Abstract: A record carrier having essentially circular tracks concentrically located around a point of rotation. The record carrier is divided into circular zones each having m tracks, where m is an integer. Each track within a zone is subdivided into n sectors, where n is an integer which is constant per zone and which increases as the zone is more remote from the point of rotation. Each sector including a header portion and a data portion. The header portions in the radial direction in each zone are in line. In each zone the condition of m*n=j*k is satisfied, where is j an integer greater than or equal to 2 and is constant for each zone, and k is an integer.

Abstract: The present invention is intended to provide a method for putting an optical head in a stationary state, and an optical disk drive apparatus for doing so without the need of a dedicated sensor for detecting an absolute position of the optical head in the radial direction of the optical disk or a device for fixing the head.

Abstract: A system is provided for monitoring signals transmitted over one or more optical serial interface channels in an ESCON environment. A formatter card mounts on bus connector in a general purpose tracing tool (GPT) and intercepts optical I/O signals being transmitted between a host processor and, a peripheral device. The signals are decoded into trace data words which are then partitioned into ESCON transaction frames and mapped into a block of GPT frames. The GPT block is stored on the formatter card and transmitted to the GPT when the GPT can accept the data. Data received by the GPT is interleaved with data from other formatter cards attached to other I/O channels (both ESCON and non-ESCON) and is displayed or printed in time-correlated format for analysis. Data can also be stored for later review.

Abstract: An optical disk drive apparatus operable under track following mode and seek mode wherein, upon the detection of a track following operation error, a seek operation is initiated for seeking a new target track at a predetermined number of tracks distant from the current track. The seek operation is controlled to follow a velocity profile thus regaining control over an optical head that may have been jolted into an out of control velocity when the track following error occurred. The velocity profile provides for a reduced velocity as the target track is approached. The new target track is selected at a relatively large number of tracks distant from the current track if the head velocity is high and at a relatively small number of current tracks if the head velocity is low. If the current track is sensed to be an outer track, the new target track is selected toward the inner track and if the current track is sensed to be an inner track, the new target track is selected to be an outer track.

Abstract: The present invention provides an apparatus and method for sensing the contamination level in an optical storage device and for issuing a signal when the contamination exceeds a predetermined value relative to a base value. The tracking error signal gain of an optical drive is monitored and compared with a base gain. An alert signal is then generated if the actual measured gain exceeds a predetermined level relative to the base gain, whereupon a cleaning device can be mounted in the storage device and optical elements cleaned.

Abstract: Apparatus and method are provided to increase the capacity of spiral track data storage disks while improving the reliability of access to sectors on the disk by permitting previously unusable sectors immediately following a band boundary to be reliably accessed. In accordance with the present invention, an optical drive controller is provided having a clock for generating a clock signal with a frequency of f.sub.N and a cycle slipper for generating a slipped clock signal with a frequency of f.sub.N-1 from the clock signal. The controller also includes a device for enabling the slipper when an optical head is positioned opposite a sector in a band N-1 during a seek operation to a target sector in band N, and for disabling the slipper when the optical head is positioned opposite the end of the last sector in band N-1. Thus, identification information pertaining to sectors in band N-1 is processed at a data transfer rate of f.sub.N-1 and the data transfer rate is switched to f.sub.

Abstract: An optical disk drive includes a gain control for controlling the gain of a focus servo loop in response to the seek velocity of an optical head. At a low seek velocity, the focus servo gain is reduced to minimize the influence of beam scattering on the groove of an optical disk onto a focusing error signal (FES) and a tracking error signal (TES).

Abstract: A method and system for locating and predicting synchronization characters within data blocks stored within multiple tracks on a removable data storage medium in a data storage system. The location and identity of each diverse synchronization character within multiple data blocks is predicted in response to an identification of an initial acquisition character and an identification of a particular data storage format. A first synchronization character is predicted and a synchronization counter is then incremented in response to a detection of each subsequent synchronization character, or, in response to the elapse of one of two predetermined delay periods. A system clock delay period is initiated immediately after each synchronization character is detected and the synchronization counter is then incremented at the end of that delay period. A second delay period is initiated thereafter, utilizing a derived track clock signal, which is reasonably insensitive to variations in storage media transport speed.

Abstract: An actuator assembly is provided for controlling the position of a multi-track, magneto-resistive transducer to index across tracks in a track seek mode and to rapidly adjust the position of the transducer in a servo controlled track following mode. The actuator includes a base, a beam spaced from the base and movable relative thereto, opposing upper and lower flexures in parallel planes connecting upper and lower portions of the base with upper and lower ends, respectively, of the beam, and an electromagnetic drive means. Each flexure comprises a constraining member fastened to and substantially covering a plate. The constraining member has a plurality of voids formed therein. In one embodiment, the voids comprise parallel openings extending through the constraining member; in another embodiment, the voids define a honeycomb structure; in still another embodiment, the voids define a corrugated structure.

Abstract: A method and system for accurately reading and storing data as multiple data blocks on a removable data storage medium mounted within a data storage system. Each data block includes an initial acquisition data character and multiple diverse synchronization characters/bursts and adjacent data blocks are separated by a unique interblock gap character. A multimodal interblock gap character detection circuit is provided which may operate in a normal mode of operation or a stringent mode of operation, wherein an enhanced degree of certainty is required for detection of the interblock gap character. A predicted time window of occurrence for a next interblock gap character is generated in response to detection of an initial acquisition data character and at least one synchronization character within a data block. Additionally, a global clock count signal based upon multiple track outputs is generated each time a resynchronization burst is encountered.

