Abstract: A disk drive comprises a drive enclosure defining a generally rectangular form factor; an electromechanical assembly contained within the drive enclosure, and a printed circuit board assembly (PCBA) at least partially contained within the drive enclosure. The drive enclosure possesses at least one of the following characteristics: the drive enclosure defines chamfers on at least one of four corners of the generally rectangular form factor; and the drive enclosure defines a first surface and a second surface that defines an interior second surface portion and a peripheral second surface portion and wherein the interior second surface portion is further away from the first surface than is the peripheral second surface portion.

Abstract: According to one embodiment, a multilayer optical recording medium including a substrate, a guide layer group that is provided on the substrate and has guide layers in which positional information in a radial direction is recorded, and a recording layer group that is provided on the substrate and has recording layers in which information can be recorded. In the recording layer group, positional information of the recording layers associated with the positional information recorded in the guide layers and control information of the optical device where reflected light volumes of the laser beams on the guide layers and the recording layers become maximum at the positions in the radial direction are recorded at the positions in the radial direction of the recording layers.

Abstract: An optical information recording medium 10 comprises a plurality of recording layers 14 and intermediate layers 15 each provided between the recording layers 14. Each of the recording layers 14 includes a polymer binder and dye dispersed in the polymer binder, and a thickness of each recording layer is equal to or greater than 50 nm. A first interface (near-side interface 18) is formed between a recording layer 14 and an intermediate layer 15 that is adjacent to the recording layer 14 on one side of the recording layer 14 in a thickness direction of the recording layer 14, and a second interface (far-side interface 19) is formed between the recording layer 14 and an intermediate layer 15 that is adjacent to the recording layer 14 on the other side of the recording layer 14 in the thickness direction of the recording layer 14.

Abstract: An optical information recording medium includes: a recording layer 12 comprising a multi-photon absorption compound and a one-photon absorption compound; and a supporting member (base layer 11) configured to support the recording layer 12. In this optical information recording medium, absorption of multiple photons by the multi-photon absorption compound and absorption of one photon by the one-photon absorption compound cause a void to be generated in the recording layer, whereby information is recordable by modulation based on a presence or absence of a void.

Abstract: Disclosed herein is a multi-layer optical recording medium having n recording layers (n?3) in which recording and reproduction of information are carried out by laser light, the multi-layer optical recording medium including: a file system area configured to be disposed near a last logical address in an area used as a logical address space in which stream data is recorded, wherein in the other recording layers different from the recording layer in which the file system area near the last logical address is disposed, the logical address space is not allocated to an area overlapping with the file system area in a layer stacking direction.

Abstract: The present invention relates to a high data density optical recording medium. The invention further relates to an apparatus for reading from such an optical recording medium. The optical recording medium has marks that are arranged in tracks. The tracks have a cross section with a curved shape and protrude above a surface of the optical recording medium.

Abstract: An optical reading system is provided to improve read signal quality with increasing its linear recording density. An optical recording medium in which the distance from a light incident surface to an information recording layer is less than 100 ?m is irradiated with a laser beam through an objective lens and information stored in the information recording layer is read by means of a PRML detection method. At this time, the constraint length n in the PRML detection method is set to an integer which satisfies 0.5×(?/NA)/(LV/f)?1<n<0.5×(?/NA)/(LV/f)+1, wherein ? represents the wavelength of the laser beam, NA represents the numerical aperture of the objective lens, LV represents the linear velocity of the optical recording medium when recording, and f represents a channel bit frequency when recording.

Abstract: An optical recording and reading method is provided in which the information necessary for recording and reading layers is quickly acquired to reduce the seek time during reading and recording. The optical recording and reading method is used for an optical recording medium that includes a plurality of recording and reading layers and a servo layer. Information is recorded on or read from the recording and reading layers by irradiating them with a recording and reading beam while the servo layer is irradiated with a servo beam to perform tracking control. When information is recorded on the recording and reading layers, control information necessary for subsequent recording and reading to be performed on the recording and reading layers is recorded on the servo layer 18. When the subsequent recording or reading is performed, the control information on the servo layer is consulted, and then the recording or reading is performed on the recording and reading layers.

