Active spacing control for contactless tape recording

Abstract

The present invention relates to the field of tape drives, tape transports, tape heads, and tape head suspensions. More specifically, the present invention relates to magnetic tape data storage and tape recorders that include components designed to minimize or eliminate the contact of the head with the tape to reduce or eliminate wear and contamination of the tape drive head. The methods and apparatus of the present invention can dynamically control the head-to-medium spacing by moving the position of the head relative to the tape. Such apparatus can include components designed to minimize the magnetic spacing. This can be accomplished using actuators that move the head, move the tape, or move both the head and the tape simultaneously. This can include a back surface that supports the tape. Alternatively or additionally, mechanisms that contact and drive the back surface of the tape can be used to perform the movement of the tape past the head.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application 63 / 049,085, filed July 7, 2020, the disclosure of which is incorporated herein by reference.

[0003] Background of the invention Technical Field

[0004] This disclosure generally relates to recording computer data on a tape. More specifically, this disclosure relates to controlling the spacing between the recording head and the magnetic tape in a tape drive. Background Technology

[0005] For decades, magnetic tape has been used to store information. Initially, it was primarily developed and used to store audio information, such as vocals and music. Later, it was adapted to record computer data. Over the years, tape recording technology has continuously improved so that more and more information can be stored per unit area of ​​tape. After decades of development, many different types of recording heads and recording media have been developed. Even today, tape remains the most cost-effective way to archive computer data for the future. Companies are also legally obligated to store data for the future. Therefore, the demand for magnetic tape will continue for the foreseeable future to store data in archives.

[0006] Tape drive manufacturers constantly face the challenge of producing tape drives with greater storage capacity to meet market demands. One way to achieve this is by increasing storage density through improvements to the magnetic layer of the tape. By increasing storage density, for a given width, the tape can have more tracks, and each track can have more bits per unit length. Improvements to devices known as recording transducers, heads, or magnetic elements also contribute to increasing the number of bits of data that can be recorded per unit length and the number of data tracks per unit width of the tape.

[0007] A crucial factor affecting the accuracy of the read / write process is the magnetic pitch. The distance between the magnetic layer on the tape used for recording information and the transducers used for writing and reading data is called the magnetic pitch, or head-to-media spacing (HMS). Magnetic pitch is a critical parameter because the amplitude of the playback signal decreases exponentially with increasing magnetic pitch. The reduction in amplitude caused by increased magnetic pitch is known as Wallace pitch loss. Increasing the magnetic pitch increases the width of the readback pulse, resulting in lower data density. The quality of recorded or written information also varies with the pitch; a smaller magnetic pitch improves the quality of the write operation. A smaller magnetic pitch requires the read / write head to be closer to the main surface area of ​​the tape during operation.

[0008] The magnetic pitch of the driver is currently set in the factory and changes continuously during long-term operation. After a sufficiently long period, a steady-state magnetic pitch is formed. Currently, magnetic pitch is typically designed in the range of 20–50 nanometers (nm), depending on product requirements and materials. Generally, for a given read / write accuracy, a smaller magnetic pitch supports higher data density, while a larger magnetic pitch supports lower data density. If a system is designed to operate at high data density, but the magnetic pitch is too large, an unacceptable decrease in read / write accuracy will occur. Increased magnetic pitch also leads to increased error rates and reduced signal-to-noise ratio.

[0009] Today, read / write heads have a feature called "pole tips," and these tips typically wear down when the tape medium rubs against them. This wear is caused by friction or friction between the tape medium and the read / write head pole tips. This is commonly referred to as pole tip recession (PTR). PTR occurs over time, and this wear causes the pole tips to wear away and gradually move away from the tape. Over time, this process also leads to head wear. Therefore, PTR increases the magnetic spacing between the magnetic field in the tape's magnetic layer and the transducer in the head. Each transducer in a tape driver has a unique magnetic spacing. Furthermore, different transducers wear at different rates. Additionally, the position of the transducers can lead to different pole tip recession rates.

[0010] Since the invention of magnetic recording tape more than 60 years ago, the tape head has operated in full contact with the top of the tape, which includes magnetic material. In fact, in most tape transport systems, at least part of the magnetic head applies some pressure to the tape to keep it under precise tension. Because of this, head wear and tip deterioration have become part of the design of modern tape recording systems.

[0011] More complex tape head geometries create a pressure difference between the two sides of the tape as it flows over the head. In some cases, an air bearing is formed when the tape flows over a surface, preventing the tape from making "tight" or "frictional" contact with the head. Furthermore, modern heads use various coatings and / or multi-layer coatings to increase the distance between the tape recording surface and the head poles. As a result, the minimum distance between the tape and the head cannot be measured in nanometers.

[0012] One method that helps minimize the distance to the read / write head (i.e., the gap between the read / write head and the medium) involves using sharp edges to create a low pressure near the read / write head. The phenomenon of creating this low-pressure area near the read / write head is called scraping, and the sharp edges used to create this low pressure are called scraping (i.e., sharp) edges to scrape away (scrape away) air. As described above, these shaped edges create a low-pressure area directly behind the scraping edges as the belt moves past them. Because the air pressure is higher on the opposite (back surface) side of the belt, this low pressure pulls the belt into close contact with the head.

