Multi-sensor reader with different readback sensitivities

Patent metadata

Field	Value
Publication number	US-9396745-B2
Application number	US-201414201358-A
Country	US
Kind code	B2
Filing date	Mar 7, 2014
Priority date	Mar 7, 2014
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

Apparatus for sensing data from a magnetic recording medium using a multi-sensor reader with different readback sensitivities. In accordance with some embodiments, a data transducing head has first and second read sensors. The first read sensor is optimized for reading data and the second read sensor is optimized to detect thermal asperity (TA) events.

First claim

What is claimed is:

1. An apparatus comprising a data transducing head having a first read sensor optimized for reading data and a second read sensor optimized to detect thermal asperity (TA) events, the first and second read sensors electrically connected in series between opposing first and second electrically conductive connections and electrically connected in parallel to an intermediate third electrically conductive connection, the apparatus further comprising a read circuit that senses a first readback signal using the first and third connections and a second readback signal using the second and third connections.

2. The apparatus of claim 1 , wherein the first read sensor comprises a non-magnetic barrier layer of a first material contactingly disposed between opposing magnetic layers, and the second read sensor comprises a non-magnetic barrier layer of a different second material contactingly disposed between opposing magnetic layers and formed of a different second material.

3. The apparatus of claim 2 , wherein the first material is magnesium oxide (MgO) and the second material is titanium (Ti) or titanium oxide (TiO).

4. The apparatus of claim 1 , wherein the first, second and third electrically conductive connections are bond pads operably coupled to the read circuit.

5. The apparatus of claim 1 , wherein the first and second read sensors are further connected in series between a top shield and a bottom shield, an intermediate shield is disposed in series between the first and second read sensors, the first connection is connected to the top shield, the second connection is connected to the bottom shield, and the third connection is connected to the intermediate shield.

6. The apparatus of claim 1 , wherein the read circuit passes a read bias current through the first and second sensors between the first connection and the third connection during the sensing of the first readback signal from the first read sensor and the sensing of the second readback signal from the second sensor.

7. The apparatus of claim 1 , further comprising a control circuit connected to the transducing head configured to concurrently transduce readback data from first and second tracks using the first and second read sensors during a two dimensional magnetic recording (TDMR) mode of operation, the control circuit further adapted to transduce a readback signal from a third track using the first read sensor while sensing at least one TA event using the second read sensor during a multi-sensor read (MSR) mode of operation.

8. The apparatus of claim 1 , wherein the first read sensor is configured to have a first, higher signal to noise ratio (SNR) response and the second read sensor is configured to have a second, lower SNR response, where the second SNR response is at least 10 dB lower than the first SNR response.

9. The apparatus of claim 1 , wherein the first read sensor has a relatively low thermal coefficient of resistance (TCR and the second read sensor has a relatively higher thermal coefficient of resistance (TCR).

10. The apparatus of claim 1 , wherein each of the first and second read sensors has a tri-layer construction.

11. The apparatus of claim 1 , wherein a selected one of the first or second read sensors has a GMR construction, and a remaining one of the first or second read sensors has a non-GMR construction.

12. An apparatus comprising first and second read sensors adapted to sense magnetic patterns on an adjacent recording surface, the first read sensor comprising a non-magnetic barrier layer contactingly disposed between opposing magnetic layers and formed of a first material to provide an optimized reader response, the second read sensor comprising a non-magnetic barrier layer contactingly disposed between opposing magnetic layers and formed of a different second material to provide a finite thermal coefficient of resistance (TCR) response, the first and second read sensors separated by an intervening conductive shield therebetween and electrically connected in series between a first bond pad and a second bond pad each in turn connected to a read circuit.

13. The apparatus of claim 12 , wherein the first material is magnesium oxide (MgO) and the second material is titanium (Ti) or titanium oxide (TiO).

14. The apparatus of claim 12 , further comprising a third bond pad connected to the intervening conductive shield, the third bond pad connected to the read circuit.

15. The apparatus of claim 14 , wherein a first electrically conductive bond pad is connected to the top shield, a second electrically conductive bond pad is connected to the bottom shield, and a third electrically conductive bond pad is connected to the intermediate shield, wherein a read bias current is flowed between the first and third bond pads so as to successively pass through the first and second read sensors, wherein a first readback signal is sensed from the first read sensor using the first and third bond pads, and wherein a second readback signal is sensed from the second read sensor using the second and third bond pads.

16. The apparatus of claim 12 , further comprising a control circuit connected to the first and second read sensors and configured to concurrently transduce readback data from first and second tracks using the first and second read sensors during a two dimensional magnetic recording (TDMR) mode of operation, the control circuit further adapted to transduce a readback signal from a third track using the first read sensor while sensing at least one thermal asperity (TA) event using the second read sensor during a multi-sensor read (MSR) mode of operation.

17. The apparatus of claim 12 , wherein the first and second read sensors are arranged within a reader sensor in non-overlapping relation in a cross-track direction.

18. The apparatus of claim 12 , wherein the first and second read sensors are arranged within a reader sensor in overlapping relation in a cross-track direction.

19. A two dimensional magnetic recording (TDMR) system comprising:
a first read sensor having a first signal to noise ratio (SNR) response and a relatively lower sensitivity to thermal asperity (TA) events;
a second read sensor electrically connected to the first read sensor having a second SNR response lower than the first SNR response and a relatively higher sensitivity to TA events; and
a read circuit configured to pass a read bias current through the first and second read sensors from a first bond pad to a second bond pad, to sense a first readback signal from the first read sensor responsive to the read bias current using the first bond pad and a third bond pad electrically connected between the first and second read sensors, and to sense a second readback signal responsive to the read bias current from the second read sensor using the first bond pad and the third bond pad.

20. The TDMR system of claim 19 , wherein the first read sensor comprises a tunnel barrier layer of magnesium oxide (MgO) and the second read sensor comprises a tunnel barrier layer of titanium (Ti) or titanium oxide (TiO).

21. An apparatus comprising a data transducing head having a first read sensor optimized for reading data and a second read sensor optimized to detect thermal asperity (TA) events, the first and second read sensors electrically connected in series between opposing first and second electrically conductive connections and electrically connected in parallel to an intermediate third electrically conductive connection, the first read sensor comprising a non-magnetic ba

Assignees

• Seagate Technology Llc

Inventors

• Macken Declan
• Gadbois Jason
• Singleton Eric W
• Wolf John M

Classifications

• G11B5/3932

  Magnetic biasing films · CPC title

• G11B5/3909

  Arrangements using a magnetic tunnel junction · CPC title

• G11B5/3912

  Arrangements in which the active read-out elements are transducing in association with active magnetic shields, e.g. magnetically coupled shields (G11B5/3916 takes precedence) · CPC title

• G11B5/3958

  the active elements being arranged in a single plane, e.g. "matrix" disposition · CPC title

• G11B5/3951 Primary

  the active elements being arranged on several parallel planes · CPC title