Method for determining a microactuator range of movement
View Patent ↗A spin stand testing system is used to determine a positioning range of a microactuator disposed on a head gimbal assembly. The microactuator is configured to laterally translate a read sensor of a head of the head gimbal assembly through the positioning range. The spin stand testing system includes a disk having a track, and a secondary mover configured to laterally translate the head gimbal assembly. During testing, a feedback loop keeps the read sensor locked to the track. While the read sensor remains locked, the head gimbal assembly is translated laterally. The microactuator translates the read sensor in an opposite direction until the microactuator reaches an end of its range, which is determined by monitoring a signal. The amount of translation of the head gimbal assembly by the secondary mover when the signal indicates the end of the range is the measured positioning range in one direction.
1. A method for using a spin stand testing system to measure a positioning range of a microactuator of a head gimbal assembly, the microactuator being configured to translate a read sensor of a head of the head gimbal assembly, the method comprising:
locking the read sensor to a track on a disk of the spin stand testing system, and
monitoring a signal while translating the head gimbal assembly in a first direction until the signal deviates from a constant by more than a first threshold value, whereby an amount of translation of the head gimbal assembly, measured from when the read sensor is locked until the signal deviates from the constant by more than the threshold value, correlates to the positioning range of the microactuator.
2. The method of claim 1 wherein locking the read sensor to the track includes using a feedback loop.
3. The method of claim 2 wherein the feedback loop comprises a closed-loop servo.
4. The method of claim 1 wherein locking the read sensor to the track includes reading a two-frequency burst.
5. The method of claim 4 wherein the two-frequency burst is continuous around the track.
6. The method of claim 1 wherein locking the read sensor to the track includes controlling the microactuator to translate the read sensor in response to a difference between a read signal and a set point.
7. The method of claim 1 wherein monitoring the signal includes monitoring a derivative of a voltage applied to the microactuator.
8. The method of claim 1 wherein monitoring the signal includes monitoring a position error signal.
9. The method of claim 1 further comprising determining the positioning range of the microactuator as equal to a distance of translation of the head gimbal assembly in the first direction when the signal deviates from the constant by more than the first threshold value.
10. The method of claim 9 further comprising
locking the read sensor to the track, and
monitoring the signal while translating the head gimbal assembly in a second direction opposite to the first direction until the signal deviates from the constant by more than a second threshold value.
11. The method of claim 10 wherein the first and second threshold values are about the same.
12. The method of claim 10 further comprising determining a total positioning range of the microactuator as equal to a distance of translation of the head gimbal assembly in the first direction when the signal deviates from the constant by more than the first threshold value plus a distance of translation of the head gimbal assembly in the second direction when the signal deviates from the constant by more than the second threshold value.
13. A method for using a spin stand testing system to measure a positioning range of a microactuator of a head gimbal assembly, the microactuator being configured to translate a read sensor of a head of the head gimbal assembly, the method comprising:
locking the read sensor to a track on a disk of the spin stand testing system with a closed-loop servo, and
monitoring a position error signal while translating the head gimbal assembly until the position error signal deviates from a constant by more than a threshold value.
14. The method of claim 13 wherein locking the read sensor to the track includes reading a two-frequency burst.