Abstract: Holographic data storage media having a sandwiched construction are described in which a holographic recording material is sandwiched between two substrates. The substrates may be formed with fluid containment features in proximity to outer edges of the respective substrates. Also, the substrates may be formed with centerpieces that are recessed relative to the outer surfaces of the respective substrates. Such substrate features can improve and simplify the media fabrication process and may improve media quality.

Abstract: In one embodiment, the invention is directed to techniques for controlling the abrasivity of magnetic tape without modifying the coating formulas used to create the magnetic tape. For example, the invention may involve controlling or adjusting the abrasivity of magnetic tape using one or more burnishing techniques such as lapping, vaming or scraping. In this manner, the abrasivity of magnetic tape can be controlled or adjusted to ensure that the tape meets the necessary tape specifications without modifying the coating formulas applied during the coating process.

Abstract: The invention presents techniques for marking data storage media and responding to disturbances in the marking process. In one embodiment, the invention presents a system that uses a laser to emit a beam to ablate physical marks in a data storage medium. The system includes a sensor such as an optical sensor, configured to detect the position of the data storage medium and to generate a position signal as a function of the position of the data storage medium. An optical device, controlled by an actuator, directs the beam from the laser to an ablation site on the data storage medium as a function of the position signal.

Abstract: The diffraction-based monitoring techniques described herein can be used, for example, as quality assurance measure in manufacture of magnetic recording media with servo tracking. In one embodiment, the invention presents a system comprising a light source such as a laser that directs light upon a surface of a magnetic recording medium. The magnetic recording medium has two or more physical marks, and the light striking the magnetic recording medium produces a diffraction pattern. A light detector such as a photodiode detects some or all of the diffraction pattern. The physical marks may be servo tracks on the magnetic recording medium, and the detected diffraction pattern is a function of the characteristics of the servo tracks.

Abstract: Time-based servopositioning systems, methods, formats, and data recording media used in association with the same, employing bands of signals that differ from each other in the polarity of the servo signal, or the orientation of the servo signal, or the pattern width of the servo signal.

Abstract: The invention combines the benefits of sectored servo data with the benefits of time-based servo data. Recording media such as magnetic tape, magnetic disks, optical tape and optical disks can store servo data in a time-based sectored servo format.

Abstract: A carrier (20) is used in the thin film coating of disks (35). The disks (35) are held in a disk tray (30). The disks (35) have a center (35a) through which the thin film coating can go through. The carrier (20) includes a base plate (21) for receiving the disk tray (30). A plurality of discrete shields (24) are positioned in alignment with the center openings of the disk (35). The shields (24) are releasably connected to the base plate (21). Preferably, the shields (24) are releasably connected by a magnetic force.

Abstract: The invention is directed to self-referenced holographic recording techniques that make use of an element of a holographic medium to create a reference beam from a zero frequency Fourier component of a data encoded object beam. In other words, the self-referencing element may be formed on the holographic medium, rather then being a separate element of the holographic recording system. The element may comprise a diffusive element on the medium, designed to create a reference beam having controlled angles, phase and/or amplitude.

Abstract: In general, the invention is directed to techniques for reducing deformation of tape in data tape cartridges during storage to promote dimensional stability and increased tape longevity. The techniques involve controlling the winding tension applied to a tape during a final winding pass prior to unloading a data tape cartridge containing the tape from a drive. Excessive winding tensions can produce strain and compression on a tape pack, causing the tape to deform over time. Applications of reduced winding tension during the final pass provide reduced tape pack tension during periods in which the data tape cartridge is not used.

Abstract: The invention is directed to self-referenced holographic recording techniques that make use of a diffusive element. Self-referenced holography refers to holographic recording techniques in which a reference beam is created from a zero frequency Fourier component of a data encoded object beam. In accordance with the invention, a diffusive element can be positioned in a holographic recording system to create the reference beam from the zero frequency Fourier component of the data encoded object beam. Using a diffusive element to create a reference beam in self-referenced holography can provide advantages to the self-referenced holographic recording system.

Abstract: A system and method to minimize the contribution of head channel spacing to the negative effects of transverse changes in dimensions of recording media having prerecorded servopositioning tracks. Multiple channels on the recording head are separated into multiple groups of head channels, and each group of heads is independently positioned relative to the pre-written servo tracks. The head comprises an actuator for each pair of head groups. The actuator adjusts the relative spacing between members of the pair in response to position error signals indicating misalignment between the heads and the pre-written servopositioning tracks on the medium.

Abstract: A magnetic recording medium includes a highly permeable magnetic layer proximal to a recording layer. During recording, the permeable magnetic layer modifies the recording field from a recording head to produce consistently shaped recording transitions with a significant perpendicular component. The transitions are consistently shaped even though the distance between the recording head and the surface of the medium may change. Transitions so formed result in a reduction of noise from the medium surface roughness. The permeable magnetic layer further reduces noise caused by stray dipole fields.

