Abstract: A system includes optical discs of a first type and optical discs of a second type having a transparent substrate with a thickness greater than that of the transparent substrate of the optical discs of the first type. The system further comprises a scanning device which is capable of scanning optical discs of both types and which comprises an actuator and an objective for focusing a radiation beam passing through the substrate of an optical disc so as to form a scanning spot (S) on an information surface. The actuator comprises a first actuator section and a second actuator section including the objective, which second actuator section is movable relative to the first actuator section. The system further comprises compensation means for compensating for the difference in thickness (t.sub.2 -t.sub.

Abstract: A turntable is a table mounted to a shaft (4) of a spindle motor and the turntable supports a laminated disc thereon and drives the disc in rotation. The laminated disc includes a lower disc and an upper disc stacked on the lower disc, and is supported on a disc-supporting surface. When the disc is loaded on the turntable, a fitting member fits into the center hole of the laminated disc for centering the laminated disc with respect to the shaft. The fitting member fits the center hole of the lower disc when the laminated disc is supported on the disc-supporting surface. The turntable may include a tapered member which guides the laminated disc to the disc-supporting surface. The laminated disc includes lower and upper discs each having an edge which defines the center hole. The corners of the edges are cut away along a circumference of the center hole. The upper and lower discs are placed together so that the cut-away corner directly face each other.

Abstract: A spindle for providing precise radial location of a disk includes a spindle having a key that extends from one end thereof. The disk includes a hub having a shape that is similar to that of the spindle with a key notch disposed on the peripheral edge thereof that is shaped similar to that of the key in the spindle. The key has two surfaces that come together at an angle to an apex, which apex extends downward away from the spindle and radially outward. The surfaces of the key notch on the hub are longer than that of the key, such that the surfaces of the key can mate with the surfaces of the key notch and slide therealong, such that the spindle is maintained in the center of the hub.

Abstract: A vertically disposed drive spindle (5) rotates turntable (6) supporting a substrate (7) at high speed, the turntable having a smaller diameter than the substrate. Coaxial with the turntable (6), a centering ring (10) having a frustoconical inside surface can be raised vertically between a lower and upper position. The latter has on its upper side a greater diameter and on its lower side a smaller diameter than the substrate (7). In its lower position the centering ring (10) is at a distance from a substrate (7) lying on the turntable (6), but in its upper position its inside surface supports the substrate (7) at an axial distance above turntable (6).

Abstract: A display device is provided comprising one or more masking discs being printed on a surface and a transparent area for viewing printed matter on a substrate disc such as a compact disc. A masking disc or a protective layer includes a bushing extending through a central hole of the compact disc so that each masking disc and substrate disc are rotatably mounted relative to each other. The bushing cooperates with a securing disc to maintain the masking discs and substrate disc together. The securing disc includes means for mounting the display device on a substrate independent of the display device.

Abstract: A plate made of a magnetic material is secured to an optical disk so that it closes a central hole formed in a disk substrate. An optical disk chucking mechanism for chucking the optical disk to a disk table attracts the magnetic plate by the magnet to cause a platen to abut to the disk substrate and a tapered portion to abut to the inner side of the central hole so that the optical disk is restricted in position and is held. The optical disk and optical disk chucking mechanism restrict the loading position of the optical disk on the disk table independently of the mounting position of the magnetic plate on the disk substrate.

Abstract: A disc-shaped recording medium is provided in which the coupling state between the disc substrate and the hub structure may be positively maintained even after repeated mounting and dismounting operations of the recording medium from a recording/reproducing apparatus for prohibiting the hub structure from being disengaged from the disc substrate. The disc-shaped recording medium includes a disc substrate 2 having an information recording section for recording information signals and a center aperture 5, a hub structure 3 and a clamping member 4. The hub structure has a magnetic plate 6 magnetically clamped to a disc table by a magnetic attracting means and an outer rim fitting member 9 slightly larger in diameter than the inner diameter of the center aperture 5 of the disc substrate 2 having plural elastically flexible engagement pieces 13 for being unified to the outer rim of the magnetic plate 6.

