Disk drive having a head loading/unloading ramp that includes a torsionally-compliant member
View Patent ↗A disk drive includes a ramp having a fixed portion that is fixed to the disk drive base, and a guide portion that is not. The guide portion includes a guide surface having a parking region that is in contact with an HGA lift-tab with the disk drive in a non-operational state. The guide surface also has a load/unload region that extends over a disk outer periphery. The guide surface defines a guide surface length that is measured from the parking region to the load/unload region. The ramp also includes a torsionally-compliant member connecting the fixed portion to the guide portion. A distance between the torsionally-compliant member and the parking region, measured approximately parallel to the guide surface length, is less than half the guide surface length. The guide portion is not connected to the fixed portion over at least two-thirds of the guide surface length.
1. A disk drive comprising:
a disk drive base;
a spindle attached to the disk drive base;
a disk attached to the spindle, the disk including a disk outer periphery;
an actuator attached to the disk drive base;
a head gimbal assembly (HGA) attached to the actuator, the HGA including a lift-tab; and
a ramp including:
a fixed portion that is fixed to the disk drive base;
a guide portion that is not fixed to the disk drive base, the guide portion including a guide surface having a parking region that is in contact with the lift-tab with the disk drive in a non-operational state, the guide surface also having a load/unload region that extends over the disk outer periphery, the guide surface defining a guide surface length that is measured from the parking region to the load/unload region; and
a torsionally-compliant member connecting the fixed portion to the guide portion, a distance between the torsionally-compliant member and the parking region measured approximately parallel to the guide surface length being less than half the guide surface length;
wherein the guide portion is not connected to the fixed portion over at least two-thirds of the guide surface length, and
wherein the fixed portion includes at least one limiter surface that is disposed to be contacted by the guide portion if a maximum torsional deflection of the guide portion is exceeded.
2. The disk drive of claim 1 wherein the spindle defines a spindle axis of rotation, and wherein the torsionally-compliant member has a torsional stiffness that is high enough for the guide portion to resist deflection of the load/unload region parallel to the spindle axis of rotation by at least 5 kN/m, but wherein the torsional stiffness of the torsionally-compliant member is low enough for the guide portion to resist deflection of the load/unload region parallel to the spindle axis of rotation by no more than 25 kN/m.
3. The disk drive of claim 2 further comprising a positioning member attached to the fixed portion and attached to the guide portion, the positioning member having a torsional stiffness that is less than one-fifth the torsional stiffness of the torsionally-compliant member.
4. The disk drive of claim 3 wherein the fixed portion, the guide portion, the torsionally-compliant member, and the positioning member are a single component with material continuity rather than being an assembly of subcomponents.
5. The disk drive of claim 1 wherein the guide surface is one of a plurality of guide surfaces on the guide portion.
6. The disk drive of claim 1 , wherein the spindle defines a spindle axis of rotation, and wherein a maximum deflection of the load/unload region of the guide portion measured parallel to the spindle axis of rotation is at least 100 microns.
7. The disk drive of claim 1 wherein the limiter surface is a surface of a projection extending from the fixed portion into a hole in the guide portion, the hole being larger than the projection by a clearance that is at least 50 microns.
8. The disk drive of claim 1 wherein the guide portion is not connected to the fixed portion over at least three-fourths of the guide surface length.
9. The disk drive of claim 1 wherein the distance between the torsionally-compliant member and the parking region is less than one-fourth of the guide surface length.
10. The disk drive of claim 1 wherein the distance between the torsionally-compliant member and the parking region measured approximately parallel to the guide surface length is less than 5 mm.
11. The disk drive of claim 1 wherein the ramp comprises a material selected from the group consisting of polyoxymethylene, polycarbonate, polyetherimide, liquid crystal polymer, nylon, and acetyl resin plastic.
12. The disk drive of claim 11 wherein the fixed portion, the guide portion, and the torsionally-compliant member are a single component with material continuity rather than being an assembly of subcomponents.
13. The disk drive of claim 1 wherein the ramp material has a Young's modulus between 1.0 GPa to 6 G Pa.
14. The disk drive of claim 1 wherein the torsionally-compliant member comprises a torsional beam.
15. The disk drive of claim 12 wherein the torsionally-compliant member has a total cross sectional area in the range 2 mm 2 to 9 mm 2 .
16. The disk drive of claim 1 wherein the torsionally-compliant member comprises a plurality of beams, bending of which permits torsion of the guide portion relative to the fixed portion.