Passive non-contact magnetic latch for an actuator of a disk drive

• US 5,742,453 A
• Filed: 04/10/1995
• Issued: 04/21/1998
• Est. Priority Date: 10/14/1992
• Status: Expired due to Term

• Current Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Original Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Inventors: MacPherson, Aaron
• Primary Examiner(s): Levy, Stuart S.
• Assistant Examiner(s): Letscher, George J.
• Application Number:
  US08/420,451
• Time in Patent Office: 1,107 Days
• Field of Search: 360/105, 369/244, 369/257, 335/229-234
• US Class Current: 360/256.2
• CPC Class Codes: G11B 19/04 Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions
• CPC Class Codes: G11B 21/02 Driving or moving of heads
• CPC Class Codes: G11B 21/21 with provision for maintaining desired spacing of head from record carrier, e.g. fluid-dynamic spacing, slider
• CPC Class Codes: G11B 21/22 while the head is out of operative position

Abstract

A passive non-contact magnetic latch for latching read/write heads of a disk drive over a landing area of the disk is disclosed. The magnet latch forms a magnetic circuit for capturing a latch tab within an air gap. Magnetic flux lines traverse the latch tab in a direction substantially perpendicular to a direction of movement of the latch tab.

Claims

1. An apparatus for latching an actuator that positions a read/write head of a disk drive, comprising:

a latch arm rotatably coupled to an actuator pivot for the actuator, the latch arm rotating about the actuator pivot as the read/write head moves radially across a disk;

a latch tab coupled to the latch arm, the latch tab having a direction of movement, the latch tab for moving in the direction of movement in response to the latch arm rotating about the actuator pivot;

a U-shaped member coupled to a housing of the disk drive, the U-shaped member for conducting magnetic flux, the U-shaped member including a base, a first arm coupled to the base, and a second arm coupled to the base, the first and second arms extending outwardly from the base in a direction substantially parallel to the direction of movement of the latch tab;

a first magnet having a north pole and a south pole, the south pole of the first magnet being connected to the first arm such that the north pole of the first magnet faces the second arm;

a second magnet having a north pole and a south pole, the north pole of the second magnet being connected to the second arm such that the south pole of the second magnet faces the north pole of the first magnet forming an air gap therebetween wherein the first and second magnets generate a magnetic field across the air gap, substantially all magnetic flux lines of the magnetic field traversing the air gap substantially straight between the facing poles and substantially perpendicular to the direction of movement of the latch tab to minimize magnetic flux outside of said first and second arms.

2. The apparatus of claim 1, wherein the latch tab enters the air gap when the read/write head is positioned over a landing area of the disk.

3. An apparatus for latching an actuator that positions a read/write head of a disk drive, the actuator including a latch arm rotatably coupled to an actuator pivot, a latch tab coupled to the latch arm, the latch tab having a direction of movement, the latch tab for moving in the direction of movement in response to the latch arm rotating about the actuator pivot, the apparatus for latching comprising:

a latch receiving member having a base and two arms separated by an air gap;

a magnetic circuit associated with the latch receiving member, the magnetic circuit including a magnet disposed on the end of said two arms generating a magnetic field across said air gap so as to minimize stray flux outside of said air gap, magnetic flux lines of the magnetic field within the air gap traversing straight across said gap and traversing said latch tab when said tab is in said gap, in a direction substantially perpendicular to the direction of movement of the latch tab; and

means for coupling the magnetic circuit to a housing of the disk drive.

4. The apparatus of claim 3, wherein the magnetic circuit comprises:

a first magnet having a north pole and a south pole; and

a second magnet having a north pole and a south pole, the second magnet being positioned such that the south pole of the second magnet faces the north pole of the first magnet and the air gap is formed between the south pole of the second magnet and the north pole of the first magnet.

