公开(公告)号：HK139294A

公开(公告)日：1994-12-16

申请号：HK139294

申请日：1994-12-08

Applicant: IBM

Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS LEONARDUS

IPC: G11B5/39 ,  G11B5/00 ,  G11B5/02 ,  G11B5/40 ,  G11B19/04 ,  H03F3/72

Abstract: The invention relates to a protection circuit for a magnetoresistive (MR) element (Rh) having a first terminal and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current (J1) through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current (Iref). According to the invention, circuit means (R,R,B) coupled across the MR element (Rh) senses the centre potential of the MR element substantially midway between the first and second terminals, and a feedback circuit (B) responsive to the sensed centre potential adjusts the current output of the first current source (J1) to maintain the centre potential to a selected reference voltage (Vcentre) to protect the MR element (Rh) from short circuits to a conductive area of the magnetisable recording medium being read by the MR element.

公开(公告)号：DE68914075T2

公开(公告)日：1994-10-20

申请号：DE68914075

申请日：1989-09-20

Applicant: IBM

Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS LEONARDUS

IPC: G11B5/39 ,  G11B5/00 ,  G11B5/02 ,  G11B5/40 ,  G11B19/04 ,  H03F3/72

Abstract: The invention relates to a protection circuit for a magnetoresistive (MR) element (Rh) having a first terminal and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current (J1) through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current (Iref). According to the invention, circuit means (R,R,B) coupled across the MR element (Rh) senses the centre potential of the MR element substantially midway between the first and second terminals, and a feedback circuit (B) responsive to the sensed centre potential adjusts the current output of the first current source (J1) to maintain the centre potential to a selected reference voltage (Vcentre) to protect the MR element (Rh) from short circuits to a conductive area of the magnetisable recording medium being read by the MR element.

公开(公告)号：DE68914075D1

公开(公告)日：1994-04-28

申请号：DE68914075

申请日：1989-09-20

Applicant: IBM

Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS LEONARDUS

IPC: G11B5/39 ,  G11B5/00 ,  G11B5/02 ,  G11B5/40 ,  G11B19/04 ,  H03F3/72

Abstract: The invention relates to a protection circuit for a magnetoresistive (MR) element (Rh) having a first terminal and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current (J1) through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current (Iref). According to the invention, circuit means (R,R,B) coupled across the MR element (Rh) senses the centre potential of the MR element substantially midway between the first and second terminals, and a feedback circuit (B) responsive to the sensed centre potential adjusts the current output of the first current source (J1) to maintain the centre potential to a selected reference voltage (Vcentre) to protect the MR element (Rh) from short circuits to a conductive area of the magnetisable recording medium being read by the MR element.