System and apparatus for reducing off-track gain for a disk drive actuator
View Patent ↗The dynamics of a disk drive actuator are enhanced by redistributing the mass and stiffness of the structure. The two nodal points of the second primary bending mode of the actuator are relocated to positions that are both radially outboard of their original positions. One nodal point is positioned as close to the read-write head as possible at one end of the actuator, and the other nodal point is positioned at the center of the active legs of the VCM coil at the other end of the actuator. This is done to reduce the off-track displacement associated with this fundamental resonance to near zero, allowing higher track densities to be supported.
1. A disk drive actuator assembly, comprising:
a comb having a pivot bore, a set of comb legs extending from the comb on one side of the pivot bore, and an arm extending from the comb opposite the active legs;
a pivot mounted in the pivot bore of the comb and having an axis of rotation;
a head gimbal assembly mounted to the arm of the comb and having a read/write head mounted on a distal end of the head gimbal assembly opposite the arm;
a coil for a voice coil motor mounted to the comb between the comb legs, the coil having a set of active legs;
a first nodal point of rotation of a second primary bending mode of the disk drive actuator assembly positioned adjacent the read/write head; and
a second nodal point of rotation of the second primary bending mode positioned at a geometric center of the active legs of the coil.
2. The disk drive actuator assembly of claim 1 , wherein the first nodal point is positioned as close to the read/write head as possible.
3. The disk drive actuator assembly of claim 1 , wherein, relative to the pivot axis, the first nodal point is positioned away from the axis several millimeters toward the read/write head.
4. The disk drive actuator assembly of claim 1 , wherein, relative to the pivot axis, the second nodal point is positioned away from the axis several millimeters to the geometric center of the active legs of the coil.
5. A disk drive, comprising:
an enclosure;
a disk rotatably mounted to the enclosure and having a magnetic media; and
an actuator assembly, comprising:
a comb having a pivot bore, comb legs extending from the comb on one side of the pivot bore, and an arm extending from the comb opposite the active legs;
a pivot mounted in the pivot bore of the comb and having an axis of rotation;
a head gimbal assembly mounted to the arm of the comb and having a read/write head;
a coil for a voice coil motor mounted to the comb between the comb legs, the coil having a set of active legs;
a first nodal point of rotation of a second primary bending mode of the disk drive actuator assembly positioned adjacent the read/write head; and
a second nodal point of rotation of the second primary bending mode positioned at a geometric center of the active legs of the coil.
6. The disk drive of claim 5 , wherein the first nodal point is positioned as close to the read/write head as possible.
7. The disk drive of claim 5 , wherein, relative to the pivot axis, the first nodal point is positioned away from the axis several millimeters toward the read/write head.
8. The disk drive of claim 5 , wherein, relative to the pivot axis, the second nodal point is positioned away from the axis several millimeters to the geometric center of the active legs of the coil.