Method and device for operating a storage unit

Abstract

Method for operating a storage unit with a tape (TP) and a head (HU) which is functionally capable of reading data from the tape (TP) or writing data thereto, wherein the tape (TP) is movable in a predetermined longitudinal direction (X), wherein - at least two temporally consecutive current lateral belt positions (y,(t1), y,(t2)) of the belt (TP) are determined with respect to a predetermined reference point (REF) at a predetermined longitudinal detection position, - a belt skew (θ) of the belt (TP) depending on at least two determined lateral positions (y x (t1),y x (t2)), wherein the belt skew (θ) corresponds to an angle between a current belt movement direction (TMD) of the belt (TP) and the longitudinal direction (X), - a skew control signal (u ϑ ) is determined depending on the determined belt skew (θ), - a head rotation position (9) of the head (HU) depending on the skew control signal (u ϑ ) is controlled so that the head (HU) is aligned with the current tape movement direction (TMD) in such a way that the head (HU) is functionally capable of reading and / or writing data.

Description

FIELD OF EXPERTISE

[0001] The present invention relates to a method and apparatus for operating a storage unit comprising a tape and a head. BACKGROUND OF THE INVENTION

[0002] EP patent application 0 549 848 A1 describes detecting a tape edge and further controlling the read / write head to self-position on the detected edge. An array of photodetectors in a chip with an integrated circuit senses the intensity of the light illuminating the chip as the tape moves between a light source and the photodetectors.

[0003] US patent application 2006 / 0103968 A1 describes that, by increasing storage densities on a data carrier of a given cartridge size, the bits on the carrier can be written into smaller areas and onto a plurality of parallel longitudinal tracks. In this context, a system for positioning a transducer head relative to a data carrier is disclosed. First and second sensors are associated with the head such that they can be used to adjust an azimuth position of the head. The first and second sensors are arranged on opposite sides of the head along a direction of data carrier transport. The azimuth position of the head is adjusted in response to the positions of the carrier sensed by the first and second sensors.

[0004] As a result, it is a challenge to provide a method and apparatus for operating a storage device that enables reliable positioning of the head.

[0005] DE 694 15 063 T2 discloses a head track alignment system for use in magnetic recording tape drives that automatically corrects misalignment between the head assembly and a recorded servo track on the tape. Using a servo control loop, the system calculates the head track alignment error during tape drive operation and either pivots the head assembly or adjusts the tape cartridge to compensate for the error. The system also includes mechanisms for transversely positioning the head track to center the heads on the servo track and hold them in that position.

[0006] US 6,430,008 B1 discloses a system for positioning a tape head relative to a magnetic tape by accurately measuring the position error of the magnetic tape. The tape head includes at least one read module with two servo read elements. A head controller detects the presence of corresponding synchronization fields passing the servo read elements. The elapsed time between the detected synchronization fields is determined. The tape offset is calculated based on the elapsed time. To accurately calculate the tape position error, an additional servo read element can be installed on either a second read module or a write module. The tracking information read by two servo read elements scanning the same servo stripe is used to calculate the offset between a read module and the write module.

[0007] US 2006 / 0 103 968 A1 discloses a system for positioning a transducer head on a storage medium. The system comprises a transducer head assembly with read / write elements, at least one actuator for adjusting the azimuth position of the transducer head, first and second position sensors, and a controller. The first and second sensors detect a reference associated with a position of the storage medium, wherein the first and second sensors are arranged on opposite sides of the read / write elements of the transducer head along a transport direction of the storage medium. The controller adjusts the azimuth position of the transducer head in response to the positions of the reference detected by the first and second sensors. The at least one actuator can comprise differential actuators. The adjustments of the transducer head can be made dynamically during the read and write process.

[0008] DE 692 25 945 T2 discloses a method and a device designed for detecting a tape edge and controlling the read / write head to position itself relative to the detected edge. An array of photodetectors in an integrated circuit detects the intensity of the light illuminating the chip, with the tape passing between the light source and the photodetectors. This creates a light-dark transition that indicates the edge of the tape. SUMMARY OF THE INVENTION

[0009] The objects underlying the invention are achieved by the features of the independent patent claims. Embodiments of the invention are the subject of the dependent patent claims.

