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US 4,226,546 AGranted
Printer control system
AssigneeSCI Systems, Inc.
InventorMark H. Hoffman
Life of this patent
Estimating the term…
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AssigneeSCI Systems, Inc.
InventorMark H. Hoffman
Estimating the term…
The intermittent movement of the printer's carriage and "daisy"-type print wheel is controlled by a relatively simple, reliable digital control system. The difference between the desired velocity and the actual velocity of each member is measured digitally. This difference constitutes an error signal which is used to retrieve stored values of acceleration or deceleration corresponding to various values of the error signal. These values are used to develop a corresponding electrical signal which is used to accelerate or decelerate the member to reach the desired velocity. A relatively simple circuit is provided for reliably returning the carriage or print wheel to a desired position after overshooting the position, despite a relatively large amount of overshoot. Simple, low-power-consumption holding or drive circuits utilizing pulsed voltages are provided for the stepping motors used for ribbon feed and line feed, and for the solenoids used for ribbon shift, print wheel shift and print hammer energization. Digital control of the print hammer intensity is provided by controlling the duty cycle of the hammer energization signals in accordance with intensity values stored in memory.
In a printer having a printing element movable to a printing position by means of a printing element drive means, control means for controlling said drive means to move said element from a first position to a second position, error signal means for comparing the actual instantaneous velocity of said element with a signal which indicates the desired instantaneous velocity of said printing element during its movement from said first position to said second position and developing an error signal corresponding to the difference between said velocities, a digital data storage unit for storing values of acceleration corresponding to said error signals, and means for energizing said drive means with drive signals corresponding to said values.
A device for controlling the velocity of a driven member, said device comprising means for indicating the present velocity of said member, means for indicating the desired velocity of said member, data storage means for storing values of acceleration corresponding to various values of the difference between said velocities in order to change the present velocity to said desired velocity during a predetermined period of time, and means for delivering signals corresponding to selected ones of said values of acceleration to a drive source to accelerate or decelerate said member.
In a printer including a print element and drive means for driving said element, electrical detent means for bringing said printing element to a stop at a desired location, said detent means including means for applying to said drive means a drive signal decreasing to zero at said location when said member is within a first zone extending a first predetermined distance in a first direction from said location, said drive signal being of reversed polarity when said member is within a second zone extending a second predetermined distance in the opposite direction from said location, said drive signal increasing in magnitude from zero at said location, and sample and hold means for holding the drive signal at the level and polarity it had in one of said zones after said member has moved to a position farther from said location than one of said predetermined distances.
Dependencies are inferred from the claim text.