# US 8,786,977 B2 · Induced transducer head vibration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,977 B2 - Document ID: US8786977B2 - Status: Granted - Kind: B2 - Application number: 13/274,186 - Filed: 2011-10-14 - Published: 2013-04-18 - Granted: 2014-07-22 - Earliest claimed: 2011-10-14 - Assignees: Seagate Technology LLC - Applicants: Dadi Setiadi; Stefan A. Weissner; David Gordon Qualey - Inventors: Dadi Setiadi; Stefan A. Weissner; David Gordon Qualey - Web page: https://patentgrep.com/patent/US8786977B2 ## CPC - G11B 5/607: {using thermal means} - G11B 5/6076: {Detecting head-disk contact} - 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 Vibration of a transducer slider can be used during slider fly height calibration to detect contact of the transducer slider with a disc surface. Amplification of the vibration may cause the transducer slider to tap the disc surface rather than drag across the disc surface when detecting contact with the disc surface. Amplification may be achieved by applying an in-phase AC signal to the transducer slider at the same frequency as the vibration of the slider. Reduced contact between the slider and the disc surface reduces wear on and the possibility of damage to the transducer slider and/or the disc surface. Once the fly height of the transducer slider is calibrated, the AC signal may be shifted out-of-phase with the slider vibration to dampen the slider vibration. ## Claims ### Claim 1 A system comprising: an actuator driver configured to create a protrusion on a transducer slider and amplify a vibration mode of the transducer slider to cause the protrusion to tap against a storage media. ### Claim 2 (depends on 1) The system of claim 1, wherein the vibration of the transducer slider is about an axis running through the transducer slider. ### Claim 3 (depends on 2) The system of claim 2, wherein the actuator driver is further configured to induce oscillation of the transducer slider about the axis at a resonant frequency of the vibration mode. ### Claim 4 (depends on 1) The system of claim 1, wherein the actuator driver is further configured to generate an AC signal in-phase with respect to the vibration mode of the transducer slider to amplify the vibration mode of the transducer slider. ### Claim 5 (depends on 4) The system of claim 4, further comprising: a phase lock loop configured to actively adjust the AC signal frequency and phase to equal the resonant frequency and phase of the vibration mode of the transducer slider. ### Claim 6 (depends on 1) The system of claim 1, wherein the actuator driver is further configured to generate an AC signal out-of-phase with respect to the vibration mode of the transducer slider to dampen the vibration mode of the transducer slider. ### Claim 7 (depends on 1) The system of claim 1, wherein the actuator driver is further configured to generate a DC signal increasing in magnitude over time that decreases fly height of the transducer slider. ### Claim 8 (depends on 1) The system of claim 1, further comprising: a contact detector configured to detect tapping contact between the protrusion and a storage disc. ### Claim 9 (depends on 1) The system of claim 1, further comprising: an electrometer configured to detect the frequency of the vibration mode of the transducer slider. ### Claim 10 (depends on 1) The system of claim 1, further comprising: a fly height actuator configured to move the transducer slider toward a storage disc until the protrusion is in tapping contact with the storage disc. ### Claim 11 (depends on 1) The system of claim 1, wherein the vibration mode of the transducer slider is a second pitch mode with a frequency ranging from 180 kHz to 250 Khz. ### Claim 12 (depends on 1) The system of claim 1, wherein the actuator driver further comprises: an AC actuator driver configured to amplify the vibration mode of the transducer slider; and a DC actuator driver configured to create the protrusion on the transducer slider. ### Claim 13 A method comprising: generating a signal to create a protrusion on a transducer slider; detecting a frequency of a vibration mode of the transducer slider; amplifying the vibration mode of the transducer slider to cause tapping contact between the protrusion and a storage disc; and detecting the tapping contact between the protrusion and the storage disc. ### Claim 14 (depends on 13) The method of claim 13, wherein the amplifying operation includes generating an AC signal oscillating at a resonant frequency of the detected vibration mode. ### Claim 15 (depends on 14) The method of claim 14, further comprising: eliminating the AC signal, responsive to the detecting tapping contact operation. ### Claim 16 (depends on 14) The method of claim 14, further comprising: shifting the AC signal out-of-phase with respect to the resonant frequency of the transducer slider to dampen the detected vibration mode of the transducer slider, responsive to the detecting tapping contact operation. ### Claim 17 (depends on 14) The method of claim 14, further comprising: adjusting the AC signal frequency and phase to equal the resonant frequency and phase of the vibration mode of the transducer slider. ### Claim 18 (depends on 13) The method of claim 13, wherein the generating operation generates a DC signal to a fly height actuator and the DC signal increases in magnitude and decreases fly height of the transducer slider over time, prior to the detecting tapping contact operation. ### Claim 19 (depends on 13) The method of claim 13, wherein the generating operation generates a DC signal to a fly height actuator and the DC signal is constant in magnitude over time and maintains a constant fly height of the transducer slider, responsive to the detecting tapping contact operation. ### Claim 20 (depends on 13) The method of claim 13, wherein the detecting the frequency of the vibration mode operation and the amplifying the vibration mode operation are performed iteratively. ### Claim 21 An actuator driver circuit comprising: a first branch with a non-inverting amplifier configured to output an AC signal oscillating at a resonant frequency of a transducer slider and amplify a detected vibration mode of the transducer slider; a second branch with an inverting amplifier configured to output an AC signal out-of-phase with respect to the resonant frequency of the transducer slider and dampen the detected vibration mode of the transducer slider; and a switch configured to select the first branch prior to detecting tapping contact between the transducer slider and a storage disc and select the second branch after detecting the tapping contact.