[0013] The advantage of this type of scraping solution is a small head-to-head pitch and stability over a wide range of belt speeds. The disadvantage is that the direct contact between the head and the belt increases friction and wear. To prevent excessive friction, the belt can be intentionally roughened (i.e., the belt surface has scattered bumps) so that only a small portion of the belt surface actually contacts the belt-bearing surface of the head. In effect, these bumps increase the head-to-head pitch.

[0014] Alternatively, to increase linear recording density, a reduction in the distance between the tape and the head can be sought by using a smoother tape. However, this leads to increased friction and / or an increased surface area of ​​the tape surface rubbing against the head. This friction or wear degrades the recording surface of the tape and the performance of the head, which in turn reduces the readback performance of the tape and tape driver. In extreme cases, friction can even cause the tape drive motor to stall and lead to tape breakage, which can occur when the head surface adheres to the tape surface—a phenomenon commonly referred to as "static friction."

[0015] Therefore, tape transport systems and tape head suspension systems that can minimize or eliminate contact between the tape and the read / write head while maintaining their operably close proximity are highly desirable, as they allow for closer head-to-medium spacing without degrading the performance of the tape or the read / write head.

[0016] For all the reasons mentioned above, tape drives are typically designed to accommodate tip decay and the resulting performance degradation. The need to design for tip decay results in a lower data storage density than could be supported if degradation could be prevented. By convention, tape drive designs must provide sufficient margin for variations in transducer wear rates and locations. This necessitates designing tape drives with theoretically lower data storage capacities. One reason is that tape read / write heads are typically manufactured with numerous coatings that increase the distance between the head and the medium. Therefore, tape drives can increase recording density by reducing the distance between the transducer tips and the tape. Larger storage capacities could also be achieved if a reliable and efficient method were found to eliminate or significantly reduce tip wear.

[0017] The applicant's invention, summarized below, solves these and other problems. Furthermore, to maximize the amount of data stored on the tape and improve reliability, a method is needed to reduce the distance between the tape driver's head and the medium, while minimizing the contact between them. Summary of the Invention

[0018] The currently claimed invention relates to means, methods, and non-transient computer-readable storage media for controlling the head-to-medium spacing in a tape driver in a novel manner. In one embodiment, an means includes a group of magnetic elements (e.g., one or more tape driver read or write heads), a sensor for sensing head-to-medium spacing (HMS) data, a tape guide that contacts the rear surface of the tape, and an actuator that moves the magnetic element when the HMS associated with the magnetic element is controlled to a desired distance. The means also includes a controller that controls the movement of the actuator as the tape moves past the group of magnetic elements to adjust the HMS to correspond to the desired distance.

[0019] In another embodiment, the method of the present invention receives sensor data from a sensor via a controller that monitors the head medium spacing (HMS) associated with the tape and the magnetic element assembly. Here, the controller can evaluate the data received from the sensor, identify the HMS based on this evaluation, determine that the HMS should be adjusted to correspond to a desired distance, and control the movement of an actuator as the tape moves past the magnetic element assembly to adjust the HMS to correspond to the desired distance.

[0020] In yet another embodiment, the method of the present invention can be implemented on a non-transient computer-readable storage medium. Here, the processor can execute program instructions to control the magnetic spacing. In executing these instructions, the processor can receive sensor data from a sensor, perform an evaluation of the data received from the sensor, identify the HMS based on the evaluation, identify that the HMS should be adjusted to correspond to a desired distance, and control the movement of the HMS to adjust the HMS to correspond to the desired distance as the strip moves past the magnetic element group. Attached Figure Description

[0021] Figure 1 A belt driver is shown for a magnetic head that includes an actuator to control the head-to-medium pitch (HMS) to a previously impossible degree.

[0022] Figure 2 It shows Figure 1 Close-up view of several components shown.

[0023] Figure 3 It shows the relationship with Figure 2 The components shown are similar to several other components.

[0024] Figure 4A cross-sectional view is shown, including the portion at or near the surface of the tape when data on the tape is read or written.

[0025] Figure 5 An embodiment of the present disclosure is shown, which includes the feature of changing the relative pressure of the air near the surface of the belt.

[0026] Figure 6 A series of components, including magnetic readout elements, sensor elements, and writer elements, are shown.

[0027] Figure 7 This illustrates a series of steps that can be performed during the head-to-medium spacing calibration process and when controlling the movement of the head when reading data from or writing data to the tape.

[0028] Figure 8 Electronic components are shown that can be used to communicate with or control the operation of a belt driver. Detailed Implementation

[0029] This invention relates to the fields of tape drivers, tape transmitters, tape heads, and tape head suspensions. More specifically, this invention relates to magnetic tape data storage and tape recorders, including components designed to minimize or eliminate head-to-tape contact to reduce or eliminate wear and contamination of the tape driver head. The methods and apparatus of this invention can dynamically control the head-to-medium spacing by moving the position of the head relative to the tape. Devices conforming to this disclosure include components designed to minimize magnetic spacing. This can be achieved using actuators that move the head, move the tape, or move both the head and the tape. This may include supporting the rear surface of the tape. Alternatively or additionally, the movement of the tape over the head can be performed using a mechanism that contacts and drives the rear surface of the tape. For example, the rear surface of the tape may contact a rotating roller, which, when rotating, can force the tape forward or backward as data is read and / or written to the top of the tape. By reducing or eliminating contact between the head and the tape, tape roughness and head coating thickness can be reduced, resulting in a smaller head-to-medium spacing and higher air density. In some cases, based on the reduction or elimination of head / medium contact, specific coatings included on the surface of a conventional head can be removed.

