International Business Machines Corporation

Nelson K Arter

William C Dodt

Howard C Jackson

Thomas F Eichhorn

Clement H Kalthoff

Marion J Herman

George W Brock

Michael A Bartholet

Michael D Avritt

Francis E Hauke

Mark G Call

Charles A Farel

William George Jackson

Marvin Edward Prahl

Mark L Rhoades

Arthur B Wills

Dennis C Estabrooks

Ernest William Devore

Leslie R Zelenka

Jesse A Weber

James Warren Leggate

Roger D Emeigh

Clarence Howard Hammond

Daniel James Pedersen

Error compensation in a feedback servo system. The feedback servo loop in, for example, a head positioning circuit in an optical disk data recording and retrieval system is provided with a compensation signal to correct for misalignment or other errors. The head in such a system must be dynamically maintained at a best focus position but, through use and transporting, the alignment of the head position error detecting system can be disturbed. In some cases, the loop circuit parameters may drift from their original values. To correct for errors introduced from such causes, the head is positioned at best focus and the focus error (head position error) signal is sensed. A correction signal is supplied which cancels out the sensed value while the system is operating.

Focus servo loop off-set compensation

A document feeder for automatically inverting a duplexed original so that the second side may be copied. The inverting mechanism is a turnaround roll located at the exit of the copy station. The inverting mechanism cooperates with rollers located above the document glass for moving documents thereacross. The rollers are inclined at an angle to the direction of paper movement in order to position paper against a side reference edge. When receiving a document from the turnaround roll and moving it in the reverse direction, the inclination of the rollers is removed or altered to a minus angle. Alternatively, a second set of rollers, inclined at a minus angle, are brought into active use when documents are moved in the reverse direction.

Automatic duplex document feeder

A stapler mechanism for fastening variable thickness documents includes a stack receiving receptacle disposed between the head/hammer assembly and the clinching or anvil assembly of said stapler. A sensing device is coupled to the stapler mechanism and generates control pulses indicative of relative motion between the head/hammer assembly. A controller processes the signals and generates control signals which vary the stroke and the force driving the hammer and returns the head/hammer assembly to its home position following a stapling cycle.

Variable thickness set compensation for stapler

In a machine having a reciprocating original document handling carriage such as a copier, a selectively operable roller is positioned for removing documents from the upper surface of the carriage. The roller is driven by movement of the carriage by power stored from carriage movement or by an independent power source. Continuously driven rollers are positionable in coordination with the end of a run of copies for a given document to eject the document onto an output tray as the carriage returns.

Document ejector apparatus and method useful for copiers

In a machine having a reciprocating original document handling carriage such as a copier, a roller at the bottom of a sloped ramp rests on the upper surface of the carriage. Documents placed on the ramp slide downward until the leading edge is at the nip between the roller and carriage surface. Movement of the carriage pulls the document from the tray onto the carriage surface for scanning. An additional roller can be included to provide automatic document ejection by pushing the document onto an output tray as the carriage returns.

Document feeder for moving bed machines such as copiers

A forward/backward compatible apparatus and record member achieves multiple density by multiple track widths as well as multiple lineal densities. In a rotating head recorder a single head has a wide write gap followed by a plurality of narrow read gaps. In recording, narrower tracks--i.e., higher densities, the record medium is moved less than the width of the write gap for recording narrower tracks. The narrower tracks have the same width as the trailing read gaps. During readback, all read gaps are simultaneously operative. Signals from one of the read gaps are processed immediately, while signals from the remaining read gaps are buffered until a dead time occurs, such signals are then processed. The same principles are applicable to magnetic card and magnetic disk recorders. A record member of the disclosure employs a table of contents area always recorded at the lower density--i.e., widest track. The table of contents contains indicia indicating the track density as well as the lineal density of the other recording areas. The buffering also is employed to overlap seeks in a disk file for greater data accessibility.

Buffered recording

In a helically scanned device, a length of flexible media, with transverse data tracks thereon, is positioned relative to a rotating transducer. The transducer coacts with the media to transduce data therefrom. The transducer is coupled to a piezoelectric bender. Periodically, the instantaneous position of the transducer is monitored and an error signal is generated. The error signal is used to drive the piezoelectric bender so that the transducer follows the data track.

Stripe following in a helical scan device

During a search operation in a rotating magnetic head tape transport, the tape is transported from a supply spool via guides and a vacuum column past the rotating head read/write station to a take-up spool. As the tape is wound onto the take-up spool in layer-by-layer convolutions, air is entrapped between the layers. The entrapped air forms a layer of air film and as a result the tape is loosely wound on the take-up spool. A 'Hard Step' voltage is generated and is applied to the capstan motor at the end of the search operation to tighten any loose wraps caused by the air entrapment during the search.

Procedure for tightening tape wraps on a spindle

In a rotating head magnetic tape transport, the tape is maintained stationary as the head sweeps a selected data track. A length of tape is buffered in a vacuum column between a supply spool and a rotating head station. A take-up spool on the opposite side of the head station is controlled by minimizing the overshoot or undershoot of the motor driving the take-up spool as the radius of the amount of tape on the spool increases or decreases (i.e., change). After a step operation, the overshoot or undershoot of the motor is measured and compared with a reference range to determine if the undershoot or overshoot is within the reference range. If the measured quantity is within the reference range, no adjustment is made. If the measured quantity is outside of the voltage level or reference range, the gain of the take-up motor is adjusted.

Adaptive voltage control of motor in an incrementing magnetic tape

An elongated magnetic tape has a pair of longitudinally extending servo track areas, one of which is closer to the longitudinal center of the tape than the other. The lateral space intermediate the servo areas receives data signals, while the space between said one servo area and one edge contains identification and address signals. The tape is particularly adapted for use with rotating head recorders having two gaps on the rotor, with an intergap distance slightly greater than the lateral extent of the servo areas. A recording or write gap precedes an immediately trailing reading or recovery gap. When the rotor gaps pass the one edge in the one servo area, the write gap senses the servo track; while the read gap senses the identification signals. The arrangement is such that prior to the time the write gap reaches the data recording area, the read gap has sensed the identification signals. In a similar manner, when the gaps are leaving the data signal area, the write gap is sensing the other servo area; while the read gap is still sensing data. The longitudinal extent of the servo areas indicates, respectively, beginning of tape (BOT) and end of tape (EOT). A leader portion includes a magnetic coating for facilitating calibrating magnetic recording apparatus to each particular article.

Rotary head magnetic recorder for use with a specific record member

Magnetic record member for use with rotating head magnetic recording

A track or stripe tape positioner for a helical scan or rotary head recorder uses digital techniques. The expected step size is preset into a counter. During the next phase, a calibration phase, the tape is stepped through a plurality of stripes whereat the preset value is adjusted to measured values. In the third phase, the average step size is maintained subject to certain averaged changes thus providing a high degree of noise rejection to ensure reliable incremental stepping of a record tape through the recorder.

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Longmont, CO, United States of America

Nelson K Arter