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Print Ribbon Malfunction Detection System

IP.com Disclosure Number: IPCOM000046666D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Dyer, S: AUTHOR

Abstract

A print ribbon break detection system incorporates an immediate print system shut-off control to prevent print system damage upon ribbon malfunction. Retry logic allows the print system to again attempt printing after print ribbon advancement in order to override the effects of local ribbon flaws. The print system 11 supplies printing currents to a print ribbon 13 through a set of electrodes on head 15. The print ribbon 13 is layered so as to include a resistive layer adjacent the head 15, a conductive layer and a thermoplastic pigmented layer which is brought into contact with a writing sheet (not shown) located opposite head 15. Electrode drivers 17 selectively apply print current to various ones of the print electrodes which inject the current into the resistive layer of ribbon 13.

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Print Ribbon Malfunction Detection System

A print ribbon break detection system incorporates an immediate print system shut-off control to prevent print system damage upon ribbon malfunction. Retry logic allows the print system to again attempt printing after print ribbon advancement in order to override the effects of local ribbon flaws. The print system 11 supplies printing currents to a print ribbon 13 through a set of electrodes on head 15. The print ribbon 13 is layered so as to include a resistive layer adjacent the head 15, a conductive layer and a thermoplastic pigmented layer which is brought into contact with a writing sheet (not shown) located opposite head 15. Electrode drivers 17 selectively apply print current to various ones of the print electrodes which inject the current into the resistive layer of ribbon 13. The current injection produces localized heating, causing discrete portions of the ribbon's thermoplastic layer to melt and thus bond to the writing sheet to form a print mark on the sheet. All of the current is collected at a grounded electrode 18. In order to print patterns of print marks and thus form characters or the like, the head 15 and ribbon 13 are moved relative to the sheet and the electrode drivers 17 are gated by a clocked printer control device 19 which is in turn responsive to a character font generator 21. When a ribbon failure such as a ribbon break occurs, it is desirous to immediately shut down the electrode drivers 17 in order to prevent them from being damaged. In order to detect a ribbon break, the voltage on the resistive surface of the print ribbon 13 is monitored by the contact 25 and threshold detector 27. Contact 25 is located at the side of printhead 15 away from grounded electrode 18 to establish a detection circuit that includes the printhead/ribbon interface and the section of ribbon 13 extending between the print point and location of the contact 25. The threshold detector 27 may include individual comparators with fixed reference voltage inputs that correspond to predetermined thresholds for abnormal operation. An abnormally high level and an abn...