Abstract: The present invention sets the position of each apparatus of a detecting system and an emitting system without using a reference disk in assembling an optical head. A light signal similar to reflected light of a reference disk is generated by a light modulator comprising a Faraday rotator for rotating a plane of polarization proportionally to the current by setting a solenoid coil having a large Faraday constant set around a piece of glass and electrifying the solenoid coil, a convex lens connected to a mechanism which moves along the optical axis in accordance with the applied current, a target section having a light detecting target with a groove formed on the surface and a light reflecting member set to the groove on the optical axis and connected to a mechanism moving along the radial direction of a disk in accordance with an applied current, so as to perform positioning by using the generated signal as a servo signal.

Abstract: The present invention makes possible the calibration of the tracking error signal and the focus error signal repeatedly when an optical disk drive is in the normal operation mode. Errors (offset and amplitude error) of the focus error signal and the tracking error signal are detected during at least three track jumps by making use of a track jump performed once per rotation of disk in the track following mode. An offset value of the focus error signal is calculated based on the amplitude of a tracking error signal generated during at least two track jumps by adding a positive or negative offset to the original target value of the focus error signal, and values of offset and amplitude error of the tracking error signal are calculated based on a maximum value and a minimum value of a tracking error signal generated during at least one track jump without modifying the original target value of the focus error signal.

Abstract: A digital phase lock loop channel is provided for threshold detection of a pulse width modulated binary data stream that has negative and positive transitions defining one binary state of the data stream. A threshold-establishing and transition-detecting network receives this data stream and provides a first output of one polarity corresponding to the detection of a positive transition, a second output of an opposite polarity corresponding to the detection of a negative transition, and a time-of-arrival output corresponding to a positive and a negative transition. A first and a second digital PLL is provided, each PLL having a transition input, a time-of-arrival input, a phase-error input, a phase error output a data-valid output, and a data output. Each PLL has an internal digital phase detector network connected to receive its transition input and its time-of-arrival input, and each PLL is operable to generate the phase error output therefrom.

Abstract: The present invention provides an optical disk carrier having the same length and width as an ISO standard cartridge but with a reduced thickness and further having the same sensing and handling features as are found on a conventional, full-thickness cartridge. When reduced-thickness carriers are used in an automated optical storage and retrieval library, the storage density of the library can be significantly increased.

Abstract: An error tolerant detection of multibit synchronization characters within data blocks in a data storage system. Each detected prospective multibit synchronization character is compared to an expected multibit synchronization character for an identical match and for a match which includes a variation of no greater than two adjacent bits. A synchronization character is then considered to be identified in response to a successful exact comparison or, if relaxed detection is enabled, in response to a successful comparison indicating that the detected prospective multibit synchronization character does not differ from the expected multibit synchronization character by an error greater than two adjacent bits. For Read While Write operation in which it is imperative that the synchronization characters be written initially without error, the relaxed detection scheme may be selectively disabled, requiring the synchronization characters to achieve an exact match with the expected synchronization character.

Abstract: The present invention provides machine and human readable information for a data cartridge or other item to be stored. In one embodiment, a label, on which human readable information is printed or similarly marked, is applied to cover an indicator area of the cartridge. The indicator area of the cartridge has recesses formed therein; corresponding positions on the indicator area of the label overlay the recesses and be either open or closed. An open position allows a mechanical, spring-loaded finger on a data drive to engage the exposed recess and activate or deactivate a connected switch. Information, matching the printed human readable information, can thus be encoded in the label and machine read by the data drive.

Abstract: An automated storage and retrieval system includes an accessor device to magnetically hold a stored item while the item is transported within the system. To sense the presence of a magnetically attractable label on the item, the device generates a pulsed signal having a first strength. The reluctance of the magnetic field is compared with a base value; if the comparison indicates that a label is present, the device generates another pulsed signal having a greater strength to "lock" the item against the accessor. The device then generates another pulsed signal having a reduced strength to maintain and hold the item against the accessor during transportation. Less power is used and, therefore, less heat generated.

Abstract: The present invention ensures successful focus acquisition in an optical disk drive independent of a travelling speed of an objective lens at the time when a focus servo circuit loop is closed. The present invention provides sending a signal to a focus actuator for bringing an objective lens close to an in-focus position while a focus servo circuit loop is opened; closing the loop by shutting off the signal sent to the focus actuator; adding an offset of a predetermined level to the focus error signal; detecting that the focus error signal to which the offset is added reaches a predetermined level; and closing the loop when it is detected that the predetermined level is reached, and gradually decreasing the value of the offset to be added to the focus error signal.

