Control device, magnetic tape system, control method, and program

Abstract

The control device performs TDS influence reduction control for reducing the influence of TDS of the magnetic tape. The TDS influence reduction control is control that reduces the influence by equalizing 3 or more difference absolute values obtained for 3 or more reading elements in a case where 3 or more servo bands are read in parallel by 3 or more reading elements arranged in a linear shape. The difference absolute value is an absolute value of a difference between a current position of a reading element and a target reading position of the reading element.

Description

Technical Field

[0001] This invention relates to a control device, magnetic tape system, control method, and program. Background Technology

[0002] To increase the speed at which data is recorded on or played back on magnetic tape using magnetic heads (i.e., the data transfer speed), it is necessary to increase the number of magnetic elements mounted on the magnetic heads (i.e., the number of magnetic elements that record or play back data on or from magnetic tape in parallel).

[0003] Previously, when adding magnetic components, the number of magnetic components was increased to accommodate the increased number of existing servo read elements (i.e., magnetic components that read servo patterns) within the spacing between them, in order to record and play back data for a single data band. In other words, the spacing between magnetic components was narrowed. However, narrower spacing between magnetic components increases the likelihood of crosstalk problems, layout issues within the read / write head, and wiring problems.

[0004] As a technology for solving this problem, U.S. Patent Application Publication No. 2021 / 0110847 discloses a technology that can increase the data transmission rate by using a magnetic head capable of recording data in parallel to or playing back data in parallel from multiple data tapes formed on a magnetic tape, without reducing the spacing between magnetic elements within the magnetic head.

[0005] On the other hand, because magnetic tapes are made of thin film materials, they expand and contract in the width direction. This is caused by the storage conditions of the tape containing the data (e.g., storage time, temperature, and humidity), the tension applied to the tape during data recording or playback, and the environment in which the tape is used (e.g., temperature and humidity). As the tape expands and contracts in the width direction, the positions of the magnetic elements and data tracks within the magnetic head change, making it difficult to play back data at the accurate position.

[0006] As a technology for solving this problem, Japanese Patent Application Publication No. 2009-123288 discloses a technique for aligning each magnetic element with each data track by tilting the magnetic head. Furthermore, the same technique is also disclosed in Japanese Patent Application Publication No. 2023-017681. Summary of the Invention

[0007] When applying the technology described in Japanese Patent Application Publication No. 2009-123288 to the system described in U.S. Patent Application Publication No. 2021 / 0110847, if the deformation amount (i.e., the deformation amount in the width direction of the magnetic tape) of each data tape of the magnetic tape is the same, the magnetic element in the magnetic head can be aligned with the track at an accurate position on the magnetic tape.

[0008] However, if the amount of deformation between data tapes is different, and the difference in deformation between data tapes is too large, even if the magnetic head is tilted, the error of the servo pattern signal obtained by the servo reading element in the magnetic head reading the servo pattern of the magnetic tape will increase, or the error between the position of the data recorded on the magnetic tape and the playback magnetic element (e.g., the magnetic element used for playback data) in the magnetic head will increase. Therefore, it may be impossible to accurately play back the data on the magnetic tape.

[0009] One embodiment of the present invention provides a control device, magnetic tape system, control method, and program that can help improve the accuracy of playing back data recorded on magnetic tape.

[0010] The first aspect of the present invention is a control device comprising a processor that performs TDS reduction control to reduce the TDS of a magnetic tape. The magnetic tape has three or more servo tapes arranged along its width direction, each servo tape recording multiple servo patterns along its length direction, and data tapes formed between the three or more servo tapes in the width direction. The TDS reduction control is performed by equalizing the absolute values ​​of three or more differences obtained for the three or more read elements in the arrangement direction of the three or more read elements when the three or more read elements are read in parallel by means of three or more read elements arranged in a straight line. The absolute value of the difference is the absolute value of the difference between the current position of the read element and the target read position of the read element.

[0011] The second aspect of the present invention is the control device involved in the first aspect, wherein the TDS impact reduction control is a control that equalizes the absolute values ​​of three or more differences through servo control.

[0012] The third aspect of the present invention is a magnetic tape system comprising: a control device as described in the first or second aspect; and a magnetic head for recording data on the magnetic tape and / or playing back data recorded on the magnetic tape.

[0013] The fourth aspect of the present invention is the magnetic tape system of the third aspect, which includes a magnetic tape.

[0014] The fifth aspect of this invention is a control method comprising the following steps: performing TDS impact reduction control to reduce the impact of TDS on a magnetic tape, wherein the magnetic tape has three or more servo tapes arranged along the width direction, each of the three or more servo tapes recording multiple servo patterns along the length direction, and data tapes are formed between the three or more servo tapes in the width direction. The TDS impact reduction control is performed by equalizing the absolute values ​​of the differences obtained for the three or more read elements when the three or more read elements are read in parallel by three or more read elements arranged in a straight line, wherein the absolute value of the difference is the absolute value of the difference between the current position of the read element and the target read position of the read element.

[0015] The sixth aspect of this invention is a program for causing a computer to perform processing, the processing including the following steps: performing TDS impact reduction control to reduce the impact of TDS on a magnetic tape, wherein three or more servo tapes are arranged along the width direction, each of the three or more servo tapes records multiple servo patterns along the length direction, and data tapes are formed between the three or more servo tapes in the width direction, the TDS impact reduction control is as follows: the impact is reduced by equalizing the absolute values ​​of three or more differences obtained for the three or more read elements in the arrangement direction of the three or more read elements when the three or more read elements are read in parallel by reading the three or more servo tapes arranged in a straight line, the absolute value of the difference between the current position of the read element and the target read position of the read element. Attached Figure Description

[0016] Figure 1 This is a block diagram illustrating an example of the structure of a magnetic tape system.

[0017] Figure 2 This is a schematic perspective view showing an example of the appearance of a cassette tape cassette.

[0018] Figure 3 This is a schematic diagram illustrating an example of the hardware structure of a magnetic tape drive.

[0019] Figure 4 This is a schematic perspective view illustrating an example of how a magnetic field is released from the underside of a magnetic tape cassette via a contactless reader / writer.

[0020] Figure 5 This is a schematic diagram illustrating an example of the hardware structure of a magnetic tape drive.

[0021] Figure 6 This is a conceptual diagram illustrating an example of how the magnetic head is positioned on the magnetic tape when viewed from the surface side.

[0022] Figure 7This is a conceptual diagram illustrating an example of the structure of a data tape formed on the surface of a magnetic tape.

[0023] Figure 8 This is a conceptual diagram illustrating an example of the correspondence between data recording and playback elements and data tracks.

[0024] Figure 9 This is a conceptual diagram illustrating an example of how a servo pattern is read by a servo reading element.

[0025] Figure 10 This is a conceptual diagram illustrating an example of how the width of a magnetic tape is viewed from the surface side before and after it shrinks.

[0026] Figure 11 This is a conceptual diagram illustrating an example of how the magnetic head is tilted when viewed from the surface side of the magnetic tape.

[0027] Figure 12A This is a conceptual diagram illustrating an example of a data track formed by recording data on the surface of a magnetic tape in an SMR manner on the upper side of the tape in the width direction (between servo tape SB2 and servo tape SB3 within the surface of the tape), with multiple segmented data tracks offset and overlapping along the second direction.

[0028] Figure 12B This is a conceptual diagram illustrating an example of a data track formed by recording data on the surface of a magnetic tape in an SMR manner on the lower side in the width direction (between servo tape SB1 and servo tape SB2 within the surface of the magnetic tape), where multiple segmented data tracks are staggered and overlapped along the second direction.

[0029] Figure 13 This is a conceptual diagram illustrating an example of how the first recording module, playback module, and second recording module are arranged on the magnetic head.

[0030] Figure 14 This is a conceptual diagram illustrating an example of how the magnetic head on a magnetic tape with multiple data bands of varying lengths in the width direction is tilted when viewed from the surface side of the magnetic tape.

[0031] Figure 15 This is a diagram illustrating an example of the pre-storage and post-storage functions, which represent the correlation between the reading position of the servo read element relative to the servo tape and the distance of the servo tape.

[0032] Figure 16 This is a conceptual diagram representing an example of a process where a processing device creates a linear function.

[0033] Figure 17This is a conceptual diagram illustrating an example of a processing device that creates an adjusted linear function by fitting a linear function to a stored function.

[0034] Figure 18 This is a conceptual diagram used to illustrate the variables used in equation (4) to determine the current position of the servo read element SR when the magnetic tape MT is traveling in the forward direction.

[0035] Figure 19 This is a conceptual diagram illustrating an example of a processing device that uses formulas to calculate tilt angle, tension, and displacement, and performs skew control based on the calculated tilt angle, tension control based on the calculated tension, and displacement control based on the calculated displacement.

[0036] Figure 20 This is a flowchart illustrating an example of a process where the TDS effect performed by the processing device reduces the processing efficiency.

[0037] Figure 21 This is a conceptual diagram representing a modified example of a magnetic tape and magnetic head.

[0038] Figure 22 This is a conceptual diagram illustrating how a program stored in a computer-readable and non-temporary storage medium is installed on a computer. Detailed Implementation

[0039] Hereinafter, an example of an implementation of the control device, magnetic tape system, control method, and program involved in the present invention will be described with reference to the accompanying drawings.

[0040] First, let's explain the statements used in the following description.

[0041] CPU stands for Central Processing Unit. RAM stands for Random Access Memory. NVM stands for Non-volatile memory. EEPROM stands for Electrically Erasable and Programmable Read Only Memory. SSD stands for Solid State Drive. HDD stands for Hard Disk Drive. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field-Programmable Gate Array. PLC stands for Programmable Logic Controller. SoC stands for System on a Chip. IC stands for Integrated Circuit. RFID stands for Radio Frequency Identifier. UI stands for "User Interface". WAN stands for "Wide Area Network". LAN stands for "Local Area Network". TDS stands for "Transverse Dimensional Stability". SMR stands for "Shingled Magnetic Recording". PES stands for "Position Error Signal".

[0042] As an example, such as Figure 1 As shown, the magnetic tape system 10 includes a magnetic tape cassette 12 and a magnetic tape drive 14. The magnetic tape cassette 12 is loaded into the magnetic tape drive 14. The magnetic tape cassette 12 contains a magnetic tape MT. The magnetic tape drive 14 pulls out the magnetic tape MT from the loaded magnetic tape cassette 12, and while driving the pulled-out magnetic tape MT, records data on the magnetic tape MT or reads data from the magnetic tape MT.

[0043] In this embodiment, the magnetic tape MT is an example of a "magnetic tape" according to the present invention. Furthermore, in this embodiment, the magnetic tape drive 14 is an example of a "control device" according to the present invention. And, in this embodiment, the magnetic tape system 10 is an example of a "magnetic tape system" according to the present invention.

[0044] Next, refer to Figures 2-5 An example of the structure of the magnetic tape cassette 12 will be described. Furthermore, in the following description, for ease of explanation, [the following text is omitted as it is not part of the original description]. Figures 2-5 In the diagram, arrow A indicates the direction in which the tape cassette 12 is loaded into the tape drive 14. Arrow A is defined as the front direction of the tape cassette 12, and the front side of the tape cassette 12 is defined as the front side of the tape cassette 12. In the following description of the structure, "front" refers to the front side of the tape cassette 12.

[0045] Furthermore, in the following description, for ease of explanation, Figures 2-5 In the following description of the structure, arrow B, which is orthogonal to arrow A, is defined as the right direction, and the right side of tape cassette 12 is defined as the right side of tape cassette 12. In the following description of the structure, "right" refers to the right side of tape cassette 12.

[0046] Furthermore, in the following description, for ease of explanation, Figures 2-5 In the following description of the structure, the direction opposite to that of arrow B is defined as the left direction, and the left side of tape cassette 12 is defined as the left side of tape cassette 12. In the following description of the structure, "left" refers to the left side of tape cassette 12.

[0047] Furthermore, in the following description, for ease of explanation, Figures 2-5 In the diagram, arrow C represents the direction orthogonal to both arrow A and arrow B. Arrow C is defined as the upward direction of tape cassette 12, and the upward side of tape cassette 12 is defined as the upper side of tape cassette 12. In the following description of the structure, "upper" refers to the upper side of tape cassette 12.

[0048] Furthermore, in the following description, for ease of explanation, Figures 2-5 In this design, the direction opposite to the front direction of the tape cassette 12 is defined as the rear direction of the tape cassette 12, and the rear side of the tape cassette 12 is defined as the rear side of the tape cassette 12. In the following description of the structure, "rear" refers to the rear side of the tape cassette 12.