Abstract: According to the present invention, a blank of an aluminum alloy is partially cut so as to form several disks maintained in the blank by portions of the remaining uncut aluminum. This results in the disks being supported in the blank during formation of the thin films, yet easily separated from the blank into individual disks after the thin films have been deposited. Therefore, multiple disks can be processed during a single manufacturing step.

Abstract: An upper clamping device and a lower clamping device are provided for clamping a double-sided optical disc in cooperation with the upper clamping device. An annular holder is axially movably provided in the upper clamping device. A plurality of spheres are radially movably mounted on the holder. A hub having a slant at a periphery thereof is axially movably provided. When the hub is downwardly moved the slant urges the spheres to engage them with an inside wall of a center hole of the optical disc. Thus, the optical disc is centered.

Abstract: In an optical disk according to the present invention, a part of a disk is heat pressed to thereby connect a clamping plate to the central part of the disk. The heat pressed part of the optical disk is heat pressed into a discontinuous form during connection of the clamping plate to the disk. An apparatus for manufacturing such an optical disk connects the clamping plate to the disk by heat pressing a part of the disk onto which the clamping plate is mounted. This is carried out by a pressing surface of a heat press member. The heat press member is provided in its annular pressing surface with radially elongated grooves, so as to divide the annular pressing surface into a plurality of portions by the grooves.

Abstract: A method for mounting a magnetic plate on a disc substrate. The method includes the steps of placing the magnetic plate within a housing recess formed in the disc substrate, abutting a horn of an ultrasonic wave generating unit generating torsional vibrations on a rim of the housing recess of the disc substrate under application of a predetermined pressure, and ultrasonically forming a protrusion directed towards an inner space of said housing recess for mounting the magnetic plate on the disc substrate by protrusion.

Abstract: Resin, typically polycarbonate is injection molded into a disc substrate under select conditions, for example, at a mold temperature of 100-160.degree. C., an injection velocity of 100-120 g/sec., and a pressure of 10-60 kg/cm.sup.2, such that the birefringence of a radially inner portion of the substrate is higher by about 15-50 nm than the remaining substrate. A center hole is perforated in the substrate and a hub is attached to the substrate around the center hole. At the end of hub attachment, the substrate has a uniform distribution of birefringence over the entire area. Any increase of DC modulation is thus avoided.

Abstract: Turntable (10) has a turntable bottom (19) and a turntable wall (20) which together define a locating space (21) in which the hub (7) of an information disc is engageable, and in which it is centered by means of a centering member (12) and clamped by magnetic clamping means. At the circumference of the locating space a centering wall (26) is provided, which wall has an inwardly sloping surface (27). The dimensions of the various parts, the field strength of the magnetic means and the coefficients of friction of the cooperating materials of the hub and the turntable are selected in such a way that, once an information disc has reached a position in which the free end of the centering member (22) has engaged the centering hole (17) of the information disc, the outer wall (28) of the hub (7) is situated above the sliding surface (27) of the turntable.

Abstract: An information recording disk formed from two substrates with a stepped central opening for receiving a hub within the stepped recess of at least one of the substrates is provided. In one embodiment, the central aperture of the first substrate is larger than the central aperture of the second substrate to form the stepped recess. In another embodiment, at least one substrate has a stepped surface defining a central aperture and a hub structure is mounted within this stepped recess to reduce overall thickness of the disk.

Abstract: Information recording discs comprise a disc substrate having a recording layer on one side thereof, one hub having an insertion portion to be inserted into a center hole of the disc substrate and a flange portion to cover the disc substrate in the vicinity of the center hole, at least an apex of the insertion portion being composed of a magnetic material, the hub being inserted into the center hole so that the flange portion is positioned on the recording layer side of the disc substrate, and an adhesive layer is provided between the flange portion and the disc substrate. By this construction, a portion of the hub which protrudes from the back surface of the disc substrate, facing toward the spindle of a turn table can be altered in dimension and/or the diameter of the protrusion portion of the hub can be made smaller than that of the center hole of the disc substrate.

