Rotary piezoelectric microactuator and disk drive head-suspension assembly
View Patent ↗The invention is a moving-slider rotary piezoelectric microactuator as the secondary actuator for a dual-stage actuator disk drive. The microactuator has a substrate attached to the disk drive suspension and a rotatable frame that supports the slider, so the head-suspension assembly includes the suspension, the microactuator and the slider with attached read/write head. The rotatable frame 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 has a displacement amplification mechanism that includes a connecting rod and a linkage that translates the linear displacement of the driver to amplified orthogonal linear displacement of the rod. The connecting 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 rotary piezoelectric microactuator comprising:
a substrate;
a post fixed to the substrate;
a rotatable frame connected to the post by a plurality of post flexures, the post flexures permitting rotary movement of the frame about an axis through the post;
a single piezoelectric driver having a portion fixed to the substrate and a movable portion having bidirectional linear displacement along a first line;
a connecting rod having its length oriented generally orthogonal to said first line 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 said first line, 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 movable portion of the driver in response to movement of the movable portion of the driver;
an anchor fixed to the substrate and connected to the movable portion of the driver by an anchor flexure, the anchor flexure permitting the generally linear movement of the movable portion of the driver along said first line and preventing movement generally orthogonal to said first line; and
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 along said first line.
2. The microactuator of claim 1 wherein the anchor and anchor flexure are formed of electrically conductive material.
3. The microactuator 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.
4. The microactuator of claim 1 wherein the linear displacement of the second end of the rod is between approximately 2 and 15 times greater than the linear displacement of the movable portion of the driver.
5. The microactuator of claim 1 further comprising a magnetic recording disk drive head suspension, and wherein the substrate is attached to the suspension.
6. The microactuator of claim 1 further comprising a magnetic recording disk drive air-bearing slider, and wherein the slider is attached to the rotatable frame.
7. A magnetic recording head-suspension assembly comprising:
a magnetic recording disk drive suspension;
a magnetic recording disk drive head carrier, the carrier supporting a magnetic recording read/write head;
a piezoelectric 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.
8. The assembly of claim 7 further comprising a bonding platform attached to the rotatable frame, the head carrier being mounted to the bonding platform.