[0049] Furthermore, in the following description, for ease of explanation, Figures 2-5 In this design, the direction opposite to the upward direction of the tape cassette 12 is defined as the downward direction of the tape cassette 12, and the downward side of the tape cassette 12 is defined as the lower side of the tape cassette 12. In the following description of the structure, "lower" refers to the lower side of the tape cassette 12.

[0050] As an example, such as Figure 2 As shown, the magnetic tape cassette 12 is generally rectangular in shape when viewed from above and has a box-shaped housing 16. The magnetic tape MT is housed within the housing 16. The housing 16 is made of resin such as polycarbonate and has an upper housing 18 and a lower housing 20. The upper housing 18 and the lower housing 20 are joined together by welding (e.g., ultrasonic welding) and screw fixing, with the lower peripheral surface of the upper housing 18 in contact with the upper peripheral surface of the lower housing 20. The joining method is not limited to welding and screw fixing; other joining methods may also be used.

[0051] A feed reel 22 is rotatably housed inside the housing 16. The feed reel 22 includes a hub 22A, an upper flange 22B1, and a lower flange 22B2. The hub 22A is cylindrical. The hub 22A is the central portion of the feed reel 22, with its axis aligned vertically with the housing 16 and positioned at the center of the housing 16. The upper flange 22B1 and the lower flange 22B2 are each annular. The upper flange 22B1 is fixed to the upper end of the hub 22A in plan view at its central portion, and the lower flange 22B2 is fixed to the lower end of the hub 22A in plan view at its central portion. Alternatively, the hub 22A and the upper flange 22B1 can be integrally formed. Furthermore, the hub 22A and the lower flange 22B2 can also be integrally formed.

[0052] A magnetic tape MT is wound around the outer peripheral surface of the reel hub 22A, and the end of the magnetic tape MT in the width direction is held by an upper flange 22B1 and a lower flange 22B2.

[0053] An opening 16B is formed on the front side of the right wall 16A of the housing 16. The magnetic tape MT is pulled out through the opening 16B.

[0054] A cassette memory 24 is disposed within the lower housing 20. Specifically, the cassette memory 24 is housed at the right rear end of the lower housing 20. An IC chip with NVM is mounted within the cassette memory 24. In this embodiment, a so-called passive RFID tag is used as the cassette memory 24, and various information is read and written to the cassette memory 24 in a non-contact manner.

[0055] The cartridge memory 24 stores management information 15 for managing the tape cartridge 12. The management information 15 includes, for example, information related to the cartridge memory 24 (e.g., information that can identify the tape cartridge 12), information related to the tape MT (e.g., information indicating the recording capacity of the tape MT, information indicating a summary of the data recorded on the tape MT, information indicating the items of the data recorded on the tape MT, and information indicating the recording format of the data recorded on the tape MT), and information related to the tape drive 14 (e.g., information indicating the specifications of the tape drive 14 and the signals used in the tape drive 14).

[0056] As an example, such as Figure 3 As shown, the tape drive 14 includes a transport device 26, a magnetic head 28, a processing device 30, a storage device 32, a user interface (UI) system device 34, and a communication interface 35. A tape cassette 12 is loaded into the tape drive 14 in the direction of arrow A. The tape MT is pulled out of the tape cassette 12 and used in the tape drive 14.

[0057] The magnetic tape MT has a magnetic layer 29A, a base film 29B, and a back coating 29C. The magnetic layer 29A is formed on one side of the base film 29B, and the back coating 29C is formed on the other side of the base film 29B. Data is recorded on the magnetic layer 29A. The magnetic layer 29A contains a strongly magnetic powder. For example, a strongly magnetic powder commonly used in the magnetic layers of various magnetic recording media can be used as the strongly magnetic powder. A preferred example of a strongly magnetic powder is hexagonal ferrite powder. Examples of hexagonal ferrite powders include hexagonal strontium ferrite powder or hexagonal barium ferrite powder. The back coating 29C is, for example, a layer containing a non-magnetic powder such as carbon black. The base film 29B, also called a support, is formed, for example, from polyethylene terephthalate, polyethylene naphthalate, or polyamide. Additionally, a non-magnetic layer can be formed between the base film 29B and the magnetic layer 29A. In the magnetic tape MT, the surface on which the magnetic layer 29A is formed is the surface 31 of the magnetic tape MT, and the surface on which the back coating 29C is formed is the back surface 33 of the magnetic tape MT.

[0058] The tape drive 14 uses a magnetic head 28 to perform magnetic processing on the surface 31 of the magnetic tape MT. Here, magnetic processing refers to recording data on and reading data from the surface 31 of the magnetic tape MT (i.e., data playback). In this embodiment, the tape drive 14 selectively records and reads data from the surface 31 of the magnetic tape MT using the magnetic head 28. That is, the tape drive 14 removes the magnetic tape MT from the tape cartridge 12 and records data on or reads data from the surface 31 of the removed magnetic tape MT using the magnetic head 28. In this embodiment, the magnetic head 28 is an example of a "magnetic head" according to the present invention.

[0059] The processing device 30 controls the entire tape drive 14. In this embodiment, the processing device 30 is implemented by an ASIC, but the invention is not limited thereto. For example, the processing device 30 may also be implemented by an FPGA and / or a PLC. Furthermore, the processing device 30 may also be implemented by a computer including a CPU, flash memory (e.g., EEPROM and / or SSD, etc.), and RAM. It may also be implemented by a combination of two or more of ASIC, FPGA, PLC, and computer. That is, the processing device 30 may be implemented by a combination of hardware and software architectures. In this embodiment, the processing device 30 is an example of a "processor" according to the present invention.

[0060] Storage device 32 is connected to processing device 30, which writes various information to and reads various information from storage device 32. Examples of storage device 32 include flash memory and / or HDD. Flash memory and HDD are just examples; any memory can be used as long as it is a non-volatile memory that can be mounted on tape drive 14.

[0061] UI system device 34 is a device having a receiving function for receiving instruction signals indicating instructions from a user and a prompting function for providing prompting information to the user. The receiving function is implemented, for example, by a touch panel, hard keys (e.g., a keyboard), and / or a mouse. The prompting function is implemented, for example, by a display, a printer, and / or a speaker. UI system device 34 is connected to processing device 30. Processing device 30 acquires the instruction signals received by UI system device 34. Under the control of processing device 30, UI system device 34 prompts various information to the user.

[0062] Communication interface 35 is connected to processing device 30. Furthermore, communication interface 35 is connected to external device 37 via a communication network such as WAN and / or LAN (not shown). Communication interface 35 is responsible for transmitting and receiving various information between processing device 30 and external device 37 (e.g., data for recording on magnetic tape MT, data read from magnetic tape MT, and / or indication signals given to processing device 30). External device 37 can be, for example, a personal computer or a mainframe computer.

[0063] The conveying device 26 is a device that selectively conveys magnetic tape MT in both forward and reverse directions along a predetermined path, and includes a tape feeding motor 36, a tape reel 38, a tape winding motor 40, and multiple guide rollers GR. Here, "forward" refers to the feeding direction of the magnetic tape MT, and "reverse" refers to the rewinding direction of the magnetic tape MT.

[0064] Under the control of the processing device 30, the tape supply motor 36 rotates the tape reel 22 inside the tape cassette 12. The processing device 30 controls the rotation direction, speed, and torque of the tape reel 22 by controlling the tape supply motor 36.

[0065] The tape reel 38 rotates under the control of the processing device 30, driven by the tape motor 40. The processing device 30 controls the rotation direction, speed, and torque of the tape reel 38 by controlling the tape motor 40.

[0066] When the magnetic tape MT is wound onto the reel 38, the processing device 30 rotates the feed motor 36 and the winding motor 40 to feed the magnetic tape MT forward along a predetermined path. The speed and torque of the feed motor 36 and the winding motor 40 are adjusted according to the speed at which the magnetic tape MT is wound onto the reel 38. Furthermore, by adjusting the speed and torque of the feed motor 36 and the winding motor 40 respectively using the processing device 30, tension is applied to the magnetic tape MT.

[0067] Furthermore, the tension applied to the magnetic tape MT is controlled by adjusting the speed and torque of the feed motor 36 and the winding motor 40 using the processing device 30.

[0068] In addition, when the magnetic tape MT is rewound to the feed reel 22, the processing device 30 causes the feed motor 36 and the winding motor 40 to rotate so that the magnetic tape MT travels in the opposite direction along a predetermined path.

[0069] In this embodiment, the tension applied to the magnetic tape MT is controlled by controlling the rotational speed and torque of the feed motor 36 and the winding motor 40, but the present invention is not limited thereto. For example, the tension applied to the magnetic tape MT can also be controlled by using a tension adjustment roller, or by pulling the magnetic tape MT into a vacuum chamber.

[0070] Multiple guide rollers GR are rollers that guide the magnetic tape MT. The predetermined path, i.e. the tape MT's travel path, is determined by separately arranging multiple guide rollers GR at the position across the magnetic head 28 between the tape cartridge 12 and the reel 38.

[0071] The magnetic head 28 includes a magnetic element unit 42 and a support 44. The magnetic element unit 42 is held by the support 44 to contact the magnetic tape MT in the tape transport. The magnetic element unit 42 has multiple magnetic elements.

[0072] The magnetic element unit 42 records data on the magnetic tape MT conveyed by the transport device 26, or reads data from the magnetic tape MT conveyed by the transport device 26. Here, data refers, for example, to the servo pattern 52 (reference). Figure 6 Data other than servo pattern 52 is recorded in the data band DB (see reference). Figure 6 (Data).

[0073] The tape drive 14 includes a contactless read / write device 46. The contactless read / write device 46 is configured to face the back 24A of the cartridge memory 24 from the underside of the tape cassette 12 when it is filled with tape, and to read and write information to the cartridge memory 24 in a contactless manner.

[0074] As an example, such as Figure 4 As shown, the non-contact read / write device 46 releases a magnetic field MF from the underside of the tape cassette 12 toward the cartridge memory 24. The magnetic field MF penetrates the cartridge memory 24.

[0075] The contactless reader / writer 46 is connected to the processing unit 30. The processing unit 30 outputs a control signal to the contactless reader / writer 46. The control signal is a signal that controls the cassette memory 24. The contactless reader / writer 46 generates a magnetic field MF according to the control signal input from the processing unit 30, and releases the generated magnetic field MF toward the cassette memory 24.

[0076] The contactless read / write device 46 communicates with the cartridge memory 24 via a magnetic field MF, thereby performing processing on the cartridge memory 24 in accordance with control signals. For example, under the control of the processing device 30, the contactless read / write device 46 selectively performs processing to read information from the cartridge memory 24 and processing to store information in the cartridge memory 24 (i.e., processing to write information to the cartridge memory 24).

[0077] As an example, such as Figure 5 As shown, the magnetic tape drive 14 includes a moving mechanism 48. The moving mechanism 48 has a moving actuator 48A. For example, a voice coil motor can be considered as the moving actuator 48A. The moving actuator 48A is connected to a processing unit 30, and the processing unit 30 controls the moving actuator 48A. The moving actuator 48A generates power under the control of the processing unit 30. The moving mechanism 48 receives the power generated by the moving actuator 48A, thereby moving the magnetic head 28 along the width direction of the magnetic tape MT.

[0078] The magnetic tape drive 14 includes a tilting mechanism 49. The tilting mechanism 49 includes a tilt actuator 49A. For example, a voice coil motor can be considered as the tilt actuator 49A. The tilt actuator 49A is connected to a processing unit 30, which controls the tilt actuator 49A. Under the control of the processing unit 30, the tilt actuator 49A generates power. The tilting mechanism 49 receives the power generated by the tilt actuator 49A, thereby tilting the magnetic head 28 relative to the width direction WD of the magnetic tape MT towards the length direction LD of the magnetic tape MT (see reference). Figure 11 That is, the magnetic head 28 is tilted on the magnetic tape MT under the control of the processing device 30.

[0079] As an example, such as Figure 6 As shown, servo tapes SB1, SB2, and SB3 and data tapes DB1 and DB2 are formed on the surface 31 of the magnetic tape MT. In this embodiment, servo tapes SB1, SB2, and SB3 are an example of "three or more servo tapes" as described in this invention. Furthermore, for ease of explanation, servo tapes SB1 to SB3 will be referred to as "servo tapes SB" and data tapes DB1 and DB2 will be referred to as "data tapes DB" unless otherwise specified.