Abstract: Recordable DVD+R and DVD+R/W optical discs with two (or more) information layers are developed to double the data storage capacity and video recording time. A method and device are proposed to make dual layer DVD disc recordings compliant with the dual layer DVD-ROM standard Recording the data in a DVD-ROM compliant way on the dual layer DVD+R or DVD+R/W disc is obtained by shifting the middle zone area towards the inner radius of a disc in such a way that the data zones of both layers are filled up with data.

Abstract: An information medium substrate is formed as a flat plate and includes a first convex part formed on one surface of the information medium substrate in a region between a rim part of a center hole and an inner circumferential edge of an information region and a second convex part formed on another surface of the information medium substrate at a position that overlaps a protruding end part of the first convex part in a thickness direction of the information medium substrate.

Abstract: The present invention provides a method of recording identification information in an optical disc, by which specified disc identification information can be uniformly applicable to efficiently cope with the recording/reproducing of the optical disc. The present invention includes the step of recording disc identification information in a management area of the optical disc wherein the disc identification information identifies a disc type identified according to a disc thickness.

Abstract: An optical disk includes a plurality of disk sheets which are laminated, and each of which has a recording face on one of the surfaces and a flat back surface, wherein the plurality of disk sheets are laminated by adhesive layers in such a manner that between adjacent two disk sheets, a back surface of one of the disk sheets, on the opposite side of the surface where the recording face is formed, faces the disk surface of the other disk sheet. The foregoing structure realizes an optical disk of desirable recording/reproducing characteristics, which is flat and has a fixed interval between recording faces, and which permits the problems of coma aberration, spherical aberration, etc., to be suppressed.

Abstract: A high-density recording medium including a first surface and a second surface, the second surface being a light incident surface at a normal mounting condition, a clamping area, an information area including a recording layer provided adjacent to the second surface, a transition area extending between the clamping area and the information area, the transition area being defined from an end position of the clamping area to a beginning of the information area, and a slope being formed in the transition area on the first surface. Further, the slope is formed from the end position of the clamping area to a position placed at least a predetermined distance ahead of the start position of the information area, and a gap as a non-slanted area extends between the information area and a closer end of the slope thereto.

Abstract: An information storage medium with an array of laterally magnetised dots, as well as a process for producing this medium is disclosed. Each dot (2) contains at least one magnetic domain formed by a thin layer (4) of at least a magnetic material laterally covering this flat material and deposited at oblique incidence relative to the normal (z) to the plane (6) of the array. The invention applies in particular to computer hard drives.

Abstract: A high-density recording medium, and a recording and/or reproducing device are provided. At a transition area of the high-density recording medium allocated between a clamping area and an information area of the high-density recording medium is formed a step having a prescribed slope so that the high-density recording medium does not collide with an objective lens of an optical pickup provided in an optical disc device although the objective lens of the optical pickup is upwardly moved toward a recording layer of the high-density recording medium.

Abstract: The present invention relates to a high-density disk that is structured to prevent a collision of an optical pickup's objective lens with the high-density disk if the disk is placed upside down in a disk device that is able to record and reproduce signals to/from the high-density disk. A high-density disk recording medium according to the present invention is structured such that, wherein a recording layer having high-density pit patterns is offset from a center plane of disk thickness, both sides of a clamping zone bisected by the center plane have differing thicknesses. One or both sides may protrude from surface of the disk recording medium, or one side of the clamping zone may protrude from the surface while the other side is indented below the surface.

Abstract: In an optical information reproducing method for reproducing information from an optical information recording medium of land/groove and low-to-high recording system having a substrate (1) and a recording layer (2), light having a wavelength of 390 to 440 nm is projected to the recording layer (2) through the substrate (1) with use of an objective lens having a numerical aperture of 0.65 to thereby reproduce the information, wherein assuming that a wavelength of the light is ? and an index of refraction of the substrate (1) in the wavelength ? is ns, a depth D of a portion (G?) of the recording layer (2) corresponding to the groove (G) with respect to a portion (L?) of the recording layer (2) corresponding to the land (L) satisfies a relation of ?/5.8 ns?D??/5 ns.

