said reference transducer and said to be selected transducer equal to the difference of subtracting said nominal designated count from said middle count;

j) storing said tangential skew correction factor for said to be selected transducer in memory; and

k) repeating steps b, c, d, e, f, g, h, i and j for each other transducer associated with said nonpackwriting actuator;

generating in response to said transducer switching procedure switching from said selected transducer to said to be selected transducer on said nonpackwriting actuator a time value for when an address mark search should be initiated to enable the next address mark to be read by said selected transducer; and

altering said time value for when an address mark search should be initiated as a function of said tangential skew correction factor for said to be selected transducer such that said to be selected transducer will read the next address mark to occur on a track being read by said to be selected transducer after said to be selected transducer is selected.

19. The method of claim 18 including the steps of;

l) dividing the data tracks on said disks within said system into zones; and

m) repeating steps a, b, c, d, e, f, g, h, i, j and k for each of said zones.