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Fault Detection System for Band Printer Hammer Limit Controls

IP.com Disclosure Number: IPCOM000061692D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Crowell, JW: AUTHOR [+2]

Abstract

The hammer limit controls of a band printer use a buffer 10 for storing a hammer-on-table (HOT) consisting of data indicative of the number of hammers fired by print controls 11 as determined by compare counter 12 in each of a series of operating subscan intervals. The HOT data stored in buffer 10 is updated with the count in compare counter 12 at the end of each interval and the total table read from buffer 10 and summed by adder 13 for storage in end-of-scan (EOS) sum register 14 and hammer on register 15. In the course of each interval, the updated sum in EOS sum register 14 is increased to a new sum and stored in hammer on register 15 by adder 13 each time a hammer is fired.

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Fault Detection System for Band Printer Hammer Limit Controls

The hammer limit controls of a band printer use a buffer 10 for storing a hammer-on-table (HOT) consisting of data indicative of the number of hammers fired by print controls 11 as determined by compare counter 12 in each of a series of operating subscan intervals. The HOT data stored in buffer 10 is updated with the count in compare counter 12 at the end of each interval and the total table read from buffer 10 and summed by adder 13 for storage in end-of- scan (EOS) sum register 14 and hammer on register 15. In the course of each interval, the updated sum in EOS sum register 14 is increased to a new sum and stored in hammer on register 15 by adder 13 each time a hammer is fired. If the new sum exceeds a preset maximum in max hammer on register 16, comparator 17 inhibits print controls 11 from generating further compare signals which produce hammer firing. Normally, the hammer limit controls continue to update the HOT in buffer 10 until the updated sum in hammer on register 15 drops below the maximum whereupon comparator 17 removes the compare inhibit signal to allow print controls 11 to continue the sequence of subscans of its print and band image buffers (not shown) to reinstitute hammer firing. A method of checking the hammer limit control uses a technique which operates the hammers in accordance with a predetermined test pattern which, in the course of a single print scan, does not exceed the maximum in max hammer on register 15 and then causes print controls 11 to stop further scanning and generating compare signals for firing hammers by forcing a hammer check fault to occur. The test is done by storing a predetermined print test pattern in the print buffer along with known type data in a band image buffer of the print controls 11. After the type band is brought up to speed and the home position determined, print controls 11 scan its print buffer and band image buffer to generate print compare signals in accordance with the test pattern data in the print buffer for counting by compare counter 12. At the end of each test subscan interval, the count in compare counter 12 is stored in buffer 10 and the table summed, as previously described. At the end of a predetermined number of test subscan intervals equal to the number of HOT storage locations in buffer 10, the test process is terminated, the HOT is read...