[0030] To achieve the high areal density writing and reading used in modern tape systems, the magnetic tape must be very close to the magnetic read / write elements on the tape read / write head. Research efforts have focused on finding a feasible solution to reduce the distance between the magnetic recording layer of the tape and the read / write elements of the head. This is commonly referred to as the magnetic pitch or head-to-medium spacing (HMS). Since reducing this pitch increases linear recording density (LD, typically measured in kilobits per inch), reducing the HMS increases the recording density. In fact, the LD of tape read / write systems is very sensitive to the magnetic pitch. In the relevant field of hard disk drives, it is a well-known fact that areal density capacity (ADC, measured in kilobits per square inch) is the product of linear density and track density (in kilotracks per square inch), and is inversely proportional to the square of the HMS. Therefore, for example, halving the HMS may quadruple the ADC. Magnetic elements commonly used in tape recording today include modern forms of magnetoresistive (MR) heads, often called tunneling magnetoresistive (TMR) heads. The heads typically also include sensing elements capable of generating strong and rapidly changing magnetic fields. Various forms of MR heads, including TMR heads, include transducers that improve sensitivity by magnetically biasing the read element in the tape head. Any of the various inductive or magnetoresistive elements included in a tape write head or read head means that any of these heads is essentially a "magnetic element" because they are sensitive to, respond to, receive, or generate electromagnetic fields.

[0031] Current tape systems have a magnetic pitch of tens of nanometers. This pitch increases over time as the tape driver operates, due to deposits on the head and varying wear of the read / write elements relative to the rest of the tape-bearing surface of the head. These deposits may consist of media scraped off from the tape itself. They may also include contaminants that enter the tape driver and subsequently deposit on the head by falling onto the tape or head surface, and then being abraded onto the head surface by friction associated with the tape rubbing against the head.

[0032] In traditional tape drives, much of the spacing consists of the head and the coating on the tape. These coatings are essential to protect the head's read / write elements from tape wear. The art and science of magnetic tape recording systems lies in finding combinations of materials with appropriate abrasion resistance to achieve a reasonable head lifespan. To further protect the head's read / write elements, these elements are typically positioned away from tape recesses to prevent them from protruding into the tape. These recessed elements further contribute to increasing the head-to-medium spacing (HMS).

[0033] Therefore, if the tape driver can eliminate or significantly reduce the contact between the tape and the read / write head, then the coating on the read / write head, the recesses of the reader and writer, and the roughness of the tape can all be significantly reduced, thus significantly reducing the contribution to HMS. This reduction in coating, minus the necessary air gap, will lead to a significant reduction in HMS and a significant increase in LD and ADC. Due to the smaller pitch, an increase in LD of 50% or more is easily achievable.

[0034] Another way to increase surface recording density by eliminating head-to-strip contact is to allow for higher track density. Track density refers to the number of parallel data tracks that can be recorded on a single strip. Higher track density naturally requires narrower tracks and imposes a stricter track-following capability on the head suspension. In fact, as the strip flows past the head, there is considerable lateral movement (movement along the strip width). This lateral strip movement (LTM) is caused by misalignment and vibration in the strip transport mechanism, but also by friction between the head and the strip. This friction directly leads to linear strip compression (compression along the strip length), which is due to the discontinuity of strip tension at the point of contact between the strip and the head scraper edge. This linear strip compression causes compression waves to propagate along the strip at the speed of sound and reflect off the strip rollers. Resonant modes are thus generated and cause high-frequency linear strip compression to couple with lower-frequency LTM from the strip transport. This frequency combination makes it difficult for the head suspension to track the tracks, thus requiring wider tracks and limiting track density.

[0035] Eliminating contact between the tape and the head will eliminate the main source of high-frequency linear tape compression (i.e., contact with the scraping edge), thereby reducing the high-frequency components of the LTM, making tracking easier and allowing for narrower tracks, higher track density, and higher tape storage capacity.

[0036] Many other advantages stem from limiting or eliminating contact and friction between the head and the tape. Head wear and head contamination are the primary consequences of this contact and friction between the head and the tape. Head contamination currently requires periodic use of a "tape cleaner" to remove deposits from the head. After only a few thousand hours of operation, head wear eventually leads to head failure. The tape itself is also affected by friction with the head, resulting in a limited lifespan and the occasional catastrophic tape breakage event.

[0037] Historically, all these drawbacks of tape recording (head wear, head cleaning, and tape breakage) were considered unique to the technology and had become a "living fact" in tape data storage practices. The invention of non-contact tape recording systems aimed to change all of that.

[0038] As described above, the apparatus and method according to the invention can apply force to the rear surface of the belt while the magnetic head is carefully positioned above the belt in a manner that mitigates or prevents contact. These rear surfaces typically do not include a magnetic coating and may include rough surfaces, patterned surfaces, pitted surfaces, or rollers or mechanical components that move the rear surface of the belt. Furthermore, the surfaces behind the belt and the surfaces of the drive mechanism can engage in a manner that prevents slippage, similar to the manner of holes or recesses in a gear meshing chain.

