Electrically conductive ribbon break detector for printers
US4375339A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1980 |
| Grant date | Mar 1, 1983 |
| Priority date | — |
| Expiry date | Dec 1, 2000 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J35/36
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A ribbon feed failure in a printer can cause serious problems, particularly for a printer that uses heat to cause selective ink transfers. Localized heat buildup may injure the printhead and, if allowed to continue, might injure other printer instrumentalities. According to the invention, it is recognized that for ribbons having a degree of electrical conductivity, a mechanical ribbon failure will almost always result in a detectable change of electrical properties. By monitoring the characteristics of an electrical circuit passing through a section of the ribbon around the print point and, preferably, also the printhead-ribbon interface, abnormal electrical parameter values that indicate ribbon failure may be detected to trigger a cessation of printer operation. For a presently preferred implementation in a printer that uses a printhead with multiple electrodes for supplying current to a ribbon, the electrode voltage levels for a plurality of non-adjacent electrodes are combined to provide a resultant voltage level that is examined to detect abnormalities. By so combining voltages, insignificant excursions in electrical characteristics as might result from minor ribbon imperfectio…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.