[0080] Servo tapes SB1 to SB3 and data tapes DB1 and DB2 are formed along the length direction LD (i.e., the entire length direction) of the magnetic tape MT. In other words, the length direction LD refers to the tape travel direction of the magnetic tape MT. The tape travel direction of the magnetic tape MT is defined as two directions: the direction in which the magnetic tape MT travels from the feed reel 22 side to the reel 38 side, i.e., the forward direction (hereinafter also simply referred to as "forward"), and the direction in which the magnetic tape MT travels from the reel 38 side to the feed reel 22 side, i.e., the reverse direction (hereinafter also simply referred to as "reverse"). In this embodiment, the length direction LD is an example of the "length direction" involved in this invention.

[0081] Servo tapes SB1 to SB3 are arranged at positions separated from each other along the width direction WD (hereinafter also simply referred to as "width direction WD") of the magnetic tape MT. For example, servo tapes SB1 to SB3 are arranged at equal intervals along the width direction WD. Furthermore, in this embodiment, "equal intervals" means, in addition to being completely equal, also including errors that are generally permissible in the technical field to which this invention pertains and do not depart from the spirit of this invention. Moreover, in this embodiment, the width direction WD is an example of the "width direction" involved in this invention.

[0082] Data band DB1 is positioned between servo bands SB1 and SB2, and data band DB2 is positioned between servo bands SB2 and SB3. That is, servo bands SB and data bands DB are arranged alternately along the width direction WD.

[0083] In addition, Figure 6 In the example shown, for ease of explanation (and to facilitate understanding of the invention), 3 servo bands SB and 2 data bands DB are shown, but this is just one example. The invention still applies even if there are 4 or more servo bands SB and 3 or more data bands DB.

[0084] Multiple servo patterns 52 are recorded along the length direction LD on the servo tape SB. The servo patterns 52 are divided into servo pattern 52A and servo pattern 52B. The multiple servo patterns 52 are arranged at constant intervals along the length direction LD. In addition, in this embodiment, "constant" means, in addition to being completely constant, also includes errors that are generally permissible in the technical field to which this invention pertains without departing from the spirit of this invention.

[0085] The servo band SB is divided into multiple frames 50 along its length LD. Frames 50 are defined by a set of servo patterns 52. Figure 6 In the example shown, servo patterns 52A and 52B are shown as one example of a set of servo patterns 52. Servo patterns 52A and 52B are adjacent along the length direction LD. Within frame 50, servo pattern 52A is located on the upstream side in the positive direction, and servo pattern 52B is located on the downstream side in the positive direction.

[0086] The servo pattern 52 is composed of linear magnetized region pairs 54. The linear magnetized region pairs 54 are divided into linear magnetized region pairs 54A and linear magnetized region pairs 54B.

[0087] Servo pattern 52A is composed of linear magnetized regions paired with 54A. In Figure 6 In the example shown, as an example of a linear magnetization region pair 54A, a pair of regions consisting of linear magnetization regions 54A1 and 54A2 are shown. Linear magnetization regions 54A1 and 54A2 are regions that are linearly magnetized.

[0088] The linear magnetization regions 54A1 and 54A2 are tilted in the opposite direction to the virtual straight line C1 along the width direction WD. Figure 6 In the example shown, the linear magnetized regions 54A1 and 54A2 are symmetrically tilted relative to the virtual straight line C1. More specifically, the linear magnetized regions 54A1 and 54A2 are not parallel to each other and are formed in a state where they are tilted only by an angle θ (e.g., 18 degrees) in the opposite direction of the length direction LD, with the virtual straight line C1 as the axis of symmetry. This angle θ is also called the azimuth angle. Furthermore, for ease of explanation, an example of how the linear magnetized regions 54A1 and 54A2 are symmetrical relative to the virtual straight line C1 is given here, but this is only one example. For example, the linear magnetized region 54A1 may be tilted relative to the virtual straight line C1 at an angle θ1, and the linear magnetized region 54A2 may be tilted relative to the virtual straight line C1 at an angle θ2 (≠θ1). In this case, the azimuth angle is defined by “(θ1+θ2) / 2”.

[0089] Linear magnetization region 54A1 is a collection of multiple straight lines (here, five straight lines as an example) magnetized with width W1, namely magnetized lines 54A1a. Linear magnetization region 54A2 is a collection of multiple straight lines (here, five straight lines as an example) magnetized with width W1, namely magnetized lines 54A2a. Magnetized lines 54A1a and 54A2a are not parallel to each other. Furthermore, magnetized lines 54A1a and 54A2a are formed in a state where they are tilted at an angle θ in opposite directions to the LD side of the axial length direction of the virtual line C1. In addition, for ease of explanation, an example of magnetized lines 54A1a and 54A2a being linearly symmetrical with respect to the virtual line C1 is given here, but this is only one example. For example, magnetized line 54A1a may be tilted at an angle θ1 with respect to the virtual line C1, and magnetized line 54A2a may be tilted at an angle θ2 (≠θ1) with respect to the virtual line C1.

[0090] Servo pattern 52B is composed of linear magnetized regions paired with 54B. In Figure 6In the example shown, as an example of a linear magnetization region pair 54B, a pair of regions consisting of linear magnetization regions 54B1 and 54B2 is shown. Linear magnetization regions 54B1 and 54B2 are regions that are linearly magnetized.

[0091] The linear magnetization regions 54B1 and 54B2 are tilted in the opposite direction to the virtual straight line C2 along the width direction WD. Figure 6 In the example shown, the linear magnetized regions 54B1 and 54B2 are symmetrically tilted relative to the virtual straight line C2. More specifically, the linear magnetized regions 54B1 and 54B2 are not parallel to each other, and are formed in a state where they are tilted only by an angle θ (e.g., 18 degrees) in the opposite direction of the axial length direction LD with respect to the virtual straight line C2. Furthermore, for ease of explanation, an example of how the linear magnetized regions 54B1 and 54B2 are symmetrical with respect to the virtual straight line C2 is given here, but this is only one example. For example, the linear magnetized region 54B1 may be tilted relative to the virtual straight line C2 at an angle θ1, and the linear magnetized region 54B2 may be tilted relative to the virtual straight line C1 at an angle θ2 (≠θ1).

[0092] Linear magnetization region 54B1 is a collection of multiple straight lines (four lines in this example) magnetized with a width W1, namely magnetized lines 54B1a. Linear magnetization region 54B2 is a collection of multiple straight lines (four lines in this example) magnetized with a width W1, namely magnetized lines 54B2a. Magnetized lines 54B1a and 54B2a are not parallel to each other. Furthermore, magnetized lines 54B1a and 54B2a are tilted at an angle θ in opposite directions along the axial length direction LD of the virtual line C2. For ease of explanation, an example of magnetized lines 54B1a and 54B2a being linearly symmetrical with respect to the virtual line C2 is given here, but this is only one example. For example, magnetized line 54B1a may be tilted at an angle θ1 with respect to the virtual line C2, and magnetized line 54B2a may be tilted at an angle θ2 (≠θ1) with respect to the virtual line C2.

[0093] A magnetic head 28 is disposed on the surface 31 side of the magnetic tape MT constructed as described above. A support 44 is formed in a cuboid shape and is arranged to span the surface 31 of the magnetic tape MT along its width direction WD. A plurality of magnetic elements of the magnetic element unit 42 are arranged in a straight line along the length direction of the support 44. Figure 6 In the example shown, the length direction of the magnetic head 28, i.e. the length direction of the bracket 44, is consistent with the width direction WD.

[0094] The magnetic element unit 42 comprises three servo read elements (SRs) and multiple data recording and playback elements (DRWs) as multiple magnetic elements. Here, for ease of understanding, three servo read elements (SRs) are illustrated, but this is only one example; the invention still applies even with four or more servo read elements (SRs). Furthermore, in this embodiment, "three servo read elements (SRs)" is an example of "three or more read elements" as understood in this invention.

[0095] The length of the support 44 in the longitudinal direction is sufficiently long relative to the width of the magnetic tape MT. For example, the length of the support 44 in the longitudinal direction is set such that it exceeds the width of the magnetic tape MT even if the magnetic element unit 42 is arranged in any position on the magnetic tape MT.

[0096] Three servo read elements SR are mounted on the read head 28. The relative positional relationship between the support 44 and the three servo read elements SR on the read head 28 is fixed. The three servo read elements SR are composed of servo read elements SR1, SR2 and SR3. The servo read elements SR1, SR2 and SR3 are arranged at intervals along the length direction of the support 44 (for example, arranged at equal intervals along the length direction of the support 44).

[0097] Servo read element SR1 is disposed at one end of magnetic element unit 42. Servo read element SR3 is disposed at the other end of magnetic element unit 42. Servo read element SR2 is disposed between servo read elements SR1 and SR3 along the length of the magnetic head 28 (here, as an example, the center). Figure 6 In the example shown, the servo readout element SR1 is positioned corresponding to the servo band SB3. Furthermore, in Figure 6 In the example shown, the servo readout element SR2 is positioned corresponding to the servo band SB2. Furthermore, in Figure 6 In the example shown, the servo readout element SR3 is positioned corresponding to the servo band SB1.

[0098] Multiple data recording and playback elements (DRWs) are arranged in a straight line between servo read elements SR1 and SR2, and between servo read elements SR2 and SR3, respectively. These DRWs are also spaced apart along the length of the magnetic head 28 (e.g., equally spaced along the length of the magnetic head 28). Figure 6 In the example shown, multiple data recording playback elements (DRWs) are respectively positioned at the positions corresponding to data tape DB2 and data tape DB1.

[0099] The width W2 of the servo reading element SR (i.e., the length in the longitudinal direction of the bracket 44) is preferably set to satisfy the following formula (1), and more preferably to satisfy the following formula (2). In formulas (1) and (2), "θ" represents the aforementioned angle θ, and "W1" represents the aforementioned width W1.

[0100] W2≤(1 / tanθ)×W1……(1) W2≤(0.5 / tanθ)×W1……(2) The processing unit 30 acquires the result of the servo pattern 52 read by the servo read element SR, namely the servo pattern signal. The processing unit 30 performs servo control according to the acquired servo pattern signal. Here, servo control refers to the control that moves the magnetic head 28 along the width direction WD of the magnetic tape MT by actuating the moving mechanism 48 according to the servo pattern 52 read by the servo read element SR.

[0101] By performing servo control, multiple data recording and playback elements (DRWs) are positioned on a designated area within the data tape (DB), and in this state, magnetic processing is performed on the designated area within the data tape (DB). Figure 6 In the example shown, multiple data recording playback elements (DRWs) perform magnetic processing on a specified area within the data tape DB2.

[0102] As an example, such as Figure 7 As shown, in data band DB2, data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7 and DT8 are formed from the servo band SB2 side to the servo band SB3 side as multiple segmented regions obtained by dividing data band DB2 along the width direction WD.

[0103] Along the width direction WD, the magnetic head 28 has data recording and playback elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 as multiple data recording and playback elements DRW. Data recording and playback elements DRW1 to DRW8 correspond one-to-one with data tracks DT1 to DT8, and can perform data playback (i.e., reading) from data tracks DT1 to DT8 and data recording (i.e., writing) to data tracks DT1 to DT8.

[0104] Hereinafter, without special distinction, data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7, and DT8 will be referred to as "data tracks DT". Furthermore, hereafter, without special distinction, data recording and playback elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 will be referred to as "data recording and playback elements DRW".

[0105] Additionally, although the illustration is omitted, it is in data band DB1 (reference). Figure 6 On the ), multiple data tracks DT are also formed, which are equivalent to data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7 and DT8.

[0106] As an example, such as Figure 8 As shown, data track DT has a segmented data track group DTG. Data tracks DT1 to DT8 correspond to segmented data track groups DTG1 to DTG8. Hereinafter, unless otherwise specified, segmented data track groups DTG1 to DTG8 will be referred to as "segmented data track group DTG".

[0107] The segmented data track group DTG1 is a collection of multiple segmented data tracks obtained by dividing the data track DT along the width direction WD. Figure 8 In the example shown, as a case of a split data track group DTG1, the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11 and DT_12 are shown, obtained by dividing the data track DT into 12 equal parts along the width direction WD. The data recording and playback element DRW1 is responsible for the magnetic processing of the split data track group DTG1. That is, the data recording and playback element DRW1 is responsible for recording data from the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11 and DT_12, and for playing back data from the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11 and DT_12. Hereinafter, without distinguishing between the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11 and DT_12, they will be referred to as "split data track DT_N".

[0108] Data recording and playback elements DRW2 to DRW8, like data recording and playback element DRW1, are responsible for magnetic processing of the segmented data track group DTG corresponding to the data track DT of each data recording and playback element DRW.

