US 4,376,411 AGranted

Print hammer limit control

AssigneeInternational Business Machines Corporation

InventorsJames E. Carrington, Gerald R. Westcott

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Abstract

A hammer limit control for an on-the-fly line printer comprises a counter which counts compare signals from a compare circuit which detects coincidences of print data and type position data in synchronism with the motion of an endless type carrier. The counter maintains a running count of the number of compare signals for a control interval having a duration which is a function of the printing interval of a print line cycle. A hammer on storage device stores a plurality of compare counts registered by the counter at the end of each of a plurality of control intervals. An adder adds the running count registered in the counter to the total count stored in the storage means and stores the total sum in a hammer on register. When the total sum in the hammer on register equals a maximum number, a limit comparator generates a control signal which inhibits further comparisons by the compare circuit. The content of the hammer on storage device is updated each control interval by transferring the compare count registered in the compare counter to the storage device and by deleting the oldest count in the hammer on storage after a predetermined number of control intervals. The maximum number is stored in a register which is programmable.

Claims14

Dependent claims

A printer control system for use in a line printer wherein said line printer comprises a row of print hammers electrically operable for recording data at a plurality of print positions of a print line, a moving type carrier for cyclically presenting type characters at each print position of said print line in sequential print intervals of a print line cycle, and print control means for providing selection signals to hammer operating circuitry for controlling the turn on of said print hammers to effect printing operations in accordance with stored print data and type position data presented during said sequential print intervals in synchronism with the movement of said type characters, said print control means including a hammer limit control comprising

first means operative in response to said selection signals provided by said control means for indicating the number of hammers being selected to be turned on in a given control interval whose duration is a function of said print intervals,
second means for indicating the number of print hammers selected to be turned on in a plurality of said control intervals preceding said given control interval,
said plurality of control intervals having a duration which is a function of the turn on time of said print hammers,
means responsive to the combined number of hammers indicated by said first and second means for predicting at any instant of said control interval the total number of print hammers to be turned on, and
means responsive to said predicting means for preventing the selection of said print hammers for turning on when said predicted total number of hammers equals a predetermined maximum number.

2 more elements

Dependencies are inferred from the claim text.