Pulse-based writing for magnetic storage media

Patent metadata

Field	Value
Publication number	US-11557316-B2
Application number	US-202217653446-A
Country	US
Kind code	B2
Filing date	Mar 3, 2022
Priority date	Aug 21, 2018
Publication date	Jan 17, 2023
Grant date	Jan 17, 2023

Abstract

The present disclosure describes aspects of pulse-based writing for magnetic storage media. In some aspects, a pulse-based writer of magnetic storage media determines that a string of data bits having a same polarity corresponds to a magnet longer than a threshold associated with a magnetic media writer. The pulse-based writer inserts, into the string of data bits, a transition to a polarity opposite to the same polarity of the string of data bits. The string of data bits including the inserted transition is then transmitted to the magnetic media writer to cause a write head of the writer to pulse while writing the magnet to magnetic storage media. Various aspects may also implement a control signal to mask a transition or control polarity of the magnetic media writer. By so doing, magnets may be written to the magnetic storage media more efficiently or with less distortion to neighboring tracks.

First claim

What is claimed is:

1. A method comprising:
determining that a string of data bits having a same polarity corresponds to a magnet formed on a magnetic storage media has a magnet length that exceeds a magnet length threshold associated with a magnetic media writer;
asserting, in response to the determining, a signal to the magnetic media writer to prevent a transition in the string of data bits from causing the magnetic media writer to increase write current applied to a write head of the magnetic media writer;
inserting, into the string of data bits, at least one transition to a polarity opposite to the same polarity of the string of data bits; and
transmitting, to the magnetic media writer, the string of data bits including the at least one transition to cause the magnetic media writer to reduce an application of write current applied to the write head while writing the magnet corresponding to the string of data bits to the magnetic storage media.

2. The method of claim 1 , wherein transmitting the string of data bits that includes the at least one transition causes the magnetic media writer to terminate the application of the write current to the write head after writing at least a portion of the magnet and prior to applying other write current to the write head to write another magnet.

3. The method of claim 2 , wherein terminating the application of the write current comprises transitioning a pre-amplifier of the magnetic media writer to an off-state or a pre-bias voltage state prior to applying the other write current to the write head to write the other magnet.

4. The method of claim 1 , wherein the inserting comprises inserting the at least one transition into the string of data bits at a predetermined bit location referenced from at least one of:
a last data bit in the string of data bits having the same polarity;
an end of the magnet to which the string of data bits corresponds; or
a length of the magnet to which the string of data bits corresponds.

5. The method of claim 1 , wherein the at least one transition comprises:
a first transition to the polarity opposite to the same polarity of the string of data bits; and
a second transition subsequent to the first transition to the same polarity of the string of data bits.

6. The method of claim 1 , wherein the at least one transition comprises a first set of one or more transitions, and the method further comprises:
deasserting, subsequent to the transmission of the first set of one or more transitions in the string of data bits, the signal to the magnetic media writer;
inserting, into the string of data bits, a second set of one or more transitions that includes a transition to the same polarity of the string of data bits; and
transmitting, to the magnetic media writer, the string of data bits including the first set of one or more transitions and the second set of one or more transitions, the second set of one or more transitions causing the magnetic media writer to pulse the write current applied to the write head while writing the magnet corresponding to the string of data bits to the magnetic storage media.

7. The method of claim 1 , wherein the string of data bits having a same polarity includes at least three bits of non-return-to-zero (NRZ) or at least three bits of non-return-to-zero inverted (NRZi) encoded data bits.

8. The method of claim 1 , wherein the magnet length threshold is a predefined threshold associated with or based on a geometry of the write head; and
the determining that the string of data bits corresponds to the magnet having the length that is longer than the magnet length threshold includes comparing a consecutive number of the data bits having the same polarity to the magnet length threshold.

9. An apparatus comprising:
an interface to receive data from a host;
a disk of magnetic storage media to store the data;
a magnetic media writer configured to write, via a write head of the magnetic media writer, the data to the magnetic storage media as respective magnets that correspond to data bits of the data; and
a write current controller configured to:
determine that a string of the data bits having a same polarity corresponds to a magnet having a length that is longer than a magnet length threshold associated with the magnetic media writer;
assert, in response to the determination, a signal to the magnetic media writer to prevent the magnetic media writer from increasing write current applied to the write head in response to a transition in the string of data bits;
insert, into the string of data bits, at least one transition to a polarity opposite to the same polarity of the string of data bits; and
transmit, to the magnetic media writer, the string of data bits including the at least one transition to cause the magnetic media writer to reduce an application of write current applied to the write head while writing the magnet corresponding to the string of data bits to the magnetic storage media.

10. The apparatus of claim 9 , wherein the transmission of the string of data bits that includes the at least one transition causes the magnetic media writer to terminate the application of the write current to the write head after writing at least a portion of the magnet and prior to application of write current to the write head to write another magnet to the magnetic storage media.

11. The apparatus of claim 9 , wherein the write current controller is further configured to:
insert the at least one transition into the string of data bits at a predetermined bit location referenced from at least one of:
a last data bit in the string of data bits having the same polarity;
an end of the magnet to which the string of data bits corresponds; or
a length of the magnet to which the string of data bits corresponds.

12. The apparatus of claim 11 , wherein the predetermined bit location in the string of data bits comprises:
at least four data bits from the last data bit in the string of data bits having the same polarity;
at least four magnet periods from the end of the magnet to which the string of data bits corresponds; or
at least for magnet periods from a terminating point of the length of the magnet to which the string of data bits corresponds.

13. The apparatus of claim 9 , wherein the at least one transition comprises a first set of one or more transitions, and the write current controller is further configured to:
deassert, subsequent to the transmission of the first set of one or more transitions in the string of data bits, the signal to the magnetic media writer;
insert, into the string of data bits, a second set of one or more transitions that includes a transition to the same polarity of the string of data bits; and
transmit, to the magnetic media writer, the string of data bits including the first set of one or more transitions and the second set of one or more transitions, the second set of one or more transitions causing the magnetic media writer to pulse the write current applied to the write head while writing the magnet corresponding to the string of data bits to the magnetic storage media.

14. The apparatus of claim 13 , wherein:
the application of the write current to the write head includes a baseline quantity of write current; and
the pulse of write current applied to the write head comprises an overshoot quantity of write current that includes a sum of the baseline quantity of write current and another quantity of write current of a same polarity as the baseline quantity of write current.

15. The apparatus of claim 9 , wherein:
the magnet length threshold is a predefined threshold as

Assignees

• Marvell Asia Pte Ltd

Inventors

• Oberg Mats
• Fang Hao

Classifications

• G11B20/1403 Primary

  characterised by the use of two levels · CPC title

• G11B2005/0026

  Pulse recording · CPC title

• G11B2005/0032

  Transducing means or record carriers including or interacting with each other through interposition of, a physically controllable magnetic flux masking or focusing element · CPC title

• G11B20/10222

  clock-related aspects, e.g. phase or frequency adjustment or bit synchronisation (dedicated sync patterns in the modulation code G11B20/1403) · CPC title

• H03M5/06

  Code representation, e.g. transition, for a given bit cell depending only on the information in that bit cell · CPC title