[0039] Pressure gradients obtained through various means can also be used to maintain the relative position between the back surface of the belt and the mechanical drive mechanism. These pressure gradients can be generated through unique forms of scraping design, pressurized gas, or vacuum pressure. These pressure gradients can push, pull, or simultaneously push and pull the belt to the desired position. Passivated edges or patterned surfaces can also help maintain the relative position of the belt with respect to other features of the belt driver, or prevent scraping action from forming where it is not needed.

[0040] Figure 1 A driver is shown, which is suitable for including a magnetic head coupled to an actuator to control the head-to-medium pitch (HMS) to a previously impossible degree. Figure 1 The magnetic head with driver 100 can be controlled to reduce or eliminate physical contact between the magnetic head and magnetic tape 110. Figure 1The device includes a magnetic tape 110, tape reels 120A / 120B, guide rollers (130A, 130B, 140A, and 140B), a head roller 150, and a head carrier assembly 160. Tape reels 120A and 120B allow the tape to be wound in layers around each reel, much like a conventional tape driver. Each of these reels can be coupled to a corresponding motor that allows the tape 110 to be pulled, pushed, or unpulled from its respective reel. As in a conventional tape driver, data can be written as the tape 110 moves through the tape driver's head in different directions (right-to-left or left-to-right). Tape reels 120A / 120B also help maintain tension in the tape 110. Tape reels 120A / 120B can maintain tape tension by acting as a motor driver, for example, via a direct current (DC) brushless motor. Brushless DC motors are widely used in various forms of data storage devices, such as spindles with drivers and media stacks for disk drives. Those skilled in the art will understand that a brushless DC motor comprises coils adjacent to magnets, which are coupled to a rotating spindle. The spindle is forced to rotate based on various different coils energized in a series of pulses that generate magnetic fields, which in turn interact with the magnetic field of the rotor magnets. Here, the interaction of the magnetic fields (the magnetic field generated by these electrical pulses and the inherent magnetic field of the rotor permanent magnets) forces the spindle to rotate. Brushless DC motors use magnetic fields to generate motion without any physical contact between the stator wires and the magnets; therefore, brushless DC motors do not produce particles from the motion they generate, unlike brushed DC motors, which transmit power through brushes as they rub against a surface. While stepper motors are another form of motor that can be used with drivers to move magnetic tape, brushless DC motors are often preferred because they tend to rotate more smoothly and do not have the cogging effect associated with stepper motors.

[0041] Belt rollers 130A, 130B, 140A, and 140B assist in guiding the belt 110 as it moves, and these rollers also help maintain the tension of the belt 110. The belt head roller 150 can also be used to guide the belt 110 and can further guide the belt 110 (from...) by applying a rotational force to the rear surface of the belt 110 while maintaining belt tension. Figure 1The belt 110 can move in a right-to-left or left-to-right direction. The rear surface of the belt 110 or the edge surface of the belt head roller 150 may be patterned or include a roughened surface to help allow the belt head roller 150 to move the belt 110. The belt head roller 150 can be driven by any motor known in the art. For example, the motor coupled to the belt head roller 150 can be a DC brushless motor or a stepper motor. The relative positioning of the belt head roller 150, belt rollers 140A and 140B can be used to control the head wrap angle of the belt 110 around the belt head roller 150. This can help optimize the amount of physical contact between the belt 110 and the belt head roller 150. The positioning of the belt rollers 130A / 130B, 140A / 140B, and belt reels 120A / 120B can help optimize or control the tension of the belt 110. Any of the belt rollers 130A, 130B, 140A, or 140B may include an active or passive tensioning mechanism, wherein belt tension is controlled by a force applied to the belt 110. Exemplary wrap angles used include, but are not limited to, angles approaching 90 degrees. Typically, the belt rollers 130A, 130B, 140A, and 140B are free to rotate or allow the belt 110 to move with little or no friction.

[0042] While the head roller 150 can be coupled to a motor that can be used as the main drive for moving the belt 110, roller 150 can alternatively not be directly coupled to the motor. When roller 150 is not directly connected to the motor, the motor coupled to the belt reels 120A / 120B can move the belt 110 as in a conventional belt drive. In this case, the head roller can rotate freely or allow the belt 110 to move with little or no friction.

[0043] Although not in Figure 1 As shown, the head roller 150 can be coupled to one or more actuators (active or passive) that allow the roller 150 to move toward or away from (in the direction of movement). Figure 1 The magnetic head of the belt driver 100 moves in the vertical direction. An actuator that moves the belt head roller 150 can provide relatively large or coarse motion, thereby allowing new belt to be fed into the belt driver 100. This relatively large motion can include rotational motion or increasing the speed of the belt head roller 150 and... Figure 1 The linear movement of the gap between the magnetic heads above the belt 110. The actuator or actuation system of the moving roller 150 may include an actuator that provides relatively large (coarse) movement compared to a second actuator, the movement of which may allow the roller 150 to move with relatively small (fine) movements. Exemplary larger movements may be on the order of a few millimeters (about 1 / 10 inch) or a centimeter (about 1 / 2 inch), while exemplary smaller movements may be less than a nanometer, a few nanometers, or up to about a few hundred nanometers.

[0044] In some cases, the lead roller 150 can be coupled or interlocked with the head carrier assembly 160. This coupling mechanism allows the lead roller 150 to be within a given tolerance or threshold distance from the head surface or relative to other elements of the head carrier assembly 160 when in the operating position. Once the lead roller 150 is locked in the operating position, the HMS can be adjusted within the movement capability of the fine positioning actuator. For example, if the lead roller positions the belt within 1000 nanometers of the head surface, the actuator coupled to the head can have a stroke of at least 1000 or 2000 nanometers. The actuator can then be used to control the head-to-medium spacing of 1 nanometer or less.