[0109] The data recording and playback element DRW is moved by the moving mechanism 48 (reference). Figure 6 The read / write head 28 is moved in the width direction WD (i.e., along the length direction of the read / write head 28) to a position corresponding to a specified data track DT among multiple data tracks DT. This is achieved by using servo pattern 52 (reference). Figure 6 and Figure 7 Servo control is performed, and the data recording and playback element DRW stops at the position corresponding to the specified data track DT.

[0110] As an example, such as Figure 9 As shown, paths P1 to P12 are evenly spaced along the width direction WD in servo pattern 52. Paths P1 to P12 are connected to multiple segmented data tracks DT_N contained in the segmented data track group DTG (in... Figure 8 and Figure 9 The example shown corresponds to 12 split data tracks (DT_N). Paths P1 to P12 are roughly divided into paths Pa1 to Pa12 used when recording data and paths Pb1 to Pb12 used when playing back data. Hereinafter, when there is no need to distinguish between paths P1 to P12, they will be referred to as "path P".

[0111] When the data recording and playback element DRW performs magnetic processing on the segmented data track DT_N designated as the target of magnetic processing, the moving mechanism 48 moves the read / write head 28 along the width direction WD so that the servo read / write element SR passes through the path P corresponding to the target segmented data track. For example, when the data recording and playback element DRW performs magnetic processing on the segmented data track DT_1, the moving mechanism 48 moves the read / write head 28 along the width direction WD so that the servo read / write element SR passes through path P1. Similarly, for example, when the data recording and playback element DRW performs magnetic processing on the segmented data track DT_12, the moving mechanism 48 moves the read / write head 28 along the width direction WD so that the servo read / write element SR passes through path P12. Thus, the data recording and playback element DRW1 faces the target segmented data track, enabling magnetic processing of the target segmented data track.

[0112] In recent years, research has been advancing on technologies related to reducing the impact of TDS. It is known that TDS is affected by factors such as temperature, humidity, pressure of the magnetic tape wound on the disc, and degradation over time. Without any measures, TDS increases, causing track deviations (i.e., the positional shift of the data recording playback element DRW relative to the tracks within the data tape DB) in scenarios where magnetic processing of the data tape DB is performed.

[0113] exist Figure 10The example shown illustrates how the width of the magnetic tape MT shrinks over time. Furthermore, in this embodiment, the distance between servo tapes SB1 and SB2 in the width direction WD (e.g., the distance between the center positions of servo tape SB1 and SB2 in the width direction WD) is labeled "d1", and the distance between servo tapes SB2 and SB3 in the width direction WD (e.g., the distance between the center positions of servo tape SB2 and SB3 in the width direction WD) is labeled "d2". Moreover, in this embodiment, the distance between servo tapes SB1 and SB2 in the width direction WD after the width of the magnetic tape MT changes over time is labeled "d1A", and the distance between servo tapes SB2 and SB3 in the width direction WD after the width of the magnetic tape MT changes over time is labeled "d2A". Furthermore, in this embodiment, the change in the distance between servo tape SB1 and servo tape SB2 in the width direction WD as the width of the magnetic tape MT shrinks over time is denoted as "Δd1", and the change in the distance between servo tape SB2 and servo tape SB3 in the width direction WD as the width of the magnetic tape MT shrinks over time is denoted as "Δd2".

[0114] like Figure 10 As shown, even when the width of the magnetic tape MT shrinks over time, with the same change Δd1 and Δd2, and distance d1 becomes distance d1A (=d1+Δd1) and distance d2 becomes distance d2A (=d2+Δd2), track deviation will still occur. Track deviation will also occur when the width of the magnetic tape MT sometimes widens. That is, if the width of the magnetic tape MT narrows or widens over time, the position of the servo read element SR relative to the servo pattern 52 will deviate from its designed position (e.g., the center positions of the linear magnetized regions 54A1, 54A2, 54B1, and 54B2) in the width direction WD. If the position of the servo read element SR relative to the servo pattern 52 deviates from its designed position in the width direction WD, the accuracy of servo control decreases, causing the track position within the data tape DB to shift from the position of the data recording and playback element DRW. As a result, magnetic processing of the originally planned track cannot be performed.

[0115] As a method to reduce the impact of TDS (i.e., to maintain the reading position of the servo read element SR relative to the servo pattern 52 at a predetermined position determined in the design), for example, Figure 11As shown, it is known that there is a method to tilt the magnetic head 28 on the magnetic tape MT when the change amount Δd1 and the change amount Δd2 are the same (that is, the shrinkage amount of servo tape SB1 and servo tape SB2 in the width direction WD is the same as the shrinkage amount of servo tape SB2 and servo tape SB3 in the width direction WD).

[0116] The magnetic head 28 has a rotation axis RA. The rotation axis RA is positioned at the top center of the magnetic element unit 42 included in the magnetic head 28. The magnetic head 28 is rotatably held in a tilting mechanism 49 via the rotation axis RA. A virtual center line, or virtual straight line C3, is provided in the magnetic head 28. The virtual straight line C3 is a straight line extending along the top length direction of the magnetic head 28 (i.e., the direction in which multiple data recording and playback elements DRW are arranged) through the rotation axis RA. The magnetic head 28 is held by the tilting mechanism 49 in an orientation in which the virtual straight line C3 is tilted relative to a virtual straight line C4 along the width direction WD towards the length direction LD of the magnetic tape MT. Figure 11 In the example shown, the magnetic head 28 is positioned such that the virtual straight line C3 is tilted relative to the virtual straight line C4 toward the feed reel 22 (i.e., from...). Figure 11 The tilting posture (when viewed from the paper surface side) is maintained by the tilting mechanism 49 in a counterclockwise direction.

[0117] The tilting mechanism 49 receives a tilting actuator 49A (reference). Figure 5 The power of the magnetic head 28 causes it to rotate about the rotation axis RA on the surface 31 of the magnetic tape MT. Under the control of the processing device 30, the tilting mechanism 49 causes the magnetic head 28 to rotate about the rotation axis RA on the surface 31 of the magnetic tape MT, thereby changing the direction and angle of the tilt (i.e., azimuth angle) of the virtual line C3 relative to the virtual line C4.

[0118] The direction and angle of inclination of virtual line C3 relative to virtual line C4 change according to temperature, humidity, pressure of magnetic tape MT wound on the disk and time deterioration, or the stretching and contraction of magnetic tape MT in the width direction WD caused by these factors. As a result, the position of servo read element SR relative to servo pattern 52 is maintained at the predetermined position set in the design.

[0119] Here, for reference Figure 12A and Figure 12B This paper will explain an example of a magnetic tape (MT) method in which data is recorded using the SMR method. Figure 12A This is a conceptual diagram illustrating an example of a method in which multiple segmented data tracks DT_N are staggered and overlapped along the other end of the width of the magnetic tape MT to form a data track DT, which is achieved by recording data on the surface 31 of the magnetic tape MT in an SMR manner on the data tape DB2 between the servo tape SB2 and the servo tape SB3. Figure 12BThis is a conceptual diagram illustrating an example of a method in which multiple segmented data tracks DT_N are staggered and overlapped along the other side of the width of the magnetic tape MT to form a data track DT, which is formed by recording data on the surface 31 of the magnetic tape MT in an SMR manner on the data tape DB1 between the servo tape SB1 and the servo tape SB2.

[0120] As an example, such as Figure 12A and Figure 12B As shown, all the split data tracks DT_N that form one data track DT (here, as an example, 12 split data tracks DT_N) are formed by recording data onto the magnetic tape MT in SMR mode by the data recording and playback element DRW. SMR mode is a magnetic recording method used to achieve high-density data recording on the magnetic tape MT, also known as shingled recording mode.

[0121] exist Figure 12A and Figure 12B In the example shown, the width direction WD is defined by the direction at one end of the width of the magnetic tape MT, i.e., the first direction WD1, and the direction at the other end of the width of the magnetic tape MT, i.e., the second direction WD2. The second direction WD2 is the direction in which data is staggered on the magnetic tape MT by recording data in SMR mode. Multiple segmented data tracks DT_N of each data track DT are recorded on the magnetic tape MT in a staggered and overlapping manner along the second direction WD2. For each data track DT, adjacent segmented data tracks DT_N in the width direction WD are staggered by a constant spacing Tp along the width direction WD.

[0122] In this embodiment, the multiple segmented data tracks DT_N of each data track DT is an example of the "multiple data tracks" involved in this invention. Furthermore, in Figure 12A and Figure 12B In the example shown, to make it easier to understand the configuration relationship of the split data tracks DT_1 to DT_12, the split data tracks DT_1 to DT_12 are deliberately staggered along the length direction LD. However, in reality, the split data tracks DT_1 to DT_12 are not staggered along the length direction LD, but rather the split data tracks DT_1 to DT_12 extend along the length direction LD.

[0123] Guard bands (GB) are formed between data tracks (DT) in the width direction (WD). The guard bands (GB) are blank areas not used for data recording and playback. The guard bands (GB) formed between data tracks (DT) serve, for example, to prevent the effects of magnetic processing on one data track (DT) from affecting the other data track (DT) due to variations in the spacing between data recording / playback elements (DRW) (e.g., variations within manufacturing tolerances).

[0124] Furthermore, a guard band GB is formed between the servo band SB and the data band DB in the width direction WD. For example, the guard band GB between the servo band SB and the data band DB is responsible for the following function: preventing the magnetic influence caused by the servo read element SR on the servo band SB from affecting the data track DT, or the magnetic influence caused by the data recording and playback element DRW from affecting the servo band SB.

[0125] As an example, such as Figure 13 As shown, the magnetic head 28 includes a first recording module DWM1, a second recording module DWM2, and a playback module DRM. Hereinafter, for ease of explanation, the first recording module DWM1 and the second recording module DWM2 will be referred to as "recording module DWM" without distinction.

[0126] The recording module DWM and the playback module DRM are along the length direction LD (in other words, in... Figure 13 The example shown is configured along the short side of the magnetic head 28. For example, along the length direction LD, one recording module DWM is configured on each side of the playback module DRM. Figure 13 The example shown schematically illustrates the relationship between and Figure 3 Observe in the opposite direction to the direction indicated by arrow B1. Figure 3 The example shown is of the surface side of the magnetic head 28, with the feed reels 22 on both sides of the playback module DRM along the length direction LD (see reference). Figure 3 The first recording module DWM1 is configured on the side, and the tape reels 38 are located on both sides of the playback module DRM in the length direction LD (see reference). Figure 3 The second recording module DWM2 is configured on the side.

[0127] A magnetic element unit 42 is provided on the recording module DWM and the playback module DRM. The magnetic element unit 42 includes a servo read element SR1, a servo read element SR2, a servo read element SR3, a first data recording element group DWG1, a second data recording element group DWG2, and a data playback element group DRG. The first data recording element group DWG1 is located on the first recording module DWM1. The second data recording element group DWG2 is located on the second recording module DWM2. The data playback element group DRG is located on the playback module DRM.

[0128] Servo read element SR1 is located at one end of magnetic element unit 42, and servo read element SR3 is located at the other end of magnetic element unit 42. Furthermore, servo read element SR2 is located at the center of servo read element SR1 and servo read element SR3 among all the magnetic elements constituting magnetic element unit 42.

[0129] A data recording and playback element DRW is provided between servo reading element SR1 and servo reading element SR2, and between servo reading element SR2 and servo reading element SR3, respectively. The servo recording and playback element DRW has a first data recording element DW1, a second data recording element DW2, and a data playback element DR.

[0130] The first data recording element group (DWG1) includes multiple first data recording elements (DW1), which are arranged in a straight line along a virtual line C3. The second data recording element group (DWG2) includes multiple second data recording elements (DW2), which are arranged in a straight line along a virtual line C3. The data playback element group (DRG) includes multiple data playback elements (DR), which are arranged in a straight line along a virtual line C3.

[0131] For ease of explanation, without distinguishing between the first data recording element DW1 and the second data recording element DW2, the first data recording element DW1 and the second data recording element DW2 will be referred to as "data recording element DW".

[0132] The data recording element (DW) records data onto the data track (DT). The data playback element (DR) plays back the data from the data track (DT).

[0133] The first data recording element group DWG1, the second data recording element group DWG2, and the data playback element group DRG are arranged along the length direction LD, from the feed reel 22 side to the reel 38 side, with a constant interval between them in the order of the first data recording element group DWG1, the data playback element group DRG, and the second data recording element group DWG2. Here, the constant interval refers, for example, to an interval that is predetermined through experiments and / or computer simulations, so as to prevent crosstalk between the data recording element DW and the data playback element DR.

[0134] The servo read element SR has a first servo read element SRa, a second servo read element SRb, and a third servo read element SRc. That is, servo read elements SR1, SR2, and SR3 each have a first servo read element SRa, a second servo read element SRb, and a third servo read element SRc.