[0010] According to a first and second aspect of the invention, a method and associated apparatus for operating a storage unit having a tape and a head are described. The head is operatively capable of reading data from or writing data to the tape. The tape is movable in a predetermined longitudinal direction. Within the scope of a skew estimation of the tape, at least two consecutive current lateral positions of the tape relative to a predetermined reference point are determined at predetermined longitudinal detection positions. A tape skew of the tape is determined depending on the at least two determined lateral positions. The tape skew corresponds to an angle between a current tape movement direction of the tape and the longitudinal direction. A skew control signal is determined depending on the determined tape skew.A head rotation position of the head is controlled in response to the skew control signal to align the head with the current tape travel direction such that the head is functionally capable of reading and / or writing data.

[0011] This enables improved track following control, especially in the case of low-frequency lateral disturbances such as stack shifts. In this context, track following control involves controlling the lateral and head rotation position, moving and rotating the head to follow a centerline of the data tracks as accurately as possible, for example, during read / write operations.

[0012] The longitudinal direction and a predefined lateral direction serve as reference directions. Both directions are preferably perpendicular to each other. In this context, the term "lateral" corresponds to the transverse direction, and the term "longitudinal" corresponds to the longitudinal direction.

[0013] For example, the tape can be fed from a supply reel and taken up by a take-up reel. Tape transport is initiated by starting at least the take-up reel to move the tape in a predetermined tape transport direction. The tape movement direction primarily comprises longitudinal movement components, but can also include transverse movement components, which can be referred to as lateral tape movement. Lateral tape movement can arise, for example, from the accumulation of wear on flange rollers or from uneven winding or unwinding of the tape, and it can correspond, for example, to sudden lateral displacements of the tape.

[0014] By using flangeless rollers in a storage unit's tape path, there is no tight restriction on tape movement, and lateral tape movement is more pronounced. In a flangeless drive, the amplitude of these disturbances is higher than in a drive with flanged rollers. The increased amplitude of lateral tape movement typically creates a large skew between the tape and the head, degrading system performance. Stack shifts appear as sudden lateral displacements that repeat at the same longitudinal position each time the tape is run.

[0015] The at least two consecutive lateral belt positions are determined at a predefined longitudinal detection position. The longitudinal detection position corresponds to a position along the belt path.

[0016] For example, the head must be aligned perpendicular to the direction of tape movement to enable reading and / or writing of data.

[0017] In a preferred embodiment of the first and second aspects of the invention, at least one tilt element of the storage unit is controlled in response to the skew control signal to align the tape travel direction of the tape with the head such that the head is functionally capable of reading and / or writing data. Tilting the tape may be accomplished using tilt elements such as tape rollers, which may, for example, be deployed to tilt longitudinally in response to the skew control signal. Tilting the tape may be used in conjunction with head rotation.

[0018] According to a third and fourth aspect of the invention, a method and associated apparatus for operating a storage unit having at least one tilt element and a tape and a head are described. The head can be used to read or write data from or to the tape, wherein the tape is movable in a predetermined longitudinal direction. Within the scope of a tape skew evaluation, at least two consecutive current lateral tape positions of the tape are determined with respect to a predetermined reference point at a predetermined longitudinal detection position. A tape skew of the tape is determined depending on the at least two determined lateral positions. The tape skew corresponds to an angle between a current tape movement direction of the tape and the longitudinal direction. A skew control signal is determined depending on the determined tape skew.The at least one tilt element is controlled in response to the skew control signal to align the tape's direction of travel relative to the head in such a way that the head is functionally capable of reading and / or writing data. This enables improved track following control, particularly in the case of low-frequency lateral disturbances such as stack shifts. The tilt elements may, for example, be tape rollers in contact with the tape and may be used to tilt the tape, for example, longitudinally, in response to the skew control signal. Tilting the tape may be used in combination with head rotation.