[0045] Figure 2 The diagram shows Figure 1 Close-up view of several components shown. Figure 2 It includes a belt 210, a belt head roller 220, and a magnetic head carrier assembly 230. Figure 2 Roller 220 can be with Figure 1 The same type of roller as the 150-head roller. Figure 2 The head carrier assembly 230 includes a head carrier 240, an actuator 250, and a head assembly 260. The head carrier 240 itself may include the actuator 250 and the head assembly 260. Furthermore, the head carrier assembly 230 or the head carrier 240 may also include an actuation device (passive or active) that generally adjusts the position of the head carrier 240. The actuator 250 can be used for fine control of the position of the head assembly 260. (See also: Regarding...) Figure 1 The discussion focuses on exemplary coarse (or large) movements and fine (or small) actions. Larger movements might correspond to orders of magnitude of a few millimeters (about 1 / 10 of an inch) or a centimeter (about 1 / 2 of an inch), while smaller movements might correspond to movements from less than a nanometer to several hundred nanometers or more. Exemplary fine positioning actuators include piezoelectric actuators and thermal actuators. In some cases, piezoelectric actuators can be used for very fine position adjustments, while thermal actuators can be used for medium-fine position adjustments, and vice versa. The movement of the actuators can be controlled by applying a voltage to the actuators, and the movement of these actuators can be controlled at frequencies, for example, in the range of 30 Hz to 10 kHz, to maintain the desired HMS.

[0046] Such as about Figure 1 The lead roller 150 discussed here, the lead roller 220 may be motor driven or may be coupled to an actuator or actuation device that provides coarse (or larger) motion and fine (or smaller) motion of the lead roller 220.

[0047] Figure 3 The diagram illustrates the relationship between... Figure 2 The components shown in the diagram are similar to several other components. Figure 3This includes a belt 310, a belt head roller 320, a head carrier assembly 330, a head carrier 340, a head actuator 350, and a head assembly 360. However, three different head assemblies 360 are shown here, each including a corresponding head actuator 350. Note that if in Figure 3 A line is drawn between the different head assemblies 360, and this line will have a concave shape very similar to the concave shape of line 330C of the head carrier assembly 330. This relative positioning of the head assemblies 360 means that each of the different assemblies can have a similar HMS relative to the belt 310C for a given actuation stroke distance. Therefore, as the belt moves around the belt head roller 320, Figure 3 The nominal position of each of the three different head assemblies is approximately the same as the distance from the band 310. Here, the exemplary fine positioning actuator includes a piezoelectric actuator and / or a thermal actuator.

[0048] The edge surface of the belt roller 320 along which the belt 310 moves may have a convex shape. This also applies to... Figure 1 150 or head roller Figure 2 The edge surface of the head roller 220. Figure 3 It also includes a cross-sectional side view (320 side view) of the head roller 320. This side view includes the mounting hole 320H and the convex outer surface 320CV of the head roller 320. Figure 3 Each head assembly 360 or Figure 2 Each head assembly 260 can also be coupled to an actuator that moves these head assemblies in a direction perpendicular to the strip 310 or 210 (across the width of the strip), such as... Figure 3 The double arrow line X is shown. Therefore, the fine actuator included in the belt drive, consistent with this disclosure, can enable the head assembly to move in a first direction (towards and away from the belt surface) and in a second direction (along the cross-section of the belt head roller), i.e., perpendicular to the first direction. The hole 320H can be used to mount the belt head roller 320 to a shaft or a set of bearings.

[0049] An exemplary radius of the belt head roller 320 can be from approximately 10 mm to approximately 13 mm. This radius can be selected to adjust the rotational speed (RPM) of the belt head roller. Lower RPM values ​​may produce lower frequency disturbances to the belt, but may correspond to higher inertia, thus slowing down the start and stop speeds of the belt movement. Figure 3 The curvature of the protrusion 320CV on the roller 320 appears large, but it could also be very small, for example, only a few micrometers. This slightly raised surface may counteract the effect of the concave positioning of the head assembly mounted above or near the roller 320. This may allow the read and write elements of the head assembly to maintain better relative positioning.

[0050] Head positioning in the tape driver and interference compensation in the tape driver involve performing various measurements. Sensors can be used to transmit the distance between the head / head assembly and the tape. Sensors associated with measuring the head-to-medium pitch (HMS) include, but are not limited to, capacitive sensors, laser sensors, or laser diode sensors. The HMS value can also be inferred from the strength of the readback signal calibrated according to the Wallace pitch loss equation.

[0051] Without directly measuring HMS, it can be measured indirectly using a combination of sensors. This process may involve performing more than one measurement and subtraction. For example, a first sensor can be used to measure the thickness of the tape as it moves along a tape guide, and a second sensor can be used to measure the distance from the head to the tape guide. The HMS can then be calculated by subtracting the tape thickness from the distance between the head and the tape guide. The sensor measuring the distance between the head and the tape guide can also be a capacitive sensor or another type of sensor. The sensor measuring the tape thickness can also be a capacitive sensor comprising multiple plates spaced at a fixed distance. The first plate of this capacitive sensor can be placed on the top surface of the tape, and the second plate can be placed on the bottom surface of the tape. Any change in the sensor capacitance can be attributed to a change in the tape thickness between the capacitor plates.

