Flying height control method and circuit
A method of the present invention is used to control a flying height of a head operable to read data from and write data to a disk of a recording medium housed in an enclosure. In this method, the head is positioned to a predetermined radial measurement location on the disk to obtain error information on errors in the positioning of the head. A frequency analysis is performed on the obtained error information. Disturbance information on errors caused by a wind disturbance is calculated from the frequency analysis result. Pressure information on an air pressure in the enclosure is calculated based on the calculated disturbance information. A control value for controlling a flying height of the head with respect to the disk is determined based on the calculated pressure information. The flying height of the head is controlled based on the determined control value.
1. A method of controlling a flying height of a head operable to read data from and write data to a disk of a recording medium housed in an enclosure, the method comprising:
positioning the head to a predetermined radial measurement location on the disk;
obtaining error information on errors in the positioning of the head;
performing a frequency analysis on the obtained error information;
calculating disturbance information on errors caused by a wind disturbance from the frequency analysis result;
calculating pressure information on an air pressure in the enclosure based on the calculated disturbance information;
determining a control value for controlling a flying height of the head with respect to the disk based on the calculated pressure information; and
controlling the flying height of the head based on the determined control value.
2. The method as recited in claim 1 , wherein the calculating operation of the pressure information comprises excluding components that are in synchronism with rotation of the disk from the frequency analysis result.
3. The method as recited in claim 1 , wherein the calculating operation of the pressure information comprises calculating the pressure information from the error information and a sensitivity function indicating servo characteristics of the head.
4. The method as recited in claim 1 , wherein the calculating operation of the pressure information comprises extracting low-frequency components from the frequency analysis result to calculate the pressure information.
5. The method as recited in claim 4 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 0 Hz to 1,200 Hz from the frequency analysis result to calculate the pressure information.
6. The method as recited in claim 4 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 600 Hz to 1,200 Hz from the frequency analysis result to calculate the pressure information.
7. The method as recited in claim 4 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 600 Hz from the frequency analysis result to calculate the pressure information.
8. A flying height control circuit for controlling a flying height of a head operable to read data from and write data to a disk of a recording medium housed in an enclosure, the flying height control circuit comprising:
a head operation controller operable to move the head to a predetermined radial measurement location on the disk;
a disturbance estimation unit operable to obtain error information on errors in the positioning of the head moved by the head operation controller, to perform a frequency analysis on the obtained error information, and to calculate disturbance information on errors caused by a wind disturbance from the frequency analysis result;
an air pressure calculation unit operable to calculate pressure information on an air pressure in the enclosure based on the disturbance information calculated by the disturbance estimation unit; and
a control value management unit operable to determine a control value for controlling a flying height of the head with respect to the disk based on the pressure information calculated by the air pressure calculation unit.
9. The flying height control circuit as recited in claim 8 , wherein the calculating operation of the pressure information comprises excluding components that are in synchronism with rotation of the disk from the frequency analysis result.
10. The flying height control circuit as recited in claim 8 , wherein the calculating operation of the pressure information comprises calculating the pressure information from the error information and a sensitivity function indicating servo characteristics of the head.
11. The flying height control circuit as recited in claim 8 , wherein the calculating operation of the pressure information comprises extracting low-frequency components from the frequency analysis result to calculate the pressure information.
12. The flying height control circuit as recited in claim 11 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 0 Hz to 1,200 Hz from the frequency analysis result to calculate the pressure information.
13. The flying height control circuit as recited in claim 11 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 600 Hz to 1,200 Hz from the frequency analysis result to calculate the pressure information.
14. The flying height control circuit as recited in claim 11 , wherein the calculating operation of the pressure information comprises extracting components having frequencies of 600 Hz from the frequency analysis result to calculate the pressure information.
15. An information storage device comprising:
an enclosure accommodating a disk of a recording medium;
a head operable to read data from and write data to the disk;
a flying height control circuit for controlling a flying height of the head with respect to the disk, the flying height control circuit includes:
(i) a head operation controller operable to move the head to a predetermined radial measurement location on the disk,
(ii) a disturbance estimation unit operable to obtain error information on errors in the positioning of the head moved by the head operation controller, to perform a frequency analysis on the obtained error information; and to calculate disturbance information on errors caused by a wind disturbance from the frequency analysis result,
(iii) an air pressure calculation unit operable to calculate pressure information on an air pressure in the enclosure based on the disturbance information calculated by the disturbance estimation unit, and
(iv) a control value management unit operable to determine a control value for controlling a flying height of the head with respect to the disk based on the pressure information calculated by the air pressure calculation unit; and
a flying height adjustment unit operable to adjust the flying height of the head with respect to the disk based on the control value determined by the control value management unit.
16. The information storage device as recited in claim 15 , further comprising:
a verification determination unit operable to determine whether to verify data written to the disk based on the pressure information calculated by the air pressure calculation unit; and
a verification operation unit operable to verify data written to the disk based on the determination of the verification determination unit.
17. The information storage device as recited in claim 16 , wherein the flying height adjustment unit is operable to adjust the control value based on the verification result of the verification operation unit.