Printer having ribbon wear indicator

Abstract From the Canadian patent

A dot matrix line printer is disclosed in which the amount of wear of an ink ribbon is measured by continuously compiling data representing impacting action of the printer as the printer prints. In a first embodiment this is accomplished by, initially determining a dot count based on the length of the ribbon and representing the maximum theoretical useful life of the ink ribbon and then decreasing the initial dot count as printing thereafter commences. The dot count remaining is continuously divided by the initial dot count to determine the percentage of ribbon life remaining. When the dot count has been decreased substantially to zero, a worn ribbon indication is provided to initiate an …