Abstract: An optical disk exhibiting no detrimental thickness increase (edge wedge effect) that arises at the outer diameter of an optical disk substrate during an injection molding manufacturing process, and an apparatus and method for making such a disk. The optical disk of the present invention is designed for use with an optical disk player, especially where the data on the optical disk is stored air incident. This optical disk includes a disk substrate made from a molded polymeric material. The disk substrate has a first major surface, a second major surface, and an outer edge. The first major surface of the optical disk includes a data region having an intermediate portion and an outer portion. The outer portion extends to the outer edge of the optical disk. The disk substrate has a thickness defined by the distance between the first major surface and the second major surface. The optical disk also includes an information layer covering the data region.

Abstract: The present invention provides techniques for generating an intense magnetic pulse very quickly. The present invention includes a device that drives high current through a write head, which generates a burst of magnetic flux that in turn generates a high-intensity fringing field. To rapidly build up the current through the write head, the write head is coupled to a high voltage source. A switching circuit prevents current from flowing in the write head. In response to a signal from a control circuit, the switching circuit provides a path for current to flow through the write head. Current flow through the write head rises rapidly, which causes a burst of magnetic flux and generates a high-intensity magnetic fringing field. The high-intensity fringing field may be used to write to a magnetic medium.

Abstract: A surface treated magnetic pigment particle suitable for use with a binder in an information-recording layer of magnetic recording media. The surface treated magnetic pigment particle is a magnetic pigment particle with at least first and second surface treatment agents adsorbed onto the surface of the magnetic pigment particle. The first surface treatment agent has the formula E—X1—A1 wherein E is an electron withdrawing group which is not reactive with the binder, A1 is an acidic group, and X1 is a divalent moiety. The second surface treatment agent has the formula F—X2—A2 wherein F is a functional group reactive with the binder, A2 is an acidic group, and X2 is a divalent C1-4 alkyl moiety.

Abstract: A magnetic recording medium including a non-magnetic substrate and a magnetic coating. The non-magnetic substrate defines a front side and a backside. The magnetic coating is formed over the front side and is characterized by an Abrasivity Index of not greater than 350 microinches. In one preferred embodiment, the magnetic coating includes a lower layer formed on the front side of the substrate, and an upper layer formed over the lower layer. In this regard, the upper layer includes a magnetic metal particle dispersed in a binder and otherwise provides the Abrasivity Index. In another embodiment, the magnetic recording medium is a DLT tape.

Abstract: Magnetic patterned media comprise topographical features readable with a slider-mounted non-magnetic transducer sensitive primarily to a local aerodynamic boundary condition, in addition to a magnetic recording layer substantially conforming to the topographical features. Passage of a transducer over the features generates effects that can be detected in, and separated from, the magnetic recording signal.

Abstract: A method and apparatus for optical tracking in an edge-guided tape recorder is provided. In one embodiment, an optical tape guiding system for use in an optical tape drive which may write to optical tape is provided. The optical tape has a first edge and is disposed to be transported through the optical tape drive, and the optical tape exhibits transverse motion during transport through the optical tape drive. The system includes a curved edge guide disposed to maintain contact with the first edge of the optical tape during transport through the optical tape drive. The system may further include a mirror galvanometer disposed to direct a record beam of the optical tape system to the optical tape.

Abstract: A tape reel assembly for a data storage tape cartridge including a hub, and first and second flanges. The hub defines a hub axis and opposing first and second ends from which the flanges extend, respectively. The first flange includes a radially extending main body and an adjustment section. The adjustment section is provided within the main body, defines a tape edge contact surface, and is characterized by an increased flexibility as compared to the main body. The tape edge contact surface is readily deflectable relative to the hub axis. The adjustment section is configured such that a deflection orientation of the tape edge contact surface is a function of pressure on the hub. During use, as pressure on the hub increases (e.g., tape winding pressure), the adjustment section positions the tape edge contact surface to desirably direct the wound tape to a consistent lateral position.

Abstract: A system is described including a data tape cartridge carrying a non-tape storage medium, and a tape drive emulator that receives the data tape cartridge and stores data on the medium in a format that emulates a tape storage format. The tape drive emulator sequentially records the data within the logical storage areas of the non-tape storage medium, and maintains a library of tape marks on the storage medium to indicate locations within the stored data files. The library of tape marks may indicate, for example, file marks, sequential file marks, block marks, and other demarcations within the stored data. The tape drive emulator makes use of the library of tape marks to access the non-tape storage medium in response to tape access commands from a host computing devices.