Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Drum record
Reexamination Certificate
1997-02-24
2002-03-26
Letscher, George J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Drum record
Reexamination Certificate
active
06362933
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to positioning of heads in a disc drive, and more particularly relates to a device for loading and unloading a magnetic head for a disc drive utilizing a piezoelectric element for flexure control.
Rotating disc drives operate by positioning a transducing head on a slider a small distance from a rotating disc surface. The slider is mounted on a flexure to “fly” the head over the disc. Wind from the disc's rotation elevates the slider a small distance from the surface of the disc. The slider is designed with aerodynamic properties that allow the wind to keep it aloft. The flexure connects the head to an actuator arm and has a spring bias to land the head on the disc when the disc is not rotating, yet is sufficiently flexible to permit the slider to elevate over the disc surface due to dynamic wind forces.
Beginning and ending of the “flying” period can be problematic when the rotation (and thus wind) of the disc starts and stops. When the disc is not rotating, there is no wind resistance to keep the head aloft, which will cause the head to fall to the surface of the disc due to the bias of the flexure spring. This situation is typically handled by dedicating a portion of the disc as a “landing zone” for the head to land on. Landing zones are usually textured to reduce stiction and do not contain data. In this configuration, heads “take off” from a landing zone on the disc when the disc begins rotating, due to the wind created by the disc's rotation. The force required for takeoff is not always constant. Stiction between the slider and the landing zone of the disc changes with environmental conditions. Changes in takeoff force can result in inaccurate timing and lost data. The need for a dedicated landing zone reduces the available space for encoding data on the disc, and variable takeoff force from a contacting position on the disc negatively affects the operation of the disc drive system. Therefore, it is apparent that taking off and landing a head on the disc is an imperfect method of loading a head to read and write data.
One method developed to avoid the problems of taking off and landing a ramp or other mechanical engagement device to engage the flexure spring to hold the slider and head above the elevation of the disc surface. The disc begins rotating while the head is out of the disc region, so that the slider does not contact the disc and stiction is therefore not present. This solution involves extra design efforts, manufacturing, and complexity in the starting and stopping operations of the disc drive, and also requires extra space so that the actuator arm can swing into a parked position, off of the data cylinders associated with the disc.
Therefore, there is a need in the disc drive art for an improved head loading and unloading system to control the height of heads and position of flexure springs with respect to the surface of a disc.
SUMMARY OF THE INVENTION
The present invention is a system for positioning a transducing head at a flying elevation proximate a rotating surface of a disc. Control circuitry generates electrical control signals to manage the operation of the positioning system according to operating characteristics of the disc. The system includes an actuator arm and a flexure spring connected to the actuator arm and carrying the head. A piezoelectric device is operatively attached to the flexure spring to control an elevation of the head on the flexure spring from the surface of the disc in response to the electrical control signals from the control circuitry.
One aspect of the invention is an improvement to a disc drive system. The disc drive system includes a rotatable disc having a surface, a transducing head, an actuator arm, a flexure spring connected to the actuator arm and carrying the head, and control circuitry for generating electrical control signals to position the head proximate a predetermined area on the surface of the disc. The improvement is a piezoelectric device operatively attached to the flexure spring to control a height of the head on the flexure spring from the surface of the disc in response to the electrical control signals from the control circuitry.
Another aspect of the invention is a device for loading and unloading a transducing head in a disc drive system. The device includes an actuator arm and a flexure spring connected to the actuator arm and carrying the head. A system operates to move the head on the flexure spring to a first position distant from a disc during an unloading condition, and to move the head on the flexure spring to a second position closer to the disc surface than the first position during a loading condition.
A further aspect of the invention is a loading device for loading a transducing head in a disc drive system. The system includes a rotatable magnetic disc media device having a surface containing a plurality of tracks on which data may be recorded. The head is mounted to a flexure spring which is mounted to an actuator arm for positioning adjacent a selected track to communicate data to and from the selected track. The head has aerodynamic characteristics so that the head flies over the disc surface when the disc is rotated. The loading device includes a piezoelectric device mounted to an actuator arm and an operator mounted to the flexure spring engaging the piezoelectric device. The loading device further includes means for selectively expanding and contracting the piezoelectric device to move the operator engaging the piezoelectric device to selectively load the head.
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Barina Jeffrey G.
Fard Anoush M.
Hawwa Muhammad A.
Krum Richard G.
Mohajerani Khosrow
Dempster Shawn B.
Heller III Edward P.
Letscher George J.
Olson Jonathan E.
Seagate Technology LLC
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