| 摘要 |
PURPOSE:To prevent a printing wire from catching an ink ribbon and contrive a longer useful life and higher reliability of a printing head, by providing a contact member instantaneously displaced when the tension of the ink ribbon reaches or exceeds a predetermined value, on the upstream side of ribbon hauling-in rollers. CONSTITUTION:On the upstream side of ribbon hauling-in rollers 12, a leaf spring 26 makes contact with an ink ribbon 10. When a printing wire bites into the ink ribbon 10 during printing in the direction opposite to an arrow 13, the ribbon 10 is caught by the wire, and tends to be drawn out in the direction opposite to the feeding direction thereof, resulting in an increase in the tension on the ribbon 10. When the tension reaches or exceeds a predetermined value, the tip 31 of the spring 26 clears a projected part 34 into a recessed part 36, and is vibrated. At this moment, the tension acting on the ribbon 10 is quickly lowered (the two-dotted chain line condition), whereby the printing wire is released from the ribbon 10. Thereafter, the leaf spring 26 returns into an initial condition under the elastic restoring force thereof. |
