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Hammer Rattling in a Line Printer

IP.com Disclosure Number: IPCOM000060590D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Davis, GW: AUTHOR [+3]

Abstract

The print hammers of a high speed line printer operate with modified flight times when inactive for a period of time as small as one or two print line cycles, thereby affecting the quality of print. A method is provided to rattle the print hammers not selected to print at the end of each print line cycle. Hammer rattling is the process of firing print hammers with reduced current sufficient to cause the hammers to physically move from the rest position but without causing the hammers to strike the print medium. Basically, the process is based on determining those print positions in the course of printing a line of data in which no printing will take place.

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Hammer Rattling in a Line Printer

The print hammers of a high speed line printer operate with modified flight times when inactive for a period of time as small as one or two print line cycles, thereby affecting the quality of print. A method is provided to rattle the print hammers not selected to print at the end of each print line cycle. Hammer rattling is the process of firing print hammers with reduced current sufficient to cause the hammers to physically move from the rest position but without causing the hammers to strike the print medium. Basically, the process is based on determining those print positions in the course of printing a line of data in which no printing will take place. The hammers at the unprinted positions are therefore addressed and energized with a firing pulse of shortened duration while the hammers selected for printing will be energized with pulses of normal duration. Subsequently, when the unprinted print position is called upon to print, the static condition of that hammer does not exist because it was disturbed by the rattle cycle from the previous line. Referring to the printer block diagram of Fig. 1, the Microprocessor Unit controls all print operations in the following manner: 1) Carriage move data and print data will be stored in the associated hardware electronic buffers as the Adapter Go signal is activated. This begins the firing of electromagnetic print hammers as the correct characters are moved in position by a rotating print band containing the character impressions. 2) When all print hammers have fired, the Carriage Go signal will be issued to the Carriage Control hardware 10 and the Print Complete Interrupt will be issued by Print Control hardware 11 to the Microprocessor Unit 12. This will begin the movement of the paper forms to position the paper for the next print line. The Carriage Complete...