[0135] The first servo read element SRa, the second servo read element SRb, and the third servo read element SRc feed reel 22 from the length direction LD (reference). Figure 3 Side to reel 38 (reference) Figure 3 On the side, the first servo read element SRa, the second servo read element SRb, and the third servo read element SRc are arranged in that order.

[0136] The first data recording element group DWG1 has multiple first data recording elements DW1. The first data recording elements DW1 record data for the corresponding data track DT in all data tracks DT contained in the data tape DB.

[0137] Three first servo read elements SRa are provided on the first recording module DWM1. The three first servo read elements SRa are adjacent to each other in the width direction WD, separated by multiple first data recording elements DW1. On the first recording module DWM1, the multiple first data recording elements DW1 are arranged in a straight line and are equally spaced between adjacent first servo read elements SRa.

[0138] The number of first data recording elements (DW1) contained in the first data recording element group (DWG1) is the same as the number of data tracks (DT) contained in the data tape (DB). Figure 11 In the example shown, eight first data recording elements DW1 are illustrated as multiple first data recording elements DW1, and the positions of these first data recording elements DW1 are relative to data recording and playback elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see reference). Figure 7 and Figure 8 The position corresponds to ).

[0139] The Data Playback Element Group (DRG) has multiple Data Playback Elements (DR). Each DR plays back data from the corresponding data track DT contained in the data tape DB.

[0140] The playback module DRM has three second servo read elements SRb, which are adjacent to each other in the width direction WD, separated by multiple data playback elements DR. In the playback module DRM, the multiple data playback elements DR are arranged in a straight line and at equal intervals between adjacent second servo read elements SRb.

[0141] The number of data playback elements (DRs) contained in the data playback element group (DRG) is the same as the number of data tracks (DTs) contained in the data tape (DB). Figure 13 In the example shown, eight data playback elements (DRs) are illustrated as multiple data playback elements (DRs), and the positions of these data playback elements (DRs) are relative to data recording playback elements (DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8) (see reference). Figure 7 and Figure 8 The position corresponds to ).

[0142] The second data recording element group DWG2 has multiple second data recording elements DW2. The second data recording elements DW2 record data for the corresponding data track DT in all data tracks DT contained in the data tape DB.

[0143] Three third servo read elements SRc are provided on the second recording module DWM2. The three third servo read elements SRc are adjacent to each other in the width direction WD, separated by multiple second data recording elements DW2. On the second recording module DW2, the multiple second data recording elements DW2 are arranged in a straight line and are equally spaced between adjacent third servo read elements SRc.

[0144] The number of secondary data recording elements (DW2) contained in the secondary data recording element group (DWG2) is the same as the number of data tracks (DT) contained in the data tape (DB). Figure 13 In the example shown, eight second data recording elements DW2 are illustrated as multiple second data recording elements DW2, and the positions of these second data recording elements DW2 are relative to the data recording and playback elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see reference). Figure 7 and Figure 8 The position corresponds to ).

[0145] Here, an example of the geometric relationship between the data recording element DW and the data playback element DR contained in the data recording and playback element DRW corresponding to one data track DT will be explained.

[0146] In the magnetic head 28 on the magnetic tape MT, the center position of the data recording element DW included in the data recording and playback element DRW corresponding to one data track DT coincides with the center position of the data playback element DR in the width direction WD. Here, the center position of the data recording element DW refers, for example, to the center position of the data recording element DW in the width direction WD. Similarly, the center position of the data playback element DR refers, for example, to the center position of the data playback element DR in the width direction WD. Furthermore, "coincidence" means, in addition to complete coincidence, also includes a degree of error that is generally permissible in the technical field to which this invention pertains and does not depart from the spirit of this invention.

[0147] Furthermore, in this embodiment, the center position of the data recording element DW and the center position of the data playback element DR are aligned in the width direction WD, which is also to achieve the so-called "Read while write". In "Read while write", in order to verify whether the data recorded during the recording operation on the magnetic tape MT is recorded correctly, if the first recording module DWM1 records data on the magnetic tape MT according to the servo pattern signal obtained by the first servo read element SRa while the magnetic tape MT is being transported in the forward direction, then the playback module DRM immediately plays back the data. When the magnetic tape MT is being transported in the reverse direction and the second recording module DWM2 is recording data on the magnetic tape MT, "Read while write" is performed between the second recording module DWM2 and the playback module DRM in the same manner.

[0148] Furthermore, in the data recording and playback element DRW corresponding to one data track DT, the length L1 of the data recording element DW in the width direction WD is longer than the length β1 of the data playback element DR in the width direction WD, and is more than twice the pitch Tp. Moreover, the length β1 is less than the pitch Tp (reference). Figure 12A and Figure 12B ).

[0149] Based on the servo pattern signal obtained by reading the servo pattern 52 from the first servo read element SRa, the first data recording element DW1 forms a data track DT in SMR mode (reference). Figure 12A and Figure 12B After that, the data playback element DR retrieves the segmented data track DT_N contained in the data track DT (reference). Figure 12A and Figure 12B Data playback is performed. At this time, according to the servo pattern signal obtained by reading servo pattern 52 by the second servo reading element SRb, the data playback element DR plays back the data from the segmented data track DT_N.

[0150] If the data track DT is formed using SMR (Single Recording Mode), adjacent split data tracks DT_N overlap. Therefore, when data is played back by the data playback element DR, the playback area becomes narrower compared to when data is recorded by the first data recording element DW1. For example, in Figure 12A and Figure 12B In the example shown, only the region with a spacing Tp within the segmented data track DT_N becomes the playback target region for data based on the data playback element DR.

[0151] The positions of the first servo read element SRa and the second servo read element SRb are aligned in the width direction WD. Therefore, when playing back data from the data track DT formed in the SMR manner (i.e., when the data playback element DR plays back data from the segmented data track DT_N), compared to when data is recorded by the first data recording element DW1, the position of the head 28 needs to be offset in the width direction WD by a distance Dr (={(length L1) - (pitch Tp)} / 2) only greater than the distance Tp. That is, the second servo read element SRb needs to read the servo pattern 52 on a path P that is offset by a distance Dr in the width direction WD from the path P through which the first servo read element SRa passes.

[0152] For example, in the case where the data playback element DR plays back data from a specific segmented data track DT_N formed by data recorded by the data recording element DW, the second servo read element SRb reads the servo pattern 52 on a path P that is offset by only a distance Dr from the path P through which the first servo read element SRa passes along the first direction WD1.

[0153] exist Figure 10 and Figure 11 The example shown describes the case where the changes Δd1 and Δd2 are the same, but the changes Δd1 and Δd2 are not always the same. For example, as... Figure 14 As shown, it is also possible that the changes Δd1 and Δd2 are different. Figure 14 In the example shown, the change Δd2 is less than the change Δd1. In this case, for example, even if the position of servo read element SR1 relative to the servo pattern 52 within servo tape SB3 and the position of servo read element SR2 relative to the servo pattern 52 within servo tape SB2 can be aligned with the predetermined positions by tilting the magnetic head 28 on the magnetic tape MT, the position of servo read element SR3 relative to the servo pattern 52 within servo tape SB1 cannot be aligned with the predetermined positions. Furthermore, if the position of servo read element SR3 relative to the servo pattern 52 within servo tape SB1 and the position of servo read element SR2 relative to the servo pattern 52 within servo tape SB2 can be aligned with the predetermined positions by tilting the magnetic head 28 on the magnetic tape MT, the position of servo read element SR1 relative to the servo pattern 52 within servo tape SB3 cannot be aligned with the predetermined positions. Therefore, as described above, it is difficult to align the data playback element DR with the tracks formed by recording data on the magnetic tape MT in an SMR manner.

[0154] Therefore, in this embodiment, the magnetic tape system 10 performs TDS (Total Displacement) reduction control to reduce the impact of TDS on the magnetic tape MT after a certain period of storage. Hereinafter, for ease of understanding of the present invention, reference will be made to... Figures 15-17 Use the saved function 62 (reference) Figure 15 ) and the adjusted linear function 66 (reference) Figure 17 The behavior of reducing the impact of TDS is explained, and then, refer to Figure 17 This section explains how TDS impact reduction control is actually implemented (i.e., an example of the specific control measures taken).

[0155] exist Figure 15 This illustrates an example of the correlation between the read position of the servo read element SR relative to the servo band SB and the distance to the servo band. Figure 15 The diagram shows the functions 60 before and 62 after storage. Function 60 before storage is the function obtained before storing the magnetic tape MT for a certain period of time, and function 62 after storage is the function obtained after storing the magnetic tape MT for a certain period of time.

[0156] Before storage, function 60, and after storage, function 62, respectively, represent the correlation between the reading position of the servo reading element SR relative to the servo tape SB and the distance to the servo tape. Figure 15 In the example shown, the horizontal axis represents the reading position of the servo readout element SR relative to the servo band SB, and the vertical axis represents the servo band distance. For ease of explanation, the reading position of the servo readout element SR relative to the servo band SB will be labeled "x", and the servo band distance will be labeled "d". Furthermore, in Figure 15 For ease of explanation, the TDS effect reduction control at a certain measurement point in the length direction LD is illustrated below. However, in practice, the same TDS effect reduction control is performed at multiple measurement points (e.g., all measurement points) in the length direction LD.

[0157] exist Figure 15 In the example shown, reading positions x1, x2, and x3 are illustrated at a measurement point along the length direction LD, serving as reading positions x. Reading position x1 is the reading position of the servo reading element SR3 relative to the servo tape SB1. As an example of reading position x1, the center position along the width direction WD of the servo tape SB1 can be considered. Reading position x2 is the reading position of the servo reading element SR2 relative to the servo tape SB2. As an example of reading position x2, the center position along the width direction WD of the servo tape SB2 can be considered. Reading position x3 is the reading position of the servo reading element SR1 relative to the servo tape SB3. As an example of reading position x3, the center position along the width direction WD of the servo tape SB3 can be considered. Reading positions x1, x2, and x3 are aligned along the length direction LD.

[0158] The servo tape distance d is the distance between servo tape SB1 and other servo tapes SB in the width direction WD. Servo tape SB1 is the reference servo tape SB among servo tapes SB1, SB2, and SB3 before and after the magnetic tape MT has been stored for a certain period. Figure 15 In the example shown, the distance between servo band SB1 and servo band SB2 (i.e., the servo band SB located between servo band SB1 and servo band SB3 among all servo bands SB) in the width direction WD, and the distance between servo band SB1 and servo band SB3 (i.e., the servo band SB furthest from servo band SB1 in the width direction WD among all servo bands SB) in the width direction WD are measured. The measurement results are expressed by the function 60 before storage and the function 62 after storage. The distance between servo band SB1 and servo band SB2 in the width direction WD refers to... Figure 10 The distance d1 shown refers to the distance between servo band SB1 and servo band SB3 in the width direction WD. Figure 10 The distance d1 shown is... Figure 10 The sum of distances d2 shown.

[0159] The servo band distance d is determined based on the servo pattern signals obtained by parallel reading of multiple servo patterns 52 of the corresponding servo bands SB by servo readout elements SR1, SR2, and SR3. For example, the servo band distance d for the two servo bands SB is calculated based on the tilt angle (i.e., the deflection angle) of the readout head 28 in a tilted state such that the center position of each of the two servo bands SB in the width direction WD is read by the servo readout element SR. The calculation of the servo band distance d can be performed, for example, using a formula where the deflection angle is the independent variable and the servo band distance d is the dependent variable.

[0160] Furthermore, this calculation method is only one example. For instance, with the read / write head 28 tilted so that the servo read element SR reads the center positions of the two servo bands SB in the width direction WD, the servo band distance d for the two servo bands SB can be calculated based on the time difference (hereinafter referred to as the "reading time difference") between the timing of reading a servo pattern 52 at a specific position in the length direction LD among the multiple servo patterns 52 in one servo band SB and the timing of reading a servo pattern 52 at a specific position in the length direction LD among the multiple servo patterns 52 in the other servo band SB. In this case, the calculation of the servo band distance d can, for example, use an expression that sets the reading time difference as the independent variable and the servo band distance d as the dependent variable.

[0161] Here, an example of the method for creating the pre-storage function 60 will be described. The pre-storage function 60 is a function representing the correlation between the servo tape distance d measured from the magnetic tape MT before data recording and the read position x. The magnetic tape MT before data recording (hereinafter, without the symbol, referred to as "data recording tape") refers to the magnetic tape MT stored for 5 days in an environment with an ambient temperature of 23°C and a relative humidity of 50% without data recording. In addition, the specific values ​​of ambient temperature, relative humidity, time, tension, speed, quantity, and length illustrated in this embodiment are only one example, and other values ​​may also be used.