Abstract: Fast formatting of DASD emulating sectors on optical media is provided to reduce initialization time. Rather than format each track media when a new surface of an optical media is mounted in an optical storage library, a table is created on the media containing a set of entries for each track on the media surface. During initialization, a first table entry for each track is set to indicate that the state of the track is reliably KNOWN and a second entry is set to indicate that the track is virgin (unrecorded). Prior to a subsequent data access operation, the track table is copied from the media into a corresponding table in memory and each first entry in the media table is changed to indicate an UNKNOWN state. The memory track table is updated during the data access operations to reflect newly recorded or updated sectors. Upon completion of the data access, the media table is overwritten with the updated memory table.

Abstract: Each storage cell in an automated storage and retrieval system is provided with a mark, such as a bar code label, which is detectable to a vision system when the cell is empty. Further, each item storable in a cell is also provided with a mark, such as a bar code label uniquely identifying the item, which is detectable by the vision system. During an inventory of the contents of the system, the vision system is moved across the openings of the cells and scans for the marks. If an item mark is detected, entries in a data table are made indicating the location of the cell being scanned and its occupied status. The identity of the item detected can also be entered into the data table. On the other hand, if a cell mark is detected, entries in a data table are made indicating the location of the cell being scanned and its empty status. If neither mark is detected at a cell, additional steps can be initiated to determine the status of the cell.

Abstract: The present invention provides an apparatus and method for precise servo tracking of a multi-track magnetic tape head. The magnetic tape has at least one servo area with at least two servo tracks. Adjoining servo tracks have different servo patterns recorded thereon, one being a single frequency, constant amplitude signal, the other alternating between a zero amplitude null signal and a constant amplitude signal of a second frequency. A servo element in the tape head senses and combines the signals from both of the tracks. A detector outputs the peak-to-peak amplitude values of the combined signal and two register modules detect and store the maximum and minimum peak-to-peak values over a predetermined period of time. These maximum and minimum values are provided to a signal processor which determines their ratio.

Abstract: The present invention provides a method and an apparatus to accurately and consistently distinguish blank sectors from written sectors on optical media despite drive and media variations. A readback envelope threshold is established each time optical media is mounted into an optical drive. In one embodiment, the gain of readback amplifiers are set to a first level, the optical head seeks to and reads a sector or set of sectors on the optical disk known to have information recorded thereon and a first readback envelope generated. The gain off the readback preamplifier is then set to a second level, the optical head seeks to and reads another sector or set of sectors known to have information recorded thereon and a second readback envelope generated. The readback threshold is calculated from the amplitudes of the first and second envelopes.

Abstract: A method and system are provided for teaching a robotic accessor the actual location of the center of targets in an automated storage and retrieval system, the actual locations being different from expected or nominal locations due to tolerances in parts and assembly. A bar code scanner, which can also be used to read the identity of items stored in the system, is used to locate and scan each target and transmit to a controller a message containing the time during each sweep of the scanning beam when one side of the target is first detected and the time during each sweep when a second, opposing side is detected. The processor calculates the physical center of the target based upon the transmitted times from one or more sweeps. The coordinates of the center are then stored and later used to accurately locate and retrieve an item stored in the system. An optional calibration technique compensates for any angular offset in the bar code scanner.

Abstract: In an optical disk recorder, during the sensing of closely-spaced, position-indicating, machine-sensible indicia, a first peak of a track error signal is detected. In response to the first peak being detected, a half-track counter is decremented from a value which depends upon the position of the destination track relative to a current track. In response to the occurrence of a selected value of the half-track counter and the presence of a zero crossing of the tracking error signal, a first timer is activated to mask any defects occurring during the selected first half cycle of the last cycle of the tracking error signal. The half-track counter is again decremented in response to a second peak being detected and the occurrence of a next-to-last zero crossing of the tracking error signal and a second timer is then activated to mask any subsequent defects occurring during the second half cycle of the tracking error signal.

Abstract: A relative position error signal is calibrated in an optical storage device in which a tracking error signal (TES) varies as the light beam shifts its position through the objective lens. The calibration is performed by moving the coarse carriage to a predetermined region of the optical disk and measuring the TES. The fine actuator is adjusted until the tracking error signal equals a predetermined value. Then, the relative position error signal is read and an adjustment to the RPE gain is calculated to bring the gain to a predetermined value. The adjusted gain is used during normal disk access operations.

Abstract: An apparatus and method are provided for tracking the number of permanent and temporary errors, and spare sectors used as a result of the errors, on a per disk and per drive basis. During read/write operations, a determination is made as to whether the number of spares used to replace defective sectors on a disk, together with the number of spares used to replace defective sectors during formatting, exceeds a predetermined limit. This limit can be different depending upon the type of disk in use, rewritable or WORM. If the limit is exceeded, diagnostics are executed to ascertain the cause of the excess usage and appropriate corrective action, such as requesting that the disk and drive lens be cleaned, is initiated. Moreovers, an attempt can be made to recover used spare sectors on a rewritable disk.