Abstract: Preventing a molded disc substrate from generating a separation pattern. To this end, a molding die 1 includes a pair of stationary die 6 and movable die 7, and an outer circumference ring 16 for molding an outer circumference end of the disc substrate 2. The outer circumference ring 16 is so mounted as to be movable along forward and backward directions in parallel with a moving direction of the movable die 7 toward the stationary die 6, and has a retaining surface 39 for retaining the outer circumference of the molded disc substrate 2.

Abstract: An optical disk consists of a first laminated layer structure and a second laminated layer structure. The first structure has a first transparent substrate having a first surface and a second surface on both sides thereof, provided on the first surface being a light-incident plane via which a light beam is to be incident in recording or reproduction, formed alternately on the second surface being a plurality of first lands and first grooves, and a first organic-dye recording layer formed on the second surface to cover the first lands and grooves. The second structure has a second substrate, alternately formed on which are a plurality of second lands and second grooves, a reflective film formed on the second transparent substrate to cover the second lands and grooves, and a second organic-dye recording layer formed on the reflective film to face the second transparent substrate.

Abstract: In a master carrier for magnetic transfer which comprises a support that has a transfer-recording pattern arrayed in the track direction thereof in accordance with the information to be transferred to a magnetic recording medium, and a magnetic layer formed on the transfer-recording pattern of the support, the in-plane distance L (mm) between the hill and the valley of the warped master carrier, the vertical-direction distance H (?m) between the two, and the thickness d (mm) of the master carrier are so defined that they satisfy a relation of 0.05?H·d3/L?0.6.

Abstract: A recording layer (2) and a light-transmitting layer (3) are provided on a substrate (1) having a guide groove for tracking a light beam projected in a spot for information recording/reproduction. The spot light beam is projected onto the recording layer (2) through the light-transmitting layer (3) so as to record information in a first portion (G?) of the recording layer corresponding to the inside (G) of the guide groove and a second portion (L?) of the recording layer corresponding to a flat portion (L) between adjacent guide grooves. The depth d of the first portion (G?) with respect to the second portion (L?) on the light-transmitting layer side of the recording layer (2) satisfies the relation ?/5.8nf?d??/5nf where ? is the wavelength of the light and nf is the index of refraction of the light-transmitting layer (3) to the wavelength ?. The reflectance of the recording layer (2) after the recording is larger than that before the recording.

Abstract: In an optical disc in which an information signal is recorded/reproduced by irradiating a laser beam to a disc substrate 1 in which an information signal portion 1c has been provided on one principal plane from the side where the information signal portion 1c exists, a clamp reference surface 3a is set to the information signal portion 1c side of a replica substrate 1a constructing the optical disc. The clamp reference surface 3a is set to a flat surface and a thickness of the replica substrate 1a in a clamping area 3 is set to be larger than that of the convex-shaped replica substrate 1a in an information recording area 4. The replica substrate 1a in which a periphery of a center hole 1b is thicker than the information recording area 4 is used.

Abstract: A method of manufacturing an optical storage medium is provided, which comprises at least a transparent spacer layer (22) or transparent cover layer. This layer is provided by spincoating a liquid layer (22) between an inner radius ri and outer radius ro and substantial solidification by means of exposure to e.g. UV-radiation. The solidification of the liquid (22) is started at ri at a moment in time defined as t=ti. The solidification of the liquid (22) at ro takes place at a moment in time defined as t=to and to=ti+d and d>1 s. The solidification of the liquid (22) between ri and ro takes place at a moment in time between ti and to. The advantage is that the radial thickness uniformity of the solidified liquid (22) is substantially improved and better than +/??m.

Abstract: In a master carrier for magnetic transfer which comprises a support that has a transfer-recording pattern arrayed in the track direction thereof in accordance with the information to be transferred to a magnetic recording medium, and a magnetic layer formed on the transfer-recording pattern of the support, the in-plane distance L (mm) between the hill and the valley of the warped master carrier, the vertical-direction distance H (?m) between the two, and the thickness d (mm) of the master carrier are so defined that they satisfy a relation of 0.05?H·d3/L?0.6.