[0162] In this embodiment, in order to obtain the pre-storage function 60, the pre-data recording magnetic tape is loaded into the magnetic tape drive 14, and the magnetic tape system 10 performs the following steps 1 to 4 in an environment with an ambient temperature of 23°C and a relative humidity of 50%.

[0163] In step 1, using the magnetic tape system 10, a tension of 0.70 N (Newtons) is applied to the magnetic tape along the length direction LD before data recording.

[0164] In step 2, while applying a tension of 0.70N to the magnetic tape along its length direction LD before data recording, the magnetic tape is moved back and forth a number of times equal to the number of data tapes DB.

[0165] In step 3, for data tapes DB (here, for example, data tapes DB1 or DB2) that have traveled back and forth on the magnetic tape a different number of times before data recording, the servo tape distance d (here, for example, distance d1 or d2) between adjacent servo tapes SB in the width direction WD is measured every 2.4 mm along the length direction LD throughout the entire length of the data recording area. That is, distance d1 is measured every 2.4 mm along the length direction LD throughout the entire length of the data recording area, and distance d2 is measured every 2.4 mm along the length direction LD throughout the entire length of the data recording area.

[0166] In step 4, at a certain measurement point along the length direction LD, the distance d1 measured in step 3 is used as the servo band distance d corresponding to the reading position x2 (i.e., the lengths of servo bands SB1 and SB2 along the width direction WD), and the distance d2 measured in step 3 is used as the servo band distance d corresponding to the reading position x3 (i.e., the lengths of servo bands SB1 and SB2 along the width direction WD) to create the pre-storage function 60. The pre-storage function 60 becomes a function of the servo band distance d proportional to the reading position x.

[0167] In addition, for ease of explanation, at a certain measurement point in the length direction LD, the distance d1 measured in step 3 will be called "the distance of the first storage of 0 months", and the distance d2 measured in step 3 will be called "the distance of the second storage of 0 months".

[0168] Next, an example of how the storage function 62 is created will be explained. The storage function 62 is a function representing the correlation (in other words, the correspondence) between the servo tape distance d measured from the tape after a certain storage period and the read position x. The tape after a certain storage period refers to a data-recorded tape that has been stored for a certain period (in this example, 10 years). The data-recorded tape refers to the tape MT obtained by recording data from the tape before data recording.

[0169] In this embodiment, to obtain the stored function 62, firstly, the data-recorded magnetic tape is stored for one month (30 days) at an ambient temperature of 32°C and a relative humidity of 55%. Then, the data-recorded magnetic tape stored for one month at an ambient temperature of 32°C and a relative humidity of 55% (hereinafter referred to as the "one-month stored tape") is stored for five days at an ambient temperature of 23°C and a relative humidity of 50%. The one-month stored tape, stored for five days at an ambient temperature of 23°C and a relative humidity of 50%, is loaded into the tape drive 14, and the above-described steps 1 to 3 are performed by the tape system 10 at an ambient temperature of 23°C and a relative humidity of 50%. By performing the third step, the distance d1 measured on the one-month stored tape (i.e., the first one-month stored distance) and the distance d2 measured on the one-month stored tape (i.e., the second one-month stored distance) are obtained.

[0170] Next, the magnetic tape stored for one month is further stored for one month at an ambient temperature of 32°C and a relative humidity of 55%. Then, the magnetic tape with data recordings stored for another month at an ambient temperature of 32°C and a relative humidity of 55% (hereinafter referred to as the "magnetic tape stored for two months") is stored for five days at an ambient temperature of 23°C and a relative humidity of 50%. The magnetic tape stored for two months at an ambient temperature of 23°C and a relative humidity of 50% is loaded into the magnetic tape drive 14, and the magnetic tape system 10 performs the processing described in steps 1 to 3 above at an ambient temperature of 23°C and a relative humidity of 50%. By performing the processing in step 3, the distance d1 measured on the magnetic tape stored for two months (i.e., the first distance stored for two months) and the distance d2 measured on the magnetic tape stored for two months (i.e., the second distance stored for two months) are obtained.

[0171] Next, the magnetic tape stored for 2 months is further stored for 1 month at an ambient temperature of 32°C and a relative humidity of 55%. Then, the magnetic tape with data recordings stored for another month at an ambient temperature of 32°C and a relative humidity of 55% (hereinafter referred to as the "magnetic tape stored for 3 months") is stored for 5 days at an ambient temperature of 23°C and a relative humidity of 50%. The magnetic tape stored for 3 months at an ambient temperature of 23°C and a relative humidity of 50% is loaded into the magnetic tape drive 14, and the magnetic tape system 10 performs the above-described steps 1 to 3 at an ambient temperature of 23°C and a relative humidity of 50%. By performing the processing in step 3, the distance d1 measured on the magnetic tape stored for 3 months (i.e., the first distance stored for 3 months) and the distance d2 measured on the magnetic tape stored for 3 months (i.e., the second distance stored for 3 months) are obtained.

[0172] Here, with the storage time required for obtaining the data record set to 0 hours, the storage time required for obtaining the tape for 1 month set to 720 hours (=24 hours × 30 days), the storage time required for obtaining the tape for 2 months set to 1440 hours (=24 hours × 60 days), and the storage time required for obtaining the tape for 3 months set to 2160 hours (=24 hours × 90 days), the servo tape distance d after T hours can be approximated by the coefficients α and β determined by the least squares method using the following equation (3).

[0173] d = α × log e T×β……(3) In this embodiment, with T = 24 hours × 365 days × 10 years, the servo tape distance d (hereinafter referred to as "the distance of the first 10-year storage") for the read position x2 of the tape after a certain storage period and the servo tape distance d (hereinafter referred to as "the distance of the second 10-year storage") for the read position x3 of the tape after a certain storage period are calculated according to equation (3). Then, the function representing the correlation between the coordinates of the read position x1 and the servo tape distance d = "0", the coordinates of the read position x2 and the distance of the first 10-year storage, and the coordinates of the read position x3 and the distance of the second 10-year storage become the storage post-function 62. The storage post-function 62 is used as management information 15 (see reference). Figure 2 A portion of it is stored in cassette memory 26.

[0174] The servo tape distance d corresponding to the read position x2 of the tape after a certain storage period, i.e., the distance after the first 10-year storage period, is distance d1A. The distance after the first 10-year storage period is equivalent to the sum of the distance of the first 0-month storage period (= distance d1) and the change Δd1. The servo tape distance d corresponding to the read position x3 of the tape after a certain storage period, i.e., the distance after the second 10-year storage period, is the sum of distance d1A and distance d2A (= distance d2 + change Δd2) (cumulative value).

[0175] As an example, such as Figure 16 As shown, the processing device 30 retrieves the stored function 62 from the cassette memory 26. The processing device 30 creates a primary function 64 based on the stored function 62. The primary function 64 is a function representing the correlation between the coordinates of the read position x1 and the servo band distance d = "0" and the coordinates of the read position x3 and the distance of the second stored 10 years. Figure 16 In the example shown, a linear function 64 is illustrated as an example of a linear function 64, connecting the coordinates representing the distance between read position x1 and the servo band distance d = "0" and the coordinates representing the distance between read position x3 and the second storage period of 10 years. Linear function 64 is a function where the servo band distance d is proportional to the read position x. Furthermore, linear function 64 is a function representing the correlation between the distances of servo bands SB1 and SB2 and SB3 respectively, given that read positions x1, x2, and x3 are arranged at constant intervals in the width direction WD.

[0176] Here, the difference between the storage function 62 and the linear function 64 in the vertical axis direction (i.e., the difference between the servo tape distance d of the storage function 62 and the servo tape distance d of the linear function 64) represents the degree to which the position of the data playback element DR of the magnetic tape after a certain storage period deviates from its predetermined position in the width direction WD due to the influence of TDS. Therefore, in this embodiment, the difference between the storage function 62 and the linear function 64 in the vertical axis direction is defined as the data playback error B(x) caused by the influence of TDS.

[0177] As an example, such as Figure 17 As shown, the processing device 30 creates an adjusted linear function 66 by fitting the linear function 64 to the stored function 62 using the least squares method.

[0178] Here, the absolute value of the difference between the stored function 62 and the adjusted linear function 66 at reading position x1 along the vertical axis (i.e., the absolute value of the error B(x) at reading position x1) is defined as |B SB1The absolute value of the difference between the stored function 62 and the adjusted linear function 66 at reading position x2 along the vertical axis (i.e., the absolute value of the error B(x) at reading position x2) is defined as |B SB2 The absolute value of the difference between the stored function 62 and the adjusted linear function 66 at read position x3 along the vertical axis (i.e., the absolute value of the error B(x) at read position x3) is defined as |B|. SB3 |. For example Figure 17 As shown, between the stored function 62 and the adjusted linear function 66, |B SB1 |=|B SB2 |=|B SB3 |Established.

[0179] Next, refer to Figures 17-20 This section illustrates an example of how actual TDS reduction control can be implemented. As an example, for instance... Figure 17 As shown, |B SB1 |=|B SB2 |=|B SB3 |can be replaced with|PES SB1 |=|PES SB2 |=|PES SB3 |。 That is, |B SB1 |=|B SB2 |=|B SB3 The meaning of | and PES SB1 |=|PES SB2 |=|PES SB3 The meaning of | is the same. For ease of explanation, PES will be used without distinction below. SB1 PES SB2 and PES SB3 In this case, it is called "PES" SB ".

[0180] Here, |PES SB1 | refers to the absolute value of PES corresponding to servo band SB1. PES corresponding to servo band SB1 refers to the difference between the actual position and the ideal position of the read position x1 read by servo read element SR3. As |PES SB1One example is the absolute value of the difference between the current position of the servo read element SR3 and the first target read position (in other words, the offset in the width direction WD). Here, the current position of the servo read element SR3 refers to the current location of the servo read element SR3. And the first target read position refers to the read position that becomes the target to be read by the servo read element SR3 within the servo pattern 54 of the servo band SB1 when the data playback element DR is aligned with the track DT_N specified by the user (i.e., when playing back data from the segmented data track DT_N specified by the user).

[0181] |PES SB2 | refers to the absolute value of PES corresponding to servo band SB2. PES corresponding to servo band SB2 is the difference between the actual position and the ideal position of the read position x2 read by servo read element SR2. |PES SB2 One example is the absolute value of the difference between the current position of the servo read element SR2 and the second target read position (in other words, the offset in the width direction WD). Here, the current position of the servo read element SR2 refers to the current location of the servo read element SR2. And the second target read position refers to the read position that becomes the target to be read by the servo read element SR2 within the servo pattern 54 of the servo band SB2 when the data playback element DR is aligned with the track DT_N specified by the user (i.e., when playing back data from the segmented data track DT_N specified by the user).

[0182] |PES SB3 | refers to the absolute value of PES corresponding to servo band SB3. PES corresponding to servo band SB3 refers to the difference between the actual position and the ideal position of the read position x3 read by servo read element SR1. As |PES SB3 One example is the absolute value of the difference between the current position of the servo read element SR1 and the third target read position (in other words, the offset in the width direction WD). Here, the current position of the servo read element SR1 refers to the current location of the servo read element SR1. And the third target read position refers to the read position that becomes the target read by the servo read element SR1 within the servo pattern 54 of the servo band SB3 when the data playback element DR is aligned with the track DT_N specified by the user (i.e., when playing back data from the segmented data track DT_N specified by the user).

[0183] As a result of |PES SB1 |、|PES SB2 |and|PESSB3 The actual positions of X1, X2, and X3 read by the servo read elements SR3, SR2, and SR1 in |PES (i.e., as determined by the actual positions of X1, X2, and X3 read by the servo read elements SR3, SR2, and SR1 in |PES) SB The actual position of the read position X read by the servo read element SR in |PES| is determined using the following equation (4). In equation (4), the current position of the servo read element refers to the position of the read position X as determined by |PES|. SB The actual position of the read position X read by the servo read element SR in the |.

[0184] [Formula 1] exist Figure 18 The diagram shows a conceptual diagram of the variables used in equation (4) to illustrate the current position of the servo read element SR in order to determine the current position of the servo read element SR when the magnetic tape MT is traveling in the forward direction.

[0185] In equation (4), "α1" is a predetermined angle formed by the virtual straight line C1 and the linear magnetized region 54A1. In equation (4), "α2" is a predetermined angle formed by the virtual straight line C1 and the linear magnetized region 54A2. Furthermore, in this embodiment, since the linear magnetized regions 54A1 and 54A2 are symmetrically inclined with respect to the virtual straight line C1, "α1" and "α2" are the same value.

