International Business Machines Corporation

William H Ashbee

Donovan M Janssen

James A Valent

Larry E Rittenhouse

Ronald J Martin

Mark A Beran

John Paul Mantey

Donald F Colglazier

William S Seaward

Alan J Kirton

Richard S Kilen

Gerald P Patch

An apparatus and method are disclosed for positioning magnetic heads relative to the recording tracks of a recording medium such as a floppy disk having circular, concentric recording tracks formed thereon. The magnetic heads are mounted on a head carriage, and the head carriage is moved, in response to received command pulses, so that the heads are moved linearly, by step increments, along a radius of the floppy disk. The heads are thereby moved across the spaced tracks on the disk, with each incremental movement of the heads being a distance less than the distance between the tracks, and being, for example, one-half or one-fourth of the total distance between tracks. Acoustic noise due to head movement is minimized by moving the heads by increments less than the distance between the tracks, with such movement avoiding exciting the resonances of the head moving apparatus. The magnetic heads are initially moved at a rate known to avoid exciting the resonance and, during such initial movement, the rate of received command pulses is determined. If the received command pulse rate is within a predetermined range, and is a rate that will not excite resonance, continued movement of the head is at the rate of the received command pulses.

Magnetic head positioning apparatus and method

Electronic alignment of paper feeding components in a machine such as an electrophotographic copier machine is achieved by placing an original master containing vernier calibrations on the document glass and a target master containing vernier calibrations in the copy paper bin. Thereupon, the machine is operated to produce a copy of the original master onto the target master producing a double set of vernier calibrations on the target master, which, when compared, provides information relating to skew angle, side edge relationship and leading edge alignment of the image to the copy paper. The vernier calibrations provide data which are keyed into a microprocessor controlled copy feeding servo mechanism to correct copy paper position and remove misalignment. The operation is repeated for various combinations of paper feed paths with techniques of original document placement and for duplex operation so that the copy paper matches image position for all modes of copier operation. For printer mode of operation, the master vernier is printed to produce the needed image. In addition, sensors are located in the copy paper path to automatically correct for deviations in the copy sheet feeding unit, caused by wear, for example, over a period of time. Sensors are also located in the document feeder so that corrections in the position of the copy paper may be made on an individualized and dynamic basis to electronically correct for misalignment of individual originals on the document glass.

Electronic alignment for a paper processing machine

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 hardware counter counts high rate, lower significant bits. A carry-borrow circuit responsive to the higher order bit position of the hardware counter includes cancel means responsive to successively received carry and borrow signals to cancel previously generated carries or borrows. Memory means in the carry-borrow circuit memorize the generation of the carry or borrow by the hardware counter. A programmed microprocessor, or the like, periodically senses the status of the carry-borrow circuit for transferring signal contents thereof to a software controlled count field. The arrangement permits high speed counting without interrupting the microprocessor and not imposing rate constraints on program execution of the microprocessor.

Hardware-software counting

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Boulder, CO, United States of America

William H Ashbee