Abstract: The invention calculates the number of track crossing signals to be counted until a target position is reached without an actual seek operation, thus making it possible to complete a seek operation in a short time and without the need of the additional seek operation disclosed in the related art. A memory means is provided for storing the relation between the number of tracks (Delta t) from a current position to a target position and an indicator of the movement of said optical head toward said target position. A control means is provided for calculating the number of track crossing signals to be counted during a seek operation based on said stored relation when the target position is given, and for generating a control signal causing said optical head to seek based on the number of the calculated track crossing signals.

Abstract: A method for selecting data storage media for demount in an automated storage library, and an automated storage library and program product therefor are disclosed. Preemptive demount of storage media is permitted when all peripheral storage devices in the library are occupied and one or more of such devices remains inactive for a predetermined time. Storage media may be demounted to service existing mount requests, provide the peripheral storage devices in which the media are mounted are inactive. There is also a need, however, to ensure the availability of an empty device to service future mount requests, particularly in libraries having only a single gripper mechanism. Thus, even when no mount requests are pending, the status of the peripheral storage devices is continually monitored.

Abstract: A system for balancing the loads on channel paths in a digital computer during long running applications is disclosed. Only the load associated with relatively long running applications is monitored. For each volume of data eligible for processing, the selection of volumes is first made from those having affinity to the calling host. The load across the respective connected channel paths is calculated. The calculation is weighted to account for the different magnitudes of load resulting from different applications and to prefer the selection of volumes connected to the fewest unused channel paths such that processing of the selected volume will maintain the maximum number of unused channel paths. The optimal volume is selected as the next volume to be processed. The monitored load on each channel path is then updated to include the load associated with the newly selected volume, assuming that the load associated with processing the volume is distributed evenly across the respective connected channel paths.

Abstract: A data storage hierarchy which inherently allows for a level 1 storage file to be uniquely identified across an entire network is disclosed. A directory naming convention is employed which includes an internal identifier and a name for each subdivision of the network. Because each file can be uniquely identified across the network, a single level 1 storage space in a file space, or a directory therein, can be used for the entire network. Also, because of the inherent uniqueness of the naming system, common DASD control files otherwise required to map between level 1 storage files and their level 0 source files can be eliminated.

Abstract: Reliability of an automated storage library is improved by mounting at least one CCD cameras on a turret plate with two grippers, wherein the CCD camera provides video support for both grippers. The turret plate is rotatably mounted on the end of an anthropomorphic robot arm such that the camera and each gripper is rotated and angled into position as needed for viewing or gripping, respectively. The CCD camera is positioned to view a tape cartridge for capturing an image of the label attached thereto. While the captured image is being processed to verify the VOLSER, the first gripper is rotated into position and moved forward to grip the desired tape cartridge. The robot arm them moves the camera and gripper assembly to a tape drive and rotates the second gripper into position to remove another tape cartridge from the tape drive. The turret plate is again rotated to position the first gripper for inserting the verified tape cartridge into the tape drive.

Abstract: An apparatus for efficiently utilizing data recording media performs data compression beneath the level of the host processor is disclosed. To improve the ability of a recording media to be copied without increasing host processor overhead, the control unit which sees the compressed data is checked only upon recording a predetermined amount of uncompressed data. At such time, a compression ratio is calculated for the current data set and is used to monitor the recording of the remaining data of the current data set in compressed form. When a predetermined amount of compressed data is estimated to be recorded, the predetermined amount being the minimum storage capacity of a recording media, recording begins on a new recording media.

Abstract: An optical disk drive is disclosed in which sensing the position of a tilting prism driven by a fine tracking actuator uses the optical beam prior to its interaction with an optical disk. The optical beam emitted by a laser is redirected by the tilting prism. Most of the optical beam is reflected by the tilting prism in a direction through an objective lens for focused interaction with an optical disk. assuming a disk is mounted in the optical disk drive. The remainder of the optical beam is transmitted through the tilting prism, including any offset of the beam resulting from the refraction characteristics of the tilting prism, and received by a split far field detector. The split far field detector measures the offset of the optical beam which is a direct measure of the rotational position of the tilting prism. A relative position error signal is then generated and input to the coarse tracking actuator to coordinate its operation with that of the fine tracking actuator.

Abstract: This invention relates to a technique for obtaining a desired laser power. In write mode the laser power in an optical disk drive is determined in accordance with a DAC value which controls a power supply for the laser, but the correlation between the laser power and the DAC value significantly varies depending on the efficiency of the individual laser diode or laser oscillator. Because the laser power in read mode has been adjusted to a predetermined value during manufacturing, the DAC value which generates the same laser power as the reading laser power is known and is used to generate the desired laser power, such as the writing laser power.

Abstract: The current mode sample-and-hold circuit includes a differential amplifier having a non-inverting input coupled to a first leg of a current mirror from which a first current to be sampled is drawn. An inverting input of the differential amplifier is coupled to its output and further coupled to a capacitor through a sample hold switch. The first current drawn from the first leg of the current mirror causes the capacitor to charge, through the differential amplifier. The charged capacitor is coupled to the current mirror and biases the current mirror so as to provide the required first current. Opening the sample hold switch causes the capacitor to maintain a bias level determined by the first current. The bias signal in turn causes a mirrored current flowing in a second leg of the current mirror to be maintained, even in the absence of the first current. Thus an input current is sampled and a corresponding output current is provided. The capacitor operates in a feedback loop for improving accuracy.

