Browse Prior Art Database

Hammer Firing Control in Belt Printers

IP.com Disclosure Number: IPCOM000089014D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Blythe, TJW: AUTHOR [+2]

Abstract

In line printers, a plurality of print hammers can be fired during each print cycle. Controlling the maximum number of print hammers which can be fired over a period of time is a problem with this type of printer. If the number of firings are counted in relation to a signal representative of the time interval over which the firings took place, the number of firings permitted can be maximized without the risk of overloading or otherwise damaging the printer.

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Hammer Firing Control in Belt Printers

In line printers, a plurality of print hammers can be fired during each print cycle. Controlling the maximum number of print hammers which can be fired over a period of time is a problem with this type of printer. If the number of firings are counted in relation to a signal representative of the time interval over which the firings took place, the number of firings permitted can be maximized without the risk of overloading or otherwise damaging the printer.

Up/Down Counter 11 is incremented by pulses from clock 12 via AND gate 13 and decremented by pulses on line 14. Pulses on line 14 indicate a print hammer has been selected for firing. Decoder 16 detects the count in counter
11. The maximum permitted count in counter 11 corresponds to the number of hammers which can be fired during a single cycle. Decoder 16 inhibits incrementing of counter 11 by clock 12 when counter 11 reaches the maximum count via inverter 18 and gate 13. When decoder 16 detects a zero value, line 9 becomes active to inhibit hammer selection on line 21 and, through inverter 20, this logic arrangement the hammer firing pulses are only inhibited where an overload or other unstable condition would result.

Clock 12 is set to pulse at intervals of l/N(p) (where N(p) is the average number of hammer firings per second which can be sustained) so the inhibit logic will set a variable limit on hammer firings during any particular cycle L. The variable limit is in...