Browse Prior Art Database

End of Ribbon Detector

IP.com Disclosure Number: IPCOM000089468D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Helinski, EF: AUTHOR

Abstract

A detector for accurately and reliably indicating the exhaustion of ribbon on a spool is constructed by providing a spool core which is operable to shift its position after a predetermined quantity of ribbon has been used.

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End of Ribbon Detector

A detector for accurately and reliably indicating the exhaustion of ribbon on a spool is constructed by providing a spool core which is operable to shift its position after a predetermined quantity of ribbon has been used.

Referring to Fig. 1, a full roll of ribbon 1 is wound on a core 2 which is placed over a shaft 3. Also placed within the core and over the shaft is a hub 4. The shaft has upper and lower sections 5, 6, each of which are round but whose axes are shifted with respect to each other. At the juncture an angular transition step 7 is made. The reduced diameter 8 of the hub is held against shaft step 7 by spring 9 acting downwardly. With a full spool, the hub cannot pass over the step because its internal diameter is too small. There are no moments clockwise about the stop while the ribbon is resting on a ledge 10. The total force of the spring plus the weight of the spool is supported on the ledge and the step on the shaft. The proportions of the weight acting on these two points can be altered by changing the diameter of the shaft and the distance from the step to the ledge.

This arrangement minimizes the force acting on the ledge and reduces ribbon damage and binding. It will be seen that equilibrium is maintained until a point is reached where the spool diameter is sufficiently small so that it is no longer supported by the ledge. The spool then falls off the ledge rotating counterclockwise about step 7. It is forced downward...