[0186] In equation (4), "i" is a natural number from 1 to 4. The maximum value of "i" (4 in this case) is the number of magnetization lines 54A1a used in the PES measurement. In equation (4), "A i"" refers to the distance between magnetized lines 54A1a and 54A2a at corresponding positions when the servo read element SR traverses the servo pattern 52A along the length direction LD. Here, "magnetized lines 54A1a and 54A2a at corresponding positions" refers to the first to fourth pairs of magnetized lines. The first pair of magnetized lines refers to the magnetized lines 54A1a and 54A2a located on the upstream side of the magnetic tape MT in the tape transport direction of each of the linear magnetized regions 54A1 and 54A2. The second pair of magnetized lines refers to the distance between the linear magnetized regions 54A1 and 54A2... The first pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located at the second position from the upstream side to the downstream side in the direction of tape MT in each of the linear magnetization regions 54A1 and 54A2. The second pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located at the third position from the upstream side to the downstream side in the direction of tape MT in each of the linear magnetization regions 54A1 and 54A2. The third pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located at the fourth position from the upstream side to the downstream side in the direction of tape MT in each of the linear magnetization regions 54A1 and 54A2.

[0187] In equation (4), "Bi" refers to the distance between the magnetized lines 54A1a and 54B1a at their corresponding positions when the servo read element SR traverses the servo pattern 52A and the servo pattern 52B adjacent to the servo pattern 52A on the positive side along the length direction LD. Here, "magnetized lines 54A1a and 54B1a at their corresponding positions" refers to the 5th to 8th pairs of magnetized lines. The 5th pair of magnetized lines refers to the magnetized lines 54A1a and 54B1a located on the upstream side of the magnetic tape MT in the tape transport direction within the linear magnetized region 54A1 in the servo pattern 52A and the linear magnetized region 54B1 in the servo pattern 52B adjacent to the servo pattern 52A on the positive side, respectively. The sixth pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a located at the second position from the upstream side to the downstream side in the tape transport direction of the magnetic tape MT, respectively, in the linear magnetization region 54A1 within the servo pattern 52A and the linear magnetization region 54B1 within the servo pattern 52B adjacent to the servo pattern 52A on the positive side. The seventh pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a located at the third position from the upstream side to the downstream side in the tape transport direction of the magnetic tape MT, respectively, in the linear magnetization region 54A1 within the servo pattern 52A and the linear magnetization region 54B1 within the servo pattern 52B adjacent to the servo pattern 52A on the positive side. The 8th pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a located at the 4th position from the upstream side to the downstream side in the linear magnetization region 54A1 in the servo pattern 52A and the linear magnetization region 54B1 in the servo pattern 52B adjacent to the servo pattern 52A on the positive side, respectively.

[0188] In equation (4), "d" is a distance predetermined as the distance between the linear magnetized region 54A1 and the linear magnetized region 54B1 along the length direction LD. As an example of "d", it can be the distance predetermined as the distance between the magnetized lines 54A1a and 54B1a at their corresponding positions when the servo reading element SR crosses the servo patterns 52A and 52B along the length direction LD.

[0189] Furthermore, here we have given an example of using Equation (4) to measure the PES in servo pattern 52A when the magnetic tape MT is traveling in the forward direction, but Equation (4) can also be used to measure the PES in servo pattern 52B. In this case, "B" i "" refers to the distance between the magnetization lines 54B1a and 54A1a at their corresponding positions when the servo reading element SR spans the servo pattern 52B and the servo pattern 52A adjacent to the servo pattern 52B on the positive side along the length direction LD.

[0190] “A i "and "B i "The determination is based on the servo pattern signal obtained by reading the servo pattern 52 by the servo reading element SR. In" Figure 18 In the example shown, regarding "PES" SB When the center position of the servo pattern 52 in the width direction WD (for example, the position where the virtual straight line C5 passing through the center of the servo pattern 52 in the width direction WD intersects with the servo pattern 52 along the length direction LD) is set to "0", the position in the servo pattern 52 that is closer to the first direction WD1 side than the virtual straight line C3 is represented as a positive value, and the position in the servo pattern 52 that is closer to the second direction WD2 side than the virtual straight line C3 is represented as a negative value.

[0191] As an example, such as Figure 19 As shown, the processing device 30 has an arithmetic expression 68. The processing device 30 uses |PES SB1 |、|PES SB2 |and|PES SB3 The servo control value is calculated using formula 68, which sets the servo control value as the independent variable and the servo control value as the dependent variable. Furthermore, the processing unit 30 performs servo control using the servo control value calculated using formula 68, thereby enabling |PES... SB1 |、|PES SB2 |and|PES SB3 Equalization control.

[0192] Examples of servo control values ​​include tilt angle, tension, and displacement. Here, tilt angle refers to the angle at which the magnetic head 28 tilts relative to the width direction WD of the magnetic tape MT towards the length direction LD of the magnetic tape MT. Tension refers to the tension applied to the length direction LD of the magnetic tape MT. Displacement refers to the amount by which the magnetic head 28 is displaced in the width direction WD.

[0193] The processing device 30 performs servo control based on skew control calculated using formula 68, tension control calculated using formula 68, and displacement control calculated using formula 68. Skew control is the control that causes the magnetic head 28 to skew on the magnetic tape MT, tension control is the control that applies tension to the magnetic tape MT to adjust the width of the magnetic tape MT, and displacement control is the control that causes the magnetic head 28 to move along the width direction WD on the magnetic tape MT.

[0194] To be more specific, the processing device 30 controls the tilting mechanism 49 such that the tilt angle of the magnetic head 28 relative to the width direction WD of the magnetic tape MT towards the length direction LD of the magnetic tape MT is the tilt angle calculated using formula 68. Furthermore, the processing device 30 controls the feed motor 36 and the rewind motor 40 such that the tension of the magnetic tape MT in the length direction LD is the tension calculated using formula 68. Moreover, the processing device 30 controls the moving mechanism 48 such that the displacement of the magnetic head 28 in the width direction WD is the displacement calculated using formula 68.

[0195] Thus, by performing skew control based on the tilt angle calculated using formula 68, tension control based on the tension calculated using formula 68, and displacement control based on the displacement amount calculated using formula 68, |PES SB1 |、|PES SB2 |and|PES SB3 |Equalization. Thus, the data playback element DR is aligned with the track on the segmented data track DT_N specified by the user, etc.

[0196] Additionally, here are examples of ways to make |PES SB1 |、|PES SB2 |and|PES SB3 This is an example of a method for skew control, tension control, and displacement control using equalization, but it is only one example; it can also be used to achieve PES. SB1 |、|PES SB2 |and|PES SB3 |Use equalization to perform one or two of the following controls: skew control, tension control, and displacement control.

[0197] Next, refer to Figure 19 An example of the process for reducing the impact of TDS performed by the processing unit 30 will be described. Additionally, Figure 20 The TDS reduction treatment shown is an example of the "treatment" involved in this invention. Furthermore, Figure 20 The TDS impact reduction process shown is an example of the "control method" involved in this invention.

[0198] exist Figure 20 In the TDS impact reduction process shown, firstly, in step ST10, the processing device 30 calculates multiple absolute values ​​of the differences, namely, |PES SB1 |、|PES SB2 |and|PES SB3 After the processing in step ST12 is performed, the TDS impact reduction process is transferred to step ST14.

[0199] In step ST12, the processing device 30 makes the |PES calculated in step ST10... SB1 |、|PES SB2 |and|PES SB3 The servo control value is calculated in a way that makes each other the same value. That is, by performing the processing in step ST14, the servo control value is calculated to make |PES SB1 |、|PES SB2 |and|PES SB3 |Equalized servo control values. After performing the processing in step ST14, the TDS impact reduction processing is transferred to step ST14.

[0200] In step ST14, the processing unit 30 performs servo control based on the servo control value calculated in step ST12. After executing the processing in step ST14, the TDS impact reduction processing ends.

[0201] As explained above, in this embodiment, the processing device 30 performs the |PES SB1 |、|PES SB2 |and|PES SB3 |Equalized servo control. This allows the servo read element SR3 to be aligned with the servo pattern 52 within servo tape SB1, the servo read element SR2 with respect to the servo pattern 52 within servo tape SB2, and the servo read element SR1 with respect to the servo pattern 52 within servo tape SB3, all according to predetermined design positions. Consequently, the data playback element DR can be aligned with the multiple segmented data tracks DT_N, thus improving the accuracy of playing back data recorded on the magnetic tape MT.

[0202] Furthermore, in this embodiment, data is recorded on the magnetic tape MT using SMR (Single Magnetic Recording) to form multiple segmented data tracks DT_N. Thus, even when data is recorded on the magnetic tape MT using SMR, by performing |PES (Performance-Restricted Spectroscopy)... SB1 |、|PES SB2 |and|PES SB3 Equal servo control also enables the servo read element SR to align its read position relative to the servo pattern 52 within the servo tape SB with the predetermined position determined by the design. As a result, the data playback element DR can be aligned with the multiple segmented data tracks DT_N obtained by recording data on the magnetic tape MT in an SMR manner, thus helping to improve the accuracy of playing back data recorded on the magnetic tape MT.

[0203] [Other variations] In the above embodiments, as an example of a magnetic tape stored for a certain period of time, a magnetic tape with data records stored for 10 years is shown. However, this is just one example. A magnetic tape with data records stored for a certain period of time can also be a magnetic tape with data records stored for a period of less than 10 years (e.g., a few seconds, minutes, hours, weeks, months, or years), or a magnetic tape with data records stored for a period of more than 10 years (e.g., more than ten years).

[0204] In the above embodiments, it is exemplified that |PES SB1 |、|PES SB2 |and|PES SB3 |Equalized servo control, but the same effect can be achieved through other methods. For example, it can also be set as follows: After storing the magnetic tape MT for a certain period of time, control to reduce the influence of the TDS of the magnetic tape MT is performed by using a storage post-function 62 and an adjusted linear function 66, which represent the correlation between the distances of the servo tape SB1 and other servo tapes SB after the storage period and the positions of the servo read elements SR1, SR2, and SR3 (i.e., read positions x1, x2, and x3). At this time, it is only necessary to perform the control that makes the TDS of the magnetic tape MT equalized. Figure 17 The saved function 62 and Figure 17 Servo control can be achieved by equalizing the absolute values ​​of the errors B(x) at the reading positions x1, x2, and x3 obtained from the adjusted linear function 66 shown.

[0205] By performing this servo control, the reading positions of servo read element SR3 relative to the servo pattern 52 within servo tape SB1, servo read element SR2 relative to the servo pattern 52 within servo tape SB2, and servo read element SR1 relative to the servo pattern 52 within servo tape SB3 can be aligned with predetermined positions determined in the design. As a result, the data playback element DR can be aligned with multiple segmented data tracks DT_N, thus helping to improve the accuracy of playing back data recorded on magnetic tape MT.

[0206] In the above implementation, in order to represent |B SB1 |=|B SB2 |=|B SB3 |and|PES SB1 |=|PES SB2 |=|PES SB3 The relationship between them is illustrated by the example of the processing device 30 creating and storing the function 62, the linear function 64, and the adjusted linear function 66. However, in practice, it is also possible to avoid creating the function 62, the linear function 64, and the adjusted linear function 66, as long as |PES is used. SB1 |=|PES SB2|=|PES SB3 Equalized servo control is sufficient.

[0207] The above embodiment illustrates a magnetic tape MT and a magnetic head 28, but this is only one example; for example, such as... Figure 21 As shown, magnetic tape MT1 and magnetic head 28A can also be used instead of magnetic tape MT and magnetic head 28. The difference between magnetic tape MT1 and magnetic tape MT is that it has a data tape DB0 and a servo tape SB0. Data tape DB0 is adjacent to servo tape SB1 in the width direction WD, separated by servo tape SB1. Servo tape SB0 is adjacent to servo tape SB1 in the width direction WD, separated by data tape DB0. The structure of servo tape SB0 is the same as that of servo tape SB described in the above embodiment, and the structure of data tape DB0 is the same as that of data tape DB described in the above embodiment.

[0208] The difference between magnetic head 28A and magnetic head 28 is that magnetic element unit 42A replaces magnetic element unit 42. The difference between magnetic element unit 42A and magnetic element unit 42 is that magnetic element unit 42A has four servo read elements SR as multiple magnetic elements, and has more data recording and playback elements DRW compared to magnetic element unit 42. The four servo read elements SR are servo read elements SR1, SR2, SR3, and SR4.

