Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Drum record
Patent
1997-05-01
2000-02-15
Heinz, A. J.
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Drum record
G11B 556
Patent
active
060259752
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a dual-stage actuation system for a disc drive, and more particularly to a microactuator for effecting fine positioning of an entire E-block.
Radial track density in disc drives continues to increase, resulting in an increased need for extremely precise head positioning systems. Voice coil motor (VCM) actuators are well-suited to effect coarse positioning, but lack the resolution to finely position and center a transducing head over a selected track. This inadequacy has led to a variety of proposals for a second stage microactuator to effect fine positioning in high track density disc drives.
The microactuator proposals have taken several forms, from an electrostatic microactuator attached to the slider carrying the transducing head, to a piezoelectric microactuator installed at the head suspension mounting block at a distal end of the actuator arm. These proposals all associate the microactuator with components of each individual actuator arm, which imposes an artificial minimum thickness constraint on the actuator arms. In other words, the actuator arms must be thick enough to accommodate the microactuator. This constraint contradicts the general design objective of minimizing the mass of the actuator arms in the disc drive system. In addition, the proposed designs locate the microactuator a substantial distance from the E-block pivot, introducing head skew and failing to maximize the displacement of the head for a corresponding movement of the microactuator.
Therefore, there is a need in the art for a dual-stage actuation system including a microactuator that does not limit the minimum thickness of the actuator arms, minimizes head skew in fine positioning operations, and maximizes head displacement for a corresponding microactuator movement.
SUMMARY OF THE INVENTION
The present invention is a system for positioning a transducing head of a disc drive over a selected track of a rotatable disc having a plurality of concentric tracks. An actuator assembly includes an E-block body having a cavity. The E-block body is movable about an axis. At least one actuator arm extends from the E-block body. A head suspension mechanism including the transducing head is connected to an end of the actuator arm. A pivot cartridge is provided in the cavity in the E-block body. The E-block body is attached to the pivot cartridge and forms a hinge point between the E-block body and the pivot cartridge. A low resolution motor rotates the actuator assembly about the axis to effect coarse positioning of the head with respect to the selected track of the rotatable disc. A piezoelectric element is provided in the E-block body, and is selectively expanded and contracted based on a voltage across the piezoelectric element to distort the E-block body around the hinge point to effect fine positioning of the head with respect to the selected track of the rotatable disc. In one embodiment, a relief is formed in the E-block body adjacent to the hinge point to facilitate distortion of the E-block body in response to expansion and contraction of the piezoelectric element.
Another aspect of the invention is a method of positioning a transducing head of a disc drive over a selected track of a rotatable disc having a plurality of concentric tracks. An actuator assembly is provided, having an E-block body including a cavity, at least one actuator arm extending from the E-block body, a head suspension mechanism including the transducing head connected to an end of the actuator arm, and a pivot cartridge in the cavity in the E-block body. The E-block body is attached to the pivot cartridge and forms a hinge point between the E-block body and the pivot cartridge. A low resolution motor is operated to rotate the actuator assembly about the axis to effect coarse positioning of the head with respect to the selected track of the rotatable disc. A voltage is applied to selectively expand and contract a piezoelectric element in the E-block body, thereby distorting the E-block body around
REFERENCES:
patent: 4764829 (1988-08-01), Makino
patent: 5189578 (1993-02-01), Mori
patent: 5303105 (1994-04-01), Jorgenson
patent: 5521778 (1996-05-01), Boutaghou
Barina Jeffrey G.
Fard Anoush M.
Hawwa Muhammad A.
Mohajerani Khosrow
Sampietro Joseph M.
Heinz A. J.
Seagate Technology Inc.
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