Apparatus, system, and method for detecting the formation of a short between a magnetoresistive head and a head substrate

• US 8,044,816 B2
• Filed: 02/01/2007
• Issued: 10/25/2011
• Est. Priority Date: 02/01/2007
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Czarnecki, Stanley W., Axtman, Brian, Biskeborn, Robert Glenn, Tretter, Larry LeeRoy
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): Mahase; Pameshanand
• Application Number:
  US11/670,406
• Publication Number:
  US 20080186634A1
• Time in Patent Office: 1,727 Days
• Field of Search: 360/66, 360/25
• US Class Current: 340/650
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106
• CPC Class Codes: G11B 5/41 Cleaning of heads of record carriers G11B23/50

Abstract

An apparatus, system, and method are disclosed for detecting the formation of a short between a magnetoresistive (“MR”) head and a head substrate. The apparatus is presented with a logic unit containing a plurality of modules configured to functionally execute the necessary steps of generating a baseline electric potential level between a head substrate and ground, monitoring the level of the electric potential between the head substrate and ground, and detecting the formation of a short circuit between the MR head and the head substrate by detecting a change in the electric potential level monitored by the monitoring module from the baseline level to a predetermined threshold level. Beneficially, such an apparatus, system, and method would reduce read errors on the magnetic tape storage system, the time and resources required to recover from such errors, and allow for preventative measures to obviate contamination short related failures of tape drive systems.

Claims

1. An apparatus for detecting the formation of a short between a magnetoresistive (“

MR”

) head and a head substrate, the apparatus comprising;

a biasing module configured to generate a baseline electric potential level between a head substrate of the MR head and ground, the MR head comprising the head substrate and one or more of writer head elements, reader head elements, and servo head elements;

a monitoring module configured to monitor the level of the electric potential between the head substrate and ground; and

a detection module configured to detect the formation of a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in the electric potential level monitored by the monitoring module from the baseline level to a predetermined threshold level.

2. The apparatus of claim 1, wherein the biasing module further comprises a substrate biasing module and a head biasing module, wherein the substrate biasing module has a high equivalent resistance with respect to the head biasing module.

3. The apparatus of claim 2, wherein the substrate biasing module comprises a voltage divider circuit configured to generate a predetermined baseline electric potential level using a substrate voltage reference resistor.

4. The apparatus of claim 3, wherein the head substrate to ground resistance characterized by a short between the head substrate and one or more of the writer head elements, reader head elements, and servo head elements in series with a low resistance head biasing module in parallel combination with the substrate voltage reference resistor is lower than the substrate voltage reference resistor'"'"'s actual resistance to ground.

5. The apparatus of claim 1, wherein the detection module is further configured to detect a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in electric potential level between the head substrate and ground resulting from a change in resistance between the head substrate and ground.

6. The apparatus of claim 1, wherein the detection module checks the electric potential level monitored by the monitoring module when a tape cassette is ejected.

7. The apparatus of claim 1, further comprising a cleaning module configured to manage head cleaning in response to the detection module detecting a short circuit.

8. The apparatus of claim 1, further comprising a notification module configured to notify a tape drive user when a short circuit is detected.

9. A system for detecting the formation of a short between a magnetoresistive (“

MR”

) head and a head substrate, the system comprising;

a magnetic tape cassette configured to store data on a magnetic tape;

a magnetic tape drive configured to;

generate a baseline electric potential level between a head substrate of the MR head and ground, the MR head comprising the head substrate and one or more of writer head elements, reader head elements, and servo head elements;

monitor the level of the electric potential between the head substrate and ground; and

detect the formation of a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in the electric potential level monitored by the monitoring module from the baseline level to a predetermined threshold level; and

a head cleaning device configured to clean the MR head and head substrate on the magnetic tape drive.

10. The system of claim 9, wherein the head substrate to ground resistance characterized by a short between the head substrate and the MR head in series with a low resistance head biasing module in parallel combination with the substrate voltage reference resistor is lower than the substrate voltage reference resistor'"'"'s actual resistance to ground.

11. The system of claim 9, wherein the magnetic tape drive is further configured to detect a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in electric potential level between the head substrate and ground resulting from a change in resistance between the head substrate and ground.

12. The system of claim 9, wherein the magnetic tape drive is further configured to manage head cleaning with the head cleaning device in response to detecting a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate.

13. The system of claim 12, wherein the MR heads on the magnetic tape drive are automatically cleaned with the head cleaning device in response to detection of a short circuit between the MR head and the head substrate.

14. The system of claim 9, wherein the magnetic tape drive is further configured to notify a tape drive user to load the head cleaning device when a short circuit is detected.

15. A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform an operation for detecting the formation of a short between a magnetoresistive (“

MR”

) head and a head substrate, the operation comprising;

generating a baseline electric potential level between a head substrate of the MR head and ground, the MR head comprising the head substrate and one or more of writer head elements, reader head elements, and servo head elements;

monitoring the level of the electric potential between the head substrate and ground; and

detecting the formation of a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in the electric potential level monitored by the monitoring module from the baseline level to a predetermined threshold level.

16. The signal bearing medium of claim 15, wherein generating further comprises generating an electric potential of about 1.5 Volts between the head substrate and ground.

17. The signal bearing medium of claim 15, wherein detecting further comprises checking the electric potential between the head substrate and ground when a tape cassette is ejected.

18. The signal bearing medium of claim 15, further comprising managing head cleaning in response to detecting a short circuit.

19. The signal bearing medium of claim 15, further configured to notify a tape drive user to load the head cleaning device when a short circuit is detected.

20. A method for detecting the formation of a short between a magnetoresistive (“

MR”

) head and a head substrate, the method comprising;

generating a baseline electric potential level between a head substrate of the MR head and ground, the MR head comprising the head substrate and one or more of writer head elements, reader head elements, and servo head elements;

monitoring the level of the electric potential between the head substrate and ground; and

detecting the formation of a short circuit between one or more of the writer head elements, reader head elements, and servo head elements and the head substrate by detecting a change in the electric potential level monitored by the monitoring module from the baseline level to a predetermined threshold level.