[0019] In a preferred embodiment of the preceding aspects of the invention, at least one strip edge of the strip is observed. The at least two consecutive lateral strip positions are determined depending on the at least one observed strip edge. This facilitates reliable determination of the current lateral strip position. The observation of the strip edge is preferably implemented using optical sensors.

[0020] In a further preferred embodiment of the preceding aspects of the invention, a predetermined position error signal is observed corresponding to a lateral distance between the head and a predetermined reference position on a particular servo pattern of predetermined servo patterns stored on the tape along a longitudinal extent of the tape. The at least two consecutive lateral tape positions are determined depending on the observation of the predetermined position error signal. The position error signal is typically provided by the head. This has the advantage that no external sensors are used to enable tape skew compensation. The respective servo pattern corresponds, for example, to written servo stripes and is preferably written onto the tape during tape manufacture.

[0021] In a further preferred embodiment of the preceding aspects of the invention, the at least two consecutive lateral tape positions are determined depending on a predetermined model of an actuator to which the position error signal is applied. The actuator is operatively capable of controlling at least one lateral head position of the head. This facilitates the determination of the at least two consecutive lateral tape positions depending on the position error signal, which is acquired, for example, by a closed-loop control system.

[0022] In a further preferred embodiment of the preceding aspects of the invention, a tape transport direction of the tape is determined in the longitudinal direction. The longitudinal detection position is determined depending on the tape transport direction in such a way that the tape first passes the longitudinal detection position and then the head and / or the at least one inclination element.

[0023] Lateral disturbances originating at a specific location along the tape path typically propagate from one point to another along the tape path. The lateral tape position, determined, for example, by the sensor arranged in front of the head and / or the at least one tilt element at the longitudinal detection position with respect to the tape transport direction, appears at the location of the head or at the longitudinal position of the tilt element with a time delay that depends on a tape speed and a longitudinal distance between the longitudinal detection position and the longitudinal position of the head or the longitudinal position of the respective tilt element. This facilitates a proper assessment of the lateral tape movement at the longitudinal position of the head and / or the longitudinal position of the respective tilt element.

[0024] In a further preferred embodiment of the preceding aspects of the invention, the tape skew evaluation is performed cyclically. This facilitates skew compensation during operation of the storage unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention and its embodiments will be more fully understood by reference to the following detailed description of the presently preferred, yet illustrative embodiments according to the present invention when read in conjunction with the accompanying drawings.

[0026] The figures illustrate: Fig. 1 an exemplary illustration of a tape path; Fig. 2 a diagram; Fig. 3 an illustration of the head and the band; Fig. 4 an illustration of a control system; Fig. 5 a schedule.

[0027] Different figures may contain the same reference numerals, which represent elements with similar or equivalent content. DETAILED DESCRIPTION OF THE DRAWINGS

[0028] Fig. Figure 1 shows a tape path of a storage unit, such as a tape drive, in a schematic view. The tape path includes a head HU, for example, a magnetic head, and tape reels RR, RR1, RR2, such as flangeless reels. The head HU comprises at least a first and a second head module HM1, HM2. Each head module HM1, HM2 comprises at least one head element RW and at least one servo read element RE. Each head element RW is functionally designed to read data from or write data to a tape TP, and can be, for example, a read or write converter.

[0029] The band TP can, for example, comprise at least one servo pattern SP ( Fig. 3). The respective servo pattern SP is part of or belongs to data tracks of the tape TP, which correspond to a tape area in which the current data is stored and / or written. Each servo read element RE is functionally designed to detect and / or read the servo pattern SP. A predetermined selection of servo read elements RE is preferably assigned to the servo pattern SP.

[0030] The storage unit preferably comprises an actuator PU which is functionally capable of controlling a lateral head position y of the head HU in a lateral direction Y depending on a predetermined position control signal u y The actuator PU can also be functionally capable of controlling a head rotation position ϑ of the head HU ( Fig. 4) to be controlled in a plane defined by the longitudinal direction X and the lateral direction Y depending on a predetermined skew control signal u ϑ is determined in advance.