[0052] Once the distance (Dl) between the belt-facing surface and the roller or belt guide, and the belt thickness (TH), are determined, HMS can be calculated almost instantaneously using the formula HMS = Dl - TH as the belt moves. HMS can then be adjusted to account for variations in belt thickness.

[0053] While controlling the HMS, the read element can be used to sense servo data, which is typically written adjacent to or embedded in the data tracks on the tape. This servo data can be used to precisely position the read and / or write heads on specific data tracks. Digital filtering techniques can be used to help filter out resonances associated with the mechanical components of the tape driver, or to help filter out the effects of tape vibrations or resonances related to the tape itself.

[0054] Figure 4 A cross-sectional view is shown, including the portion at or near the surface of the tape when data on the tape is read or written. Figure 4This includes a belt suspension or belt head roller 460 supporting the rear surface of the belt 470. Item 450 is the head-to-medium spacing distance between the surface of the belt 470 and the "belt-facing surface" 455 of the head or belt head suspension. The term "belt-facing surface" refers to a surface commonly referred to as the "belt-bearing surface" because this surface typically bears the frictional forces of belt movement. The term "belt-facing surface" is used herein because methods and apparatus consistent with this disclosure avoid bringing the belt into contact with such a surface. While this term may be used, it can be used interchangeably with the older term "belt-bearing surface" because this "belt-facing surface" may sometimes come into contact with the belt, for example, during calibration. In other cases, even with precise HMS control, the "belt-facing surface" may occasionally come into contact with the belt accidentally or unintentionally, for example, when the belt speed or direction changes.

[0055] Figure 4 It also includes a head carrier 410, a first-stage actuator 420, a second-stage actuator 430, and a head or sensor 440. In some cases, the first-stage actuator 420 may be a piezoelectric actuator, and the second-stage actuator 430 may be a piezoelectric actuator or a thermal actuator. The head or sensor 440 may be a magnetic read head element, a magnetic write head element, or a sensor (e.g., a capacitive / other) for measuring distance. The first-stage actuator 420 may act on the entire head strip including multiple heads, and the second-stage actuator 430 may act on a subset of adjacent heads (e.g., one, two, or some other number of heads).

[0056] Items 480 and 490 are part of a structure that can interlock the suspension / roller 460 to the head carrier 410 with a driver. Figure 4 The items included herein, along with other appendices to this disclosure Figure 1 This is not intended to be drawn to scale.

[0057] Figure 5 An embodiment of the present disclosure is shown, which includes the feature of changing the relative pressure of the air near the surface of the belt. Figure 5 It includes a head carrier assembly 510, an actuator A1, a head assembly 520, a read / write or sensing element 530, and an air channel 540 positioned facing the magnetic surface of the band 550. Figure 5 It also includes a guide 580, an actuator A2, and a block 570 located on or near the rear surface of the belt 550. The rear surface of the belt 550 is a surface that does not record data and may not contain any magnetic medium.

[0058] Edge surfaces 570E on the edge of block 570 form a low-pressure region that tends to pull or attract the tape 550 to the contact block 570. These surfaces 570E can be referred to as scraping edges located on the rear surface of the tape 550 that generate low pressure at region 560. At point 560, low pressure is caused by the rear surface of the tape contacting or rubbing against block 570. For example, the angle generated by this low pressure at position 560 can be on the order of 1 to 5 degrees. The low pressure generated by the scraping edges 570E pulls the tape 550 away from the read / write element 530. This differs from conventional tape drives, which rely on the tape being dragged or pulled toward the surface of the read or write head.

[0059] Air passage 540 can be used to provide pressurized air or air at a higher temperature. Figure 5 The ambient air pressure at position 560 is the air pressure at the ambient air pressure. Therefore, Figure 5 The device can pull and push the belt 550 in a direction away from the element 530. Actuators A1 and A2 can then be used to control it. Figure 5 The HMS of component 530. Air channel 540 can be... Figure 5 The filter, not shown, is coupled to the external environment. Due to the scraping edge 570E and / or due to the air passage 540, the magnetic medium on the front (or recording) surface of the tape 550 may never come into contact when writing data to or reading data from the tape 550.

[0060] Figure 6 An assembly of a series of elements is shown, which may include magnetic readout elements, sensor elements, and writer elements. Figure 6 The element strip 610 includes a write element 620, a sensor element 630, and a read element 640. Note that each of these elements is shown in a different shape; the write element 620 includes two smaller rectangles located inside a larger rectangle, the sensor 630 includes a smaller circle located inside a larger circle, and the read element 640 is shown as a set of lines (or three rectangles of the same size stacked on top of each other) within a rectangle.

[0061] Note that when carrying Figure 6 As the upward arrow indicates the direction, each of the individual elements is positioned approximately at a location close to the surface of the belt facing the belt at a relative position. Note Figure 6 The portion marked with element strip 610, in which two write elements are separated by read elements—as indicated by the text WRW. Figure 6 It also identifies sensor elements (Sense), which include sensors adjacent to read elements, write elements, or both. Note that as the belt moves upward, each set of read / write elements can be used to write different data tracks and read back the data immediately after writing. These elements are also capable of reading track positioning data, which can be used to follow or write servo data on the belt. Figure 6 It is not drawn to scale.