Abstract: The invention is an optical disk drive which controls mechanical feedback to a focus servo actuator by shifting the phase of the feedback along its path back to the servo an additional 180 degrees to eliminate the degradation of the phase margin and prevent servo instability. The phase shift may be induced at any practical location along the feedback path. The phase shift is preferably induced by creating a slit or opening in the base of the optical disk drive. The opening must be positioned properly, shaped appropriately, and large enough to create a new base resonant frequency which prevents the opposite sides thereof from vibrating in phase. Alternatively, the phase shift may be induced by altering other components in the feedback path. For example, the phase shift can be induced by modifying the spindle motor assembly to create a new spindle resonant frequency.

Abstract: A data clock is synchronized to a modulation coded signal read from a moving storage medium by a phase error estimator circuit that samples the modulation coded signal two times on each side of a detected peak. A first detected data bit taken at a time N- 2 (two time periods prior to the detected peak) is used to predict the expected value of a first modulation coded signal sample taken at a time N- 1 (one time period prior to the detected peak). Similarly, a second detected data bit taken at a time N+ 2 is used to predict the expected value of a second modulation coded signal sample taken at a time N+ 1. Because the first and second detected data bits are able to predict the first and second samples, respectively, the phase error estimator circuit is able to accurately detect phase errors when sampling arbitrary data as would be presented by a (1,k) modulation coded signal. The expected values at times N- 1 and N+ 1 are compared to the actual values and error voltages are determined therefrom.

Abstract: A thin film magnetic head and a method for making the thin film head by the use of electrical lapping guides includes the use of a resistive lapping guide that has a height dimension and an electrical resistance that optimizes the results of the comparison of the resistive lapping guide to a finished lapping guide. The resistive lapping guide is not lapped during the lapping process. The finished lapping guide is lapped and the resistive comparison between the two determines the stopping of the lapping process. An as-lapped guide which is of the same dimensions as the finished lapping guide after lapping can also be included. An interleaved magnetic head having alternating magneto-resistive read elements and inductive write elements can be precisely lapped by sensing the resistance of the lapping guide elements and using a formula to determine the final resistance of the finished lapping guide to halt the lapping process.

Abstract: An interleaved head for reading and writing data transitions onto a magnetic tape. A magnetic recording system for the bi-directional transportation of the tape media across the interleaved head. A controller controls the tape drive in a reel-to-reel format to accomplish the bi-directional motion of the tape media. The interleaved head includes two modules with each module having a plurality of alternating read and write transducers alternately spaced apart along a single line placed transverse to the movement of the magnetic tape. The two modules are placed together such that the write gaps of one module are aligned with the read gaps of the other module. Each read module includes the magneto-resistive element. Each write transducer includes a thin film conductor driving a nickel zinc ferrite substrate as one pole piece and a nickel zinc closure piece as the second pole piece.

Abstract: Improved conversion efficiency and lower output ripple are achieved by a DC-to-DC converter that uses an H-bridge driver to alternately energize first and second inductors. By alternately energizing the first and second inductors, a higher switching frequency can be maintained allowing for the use of smaller inductors while reducing ripple in the output voltage. The reduced ripple in turn reduces the need for filtering. Additionally, the first and second inductors are wound about a common core such that a mutual inductance exists therebetween. The mutual inductance results in trapezoidal currents in each inductor instead of the typical sawtooth waveforms. This results in still lower ripple in the output voltage.

Abstract: A magneto-optic method and apparatus for recording digital data employs selective heating beyond the Curie or compensation temperature T.sub.c of the record material in the presence of an external magnetic field for recording information by rotating the direction of magnetization at the affected record locations, and the selective detection of the state of rotation of the polarization direction at information storage locations in a recording medium by way of analyzing the state of rotation of the light transmitted through said record material. The writing and retrieval of information are performed by means of a sharply pointed tip placed at an essentially constant distance above the recording medium, the sharpness of the apex of said tip determining the resolution and the achievable storage density. The heating of the storage locations is accomplished by means of a laser beam directed onto the recording medium through said slidably arranged tip.

Abstract: The invention is a positive peak level comparator for generating a positive peak pulse when a TES (Tracking Error Signal) is higher than a predetermined positive level, a negative peak level comparator for generating a negative peak pulse when the TES is lower than a predetermined negative level, and a logic circuit for generating an output pulse when said positive peak pulse and said negative peak pulse have been alternately input thereto. The arrangement prevents the TES from being miscounted even if the TES is distrubed due to the occurrence of, for example, a noise at a level close to either said predetermined positive level or said predetermined negative level and either said peak pulse or said negative pulse is successively generated.

Abstract: Locating and recognizing characters on a machine produced label, for example, is accomplished faster and more accurately by searching for first and second identifiable objects within first and second search windows, respectively. The first and second search windows are typically much smaller than the label or image being searched. The first object is the top portion of the label and the second object is the bottom portion of the label. Having located each object, a reference point is determined on each. From these two reference points, precise character or bar code locations can be predicted for reading the characters or bar codes printed on the label at predetermined locations. A character search window superimposed over each character at its estimated location is searched to read the character located thereat. If the first or second object could not be located, due to a torn label for example, an alternate object may be searched and a reference point located thereon.

Abstract: A method for selecting additional data storage media for demount in an idle automated storage library, and an automated storage library and program product therefor are disclosed. The method permits the advanced demount of storage media when one or more of the occupied peripheral storage devices remains inactive for a relatively long predetermined time. Storage media may be demounted to service a pending mount request, provided the peripheral storage devices in which the media are mounted are inactive. A storage medium may also be demounted to create an unoccupied peripheral storage device, even though no mount request is pending, when all of the peripheral storage devices are occupied and one or more of such devices remains inactive for a relatively short predetermined time.