[0031] Furthermore, a first and a second tape reel RR1, RR2 are arranged next to the head HU on opposite sides of the head HU in the longitudinal direction X. The first and the second tape reel RR1, RR2 are in direct contact with the tape TP and are functionally capable of rotating the tape TP depending on a predetermined skew control signal u ϑ to actively tilt. For this purpose, the first and second belt rollers RR1, RR2 can be functionally designed to tilt in the longitudinal direction x. The first and second belt rollers RR1, RR2 are also referred to as tilting elements. The storage unit can comprise the actuator PU, which is functionally capable of controlling the rotational position ϑ of the belt TP and / or at least one tilting element, which is functionally capable of tilting the belt TP.

[0032] The band TP can move in a forward direction along a longitudinal direction X, as shown in Fig. 1. The forward direction corresponds to a belt transport direction TPDIR along the longitudinal direction X, where the belt TP first passes, for example, the first head module HM1 and then the second head module HM2. A reverse direction of the belt TP is the opposite of the forward direction.

[0033] The belt path includes a first sensor S1 at a first longitudinal position x1 and a second sensor S2 at a second longitudinal position x2, as shown in Fig. 1. Both sensors S1, S2 can be optical sensors, such as light barriers, photodetectors or an arranged group of photodetectors. The first and second sensors S1, S2 are arranged on opposite sides of the head HU with respect to the longitudinal direction X. Furthermore, the first sensor S1 and the second sensor S2 are arranged on opposite sides of the first and second tape rolls RR2, RR1. A first longitudinal distance L1 corresponds to a distance between the first longitudinal position x1 and the head HU. A second longitudinal distance L2 corresponds to a distance between the second longitudinal position x2 and the head HU. A further first longitudinal distance L1* corresponds to a distance between the first longitudinal position x1 and a further first longitudinal position x1* of the first tape roll RR1.A further second longitudinal distance L2* corresponds to a distance between the second longitudinal position x2 and a further second longitudinal position x2* of the second strip roll RR2. Each sensor S1, S2 is preferably capable of observing a strip edge E. The first sensor S1 is further capable of providing a first sensor output signal dependent on the observed strip edge E. The first sensor output signal corresponds to a first lateral strip position y. x1 (t) with respect to a predetermined reference point REF at the first longitudinal position x1. The second sensor S2 is functionally capable of providing a second sensor output signal dependent on the observed strip edge E. The second sensor output signal corresponds to a second lateral strip position y x2(t) with respect to a predetermined reference point REF at the second longitudinal position x2. The reference point REF can, for example, be a lateral position of the first and second sensors S1, S2. The first longitudinal position x1 and the second longitudinal position x2 are also referred to as longitudinal detection positions.

[0034] Fig. Figure 2 shows a graph depicting the lateral band movement over time t. It shows a signal curve of the first lateral band position y x1 (t) and a position error signal PES over time t. The first lateral band position y xl (t) is provided, for example, by the first sensor S1 at the first longitudinal position x1. The first lateral belt position y x1(t) and the position error signal PES change over time t due to the lateral belt movement introduced by lateral disturbances such as stack shifts. Due to the lateral belt movement of the belt TP, a resulting belt movement direction TMD (see also Fig. 3) also include movement components in the lateral direction Y. A belt skew θ corresponds to an angle between the resulting belt movement direction TMD and the longitudinal direction X (see also Fig. 3).

[0035] The position error signal PES is preferably provided by the head HU and preferably controlled by a control system ( Fig. 4). The position error signal PES corresponds to a lateral distance between a current lateral head position and a predefined reference position r y on a specific servo pattern at the longitudinal position x0 of the head. In the diagram in Fig. 2, the waveform of the position error signal PES represents a position error signal that is used in an open loop control system configuration according to Fig. 4. The open-loop control system configuration is, for example, given when the head HU is fixed to a predetermined lateral head position y, such as the reference point REF.

[0036] As in Fig. As can be seen in Figure 2, the signal curve of the first lateral band position y x1 (t) precedes the waveform of the position error signal PES and thereby indicates the forward direction of the moving belt TP. The time delay between the waveform of the first lateral belt position y x1(t) and the signal curve of the position error signal PES correlates with a time period in which a predetermined point of the belt TP passes the first longitudinal distance L1 at a predetermined belt speed v. The first lateral belt position y x1 (t) allows an evaluation of the lateral band position at the longitudinal position x0 of the head.

