Browse Prior Art Database

Control of Printers with Hammers Serving Several Positions

IP.com Disclosure Number: IPCOM000083532D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Martin, BR: AUTHOR [+2]

Abstract

Referring to Fig. 1, a schematic arrangement of print hammers 10 is shown where the hammers impact type 12 on a belt or the like, for printing in each of two adjacent print positions. Each hammer must therefore be fired twice to complete a line of print, unless some of the columns are blank.

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Control of Printers with Hammers Serving Several Positions

Referring to Fig. 1, a schematic arrangement of print hammers 10 is shown where the hammers impact type 12 on a belt or the like, for printing in each of two adjacent print positions. Each hammer must therefore be fired twice to complete a line of print, unless some of the columns are blank.

According to present practice, printing occurs first in the left-hand column in front of each print hammer and when all the left-hand columns have been printed, the right-hand columns are scanned until all right-hand columns are printed.

Improved performance is obtained by examining all print positions, and printing either left or right columns whenever a character comes into a print position. This technique can be described as interleaved scanning.

To prevent conflicts which might call for the same hammer to print in adjacent columns at times which are so close that the print hammer does not have sufficient time to settle out between firings, a timing device is utilized for each hammer. If it is at zero the hammer can be fired and the timer is started. When a subsequent character is to be printed by this hammer the counter is checked, and if it registers zero the hammer can fire. If not, the hammer must wait till a later time when another character is positioned to be printed.

It is essential in any form of interleaved scanning that a print hammer should be prevented from having to fire twice in a period less than the hammer recovery time. However, if a hammer has opportunity to print in two columns within such a time it is not essential to print the character that appears in position firs...