Storage Technology Corporation

International Business Machines Corporation

John Paul Mantey

Steven Gregory Trabert

Ronald Dean Gillingham

Richard Lewis O'Day

Donovan M Janssen

James C Cates

Keith Gary Boyer

James A Valent

Donald F Colglazier

Richard H Dee

Mark A Beran

Lance A Walker

William H Ashbee

Donald C Roller

Ronald J Martin

Larry E Rittenhouse

Gerald P Patch

Positioning of a tape head relative to a magnetic tape may be improved through accurate measuring of magnetic tape position error. The tape head includes at least one read module having two servo read elements. A head control detects the presence of corresponding synchronization fields passing the servo read elements. The elapsed time between the detected synchronization fields is determined. Tape skew is calculated based on the elapsed time. Tape position error calculation may be further improved by including another servo read element on either a second read module or a write module. Tracking information read from two servo read elements scanning the same servo stripe is used to calculate the offset between a read module and the write module.

Measurement of tape position error

A servo track writer head writes servo tracks on a data storage tape with increased accuracy. The servo track writer head includes a leading writer for each servo track. Each leading writer writes a synchronization field on the tape. The servo track writer head also includes a sequence of trailing writers for each servo track. Each trailing writer produces at least one trailing field on the tape a fixed distance behind the synchronization field. The servo track writer head also includes one timing writer. Each timing writer writes a timing field on the tape at a timing distance in the tape direction from each of the synchronization fields. The servo track writer head also includes a sequence of timing readers corresponding to each timing writer. The number of timing readers in the sequence is equal to the number of trailing writers in the sequence of trailing writers. Each timing reader reads the timing field on the tape written by the corresponding timing writer and generates a signal used to initiate writing of corresponding trailing fields. The positioning of timing readers permits the appropriate fixed distance behind synchronization fields for writing trailing fields to be determined.

Tape head with pattern timing for servo writing application

A method for writing a servo pattern onto a length of magnetic tape includes writing a first frequency signal onto a first portion along the length of the tape, and writing a second frequency signal by simultaneously writing a plurality of spaced apart predetermined shapes. The predetermined spaced apart shapes are achieved by writing the second frequency using a writer having a split top pole. Passing the tape over the spaced apart top pole elements allows the writer to simultaneously write the plurality of spaced apart shapes. The tape can then be passed over a read module.

Method for writing a servo pattern using a writer having a split top pole

A servo stripe pattern for determining the longitudinal position of the tape with respect to the tape head. A data field on each frame of the servo pattern includes a digital one or a zero. An adjacent series of data fields are arranged in a predetermined sequence defining synchronization and position count fields. The position count field allows the tape controller to accurately determine where, along the length of the tape, the tape head is currently positioned.

Tape servo pattern having an embedded position count field

A magnetic tape servo pattern with different frequency signals to define the frame boundary. A significantly different frequency field is used to signal the transition from one frame to the next.

Tape servo pattern with enhanced synchronization properties

A magnetic tape servo pattern including track identification. Information from a track identification area intersecting one or more tracks on each frame in combination with information identifying the track as odd or even, is used to uniquely identify the track.

Tape servo pattern with embedded servo track number identification

A method for detecting a frame edge in a servo stripe on a length of magnetic tape. The method includes converting an analog signal to a digital signal and detecting a change in digital signal frequency at a frame edge. A detection signal is generated in response to the detected frequency change.

Servo frame edge detection for tape servo pattern with synchronization

A thin film magnetic tape head including a split top pole. The split top pole configuration allows multiple patterns to be written simultaneously onto a servo band.

Thin film tape head including split top pole

A method for identifyng a servo track. Information from the servo track about the odd or even number of the track is combined with information about the presence or absence of a track identification area to identify the track number.

Method for servo track identification

A method for determining the longitudinal position of a length of magnetic tape with respect to the tape head. A data field on each frame of the servo stripe includes a digital one or a zero. An adjacent series of data fields are arranged in a predetermined sequence defining synchronization and position count fields. Identifying the position count field allows the tape controller to accurately determine where, along the length of the tape, the tape head is currently positioned.

Method for determining longitudinal position on a magnetic tape having

A servo-controlled recirculating automatic document feeder (RADF) includes a plurality of independently driven document transport devices. A picker mechanism separates documents in seriatim from a stack. An entry turnaround transport device buffers and delivers picked documents to a platen transport device for exposure. After exposure, the document is transported along a simplex or duplex path for duplex or simplex copying. The document is then buffered in an exit turnaround transport device and is subsequently returned to the stack. Each transport device is independently driven by a motor and a closed-loop servo. A common reference oscillator generates source signals for the servo-loops. A microcomputer operates on the source signals and generates reference signals for driving the transport devices.

Servo-controlled automatic document feeder

A sheet registration apparatus for positioning sheets in a registered position on a work surface such as the document platen of a convenience copier/duplicator machine. The apparatus includes a bidirectional servo-controlled sheet transport for conveying the sheet over the work surface. A sheet sensing device is disposed within the path of sheet travel. A controller monitors the sensing device and activates a position control routine following the occurrence of a predetermined level change in the signal generated by the sensing device. At the end of the position control routine, the transport is stopped thereby positioning the sheet in the registration zone. The apparatus enables sheet registration for a machine operating in a duplex and/or simplex mode. The apparatus further enables registration at any point on the document platen.

Document feeder electronic registration gate

A device for feeding sheets from a supply station aligning the sheets in an X, Y and .theta. coordinates and then gating the sheet into a work station such as the transfer station of a copier. The device includes a pair of independently servo-controlled motors disposed on opposite sides of the sheet. Each motor drives a nip roller which transports the copy sheet. Sensors are disposed to generate signals representative of sheet position in the X, Y and .theta. coordinates. A controller uses the signals to adjust the angular velocity of the motor so that the sheet is squared and is gated onto the work station. The sensors and controller are utilized to measure different parameters associated with the sheet.

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Boulder, CO, United States of America

John Paul Mantey