Dynamic magnetic information storage or retrieval – Head mounting – For moving head into/out of transducing position
Reexamination Certificate
1999-12-22
2001-12-04
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head into/out of transducing position
Reexamination Certificate
active
06327119
ABSTRACT:
FIELD OF THE INVENTION
This application relates to magnetic disc drives and more particularly to a latch mechanism for restraining the actuator arm when subjected to shock loads in a de-energized state.
BACKGROUND OF THE INVENTION
Disc drives are data storage devices that store digital data in magnetic form on a rotating storage medium on a disc. Modern disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (“heads”) mounted to a radial actuator for movement of the heads relative to the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The read/write transducer, e.g. a magnetoresistive read/write head, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the head senses the data previously written on the disc track and transfers the information to the external environment. Critical to both of these operations is the accurate locating of the head over the center of the desired track.
The heads are mounted via flexures at the ends of a plurality of actuator arms that project radially outward from the actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the heads move in a plane parallel with the surfaces of the discs.
Typically, such radial actuators employ a voice coil motor to position the heads with respect to the disc surfaces. The actuator voice coil motor includes a coil mounted on the side of the actuator body opposite the head arms so as to be immersed in the magnetic field of a magnetic circuit comprising one or more permanent magnets and magnetically permeable pole pieces. When controlled direct current (DC) is passed through the coil, an electromagnetic field is set up which interacts with the magnetic field of the magnetic circuit to cause the coil to move in accordance with the well-known Lorentz relationship. As the coil moves, the actuator body pivots about the pivot shaft and the heads move across the disc surfaces. The actuator thus allows the head to move back and forth in an arcuate fashion between an inner radius and an outer radius of the discs.
The actuator arm is driven by a control signal fed to the voice coil motor (VCM) at the rear end of the actuator arm. A servo system is used to sense the position of the actuator and control the movement of the head above the disc using servo signals read from a disc surface in the disc drive. The servo system relies on servo information stored on the disc. The signals from this information generally indicate the present position of the head with respect to the disc, i.e., the current track position. The servo system uses the sensed information to maintain head position or determine how to optimally move the head to a new position centered above a desired track. The servo system then delivers a control signal to the VCM to rotate the actuator to position the head over a desired new track or maintain the position over the desired current track.
In laptop computers, the disc drive must be extremely robust and capable of withstanding shocks and inertial loads due to constant, and often rough, user handling. For this reason, the actuator is typically “parked” with the heads located outboard of the discs and resting on a ramp which protects the heads and discs from adverse loadings. Also, the use of super smooth disc media does not permit the heads to be parked on the discs when the discs ar not rotating. The actuator is typically held in this position with the heads parked by a magnetic latch engaging the VCM molding. However, in mobile applications, such as laptops, due to power and design constraints, the magnetic latch may not be sufficient to positively retain the actuator in the desired position if the drive or entire computer is severely jostled or dropped. Thus it is desirable to provide a latch mechanism which can prevent unwanted actuator arm rotation in these events but which can fit within the cramped confines of a small disc drive housing.
SUMMARY OF THE INVENTION
Against this backdrop the present invention has been developed. The present invention is an inertial latching apparatus for disc drives and in particular small mobile computer drives, that automatically engages the actuator arm to prevent rotation from a parked or latched position due to external shock loads when the drive is de-energized and the actuator arm is in a parked position. In particular, the inertial latch of the invention is designed to engage the actuator arm primarily when the disc drive is subjected to a rotary shock load about an axis parallel to the actuator axis and could also be designed to be sensitive to linear shock loads. The latch engages regardless of the rotational direction of force applied to the drive, but only engages when the drive is subjected to an external inertial or shock load on the drive housing.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description of two exemplary embodiments and a review of the associated drawings.
REFERENCES:
patent: 5189576 (1993-02-01), Morehouse et al.
patent: 5369538 (1994-11-01), Moe et al.
patent: 5404257 (1995-04-01), Alt
patent: 5528437 (1996-06-01), Mastache
patent: 5612842 (1997-03-01), Hickox et al.
patent: 5623384 (1997-04-01), Hickox et al.
patent: 5694271 (1997-12-01), Stefansky
patent: 5742455 (1998-04-01), Boutaghou
patent: 5805384 (1998-09-01), Bronshvatch et al.
patent: 5870256 (1999-02-01), Khanna et al.
patent: 5875075 (1999-02-01), Hickox
patent: 5877922 (1999-03-01), Boutaghou
patent: 6028746 (2000-02-01), Matsumura
patent: 6163440 (2000-12-01), Takahashi et al.
patent: 6185074 (2001-02-01), Wang et al.
patent: 0 107 853 A2 (1983-10-01), None
patent: WO 99/10880 (1999-03-01), None
Barina Jeffrey Gerard
Haas Robert Terry
Kazmierczak Frederick Frank
Maiers Michael Alan
Merchant & Gould
Seagate Technology LLC
Tupper Robert S.
Wahl John R.
Watko Julie Anne
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