[0037] Fig. 3 shows the belt TP moving in the forward direction at the predetermined belt speed v. At a first time t1, a lateral belt position y x (t1) at a previously determined longitudinal detection position, such as by the first sensor S1 at the first longitudinal position x1. At a second time t2, another lateral belt position y x (t2) at the same predetermined longitudinal detection position. In the reverse direction, the lateral belt positions y x(t1), Y''(t2) can be determined, for example, by the second sensor S2 at the second longitudinal position x2.

[0038] Alternatively or additionally, both lateral band positions y x (t1), y x (t2) from certain lateral positions d y derived from the position error signal PES. The determined lateral position d y corresponds to a corresponding lateral tape position. As already mentioned, the position error signal PES is usually incorporated into a tracking control of the lateral head position y of the head HU. The tracking control can be implemented in a closed-loop control system, as in Fig. 4. As a result, usually only a closed-loop position error signal PES is available, which usually does not offer the possibility of determining the specific lateral position d y directly. The lateral position of they can, however, be calculated from a predetermined first parameter P yy a model P of an actuator PU and a predetermined controller gain K y of a controller KU, as in equation F2 in Fig. 4 shown.

[0039] In this context, the lateral band position y x (t1) from the lateral position d determined at the first time t1 y be derived, and the further lateral band position Y''(t2) can be calculated from a lateral position d determined at the second time t2 y The lateral position d determined at the first time t1 y can be equal to the lateral band position y x (t1). The lateral position d determined at the second time t2 y can be equal to the second lateral band position y x (t2). Both lateral band positions y x (t1), y x(t2) correspond to two determined consecutive lateral band positions.

[0040] The belt skew θ can be calculated using equation F0 in Fig. 3, which is a trigonometric relationship of the triangle ABΓΔ represents. A first triangle side d BΓ corresponds to the lateral distance between both determined lateral band positions y x (t1), y x (t2). A second triangle side d AB corresponds to a distance in the belt movement direction TMD, which results from the current belt speed v and a time difference Δt. The time difference Δt corresponds to a time delay between the first and second time points t1, t2.

[0041] According to Fig. 4, the actuator PU of the control system is functionally capable of moving the head HU depending on a predetermined position control signal u yto move at least laterally. The current lateral position of the head HU is represented by the lateral head position y. The position control signal u y is controlled by the controller KU depending on the predefined controller gain K y and the position error signal PES. The position error signal PES is calculated from a difference between the lateral position d y and the lateral head position y and the reference position r y derived from the respective servo pattern.

[0042] In addition, the actuator PU can be functionally designed to move the head HU depending on the skew control signal u ϑ The current rotational position of the head HU is represented by the head rotational position ϑ. The skew control signal u ϑ is controlled by the controller KU depending on a further predefined controller gain K ϑand a skew error signal SES. The skew error signal SES is calculated from the difference between the current tape skew θ and the head rotation position ϑ and a predetermined skew reference value r ϑ In addition to the controller KU, the control system may include a separate controller that generates the skew control signal u ϑ depending on the skew error signal SES. Alternatively or additionally, the skew control signal u ϑ the inclination elements, such as the first and second belt rollers RR1, RR2, to incline the belt TP accordingly.

[0043] Equation F2 in Fig. 4 refers to the Fig. 4. The model P of the actuator can, for example, be a 2x2 matrix, as shown in equation F4 in Fig. 4. Thus, the actuator model P corresponds to a system with two inputs and two outputs. The first parameter Pyy models a relationship between the lateral head position y and the position control signal u y . A second parameter P ϑϑ models a relationship between the head rotation position ϑ and the predetermined skew control signal u ϑ . The remaining parameters P yϑ , P ϑy provide a cross-coupling between the lateral head position y and the predefined skew control signal u ϑ and a cross-coupling between the head rotation position ϑ and the predefined position control signal u y represents.