5. The apparatus of claim 3, wherein the magnetic circuit comprises:

a U-shaped member coupled to a housing of the disk drive, the U-shaped member for conducting magnetic flux, the U-shaped member including a base, a first arm coupled to the base, and a second arm coupled to the base, the first and second arms extending outwardly from the base towards the actuator in a direction substantially parallel to the direction of movement of the latch tab;

a first magnet having a north pole and a south pole, the south pole of the first magnet being connected to the first arm such that the north pole of the first magnet faces the second arm;

a second magnet having a north pole and a south pole, the north pole of the second magnet being connected to the second arm such that the south pole of the second magnet faces the north pole of the first magnet, wherein the air gap is formed between the north pole of the first magnet and the south pole of the second magnet and stray magnetic flux outside of said first and second arms is minimized.

6. The apparatus of claim 3, wherein the latch tab enters the air gap when the read/write head is positioned over a landing area of a disk.

7. A method for latching an actuator that positions a read/write head of a disk drive, the method comprising the steps of:

providing a latch tab rotatably coupled to an actuator pivot for movement in unison with an actuator;

providing a latch receiving member having a base and two arms separated by an air gap, and a magnet disposed on the end of each of said two arms;

generating a magnetic field across said air gap so as to minimize stray flux outside said air gap such that substantially all magnetic flux lines of the magnetic field within the air gap traverse said gap in a direction substantially perpendicular to a direction of movement of a latch tab; and

positioning the latch tab in the magnetic field in the air gap.

8. An apparatus for latching an actuator that positions a read/write head of a disk drive, comprising:

a latch arm rotatably coupled to an actuator pivot for the actuator, the latch arm rotating about the actuator pivot as the read/write head moves radially across a disk;

a latch tab coupled to the latch arm in response to the latch arm rotating about the actuator pivot;

a U-shaped member for conducting magnetic flux coupled to a housing of the disk drive, the U-shaped member including a base, a first arm coupled to the base, and a second arm coupled to the base, the first and second arms extending outwardly from the base in a direction substantially parallel to the direction of movement of the latch tab;

a first magnet having a north pole and a south pole, the south pole of the first magnet being connected to the first arm such that the north pole of the first magnet faces the second arm;

a second magnet having a north pole and a south pole, the north pole of the second magnet being connected to the second arm such that the south pole of the second magnet faces the north pole of the first magnet forming an air gap therebetween wherein the first and second magnets generate a magnetic field across the air gap in a direction to minimize stray flux outside said first and second arms such that substantially all magnetic flux lines of the magnetic field traversing the air gap are substantially perpendicular to the direction of the movement of the latch tab and such that substantially all magnetic flux lines outside of the air gap that intersect the latch tab will intersect the latch tab in the direction substantially perpendicular to the direction of movement of the latch tab.

9. The apparatus of claim 8, wherein the latch tab enters the air gap when the read/write head is positioned over a landing area of the disk.

10. An apparatus for latching an actuator that positions a read/write head of a disk drive, the actuator including a latch arm having a latch tab and rotatably coupled to an actuator pivot, the latch tab having a direction of movement in response to the latch arm rotating about the actuator pivot, the apparatus for latching comprising:

a latch receiving member including a base member having a pair of spaced arms with magnets disposed on the end of each arm and defining an air gap therebetween;

a magnetic circuit associated with said latch receiving member for generating a magnetic field across said air gap and minimizing stray flux outside said air gap, substantially all magnetic flux lines of the magnetic field within said air gap traversing straight across the air gap in a direction substantially perpendicular to the direction of movement of the latch tab.

11. The apparatus of claim 10, wherein the magnetic circuit comprises:

a first magnet having a north pole and a south pole; and

a second magnet having a north pole and a south pole, the second magnet being positioned such that the south pole of the second magnet faces the north pole of the first magnet and the air gap is formed between the south pole of the second magnet and the north pole of the first magnet.

12. A method for latching a latch tab on a latch arm of an actuator that positions a read/write head of a disk drive, the method comprising the steps of:

generating a magnetic field across an air gap utilizing a U-shaped member for conducting magnetic flux in a direction to minimize stray flux outside the air gap defined by the opposed legs of the U-shaped member such that substantially all magnetic flux lines of the magnetic field within the air gap traverse across the air gap substantially perpendicular to the direction of movement of the latch tab, and

positioning the latch tab in the magnetic field by rotating the latch arm about an actuator pivot as the read/write head moves radially across a disk such that the latch tab which is coupled to the latch arm enters the air gap.