Abstract: Selecting different sectors in a storage medium using switches on the storage medium, instead of programming the instrument reading the storage medium. Each switch has a switching material. The switching material can be located at more than one interchangeable position. The position determines the priority of its corresponding sector as compared to other sectors. The location of the switching material is determined electronically. Switching materials suitable for the present invention include a reflective material, an opaque material, a reflective concave material, a convex lens, a prism, a set of lines, a magnetic material and a flexible reflective membrane.

Abstract: An inner peripheral resin ring having a centering aperture unitarily molded with the inner periphery of a metal plate of a disc hub is given an anti-static effect to prevent build-up of a static electric charge. An inner peripheral resin ring (14) having on its center a centering aperture (17) unitarily molded with the inner periphery of the metal plate (12) of a disc hub (11) is formed by the molding process of a resin which is highly wear-resistant and relatively conductive.

Abstract: The present invention discloses a disc having an information signal surface on which a replica of information signals is formed by a stamper provided in a metal mold, and a manufacturing method of the disc. The disc includes a disc substrate having a generally flat surface on which the replica of the information signal is formed, a center through hole formed at a center thereof and a ring groove inevitably formed as an inverted replica by a shape of a collar of a retainer which is provided in the metal mold to support the stamper. The ring groove concentrically divides the generally flat surface into inner and outer surfaces. A reflecting layer is provided on the generally flat surface for reflecting reading light from a reproducing apparatus. Further, a protecting layer is provided on the reflecting layer for protecting the reflecting layer.

Abstract: A disc for recording information signals includes a disc substrate of a synthetic resin having a center hole and an information signal recording layer formed on one major surface and a magnetic plate arranged on the major surface for closing the center hole. A recess for accommodating the magnetic plate is formed on the major surface of the disc substrate for surrounding the center hole. At least a part of the rim of the recess is thermally deformed for forming one or more lugs for holding the magnetic plate disposed in the recess with respect to the disc substrate by the lug(s).

Abstract: Information recording discs comprise a disc substrate having a recording layer on one side thereof, one hub having an insertion portion to be inserted into a center hole of the disc substrate and a flange portion to cover the disc substrate in the vicinity of the center hole, at least an apex of the insertion portion being composed of a magnetic material, the hub being inserted into the center hole so that the flange portion is positioned on the recording layer side of the disc substrate, and an adhesive layer is provided between the flange portion and the disc substrate. By this construction, a portion of the hub which protrudes from the back surface of the disc substrate, facing toward the spindle of a turn table can be altered in dimension and/or the diameter of the protrusion portion of the hub can be made smaller than that of the center hole of the disc substrate.

Abstract: An optical recording disc which includes a pair of recording disc substrates opposed to each other with a space there between with a hub situated at the central portion of the disc substrates so that there is formed the closed space between the disc substrates, thereby providing a dual sided recordable optical recording disc. The hub may be formed by a pair of hub halves. There is disposed an annular inner spacer and annular outer space around the hub so as to separate the pair of recording disc substrates.

Abstract: An information recording disk formed from two substrates with a stepped central opening for receiving a hub within the stepped recess of at least one of the substrates is provided. In one embodiment, the central aperture of the first substrate is larger than the central aperture of the second substrate to form the stepped recess. In another embodiment, at least one substrate has a stepped surface defining a central aperture and a hub structure is mounted within this stepped recess to reduce overall thickness of the disk.

Abstract: An optical recording disk in which a transfer layer having grooves made of ultraviolet setting resin is laminated on the surface of a substrate, and in which a recording layer is laminated on the transfer layer, the optical recording disk comprises a peeling protrusion projectingly provided on the inner circumferential side of the transfer layer.

Abstract: A transparent substrate has an information layer on an entirely flat side, and a centering member on the other side adapted to cooperate with centering means of an apparatus for inscribing and/or reading the disc. The centering member may be glued in place and have an aperture for engagement by an apparatus spindle.

Abstract: An optical recording element comprising a transparent supporting plate, a dye-containing recording layer and a first reflective layer which is applied to a recording layer. The element has a ROM (read only memory) region containing information which can be read optically and a RC (recording) region in which information can be recorded and read optically, the recording layer extending over the ROM and RC regions and a second reflective layer being present in the ROM region between the recording layer and the substrate.

