# US 2018/0322904 A1 · Detecting media defects > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0322904 A1 - Document ID: US20180322904A1 - Status: Published application - Kind: A1 - Application number: 16/020,909 - Filed: 2018-06-27 - Published: 2018-11-08 - Earliest claimed: 2016-10-11 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Robert G. Biskeborn; Edwin R. Childers; Jason Liang - Web page: https://patentgrep.com/patent/US20180322904A1 ## CPC - G11B 20/1816: {Testing} - G11B 5/00813: {magnetic tapes} - G11B 5/3133: {including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure (G11B5/3106 takes precedence)} - G11B 5/00826: {comprising a plurality of single poles or gaps or groups thereof operative at the same time} - G11B 5/584: for track following on tapes - G11B 2020/1826: {wherein a defect list or error map is generated} - 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 computer program product, according to one embodiment, includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. Moreover, the program instructions are executable by a controller to cause the controller to: detect, by the controller, a change in a resistance value of at least one of a plurality of detector structures, for identifying a defect on a magnetic medium. Each of the detector structures includes a pair of conductive layers separated by an insulating material. Moreover, none of the detector structures include an operable reader for reading data from a magnetic medium. Other systems, methods, and computer program products are described in additional embodiments. ## Claims ### Claim 1 A computer program product comprising a computer readable storage medium having program instructions embodied therewith, wherein the computer readable storage medium is not a transitory signal per se, the program instructions executable by a controller to cause the controller to: detect, by the controller, a change in a resistance value of at least one of a plurality of detector structures, for identifying a defect on a magnetic medium, wherein each of the detector structures includes a pair of conductive layers separated by an insulating material, with a proviso that none of the detector structures include an operable reader for reading data from a magnetic medium. ### Claim 2 (depends on 1) The computer program product of claim 1, wherein the program instructions are executable by a controller to cause the controller to: use, by the controller, a servo reader to determine a position along a length of the magnetic medium that corresponds to an identified defect. ### Claim 3 (depends on 1) The computer program product of claim 1, wherein the program instructions are executable by a controller to cause the controller to: cause, by the controller, a plurality of write transducers to write in response to detecting the change in resistance value. ### Claim 4 (depends on 1) The computer program product of claim 1, wherein a distance separating the conductive layers of each of the detector structures, measured in an intended direction of magnetic media travel, is in a range of from about 2 nm to about 10 nm. ### Claim 5 (depends on 1) The computer program product of claim 1, wherein the insulating material is the only layer positioned between the conductive layers in each of the detector structures. ### Claim 6 (depends on 1) The computer program product of claim 1, wherein the program instructions are executable by a controller to cause the controller to: cause, by the controller, at least one write transducer to write a signal burst on a magnetic medium at about a position of an identified defect along a length of the magnetic medium. ### Claim 7 (depends on 1) The computer program product of claim 1, wherein the program instructions are executable by a controller to cause the controller to: evaluate, by the controller, a number of identified defects per unit surface area of a magnetic tape to determine a quality of the magnetic tape. ### Claim 8 (depends on 1) The computer program product of claim 1, wherein the plurality of detector structures are positioned in an array, wherein a width of the array of detector structures is wider in a cross-track direction than an array of the at least one write transducer. ### Claim 9 (depends on 1) The computer program product of claim 1, wherein the insulating material includes a laminate of layers. ### Claim 10 (depends on 1) The computer program product of claim 1, wherein each of the detector structures includes a resistor associated therewith, wherein each resistor couples the respective pair of conductive layers together. ### Claim 11 A computer-implemented method, comprising: detecting a change in a resistance value of at least one of a plurality of detector structures for identifying an approximate location of a defect on a magnetic medium, wherein each of the detector structures includes a pair of conductive layers separated by an insulating material, with a proviso that none of the detector structures include an operable reader for reading data from a magnetic medium. ### Claim 12 (depends on 11) The computer-implemented method of claim 11, comprising: evaluating a number of identified defects per unit surface area of a magnetic tape to determine a quality of the magnetic tape. ### Claim 13 (depends on 11) The computer-implemented method of claim 11, wherein a distance separating the conductive layers of each of the detector structures, measured in an intended direction of magnetic media travel, is in a range of from about 2 nm to about 10 nm. ### Claim 14 (depends on 11) The computer-implemented method of claim 11, wherein the insulating material is the only layer positioned between the conductive layers in each of the detector structures. ### Claim 15 (depends on 11) The computer-implemented method of claim 11, wherein the insulating material includes a laminate of layers. ### Claim 16 (depends on 11) The computer-implemented method of claim 11, wherein each of the detector structures includes a resistor associated therewith, wherein each resistor couples the respective pair of conductive layers together. ### Claim 17 (depends on 11) The computer-implemented method of claim 11, comprising: using a servo reader to determine a position along a length of the magnetic medium that corresponds to an identified defect. ### Claim 18 (depends on 11) The computer-implemented method of claim 11, comprising: using at least one write transducer to write a signal burst on a magnetic medium at about a position of an identified defect along a length of the magnetic medium. ### Claim 19 (depends on 18) The computer-implemented method of claim 18, wherein the plurality of detector structures are positioned in an array, wherein a width of the array of detector structures is wider in a cross-track direction than an array of the at least one write transducer.