Abstract: A system and method for maintaining a prescribed track pitch in an optical storage system wherein a second radiation beam is aligned a desired distance from a first radiation beam, the first radiation beam being controllably steered to follow a previously written data track on a record carrier used within the optical storage system. A write alignment servo aligns the second radiation beam the prescribed distance from the first radiation beam in response to an offset signal. The offset signal is generated by optically measuring the distance between a pair of calibration tracks that have previously been placed on the disk so as to have the desired track pitch therebetween. The effect of variations or drift occurring in the optical or electrical components of either the write alignment servo or the optical track pitch measurement system is significantly reduced by regularly calibrating against the fixed track pitch of the calibration tracks.

Abstract: A system and method for optically measuring and maintaining track pitch in an optical storage system. A set of at least four calibration tracks, each having a prescribed track pitch or distance therebetween, are precisely placed on a record carrier of the optical storage system during the manufacture thereof. When this record carrier is subsequently inserted into the optical storage system, the track pitch of a select pair of the calibration tracks is optically measured, and an offset signal is generated in response to this measurement. This offset signal is used within the optical storage system for controllably positioning a second radiation beam with respect to a first radiation beam, the first radiation beam being directed to follow a previously written data track on the record carrier.

Abstract: An apparatus for clamping and unclamping an optical disk in an information storage and retrieval device having removabe media. The apparatus has rotating and a non-rotating disk support assemblies, the non-rotating disk support assembly being attached to an elevator which reciprocatively raises and lowers the rotating and non-rotating disk support assemblies. The rotating disk support assembly is magnetically clamped to the non-rotating disk support assembly by an electromagnet during the loading and centering operation. The rotating disc support assembly has a centering stem which cooperates with a hole in the device spindle to center the rotating disk support assembly relative to the device spindle. In the preferred embodiment, the disk has a flexure and a tapered disk centering hub which cooperates with a taper on the hole in the device spindle to center the disk relative to the device spindle.

Abstract: A system and method for optically measuring and maintaining track pitch in an optical storage system. A set of at least four calibration tracks, each having a prescribed track pitch or distance therebetween, are precisely placed on a recording medium of the optical storage system during the manufacture thereof. When this recording medium is subsequently inserted into the optical storage system, the track pitch of a select pair of the calibration tracks is optically measured by maximizing the amplitude of a data read radiation beam, and an offset signal is generated in response to this measurement. This offset signal is used within the optical storage system for controllably positioning a second radiation beam with respect to a first radiation beam, the first radiation beam being directed to follow a previously written data track on the recording medium.

Abstract: A beam alignment signal processing system wherein a true beam position error signal is generated regardless of beam intensity. This beam position error signal is used within a beam alignment system that maintains a desired alignment between first and second beams traveling in parallel along a desired optical path. A detector senses the position of the beams as the beams (or portions of the beams) are directed onto a surface thereof. The detector generates a set of position signals that indicate the position at which a beam, or at which an energy centroid associated with a plurality of beams, falls upon the detector surface. A first set of position signals is generated corresponding to the position of the first beam on the detector surface with the second beam turned off. These signals are stored in signal storage means. The second beam is turned back on, and a second set of position signals is generated corresponding to the position of the centroid of the first and second beams on the detector surface.

Abstract: A shared encoder/decoder circuit for use with a Reed-Solomon coding scheme of an optical disk storage system. The optical disk system includes a drive adapted to permanently store data on a removable platter. Prior to recording a data byte on the platter, the data is encoded with a Reed-Solomon code. When the data is read from the disk, it is decoded and error correction syndromes are generated. The same circuitry is shared for performing the encoding and decoding functions. This circuitry includes independent sets of a RAM, coupled to one input of an exclusive OR (modulo two sum) adding circuit. The output of the adding circuit is fed back to an input to the RAM. Two multiplier circuits are coupled to the output of the RAM. A product of one is tied to one input of the modulo two addition circuit.

Abstract: An unconstrained removable protective cover for optical disks. With this apparatus a transparent protective cover can be mounted to an optical information recording disk wherein the different thermal expansion coefficients of the disk and the protective cover will not result in read write errors due to warping of the protective cover. An inner spacer ring is fixedly bonded to the inner diameter of the disk substrate and the protective cover. However, on the outer perimeter of the disk, a U-shaped spacer ring is fitted thereon and fixedly mounted to the outer perimeter of the transparent protective cover. This allows the transparent protective cover to expand and contract relative to the disk substrate by lateral movement of the spacer ring relative to the disk, without warping of the protective covering. A plurality of methods of mounting the outer spacer ring to the protective covering are disclosed.