Abstract: Improvement in an information recording medium comprising two transparent resin substrates combined with each other, at least one of which has a recording layer provided on the inner surface thereof, two hubs mounted over the center hole of said disc substrates on both sides thereof, each hub having a insertion portion to be inserted into said center hole and a flange portion to cover a portion of said disc substrate in the vicinity of said center hole, wherein a notch is provided on the peripheral surface of each hub, adhesive layers are formed at least in the notch, between the inner peripheral surface of the center hole and the outer peripheral surface of the insertion portion of said hubs and between the hubs and a specific photo-curable composition may be used for the adhesive layer.

Abstract: The invention is directed to a two-sided magneto-optical recording disk having reduced birefringence comprising a pair of single-sided magneto-optical recording disks, the entire recording sides of which are adhered together by means of a continuous layer of polymeric adhesive. An external mechanical laminating pressure in a vacuum is applied to the non-information areas of the a magneto-optical disk.

Abstract: A compact disc (CD) or CD-ROM disc having at least one surface region containing a field of digitally encoded, reproducible data, outside of a central region of the disc is provided with a second non-volatile read/write memory IC chip or memory device, e.g., an E.sup.2 -PROM, embedded in the central region adjacent to the data field. Input/output (I/O) terminal is also embedded in the central region and provides for communication with and access to the second nonvolatile memory IC chip device. The terminal has one surface exposed adjacent to the data field for external access by a CD or CD-ROM access player or playback apparatus. The terminal has a series contact engagement means through which access is made by complementary terminal means provided in the player whereby the movement of the disc is terminated and information may be read into or read out of the second nonvolatile memory IC chip device.

Abstract: A process for producing a magnetic hub for an optical disc which is fixed to the spindle of a disc drive by means of a magnetic clamp system, which process comprises positioning and setting an annular metal plate composed of a ferromagnetic substance having burrs on one side thereof produced by punching in a mold and then injecting a resin into the mold.

Abstract: An optical storage medium is disclosed. In general, the storage medium includes a substrate, with a first, expansion layer, a second, reflective layer bonded to the first layer, and a third, retention layer bonded to the second layer, opposite the first layer. An opto-electronic system for recording data is also disclosed, along with a method of manufacture of the storage medium.

Abstract: An optical storage medium is disclosed. In general, the storage medium includes a substrate, with a first, expansion layer, a second, reflective layer bonded to the first layer, and a third, retention layer bonded to the second layer, opposite the first layer. An opto-electronic system for recording data is also disclosed, along with a method of manufacture of the storage medium.

Abstract: A hub to be attached to the central portion of a recording medium comprises a flat plate-like body made of a metallic material, and an annular resinous body firmly attached to the flat plate-like body by insert-molding, wherein at least one bent portion with an opening for connecting the annular resinous body to the flat-plate-like body is formed in the flat plate-like body so that the opening is in parallel to the upper or lower surface of the flat plate-like body.

Abstract: The disclosed magnetic recording and/or reproducing apparatus uses a disc-shaped magnetic recording bearing medium having a magnetizable member mounted at its center. The apparatus includes a recording and/or reproducing magnetic head and a spindle for rotating the record bearing medium. The spindle is provided with a permanent magnet for attracting the magnetizable member of the medium. The permanent magnet is magnetized in a radial direction of the spindle.

Abstract: The present invention relates to a master disk used as a matrix for manufacturing a stamper by transferring, which is used for reproducing an optical disk, the master disk according to the present invention is provided with an appointed number of calibration tracks formed at an appointed pitch symmetrically relative to the center of guide tracks in the area including a position corresponding to an edge portion of a center hole of the stamper, whereby the center hole of the stamper can be easily formed concentrically with the guide tracks of the master disk and the tolerance of diameter of the center hole or the eccentricity between the center of the center hole and the center of the guide track can be easily measured.

Abstract: An information recording medium for writing and/or reading information by means of a laser beam comprises an information recording disc and a magnetizable hub. The information recording disc has a circular hole at its center, and the magnetizable hub is fitted into the hole of the disc. The magnetizable hub comprises a boss and a flange and has a hole at its center for insertion of a spindle. The boss of the hub has at its bottom a diameter being equal to or larger than the diameter of the circular hole of the recording disc. The magnetizable hub is pushed into the circular hole of the recording disc, whereby the hub is firmly fitted into the hole of the disc. The boss of the magnetizable hub may have an outwardly extended protrusion or raised portion at its bottom. The boss of the magnetizable hub may be divided into three or more separate portions.

