Disk drive with rotary piezoelectric microactuator
View Patent ↗A disk drive with a dual-stage actuator has a moving-slider rotary piezoelectric microactuator as the secondary actuator. The microactuator has a substrate attached to the disk drive suspension. A rotatable frame that supports the slider is attached to a fixed post on the substrate by relatively stiff torsional springs. A piezoelectric driver having a fixed end attached to the substrate provides bidirectional linear displacement of its movable end. The microactuator includes a displacement amplification mechanism. In one embodiment an arm or connecting rod is located between the driver's movable end and the frame. A linkage between the movable end of the driver and a first end of the connecting rod translates the linear displacement of the driver to amplified orthogonal linear displacement of the rod. The second end of the rod is attached to the rotatable frame at a radial distance to cause rotary movement of the frame, and thereby cross-track displacement of the read/write head on the slider.
1. A magnetic recording disk drive comprising:
a magnetic recording disk having a plurality of data tracks;
a read/write head for reading data from and writing data to the disk;
a head carrier for supporting the read/write head;
a primary actuator for coarse positioning the head to a selected track and comprising a primary actuator arm and a suspension attached to an end of the primary actuator arm;
a piezoelectric microactuator for moving the head in a cross-track direction to fine position the head over the selected track, the microactuator comprising:
a substrate attached to the suspension;
a post fixed to the substrate;
a rotatable frame connected to the post by a plurality of torsional springs, the springs permitting rotary movement of the frame about an axis through the post, wherein the head carrier is attached to the rotatable frame;
a single piezoelectric driver having a portion fixed to the substrate and a movable portion having bidirectional linear displacement in a direction generally parallel to the cross-track direction;
a connecting rod having its length oriented generally orthogonal to the cross-track direction and having a driver end connected to the driver movable portion and a frame end connected to the rotatable frame at a radius from the axis of the post;
a linkage connecting the driver movable portion to the driver end of the rod and causing the driver end of the rod to move in a generally linear direction substantially orthogonal to the generally linear cross-track displacement of the driver movable portion, the linkage amplifying the displacement of driver movable portion, whereby the frame end of the rod exhibits a generally linear displacement greater than the generally linear displacement of the driver movable portion in response to movement of the driver movable portion; and
an anchor fixed to the substrate and connected to the driver movable portion by an anchor flexure, the anchor flexure permitting the generally linear movement of the driver movable portion in the cross-track direction and preventing movement generally orthogonal to said cross-track direction.
2. The disk drive of claim 1 further comprising a driver flexure connecting the driver fixed portion to the driver end of the rod, the driver flexure substantially preventing movement of the driver end of the rod in the cross-track direction.
3. The disk drive of claim 1 wherein the anchor and anchor flexure are formed of electrically conductive material.
4. The disk drive of claim 1 wherein the radius from the axis of the post to the frame end of the rod is generally orthogonal to the generally linear displacement of the frame end of the rod.
5. The disk drive of claim 1 wherein the linear displacement of the frame end of the rod is between approximately 2 and 15 times greater than the linear displacement of the driver movable portion.
6. The disk drive of claim 1 further comprising a bonding platform attached to the rotatable frame, the head carrier being mounted to the bonding platform.
7. The disk drive of claim 1 wherein the head carrier is an air-bearing slider, the read/write head being formed on the slider.
8. A magnetic recording disk drive comprising:
a magnetic recording disk having a plurality of data tracks;
a read/write head for reading data from and writing data to the disk;
a head carrier for supporting the read/write head;
a primary actuator for coarse positioning the head to a selected track and comprising a primary actuator arm and a suspension attached to an end of the primary actuator arm;
a piezoelectric microactuator for fine positioning the head over the selected track, the microactuator comprising:
a substrate attached to the suspension;
a post fixed to the substrate;
a rotatable frame connected to the post by a plurality of torsional springs, the springs permitting rotary movement of the frame about an axis through the post, wherein the head carrier is attached to the rotatable frame;
a piezoelectric driver having a portion fixed to the substrate and a movable portion having bidirectional linear displacement;
a lever arm having its length aligned generally orthogonal to the linear displacement of the driver and having a driver end connected to the driver movable portion and a frame end connected to the rotatable frame at a radius from the axis of the post; and
a fulcrum attached to the substrate and spaced from the post and contacting the lever arm at a distance L 1 from the driver end and a distance L 2 from the frame end, wherein L 2 is greater than L 1 , whereby when the driver displaces the driver end of the lever arm the frame end of the lever arm exhibits a generally greater linear displacement.