Abstract: A centering mechanism for centering the disk recording medium over the spindle of a rotating disk storage system is presented. The invention consists of a centerpiece in the disk having three or more fingers pointing in the direction of insertion and curved away from the center of the disk. As the disk is inserted over a tapered spindle, one side or the other of the fingers will contact the spindle and center the disk as it moves toward the tapered spindle. The bottom edge of the center hole of the disk is rounded to form a stop for the fingers. The fingers bend as the disk is inserted, and this stop ensures that the fingers will not bend too far and break. When the disk is fully inserted, all the fingers around the circumference of the hole are contacting the tapered spindle hub and are also bent back against the stop surface on the disk to provide good centering.

Abstract: An automatic load/unload apparatus is disclosed for handling of workpieces that must be removed from protective cartridges prior to use. In particular, the workpiece to be handled is an optical disk adapted for use in an optical disk information storage device. The load/unload apparatus includes a guide frame, a cartridge pull-in tray, a cartridge insert separator, reciprocating means for moving the pull-in tray and separator, and an elevator assembly. During a load operation, the cartridge is inserted into the information storage device wherein the load/unload apparatus is housed. The cartridge is received in the guide frame and opened, allowing the pull-in tray to be slideably removed. The disk is separated from the pull-in tray and raised by the elevator assembly to a desired position. An unload operation proceeds in a reverse sequence.

Abstract: A flexible hub for a disk is described. The disk includes a relatively large center hole into which a flexible planar member is mounted or clamped. The size of the flexible member is slightly larger than the hole, thereby requiring that the flexible member be slightly bowed or flexed in order for it to fit within the hole. The flexible member is preferably attached to the disk at three respective equi-angularly spaced locations around the periphery of the hole. In the center of the flexible member is a collar adapted to receive a protruding spindle neck from a spindle mechanism upon which the disk is mounted. The end of the spindle neck and the inside wall of the collar are tapered at the same angle. Insertion of the spindle neck into the collar thereby forces alignment or centering of the center of the collar with the longitudinal axis of the spindle neck.

Abstract: A hermetically sealed cassette cartridge is disclosed, which encapsulates an optical disk suitable for use in an optical information recording and retrieval device. The cassette cartridge comprises a structural casing having a cavity for containing said recording medium and a spindle hub adapter for rotating the disk for data access. Data transfer is accomplished through a flexibly mounted transparent window, said window serving not only as a hermetical seal but also to alleviate the need for a thick dust defocusing layer on the said encapsulated recording medium.

Abstract: An improved cooling system for electronic components wherein an air supply housing with two openings cooperates with a manifold with one opening to allow air distribution from the air supply housing through the manifold to a card cage both while the manifold is closed for normal operation and while the manifold is extended to allow maintenance of the electronic components. When the manifold is closed for normal operation, the first opening in the air supply housing is blocked by the manifold and air flows into the manifold through the second opening. When the manifold is extended for maintenance, air flows into the manifold through the first opening and the second opening is blocked by a flapper which swings down over the second air supply housing opening.

Abstract: The centering and clamping device consisting: a disk elevator, a disk support, a disk centering assembly, a disk clamping assembly, and a disk rotating assembly. In operation the disk is raised out of the disk insert tray cartridge by the disk elevating means and raised upward to engage a taper on the spindle of the device spin motor, moving upward until the cooperation between the taper on the neck spindle and the tapering on the disk centering collar cause the disk to move laterally until precisely centered on the spindle. Thereafter, the continued upward movement on the disk on the elevator lifting assembly causes a magnet located on the disk support means to come into magnetic contact with a steel plate on the spindle platform, thereby securely clamping the disk to the spindle for rotation. Thereafter, the elevator moved downward and clamping the disk from disk support means, thereby allowing the free rotation of the spindle disk and disk support assembly relative to a stationary elevating means.

Abstract: A magnetic or optical disk load/unload device for automatically centering and clamping a disk to the spindle of an information storage device. The apparatus is comprised of a toggle arm, a toggle arm rotating device, a support base, a support hub having a centering stem and a concentric annular steel ring disposed on its mating surface, a member for clamping the hub to the support base, a spindle having a centering hole on its mating surface and a concentric magnetic material ring on its mating surface, and a spindle rotating motor. In operation, the toggle arm is rotated from a first bent position causing the support base hub and disk located thereon to advance toward the spindle, the hub slidably retained on the base by a of clamping member activated by a cam assembly. Upon full extension of the toggle arm, the hub and disk are centered on the spindle, clamped to same by the magnetic and steel rings.

Abstract: Disclosed is a low cost flexural mechanism upon which tracking mirrors and the like used in optical systems may be mounted. The flexural mechanism is made from a single sheet of metal by placing a desired shape or pattern in the metal. The resulting shape is then formed into a base, mounting surface, and flex arms. The mechanism is stiff in directions other than rotation, has low noise, has low thermal sensitivity, and can be made in any practical size. The flexural mechanism can be designed to place the pivot axis at the center of gravity of the mass being rotated, even when the center of gravity is outside the flexural mechanism.