Abstract: A molded center core for a flexible recording disc and a related method of manufacture are provided. The disc includes a recording media sandwiched between an injection molded center core having a metal insert, and an injection molded ring. The core and ring are ultrasonically welded to hold the media in place. The method includes the steps of: injection molding a separate plastic center core with a metal insert therein; injection molding a separate plastic ring; locating the center core/insert combination in the central opening of the recording media to abut a first surface of the media; locating the molded ring on the center core to abut a second, opposite surface of the media; and permanently connecting the core and ring.

Abstract: An optical recording disc which includes a pair of recording disc substrates opposed to each other with a space therebetween, with a hub situated at the central portion of the disc substrates so that there is formed the closed space between the disc substrates, thereby providing a dual sided recordable optical recording disc. The hub may be formed by a pair of hub halves. There is disposed an annular inner spacer and annular outer spacer around the hub so as to separate the pair of recording disc substrates.

Abstract: Information carrier includes an optically readable disc with a center hole and a hub with radially resilient clamping members which extend through the center hole to retain it on the disc and center it with respect to the information carrying surface on the disc. The hub further carries a sleeve which centers it on a spindle, and a magnetizable clamping ring for retaining it on a turntable, which carries permanent magnets. In an information carrier having two discs sandwiched together, the clamping members of each hub extend between the clamping members of the other hub and pass through the center holes of both discs to engage the opposite disc and retain the discs to each other.

Abstract: A disc drive for a disc including a disc rotating apparatus comprising a rotating shaft for being received within a first aperture of the disc. A spindle is affixed to the shaft. The spindle has a surface disposed in a plane perpendicular to the shaft, for supporting the disc. The disc drive includes a position controlling member received in a second aperture of the disc, a rigid member for controlling the position of the position controlling member, and a biasing member for urging the rigid member in at least one direction so that the position controlling member engages the disc. A centering force to center the disc on the disc rotating apparatus is produced due to the action of the position controlling member on the disc. The biasing member may be configured so as to act upon the rigid member in an additional direction to produce an additional centering force component when the position controlling member engages the disc, thus urging sides of the first aperture of the disc against the rotating shaft.

Abstract: An optical information recording disk having an improved eccentricity and reduced center hole wear. A metal plate lamination hub member is inserted into and fixed in a central hole in the substrate of the disk. The metal plate lamination member is formed of a metal plate and a resin hub member having center holes dimensioned and aligned such that the center hole in the metal plate forms the center hole of the disk. The metal plate and the resin hub member are attached to one another by ultrasonic welding. The metal plate may have a hardened layer at least around its center hole.

Abstract: A transparent substrate has an information layer on an entirely flat side, and a centering member on the other side adapted to cooperate with a centering device of an apparatus for inscribing and/or reading the disc. The centering member may be glued in place and have an aperture for engagement by an apparatus spindle.

Abstract: An optical disc in which distortion due to temperature change is inhibited has a magnetic positioning disc 3 of specified diameter mounted at the center of the disc substrate 1 having an information recording layer 2 on a specified radial area. The positioning disc is bonded to the disc substrate by an element(s) made of a material whose thermal expansion coefficient is almost equivalent to that of the disc substrate.

Abstract: A method for manufacturing an optical information recording disk having a reduced eccentricity between the center hole of the disk and the recorded track. A transparent circular substrate is provided having a large circular hole. A metal lamination disk member is formed having an outer diameter larger than the inner diameter of the hole in the substrate and an inner diameter smaller than the inner diameter of the hole in the substrate. The metal lamination disk member is placed on the substrate with an adhesive and positioned so that the center hole in the lamination member is concentric relative to the substrate, whereupon the adhesive is hardened. A molded circular plate is then concentrically mounted having a transfer surface on a main surface of the circular substrate through a setting resin in a liquid phase, which is then hardened.