[0062] The component strip includes a central read head strip and two distinct write head strips, on either side of the read head strip, such that when the strip is in the first direction (e.g., as shown in the image), the write head strip is positioned such that when the strip is in the first direction, the write head strip is positioned such that the write head strip is positioned such that when the write head strip is in the first direction, the write head strip is positioned such that ... Figure 6 Data written during upward movement (as shown) or when the strip moves in a second direction (e.g., downward) can be read and verified immediately after writing. Data from sensor 630 can be used to adjust the head media pitch, such as regarding... Figures 1-5 As discussed above, the actuator in the belt driver can also move across the width of the belt when the track follows or seeks a portion across the width W of the belt 650. Therefore, the element strip 610 can move from left to right when the track follows or seeks a portion across the width W of the belt 650.

[0063] Figure 7 This illustrates a series of steps that can be performed during the head-to-medium pitch calibration process and when controlling the movement of the head when reading data from or writing data to the tape. Figure 7 The process begins at determination step 705, which identifies whether head-to-medium (HMS) pitch calibration should be performed. If not, the program flow moves to step 740, where normal or nominal operating mode can be initiated. When determination step 705 identifies that HMS pitch calibration should be performed, the program flow can move to step 710, where the tape is positioned in an unused area and then moved at a low speed in step 715. Steps 720, 725, 730, and 735 are steps that can be repeated during the calibration process. These steps include receiving HMS sensor data (720), evaluating the HMS sensor data (725), and adjusting the HMS (730). Determination step 735 identifies whether the calibration process has been completed. This calibration process may include moving the head-carrying assembly toward the tape until the head-facing surface of the carrier assembly contacts the tape when the tape is moved at a low speed. Contact can be detected based on changes in belt tension, detected movement of the read element caused by friction, detected temperature rise of the read head due to friction with the belt, detected electrical contact between the read head and the belt, or other physical properties associated with the head-facing surface of the contact belt. Once a contact is detected, the read head carrier assembly can be removed from the belt simultaneously with receiving sensor data.

[0064] Although not in Figure 7As shown, however, the calibration process can include a coarse calibration and a subsequent fine-tuning calibration. Fine-tuning calibration may involve performing a series of read and write operations at slightly different heights above the strip. These reads and writes may occur as the strip moves under nominal conditions. Data collected during this fine-tuning process can identify the optimal HMS and can be used to identify how much the magnetic read / write performance changes with variations in instructions for a given HMS. Therefore, calibration can be adjusted based on optimal magnetic performance separated from absolute knowledge of the actual HMS.

[0065] When step 735 determines that calibration is incomplete, the program flow can return to step 720. As described above, steps 720, 725, 730, and 735 can be executed iteratively until the calibration process is complete. When calibration is complete, the program flow can move from step 735 to step 740, where normal or nominal operation with a driver can be initiated.

[0066] As long as the tape driver is operating in normal mode, the program flow can iteratively execute steps 745, 750, 755, 760, 765, and 770. Step 745 may receive HMS sensor data, step 750 may evaluate the received HMS sensor data, and step 755 may adjust the HMS. The received HMS sensor data can be evaluated to identify the current HMS spacing, thereby allowing control over tape thickness changes or a response to observed changes in flight altitude. As mentioned above, the HMS can be measured directly or calculated based on different measurements (e.g., the distance between the head-facing surface and the tape roller or tape guide minus a tape thickness measurement).

[0067] After step 755, track following (e.g., servo) data can be received in step 760, evaluated in step 765, and adjustments to the track following actuator can be made in step 770. After step 745, the program flow can return to step 745. Although in Figure 7 As not shown in the diagram, the program flow can end, allowing the tape to be removed from the tape driver.

[0068] Figure 7 The steps can be performed by any type of processor or multiprocessor known in the art. Such a processor can be dedicated to the task of moving the head carrier as described above. Alternatively, Figure 7 The steps can be performed by a processor that also performs other functions associated with the operation with the driver. In some cases, Figure 7 The program code can be implemented in low-level machine code or firmware. Certain steps or actions can be performed by any combination of electronic circuits or computer logic. Some functions can be performed using field-programmable gate arrays, application-specific integrated circuits, processors, or combinations thereof. Although Figure 7 A specific sequence of events is described, but embodiments of the invention can be performed by changing the order of these steps or by eliminating certain steps or separating them from the sequence of steps.

[0069] Figure 8 Electronic components that can be used to communicate with or control the operation of a belt driver are shown. Figure 8 The device 800 includes one or more processors 810, memory 820, read / write channel 830, input 840, output 850 and communication interface 860. Figure 8 The various components shown can be communicatively coupled to each other via bus 870. In operation, one or more processors 810 can execute instructions outside memory 820 to perform operations such as control band operations, control read and write operations, and control actuator movement as discussed herein. The one or more processors 810 can be any processor known in the art, but are typically microcontrollers that execute instructions from outside memory 820. Memory 820 can be any memory known in the art, and typically memory 820 will be or include random access memory (RAM). Memory 820 may also include non-volatile memory (e.g., flash memory) storing firmware code. Operation instructions stored in flash memory can be moved to RAM as part of the initialization process.