Abstract: The present invention relates to a high-density disk that is structured to prevent a collision of an optical pickup's objective lens with the high-density disk if the disk is placed upside down in a disk device that is able to record and reproduce signals to/from the high-density disk. A high-density disk recording medium according to the present invention is structured such that, wherein a recording layer having high-density pit patterns is offset from a center plane of disk thickness, both sides of a clamping zone bisected by the center plane have differing thicknesses. One or both sides may protrude from surface of the disk recording medium, or one side of the clamping zone may protrude from the surface while the other side is indented below the surface.

Abstract: An optical disk for a mobile device is provided. The optical disk includes a substrate, having an outer diameter less than 120 mm and not smaller than 30 mm and a thickness less than 1.1 mm and not smaller than 0.40 mm, so that a deflection angle of 0.7° or smaller can be obtained. Alternatively, the optical disk includes a substrate, having an outer diameter not smaller than 30 mm and a thickness not smaller than 0.435 mm, so that a deflection angle of 0.6° or smaller is obtained.

Abstract: A system and method for replicating magnetic patterns on hard disk media includes a mask located over or above a magnetic recording layer. The recording layer may include a single, dual, or multi-layer recording layer. A pattern is or has been formed in the mask, where the pattern defines the recordable regions and the non-recordable regions to be created in one or more layers within the recording layer. Portions of the recording layer are then exposed. An etch may then be performed to create grooves within one or more layers in the exposed regions of the recording layer. The magnetic properties of at least one layer in the exposed portions of the recording layer are then altered in order to create recordable or non-recordable regions. The mask is then removed from the recording layer.

Abstract: An optical recording medium with a circular body including a substrate, a recording layer and a dielectric layer on the substrate, the circular body having a recording/reproducing area and a hub attached to a surface of the circular body. When the circular body stands vertically, the recording/reproducing area of the hub-attached surface is curved in a convex form, and the flexural amount is from 5 ?m to 100 ?m.

Abstract: A piece of media, apparatus and method are provided wherein the piece of media may store the audio data as well as equalizer settings that permit the audio data to be equalized. In one embodiment, the piece of media stores equalized audio data and the equalizer settings. In accordance with the invention, in one embodiment, the equalizer-effect piece of media permits the audio data on the piece of media to be equalized even when the audio data player does not include an equalizer. In another embodiment, the equalizer-effect piece of media includes raw audio data and equalizer settings and permits an external equalizer to play equalized audio data without needing to set the equalizer. In a preferred embodiment, the piece of media may be compact disk.

Abstract: A disk-shaped optical data carrier having a first surface, a second surface, a CD information layer on which CD-standard data is stored, and a DVD information layer on which DVD-standard data is stored. A first reading light which captures the CD information layer enters the data carrier by the first surface. A second reading light which reads the DVD information layer enters the data carrier by the second surface. The DVD information layer is located approximately in the middle between the first and the second surface. A CD reading light which reads the CD information layer runs through the DVD information layer. The DVD reading light which reads the DVD information layer runs through the CD information layer.

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: An optical recording disk includes a support substrate, grooves and lands alternately formed on one major surface of the support substrate, an optical functioning layer formed on the one major surface of the support substrate on which the grooves and the lands are formed and including a recording layer and a light transmission layer formed on the optical functioning layer, the grooves and the lands being formed so that the depth Gd of each of the grooves is equal to or larger than 15 nm and equal to or smaller than 25 nm and the half width Gw is equal to or larger than 150 nm and is equal to or smaller than 230 nm, and the recording layer including a first recording film containing Si as a primary component and a second recording film containing Cu as a primary component.

Abstract: The magnetic recording medium includes: an underlayer constituted of at least a substrate and a nonmagnetic metal element; and an amorphous magnetic layer, made of amorphous magnetic material, which magnetically records information, wherein the amorphous magnetic layer has bumps on a surface thereof or the magnetic recording medium has bumps on a surface thereof (surface of a lubricating layer) so that density of the bumps is not less than 400 bumps/&mgr;m2 or so that height of the bumps is not less than 2% with respect to an average layer thickness of the amorphous magnetic layer. Thus, magnetic wall movement of the amorphous magnetic layer is effectively suppressed, so that it is possible to stably form a recording bit. Therefore, even in a case of performing high-density recording by forming a minute recording bit, it is possible to record information with sufficient signal quality.

