Am International Incorporated

Don W Herrod

William R Swift

James Michael Marsh

A method of reading selected ones of an array of data frames from a microfiche medium substantially without errors attributable to misalignment of the frames. The method, which utilizes a microfiche reader-printer in adjusting for misalignment of the frames, includes the steps of determining the average distance between the frames along a first selected axis (e.g., the X-axis) of the array, and using said average distance in positioning the frames along the axis for reading. The frames are separated from each other by a predetermined nominal distance along the axis. The average distance is determined by dividing the distance between the outermost frames along the axis (the distance between the outermost frames being expressed in terms of the number of stepper motor steps needed to traverse said distance) by one less than the number of frames along said axis to produce a quotient, and adding the quotient to the predetermined nominal distance. A similar calculation of average distance between frames along a second selected axis (e.g., the Y-axis) is performed prior to positioning selected frames along said second axis for reading.

Method of correcting for misalignment of microfiche frames

The microfiche reader printer has multiple format capabilities. A lens support holding one lens for each format is slidable to position a lens into the light path. Positioning of the lens support closes or opens switches which direct a logic circuit to cause a controller to drive the microfiche holding platen in a certain manner dependent on the format. Copying utilizes a rotating xerographic drum. The platen is driven by stepper motors having a digitized sinusoidal input for microstepping drive for constant velocity drive during copying where the movements of the platen and the drum must be coordinated. The platen also takes a half frame back step before printing so that it can accelerate forward over the half step forward to reach constant velocity during scanning of the frame.

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Walnut, CA, United States of America

Don W Herrod