[0070] Read / write channel 830 may include a combination of analog and digital electronics, such as preamplifiers, analog filter electronics, digitization circuitry, and phase-locked loops / data splitters. Data read from and written to the tape will pass through the circuitry of read / write channel 830. Input 840 may be coupled to a sensor that senses the distance between the magnetic head and the medium, tape tension, tape speed, or other parameter data. Input 840 may also include or be coupled to an analog-to-digital converter that converts analog sensor data into digital data. In some cases, input 840 may receive digital data directly from the sensor.

[0071] Output 850 may include motor drive circuitry or actuator drive circuitry. Output 850 may control belt speed or may be used to drive actuators that affect the head-to-medium spacing, as discussed herein. Therefore, output 850 may be coupled to a DC brushless motor or to an actuator (e.g., a piezoelectric or thermal actuator). Communication interface 860 may be any form of communication interface known in the art. For example, the communication interface may be compatible with Small Computer System Interface (SCSI) or Serial Small Computer System Interface (SAS). Alternatively, communication interface 860 may be a network interface, such as an Ethernet interface. Figure 8 The device can receive commands and data from other computers and can provide data to the computer through the communication interface 820.

[0072] One or more processors 810 can control the operation of the belt driver based on commands received from other computers. One or more processors 810 can receive sensor data from input 840, control data transmitted via read / write channel 830, and can control the operation of a motor or actuator by sending signals via output 850. One or more processors can also cache data in memory 820 until the data can be written to the belt or provided to other computers.

[0073] While the various flowcharts provided and described above may show a particular sequence of operations performed by certain embodiments of the present invention, it should be understood that such a sequence is exemplary (e.g., alternative embodiments may perform operations in a different order, combine certain operations, overlap certain operations, or separate them from other operations, etc.).

Claims

1. A device for controlling magnetic pitch, the device comprising: A magnetic element assembly, the magnetic element assembly including a surface facing the strip; One or more sensors, the one or more sensors sensing data associated with the head-to-medium spacing between the front surface of the magnetic element group and the strip where the data is magnetically stored, wherein the head-to-medium spacing refers to HMS; A belt guide that contacts the rear surface of the belt, wherein the belt guide is cylindrical in shape, and wherein the belt guide and the magnetic element assembly are arranged facing each other. An actuator that moves the magnetic element group to control the HMS between the magnetic element group and the front surface of the strip, wherein the HMS is controlled by the movement of the actuator to correspond to a desired distance separating the front surface of the strip and the strip-facing surface of the magnetic element group; A controller, when data is transmitted between the magnetic element group and the front surface of the belt, receives sensor data from one or more sensors based on the movement of the belt past the magnetic element group, and controls the movement of the actuator to adjust the HMS to correspond to the desired distance.

2. The apparatus according to claim 1, wherein, The rear surface of the belt contacts the rotating belt guide, which forces the belt to move forward or backward as the belt guide rotates, when data is read and / or written to the top of the belt.

3. The apparatus according to claim 1 further includes a motor for rotating the guide.

4. A method for controlling magnetic spacing, the method comprising: The controller receives sensor data from one or more sensors, the controller monitoring the head-to-medium spacing associated with the tape and magnetic element group, wherein the head-to-medium spacing refers to HMS; The sensing data received from the sensor is evaluated; The controller identifies the HMS based on an evaluation of the sensed data; The HMS should be adjusted to correspond to the desired distance between the front surface of the strip and the strip-facing surface of the magnetic element group; and As data is transmitted between the magnetic element group and the front surface of the belt, the movement of the actuator is controlled based on sensor data received from the one or more sensors as the belt moves past the magnetic element group, to adjust the HMS to correspond to the desired distance. It includes a belt guide that contacts the rear surface of the belt. The belt guide is cylindrical in shape and is positioned opposite to the magnetic element group.

5. The method according to claim 4, further comprising: When the belt guide is a rolling element, the belt is moved based on the rotation of the rolling element.

6. The method according to claim 4, wherein, The rear surface of the belt contacts the rotating belt guide, which forces the belt to move forward or backward as the belt guide rotates, when data is read and / or written to the top of the belt.

7. The method of claim 4, further comprising writing data on the front side of the strip when the HMS is controlled to correspond to the desired distance.

8. The method of claim 4, further comprising reading data from the front of the strip when the HMS is controlled to correspond to the desired distance.

9. A non-transient computer-readable storage medium having thereon a program executable by a processor to implement a method for controlling magnetic pitch, the method comprising: The processor receives sensor data from one or more sensors, the processor monitoring the head-to-medium spacing associated with the strip and magnetic element group, wherein the head-to-medium spacing refers to HMS; The sensing data received from the sensor is evaluated; HMS is identified by the processor based on the evaluation of the sensed data; The HMS should be adjusted to correspond to the desired distance between the front surface of the strip and the strip-facing surface of the magnetic element group; and As data is transmitted between the magnetic element group and the front surface of the belt, based on sensor data received from the one or more sensors as the belt moves past the magnetic element group, the movement of the actuator is controlled to adjust the HMS to correspond to the desired distance. It includes a belt guide that contacts the rear surface of the belt. The belt guide is cylindrical in shape and is positioned opposite to the magnetic element group.

10. The non-transient computer-readable storage medium of claim 9, wherein the program is further executable to initiate at least one of writing or reading data on the front side of the strip when the HMS is controlled to correspond to the desired distance.

11. The non-transient computer-readable storage medium according to claim 9, wherein, The rear surface of the belt contacts the rotating belt guide, which forces the belt to move forward or backward as the belt guide rotates, when data is read and / or written to the top of the belt.

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