Abstract: On a data recording region, an aluminum reflective film is formed together with a reflective film forming a pattern on an outer circumferential side of the data recording region. Although aluminum identical to the material of the reflective film on the data recording region can be employed for the reflective film on the outer circumferential region, gold, titanium and the like can also be used. Therefore, an optical disk that has a unique pattern formed at an outer circumferential region that was not conventionally used can be fabricated at a low cost.

Abstract: A system for recording data to a disc shaped record medium. The data is recorded according to a universal disc format employing a hierarchical file system, and data within the hierarchical structure is referenced using pointer information. The pointer information includes a file identifier descriptor and a file entry and is recorded such that the pointer information and its corresponding substantive data are stored at successive addresses.

Abstract: This invention is a technical inprovement of the CD & DVD medium. It involves the addition of a protective ring on the outside border of a CD & DVD to prevent the face of the CD & DVD containing the data from touching a surface where it may be placed on.

Abstract: Disclosed is an optical disk. The present invention includes a plate having a first area enabling to record information thereon and a second area unable to record the information thereon and a projection on the second area of the plate. Accordingly, the present invention enables to form a protecting layer having a uniform thickness thereon.

Abstract: This invention is an optical data recording medium having a substrate protective film for effectively suppressing deformation (warpage) associated with change in environmental humidity. The optical data recording medium includes a transparent substrate, a thin film layer formed on one surface of the transparent substrate, a thin film protective film formed of a resin as a main component on the thin film layer, and a substrate protective film formed of a resin as a main component on the other surface of the transparent substrate than the thin film protective film, in which the thin film layer is a single layer film or a multi-layer film including at least one of a dielectric film, a recording film and a reflective film, and the substrate protective film has a coefficient of humidity expansion that is larger than a coefficient of humidity expansion of the thin film protective film.

Abstract: An abrasion-resistant disc. The disc has a plurality of protrusions at the edge of the bottom surface. The protrusions prevent abrasion to the bottom surface of the disc.

Abstract: An optical disc for storage and retrieval of digital data, and a system and method for protecting the optical disc is disclosed. The optical disc has projections or embossments on one or both major surfaces. When the optical disc is placed on a substantially flat surface such as a tabletop or a desktop, the projections act as pedestals that elevate the optical disc above the flat surface. The resulting gap or clearance helps prevent damage to the optical disc caused by contaminants on the flat surface or by defects in the flat surface. The projections are sized to provide adequate clearance between the disc and the flat surface, while minimizing interference between the projections and components of optical disc readers and drives. One or more projections or projection types may also be configured with a flat surface at a point of contact to an external surface to enhance weight distribution, for example. The projections or projection types that may be configured to enhance aerodynamics.

Abstract: Disc-shaped storage medium provided with identification means to distinguish CD from the other storage medium such as CD-ROM, wherein the identification means comprise raised letters, depressions, projections or a selective combination of thereof formed on a top surface of a substrate so as to be sensed as user touch them with the finger tip. More specifically, the disc-shaped storage medium provided with identification means to distinguish CD from the other storage medium such as CD-ROM, wherein the identification means comprise raised letters, depressions, projections or a selective combination of thereof formed on the top surface of the substrate in the vicinity of its central opening and/or in the vicinity of an outer peripheral edge of the substrate.

Abstract: The present invention relates to a disc-shaped optical recording medium, which includes at least one sputter layer formed through a sputtering method, having an arrangement in which the inner circumference of the above-mentioned sputter layer is located on the inner side from a stack ring, and to an optical recording medium which is formed by bonding a pair of disc-shaped substrates, each having a hole in the center portion thereof, to each other through a bonding layer made from an adhesive with a print layer being formed on one side. The inner edges of the above-mentioned bonding layer and print layer are located within a range from 18 mm from the center of the above-mentioned hole.

Abstract: In an optical disc in which an information signal is recorded/reproduced by irradiating a laser beam to a disc substrate 1 in which an information signal portion 1c has been provided on one principal plane from the side where the information signal portion 1c exists, a clamp reference surface 3a is set to the information signal portion 1c side of a replica substrate 1a constructing the optical disc. The clamp reference surface 3a is set to a flat surface and a thickness of the replica substrate 1a in a clamping area 3 is set to be larger than that of the convex-shaped replica substrate 1a in an information recording area 4. The replica substrate 1a in which a periphery of a center hole 1b is thicker than the information recording area 4 is used.

