Method and apparatus for characterizing the microwaviness of a disk surface
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsNone recorded
Life of this patent
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Abstract
The microwaviness (i.e., surface waviness for wavelengths on the order of the length of the transducing head) of a recording disk surface is measured during manufacture as a quality control process. Preferably, the disk is measured using an actuator-mounted thermal sensor, comprising an electrical resistance element driven with a constant current. At small distances, the disk surface acts as a heat sink and variation in this distance will be detected as a change in resistance of the sensor. Preferably the sensor is initially used to characterize the gross waviness of the surface, and the actuator then follows this gross waviness to measure surface variations in the microwaviness range.
Claims13
A method for manufacturing a disk for a rotating disk drive data storage device, comprising the steps of:
- forming a disk for use in a disk drive data storage device, said disk having at least one data recording surface;
- characterizing microwaviness of said data recording surface of said disk by mounting said disk in a test fixture for characterizing microwaviness;
- characterizing warp of said disk with a sensor that is mounted to a carriage, the carriage being positionable along both an r-axis and a z-axis, the r-axis extending radially from a rotational axis of the disk, and the z-axis being perpendicular to said data recording surface;
- simultaneously rotating said disk and moving the carriage and the sensor relative to the z-axis to maintain a substantially constant distance between said sensor and said data recording surface, and relative to the r-axis;
- and
- characterizing microwaviness of said data recording surface using said sensor, while performing said step of simultaneously rotating said disk and moving the carriage and the sensor;
- and
- rejecting said disk for use in a disk drive data storage device if said microwaviness exceeds a pre-determined limit.
A method for characterizing a disk surface of a disk for a disk drive data storage device, comprising the steps of:
- rotatably mounting said disk in a measurement fixture, said measurement fixture having a sensor positionable in a z-axis, said z-axis being perpendicular to said disk surface, said sensor being capable of measuring a distance between the sensor and a disk surface;
- characterizing warp of said disk with said sensor at a plurality of circumferentially spaced locations of said disk;
- simultaneously rotating said disk and moving said sensor in said z-axis to maintain a substantially constant distance between said sensor and said disk surface;
- and
- characterizing microwaviness of said disk surface using said sensor, while performing said step of simultaneously rotating said disk and moving said sensor in said z-axis.
An apparatus for characterizing a disk surface of a disk for a disk drive data storage device, comprising:
- a rotatable disk mounting driven by a spin motor, said rotatable disk mounting receiving a disk to be characterized;
- a frame having a movable suspension with a carriage mounted thereto, and a z-axis actuator for moving the carriage linearly alone a z-axis that is perpendicular to the disk surface to maintain a substantially constant distance between said sensor and said disk surface;
- a sensor mounted to the carriage and positionable along the z-axis with the carriage, said sensor being capable of measuring a distance between the sensor and the disk surface;
- a control program which simultaneously rotates said disk using said spin motor and moves the carriage and sensor relative to the z-axis while characterizing microwaviness of said disk surface using said sensor.
Dependencies are inferred from the claim text.