Data Products Corporation

John K Ham

Richard A Strissel

Sultan W Khan

Doina Mazilu

Paul O Amdahl

Commencing with the first print hammer(s) 'out', or actuated, on each print line the hammer drive current is boosted 10% for a period, ranging from 25%=650 microseconds for single part forms to 50% for multi-part forms, of the total print hammer flight time. Earlier striking hammers on each print line strike harder, alleviating displaced first-printed characters on single part forms and light characters on multipart forms due to hammer energy loss in forms compression.

Uniform print density and registration in an impact printer

A self-diagnostic printer controller circuit and system may be fabricated in an inexpensive and flexible manner by functionally dividing the tasks of the printer system into separate modules which are intercommunicated through a plurality of buses on a mother board. One of the modules is a central processing unit particularly adapted to performing the required operations in a printer system. The printer system may contain a plurality of additional options, one of which is an internal vertical format unit in which paper instructions may be stored and selectively retrieved by the central processor unit to be used as data to direct the operation of the other modules according to the selected format. The printer has a stepper motor for vertically advancing a printing medium being printed and the VFU includes a format memory for storing information establishing the desired format for printing onto the medium. Vertical advance control means, connected to the stepper motor and to the format memory, are included for accessing vertical format information from the format memory and for causing the stepper motor to advance the medium vertically by a distance established by the accessed information. The VFU also includes circuitry, responsive to a 'direct access' command received from the external data source, for loading into the format memory new vertical format information supplied from the external data source.

Microprogrammable processor control printer system

A self-diagnostic printer system divides tasks of the printer system into separate modules using a plurality of buses on a mother board. A central processing unit module performs the required operations in the system. An interface module interfaces the central processing module with a digital system user, a tape input, and an operator through a control panel. A timing and status module monitors a plurality of printer device fault conditions, generates a plurality of enable signals and drive signals and interfaces timing signals from a printer to the central processor unit. A power module generates driving currents for a clamping solenoid and a stepper motor so as to move the paper through the printer. A hammer driver module selectively fires hammer driver circuits to generate hard copy printout of digital information. An internal vertical format unit in which paper instructions are stored and selectively retrieved is used to direct the operation of the other modules according to a selected format. A detailed error, status and diagnostic scheme may be selectively executed at any point within the printer operation during any of the printer system's modes of operation, to provide visual output to the operator indicating an error or a status, and the nature and location of the error or type of status which has occurred so that any error within data or printer operation can be instantly analyzed and isolated to permit convenient rectification.

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Simi, CA, United States of America

John K Ham