Abstract: An optical recording medium wherein a land and a groove are formed in both front and rear surfaces of a circular disk-like substrate respectively, at least a recording layer and a dielectric layer are formed on the surfaces of the substrate, and a hub is provided in only one of the surfaces and recording/reproducing are conducted by using a flying optical head, the optical recording medium being characterized in that in a state that the medium is supported by the hub so that the hub-attached surface directs downward, and in a region from the innermost periphery to L/3, where L is a distance from the innermost periphery to the outermost periphery of a recording/reproducing area, the center of curvature in a radial direction of that region exists at an opposite side with respect to the hub-attached surface of the optical recording medium, whereby the optical recording medium of high reliability wherein the distance between the flying optical head floating above the surface of the recording medium and the surfac

Abstract: An optical information disk with an excellent mechanical precision is provided. Also provided is a multi-layer optical disk having a plurality of data layers wherein every data layer exhibits sufficient properties in reading. In addition, such multi-layer optical disk is provided at a low cost. The optical information comprises a disk-shaped substrate or a pair of disk-shaped substrates, and at least one annular data layer for storing at least recorded information and at least one annular resin layer disposed on said disk-shaped substrate or between said pair of disk-shaped substrates. In this medium, at least one of the substrate(s) has a configuration such that its surface facing toward the data layer is convex, and at least one of said resin layer(s) is formed such that it is thicker near its outer periphery compared to the region near its inner periphery.

Abstract: An improved optical disc is provided that comprises a substantially transparent substrate, one surface of which carries optical data structures comprising pits and lands radially outward of a clamp area of the disc. In the clamp area a protrusion structure is provided above the first surface to create a clamp thickness greater than the thickness of the rest of the disc. In accordance with the principles of the present invention, only a portion of the clamp area is covered by the protrusions, which emulate a disc having a clamp area of greater thickness. In order to reduce warping caused by shrinkage of material added to the clamp area, the amount of material used to form the protrusions is less than 5% of the amount of material used to form the rest of the clamp area.

Abstract: The invention is directed toward techniques for creating molded substrates for use in various different data storage media. The molded substrates have improved thickness profiles that can improve media quality, and in some cases facilitate higher data storage densities. In many cases, the improved thickness profile is a thickness profile that has improved flatness. Mechanical flatness or optical flatness can be achieved. In particular, optical flatness is desirable for substrates used in holographic data storage media having a sandwiched construction.

Abstract: In an optical recording medium comprising a substrate including parallel extending lands and grooves on one surface thereof, the grooves serving as recording tracks, and the lands being formed with prepits, the height HP of the land disposed between the prepit and the groove divided by the height HL of the land in a prepit-free region, both as measured from the groove bottom, i.e., HP/HL ranges from 0.25 to less than 1. This enables to significantly increase the recording density of the medium without a substantial cost increase.

Abstract: Disclosed herein are data storage media and methods of making the same. The data storage media, comprises: primary surface features disposed on at least one side of said data storage media; and secondary features superimposed over at least a portion of said surface features. In one embodiment, the method for manufacturing the data storage media comprises: disposing an identifier layer onto a surface of a stamper, said stamper having primary surface features on a first side of said stamper opposite said identifier layer; forming secondary features on an exposed surface of said identifier layer; installing said stamper into a mold; injecting a molten plastic material into the mold, wherein said molten plastic physically contacts said first side; cooling said plastic to form said data storage media, such that a positive image of said primary surface features and of said secondary features are formed into at least a portion of a surface of said plastic; and releasing said data storage media from said mold.

Abstract: The present invention relates to a high-density disk that is structured to prevent a collision of an optical pickup's objective lens with the high-density disk if the disk is placed upside down in a disk device that is able to record and reproduce signals to/from the high-density disk. A high-density disk recording medium according to the present invention is structured such that, wherein a recording layer having high-density pit patterns is offset from a center plane of disk thickness, both sides of a clamping zone bisected by the center plane have differing thicknesses. One or both sides may protrude from surface of the disk recording medium, or one side of the clamping zone may protrude from the surface while the other side is indented below the surface.