Abstract: An optical record carrier having a surface layer which includes a substantially circular information track structure, such surface layer extending without interruption substantially up to the center of the track structure. When the record carrier is supported on a rotating turntable and scanned by a scanning beam producing a scanning spot having a width transverse to the track direction of at least a few times the period of the track structure, a diffracted beam is produced by the track structure in a direction transverse to the local track direction. A radiation-sensitive detection system in the path of the diffracted beam produces output signals indicating any centering error between the center of the track structure and the axis of rotation of the turntable. Such signals can be employed to control positioning means to position the record carrier on the turntable so as to eliminate such centering error.

Abstract: Method of providing a substrate of an optically readable information disc with an optically detectable structure, mould for use in the method, apparatus for carrying out the method, and information disc manufactured in accordance with the method.Substrate (3) is provided with a disc hub (8) comprising disc-centering means (9) which serve to center the finished information disc (17) on the drive spindle (27) of a drive apparatus. The intermediate product comprising the substrate (3) and the disc hub (8) is centered on the base (1A) of the mould by cooperation between the base-centering means (17) and the disc-centering means (9). This may be effected by the use of an auxiliary centering means (12) which is in contact with a wall (14) of a central centering hole (11) in the disc hub (8) and with a wall (13) of a central centering recess (10) in the base (1A).

Abstract: An optical disk comprising a disk-like body having two base plates made of synthetic resin and two recording layers formed on the base plates, respectively. The body is formed by bonding the base plates, with a spacer interposed therebetween, such that the recording layers face each other. The disk further comprises two centering members, each projecting from the surface of the center portion of each base plate. Each centering member is made of synthetic resin, and one magnetic member is mounted on the centering member. The centering member is inserted in a hole formed in the center portion of the body. The centering member has a center hole defining the center of rotation of the body, and also a recess for holding the magnetic member. Four through-holes are formed in the bottom of the recess. The magnetic member has four projections and is held in the recess, with the projections inserted into the through-holes of the bottom of the recess.

Abstract: A disc drive for a disc including a disc rotating apparatus comprising a rotating shaft for being received within a first aperture of the disc. A spindle is affixed to the shaft. The spindle has a surface disposed in a plane perpendicular to the shaft, for supporting the disc. The disc drive includes a position controlling member received in a second aperture of the disc, a rigid member for controlling the position of the position controlling member, and a biasing member for urging the rigid member in at least one direction so that the position controlling member engages the disc. A centering force to center the disc on the disc rotating apparatus is produced due to the action of the position controlling member on the disc. The biasing member may be configured so as to act upon the rigid member in an additional direction to produce an additional centering force component when the position controlling member engages the disc, thus urging sides of the first aperture of the disc against the rotating shaft.

Abstract: A rotary disk including a recording and reproducing sheet, and a hub formed of hard material secured to a central portion of the sheet. The hub comprises a center opening adapted to receive a main spindle of a turntable of disk driving means, two planar surfaces arranged in an intersecting relation to each other and formed on a projecting wall portion of the center opening, and a resilient member located in a position facing the two planar surfaces for pressing the spindle against the two planar surfaces. Even if the recording and reproducing sheet of the rotary disk is a thin magnetic sheet, there is no risk of damage of the sheet. When the rotary disk is set on the turntable, the center of rotation of the rotary disk and the center of rotation of the turntable can be automatically brought into alignment with each other.

Abstract: An information medium comprises an information disc 1 which can be rotated inside the enclosure 5 and which carries a hub 2 which extends through an opening 9 in a main wall 6 of the enclosure with some clearance. Radial displacements of the information disc are limited by elastic means between the hub and the edge 23 of the central opening in the main wall.

Abstract: An optical recording and/or reproducing disk includes a disk substrate and a chucking hub, in which the chucking hub is formed of a synthetic resin ring having formed on its lower surface a welding portion and on its upper surface a ultrasonic welding horn contact portion and a disk-shaped metal plate made of a magnetic material and forming near its outer peripheral portion a low stepped portion, the synthetic resin ring being integrally formed on the low stepped portion by a resin molding and the chucking hub being fixed to the central portion of the disk substrate by welding a welding portion of an resin ring by using the ultrasonic welding horn.