Belt-driven rotary cam elevator mechanism for reduced-head data storage device
An approach to a reduced-head hard disk drive involves an actuator subsystem that includes a ball screw cam assembly wherein the number of starts of a multi-start lead screw equals the number of balls riding in a corresponding start. A stepper motor may be employed to drive rotation of a pulley or gear to which a drive belt or drive chain is attached, to transmit power to the lead screw via the drive belt or chain, thereby driving rotation of the lead screw to drive translation of an actuator arm assembly along the axis of the lead screw so that a corresponding pair of read-write heads can access different magnetic-recording disks of a multiple-disk stack.
1. A hard disk drive (HDD) comprising:
a plurality of recording disk media rotatably mounted on a spindle;
a plurality of head sliders fewer in number than the plurality of disk media, each comprising a read-write transducer configured to read from and to write to at least two disk media of the plurality of disk media;
an actuator assembly configured to move the plurality of head sliders to access portions of the at least two disk media; and
an actuator elevator mechanism comprising:
a ball screw cam assembly comprising a screw and a driven feature,
a head-stack assembly (HSA) translatably coupled with the cam assembly,
a transmission element, operatively coupled with the driven feature and configured for transmitting power to the screw from a source positioned away from the screw,
a driving element configured for driving the transmission element, and
a motor coupled with the driving element and configured to drive rotation of the driving element to transmit power to the screw via the transmission element, to drive rotation of the screw to drive translation of the HSA along an axis of the screw.
2. The HDD of claim 1 , wherein:
the driven feature comprises a groove encircling the screw;
the transmission element comprises a drive belt, in part recessed in the groove of the screw; and
the driving element comprises a pulley configured for driving the drive belt.
3. The HDD of claim 1 , wherein:
the driven feature comprises a driven gear fixed to the screw;
the transmission element comprises a drive chain engaged with the driven gear of the screw; and
the driving element comprises a drive gear configured for driving the drive chain.
4. The HDD of claim 1 , wherein the driven feature of the screw is positioned near an end of the screw.
5. The HDD of claim 1 , wherein:
the actuator assembly comprises a voice coil motor (VCM) comprising an upper VCM plate; and
the motor of the actuator elevator mechanism is housed above the upper VCM plate.
6. The HDD of claim 5 , wherein:
the actuator elevator mechanism further comprises a support plate covering the cam assembly and the transmission element; and
the motor of the actuator elevator mechanism is coupled to the support plate.
7. The HDD of claim 1 , wherein the motor of the actuator elevator mechanism is a stepper motor.
8. The HDD of claim 1 , wherein the ball screw cam assembly comprises:
a hollow screw comprising at least three starts encircling the screw,
a ball bearing assembly comprising a same number of balls as starts, wherein each ball rides in a corresponding start, thereby forming a plane on which the balls ride perpendicular to the axis of the screw.
9. An actuator system for a reduced-head hard disk drive (HDD), the system comprising:
a ball screw cam assembly comprising a lead screw and a driven feature;
a head-stack assembly (HSA) translatably coupled with the cam assembly;
a transmission element, operatively coupled with the driven feature and configured for transmitting power to the lead screw from a source positioned away from the screw;
a driving element configured for driving the transmission element;
a drive shaft; and
a motor coupled with the driving element via the drive shaft and configured to drive rotation of the driving element to transmit power to the lead screw via the transmission element and the driven feature, to drive rotation of the lead screw to drive translation of the HSA along an axis of the lead screw.
10. The actuator system of claim 9 , wherein:
the driven feature comprises a groove encircling the lead screw;
the transmission element comprises a drive belt, in part recessed in the groove of the lead screw; and
the driving element comprises a pulley configured for driving the drive belt.
11. The actuator system of claim 9 , wherein:
the driven feature comprises a driven gear fixed to the lead screw;
the transmission element comprises a drive chain engaged with the driven gear of the lead screw; and
the driving element comprises a drive gear configured for driving the drive chain.
12. The actuator system of claim 9 , wherein the motor is a stepper motor.
13. The actuator system of claim 9 , wherein:
the lead screw comprises a hollow lead screw comprising at least three starts encircling the lead screw; and
the ball screw cam assembly further comprises a ball bearing assembly comprising a same number of balls as starts, wherein each ball rides in a corresponding start, thereby forming a plane on which the balls ride perpendicular to the axis of the lead screw.
14. A hard disk drive comprising the actuator system of claim 9 .
15. A method for translating a head-stack assembly (HSA) in a hard disk drive (HDD) to access multiple magnetic-recording disks, the method comprising:
driving a stepper motor mechanically coupled to a driving element with which a transmission element is movably coupled, thereby driving rotation of the driving element to transmit power to a multi-start lead screw via the transmission element and a driven feature of the lead screw, thereby driving rotation of the lead screw about a coaxial fixed shaft thereby driving translation of the HSA along an axis of the lead screw.
16. The method of claim 15 , wherein:
the driven feature comprises a groove encircling the lead screw;
the transmission element comprises a drive belt, in part recessed in the groove of the lead screw; and
the driving element comprises a pulley configured for driving the drive belt.
17. The method of claim 15 , wherein:
the driven feature comprises a driven gear fixed to the lead screw;
the transmission element comprises a drive chain engaged with the driven gear of the lead screw; and
the driving element comprises a drive gear configured for driving the drive chain.
18. The method of claim 15 , wherein driving the translation of the HSA includes vertically translating a planar multi-ball bearing assembly that is coupled with the HSA, by each of a particular number of balls of the bearing assembly riding in a corresponding respective start of the same particular number of starts of the multi-start screw.