R-byte, Inc.

David R Lee

Theodore D Rees

Edward J Rhodes

Ta-Lin Chang

Clifford R Berry

Daryl K Adams

Horatio H Lo

An automatic track follower (ATF) system for accurately positioning the read/write head on the tracks of a magnetic tape comprises a pilot signal generator for generating pilot signals from tape pilot marks; a sample-and-hold circuit for sampling the pilot signals from the tracks immediately adjacent a track being read; a comparator for comparing the magnitudes of the pilot signals from adjacent tracks on both sides of the track being read; a correction circuit for centering the read/write head on the track being read; and a processor for digitally controlling the generator, sample-and-hold circuit, comparator, and correction circuit and their functions, the digital control being under programmable control. Three code bit fields are discriminated from the digital data to detect the beginning of the ATF field on the tape to derive the ATF logic, timing, and control functions.

Digital data tape storage automatic track follower system

In a digital data storage audio tape system having a host device interface unit, a main data buffer manager, a main data buffer, a processor, a data separator, a tape drive unit, and a read/write channel, this invention comprises a formatter providing track construction, encoding and decoding, error correction, and direct memory access of digital data transmitted between the host device unit and the tape drive unit and a frame buffer for buffering digital data for encoding and decoding, and error correction. The formatter is coupled between the main data buffer manager, via a direct memory access channel, and the read/write channel of the tape drive, and further is coupled to the frame buffer. The formatter is coupled to and responsive to instruction control by the processor in conjunction with instruction control of the tape drive unit by the processor.

Digital data storage tape formatter

This invention is a beginning-of-tape/end-of-tape detection apparatus and method for use in a tape drive system having supply reel, take-up reel, and capstan motion sensors. The invention comprises monitoring means for monitoring each of the angular position signals and processor means for computing beginning-of-tape and end-of-tape utilizing the varying diameters of the supply reel and its tape pack and the take-up reel and its tape pack, and angular velocities of the reels and capstan. This invention provides a plurality of systems and methods for BOT/EOT detection with selectable tolerance levels. These include coarser detection without capstan engagement of tape (for use in high-speed spacing operations), finer detection utilizing capstan engagement, and absolute BOT/EOT detection utilizing the physical ends of the tape. This invention has the advantage of accurately determining beginning and end of tape without requiring special detectors.

Beginning/end of tape detection system

This invention is an improved digital data storage magnetic tape transport servo-control system comprising a tape supply reel and supply reel motor, a tension transducer, a head drum having at least one read/write head secured thereto and coupled to a head drum motor, a capstan and a capstan motor, a pinch roller, a take-up reel and a take-up reel motor. A processor provides programmable digital control signals to and responsive to signals from the supply reel, the supply reel motor, the tension transducer, the head drum, the head drum motor, the capstan, the capstan motor, the take-up reel, and the take-up reel motor. The processor controls tape tension in cooperation with the supply reel motor and the tension transducer, controls tape speed in cooperation with the capstan and the capstan motor, controls take-up reel torque in cooperation with the take-up reel and the take-up reel motor, and controls head drum speed in cooperation with the head drum and the head drum motor.

Digital data storage magnetic tape system comprising a single chip

This invention is a method and apparatus for the automatic calibration of the magnetic head offset angles in a helical scan rotating head drum and the generation of idealized track timing for recording and reading magnetic tape. A calibration tape is used to provide calibration marks and in conjunction with pulse generator (PG) encoder and frequency generator (FG) encoder signals, a processor calculates the offset angles. The offset is calculated from the time an FG signal edge occurs until the time of detection of a calibration feature. For a read head calibration, this provides a rough calibration of the angular location of the read head on the head drum. Using this rough calibration, data is read from the calibration tape, including the measured longitudinal position of the calibration feature. An accurate calibration of the angular location of the read head is then calculated. For the write head, tracks are written on a blank sector of the calibration tape, using the known relative angular location of the read head, an accurate calibration of the angular location of the write head (which just wrote the track) is thereby provided. The same circuitry can also generate track timing signals based on the edges of the FG signal.

Automatic helical scan head drum calibration and track timing generation

An apparatus and method for the commutation of a brushless dc motor having a rotor and a plurality of coils, and an encoder generating quadrature signals responsive to the rotation of the rotor. The commutation apparatus comprises a commutation control device, coupled to the encoder, for controlling the sequence of motor coil energization utilizing the quadrature signals. The commutation method utilizes the quadrature signals for composite signal generation, rotor rotational direction and position to achieve precise commutation. Precision commutation is achieved without the need for any additional commutation sensing devices.

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San Jose, CA, United States of America

David R Lee