[0209] The structure of the servo read element SR4 is the same as that of the servo read element SR described in the above embodiment. The servo read element SR4 serves the servo tape SB0. In the width direction WD, a plurality of data recording playback elements DRW are disposed between the servo read element SR3 and the servo read element SR4. The plurality of data recording playback elements DRW disposed between the servo read element SR3 and the servo read element SR4 serve the data tape DB0.

[0210] When using this magnetic tape MT1 and magnetic head 28A, the read position x will also increase by an amount comparable to the increase in the servo tape SB, but as long as the absolute values ​​of the multiple differences (i.e., |PES) are calculated using the same method as in the above-described implementation, the absolute values ​​of the multiple differences (i.e., |PES) will be increased. SB1 |、|PES SB2 |、|PES SB3 |and|PES SB4 |) Equalized servo control can be achieved.

[0211] in addition, Figure 21 The structure of the MT1 magnetic tape shown is only one example. Even if a magnetic tape has more servo tapes (SB) and more data tapes (DB) than the MT1 magnetic tape, the invention still applies. Furthermore, Figure 21 The structure of the magnetic head 28A shown is just one example; the number of magnetic components mounted on the magnetic head 28A can be greater than... Figure 20The number of magnetic elements shown is large, and multiple magnetic elements can be mounted on the magnetic head 28A according to the principles described in the above embodiments.

[0212] In the above embodiments, examples were given of methods for calculating the servo band distance d between servo bands SB1 and SB2, and between servo bands SB1 and SB3, but this is only one example. For example, servo bands SB other than servo band SB1 can be positioned as reference servo bands SB to calculate the servo band distance d. For example, servo band SB3 can be positioned as a reference servo band SB to calculate the servo band distance d between servo band SB3 and SB2, and between servo band SB3 and SB1.

[0213] In the above embodiments, a magnetic tape system 10 in which the tape cartridge 12 can be freely inserted and removed from the tape drive 14 is illustrated, but the present invention is not limited thereto. For example, the present invention also applies to a magnetic tape system in which at least one tape cartridge 12 is pre-loaded into the tape drive 14 (i.e., a magnetic tape system in which at least one tape cartridge 12 and the tape drive 14 are pre-integrated).

[0214] In the above embodiment, a single magnetic head 28 is illustrated, but the present invention is not limited thereto. For example, multiple magnetic heads 28 may be located on the magnetic tape MT. For example, a read magnetic head 28 and at least one write magnetic head 28 may be located on the magnetic tape MT. The read magnetic head 28 can be used to verify data recorded on the data tape DB by the write magnetic head 28. Furthermore, a single magnetic head equipped with a read magnetic element unit 42 and at least one write magnetic element unit 42 may be located on the magnetic tape MT.

[0215] In the above embodiments, a function 60 (see reference) is created to easily visually grasp the difference between the servo tape distance d obtained from the tape before data recording and the servo tape distance d obtained from the tape after a certain storage period. Figure 15 This is just one example; the invention is valid even without creating the pre-save function 60.

[0216] In the above embodiments, a processing device 30 implemented by an ASIC is illustrated, but this is merely one example. For example, such as Figure 22 As shown, a computer 70, including a processor 70A (e.g., CPU), an NVM 70B, and RAM 70C, can also be used instead of the processing device 30 to perform the operation. Figure 20 The TDS effect reduction process shown is illustrated.

[0217] At this time, for example, program 72 can be stored in a computer-readable and non-transitory storage medium 74. Examples of storage medium 74 include SSDs or USB storage devices. Storage medium 74 can be a fixed storage medium or a portable storage medium.

[0218] Program 72, stored in storage medium 74, is installed in computer 70. Processor 70A executes TDS effect reduction processing according to program 72. Additionally, in Figure 22 In the examples shown, program 72 is an example of a "program" as understood in this invention, computer 70 is an example of a "computer" as understood in this invention, and processor 70A is an example of a "processor" as understood in this invention.

[0219] Furthermore, the program 72 can also be stored in a storage device such as another computer or server connected to the computer 70 via a network, and the program 72 can be downloaded and installed on the computer 70 upon request.

[0220] In addition, it is not necessary to store the entire program 72 in a storage device such as another computer or server connected to the computer 70, or to store the entire program 72 in the storage device 70B; a portion of the program 72 may also be stored.

[0221] As the hardware resource for performing TDS impact reduction processing, various processors, as shown below, can be used. For example, a general-purpose processor, i.e., a CPU, can function as the hardware resource for performing TDS impact reduction processing by executing software, i.e., a programmable programmable circuit, such as an FPGA, PLD, or ASIC, can also be used as a processor. All processors have built-in or connected memory, and all processors perform TDS impact reduction processing using this memory.

[0222] The hardware resources for performing TDS impact reduction processing can consist of one of these various processors, or a combination of two or more processors of the same or different types (e.g., a combination of multiple FPGAs, or a combination of a CPU and an FPGA). Furthermore, the hardware resources for performing TDS impact reduction processing can be a single processor.

[0223] As an example of a single processor, firstly, there is a method where a processor is composed of a combination of one or more CPUs and software, and this processor functions as the hardware resource for performing TDS impact reduction processing. Secondly, there is a method, such as a System-on-a-Chip (SoC), where a single IC chip is used to implement the overall system functionality, including multiple hardware resources performing TDS impact reduction processing. In this way, TDS impact reduction processing is implemented using one or more of the aforementioned processors as hardware resources.

[0224] Furthermore, the hardware architecture of these various processors, more specifically, can utilize circuits composed of combined semiconductor elements and other circuit components. Moreover, the aforementioned TDS impact reduction process is merely one example. Therefore, it is certainly possible to remove unnecessary steps, add new steps, or change the processing order without departing from the main point.

[0225] The descriptions and illustrations shown above are a detailed explanation of the parts involved in this invention, and are merely one example of this invention. For example, the descriptions related to the above structure, function, effect, and effect are examples of the structure, function, effect, and effect of the parts involved in this invention. Therefore, it is natural that unnecessary parts can be deleted, new elements can be added, or substitutions can be made to the descriptions and illustrations shown above without departing from the spirit of this invention. Furthermore, in order to avoid being cumbersome and to facilitate understanding of the parts involved in this invention, descriptions of technical common sense that do not require special explanation in implementing this invention have been omitted from the descriptions and illustrations shown above.

[0226] In this specification, "A and / or B" has the same meaning as "at least one of A and B". That is, "A and / or B" means that it can be only A, only B, or a combination of A and B. Furthermore, in this specification, when three or more cases are connected by "and / or", the same consideration method as "A and / or B" can be applied.

[0227] All documents, patent applications and technical standards described in this specification may be referenced in this specification to the same extent as the specific and individually described instances of reference to each document, patent application and technical standard.

[0228] The following notes are also disclosed regarding the above implementation methods.

[0229] (Note 1) A control device comprising a processor, The aforementioned processor performs TDS (Total Distance Detection) reduction control on the magnetic tape, which contains three or more servo tapes arranged along its width. Each of these servo tapes records multiple servo patterns along its length, and data tapes are formed between the three or more servo tapes along the width direction. The aforementioned TDS reduction control is achieved by using the first function and the second function to reduce the TDS impact of the magnetic tape. The first function described above represents the correlation between the positions of the three or more reading elements in the arrangement direction and the following first distances when three or more reading elements are used to read the three or more servo tapes in parallel by means of three or more reading elements arranged in a straight line. Each first distance is the distance between the reference servo tape (i.e., the reference servo tape) and each of the three or more servo tapes after the tape has been stored. The second function described above represents the correlation between the aforementioned positions and the following second distances, which are the distances between the aforementioned reference servo band and each of the aforementioned three or more servo bands, provided that the aforementioned three or more servo bands are arranged at constant intervals in the width direction. The TDS impact reduction control described above is a control that equalizes the offsets between the positions determined by the first function and the positions determined by the second function.

[0230] (Note 2) According to the control device described in Appendix 1, wherein... The aforementioned TDS impact reduction control is a control that equalizes the aforementioned offsets through servo control.

[0231] (Note 3) A magnetic tape system comprising: The control device described in Appendix 1 or 2; and the magnetic head, for recording data on the magnetic tape and / or playing back the data recorded on the magnetic tape.

[0232] (Note 4) According to Appendix 3, the magnetic tape system includes the aforementioned magnetic tape.

[0233] (Note 5) A control method includes the following steps: performing TDS (Total Distance Detection) effect reduction control on a magnetic tape, wherein three or more servo tapes are arranged along the width direction, each of the three or more servo tapes records multiple servo patterns along the length direction, and data tapes are formed between the three or more servo tapes along the width direction. The aforementioned TDS reduction control is achieved by using the first function and the second function to reduce the TDS impact of the magnetic tape. The first function described above represents the correlation between the positions of the three or more reading elements in the arrangement direction and the following first distances when three or more reading elements are used to read the three or more servo tapes in parallel by means of three or more reading elements arranged in a straight line. Each first distance is the distance between the reference servo tape (i.e., the reference servo tape) and each of the three or more servo tapes after the tape has been stored. The second function described above represents the correlation between the aforementioned positions and the following second distances, which are the distances between the aforementioned reference servo band and each of the aforementioned three or more servo bands, provided that the aforementioned three or more servo bands are arranged at constant intervals in the width direction. The TDS impact reduction control described above is a control that equalizes the offsets between the positions determined by the first function and the positions determined by the second function.

[0234] (Note 6) A program that causes a computer to perform processing. The above process includes the following steps: TDS (Total Distributed Data) effect reduction control is applied to a magnetic tape containing three or more servo tapes arranged along its width. Each of these servo tapes records multiple servo patterns along its length, and data tapes are formed between the three or more servo tapes along the width direction. The aforementioned TDS reduction control is achieved by using the first function and the second function to reduce the TDS impact of the magnetic tape. The first function described above represents the correlation between the positions of the three or more reading elements in the arrangement direction and the following first distances when three or more reading elements are used to read the three or more servo tapes in parallel by means of three or more reading elements arranged in a straight line. Each first distance is the distance between the reference servo tape (i.e., the reference servo tape) and each of the three or more servo tapes after the tape has been stored. The second function mentioned above represents the correlation between the above positions and the following second distances, which are the distances between the reference servo band and each of the above three or more servo bands under the condition that the above three or more servo bands are arranged at constant intervals in the width direction. The TDS influence reduction control is to control: equalize the offsets between the above positions determined according to the first function and the above positions determined according to the second function.

Claims

1. A control device comprising a processor, The processor performs TDS reduction control to reduce the TDS of the magnetic tape, in which three or more servo tapes are arranged along the width direction, each of which records multiple servo patterns along the length direction, and data tapes are formed between the three or more servo tapes along the width direction. The TDS impact reduction control is implemented as follows: the impact is reduced by equalizing the absolute values ​​of the differences obtained for the three or more read elements in the arrangement direction of the three or more read elements when the three or more read elements are read in parallel through the three or more read elements arranged in a straight line. The absolute value of the difference is the absolute value of the difference between the current position of the reading element and the target reading position of the reading element.

2. The control device according to claim 1, wherein, The TDS impact reduction control is a control that equalizes the absolute values ​​of the three or more differences through servo control.

3. A magnetic tape system, comprising: The control device according to claim 1 or 2; and A magnetic head is used to record data onto the magnetic tape and / or play back the data recorded on the magnetic tape.

4. The magnetic tape system according to claim 3, wherein the magnetic tape is included.

5. A control method comprising the following steps: TDS reduction control is performed to reduce the TDS impact of the magnetic tape. In this magnetic tape, three or more servo tapes are arranged along the width direction. Each of these three or more servo tapes records multiple servo patterns along its length direction, and data tapes are formed between the three or more servo tapes along the width direction. The TDS impact reduction control is implemented as follows: the impact is reduced by equalizing the absolute values ​​of the differences obtained from the three or more read elements when the three or more servo bands are read in parallel by three or more read elements arranged in a straight line. The absolute value of the difference is the absolute value of the difference between the current position of the reading element and the target reading position of the reading element.

6. A program for causing a computer to perform processing. The process includes the following steps: TDS reduction control is performed to reduce the TDS impact of the magnetic tape. In this magnetic tape, three or more servo tapes are arranged along the width direction. Each of these three or more servo tapes records multiple servo patterns along its length direction, and data tapes are formed between the three or more servo tapes along the width direction. The TDS impact reduction control is implemented as follows: the impact is reduced by equalizing the absolute values ​​of the differences obtained for the three or more read elements in the arrangement direction of the three or more read elements when the three or more read elements are read in parallel through the three or more read elements arranged in a straight line. The absolute value of the difference is the absolute value of the difference between the current position of the reading element and the target reading position of the reading element.

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