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Enhanced Duty Cycle Prediction And Control For Wire Matrix Printers

IP.com Disclosure Number: IPCOM000048904D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Cavill, BR: AUTHOR [+5]

Abstract

Typically, matrix printers of the past have generated characters that are limited in the number of dots per character, since they were held in read-only storage (ROS). This meant that the machine was designed to print the stored images. In the current series of printers, the character images to be printed are not restricted to those with a small number of dots per character. This presents additional problems including power supply loading, ribbon loading due to increased forces from the actuators hitting the ribbon, paper and platen, and additional heating. The present system permits design for expected typical printing loads while allowing heavy dense characters with no adverse consequences.

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Enhanced Duty Cycle Prediction And Control For Wire Matrix Printers

Typically, matrix printers of the past have generated characters that are limited in the number of dots per character, since they were held in read-only storage (ROS). This meant that the machine was designed to print the stored images. In the current series of printers, the character images to be printed are not restricted to those with a small number of dots per character. This presents additional problems including power supply loading, ribbon loading due to increased forces from the actuators hitting the ribbon, paper and platen, and additional heating. The present system permits design for expected typical printing loads while allowing heavy dense characters with no adverse consequences.

This line analysis system is part of the standard printer controller, and it is not just a plot applications program. Because of the "load alternate character command", the character wire images can be considerably denser than for standard character images without going to a special plot mode. This means that the line analysis must be done inside the printer on a line to line basis.

Each line to be printed is analyzed by the printer controller. The characters to be printed in a line are sent to the printer via the communications link and are saved in the interface (I/F) buffer 11. The printer communications adapter 12 takes the characters to be printed (EBCDIC values) and formats the line to be printed in the text buffer 14. The dot images to be used for each character are saved in the "wire image RAM (random-access memory)" area 16. Then the printer control adapter 17 does the actual printing. Character dot patterns are acquired from the wire image RAM area by the printer control adapter, and the proper print actuators 18 are fired.

Line analysis takes place in the printer communications adapter 12. Each time a character is moved from the I/F buffer to the text buffer, the EBCDIC character value is used to look up the character image in the wire image RAM area. The total number of dots for that character are counted. If 20 or more dots are in the character, then a "heavy character counter" is incremented by one. In this manner, the number of heavy (dense) characters in a line can be counted. Also, an average number of dots per character are evaluated in the following manner. An "average dot counter" is initialized to C00 hex at the start of each print cycle. For each character evaluated as above, the number of dots in that character is compared to an average character dot count of 14. The number of dots difference between the character being tested and the average is either added to, or subtracted from, the "average dot counter". This means that characters with less than 14 dots will decrease the "average dot counter" and those with more than 14 dots will increase the counter by the amount of the difference from 14. When the last characters of a short line or 2/3 of the char...