| 摘要 |
A typewriter ribbon cassette contains a feed spool and a take-up spool which are both displaceably arranged in guide slots in the cassette housing. The guide slot for the feed spool leads to a control corner edge opening into an enlarged recess. The feed spool is biased with a spring force towards the control edge of the slot during unwinding of the ribbon roll, so that, when the feed spool has overrun the control edge, the spool is pivoted into a switching position which can be detected by a monitoring device for signalling an end of tape state of the ribbon roll. The hub of the feed spool is provided with a guide pilot for sliding along the guide slot which has a cornered plan profile for holding the hub in a straight line path along the slot until after the control edge is overrun. |