Abstract: A method and system for detecting and validating multibit acquisition burst sequences which precede and follow each data block in a multitrack data storage system. An acquisition sequence pattern detection circuit is utilized to provide an indication of acquisition burst sequence detection in response to an occurrence of an accurate sequence of a selected number of acquisition burst sequence bits. A latch is utilized to store the pattern criteria indication for each associated track and the latch outputs are then combined in a logic circuit to provide a composite burst pattern error indication signal.

Abstract: An envelope follower is provided which reduces defect propagation when reading analog information signals from a read head of, for example, an optical drive or a magneto-resistive tape drive. In a preferred embodiment, the envelope follower includes a differential amplifier, to sense the difference between the amplitude of the information signal and an envelope voltage across a capacitor, and a current mirror, responsive to the differential amplifier, to charge the capacitor at a predetermined rate when the amplitude of the information signal exceeds the envelope voltage. When the amplitude of the information signal is below the envelope voltage, the current mirror is deactivated by the differential amplifier and the capacitor is allowed to discharge through a voltage divider.

Abstract: Two identical CRC circuits are cross coupled to make alternate CRC calculations based on the other CRC circuit's calculation. Throughput of the CRC code calculation is improved by applying alternate input data simultaneously at each of the CRC circuits so that when one calculation is completed the next input data is available to immediately begin the next calculation. The output of each CRC circuit is fed into one of two latches that make up an LSSD register such that the first latch captures the first CRC calculation on a first clock of non-overlapping clocks. The second CRC calculation is captured by the second latch on a second clock of the non-overlapping clocks. Two CRC calculations can be made in one period of the non-overlapping clocks while avoiding race problems.

Abstract: A track access apparatus is provided by the present invention in which a reference drive signal 90 proportional to the reference acceleration of a beam spot 22 is generated according to the contents of a track counter 34. A signal 92 indicating the reference velocity of the beam spot 22 is generated by an integrator 40 in accordance with reference drive signal 90. A signal 82 indicating the position of an objective lens 20 relative to a coarse actuator 26, a signal 84 indicating a relative velocity, and a signal 94 indicating the difference between the actual velocity of beam spot 22 and a reference velocity are supplied to coarse actuator 26 and to a fine actuator 28. Reference drive signal 90 is supplied to coarse actuator 26. The present invention makes maximum use of the rapid acceleration and deceleration capability of the coarse actuator and moves the beam spot to a target track accurately at high speed.

Abstract: Apparatus and method are provided to increase the capacity of spiral track data storage disks while improving the reliability of access to sectors on the disk. In one embodiment, employed when logical tracks on an optical disk are grouped into concentric bands, previously unusable sectors immediately following a band boundary can be reliably accessed. In accordance with this embodiment, when the target sector is, for example, the first sector of band N and a laser beam from a read head lands on a sector in the previous band N-1, the clock governing the data transfer rate is set to the frequency of the band N-1 and a sector in that band is detected and identified. Based upon the period of sectors in the band N-1, a delay interval is computed which ends when the last sector in the band N-1 rotates past the laser beam. Sector mark detection is disabled during the delay interval and the clock frequency changed to that of band N.

Abstract: A method and apparatus are provided for biasing a non-center tapped magneto-resistive head at a constant voltage using two separate biasing stages to provide independent control over the voltage at each of the two terminals of the head. A first control device detects the voltage at a first head terminal and directs changes to the output of a current source, interconnected with a first terminal of the head, to maintain the voltage at the first terminal at a first predetermined voltage. A second control device detects the voltage at second terminal of the head and directs changes to the input of a current sink, interconnected with the second terminal, to maintain the voltage at the second terminal at a second predetermined voltage. Each control device is interconnected to a separate reference voltage source; by appropriate selection of the voltages of the reference voltage sources, the voltages at the two head terminals and the potential across the head can be established and maintained.

Abstract: A tape path having an implicit squeeze bearing. In such a tape path, one end of the tape is wound upon a first reel, the tape extends around one or more guides, briefly comes into close proximity with itself at the outer wrap of the tape wound upon the first reel, and is wound upon a second reel. By coming within close proximity with itself, the tape forms an implicit squeeze bearing which damps tape tension variation, inhibits the transmission of vibrations from one reel to the other, and eliminates the entrapment of entrained air without any additional rollers or other components. The tape path is suitable for use in a peripheral storage device, such as a magnetic tape drive, and is compatible with a variety of tape cartridge configurations.

Abstract: A power amplifier supplies substantial load currents that must be accurately monitored to provide feedback so that the load currents can be properly controlled. A sense current is generated from a load current that is scaled such that the sense current is an accurate representation of the load current but having a substantially smaller magnitude. The scaled sense current is generated by coupling a power sense resistor to a pilot sense resistor by a voltage follower. The power sense resistor is in series with the load current and develops a load voltage thereacross. A sense voltage, being substantially equal to the load voltage is impressed at the pilot sense resistor by the voltage follower. The pilot sense resistor is some predetermined ratio of the power sense resistor so that absolute values are not critical. The sense current flowing through the pilot sense resistor is therefore scaled according to the ratios of the power and pilot sense resistors.

Abstract: An on-chip apparatus and method are provided for automatically tuning a continuous time filter in which a single filter selectively filters an information signal or, when tuning is desired, an unfiltered reference signal. During tuning, a controller determines the amplitudes of the unfiltered and filtered reference signals and their ratio. From the ratio, the controller ascertains a corresponding center or tuned frequency of the filter. If the ascertained frequency does not substantially equal a desired tuned frequency, the controller directs a bias controller to adjust the bias of the filter until the tuned frequency is substantially equal to the desired tuned frequency.