[0044] A program according to the schedule of Fig. 5 is executed, for example, by a control unit of the storage unit, such as a microcontroller. The control unit may also be referred to as a device for operating the storage unit. The program in Fig. Figure 5 represents an evaluation of the belt skew.

[0045] The execution of the program begins in step S0. In step S2, the two consecutive lateral belt positions y x (t1), y x (t2). In addition, further lateral band positions can be determined. The at least two lateral band positions y x (t1), y x (t2) can be derived from the position error signal PES, for example by using the actuator model P and the predefined controller gain K y Alternatively or additionally, the at least two lateral band positions y x (t1), y x (t2) depending on the first or second lateral band position y x1 (t) , y x2 (t) provided by the first or second sensor S1, S2 depending on the tape transport direction TPDIR.

[0046] In a step S4, the tape skew θ is determined, for example, depending on the at least two lateral tape positions y x (t1), y x (t2) and the current belt speed v and the time difference Δt. The belt skew θ can be determined using equation F0 in Fig. 3 and calculating its arcsine.

[0047] In a step S6, the skew error signal SES is determined depending on the determined tape skew θ and the current head rotation position ϑ of the head HU.

[0048] In a step S8, the skew control signal u ϑ determined depending on the skew error signal SES. The head rotation position ϑ of the head HU is determined by the actuator P and / or the inclination elements depending on the determined skew control signal u ϑcontrolled so that the head HU is aligned with the current tape movement direction TMD in such a way that the head HU can be used to read and / or write data. Execution of the software program ends in step S10. Preferably, program execution and thus the evaluation of the tape skew begin again in step S2.

[0049] Although the invention has been described by way of several exemplary embodiments, the invention is not limited to these embodiments. It will be understood that various modifications and variations of the present invention will be possible for those skilled in the art without departing from the scope of the present invention. The present invention is intended to cover these modifications and variations, provided they fall within the scope of the following claims and their equivalents. LIST OF REFERENCE SYMBOLS

