# US 8,786,976 B1 · Disk drive detecting when head is on ramp > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,976 B1 - Document ID: US8786976B1 - Status: Granted - Kind: B1 - Application number: 13/237,727 - Filed: 2011-09-20 - Granted: 2014-07-22 - Earliest claimed: 2011-09-20 - Assignees: Western Digital Technologies, Inc. - Applicants: Soo-Choon Kang; Siri S. Weerasooriya; Scott A. Ottele - Inventors: Soo-Choon Kang; Siri S. Weerasooriya; Scott A. Ottele - Web page: https://patentgrep.com/patent/US8786976B1 ## CPC - G11B 21/12: Raising and lowering; Back-spacing or forward-spacing along track; Returning to starting position {otherwise than during transducing operation} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a fly height actuator for controlling a fly height of the head, and a ramp for parking the head. A ramp procedure is executed by applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal, and detecting whether the head is on the ramp in response to the fly height signal. ## Claims ### Claim 1 A disk drive comprising: a disk surface; a head actuated over the disk surface, the head comprising a fly height actuator for controlling a fly height of the head; a ramp for parking the head; and control circuitry operable to execute a ramp procedure by: applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal; seeking the head toward the outer diameter of the disk surface; and detecting when the head contacts the ramp in response to the fly height signal. ### Claim 2 (depends on 1) The disk drive as recited in claim 1, wherein the head comprises a fly height sensor operable to generate the fly height signal. ### Claim 3 (depends on 1) The disk drive as recited in claim 1, wherein the head comprises a read element operable to read data from the disk and operable to generate the fly height signal. ### Claim 4 (depends on 1) The disk drive as recited in claim 1, wherein the control circuitry is further operable to decrease the fly height of the head as the head approaches the ramp during the seek. ### Claim 5 (depends on 4) The disk drive as recited in claim 4, wherein the control circuitry is further operable to decrease the fly height of the head to a level lower than a fly height used to execute one of a normal write and read operation. ### Claim 6 (depends on 1) The disk drive as recited in claim 1, wherein the control circuitry is further operable to detect when the head contacts the ramp when the fly height signal indicates the fly height exceeds a fly height threshold. ### Claim 7 (depends on 6) The disk drive as recited in claim 6, wherein the control circuitry is further operable to: calibrate a touchdown value for the control signal that causes the head to contact the disk surface; and adjust the control signal to be substantially less than the touchdown value and calibrate the fly height threshold in response to the fly height signal. ### Claim 8 (depends on 1) The disk drive as recited in claim 1, wherein: the disk drive comprises a plurality of disk surfaces and a plurality of heads; the control circuitry is further operable to: calibrate a touchdown value for the control signal that causes each head to contact the respective disk surface; and execute the ramp procedure using the head having the maximum touchdown value. ### Claim 9 A method of operating a disk drive, the disk drive comprising a disk surface, a head actuated over the disk surface, the head comprising a fly height actuator for controlling a fly height of the head, a ramp for parking the head, the method comprising: applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal; seeking the head toward the outer diameter of the disk surface; and detecting when the head contacts the ramp in response to the fly height signal. ### Claim 10 (depends on 9) The method as recited in claim 9, wherein the head comprises a fly height sensor operable to generate the fly height signal. ### Claim 11 (depends on 9) The method as recited in claim 9, wherein the head comprises a read element operable to read data from the disk and operable to generate the fly height signal. ### Claim 12 (depends on 9) The method as recited in claim 9, further comprising decreasing the fly height of the head as the head approaches the ramp during the seek. ### Claim 13 (depends on 12) The method as recited in claim 12, further comprising decreasing the fly height of the head to a level lower than a fly height used to execute one of a normal write and read operation. ### Claim 14 (depends on 9) The method as recited in claim 9, further comprising detecting when the head contacts the ramp when the fly height signal indicates the fly height exceeds a fly height threshold. ### Claim 15 (depends on 14) The method as recited in claim 14, further comprising: calibrating a touchdown value for the control signal that causes the head to contact the disk surface; and adjusting the control signal to be substantially less than the touchdown value and calibrate the fly height threshold in response to the fly height signal. ### Claim 16 (depends on 9) The method as recited in claim 9, wherein: the disk drive comprises a plurality of disk surfaces and a plurality of heads; the method further comprises: calibrating a touchdown value for the control signal that causes each head to contact the respective disk surface; and executing the ramp procedure using the head having the maximum touchdown value. ### Claim 17 A disk drive comprising: a plurality of disk surfaces; a head actuated over each disk surface, the head comprising a fly height actuator for controlling a fly height of the head in response to a control signal; a ramp for parking the heads; and control circuitry operable to: calibrate a touchdown value for the control signal that causes each head to contact the respective disk surface; and execute a ramp procedure using the head having the maximum touchdown value by: applying the control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal; and detecting whether the head is on the ramp in response to the fly height signal. ### Claim 18 A method of operating a disk drive, the method comprising: calibrating a touchdown value for a control signal of a fly height actuator that causes each of a plurality of heads to contact a respective disk surface; and executing a ramp procedure using the head having the maximum touchdown value by: applying the control signal to the fly height actuator to decrease the fly height of the head and receiving a corresponding fly height signal; and detecting whether the head is on the ramp in response to the fly height signal.