Claims

[1] A method for operating a storage unit comprising a tape (TP) and a head (HU) which is functionally capable of reading data from the tape (TP) or writing data thereto, the tape (TP) being movable in a predetermined longitudinal direction (X), wherein - at least two temporally consecutive current lateral belt positions (y,(t1), y,(t2)) of the belt (TP) are determined with respect to a predetermined reference point (REF) at a predetermined longitudinal detection position, - a belt skew (θ) of the belt (TP) depending on at least two determined lateral positions (y x (t1),y x (t2)), wherein the belt skew (θ) corresponds to an angle between a current belt movement direction (TMD) of the belt (TP) and the longitudinal direction (X), - a skew control signal (u ϑ ) is determined depending on the determined belt skew (θ), - a head rotation position (9) of the head (HU) depending on the skew control signal (u ϑ ) is controlled so that the head (HU) is aligned with the current tape movement direction (TMD) in such a way that the head (HU) is functionally capable of reading and / or writing data. [2] Method according to claim 1, wherein at least one inclination element of the storage unit is dependent on the skew control signal (u ϑ ) is controlled so that the tape movement direction (TMD) of the tape (TP) is aligned at the head (HU) in such a way that the head (HU) is functionally capable of reading and / or writing data. [3] A method for operating a storage unit comprising at least one tilting element, a tape (TP) and a head (HU) which is functionally capable of reading data from or writing data to the tape (TP), the tape (TP) being movable in a predetermined longitudinal direction (X), wherein - at least two consecutive current lateral band positions (y x (t1), y x (t2)) of the strip (TP) with respect to a predetermined reference point (REF) at a predetermined longitudinal detection position, - a belt skew (θ) of the belt (TP) depending on at least two determined lateral positions (y x (t1), y x (t2)), wherein the belt skew (θ) corresponds to an angle between a current belt movement direction (TMD) of the belt (TP) and the longitudinal direction (X), - a skew control signal (u ϑ ) is determined depending on the determined belt skew (θ), - the at least one inclination element depending on the skew control signal (u ϑ) is controlled so that the tape movement direction (TMD) of the tape (TP) is aligned at the head (HU) in such a way that the head (HU) is functionally capable of reading and / or writing data. [4] Method according to claim 3, wherein a head rotation position (9) of the head (HU) is determined depending on the skew control signal (u ϑ ) is controlled so that the head (HU) is aligned with the current tape movement direction (TMD) in such a way that the head (HU) is functionally capable of reading and / or writing data. [5] Method according to one of the preceding claims, wherein - at least one band edge (E) of the band (TP) is observed, - the at least two temporally consecutive lateral band positions (y x (t1),y x (t2)) depending on the at least one observed band edge (E). [6] The method of claim 5, wherein the at least one strip edge (E) is observed using at least one optical sensor. [7] Method according to one of the preceding claims, wherein - a predetermined position error signal (PES) is observed, which corresponds to a lateral distance between the head (HU) and a predetermined reference position (r y ) on a specific servo pattern (SP) of predefined servo patterns stored on the tape (TP) along a longitudinal extent of the tape (TP), - the at least two temporally consecutive lateral band positions (y x (t1), y x (t2)) depending on the observation of the predetermined position error signal (PES). [8] Method according to claim 7, wherein the at least two temporally successive lateral band positions (y x (t1),y x(t2)) are determined depending on a predetermined model (P) of an actuator (PU) to which the position error signal (PES) is applied, wherein the actuator (PU) is functionally capable of controlling at least one lateral head position (y) of the head (HU). [9] Method according to one of the preceding claims, wherein - a belt transport direction (TPDIR) of the belt (TP) in the longitudinal direction (X) is determined, - a longitudinal detection position is determined depending on the tape transport direction (TPDIR) in such a way that the tape (TP) first passes the longitudinal detection position and then the head (HU). [10] Method according to one of claims 2 to 9, wherein - a belt transport direction (TPDIR) of the belt (TP) in the longitudinal direction (X) is determined, - the longitudinal detection position is determined depending on the belt transport direction in such a way that the belt (TP) first passes the longitudinal detection position and then the at least one inclination element. [11] Method according to one of the preceding claims, wherein - a current belt speed (v) of the belt (TP) in the longitudinal direction (X) is determined, - the belt skew (θ) is determined depending on the determined belt speed (v). [12] Method according to one of the preceding claims, wherein the tape skew evaluation is carried out cyclically. [13] Device for operating a storage unit with a tape (TP) and a head (HU) which is functionally capable of reading data from the tape (TP) or writing data thereto, the tape (TP) being movable in a predetermined longitudinal direction (X), the device being functionally capable of - at least two consecutive current lateral band positions (y''(t1)1 y x (t2)) of the strip (TP) with respect to a predetermined reference point (REF) at a predetermined longitudinal detection position, - a belt skew (θ) of the belt (TP) depending on at least two determined lateral positions (y x (t1), y x (t2)), where the belt skew (θ) corresponds to an angle between a current belt movement direction (TMD) of the belt (TP) and the longitudinal direction (X), - a skew control signal (u ϑ ) depending on the determined belt skew (θ), - a head rotation position of the head (HU) depending on the skew control signal (u ϑ ) so that the head (HU) is aligned with the current tape movement direction (TMD) in such a way that the head (HU) is functionally capable of reading and / or writing data. [14] Device for operating a storage unit with at least one tilt element, a tape (TP) and a head (HU) which is functionally capable of reading data from or writing data to the tape (TP), the tape (TP) being movable in a predetermined longitudinal direction (X), the device being functionally capable of - at least two consecutive current lateral band positions (y x (t1), y x (t2)) of the strip (TP) with respect to a predetermined reference point (REF) at a predetermined longitudinal detection position, - a belt skew (θ) of the belt (TP) depending on at least two determined lateral positions (y x (t1), y x (t2)), where the belt skew (θ) corresponds to an angle between a current belt movement direction (TMD) of the belt (TP) and the longitudinal direction (X), - a skew control signal (u ϑ ) depending on the determined belt skew (θ), - the at least one inclination element depending on the skew control signal (u ϑ ) so that the tape movement direction (TMD) of the tape (TP) is aligned at the head (HU) in such a way that the head (HU) is functionally capable of reading and / or writing data.

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